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Source characteristics of Jovian narrow-band kilometric radio emissions
NASA Astrophysics Data System (ADS)
Reiner, M. J.; Fainberg, J.; Stone, R. G.; Kaiser, M. L.; Desch, M. D.; Manning, R.; Zarka, P.; Pedersen, B.-M.
New observations of Jovian narrow-band kilometric (nKOM) radio emissions were made by the Unified Radio and Plasma Wave (URAP) experiment on the Ulysses spacecraft during the Ulysses-Jupiter encounter in early February 1992. These observations have demonstrated the unique capability of the URAP instrument for determining both the direction and polarization of nKOM radio sources. An important result is the discovery that nKOM radio emission originates from a number of distinct sources located at different Jovian longitudes and at the inner and outermost regions of the Io plasma torus. These sources have been tracked for several Jovian rotations, yielding their corotational lags, their spatial and temporal evolution, and their radiation characteristics at both low latitudes far from Jupiter and at high latitudes near the planet. Both right-hand and left-hand circularly polarized nKOM sources were observed. The polarizations observed for sources in the outermost regions of the torus seem to favor extraordinary mode emission.
Efficient narrow-band light emission from a single carbon nanotube pn diode
Perebeinos, Vasili
Efficient narrow-band light emission from a single carbon nanotube p┬Łn diode Thomas Mueller1. Here, we report electrically induced light emission from individual carbon nanotube p┬Łn diodes. A new building blocks of almost all of today's optoelectronic devices are p┬Łn junction diodes, including
Correlated pulsations in auroral light intensity and narrow band VLF emissions
H. J. Hansen; M. W. J. Scourfield; J. P. S. Rash
Observations at Sanae, Antarctica of pulsating aurora with a low light level TV system have been combined with simultaneous records of narrow band VLF emissions. Both auroral light and VLF intensities display a significant peak at 1.3▒0.3 Hz in the power spectrum. The peaks in the auroral light intensity variations lead those in the VLF by times between zero and
Narrow-band single-photon emission in the near infrared for quantum key distribution.
Wu, E; Jacques, Vincent; Zeng, Heping; Grangier, Philippe; Treussart, Franńois; Roch, Jean-Franńois
We present a detailed study of photophysical properties of single color centers in natural diamond samples emitting in the near infrared under optical excitation. Photoluminescence of these single emitters has several striking features, including narrow-band (FWHM 2 nm) fully polarized emission around 780 nm, a short excited-state lifetime of about 2 ns, and perfect photostability at room temperature under our excitation conditions. Development of a triggered single-photon source relying on this single color center is discussed for application to quantum key distribution. PMID:19503453
Analysis of the outlook for using narrow-band spontaneous emission sources for atmospheric air purification
Boyarchuk, K A; Karelin, A V; Shirokov, R V [Institute of Earth Magnetism, Ionosphere and Propagation of Radio waves, Russian Academy of Sciences, Moscow (Russian Federation)
The outlook for using narrow-band spontaneous emission sources for purification of smoke gases from sulphur and nitrogen oxides is demonstrated by calculations based on a nonstationary kinetic model of the N{sub 2} - O{sub 2} - H{sub 2}O - CO{sub 2} - SO{sub 2} mixture. The dependences of the mixture purification efficiency on the UV source power at different wavelengths, the exposure time, and the mixture temperature are calculated. It is shown that the radiation sources proposed in the paper will provide better purification of waste gases in the atmosphere. The most promising is a KrCl* lamp emitting an average power of no less than 100 W at 222 nm. (laser applications and other topics in quantum electronics)
LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Analysis of the outlook for using narrow-band spontaneous emission sources for atmospheric air purification
K. A. Boyarchuk; A. V. Karelin; R. V. Shirokov
The outlook for using narrow-band spontaneous emission sources for purification of smoke gases from sulphur and nitrogen oxides is demonstrated by calculations based on a nonstationary kinetic model of the N2 --- O2 --- H2O --- CO2 --- SO2 mixture. The dependences of the mixture purification efficiency on the UV source power at different wavelengths, the exposure time, and the
A 1.1-1.9 GHz SETI SURVEY OF THE KEPLER FIELD. I. A SEARCH FOR NARROW-BAND EMISSION FROM SELECT TARGETS
Siemion, Andrew P. V.; Korpela, Eric; Werthimer, Dan; Cobb, Jeff; Lebofsky, Matt; Marcy, Geoffrey W. [University of California, Berkeley, 110 Sproul Hall, Berkeley, CA 94720 (United States)] [University of California, Berkeley, 110 Sproul Hall, Berkeley, CA 94720 (United States); Demorest, Paul; Maddalena, Ron J.; Langston, Glen [National Radio Astronomy Observatory, 520 Edgemont Rd Charlottesville, VA 22903 (United States)] [National Radio Astronomy Observatory, 520 Edgemont Rd Charlottesville, VA 22903 (United States); Howard, Andrew W. [Institute for Astronomy, University of Hawaii, 640 North A'ohoku Place, 209 Hilo, HI 96720-2700 (United States)] [Institute for Astronomy, University of Hawaii, 640 North A'ohoku Place, 209 Hilo, HI 96720-2700 (United States); Tarter, Jill [SETI Institute, 189 Bernardo Ave 100 Mountain View, CA 94043 (United States)] [SETI Institute, 189 Bernardo Ave 100 Mountain View, CA 94043 (United States)
We present a targeted search for narrow-band (<5 Hz) drifting sinusoidal radio emission from 86 stars in the Kepler field hosting confirmed or candidate exoplanets. Radio emission less than 5 Hz in spectral extent is currently known to only arise from artificial sources. The stars searched were chosen based on the properties of their putative exoplanets, including stars hosting candidates with 380 K > T{sub eq} > 230 K, stars with five or more detected candidates or stars with a super-Earth (R{sub p} < 3 R{sub Circled-Plus }) in a >50 day orbit. Baseband voltage data across the entire band between 1.1 and 1.9 GHz were recorded at the Robert C. Byrd Green Bank Telescope between 2011 February and April and subsequently searched offline. No signals of extraterrestrial origin were found. We estimate that fewer than {approx}1% of transiting exoplanet systems host technological civilizations that are radio loud in narrow-band emission between 1 and 2 GHz at an equivalent isotropically radiated power (EIRP) of {approx}1.5 Multiplication-Sign 10{sup 21} erg s{sup -1}, approximately eight times the peak EIRP of the Arecibo Planetary Radar, and we limit the number of 1-2 GHz narrow-band-radio-loud Kardashev type II civilizations in the Milky Way to be <10{sup -6} M{sub Sun }{sup -1}. Here we describe our observations, data reduction procedures and results.
A 1.1-1.9 GHz SETI Survey of the Kepler Field. I. A Search for Narrow-band Emission from Select Targets
NASA Astrophysics Data System (ADS)
Siemion, Andrew P. V.; Demorest, Paul; Korpela, Eric; Maddalena, Ron J.; Werthimer, Dan; Cobb, Jeff; Howard, Andrew W.; Langston, Glen; Lebofsky, Matt; Marcy, Geoffrey W.; Tarter, Jill
We present a targeted search for narrow-band (<5 Hz) drifting sinusoidal radio emission from 86 stars in the Kepler field hosting confirmed or candidate exoplanets. Radio emission less than 5 Hz in spectral extent is currently known to only arise from artificial sources. The stars searched were chosen based on the properties of their putative exoplanets, including stars hosting candidates with 380 K > T eq > 230 K, stars with five or more detected candidates or stars with a super-Earth (R p < 3 R ?) in a >50 day orbit. Baseband voltage data across the entire band between 1.1 and 1.9 GHz were recorded at the Robert C. Byrd Green Bank Telescope between 2011 February and April and subsequently searched offline. No signals of extraterrestrial origin were found. We estimate that fewer than ~1% of transiting exoplanet systems host technological civilizations that are radio loud in narrow-band emission between 1 and 2 GHz at an equivalent isotropically radiated power (EIRP) of ~1.5 ū 1021 erg s-1, approximately eight times the peak EIRP of the Arecibo Planetary Radar, and we limit the number of 1-2 GHz narrow-band-radio-loud Kardashev type II civilizations in the Milky Way to be {<}10^{-6}\\ M^{-1}_\\odot. Here we describe our observations, data reduction procedures and results.
Narrow band gap amorphous silicon semiconductors
Madan, A.; Mahan, A.H.
Disclosed is a narrow band gap amorphous silicon semiconductor comprising an alloy of amorphous silicon and a band gap narrowing element selected from the group consisting of Sn, Ge, and Pb, with an electron donor dopant selected from the group consisting of P, As, Sb, Bi and N. The process for producing the narrow band gap amorphous silicon semiconductor comprises the steps of forming an alloy comprising amorphous silicon and at least one of the aforesaid band gap narrowing elements in amount sufficient to narrow the band gap of the silicon semiconductor alloy below that of amorphous silicon, and also utilizing sufficient amounts of the aforesaid electron donor dopant to maintain the amorphous silicon alloy as an n-type semiconductor.
Narrow-band generation in random distributed feedback fiber laser.
Sugavanam, Srikanth; Tarasov, Nikita; Shu, Xuewen; Churkin, Dmitry V
Narrow-band emission of spectral width down to ~0.05 nm line-width is achieved in the random distributed feedback fiber laser employing narrow-band fiber Bragg grating or fiber Fabry-Perot interferometer filters. The observed line-width is ~10 times less than line-width of other demonstrated up to date random distributed feedback fiber lasers. The random DFB laser with Fabry-Perot interferometer filter provides simultaneously multi-wavelength and narrow-band (within each line) generation with possibility of further wavelength tuning. PMID:23938497
Drummond, Tom
NARROW-BAND VOLUME RENDERING FOR FREEHAND 3D ULTRASOUND A. H. Gee, R. W. Prager, G. M. Treece and L Street Cambridge CB2 1PZ England Email: ahg/rwp/gmt11 @eng.cam.ac.uk, firstname.lastname@example.com #12; Narrow-Band ultrasound, for specifying these target volumes. The basic idea is to extend the familiar planar and non
The Stellar Population and Star Formation Rates of z~1.5-1.6 [O II] Emitting Galaxies Selected from Narrow-Band Emission-Line Surveys
Ly, Chun; Kashikawa, Nobunari; Hayashi, Masao; Nagao, Tohru; Shimasaku, Kazuhiro; Ota, Kazuaki; Ross, Nathaniel R
We present the first detailed study of the stellar populations of star-forming galaxies at z~1.5, which are selected by their [O II] emission line, detected in narrow-band surveys. We identified ~1,300 [O II] emitters at z=1.47 and z=1.62 in the Subaru Deep Field with rest-frame EWs above 13\\AA. Optical and near-infrared spectroscopic observations for ~10% of our samples show that our two-color identification of [O II] emission-line galaxies is 99% successful. We analyze the multi-wavelength properties of a subset of ~1,200 galaxies with the best photometry. They have average rest-frame EW of 45\\AA, stellar mass of 3 x 10^9 M_sun, and stellar age of 100 Myr. In addition, our SED fitting and broad-band colors indicate that [O II] emitters span the full range of galaxy populations at z~1.5. We also find that 80% of [O II] emitters are also photometrically classified as "BX/BM" (UV) galaxies and/or the star-forming "BzK" (near-IR) galaxies. Our [O II] emission line survey produces a far more complete, and somewh...
Narrow-band imaging: potential and limitations.
Kuznetsov, K; Lambert, R; Rey, J-F
The purpose of introducing optical electronics into video endoscopes is to improve the accuracy of diagnosis through image processing and digital technology. Narrow-band imaging (NBI), one of the most recent techniques, involves the use of interference filters to illuminate the target in narrowed red, green and blue (R/G/B) bands of the spectrum. This results in different images at distinct levels of the mucosa and increases the contrast between the epithelial surface and the subjacent vascular network. NBI can be combined with magnifying endoscopy with an optical zoom. The aim of this new technique is to characterize the surface of the distinct types of gastrointestinal epithelia - e. g., intestinal metaplasia in Barrett's esophagus. The technique may also make it possible to demonstrate disorganization of the vascular pattern in inflammatory disorders of the gastrointestinal mucosa and in superficial neoplastic lesions in the esophagus, stomach, and large bowel. PMID:16429359
Narrow-band imaging in digestive endoscopy.
Lambert, R; Kuznetsov, K; Rey, J-F
The application of opto-electronics in video-endoscopes improves the accuracy in diagnosis, through image processing and digital technology. Narrow Band Imaging (NBI), consists of using interference filters for the illumination of the target in narrowed blue and green bands of the spectrum. NBI is combined with magnifying endoscopy using an objective macro or an optical zoom. The NBI technique developed by Olympus Medical Systems is now available in the most recent models of video-endoscopes that use the non-sequential system of illumination (Lucera Spectrum) or the sequential R/G/B system of illumination (Exera II). The major contribution of the technique is in the characterization (analysis after detection) of the flat and superficial neoplastic areas of the digestive mucosa, with a specific application to the identification of intestinal metaplasia and early neoplastic changes in the Barrett's esophagus. The technique also proves helpful for the assessment of the vascular pattern in chronic inflammatory disorders of the digestive mucosa. PMID:17450308
Narrow band 3 ū 3 Mueller polarimetric endoscopy
Qi, Ji; Ye, Menglong; Singh, Mohan; Clancy, Neil T.; Elson, Daniel S.
Mueller matrix polarimetric imaging has shown potential in tissue diagnosis but is challenging to implement endoscopically. In this work, a narrow band 3 ū 3 Mueller matrix polarimetric endoscope was designed by rotating the endoscope to generate 0░, 45░ and 90░ linearly polarized illumination and positioning a rotating filter wheel in front of the camera containing three polarisers to permit polarization state analysis for backscattered light. The system was validated with a rotating linear polarizer and a diffuse reflection target. Initial measurements of 3 ū 3 Mueller matrices on a rat are demonstrated, followed by matrix decomposition into the depolarization and retardance matrices for further analysis. Our work shows the feasibility of implementing polarimetric imaging in a rigid endoscope conveniently and economically in order to reveal diagnostic information. PMID:24298405
Electrical and Optical Properties of Narrow-Band Materials
David Adler; Julius Feinleib
The electrical and optical properties of materials which are characterized by narrow bands in the vicinity of the Fermi energy are discussed. For such materials, electronic correlations and the electron-phonon coupling must be considered explicitly. Correlations in f bands and in extremely narrow d bands can be handled in the ionic limit of the Hubbard Hamiltonian. It is shown that
Narrow band images of suspected cooling flow galaxies
NASA Technical Reports Server (NTRS)
Deustua, Susana; Bothun, Greg
Narrow-band (H alpha and (NII)) charge coupled device (CCD) images of elliptical galaxies suspected of having cooling flows are discussed. Researchers find evidence of optical emission from cool gas which is most likely associated with a cooling flow. At least 4 galaxies (NGC 3998, NGC 4203, NGC 4550 and NGC 4697) show emission of (NII) and/or H alpha within the central 20 seconds, a fraction consistent with results from Phillips et al. (1987) and Caldwell (1984). In these four, (NII) lambda 6584A emission is stronger than H alpha (which is often in absorption e.g., as seen in long slit spectra of NGC4697). From long slit spectra of these galaxies, Deustua and Teske (1989) infer electron densities, N sub e, of order 1.2x10 to the 3rd power cm(-3) assuming T = 10 to the 4th power K for the optically emitting gas. NGC 2685, NGC 3489 appear to have emission in (NII); NGC 4636 may also, but, is difficult to see in the data (Demoulin-Ulrich, Butcher and Boksenberg (1984) did not see emission from this galaxy). NGC 4472, NGC 4473, NGC 4365, NGC 4638 and NGC 4649 show no emission.
The Narrow-Band Model and Semi-Conductor Theory
ERIC Educational Resources Information Center
Tanner, B. K.
Applies the narrow-band model to the instruction of intrinsic and extrinsic semiconductors along with the phenomenon of compensation. Advocates the model for undergraduate instruction due to its intuitive appeal and mathematical simplicity. (CP)
Robust Pitch Detection by Narrow Band Spectrum AnalysisĀ
Shimodaira, Hiroshi; Nakai, Mitsuru
This paper proposes a new technique for detecting pitch patterns which is useful for automatic speech recognition, by using a narrow band spectrum analysis. The motivation of this approach is that humans perceive some kind of pitch in whispers where...
Band-gap narrowing in novel III-V semiconductors
NASA Astrophysics Data System (ADS)
Jain, S. C.; McGregor, J. M.; Roulston, D. J.
A predictive model for band-gap narrowing has been applied to several III-V semiconductors. Band-gap narrowing is expressed as ?Eg =AN1/3+BN1/4+CN1/2 ; values for A, B, and C are predicted for these materials. The commonly used N1/3 relation is shown to be valid for the p-type materials considered, but not for n-type materials.
Tunable narrow band source via the strong coupling between optical emitter and nanowire surface plasmons
J. Yang; G. W. Lin; Y. P. Niu; Y. H. Qi; F. X. Zhou; S. Q. Gong
The spectrum width can be narrowed to a certain degree by decreasing the coupling strength for the two-level emitter coupled to the propagating surface plasmon. But the width can not be narrowed any further because of the loss of the photon out of system by spontaneous emission from the emitter. Here we propose a new scheme to construct a narrow-band source via a one-dimensional waveguide coupling with a three-level emitter. It is shown that the reflective spectrum width can be narrowed avoiding the impact of the loss. This approach opens up the possibility of plasmonic ultranarrow single-photon source.
Ultrafast Narrow Band Modulation of VCSELs
NASA Technical Reports Server (NTRS)
Ning, Cun-Zheng; Biegel, Bryan A. (Technical Monitor)
Multimode beating was greatly enhanced by taking output from part (e.g., half) of the output facet. Simpler sources of microwaves and millimeter waves of various frequencies were generated by varying the VCSEL diameter in a single multimode VCSEL our coupling of a few VCSELs. Breathing frequency in multi-mode operations affects modulation response and bandwidth. Optimizing RO frequency and mode beating frequency could potentially expand bandwidths suitable for wide band digital communications.
Edinburgh, University of
ROBUST PITCH DETECTION BY NARROW BAND SPECTRUM ANALYSIS Hiroshi SHIMODAIRA and Mitsuru NAKAI, Tohoku University, Sendai-shi, 980 JAPAN ABSTRACT This paper proposes a new technique for detecting pitch. The motivation of this ap- proach is that humans perceive some kind of pitch in whispers where no fundamental
Spontaneous emission through heavy photon bands
NASA Astrophysics Data System (ADS)
Yannopapas, Vassilios
We examine the spontaneous emission spectrum of a Lgr-type three-level atom embedded in a coupled-resonator optical waveguide. Owing to the high degree of confinement of light within the resonators, the waveguide modes can be obtained in the framework of an electromagnetic tight-binding theory. The corresponding density of modes exhibits singularities at the band edges leading to interesting features in the spontaneous emission spectrum such as dark lines and narrow emission peaks. The position and the shape of these features depend strongly on the geometry and refractive index of the waveguide.
A narrow band pattern-matching model of vowel perception
NASA Astrophysics Data System (ADS)
Hillenbrand, James M.; Houde, Robert A.
The purpose of this paper is to propose and evaluate a new model of vowel perception which assumes that vowel identity is recognized by a template-matching process involving the comparison of narrow band input spectra with a set of smoothed spectral-shape templates that are learned through ordinary exposure to speech. In the present simulation of this process, the input spectra are computed over a sufficiently long window to resolve individual harmonics of voiced speech. Prior to template creation and pattern matching, the narrow band spectra are amplitude equalized by a spectrum-level normalization process, and the information-bearing spectral peaks are enhanced by a ``flooring'' procedure that zeroes out spectral values below a threshold function consisting of a center-weighted running average of spectral amplitudes. Templates for each vowel category are created simply by averaging the narrow band spectra of like vowels spoken by a panel of talkers. In the present implementation, separate templates are used for men, women, and children. The pattern matching is implemented with a simple city-block distance measure given by the sum of the channel-by-channel differences between the narrow band input spectrum (level-equalized and floored) and each vowel template. Spectral movement is taken into account by computing the distance measure at several points throughout the course of the vowel. The input spectrum is assigned to the vowel template that results in the smallest difference accumulated over the sequence of spectral slices. The model was evaluated using a large database consisting of 12 vowels in /h
Recovering physical properties from narrow-band photometry
NASA Astrophysics Data System (ADS)
Schoenell, W.; Cid Fernandes, R.; BenĒtez, N.; Vale Asari, N.
Our aim in this work is to answer, using simulated narrow-band photometry data, the following general question: What can we learn about galaxies from these new generation cosmological surveys? For instance, can we estimate stellar age and metallicity distributions? Can we separate star-forming galaxies from AGN? Can we measure emission lines, nebular abundances and extinction? With what precision? To accomplish this, we selected a sample of about 300k galaxies with good S/N from the SDSS and divided them in two groups: 200k objects and a template library of 100k. We corrected the spectra to z = 0 and converted them to filter fluxes. Using a statistical approach, we calculated a Probability Distribution Function (PDF) for each property of each object and the library. Since we have the properties of all the data from the STARLIGHT-SDSS database, we could compare them with the results obtained from summaries of the PDF (mean, median, etc). Our results shows that we retrieve the weighted average of the log of the galaxy age with a good error margin (? ? 0.1 - 0.2 dex), and similarly for the physical properties such as mass-to-light ratio, mean stellar metallicity, etc. Furthermore, our main result is that we can derive emission line intensities and ratios with similar precision. This makes this method unique in comparison to the other methods on the market to analyze photometry data and shows that, from the point of view of galaxy studies, future photometric surveys will be much more useful than anticipated.
Narrow-band single photon emission at room temperature based on a single nitrogen-vacancy center coupled to an all-fiber-cavity
NASA Astrophysics Data System (ADS)
Albrecht, Roland; Bommer, Alexander; Pauly, Christoph; M³cklich, Frank; Schell, Andreas W.; Engel, Philip; Schr÷der, Tim; Benson, Oliver; Reichel, Jakob; Becher, Christoph
We report the realization of a device based on a single Nitrogen-Vacancy (NV) center in diamond coupled to a fiber-cavity for use as single photon source (SPS). The device consists of two concave mirrors each directly fabricated on the facets of two optical fibers and a preselected nanodiamond containing a single NV center deposited onto one of these mirrors. Both, cavity in- and out-put are directly fiber-coupled, and the emission wavelength is easily tunable by variation of the separation of the two mirrors with a piezo-electric crystal. By coupling to the cavity, we achieve an increase of the spectral photon rate density by two orders of magnitude compared to free-space emission of the NV center. With this work, we establish a simple all-fiber based SPS with promising prospects for the integration into photonic quantum networks.
Narrow-band single photon emission at room temperature based on a single nitrogen-vacancy center coupled to an all-fiber-cavity
Albrecht, Roland; Bommer, Alexander; Becher, Christoph, E-mail: firstname.lastname@example.com [Universitõt des Saarlandes, Fachrichtung 7.2 (Experimentalphysik), Campus E2.6, 66123 Saarbr³cken (Germany); Pauly, Christoph; M³cklich, Frank [Universitõt des Saarlandes, Fachrichtung 8.4 (Materialwissenschaft und Werkstofftechnik), Campus D3.3, 66123 Saarbr³cken (Germany); Schell, Andreas W.; Engel, Philip; Benson, Oliver [Humboldt-Universitõt zu Berlin, Institut f³r Physik, AG Nanooptik, Newtonstra▀e 15, 12489 Berlin (Germany); Schr÷der, Tim [Department of Electrical Engineering and Computer Science, MIT, Cambridge, Massachusetts 02139 (United States); Humboldt-Universitõt zu Berlin, Institut f³r Physik, AG Nanooptik, Newtonstra▀e 15, 12489 Berlin (Germany); Reichel, Jakob [Laboratoire Kastler Brossel, ENS/UPMC-Paris 6/CNRS, 24 rue Lhomond, 75005 Paris (France)
We report the realization of a device based on a single Nitrogen-Vacancy (NV) center in diamond coupled to a fiber-cavity for use as single photon source (SPS). The device consists of two concave mirrors each directly fabricated on the facets of two optical fibers and a preselected nanodiamond containing a single NV center deposited onto one of these mirrors. Both, cavity in- and out-put are directly fiber-coupled, and the emission wavelength is easily tunable by variation of the separation of the two mirrors with a piezo-electric crystal. By coupling to the cavity, we achieve an increase of the spectral photon rate density by two orders of magnitude compared to free-space emission of the NV center. With this work, we establish a simple all-fiber based SPS with promising prospects for the integration into photonic quantum networks.
Airborne observations of the infrared emission bands
NASA Technical Reports Server (NTRS)
Cohen, M.; Bregman, J.; Witteborn, F. C.; Wooden, D. H.; Rank, D. M.; Demuizon, M. Jourdain; Allamandola, Louis J.; Tielens, Alexander G. G. M.
The data concerning low resolution airborne spectra from 5 to 8 microns available for a sample of 40 sources selected from the Infrared Astronomy Satellite low resolution spectral Atlas with polycyclic aromatic hydrocarbon (PAH) emission features, are discussed. A new emission band at 5.2 microns, previously predicted for PAHs, was found in 33 sources; it also correlates with the 7.7 microns band. This extends the spectrum of narrow observed PAH features to 3.3, 5.2, 5.6, 6.2, 6.9, 7.7, 8.7, 11.3, and 12.7 microns. From the data the relative strengths of most of these bands are defined in three separate nebular environments: planetaries, H II regions, and reflection nebulae. The differences in the PAHs spectra in those environments are analyzed.
Narrow-band oscillations in probabilistic cellular automata.
Puljic, Marko; Kozma, Robert
Dynamical properties of neural populations are studied using probabilistic cellular automata. Previous work demonstrated the emergence of critical behavior as the function of system noise and density of long-range axonal connections. Finite-size scaling theory identified critical properties, which were consistent with properties of a weak Ising universality class. The present work extends the studies to neural populations with excitatory and inhibitory interactions. It is shown that the populations can exhibit narrow-band oscillations when confined to a range of inhibition levels, with clear boundaries marking the parameter region of prominent oscillations. Phase diagrams have been constructed to characterize unimodal, bimodal, and quadromodal oscillatory states. The significance of these findings is discussed in the context of large-scale narrow-band oscillations in neural tissues, as observed in electroencephalographic and magnetoencephalographic measurements. PMID:18850928
Fast wavelength switching of narrow-band excimer lasers
NASA Astrophysics Data System (ADS)
Grebner, D.; M³ller, D.; Triebel, W.
A novel system was developed, which allows one to switch the wavelength of a narrow-band excimer laser between two successive light pulses at a repetition rate of at least 250 Hz. This is realized by a periodically driven piezo actuator, which is attached to the diffraction grating of the narrow-band KrF excimer laser. The achieved position accuracy of the grating leads to a wavelength reproducibility of ▒0.2 pm, which allows one to apply this system to laser spectroscopic investigations like LIF or LIPF of OH in flames. Using the fast wavelength switching system background reduced concentration and temperature fields in flames can be measured within one sequence. Some possible realized and planned applications like the measurement of gas temperature, the diagnostic of turbulent combustion processes, and the investigation of combustion processes under microgravity are discussed.
Narrow-band switched-capacitor bandpass filters
Novel circuits, based on theN-path (or pseudo-N-path) configuration, are described for the design of narrow-band switched-capacitor (SC) bandpass filters. For noncritical applications very simple and economical circuits, based on the simulation of passive or activeRCcircuits, can be used; for high-accuracy filtering tasks, more elaborate circuits (obtained from doubly terminated reactance ladders) are proposed. The resulting filters provide stable passband responses
Spectral narrowing of solid state lasers by narrow-band PTR Bragg mirrors
NASA Astrophysics Data System (ADS)
Chung, T.; Rapaport, A.; Chen, Y.; Smirnov, V.; Hemmer, M.; Glebov, L. B.; Richardson, M. C.; Bass, M.
Dramatic spectral narrowing of normally broad band lasers, Ti:Sapphire,Cr:LiSAF, and alexandrite was achieved by simply replacing the output mirror with a reflective, volumetric Bragg grating recorded in photo thermal refractive (PTR) glass. The output power of each laser was changed very slightly from that obtained using dielectric coated output mirrors with the same output coupling as the Bragg grating while spectral brightness increased by about three orders of magnitude.
Compact narrow-band THz radiation source based on photocathode rf gun
NASA Astrophysics Data System (ADS)
Li, Wei-Wei; He, Zhi-Gang; Jia, Qi-Ka
Narrow-band THz coherent Cherenkov radiation can be driven by a subpicosecond electron bunch traveling along the axis of a hollow cylindrical dielectric-lined waveguide. We present a scheme of compact THz radiation source based on the photocathode rf gun. On the basis of our analytic result, the subpicosecond electron bunch with high charge (800 pC) can be generated directly in the photocathode rf gun. According to the analytical and simulated results, a narrow emission spectrum peaked at 0.24 THz with 2 megawatt (MW) peak power is expected to gain in the proposed scheme (the length of the facility is about 1.2 m).
Narrow-band imaging optical chromocolonoscopy: advantages and limitations.
Emura, Fabian; Saito, Yutaka; Ikematsu, Hiroaki
Narrow-band imaging (NBI) is an innovative optical technology that modifies the center wavelength and bandwidth of an endoscope's light into narrow-band illumination of 415 +/- 30 nm. NBI markedly improves capillary pattern contrast and is an in vivo method for visualizing microvessel morphological changes in superficial neoplastic lesions. The scientific basis for NBI is that short wavelength light falls within the hemoglobin absorption band, thereby facilitating clearer visualization of vascular structures. Several studies have reported advantages and limitations of NBI colonoscopy in the colorectum. One difficulty in evaluating results, however, has been non-standardization of NBI systems (Sequential and non-sequential). Utilization of NBI technology has been increasing worldwide, but accurate pit pattern analysis and sufficient skill in magnifying colonoscopy are basic fundamentals required for proficiency in NBI diagnosis of colorectal lesions. Modern optical technology without proper image interpretation wastes resources, confuses untrained endoscopists and delays inter-institutional validation studies. Training in the principles of "optical image-enhanced endoscopy" is needed to close the gap between technological advancements and their clinical usefulness. Currently available evidence indicates that NBI constitutes an effective and reliable alternative to chromocolonoscopy for in vivo visualization of vascular structures, but further study assessing reproducibility and effectiveness in the colorectum is ongoing at various medical centers. PMID:18756593
Fatigue failure of materials under narrow band random vibrations. I.
NASA Technical Reports Server (NTRS)
Huang, T. C.; Hubbard, R. B.; Lanz, R. W.
A novel approach for the study of fatigue failure of materials under the multifactor influence of narrow band random vibrations is developed. The approach involves the conduction of an experiment in conjunction with various statistical techniques. Three factors including two statistical properties of the excitation or response are considered and varied simultaneously. A minimum of 6 tests for 3 variables is possible for a fractional f actorial design. The four coefficients of the predicting equation can be independently estimated. A look at 3 predicting equations shows the predominant effect of the root mean square stress of the first order equation.
Narrow-band tunable alexandrite laser with passive Q switching
Tyryshkin, I S [Institute of Atmospheric Optics, Siberian Branch, Russian Academy of Sciences, Tomsk (Russian Federation); Ivanov, N A; Khulugurov, V M [Scientific-Research Institute of Applied Physics, Irkutsk State University, Irkutsk (Russian Federation)
An alexandrite laser with a self-injection of narrow-band radiation into its cavity was developed. A Fabry - Perot interferometer and a diffraction grating were used as dispersive components in an additional cavity. The cavity was switched by an LiF crystal with F{sub 3}{sup -} colour centres. The laser generated a single pulse of {approx} 180 ns duration and of 1.5 mJ energy, and with a spectrum 5 x 10{sup -3} cm{sup -1} wide. The laser emitted in the spectral range 720 - 780 nm. (lasers, active media)
Narrow-band-gap conjugated chromophores with extended molecular lengths.
Liu, Xiaofeng; Sun, Yanming; Perez, Louis A; Wen, Wen; Toney, Michael F; Heeger, Alan J; Bazan, Guillermo C
The influence of extending the molecular length of donor-acceptor chromophores on properties relevant to organic optoelectronic devices has been studied by using two new narrow-band-gap systems. Most significantly, we find that the higher molecular weight systems exhibit higher thermal stabilities (beyond 200 ░C) when introduced into field effect transistor devices. It is also possible to fabricate bulk heterojunction solar cells using PC(61)BM with power conversion efficiencies >6%. These high values are not heavily influenced by the blend composition and are achieved without the influence of solvent additives or postdeposition thermal annealing. PMID:23214922
Narrow-band optical transmission of metallic nanoslit arrays
Sun Zhijun; Yang Ying; Zuo Xiaoliu [Department of Physics, Xiamen University, Xiamen 361005 (China)
Metallic nanoslit arrays usually demonstrate wide transmission bands for transverse-magnetic-polarized incidence light. Here, we show that by introducing multi-dielectric layers underneath the metallic structure layer on the substrate, a narrow peak is formed, whose bandwidth can be down to a few nanometers. Three types of resonance modes in the region under the metal layer are identified responsible for the formation of the peak, i.e., a two-dimensional cavity resonance mode, which supports optical transmission, and two in-plane hybrid surface plasmon resonance modes locating on both sides of the peak that suppresses the transmission. Such structures can be applied in advanced photonic devices.
Improving visualization techniques by narrow band imaging and magnification endoscopy.
Muto, Manabu; Horimatsu, Takahiro; Ezoe, Yasumasa; Morita, Shuko; Miyamoto, Shinichi
Endoscopy plays an important role in the early detection of gastrointestinal tract neoplasms. Using conventional white light or dye-based image enhanced endoscopy, it has been difficult to assess pre-malignant and early neoplastic lesions precisely. However, narrow band imaging (NBI) dramatically improves the detection of these lesions, particularly in combination with magnifying endoscopy. This allows the endoscopist to accomplish accurate diagnosis. Such enhanced detection of pre-malignant and early neoplastic lesions in the gastrointestinal tract should allow better targeting of biopsy, improved and more appropriate treatment, and thereby contribute to optimal quality of life and patient survival. PMID:19702901
Narrow band imaging: a wide field of possibilities.
Rey, J F; Kuznetsov, K; Lambert, R
The application of opto-electronic in video-endoscopes aims to improve accuracy in diagnosis, through image processing and digital technology. Narrow band imaging (NBI), one of the most recent techniques, consists of using interference filters for the illumination of the target in narrowed red, green, and blue (R/G/B) bands of the spectrum. This results in different images at distinct levels in the mucosa and increases the contrast of the epithelial surface and of the subjacent vascular network. NBI is combined to magnifying endoscopy with an optical zoom. After being studied in prototypes the opto-electronic technique, now available in the most recent models of video-endoscopes that use the sequential R/G/B system of illumination, should be adapted in the near future for the instruments utilizing the non-sequential system of illumination. This new technique aims to characterize the surface of the distinct types of digestive epithelia, including intestinal metaplasia in the Barrett's esophagus. The technique also allows characterizing the disorganization of the vascular pattern in inflammatory disorders of the digestive mucosa and in superficial neoplastic lesions in the esophagus, stomach, and large bowel. PMID:19858605
Photometric Type Ia supernova surveys in narrow-band filters
NASA Astrophysics Data System (ADS)
Xavier, Henrique S.; Abramo, L. Raul; Sako, Masao; BenĒtez, Narciso; CalvŃo, MaurĒcio O.; Ederoclite, Alessandro; MarĒn-Franch, Antonio; Molino, Alberto; Reis, Ribamar R. R.; Siffert, Beatriz B.; Sodrķ, Laerte.
We study the characteristics of a narrow-band Type Ia supernova (SN) survey through simulations based on the upcoming Javalambre Physics of the accelerating Universe Astrophysical Survey. This unique survey has the capabilities of obtaining distances, redshifts and the SN type from a single experiment thereby circumventing the challenges faced by the resource-intensive spectroscopic follow-up observations. We analyse the flux measurements signal-to-noise ratio and bias, the SN typing performance, the ability to recover light-curve parameters given by the SALT2 model, the photometric redshift precision from Type Ia SN light curves and the effects of systematic errors on the data. We show that such a survey is not only feasible but may yield large Type Ia SN samples (up to 250 SNe at z < 0.5 per month of search) with low core-collapse contamination (ś1.5 per cent), good precision on the SALT2 parameters (average ? _{m_B}=0.063, ? _{x_1}=0.47 and ?c = 0.040) and on the distance modulus (average ?? = 0.16, assuming an intrinsic scatter ?int = 0.14), with identified systematic uncertainties ?sys ? 0.10?stat. Moreover, the filters are narrow enough to detect most spectral features and obtain excellent photometric redshift precision of ?z = 0.005, apart from ś2 per cent of outliers. We also present a few strategies for optimizing the survey's outcome. Together with the detailed host galaxy information, narrow-band surveys can be very valuable for the study of SN rates, spectral feature relations, intrinsic colour variations and correlations between SN and host galaxy properties, all of which are important information for SN cosmological applications.
NIR Narrow- and Broad-Band Study of the SSA 22 Field
NASA Astrophysics Data System (ADS)
Tamura, Naoyuki; Ohta, Kouji; Maihara, Toshinori; Iwamuro, Fumihide; Motohara, Kentaro; Takata, Tadafumi; Iye, Masanori
Deep narrow- and broad-band near-infrared imaging observations of the central 2'ū2' region of the SSA 22 field were made with the near-infrared camera (CISCO) attached to the Subaru Telescope. Using a narrow-band filter centered at 2.033?m, [O III] ?5007 emitters at z ~ 3.06 +/- 0.02 were searched to examine star-forming activities in an over-density region where a clustering of Lyman Break Galaxies (LBGs) and Lyman ? emitter candidates around z = 3.09 was reported, though the targeted redshift is slightly different from that of the peak of the over-density region. Although one emitter candidate at z = 3.06 was detected, it is likely to be located at a redshift of between 1 and 2 judged based on multi-band photometry. Another emission-line object was detected in another narrow-band filter (``off band'' filter) centered at 2.120 ?m, which is identified with a galaxy at z = 0.132 (the emission line is Paschen ?). The K'-band imaging data revealed the presence of 12 Extremely Red Objects (EROs) with I814-K' gep 4. The distribution of the EROs does not seem to coincide with that of Lyman Break Galaxies or Lyman alpha; emitters at z ~ 3. The magnitudes and colors of the EROs are not consistent with those of passively evolving massive elliptical galaxies at z ~ 3. Candidates for counterparts of the submm sources detected with SCUBA are found; no EROs around the submm sources are found in our magnitude limit.
Engineering integrated pure narrow-band photon sources
Enrico Pomarico; Bruno Sanguinetti; Clara I. Osorio; Harald Herrmann; Rob Thew
Engineering and controlling well defined states of light for quantum information applications is of increasing importance as the complexity of quantum systems grows. For example, in quantum networks high multi-photon interference visibility requires properly devised single mode sources. In this paper we propose a spontaneous parametric down conversion source based on an integrated cavity-waveguide, where single narrow-band, possibly distinct, spectral modes for the idler and the signal fields can be generated. This mode selection takes advantage of the clustering effect, due to the intrinsic dispersion of the nonlinear material. In combination with a CW laser and fast detection, our approach provides a means to engineer a source that can efficiently generate pure photons, without filtering, that is compatible with long distance quantum communication. Furthermore, it is extremely flexible and could easily be adapted to a wide variety of wavelengths and applications.
Electronic structure and quantized surface electron accumulation of narrow band gap semiconductors
NASA Astrophysics Data System (ADS)
Colakerol, Leyla
Narrow band gap semiconductors play a crucial role in thin film photovoltaic cells and optoelectronics devices operating in the infrared region of visible spectrum. The interactions between the valence and conduction bands due to the narrow band gap have a big influence on the electronic structure and the device performance of these materials. The surface and bulk electronic properties of narrow band gap semiconductors were investigated using angle resolved photoelectron spectroscopy (ARPES), x-ray absorption spectroscopy and x-ray emission spectroscopy. Comparisons were made between the experimental results and density functional theory band structure calculations. Intrinsic electron accumulation near the surface of clean InN was directly observed by ARPES. The accumulation layer is discussed in terms of the bulk Fermi level (EF) lying below the pinned surface E F, with a confining potential formed normal to surface due to the downward band bending facilitated by donor type surface states or nitrogen vacancies. Various spectroscopic techniques were used to measure this band bending. The energy of the Fermi level and the size of the Fermi surface for these quantum well states could be controlled by varying the method of surface preparation and by the adsorption of potassium on the surface. Intermixing between the heavy and light hole valence bands in the intrinsic quantum well potential associated with the surface electron accumulation layer results in an inverted band structure, with the valence band maximum lying away from the Brillouin zone center. Similarly, the electronic band structure of CdO was investigated and quantized electron subbands were observed above the valence band maximum. The origin of the accumulation layer is discussed in terms of the bulk band structure of CdO calculated using quasi particle corrected density functional theory. High electron density at the surface of these materials provides new opportunities for potential device structures such as sensors, high frequency transmitters and field effect transistors. Therefore the study of their near surface electron accumulation and electronic structure is of importance in understanding the properties of these materials and discovering new application areas.
Col¾n, Knicole D.; Gaidos, Eric, E-mail: email@example.com [Department of Geology and Geophysics, University of Hawaii at Manoa, Honolulu, HI 96822 (United States)
GJ 1214 is a nearby M dwarf star that hosts a transiting super-Earth-size planet, making this system an excellent target for atmospheric studies. Most studies find that the transmission spectrum of GJ 1214b is flat, which favors either a high mean molecular weight or cloudy/hazy hydrogen (H) rich atmosphere model. Photometry at short wavelengths (<0.7 ?m) and in the K band can discriminate the most between these different atmosphere models for GJ 1214b, but current observations do not have sufficiently high precision. We present photometry of seven transits of GJ 1214b through a narrow K-band (2.141 ?m) filter with the Wide Field Camera on the 3.8 m United Kingdom Infrared Telescope. Our photometric precision is typically 1.7 ū 10{sup ¢3} (for a single transit), comparable with other ground-based observations of GJ 1214b. We measure a planet-star radius ratio of 0.1158 ▒ 0.0013, which, along with other studies, also supports a flat transmission spectrum for GJ 1214b. Since this does not exclude a scenario where GJ 1214b has an H-rich envelope with heavy elements that are sequestered below a cloud/haze layer, we compare K-band observations with models of H{sub 2} collision-induced absorption in an atmosphere for a range of temperatures. While we find no evidence for deviation from a flat spectrum (slope s = 0.0016 ▒ 0.0038), an H{sub 2}-dominated upper atmosphere (<60 mbar) cannot be excluded. More precise observations at <0.7 ?m and in the K band, as well as a uniform analysis of all published data, would be useful for establishing more robust limits on atmosphere models for GJ 1214b.
Unified Theory of Charge Transport in Wide-Band and Narrow-Band Semiconductors
NASA Astrophysics Data System (ADS)
Ortmann, Frank; Bechstedt, Friedhelm; Hannewald, Karsten
The charge carrier mobility is often calculated within one of the two limiting cases: wide bands or narrow bands. In the case of wide-band systems, usually pure band transport is assumed along with a calculated relaxation time. In contrast, for narrow-band materials, hopping is usually considered prevalent and the interaction with lattice vibrations is described within the polaron concept. In this talk, we will present a unified approach to the description of charge transport based upon the Kubo formalism applied to a Holstein Hamiltonian. As a result, we obtain an analytical formula for the temperature dependence and anisotropy of the mobility describing a seamless transition from band transport at low temperatures to hopping transport at high temperatures. The results are illustrated for naphthalene crystals and a comparison to previous approaches [1,2] is made. [3pt] [1] V.M. Kenkre, Phys. Lett. A 305, 443 (2002)[0pt] [2] K. Hannewald and P.A. Bobbert, Phys. Rev. B 69, 075212 (2004)
Narrow-band injection seeding of a terahertz frequency quantum cascade laser: Selection and suppression of longitudinal modes
NASA Astrophysics Data System (ADS)
Nong, Hanond; Pal, Shovon; Markmann, Sergej; Hekmat, Negar; Mohandas, Reshma A.; Dean, Paul; Li, Lianhe; Linfield, Edmund H.; Giles Davies, A.; Wieck, Andreas D.; Jukam, Nathan
A periodically poled lithium niobate (PPLN) crystal with multiple poling periods is used to generate tunable narrow-bandwidth THz pulses for injection seeding a quantum cascade laser (QCL). We demonstrate that longitudinal modes of the quantum cascade laser close to the gain maximum can be selected or suppressed according to the seed spectrum. The QCL emission spectra obtained by electro-optic sampling from the quantum cascade laser, in the most favorable case, shows high selectivity and amplification of the longitudinal modes that overlap the frequency of the narrow-band seed. Proper selection of the narrow-band THz seed from the PPLN crystal discretely tunes the longitudinal mode emission of the quantum cascade laser. Moreover, the THz wave build-up within the laser cavity is studied as a function of the round-trip time. When the seed frequency is outside the maximum of the gain spectrum the laser emission shifts to the preferential longitudinal mode.
Narrow-band injection seeding of a terahertz frequency quantum cascade laser: Selection and suppression of longitudinal modes
Nong, Hanond, E-mail: email@example.com; Markmann, Sergej; Hekmat, Negar; Jukam, Nathan, E-mail: email@example.com [Arbeitsgruppe Terahertz Spektroskopie und Technologie, Ruhr-Universitõt Bochum, Bochum 44780 (Germany); Pal, Shovon [Arbeitsgruppe Terahertz Spektroskopie und Technologie, Ruhr-Universitõt Bochum, Bochum 44780 (Germany); Lehrstuhl f³r Angewandte Festk÷rperphysik, Ruhr-Universitõt Bochum, Bochum 44780 (Germany); Mohandas, Reshma A.; Dean, Paul; Li, Lianhe; Linfield, Edmund H.; Giles Davies, A. [School of Electronic and Electrical Engineering, University of Leeds, Leeds LS2 9JT (United Kingdom); Wieck, Andreas D. [Lehrstuhl f³r Angewandte Festk÷rperphysik, Ruhr-Universitõt Bochum, Bochum 44780 (Germany)
A periodically poled lithium niobate (PPLN) crystal with multiple poling periods is used to generate tunable narrow-bandwidth THz pulses for injection seeding a quantum cascade laser (QCL). We demonstrate that longitudinal modes of the quantum cascade laser close to the gain maximum can be selected or suppressed according to the seed spectrum. The QCL emission spectra obtained by electro-optic sampling from the quantum cascade laser, in the most favorable case, shows high selectivity and amplification of the longitudinal modes that overlap the frequency of the narrow-band seed. Proper selection of the narrow-band THz seed from the PPLN crystal discretely tunes the longitudinal mode emission of the quantum cascade laser. Moreover, the THz wave build-up within the laser cavity is studied as a function of the round-trip time. When the seed frequency is outside the maximum of the gain spectrum the laser emission shifts to the preferential longitudinal mode.
Analysis of Narrow and Broad Profiles Observed for the ?6614 Diffuse Interstellar Band
NASA Astrophysics Data System (ADS)
Bernstein, L. S.; Clark, F. O.; Lynch, D. K.; Galazutdinov, G. A.
We present an analysis of the diverse spectral profiles observed for the ?6614 diffuse interstellar band (DIB). This includes the anomalous Herschel 36 profile, exhibiting a prominent, broad red tail, and the typically observed narrow profiles, exhibiting much narrower, but noticeable red tails. This study was motivated by the inability of previous rotational contour modeling work to account for the narrow and broad red tails. We show that the full profiles, for all the observations, can consistently be modeled as a superposition of two overlapping DIBs, with peaks at 6613.6 and 6614.2 ┼. Each DIB is plausibly fit using a prolate, parallel band, symmetric top spectral contour model. For ?6613.6, there are small differences in the rotational constants, less than 1%, between the upper and lower transition states; whereas, for ?6614.2, the differences are much larger, ~ ¢5%. These results are consistent with ?6614.2 being the source of the narrow and broad red tails. The fit residuals are shown to be consistent with contributions from overlapping spectra, attributed to closely spaced vibrational sequences, originating from low frequency vibrations. We suggest that such sequences may be the source of the anomalous broadening needed to obtain good spectral fits to narrow DIB profiles. We discuss how ?6614.2 and the other Herschel 36 extended red tail DIBs help bridge the association gap between the narrow, absorption DIBs and the even broader and more redshifted emission features observed for the Red Rectangle. Finally, the broader implications of this study, in the context of identifying DIB molecular carriers, are discussed.
A narrow-band search for Ly alpha emitting galaxies at z = 8.8
Cuby, J G; Lidman, C; LefĶvre, O; Gilmozzi, R; Moorwood, A; Van der Werf, P P
Aims: The first star forming galaxies in the early universe should be copious Ly alpha emitters, and may play a significant role in ionizing the intergalactic medium (IGM). It has been proposed that the luminosity function of Lya emitting galaxies beyond z~6 may be used to constrain the neutral fraction of the IGM during this epoch. In this work we report on a search for Ly alpha emitters at redshift 8.8. Methods: We performed a narrow band imaging programme using ISAAC at the ESO VLT. Seven fields, covering a total area of 31sq. arcmin and for which optical and broad band infra-red images have been obtained in the GOODS survey, were imaged to a limiting flux (respectively luminosity) of ~ 1.3 x 10^{-17} ergs.s^{-1}.cm^{-2} (respectively ~ 1.3 x 10^{43} ergs.s^{-1} in a narrow band filter centered in a region of low OH sky emission at 1.19 micron. Candidate Lyman alpha emitters are objects that are detected in the ISAAC NB images and undetected in the visible broad band images. Results: No z=8.8 Ly alpha emit...
Narrow Band Chandra X-ray Analysis of Supernova Remnant 3C391
Yang Su; Yang Chen
We present the narrow-band and the equivalent width (EW) images of the thermal composite supernova remnant (SNR) 3C391 for the X-ray emission lines of elements Mg, Si, & S using the Chandra ACIS Observational data. These EW images reveal the spatial distribution of the emission of the metal species Mg, Si, & S in the remnant. They have clumpy structure similar to that seen from the broadband diffuse emission, suggesting that they are largely of interstellar origin. We find an interesting finger-like feature protruding outside the southwestern radio border of the remnant, which is somewhat similar to the jet-like Si structure found in the famous SNR Cas A. This feature may possibly be the debris of the jet of ejecta which implies an asymmetrical supernova explosion of a massive progenitor star.
IP-based narrow-band videophone system
NASA Astrophysics Data System (ADS)
Zhang, Zhengbing; Zhu, Dongmei; Xue, Liang; Zhu, Guangxi
Architecture of an IP-based narrow-band videophone system is proposed in this paper for convenient videophone calls between any two computers even if being placed in two different LANs within network agents. The bandwidth need of each call is less than 256 kbps. The system consists of two kinds of entities: Videophone Terminals (VPT) and a Video Call Server (VCS). A VPT is actually a microcomputer program, composed of 4 primary parts, an audio codec, a video codec, a media deliverer/receiver and a call controller. The basic functions of the VCS include videophone number generation and management, access admission and address resolution. The VCS with a public IP address plays an important role in the system especially when a video call has to penetrate through network agents. Each VPT in the system gets its own external transport address from the VCS through registration process. A calling VPT would receive the external transport address of the called VPT from the VCS through address resolution. The proposed system works and is helpful to accelerate the realization of people's videophone dream over IP networks.
Narrow-band UVB treatment of vitiligo in Chinese.
Chen, Guan-Yu; Hsu, M Ming-Long; Tai, Han-Kuo; Chou, Tzu-Chieh; Tseng, Ching-Liang; Chang, Ho-Yuan; Lan, Cheng-Che Eric; Sheu, Hamm-Ming
Narrow-band ultraviolet B (NBUVB) phototherapy has recently been reported to be an effective and safe treatment modality for vitiligo. In the present report, we evaluated the efficacy and safety of NBUVB therapy for vitiligo in Chinese patients. Seventy-two vitiligo patients treated from 2000 to 2003, were included retrospectively (male: female=33:39, mean age: 38.5). Among them, 61 were non-segmental type and 11 the segmental type. Treatments were given two to three times a week for a maximum period of one year with an initial dose of 0.2 J/cm2 and a 0-20% increment each session (mean accumulation dose: 155.3 J/cm2). Computer image analysis by Supervise classification was used to estimate the area of vitiligo involvement before and after treatment. An excellent response (75-100% area of repigmentation) was obtained in 9 patients (12.5%) and a good response (50-75%) in 24 (33.3%), a moderate response (25-50%) in 20 (27.8%), and a poor response (0-25%) in 19 (26.4%). In summary, 45.8% of our patients had more than 50% repigmentation. Burns were a side effect in 5 patients (7%) and transient erythema with itching or xerosis was noted in 5 patients (7%). These results indicate that NBUVB phototherapy is an effective and safe treatment choice for generalized vitiligo. PMID:16361730
Narrow-band ELF events observed from South Pole Station
NASA Astrophysics Data System (ADS)
Heavisides, J.; Weaver, C.; Lessard, M.; Weatherwax, A. T.
Extremely Low Frequency (ELF) waves are typically in the range of 3 Hz - 3 kHz and can play a role in acceleration and pitch-angle scattering of energetic particles in the radiation belts. Observations of a not uncommon, but not well studied ELF phenomenon are presented with ground-based data from South Pole Station. The narrow-band waves last approximately one or two minutes maintaining bandwidth over the course of the event, begin around 100 Hz, decrease to about 70 Hz, and typically show a higher frequency harmonic. The waves have only been documented at four locations - Heacock, 1974 (Alaska); Sentman and Ehring, 1994 (California); Wang et al, 2005 and Wang et al, 2011 (Taiwan); and Kim et al, 2006 (South Pole). The waves observed at the South Pole are not detected when the Sun drops below a 10 degree elevation angle, which is not true for the other locations. We extend the study of Kim et al, 2006, and explore possible generation mechanisms including sunlit ionosphere and ion cyclotron wave modes, as well as correspondence with energetic particle precipitation.
Narrow band noise response of a Belleville spring resonator.
Lyon, Richard H
This study of nonlinear dynamics includes (i) an identification of quasi-steady states of response using equivalent linearization, (ii) the temporal simulation of the system using Heun's time step procedure on time domain analytic signals, and (iii) a laboratory experiment. An attempt has been made to select material and measurement parameters so that nearly the same systems are used and analyzed for all three parts of the study. This study illustrates important features of nonlinear response to narrow band excitation: (a) states of response that the system can acquire with transitions of the system between those states, (b) the interaction between the noise source and the vibrating load in which the source transmits energy to or draws energy from the load as transitions occur; (c) the lag or lead of the system response relative to the source as transitions occur that causes the average frequencies of source and response to differ; and (d) the determination of the state of response (mass or stiffness controlled) by observation of the instantaneous phase of the influence function. These analyses take advantage of the use of time domain analytic signals that have a complementary role to functions that are analytic in the frequency domain. PMID:23967926
Intensities, broadening and narrowing parameters in the ?3 band of methane
NASA Astrophysics Data System (ADS)
Es-sebbar, Et-touhami; Farooq, Aamir
The P-branch of methane?s ?3 band is probed to carry out an extensive study of the 2905-2908 cm-1 infrared spectral region. Absolute line intensities as well as N2-, O2-, H2-, He-, Ar- and CO2-broadening coefficients are determined for nine transitions at room temperature. Narrowing parameters due to the Dicke effect have also been investigated. A narrow emission line-width (~0.0001 cm-1) difference-frequency-generation (DFG) laser system is used as the tunable light source. To retrieve the CH4 spectroscopic parameters, Voigt and Galatry profiles were used to simulate the measured line shape of the individual transitions.
Whispering-Gallery-Mode Tunable Narrow-Band-Pass Filter
NASA Technical Reports Server (NTRS)
Savchenkov, Anatoliy; Iltchenko, Vladimir; Matsko, Andrey; Maleki, Lute
An experimental tunable, narrow-band-pass electro-optical filter is based on a whispering-gallery resonator. This device is a prototype of tunable filters needed for the further development of reconfigurable networking wavelength-division multiplexers and communication systems that utilize radio-frequency (more specifically, microwave) subcarrier signals on optical carrier signals. The characteristics of whispering-gallery resonators that make them attractive for such applications include high tuning speed, compactness, wide tuning range, low power consumption, and compatibility with single-mode optical fibers. In addition, relative to Fabry-Perot resonators, these devices offer advantages of greater robustness and lower cost. As described in several prior NASA Tech Briefs articles, a whispering-gallery resonator is a spheroidal, disk-like, or toroidal body made of a highly transparent material. It is so named because it is designed to exploit whispering-gallery electromagnetic modes, which are waveguide modes that propagate circumferentially and are concentrated in a narrow toroidal region centered on the equatorial plane and located near the outermost edge. The experimental whispering-gallery tunable filter (see figure) is made from a disk of Z-cut LiNbO3 of 4.8-mm diameter and 0.17-mm thickness. The perimeter of the disk is rounded to a radius of curvature of 100 m. Metal coats on the flat faces of the disk serve as electrodes for exploiting the electro-optical effect in LiNbO3 for tuning. There is no metal coat on the rounded perimeter region, where the whispering-gallery modes propagate. Light is coupled from an input optical fiber into the whispering-gallery modes by means of a diamond prism. Another diamond prism is used to couple light from the whispering-gallery modes to an output optical fiber. This device is designed and operated to exploit transverse magnetic (TM) whispering- gallery modes, rather than transverse electric (TE) modes because the resonance quality factors (Q values) of the TM modes are higher. If Q values were not of major concern, it would be better to use the TE modes because the electro-optical shifts of the TE modes are 3 times those of the TM modes.
Characterization of Narrow Band Filters for Infrared The Brfl and H 2 filters
Testi, Leonardo
Characterization of Narrow Band Filters for Infrared Astronomy The Brfl and H 2 filters L. Vanzi used in Infrared Astronomy. Our study mainly quantifies the effect of temperature and tilt angle: Infrared, Narrow Band Filters, Imaging Abbreviations: IR -- Infrared; NIR -- Near infrared JEL codes: D24
Narrow-Band Processing and Fusion Approach for Explosive Hazard Detection in FLGPR
Havens, Timothy
images provide a means to detect targets which have a unique narrow-band signature. Experimental resultsNarrow-Band Processing and Fusion Approach for Explosive Hazard Detection in FLGPR Timothy C FLGPR is its high dynamic range in response to different kinds of targets and clutter objects
Narrow-band imaging system with magnifying endoscopy for superficial esophageal lesions
Tatsuya Yoshida; Haruhiro Inoue; Shinsuke Usui; Hitoshi Satodate; Norio Fukami; Shin-ei Kudo
BackgroundBy assessing the intrapapillary capillary loop in esophageal mucosa, magnifying endoscopy can play an important role in the evaluation of superficial esophageal lesions. A newly developed narrow-band imaging system was applied to magnifying endoscopy in a clinical setting; the benefit of the narrow-band imaging system was evaluated.
47 CFR 80.1159 - Narrow-band direct-printing (NB-DP).
Code of Federal Regulations, 2014 CFR
...2014-10-01 false Narrow-band direct-printing (NB-DP). 80.1159 Section 80... ¦ 80.1159 Narrow-band direct-printing (NB-DP). NB-DP is a form of...the transmission and receipt of direct printing public correspondence. Ships must...
47 CFR 80.461 - Narrow-band direct-printing.
Code of Federal Regulations, 2014 CFR
...2014-10-01 2014-10-01 false Narrow-band direct-printing. 80.461 Section 80.461 Telecommunication FEDERAL...Stations Use of Telegraphy ¦ 80.461 Narrow-band direct-printing. Subpart H of this part lists the frequencies...
Narrow band imaging and long slit spectroscopy of UGC 5101
NASA Technical Reports Server (NTRS)
Stanga, R. M.; Mannucci, F.; Rodriguezespinosa, J. M.
UGC 5101 (z = 0.04; D is approximately equal to 240 Mpc) is one of the so called Ultraluminous IRAS sources. Two important properties of the members of this group are their L(sub IR) is greater than or equal to 10(exp 12) solar luminosity, and their space density in the universe up to z is less than 0.1 is equal or even larger than the space density of the quasars. Further noteworthy features of the Ultraluminous IRAS sources are their being morphologically peculiar and the fact that they all seem to host active nuclei in their center. We have observed UGC 5101 in an effort to study the interplay between the gas ionized by the central active nucleus and that gas ionized by other processes which may hold important clues to the understanding of the entire picture of this object. In particular these other ionizing processes could well be massive stars formed recently after the galactic encounter and shocks possibly also related to the galaxy collision. The data that we discuss were obtained between Dec. 1989 and Jan. 1992 with the WHT 4.2 m telescope using the two-arm spectrograph ISIS. Several spectral frames were obtained at three different position angles: PA 84--along the tail of the galaxy; PA 32--along the dust lane; and PA 110. The blue spectra are centered on the H beta line, while the red spectra are centered on the H alpha line. In the configuration we used for the long slit spectra, the spectral scale was 0.74 A per pixel, and the spatial scale was .37 arcsec per pixel; we also observed the H alpha region with a spectral scale of .37 A per pixel, at position angle 84. The narrow band images were obtained at the auxiliary port of ISIS, with a scale of .2 arcsec per pixel, and were centered at the H alpha wavelength, and on the adjacent continuum. The H alpha images and the spectra support the following model. UGC 5101 hosts an active nucleus; the NLR extends up to about 1.5 kpc and shows a complex velocity field, superimposed on the rotation curve of the galaxy. Besides the NLR, in the H alpha image are visible tow bright cones that extend up to 3 kpc along PA 32. The long slit spectra at PA 32 show that the velocity field of the gas in these regions is peculiar, while the ionization structure of the gas is similar to that of the NLR.
Narrow-band photography of Jupiter and Saturn.
NASA Technical Reports Server (NTRS)
Fountain, J. W.
An IR-sensitive vidicon was used in the 1 to 2 mu region, with narrow-bandwidth filters, for Jupiter photographs taken in April, 1971, and Saturn photographs taken in December, 1970. The changes in limb darkening and surface details observed at different wavelengths are discussed. The 37 Jupiter photographs and the 38 Saturn photographs are included.
High average power, narrow band 248 nm alexandrite laser system
Kuper, J.W.; Chin, T.C.; Papanestor, P.A. [AlliedSignal Inc., Morristown, NJ (United States)
A compact line-narrowed 248 nm solid state laser source operating at 15 mJ {at} 100 Hz PRF was demonstrated. Constraints due to thermal loading of components were addressed. Tradeoffs between pulse energy and repetition rate were investigated. A method for overcoming thermal dephasing in the THG material was achieved by scanning a slab shaped crystal.
Square-Patterned Narrow-Band Infrared Emitter for Filter Less Infrared Gas Sensor
NASA Astrophysics Data System (ADS)
Song, Jun Tae; Park, Joong Hee; Kyoo Lee, June; Choi, Ju Chan; Kong, Seong Ho
In this study, we proposed a square-patterned narrow-band infrared (IR) emitter for a filterless IR gas sensor. As a new method of infrared gas sensing compared with previous research, it is proposed that a narrow-band IR emitter fabricated by micro-electro-mechanical-systems (MEMS) technology be applied to analyze dimethyl ether [(CH3)2O] gas. The proposed IR emitter consists of a TiN/SiO2/TiN trilayer, where the top TiN layer is square-patterned. The IR emitter radiates emissions at wavelengths of 7.68 and 7.88 Ąm in accordance with the type of sample. The wavelength can be adjusted by changing the period of the surface pattern. The proposed IR emitter shows a narrow peak width (??/?) of 0.16-0.23. The apparatus for gas detection consists of the proposed IR emitter, a gas cell and a bolometric IR sensor based on amorphous SiGe:H. The change in electrical resistance of the gas detector during inflow of (CH3)2O gas, which has a fingerprint wavelength in the range of 7.6-10 Ąm, was much smaller than that during inflow of CO2 gas, because (CH3)2O absorbed its corresponding wavelength in the range of 7.6-10 Ąm. Because of the concentrated radiation of the IR emitter at the wavelength of 7.88 Ąm, (CH3)2O absorbs relatively large amounts of infrared energy. The electrical resistance of the gas detector changed linearly as the concentration of (CH3)2O gas increased in the range of 0 to 500 ppm.
Ultrafast optical control of group delay of narrow-band terahertz waves
Miyamaru, Fumiaki; Morita, Hiroki; Nishiyama, Yohei; Nishida, Tsubasa; Nakanishi, Toshihiro; Kitano, Masao; Takeda, Mitsuo W.
We experimentally demonstrate control over the group delay of narrow-band (quasi continuous wave) terahertz (THz) pulses with constant amplitude based on optical switching of a metasurface characteristic. The near-field coupling between resonant modes of a complementary split ring resonator pair and a rectangular slit show an electromagnetically induced transparency-like (EIT-like) spectral shape in the reflection spectrum of a metasurface. This coupling induces group delay of a narrow-band THz pulse around the resonant frequency of the EIT-like spectrum. By irradiating the metasurface with an optical excitation pulse, the metasurface becomes mirror-like and thus the incident narrow-band THz pulse is reflected without a delay. Remarkably, if we select the appropriate excitation power, only the group delay of the narrow-band THz pulse can be switched while the amplitude is maintained before and after optical excitation. PMID:24614514
Ultrafast optical control of group delay of narrow-band terahertz waves.
Miyamaru, Fumiaki; Morita, Hiroki; Nishiyama, Yohei; Nishida, Tsubasa; Nakanishi, Toshihiro; Kitano, Masao; Takeda, Mitsuo W
We experimentally demonstrate control over the group delay of narrow-band (quasi continuous wave) terahertz (THz) pulses with constant amplitude based on optical switching of a metasurface characteristic. The near-field coupling between resonant modes of a complementary split ring resonator pair and a rectangular slit show an electromagnetically induced transparency-like (EIT-like) spectral shape in the reflection spectrum of a metasurface. This coupling induces group delay of a narrow-band THz pulse around the resonant frequency of the EIT-like spectrum. By irradiating the metasurface with an optical excitation pulse, the metasurface becomes mirror-like and thus the incident narrow-band THz pulse is reflected without a delay. Remarkably, if we select the appropriate excitation power, only the group delay of the narrow-band THz pulse can be switched while the amplitude is maintained before and after optical excitation. PMID:24614514
Ultrafast optical control of group delay of narrow-band terahertz waves
NASA Astrophysics Data System (ADS)
Miyamaru, Fumiaki; Morita, Hiroki; Nishiyama, Yohei; Nishida, Tsubasa; Nakanishi, Toshihiro; Kitano, Masao; Takeda, Mitsuo W.
We experimentally demonstrate control over the group delay of narrow-band (quasi continuous wave) terahertz (THz) pulses with constant amplitude based on optical switching of a metasurface characteristic. The near-field coupling between resonant modes of a complementary split ring resonator pair and a rectangular slit show an electromagnetically induced transparency-like (EIT-like) spectral shape in the reflection spectrum of a metasurface. This coupling induces group delay of a narrow-band THz pulse around the resonant frequency of the EIT-like spectrum. By irradiating the metasurface with an optical excitation pulse, the metasurface becomes mirror-like and thus the incident narrow-band THz pulse is reflected without a delay. Remarkably, if we select the appropriate excitation power, only the group delay of the narrow-band THz pulse can be switched while the amplitude is maintained before and after optical excitation.
Further improvements in program to calculate electronic properties of narrow band gap materials
NASA Technical Reports Server (NTRS)
Patterson, James D.
Research into the properties of narrow band gap materials during the period 15 Jun. to 15 Dec. 1991 is discussed. Abstracts and bibliographies from papers presented during this period are reported. Graphs are provided.
47 CFR 80.361 - Frequencies for narrow-band direct-printing (NBDP), radioprinter and data transmissions.
Code of Federal Regulations, 2014 CFR
...Frequencies for narrow-band direct-printing (NBDP), radioprinter and data transmissions...Frequencies for narrow-band direct-printing (NBDP), radioprinter and data transmissions...coast stations for narrow-band direct-printing (NBDP) and data transmissions....
A Simple Nanometeric Plasmonic Narrow-Band Filter Structure Based on Metal¢Insulator¢Metal Waveguide
Jia Hu Zhu; Qi Jie Wang; Ping Shum; Xu Guang Huang
In this paper, a novel nanometeric plasmonic narrow- band filter consisting of a metal-insulator-metal waveguide and a cavity embedded in the metal is proposed and numerically demon- strated by using the finite difference time domain method. The physical mechanism of the filter is elucidated. The results reveal that a narrow-band spectrum notch-filtering function can be real- ized with the proposed
Narrow-band extremely low frequency (ELF) wave phenomena observed at South Pole Station
Hyomin Kim; Marc R. Lessard; James LaBelle; Jay R. Johnson
Extremely low frequency (ELF) magnetic pulsations which show a whistler-like spectral structure have been measured at South Pole Station. An initial survey of the first 70 days of data revealed narrow-band ELF pulsations with slowly varying frequency over time. The narrow-band (a few Hz) signatures maintain their bandwidth as their frequencies decrease from 110 to 50 Hz (and their second
S. D. Gunapala; S. V. Bandar
A 640x512 pixel, long-wavelength cutoff, narrow-band (?? \\/?~10%) quantum well infrared photodetector (QWIP) focal plane array (FPA), a four-band QWIP FPA in the 4-16 Ąm spectral region, and a broad-band (?? \\/?~42%) QWIP FPA having 15.4 Ąm cutoff have been demonstrated. I. INTRODUCTION The QWIPs discussed in this article utilize the photoe xcitation of electrons between the ground state and
Tolerability of magnifying narrow band imaging endoscopy for esophageal cancer screening
Yamasaki, Yasushi; Takenaka, Ryuta; Hori, Keisuke; Takemoto, Koji; Kawano, Seiji; Kawahara, Yoshiro; Okada, Hiroyuki; Fujiki, Shigeatsu; Yamamoto, Kazuhide
AIM: To compare the tolerability of magnifying narrow band imaging endoscopy for esophageal cancer screening with that of lugol chromoendoscopy. METHODS: We prospectively enrolled and analyzed 51 patients who were at high risk for esophageal cancer. All patients were divided into two groups: a magnifying narrow band imaging group, and a lugol chromoendoscopy group, for comparison of adverse symptoms. Esophageal cancer screening was performed on withdrawal of the endoscope. The primary endpoint was a score on a visual analogue scale for heartburn after the examination. The secondary endpoints were scale scores for retrosternal pain and dyspnea after the examinations, change in vital signs, total procedure time, and esophageal observation time. RESULTS: The scores for heartburn and retrosternal pain in the magnifying narrow band imaging group were significantly better than those in the lugol chromoendoscopy group (P = 0.004, 0.024, respectively, ANOVA for repeated measures). The increase in heart rate after the procedure was significantly greater in the lugol chromoendoscopy group. There was no significant difference between the two groups with respect to other vital sign. The total procedure time and esophageal observation time in the magnifying narrow band imaging group were significantly shorter than those in the lugol chromoendoscopy group (450 ▒ 116 vs 565 ▒ 174, P = 0.004, 44 ▒ 26 vs 151 ▒ 72, P < 0.001, respectively). CONCLUSION: Magnifying narrow band imaging endoscopy reduced the adverse symptoms compared with lugol chromoendoscopy. Narrow band imaging endoscopy is useful and suitable for esophageal cancer screening periodically. PMID:25759551
Total microcolony counting on the moving narrow culture band
Chenjin Jiang; Peihua Chen; Song Shan
A microcolony count method, by which all the microcolonies in a culture of known sample weight could be counted, is described. Briefly, a flat solid medium layer, having a band ditch of ca 1.7 mm wide, 60 mm long and 0.3 mm deep on its surface, was prepared with an aluminum frame. Then a sample suspension of known weight with
Narrow-Band Transmission System for Animated Line Images
A. M. Skellett
A method of transmission and reproduction of line images is described which utilizes a cathode-ray tube for reproduction, the spot of which is made to trace out the line image 20 or more times a second. In an experimental test, a drawing of a woman's head was reproduced with an equivalent total band width of approximately 2,600 cycles. This was
NICMOS Narrow-band Images of OMC-1
NASA Technical Reports Server (NTRS)
Schultz, Angela S. B.; Colgan, Sean W. J.; Erickson, E. F.; Kaufman, M. J.; Hollenbach, D. J.; O'Dell, C. R.; Young, E. T.; Chen, H.
We present images of a 90in. x 90in. field centered on BN in OMC-1, taken with the Near-Infrared Camera and MultiObject Spectrograph (NICMOS) aboard the Hubble Space Telescope. The observed lines are H2 1-0 S(l), Pa, [FeII] 1.64 pm, and the adjacent continua. The region is rich in interesting structures. The most remarkable are the streamers or "fingers" of H2 emission which extend from 15in. to 50in. from IRc2, seen here in unprecedented detail. Unlike the northern H2 fingers, the inner fingers do not exhibit significant [FeII] emission at theirdips, which we suggest is due to lower excitation. These observations also show that the general morphology of the Pa and [FeII] emission (both imaged for the first time in this region) bears a striking resemblance to that of the Ha and [SII] emission previously observed with WFPC2. This implies that these IR and optical lines are produced by radiative excitation on the surface of the molecular cloud. The Pa morphology of HH 202 is also very similar to its H a and [OIII] emission, again suggesting that the Pa in this object is photo-excited by the Trapezium, as has been suggested for the optical emission. We find evidence of shock-excited [FeII] in HH 208, where it again closely follows the morphology of [SII]. There is also H2 coincident with the [SII] and [FeII] emission, which may be associated with HH 208. Finally, we note some interesting continuum features: diffuse "tails" trailing from IRc3 and IRc4, more extensive observations of the "crescent" found by Stolovy, et al. (1998), and new observations of a similar oval object nearby. We also find a "V"-shaped region which may be the boundary of a cavity being cleared by IRc2.
Some advantages of wide over narrow band signals in the search for extraterrestrial intelligence \\/SETI
P. F. Clancy
The present interest in the search for narrow-band signals in connection with SETI as well as its reasons and implications are considered. As an alternative, and considering the advantages of spread spectrum techniques in terms of higher communications capacity, the use of a wide-band transmission strategy is examined. The effects of dispersion by the interstellar medium and its use for
Generation of Narrow-Band Hyperentangled Nondegenerate Paired Photons
NASA Astrophysics Data System (ADS)
Yan, Hui; Zhang, Shanchao; Chen, J. F.; Loy, M. M. T.; Wong, G. K. L.; Du, Shengwang
We report the generation of nondegenerate narrow-bandwidth paired photons with time-frequency and polarization entanglements from laser cooled atoms. We observe the two-photon interference caused by Rabi splitting with a coherence time of about 30 ns and a visibility of 81.8% which verifies the time-frequency entanglement of the paired photons. The polarization entanglement is confirmed by polarization correlation measurements which exhibit a visibility of 89.5% and characterized by quantum-state tomography with a fidelity of 90.8%. Taking into account the transmission losses and duty cycle, we estimate that the system generates hyperentangled paired photons into opposing single-mode fibers at a rate of 320 pairs per second.
Tracking photosynthetic efficiency with narrow-band spectroradiometry
NASA Technical Reports Server (NTRS)
Gamon, John A.; Field, Christopher B.
Narrow-waveband spectroradiometry presents the possibility of detecting subtle signals closely related to the current physiological state of vegetation. One such signal related to the epoxidation state of the xanthophyll cycle pigments, violaxanthin, antheraxanthin, and zeaxanthin is discussed. Recent advances in plant ecophysiology demonstrated a close relationship between these pigments and the regulatory state of photosystem 2 in photosynthesis. Our recent field studies of sunflower (Helianthus annuus) and oak (Quercus agrifolia) demonstrated that a 'xanthophyll signal' can be isolated from the diurnal reflectance spectra of intact canopies. Furthermore, the xanthophyll signal can be used to derive a 'physiological reflectance index' (PRI) that closely correlates with the actual photosynthetic efficiency (defined as the photosynthetic rate divided by the incident PAR) in closed canopies. If these signals were detectable in Airborne Visible/Infrared Imaging Spectrometers (AVIRIS) images, they could lead to improved remote estimates of photosynthetic fluxes.
Neutrino flux calculations for the AGS narrow band beam
Chi, C.; Kondakis, N.; Lee, W.; O'Brien, E.; O'Halloran, T.; Reardon, K.; Salman, S.; Blumenfeld, B.; Chichura, L.; Chien, C.Y.
Presented are results of calculations of nu/sub ..mu../ fluxes in the AGS neutrino beam with the new dichromatic horn. The wide band beam nu/sub ..mu../, as well as the nu/sub e/ backgrounds, are discussed. The nu/sub e//nu/sub ..mu../ ratio is about 8 x 10/sup -3/. The possible sources and magnitudes of uncertainties are discussed. Finally, the calculated fluxes are compared with beam measurements.
The relationship between rape biomass and narrow-band vegetation indices
NASA Astrophysics Data System (ADS)
Huang, Jingfeng; Wang, Yuan; Wang, Fumin; Wang, Xiuzhen
The Relationships between rape biomass and hyperspectral vegetation indices are investigated in this paper. The data for this study comes from field hyperspectral reflectance measurements of rape during 2002-2003 growing period. Reflectance was measured in discrete narrow bands between 350 and 2500 nm. Observed rape biomass included wet biomass (WBM including leaf wet biomass-LWBM, stem wet biomass-SWBM, fruit wet biomass-FWBM), and dry biomass(DBM: including leaf dry biomass-LDBM, stem dry biomass, fruit dry biomass-FDBM). Narrow band normalized difference vegetation index (NBNDVI) and narrow band ratio vegetation index (NBRVI)involving all possible two-band combinations of discrete channels was tested. Special narrow band lambda (?1) versus lambda (?2) plots of R2 values illustrate the most effective wavelength combinations (?1 and ?2) and band-width (??1 and ??2) for predicting rape biomass at different development stage. A strong relationship with rape biomass is located in red-edge, the longer portion of red, moisture-sensitive NIR, longer portion of the blue band, the intermediate portion of SWIR, and the longer portion of SWIR.
SoC design and implementation for high reliable narrow-band power-line communications
Sungsoo Choi; Won-Tae Lee; Sungha Yun; Young-Chul Rhee
This paper describes a dual-mode type architecture for a high reliable narrow-band power-line communication (PLC) modem, and its design and implementation of a system-on-a-chip (SoC). The designed architecture is based on a chirp modulation technique for the purpose of overcoming time variations of power-line channel environments in the narrow-bandwidth of the frequency range of 95 - 148.5 kHz. The designed
Deconvolving Contributions to the Narrow Emission-Line Spectra of Narrow-Line Seyfert 1s
NASA Astrophysics Data System (ADS)
Kraemer, Steven B.; Crenshaw, D. M.; Schmitt, H. R.; Dietrich, M.
We present a continuation of our study of ground-based spectra of a sample of 12 Narrow-Line Seyfert 1s (NLSy1s), obtained using the 1.5m telescope at CTIO. Previously, we had found similar emission line ratios in both NLSy1s and Broad-Line Seyfert 1s (BLSy1s), which suggests similar ionizing continua, although we noted that low-ionization lines, such as [O I] 6300A and such as [S II] 6716,6731A may be somewhat weaker in NLSy1s. Based on photo-ionization modeling, the spectra from both types must include a strong contribution from dense, highly ionized gas in the inner narrow-line region (NLR), as has been noted in the literature. Notably, we find that the average [O III] 5007A/[OII] 3727A ratio is ~ 3.5 in NLSy1s, as compared to ~ 6.5 in a similar-sized sample of BLSy1s, consistent with a strong contribution from star-formation in the former. It is unclear whether star-formation is more prevalent in NLSy1s, suggesting a unique stage in the evolution of the AGN, or whether they tend to lack an extended NLR, which overwhelms any contribution from star-formationand may be due to the orientation of the AGN with the host galaxy.
Band-gap narrowing in GaAs using a capacitance method
NASA Astrophysics Data System (ADS)
van Mieghem, P.; Mertens, R. P.; Borghs, G.; van Overstraeten, R. J.
Since the precise value of band-gap narrowing is difficult to determine, many values have been reported in the literature. Optical methods have been considered to yield the most accurate values. Here we present the results of capacitance measurements on abrupt GaAs diodes carried out at various temperatures. The value of band-gap narrowing is derived with use of a new formalism. The agreement between the values of band-gap narrowing obtained by this method and by optical methods is good, demonstrating the validity of the applied theory. In contrast with other electrical measurements, this method does not require the knowledge of material parameters such as mobility, lifetime, and diffusion constants, which are difficult to estimate.
Enhancement of narrow-band terahertz radiation from photoconducting antennas by optical pulse shaping.
Liu, Y; Park, S G; Weiner, A M
We report the use of optical pulse shaping to convert single femtosecond pulses into lower-intensity pulse sequences for excitation of photoconductive dipole antennas, which results in the generation of bursts of tunable narrow-band free-space terahertz radiation. Our experiments demonstrate that the use of such pulse sequences can significantly enhance the spectral amplitude of the narrow-band terahertz radiation by avoiding the saturation effects that occur with single-pulse excitation. Our technique also provides the capability for terahertz wave-form shaping. PMID:19881793
Motional Narrowing and Ergodic Bands in Excited Superdeformed States of {sup 194}Hg
Lopez-Martens, A. [C.S.N.S.M, IN2P3-CNRS, Batiment 104-108, 91405 Orsay (France); Doessing, T.; Herskind, B. [Niels Bohr Institute, DK-2100, Copenhagen (Denmark); Khoo, T. L.; Lauritsen, T.; Carpenter, M. P.; Janssens, R. V. F.; Hackman, G. [Argonne National Laboratory, Argonne, Illinois 60439 (United States); Matsuo, M. [Graduate School of Science and Technology, Niigata University, Niigata 950-2181 (Japan); Lee, I-Y.; Macchiavelli, A. O. [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Vigezzi, E. [INFN Sezione di Milano and Dipartimento di Fisica, Universita di Milano, Via Celoria 16, 20133 Milano (Italy); Yoshida, K. [Institue for Natural Science, Nara University, Nara 631-8502 (Japan)
The E{sub {gamma}}-E{sub {gamma}} coincidence spectra from the electromagnetic decay of excited superdeformed states in {sup 194}Hg reveal surprisingly narrow ridges, parallel to the diagonal. A total of 100-150 excited bands are found to contribute to these ridges, which account for nearly all the unresolved E2 decay strength. Comparison with theory suggests that these excited bands have many components in their wave functions, yet they display remarkable rotational coherence. This phenomenon can be explained in terms of the combination of shell effects and motional narrowing.
Motional narrowing and ergodic bands in excited superdeformed states of {sup 194}Hg.
Lopez-Martens, A.; Dossing, T.; Khoo, T. L.; Matsuo, M.; Herskind, B.; Lauritsen, T.; Carpenter, M. P.; Janssens, R. V. F.; Hackman, G.; Lee, I-Y.; Macchiavelli, A. O.; Vigezzi, E.; Yoshida, K.; C.S.N.S.M.; Niels Bohr Inst.; Niigata Univ.; LBNL; Univ. di Milano; Nara Univ.
The E{sub {gamma}}-E{sub {gamma}} coincidence spectra from the electromagnetic decay of excited superdeformed states in {sup 194}Hg reveal surprisingly narrow ridges, parallel to the diagonal. A total of 100-150 excited bands are found to contribute to these ridges, which account for nearly all the unresolved E2 decay strength. Comparison with theory suggests that these excited bands have many components in their wave functions, yet they display remarkable rotational coherence. This phenomenon can be explained in terms of the combination of shell effects and motional narrowing.
Additional stress-induced band gap narrowing in a silicon die
NASA Astrophysics Data System (ADS)
Furuhashi, Masayuki; Taniguchi, Kenji
Semiconductor devices have intrinsic mechanical stress due to two separate sources, silicon wafer processing and packaging. This intrinsic stress induces band gap narrowing and consequent degradation of device reliability. In this work, a silicon die that included shallow trench isolation structures was used with additional external compression to clarify the interaction effects on band gap narrowing between stresses induced by different factors. It was observed that the pressure coefficient due to the additional external compression is linearly dependent on the intrinsic tensile region/total region ratio of a p-n diode.
Submillimeter narrow emission lines from the inner envelope of IRC+10216
Nimesh A. Patel; Ken H. Young; Sandra Br³nken; Robert W. Wilson; Patrick Thaddeus; Karl M. Menten; Mark Reid; Michael C. McCarthy; Dinh-V-Trung; Carl A. Gottlieb; Abigail Hedden
A spectral-line survey of IRC+10216 in the 345 GHz band has been undertaken with the Submillimeter Array. Although not yet completed, it has already yielded a fairly large sample of narrow molecular emission lines with line-widths indicating expansion velocities of ~4 km/s, less than 3 times the well-known value of the terminal expansion velocity (14.5 km/s) of the outer envelope. Five of these narrow lines have now been identified as rotational transitions in vibrationally excited states of previously detected molecules: the v=1, J=17--16 and J=19--18 lines of Si34S and 29SiS and the v=2, J=7--6 line of CS. Maps of these lines show that the emission is confined to a region within ~60 AU of the star, indicating that the narrow-line emission is probing the region of dust-formation where the stellar wind is still being accelerated.
Analysis of Discrimination Techniques for Low-Cost Narrow-Band Spectrofluorometers
Aymerich, Ismael F.; Sßnchez, Albert-Miquel; Pķrez, Sergio; Piera, Jaume
The need for covering large areas in oceanographic measurement campaigns and the general interest in reducing the observational costs open the necessity to develop new strategies towards this objective, fundamental to deal with current and future research projects. In this respect, the development of low-cost instruments becomes a key factor, but optimal signal-processing techniques must be used to balance their measurements with those obtained from accurate but expensive instruments. In this paper, a complete signal-processing chain to process the fluorescence spectra of marine organisms for taxonomic discrimination is proposed. It has been designed to deal with noisy, narrow-band and low-resolution data obtained from low-cost sensors or instruments and to optimize its computational cost, and it consists of four separated blocks that denoise, normalize, transform and classify the samples. For each block, several techniques are tested and compared to find the best combination that optimizes the classification of the samples. The signal processing has been focused on the Chlorophyll-a fluorescence peak, since it presents the highest emission levels and it can be measured with sensors presenting poor sensitivity and signal-to-noise ratios. The whole methodology has been successfully validated by means of the fluorescence spectra emitted by five different cultures. PMID:25558997
Narrow band coronographic imaging of the bipolar nebula around the LBV R127
NASA Technical Reports Server (NTRS)
Clampin, Mark; Nota, Antonella; Golimowski, David A.; Leitherer, Claus
New high resolution narrow band coronographic images of the R127 nebula have been recently obtained. The nebula displays a bipolar morphology and is similar in appearance to the nebula around AG Carinae. The observations improve the values for the linear dimensions (1.9 x 2.2 pc) and yield an estimated nebular mass of 3.1 solar mass.
On the Theory of Error Rates for Narrow-Band Digital FM
The theory of error rates for narrow-band digital FM with limiter-discriminator detection and integrate and dump postdetection filtering is considered. The goal is that of simplifying the existing theory, which has evolved primarily in the frequency domain, and requires numerical integration and differentiation of Fourier series expansions, numerical convolution, and multibit pattern averaging. A fresh approach in the time domain,
Search for neutrino oscillations at the AGS with the narrow band beam
Chi, C.; Kondakis, N.; Lee, W.; O'Brien, E.; O'Halloran, T.; Reardon, K.; Salman, S.; Blumenfeld, B.; Chichura, L.; Chien, C.Y.
We have taken neutrino data with the Narrow Band Beam (NBB) at Brookhaven National Laboratory (BNL) in the summer and fall of 1985. We are in the process of completing the analysis of the NBB data. In this paper we present preliminary results of this analysis. We observe an anomalous appearance of electron neutrinos above the expected background. 3 refs., 16 figs., 3 tabs.
Monte Carlo Simulation of Radiation in Gases with a NarrowBand Model
Dufresne, Jean-Louis
Monte Carlo Simulation of Radiation in Gases with a Narrow┬ŁBand Model and a Net, Germany. published in ASME Journal of Heat Transfer, May 1996, pp.401┬Ł407 Abstract The Monte Carlo method with the Monte Carlo method : numerical efficiency becomes independent of optical thickness, strongly non uniform
Across-frequency loudness matches with pure tones and narrow-band noises
NASA Astrophysics Data System (ADS)
Gregan, Melanie J.; Schlauch, Robert S.
Loudness matches between stimuli that differ in frequency are difficult, presumably due to the strong pitch differences which make it challenging to focus on loudness exclusively. It is hypothesized that the use of stimuli with a less salient pitch percept (but that still permit relatively frequency-specific excitation of the cochlea) would allow for more accurate across-frequency loudness matches. This would permit more stable comparisons of loudness growth between frequency regions (corresponding to normal and elevated thresholds) as is often the need in studies involving hearing-impaired subjects. In this study, normal-hearing listeners were evaluated in loudness matching tasks with two types of stimuli: pure tones and narrow bands of noise (with corresponding center frequencies). Listeners matched the loudness of a stimulus in one frequency region with a stimulus in another frequency region. The stimuli were either two pure tones, two narrow-band noises, or a pure tone and a narrow-band noise. The results will be evaluated based on predictions from an excitation pattern model and transitivity to determine if more accurate predictions are possible using narrow-band noise stimuli. [Work supported by the University of Minnesota.
Current Status of Narrow-Band Imaging Magnifying Colonoscopy for Colorectal Neoplasia in Japan
S. Oba; S. Tanaka; Y. Sano; S. Oka; K. Chayama
The narrow-band imaging system can be used to examine the microvascular architecture and surface pattern on the mucosal surface with high sensitivity. The clinical significance of NBI observation is summarized as follows: (1) differential diagnosis of hyperplasia, adenoma, and carcinoma; (2) diagnosis according to the presence of a surface pattern as an alternative to magnifying endoscopic observation with dye spraying,
Temperature dependent narrow-band terahertz pulse generation in periodically poled crystals via difference frequency generation
NASA Astrophysics Data System (ADS)
Yu, N. E.; Lee, K. S.; Ko, D.-K.; Kang, C.; Takekawa, S.; Kitamura, K.
Femtosecond optical pulse is used to generate narrow-band terahertz pulses depending on a quasi-phase-matched condition in periodically poled lithium niobate (PPLN) and stoichiometric lithium tantalate (PPSLT) crystals by difference frequency generation. The origin of narrow-band THz generation proved that the two frequency components of the fs pulse contribute to the frequency mixing. By cryogenic cooling, the absorption of THz waves in the crystal is significantly reduced which results in efficient THz generation. Simultaneously generated forward and backward THz pulses were 1.38 and 0.65 THz with as narrow as the bandwidth of 32 GHz in the PPSLT sample. Temperature dependence of the generated THz waveforms had good agreement with the simulation result using one dimensional plane-wave propagation model.
Design of narrow band photonic filter with compact MEMS for tunable resonant wavelength ranging 100 nm
NASA Astrophysics Data System (ADS)
Liang, Guanquan; Lee, Chengkuo; Danner, Aaron J.
A prototype of planar silicon photonic structure is designed and simulated to provide narrow resonant line-width (ś2 nm) in a wide photonic band gap (ś210 nm) with broad tunable resonant wavelength range (ś100 nm) around the optical communication wavelength 1550 nm. This prototype is based on the combination of two modified basic photonic structures, i.e. a split tapered photonic crystal micro-cavity embedded in a photonic wire waveguide, and a slot waveguide with narrowed slabs. This prototype is then further integrated with a MEMS (microelectromechanical systems) based electrostatic comb actuator to achieve "coarse tune" and "fine tune" at the same time for wide range and narrow-band filtering and modulating. It also provides a wide range tunability to achieve the designed resonance even fabrication imperfection occurs.
The offset dependent behavior of narrow optical emission features in the Red Rectangle proto-planetary nebula
NASA Astrophysics Data System (ADS)
Wehres, N.; Linnartz, H.; van Winckel, H.; Tielens, A. G. G. M.
Context. The Red Rectangle proto-planetary nebula provides a unique laboratory to study the physical conditions and chemical processes in stellar outflows. Snapshots of the ongoing chemical evolution are obtained by monitoring spectra as function of the offset from the central star. Aims: The focus in this study is on the characterization of narrow optical emission features, that are superimposed on top of extended red emission (ERE). The primary aim is to provide a two-dimensional catalogue of these features for offsets varying from 3'' to 20'' from the central star. Methods: Medium resolution emission spectra for this catalogue have been obtained through optical long-slit measurements using the New Technology Telescope (EMMI-NTT) in La Silla, Chile. Results: The recorded spectra cover the range between 5550 and 6800 ┼. A complete overview of the central band positions and bandwidths (FWHMs) is provided for both stronger (previously reported) and weaker narrow features. Only some bands are omnipresent in the nebula outflows and other bands only appear further away from the central star. Conclusions: The optical emission bands show intensity variations over the nebula. We suggest that these variations reflect a spatially resolved photochemistry where larger species are photolysed, producing daughter molecules which may be the carriers of the optical emission bands. Based on observations collected at the European Southern Observatory, Chile. Program ID: 080.C-0814(A).
Using Narrow Band Photometry to Detect Young Brown Dwarfs in IC348
A. K. Mainzer; Ian S. McLean
We report the discovery of a population of young brown dwarf candidates in the open star cluster IC348 and the development of a new spectroscopic classification technique using narrow band photometry. Observations were made using FLITECAM, the First Light Camera for SOFIA, at the 3-m Shane Telescope at Lick Observatory. FLITECAM is a new 1-5 micron camera with an 8 arcmin field of view. Custom narrow band filters were developed to detect absorption features of water vapor (at 1.495 microns) and methane (at 1.66 microns) characteristic of brown dwarfs. These filters enable spectral classification of stars and brown dwarfs without spectroscopy. FLITECAM's narrow and broadband photometry was verified by examining the color-color and color-magnitude characteristics of stars whose spectral type and reddening was known from previous surveys. Using our narrow band filter photometry method, it was possible to identify an object measured with a signal-to-noise ratio of 20 or better to within +/-3 spectral class subtypes for late-type stars. With this technique, very deep images of the central region of IC348 (H ~ 20.0) have identified 18 sources as possible L or T dwarf candidates. Out of these 18, we expect that between 3 - 6 of these objects are statistically likely to be background stars, with the remainder being true low-mass members of the cluster. If confirmed as cluster members then these are very low-mass objects (~5 Mjupiter). We also describe how two additional narrow band filters can improve the contrast between M, L, and T dwarfs as well as provide a means to determine the reddening of an individual object.
47 CFR 80.219 - Special requirements for narrow-band direct-printing (NB-DP) equipment.
Code of Federal Regulations, 2014 CFR
...2014-10-01 false Special requirements for narrow-band direct-printing (NB-DP) equipment. 80.219 Section 80.219 Telecommunication...80.219 Special requirements for narrow-band direct-printing (NB-DP) equipment. NB-DP and data...
A narrow-band search for extraterrestrial intelligence (SETI) using the interstellar contact channel hypothesis
D. G. Blair; R. P. Norris; E. R. Troup; R. Twardy; K. J. Wellington; A. J. Williams; A. E. Wright; M. G. Zadnik
A search is reported for narrow spectral line emission from 176 targets (including 166 stars and seven globular clusers) at the hypothesized 'interstellar communications channel' frequency of 4.462336275 GHz (= pi times the neutral hydrogen line at 1.42 GHz) using the Parkes Radio telescope. The frequency was Doppler corrected for the solar barycenter, target barycenter, and cosmic microwave background (CMB)
Airborne observations of the infrared emission bands
NASA Technical Reports Server (NTRS)
Cohen, M.; Wooden, Diane; Tielens, Alexander G. G. M.; Bregman, Jesse D.; Witteborn, Fred C.; Rank, D.; Allamandola, Louis J.
Earlier airborne studies of the infrared bands between 5 and 8 microns have now been extended to a sample of southern sources selected from the IRAS Low Resolution Spectra (LRS) atlas. The correlation between the strongest bands at 6.2 and 7.7 microns is now based on a total sample of 40 sources and is very strong. A new emission band at 5.2 microns, previously predicted for polycyclic aromatic hydrocarbons (PAHs), is recognized in 27 sources; it too correlates with the dominant 7.7 micron band, showing that the 5.2 micron feature also belongs to the generic spectrum of PAH features at 3.3, 5.6, 6.2, 6.2, 7.7, 8.7, 11.3, and 12.7 microns. Sufficient sources are had now to define the relative strengths of most of these bands in three separate nebular environments: planetaries, H II regions, and reflection nebulae. Significant variations are detected in the generic spectra of PAHs in these different environments which are echoed by variations in the exact wavelength of the strong 7.7 micron peak. The earlier suggestion that, in planetaries, the fraction of total emission observed by IRAS that is carried by the PAH emissions is correlated with nebular gas-phase C/O ratio is supported by the addition of newly-observed southern planetaries, including the unusually carbon-rich (WC10) nebular nuclei. These (WC10) nuclei also exhibit a strong plateau of emission linking the 6.2 and 7.7 micron features.
UNIDENTIFIED INFRARED EMISSION BANDS: PAHs or MAONs?
Sun Kwok; Yong Zhang, E-mail: firstname.lastname@example.com [Department of Physics, University of Hong Kong, Pokfulam Road, Hong Kong (Hong Kong)
We suggest that the carrier of the unidentified infrared emission (UIE) bands is an amorphous carbonaceous solid with mixed aromatic/aliphatic structures, rather than free-flying polycyclic aromatic hydrocarbon molecules. Through spectral fittings of the astronomical spectra of the UIE bands, we show that a significant amount of the energy is emitted by the aliphatic component, implying that aliphatic groups are an essential part of the chemical structure. Arguments in favor of an amorphous, solid-state structure rather than a gas-phase molecule as a carrier of the UIE are also presented.
On a Hydrodynamic Source of Self-Excitation of Narrow-Band Disturbances in a Wind Tunnel
NASA Astrophysics Data System (ADS)
Karavosov, R. K.; Prozorov, A. G.
A study has been made of the occurrence of intense narrow-band components in the spectra of pressure pulsations in a wind tunnel. It has been established that the high level of acoustic emission in auto-oscillations is a consequence of negative static-pressure gradients inside the nozzle and the change in the regime of wall shear flow of an incompressible medium, of the formation of large-scale coherent structures, and of resonance phenomena. It has been noted that the azimuthally nonuniform topology of large-scale transient-flow structures emitting sound and implementation of not a single resonance are responsible for the existence of ensembles of components of an undesirably high level in the pressure-pulsation spectra in the tunnel. One possible method of fighting the considered sound emission generating auto-oscillations has been indicated.
A theory for narrow-banded radio bursts at Uranus - MHD surface waves as an energy driver
NASA Technical Reports Server (NTRS)
Farrell, W. M.; Curtis, S. A.; Desch, M. D.; Lepping, R. P.
A possible scenario for the generation of the narrow-banded radio bursts detected at Uranus by the Voyager 2 planetary radio astronomy experiment is described. In order to account for the emission burstiness which occurs on time scales of hundreds of milliseconds, it is proposed that ULF magnetic surface turbulence generated at the frontside magnetopause propagates down the open/closed field line boundary and mode-converts to kinetic Alfven waves (KAW) deep within the polar cusp. The oscillating KAW potentials then drive a transient electron stream that creates the bursty radio emission. To substantiate these ideas, Voyager 2 magnetometer measurements of enhanced ULF magnetic activity at the frontside magnetopause are shown. It is demonstrated analytically that such magnetic turbulence should mode-convert deep in the cusp at a radial distance of 3 RU.
Narrow band imaging: a new diagnostic approach to visualize angiogenesis in superficial neoplasia.
Muto, Manabu; Katada, Chikatoshi; Sano, Yasushi; Yoshida, Shiegaki
Although numerous gastrointestinal endoscopes pass through the oropharynx and the hypopharynx, it is extremely difficult to detect an early cancer in these sites during routine endoscopic examination. Most patients with cancer in these sites are usually diagnosed in advanced stages. If effective screening methods can detect an earlier stage, such as carcinoma in situ, it would obviously be of great benefit. Narrow band imaging is an innovative optical technology that can clearly visualize the microvascular structure of the organ surface. Herein, we demonstrate that narrow band imaging combined with magnifying endoscopy can identify a carcinoma in situ in oropharyngeal and hypopharyngeal mucosal lesions. Scattered irregular foci of microvascular proliferation projecting to the dysplastic squamous epithelium are the typical features. These results indicate that an approach to visualize angiogenesis or morphologic changes of microvessels in the superficial neoplasm can be a new diagnostic method not only for the head and neck region but also for other sites in the gastrointestinal tract. PMID:16012987
On the theory of error rates for narrow-band digital FM
R. F. Pawula
The theory of error rates for narrow-band digital FM with limiter-discriminator detection and integrate and dump post-detection filtering is considered. The goal is that of simplifying the existing theory, which has evolved primarily in the frequency domain and requires numerical integration and differentiation of Fourier series expansions, numerical convolution, and multibit pattern averaging. A fresh approach in the time domain,
Narrow-band interference filters made from layers of germanium and zinc sulfide
T. N. Maiorova; V. B. Iafaeva; R. A. Nagulina
Narrow-band interference filters intended for use in the middle infrared have been fabricated from germanium and zinc sulfide layers. The filters were prepared in a vacuum chamber at a pressure not exceeding 0.004 Pa and substrate temperatures of 100 and 150 C on substrates consisting of plane-parallel silicon and germanium single-crystal plates. Measurements of the spectral characteristics of filters with
Band gap narrowing in BaTiO{sub 3} nanoparticles facilitated by multiple mechanisms
Ramakanth, S. [Advanced Centre of Research in High Energy Materials (ACRHEM), University of Hyderabad, Hyderabad 500046 (India); James Raju, K. C., E-mail: email@example.com [Advanced Centre of Research in High Energy Materials (ACRHEM), University of Hyderabad, Hyderabad 500046 (India); School of Physics, University of Hyderabad, Hyderabad 500046 (India)
In the present work, BaTiO{sub 3} nanoparticles of four different size ranges were prepared by sol-gel method. The optical band gap of these particles at some size ranges has come down to 2.53?eV from 3.2?eV, resulting in substantial increase in optical absorption by these ferroelectric nanoparticles making them potential candidates for light energy harvesting. XRD results show the presence of higher compressive strain in 23?nm and 54?nm size particles, they exhibit a higher band gap narrowing, whereas tensile strain is observed in 31?nm and 34?nm particles, and they do not show the marginal band gap narrowing. The 23?nm and 54?nm particles also show a coupling of free carriers to phonons by increasing the intensity of LO phonon mode at 715?cm{sup ?1}. The higher surface charge density is expected in case of enhanced surface optical Raman modes (638?cm{sup ?1}) contained in 31 and 34?nm size particles. In addition to this, the red shift in an LO mode Raman spectral line at 305?cm{sup ?1} with decrease in particle size depicts the presence of phonon confinement in it. The enhanced optical absorption in 23?nm and 54?nm size particles with a narrowed band gap of 3?eV and 2.53?eV is due to exchange correlation interactions between the carriers present in these particles. In 31?nm and 34?nm range particles, the absorption got bleached exhibiting increased band gaps of 3.08?eV and 3.2?eV, respectively. It is due to filling up of conduction band resulting from weakening of exchange correlation interactions between the charge carriers. Hence, it is concluded that the band gap narrowing in the nanoparticles of average size 23?nm/54?nm is a consequence of multiple effects like strain, electron-phonon interaction, and exchange correlation interactions between the carriers which is subdued in some other size ranges like 31?nm/34?nm.
The Unidentified Infrared Emission Bands: Identified
NASA Technical Reports Server (NTRS)
Hudgins, Douglas M.; Allamandola, Louis J.; Sandford, Scott A.; Goorvitch, David (Technical Monitor)
The so-called Unidentified Infrared or simply UIR bands, the infrared emission band spectrum associated with a wide variety of interstellar objects, can be modeled in detail by laboratory spectra of neutral and positively charged polycyclic aromatic hydrocarbon (PAH) mixtures. Fits are presented for the UIR emission from the protoplanetary nebula IRAS 22272+5435, the diffuse galactic medium, and the Orion HII/photodissociation front - a selection of objects which span the evolutionary range of interstellar material. These data directly address the spectroscopic criticisms previously leveled at the PAH hypothesis and demonstrate that PAH-related molecular species are indeed responsible for this widespread emission. Furthermore, these fits reflect the structure, abundance, and ionization state of the interstellar PAHs and, in turn, provide direct insight into the processes of carbon nucleation, growth and evolution in circumstellar shells and the interstellar medium. To date, no other candidate material which has been proposed to account for the UIR emission can as readily and specifically reproduce these spectral variations. Given the ubiquity of these species, this work demonstrates the tremendous potential of these species as probes of a new and heretofore largely unexplored facet of astrochemistry - potential which should make PAHs the probe of the next millennium much as CO has been for the last quarter century.
Imaging of the PAH Emission Bands in the Orion Bar
NASA Technical Reports Server (NTRS)
Bregman, Jesse; Harker, David; Rank, David; Temi, Pasqiale; Morrison, David (Technical Monitor)
The infrared spectrum of many planetary nebulae, HII regions, galactic nuclei, reflection nebulae, and WC stars are dominated by a set of narrow and broad features which for many years were called the "unidentified infrared bands". These bands have been attributed to several carbon-rich molecular species which all contain only carbon and hydrogen atoms, and fall into the class of PAH molecules or are conglomerates of PAH skeletons. If these bands are from PAHs, then PAHs contain 1-10% of the interstellar carbon, making them the most abundant molecular species in the interstellar medium after CO. From ground based telescopes, we have studied the emission bands assigned to C-H bond vibrations in PAHs (3.3, 11.3 microns) in the Orion Bar region, and showed that their distribution and intensities are consistent with a quantitative PAH model. We have recently obtained spectral images of the Orion Bar from the KAO at 6.2 and 7.7 microns using a 128 x 128 Si:Ga array camera in order to study the C-C modes of the PAH molecules. We will show these new data along with our existing C-H mode data set, and make a quantitative comparison of the data with the existing PAH model.
Narrow-band search of continuous gravitational-wave signals from Crab and Vela pulsars in Virgo VSR4 data
The LIGO Scientific Collaboration; the Virgo Collaboration; J. Aasi; B. P. Abbott; R. Abbott; T. Abbott; M. R. Abernathy; F. Acernese; K. Ackley; C. Adams; T. Adams; T. Adams; P. Addesso; R. X. Adhikari; V. Adya; C. Affeldt; M. Agathos; K. Agatsuma; N. Aggarwal; O. D. Aguiar; A. Ain; P. Ajith; A. Alemic; B. Allen; A. Allocca; D. Amariutei; S. B. Anderson; W. G. Anderson; K. Arai; M. C. Araya; C. Arceneaux; J. S. Areeda; G. Ashton; S. Ast; S. M. Aston; P. Astone; P. Aufmuth; C. Aulbert; B. E. Aylott; S. Babak; P. T. Baker; F. Baldaccini; G. Ballardin; S. W. Ballmer; J. C. Barayoga; M. Barbet; S. Barclay; B. C. Barish; D. Barker; F. Barone; B. Barr; L. Barsotti; M. Barsuglia; J. Bartlett; M. A. Barton; I. Bartos; R. Bassiri; A. Basti; J. C. Batch; Th. S. Bauer; C. Baune; V. Bavigadda; B. Behnke; M. Bejger; C. Belczynski; A. S. Bell; C. Bell; M. Benacquista; J. Bergman; G. Bergmann; C. P. L. Berry; D. Bersanetti; A. Bertolini; J. Betzwieser; S. Bhagwat; R. Bhandare; I. A. Bilenko; G. Billingsley; J. Birch; S. Biscans; M. Bitossi; C. Biwer; M. A. Bizouard; J. K. Blackburn; L. Blackburn; C. D. Blair; D. Blair; S. Bloemen; O. Bock; T. P. Bodiya; M. Boer; G. Bogaert; P. Bojtos; C. Bond; F. Bondu; L. Bonelli; R. Bonnand; R. Bork; M. Born; V. Boschi; Sukanta Bose; C. Bradaschia; P. R. Brady; V. B. Braginsky; M. Branchesi; J. E. Brau; T. Briant; D. O. Bridges; A. Brillet; M. Brinkmann; V. Brisson; A. F. Brooks; D. A. Brown; D. D. Brown; N. M. Brown; S. Buchman; A. Buikema; T. Bulik; H. J. Bulten; A. Buonanno; D. Buskulic; C. Buy; L. Cadonati; G. Cagnoli; J. Calder¾n Bustillo; E. Calloni; J. B. Camp; K. C. Cannon; J. Cao; C. D. Capano; F. Carbognani; S. Caride; S. Caudill; M. CavagliÓ; F. Cavalier; R. Cavalieri; G. Cella; C. Cepeda; E. Cesarini; R. Chakraborty; T. Chalermsongsak; S. J. Chamberlin; S. Chao; P. Charlton; E. Chassande-Mottin; Y. Chen; A. Chincarini; A. Chiummo; H. S. Cho; M. Cho; J. H. Chow; N. Christensen; Q. Chu; S. Chua; S. Chung; G. Ciani; F. Clara; J. A. Clark; F. Cleva; E. Coccia; P. -F. Cohadon; A. Colla; C. Collette; M. Colombini; L. Cominsky; M. Constancio, Jr.; A. Conte; D. Cook; T. R. Corbitt; N. Cornish; A. Corsi; C. A. Costa; M. W. Coughlin; J. -P. Coulon; S. Countryman; P. Couvares; D. M. Coward; M. J. Cowart; D. C. Coyne; R. Coyne; K. Craig; J. D. E. Creighton; T. D. Creighton; J. Cripe; S. G. Crowder; A. Cumming; L. Cunningham; E. Cuoco; C. Cutler; K. Dahl; T. Dal Canton; M. Damjanic; S. L. Danilishin; S. D'Antonio; K. Danzmann; L. Dartez; V. Dattilo; I. Dave; H. Daveloza; M. Davier; G. S. Davies; E. J. Daw; R. Day; D. DeBra; G. Debreczeni; J. Degallaix; M. De Laurentis; S. Delķglise; W. Del Pozzo; T. Denker; T. Dent; H. Dereli; V. Dergachev; R. De Rosa; R. T. DeRosa; R. DeSalvo; S. Dhurandhar; M. DĒaz; L. Di Fiore; A. Di Lieto; I. Di Palma; A. Di Virgilio; G. Dojcinoski; V. Dolique; E. Dominguez; F. Donovan; K. L. Dooley; S. Doravari; R. Douglas; T. P. Downes; M. Drago; J. C. Driggers; Z. Du; M. Ducrot; S. Dwyer; T. Eberle; T. Edo; M. Edwards; M. Edwards; A. Effler; H. -B. Eggenstein; P. Ehrens; J. Eichholz; S. S. Eikenberry; R. Essick; T. Etzel; M. Evans; T. Evans; M. Factourovich; V. Fafone; S. Fairhurst; X. Fan; Q. Fang; S. Farinon; B. Farr; W. M. Farr; M. Favata; M. Fays; H. Fehrmann; M. M. Fejer; D. Feldbaum; I. Ferrante; E. C. Ferreira; F. Ferrini; F. Fidecaro; I. Fiori; R. P. Fisher; R. Flaminio; J. -D. Fournier; S. Franco; S. Frasca; F. Frasconi; Z. Frei; A. Freise; R. Frey; T. T. Fricke; P. Fritschel; V. V. Frolov; S. Fuentes-Tapia; P. Fulda; M. Fyffe; J. R. Gair; L. Gammaitoni; S. Gaonkar; F. Garufi; A. Gatto; N. Gehrels; G. Gemme; B. Gendre; E. Genin; A. Gennai; L. ┴. Gergely; S. Ghosh; J. A. Giaime; K. D. Giardina; A. Giazotto; J. Gleason; E. Goetz; R. Goetz; L. Gondan; G. Gonzßlez; N. Gordon; M. L. Gorodetsky; S. Gossan; S. Go▀ler; R. Gouaty; C. Grõf; P. B. Graff; M. Granata; A. Grant; S. Gras; C. Gray; G. Greco; R. J. S. Greenhalgh; A. M. Gretarsson; P. Groot; H. Grote; S. Grunewald; G. M. Guidi; C. J. Guido; X. Guo; K. Gushwa; E. K. Gustafson; R. Gustafson; J. Hacker; E. D. Hall; G. Hammond; M. Hanke; J. Hanks; C. Hanna; M. D. Hannam; J. Hanson; T. Hardwick; J. Harms; G. M. Harry; I. W. Harry; M. Hart; M. T. Hartman; C. -J. Haster; K. Haughian; S. Hee; A. Heidmann; M. Heintze; G. Heinzel; H. Heitmann; P. Hello; G. Hemming; M. Hendry; I. S. Heng; A. W. Heptonstall; M. Heurs; M. Hewitson; S. Hild; D. Hoak; K. A. Hodge; D. Hofman; S. E. Hollitt; K. Holt; P. Hopkins; D. J. Hosken; J. Hough; E. Houston; E. J. Howell; Y. M. Hu; E. Huerta; B. Hughey; S. Husa; S. H. Huttner; M. Huynh; T. Huynh-Dinh; A. Idrisy; N. Indik; D. R. Ingram; R. Inta; G. Islas; J. C. Isler; T. Isogai; B. R. Iyer; K. Izumi; M. Jacobson; H. Jang; P. Jaranowski; S. Jawahar; Y. Ji; F. Jimķnez-Forteza; W. W. Johnson; D. I. Jones; R. Jones; R. J. G. Jonker; L. Ju; Haris K
In this paper we present the results of a coherent narrow-band search for continuous gravitational-wave signals from the Crab and Vela pulsars conducted on Virgo VSR4 data. In order to take into account a possible small mismatch between the gravitational wave frequency and two times the star rotation frequency, inferred from measurement of the electromagnetic pulse rate, a range of 0.02 Hz around two times the star rotational frequency has been searched for both the pulsars. No evidence for a signal has been found and 95$\\%$ confidence level upper limits have been computed both assuming polarization parameters are completely unknown and that they are known with some uncertainty, as derived from X-ray observations of the pulsar wind torii. For Vela the upper limits are comparable to the spin-down limit, computed assuming that all the observed spin-down is due to the emission of gravitational waves. For Crab the upper limits are about a factor of two below the spin-down limit, and represent a significant improvement with respect to past analysis. This is the first time the spin-down limit is significantly overcome in a narrow-band search.
Narrow-band search of continuous gravitational-wave signals from Crab and Vela pulsars in Virgo VSR4 data
NASA Astrophysics Data System (ADS)
Aasi, J.; Abbott, B. P.; Abbott, R.; Abbott, T.; Abernathy, M. R.; Acernese, F.; Ackley, K.; Adams, C.; Adams, T.; Adams, T.; Addesso, P.; Adhikari, R. X.; Adya, V.; Affeldt, C.; Agathos, M.; Agatsuma, K.; Aggarwal, N.; Aguiar, O. D.; Ain, A.; Ajith, P.; Alemic, A.; Allen, B.; Allocca, A.; Amariutei, D.; Anderson, S. B.; Anderson, W. G.; Arai, K.; Araya, M. C.; Arceneaux, C.; Areeda, J. S.; Ashton, G.; Ast, S.; Aston, S. M.; Astone, P.; Aufmuth, P.; Aulbert, C.; Aylott, B. E.; Babak, S.; Baker, P. T.; Baldaccini, F.; Ballardin, G.; Ballmer, S. W.; Barayoga, J. C.; Barbet, M.; Barclay, S.; Barish, B. C.; Barker, D.; Barone, F.; Barr, B.; Barsotti, L.; Barsuglia, M.; Bartlett, J.; Barton, M. A.; Bartos, I.; Bassiri, R.; Basti, A.; Batch, J. C.; Bauer, Th. S.; Baune, C.; Bavigadda, V.; Behnke, B.; Bejger, M.; Belczynski, C.; Bell, A. S.; Bell, C.; Benacquista, M.; Bergman, J.; Bergmann, G.; Berry, C. P. L.; Bersanetti, D.; Bertolini, A.; Betzwieser, J.; Bhagwat, S.; Bhandare, R.; Bilenko, I. A.; Billingsley, G.; Birch, J.; Biscans, S.; Bitossi, M.; Biwer, C.; Bizouard, M. A.; Blackburn, J. K.; Blackburn, L.; Blair, C. D.; Blair, D.; Bloemen, S.; Bock, O.; Bodiya, T. P.; Boer, M.; Bogaert, G.; Bojtos, P.; Bond, C.; Bondu, F.; Bonelli, L.; Bonnand, R.; Bork, R.; Born, M.; Boschi, V.; Bose, Sukanta; Bradaschia, C.; Brady, P. R.; Braginsky, V. B.; Branchesi, M.; Brau, J. E.; Briant, T.; Bridges, D. O.; Brillet, A.; Brinkmann, M.; Brisson, V.; Brooks, A. F.; Brown, D. A.; Brown, D. D.; Brown, N. M.; Buchman, S.; Buikema, A.; Bulik, T.; Bulten, H. J.; Buonanno, A.; Buskulic, D.; Buy, C.; Cadonati, L.; Cagnoli, G.; Calder¾n Bustillo, J.; Calloni, E.; Camp, J. B.; Cannon, K. C.; Cao, J.; Capano, C. D.; Carbognani, F.; Caride, S.; Caudill, S.; CavagliÓ, M.; Cavalier, F.; Cavalieri, R.; Cella, G.; Cepeda, C.; Cesarini, E.; Chakraborty, R.; Chalermsongsak, T.; Chamberlin, S. J.; Chao, S.; Charlton, P.; Chassande-Mottin, E.; Chen, Y.; Chincarini, A.; Chiummo, A.; Cho, H. S.; Cho, M.; Chow, J. H.; Christensen, N.; Chu, Q.; Chua, S.; Chung, S.; Ciani, G.; Clara, F.; Clark, J. A.; Cleva, F.; Coccia, E.; Cohadon, P.-F.; Colla, A.; Collette, C.; Colombini, M.; Cominsky, L.; Constancio, M.; Conte, A.; Cook, D.; Corbitt, T. R.; Cornish, N.; Corsi, A.; Costa, C. A.; Coughlin, M. W.; Coulon, J.-P.; Countryman, S.; Couvares, P.; Coward, D. M.; Cowart, M. J.; Coyne, D. C.; Coyne, R.; Craig, K.; Creighton, J. D. E.; Creighton, T. D.; Cripe, J.; Crowder, S. G.; Cumming, A.; Cunningham, L.; Cuoco, E.; Cutler, C.; Dahl, K.; Canton, T. Dal; Damjanic, M.; Danilishin, S. L.; D'Antonio, S.; Danzmann, K.; Dartez, L.; Dattilo, V.; Dave, I.; Daveloza, H.; Davier, M.; Davies, G. S.; Daw, E. J.; Day, R.; DeBra, D.; Debreczeni, G.; Degallaix, J.; De Laurentis, M.; Delķglise, S.; Del Pozzo, W.; Denker, T.; Dent, T.; Dereli, H.; Dergachev, V.; De Rosa, R.; DeRosa, R. T.; DeSalvo, R.; Dhurandhar, S.; DĒaz, M.; Di Fiore, L.; Di Lieto, A.; Di Palma, I.; Di Virgilio, A.; Dojcinoski, G.; Dolique, V.; Dominguez, E.; Donovan, F.; Dooley, K. L.; Doravari, S.; Douglas, R.; Downes, T. P.; Drago, M.; Driggers, J. C.; Du, Z.; Ducrot, M.; Dwyer, S.; Eberle, T.; Edo, T.; Edwards, M.; Edwards, M.; Effler, A.; Eggenstein, H.-B.; Ehrens, P.; Eichholz, J.; Eikenberry, S. S.; Essick, R.; Etzel, T.; Evans, M.; Evans, T.; Factourovich, M.; Fafone, V.; Fairhurst, S.; Fan, X.; Fang, Q.; Farinon, S.; Farr, B.; Farr, W. M.; Favata, M.; Fays, M.; Fehrmann, H.; Fejer, M. M.; Feldbaum, D.; Ferrante, I.; Ferreira, E. C.; Ferrini, F.; Fidecaro, F.; Fiori, I.; Fisher, R. P.; Flaminio, R.; Fournier, J.-D.; Franco, S.; Frasca, S.; Frasconi, F.; Frei, Z.; Freise, A.; Frey, R.; Fricke, T. T.; Fritschel, P.; Frolov, V. V.; Fuentes-Tapia, S.; Fulda, P.; Fyffe, M.; Gair, J. R.; Gammaitoni, L.; Gaonkar, S.; Garufi, F.; Gatto, A.; Gehrels, N.; Gemme, G.; Gendre, B.; Genin, E.; Gennai, A.; Gergely, L. ┴.; Ghosh, S.; Giaime, J. A.; Giardina, K. D.; Giazotto, A.; Gleason, J.; Goetz, E.; Goetz, R.; Gondan, L.; Gonzßlez, G.; Gordon, N.; Gorodetsky, M. L.; Gossan, S.; Go▀ler, S.; Gouaty, R.; Grõf, C.; Graff, P. B.; Granata, M.; Grant, A.; Gras, S.; Gray, C.; Greco, G.; Greenhalgh, R. J. S.; Gretarsson, A. M.; Groot, P.; Grote, H.; Grunewald, S.; Guidi, G. M.; Guido, C. J.; Guo, X.; Gushwa, K.; Gustafson, E. K.; Gustafson, R.; Hacker, J.; Hall, E. D.; Hammond, G.; Hanke, M.; Hanks, J.; Hanna, C.; Hannam, M. D.; Hanson, J.; Hardwick, T.; Harms, J.; Harry, G. M.; Harry, I. W.; Hart, M.; Hartman, M. T.; Haster, C.-J.; Haughian, K.; Hee, S.; Heidmann, A.; Heintze, M.; Heinzel, G.; Heitmann, H.; Hello, P.; Hemming, G.; Hendry, M.; Heng, I. S.; Heptonstall, A. W.; Heurs, M.; Hewitson, M.; Hild, S.; Hoak, D.; Hodge, K. A.; Hofman, D.; Hollitt, S. E.; Holt, K.; Hopkins, P.; Hosken, D. J.; Hough, J.; Houston, E.
In this paper we present the results of a coherent narrow-band search for continuous gravitational-wave signals from the Crab and Vela pulsars conducted on Virgo VSR4 data. In order to take into account a possible small mismatch between the gravitational-wave frequency and two times the star rotation frequency, inferred from measurement of the electromagnetic pulse rate, a range of 0.02 Hz around two times the star rotational frequency has been searched for both the pulsars. No evidence for a signal has been found and 95% confidence level upper limits have been computed assuming both that polarization parameters are completely unknown and that they are known with some uncertainty, as derived from x-ray observations of the pulsar wind torii. For Vela the upper limits are comparable to the spin-down limit, computed assuming that all the observed spin-down is due to the emission of gravitational waves. For Crab the upper limits are about a factor of 2 below the spin-down limit, and represent a significant improvement with respect to past analysis. This is the first time the spin-down limit is significantly overcome in a narrow-band search.
EVOLUTION OF [O III] {lambda}5007 EMISSION-LINE PROFILES IN NARROW EMISSION-LINE GALAXIES
Wang, J.; Mao, Y. F.; Wei, J. Y., E-mail: email@example.com [National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100021 (China)
The active galactic nucleus (AGN)-host co-evolution issue is investigated here by focusing on the evolution of the [O III] {lambda}5007 emission-line profile. A large sample of narrow emission-line galaxies is selected from the Max-Planck Institute for Astrophysics/Johns Hopkins University Sloan Digital Sky Survey DR7 catalog to simultaneously measure both the [O III] line profile and circumnuclear stellar population in an individual spectrum. By requiring that (1) the [O III] line signal-to-noise ratio is larger than 30 and (2) the [O III] line width is larger than the instrumental resolution by a factor of two, our sample is narrowed down to 2333 Seyfert galaxies/LINERs (AGNs), 793 transition galaxies, and 190 star-forming galaxies. In addition to the commonly used profile parameters (i.e., line centroid, relative velocity shift, and velocity dispersion), two dimensionless shape parameters, skewness and kurtosis, are used to quantify the line shape deviation from a pure Gaussian function. We show that the transition galaxies are systematically associated with narrower line widths and weaker [O III] broad wings than the AGNs, which implies that the kinematics of emission-line gas are different in the two kinds of objects. By combining the measured host properties and line shape parameters, we find that the AGNs with stronger blue asymmetries tend to be associated with younger stellar populations. However, a similar trend is not identified in the transition galaxies. The failure likely results from a selection effect in which the transition galaxies are systematically associated with younger stellar populations than the AGNs. The evolutionary significance revealed here suggests that both narrow-line region kinematics and outflow feedback in AGNs co-evolve with their host galaxies.
High open circuit voltage in regioregular narrow band gap polymer solar cells.
Wang, Ming; Wang, Hengbin; Yokoyama, Takamichi; Liu, Xiaofeng; Huang, Ye; Zhang, Yuan; Nguyen, Thuc-Quyen; Aramaki, Shinji; Bazan, Guillermo C
The regioregular narrow band gap (E(g) ~1.5 eV) conjugated polymer PIPCP was designed and synthesized. PIPCP contains a backbone comprised of CPDT-PT-IDT-PT repeat units (CPDT = cyclopentadithiophene, PT = pyridyl[2,1,3]thiadiazole, IDT = indacenodithiophene) and strictly organized PT orientations, such that the pyridyl N-atoms point toward the CPDT fragment. Comparison of PIPCP with the regiorandom counterpart PIPC-RA illustrates that the higher level of molecular order translates to higher power conversion efficiencies (PCEs) when incorporated into bulk heterojunction (BHJ) organic solar cells. Examination of thin films via absorption spectroscopy and grazing incidence wide-angle X-ray diffraction (GIWAXS) experiments provides evidence of higher order within thin films obtained by spin coating. Most significantly, we find that PIPCP:PC61BM blends yield devices with an open circuit voltage (V(oc)) of 0.86 V, while maintaining a PCE of ~6%. Comparison against a wide range of analogous narrow band gap conjugated polymers reveals that this V(oc) value is particularly high for a BHJ system with band gaps in the 1.4-1.5 eV range thereby indicating a very low E(g) - eV(oc) loss. PMID:25122541
Study of the X-ray emission mechanism of radio-loud narrow-line Seyfert 1 galaxy
Shirakawa, H; Tanaka, Y; Itoh, R; Kawaguchi, K
1H0323+342 is one of narrow-line radio-loud Seyfert 1 galaxies (RL-NLS1), which is a new class of gamma-ray emitting AGNs. Narrow-line Seyfert 1 galaxies (NLS1) have a small-mass black hole, but its mass accretion rate is almost as high as Eddington limit. Therefore, by observing NLS1s, we can know the evolution of supermassive black holes at the center of galaxies. Some of NLS1s are radio-loud and we call them RL-NLS1. From past observations, multi-wavelength spectrum of RL-NLS1s is similar to that of typical blazars; the synchrotron emission in the lower energy band up to the optical band, and inverse Compton scattering of low energy photons from disk, torus, and broad line region. X-ray band is a transittion region between the synchrotron and inverse Compton, and also there is a possible disk/corona emission. Therefore, we studied the energy-dependence of time variability of the X-ray emission of 1H0323+342, which have been observed by Suzaku in 2009 and 2013, in order to constrain the emission mechanism. ...
Narrow band filter using 1D periodic structure with defects for DWDM systems
NASA Astrophysics Data System (ADS)
Ghosh, R.; Ghosh, K. K.; Chakraborty, R.
A 1D binary periodic structure with defect has been analysed using Transfer Matrix Method. For a particular nine layered structure of SiO2 and InP, a number of full stop bands (in other words, zero passbands or forbidden bands) at different regions of the spectrum under investigation are observed. Introducing a central spatial defect in the system by adjusting the layer width, it is possible to achieve an extremely narrow passband centred on 1554.9 nm in the 7th forbidden band. Moreover by varying the defect width, the number of passbands can be increased. These passbands have flat and 100% stopband and hence can be better candidate to drop single or multiple frequencies in WDM systems. It is further observed that with increase in the number of layers and/or defect width, the number of mini pass bands outside the original forbidden band also increases. Also by FDTD simulation it is seen that the field is localised within the defect for the passband frequency.
A search for double-peaked narrow emission line galaxies and AGNs in the LAMOST DR1
NASA Astrophysics Data System (ADS)
Shi, Zhi-Xin; Luo, A.-Li; Comte, Georges; Chen, Xiao-Yan; Wei, Peng; Zhao, Yong-Heng; Wu, Fu-Chao; Zhang, Yan-Xia; Shen, Shi-Yin; Yang, Ming; Wu, Hong; Wu, Xue-Bing; Zhang, Hao-Tong; Lei, Ya-Juan; Zhang, Jian-Nan; Wang, Ting-Gui; Jin, Ge; Zhang, Yong
The Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) has released more than two million spectra, which provide the opportunity to search for double-peaked narrow emission line (NEL) galaxies and active galactic nuclei (AGNs). The double-peaked narrow-line profiles can be well modeled by two velocity components, respectively blueshifted and redshifted with respect to the systemic recession velocity. This paper presents 20 double-peaked NEL galaxies and AGNs found from LAMOST DR1 using a search method based on a multi-Gaussian fit of the narrow emission lines. Among them, ten have already been published by other authors, either listed as genuine double-peaked NEL objects or as asymmetric NEL objects, and the remaining ten are original discoveries. We discuss some possible origins for the double-peaked narrow-line features, such as interaction between jet and narrow line regions, interaction with companion galaxies, and black hole binaries. Spatially resolved optical imaging and/or follow-up observations in other spectral bands are needed to further discuss the physical mechanisms at work.
A simplified scheme for generating narrow-band mid-ultraviolet laser radiation
NASA Astrophysics Data System (ADS)
Almog, G.; Scholz, M.; Weber, W.; Leisching, P.; Kaenders, W.; Udem, Th.
We report on the development and characterization of continuous, narrow-band, and tunable laser systems that use direct second-harmonic generation from blue and green diode lasers with an output power level of up to 11.1 mW in the mid-ultraviolet. One of our laser systems was tuned to the mercury 61S0 ? 63P1 intercombination line at 253.7 nm. We could perform Doppler-free saturation spectroscopy on this line and were able to lock our laser to the transition frequency on long time scales.
A simplified scheme for generating narrow-band mid-ultraviolet laser radiation.
Almog, G; Scholz, M; Weber, W; Leisching, P; Kaenders, W; Udem, Th
We report on the development and characterization of continuous, narrow-band, and tunable laser systems that use direct second-harmonic generation from blue and green diode lasers with an output power level of up to 11.1 mW in the mid-ultraviolet. One of our laser systems was tuned to the mercury 6(1)S0 ? 6(3)P1 intercombination line at 253.7 nm. We could perform Doppler-free saturation spectroscopy on this line and were able to lock our laser to the transition frequency on long time scales. PMID:25832214
Construction of narrow-band regenerative amplifier for momentum imaging spectroscopy of lithium dimer
Matsuoka, Leo; Hashimoto, Masashi; Yokoyama, Keiichi [Quantum Beam Science Directorate, Japan Atomic Energy Agency, 8-1-7, Umemidai, Kizugawa, Kyoto 619-0215 (Japan)
We constructed a Ti:Sapphire narrow-band regenerative amplifier as the probe laser of the experiment of momentum imaging spectroscopy of lithium dimer. The spectral profile of the regenerative cavity was designed by three birefringent filters and a plate of etalon. With 1.1-mJ pumping by the second harmonics of Nd:YLF laser, mode-locked seed pulses were amplified to {approx}25 {mu}J at 1-kHz repetition, with the bandwidth of {approx}0.7 cm{sup -1}.
Narrow band imaging for detecting superficial oral squamous cell carcinoma: a report of two cases.
Katada, Chikatoshi; Nakayama, Meijin; Tanabe, Satoshi; Naruke, Akira; Koizumi, Wasaburo; Masaki, Takashi; Okamoto, Makito; Saigenji, Katsunori
We present two cases of superficial squamous cell carcinoma of the floor of the mouth, which were coincidentally detected by narrow band imaging (NBI) combined with magnifying gastrointestinal endoscopy (GIE) during gastrointestinal evaluation. We successfully removed the lesions using laser assisted with NBI combined with magnifying GIE. Because NBI combined with magnifying GIE shows a well-demarcated brownish area and scattered foci of microvascular proliferation, it may play an important role in the management of superficial squamous cell carcinoma in the oral cavity. PMID:17597626
On-sky characterisation of the VISTA NB118 narrow-band filters at 1.19 ?m
NASA Astrophysics Data System (ADS)
Milvang-Jensen, Bo; Freudling, Wolfram; Zabl, Johannes; Fynbo, Johan P. U.; M°ller, Palle; Nilsson, Kim K.; McCracken, Henry Joy; Hjorth, Jens; Le FĶvre, Olivier; Tasca, Lidia; Dunlop, James S.; Sobral, David
Observations of the high redshift Universe through narrow-band filters have proven very successful in the last decade. The 4-m VISTA telescope, equipped with the wide-field camera VIRCAM, offers a major step forward in wide-field near-infrared imaging, and in order to utilise VISTA's large field-of-view and sensitivity, the Dark Cosmology Centre provided a set of 16 narrow-band filters for VIRCAM. These NB118 filters are centered at a wavelength near 1.19 ?m in a region with few airglow emission lines. The filters allow the detection of H? emitters at z = 0.8, H? and [O iii] emitters at z ? 1.4, [O ii] emitters at z = 2.2, and Ly? emitters at z = 8.8. Based on guaranteed time observations of the COSMOS field we here present a detailed description and characterization of the filters and their performance. In particular we provide sky-brightness levels and depths for each of the 16 detector/filter sets and find that some of the filters show signs of some red-leak. We identify a sample of 2 ū 103 candidate emission-line objects in the data. Cross-correlating this sample with a large set of galaxies with known spectroscopic redshifts we determine the "in situ" passbands of the filters and find that they are shifted by about 3.5 - 4 nm (corresponding to 30% of the filter width) to the red compared to the expectation based on the laboratory measurements. Finally, we present an algorithm to mask out persistence in VIRCAM data. Scientific results extracted from the data will be presented separately. Based on observations collected at the European Southern Observatory, Chile, as part of programme 284.A-5026 (VISTA NB118 GTO, PI Fynbo) and 179.A-2005 (UltraVISTA, PIs Dunlop, Franx, Fynbo, & Le FĶvre).
Locata Performance Evaluation in the Presence of Wide- and Narrow-Band Interference
NASA Astrophysics Data System (ADS)
Khan, Faisal A.; Rizos, Chris; Dempster, Andrew G.
Classically difficult positioning environments often call for augmentation technology to assist the GPS, or more generally the Global Navigation Satellite System (GNSS) technology. The ground-based ranging technology offers augmentation, and even replacement, to GPS in such environments. However, like any other system relying on wireless technology, a Locata positioning network also faces issues in the presence of RF interference (RFI). This problem is magnified due to the fact that Locata operates in the licence-free 2Ę4 GHz Industrial, Scientific and Medical (ISM) band. The licence-free nature of this band attracts a much larger number of devices using a wider range of signal types than for licensed bands, resulting in elevation of the noise floor. Also, harmonics from out-of-band signals can act as potential interferers. WiFi devices operating in this band have been identified as the most likely potential interferer, due partially to their use of the whole ISM band, but also because Locata applications often also may use a wireless network. This paper evaluates the performance of Locata in the presence of both narrow- and wide-band interfering signals. Effects of received interference on both raw measurements and final solutions are reported and analysed. Test results show that Locata performance degrades in the presence of received interference. It is also identified that high levels of received interference can affect Locata carriers even if the interference is not in co-frequency situation with the affected carrier. Finally, Locata characteristics have been identified which can be exploited to mitigate RFI issues.
Electrically driven, narrow-linewidth blackbody emission from carbon nanotube microcavity devices
NASA Astrophysics Data System (ADS)
Fujiwara, M.; Tsuya, D.; Maki, H.
We report electrically driven narrow-linewidth blackbody emission from carbon-nanotube with Fabry-Perot microcavities. We fabricated two types of devices with microcavities consisting of either gold mirrors or distributed Bragg reflectors (DBR). Gold-mirror microcavity devices exhibit blackbody emission with narrowed full-width at half-maximum of ś50 nm in contrast to the broad normal blackbody emission spectrum. The spectra from these devices can be explained by theoretical calculations accounting for the temperature-dependent intrinsic blackbody spectra and transmittance spectrum of the microcavity. Moreover, the DBR microcavity devices show a narrower resonant peak inside the photonic bandgap, compared with the gold-mirror microcavity device.
Narrow band wavelength selective filter using grating assisted single ring resonator
Prabhathan, P., E-mail: email@example.com; Murukeshan, V. M. [Centre for Optical and Laser Engineering (COLE), School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore)
This paper illustrates a filter configuration which uses a single ring resonator of larger radius connected to a grating resonator at its drop port to achieve single wavelength selectivity and switching property with spectral features suitable for on-chip wavelength selection applications. The proposed configuration is expected to find applications in silicon photonics devices such as, on-chip external cavity lasers and multi analytic label-free biosensors. The grating resonator has been designed for a high Q-factor, high transmittivity, and minimum loss so that the wavelength selectivity of the device is improved. The proof-of-concept device has been demonstrated on a Silicon-on-Insulator (SOI) platform through electron beam lithography and Reactive Ion Etching (RIE) process. The transmission spectrum shows narrow band single wavelength selection and switching property with a high Free Spectral Range (FSR) ?60 nm and side band rejection ratio >15 dB.
A search for narrow band signals with SERENDIP II: a progress report
NASA Technical Reports Server (NTRS)
Werthimer, D.; Brady, R.; Berezin, A.; Bowyer, S.
Commensal programs for the Search for Extraterrestrial Intelligence (SETI), carried out concurrently with conventional radio astronomical observing programs, can be an attractive and cost-effective means of exploring the large multidimensional search space intrinsic to this effort. Our automated commensal system, SERENDIP II, is a high resolution 131,072 channel spectrometer. It searches for 0.49 Hz signals in sequential 64,700 Hz bands of the IF signal from a radio telescope being used for an astronomical observation. Upon detection of a narrow band signal with power above a preset threshold, the frequency, power, time, and telescope direction are recorded for later study. The system has been tested at the Hat Creek Radio Astronomy Observatory 85 ft telescope and the NASA-JPL Deep Space Station (DSS 14) 64 m telescope. It is currently collecting data at the National Radio Astronomy Observatory 300 ft telescope.
In vivo early diagnosis of gastric dysplasia using narrow-band image-guided Raman endoscopy
NASA Astrophysics Data System (ADS)
Huang, Zhiwei; Bergholt, Mads Sylvest; Zheng, Wei; Lin, Kan; Ho, Khek Yu; Teh, Ming; Yeoh, Khay Guan
We first report on the implementation of a novel narrow-band image-guided Raman endoscopy technique for in vivo diagnosis of gastric dysplasia. High-quality in vivo Raman spectra can be acquired from normal and dysplastic gastric mucosal tissue within 0.5 sec under narrow-band image (NBI) guidance at gastroscopy. Significant differences are observed in in vivo Raman spectra between normal (n=54) and dysplastic (n=18) gastric tissue from 30 gastric patients, particularly in the spectral ranges of 825 to 950, 1000 to 1100, 1250 to 1500, and 1600 to 1800 cm-1, which primarily contain signals related to proteins, nucleic acids, and lipids. The multivariate analysis [i.e., principal components analysis (PCA) and linear discriminant analysis (LDA)], together with the leave-one tissue site-out, cross validation on in vivo gastric Raman spectra yields a diagnostic sensitivity of 94.4% (17/18) and specificity of 96.3% (52/54) for distinction of gastric dysplastic tissue. This study suggests that narrowband image-guided Raman endoscopy associated with PCA-LDA diagnostic algorithms has potential for the noninvasive, in vivo early diagnosis and detection of gastric precancer during clinical gastroscopic examination.
Narrow-band N-resonance formed in thin rubidium atomic layers
Sargsyan, A.; Mirzoyan, R.; Sarkisyan, D., E-mail: firstname.lastname@example.com [National Academy of Sciences of Armenia, Institute for Physical Research (Armenia)
The narrow-band N-resonance formed in a {Lambda} system of D{sub 1}-line rubidium atoms is studied in the presence of a buffer gas (neon) and the radiations of two continuous narrow-band diode lasers. Special-purpose cells are used to investigate the dependence of the process on vapor column thickness L in millimeter, micrometer, and nanometer ranges. A comparison of the dependences of the N-resonance and the electromagnetically induced transparency (EIT) resonance on L demonstrates that the minimum (record) thickness at which the N-resonance can be detected is L = 50 {mu}m and that a high-contrast EIT resonance can easily be formed even at L Almost-Equal-To 800 nm. The N-resonance in a magnetic field for {sup 85}Rb atoms is shown to split into five or six components depending on the magnetic field and laser radiation directions. The results obtained indicate that levels F{sub g} = 2, 3 are initial and final in the N-resonance formation. The dependence of the N-resonance on the angle between the laser beams is analyzed, and practical applications are noted.
Energy spectra of \\textbf{2D} gravity and capillary waves with narrow frequency band excitation
Elena Kartashova
In this Letter we present a new method, called chain equation method (CEM), for computing a cascade of distinct modes in a two-dimensional weakly nonlinear wave system generated by narrow frequency band excitation. The CEM is a means for computing the quantized energy spectrum as an explicit function of frequency $\\o_0$ and stationary amplitude $A_0$ of excitation. The physical mechanism behind the generation of the quantized cascade is modulation instability. The CEM can be used in numerous \\textbf{2D} weakly nonlinear wave systems with narrow frequency band excitation appearing in hydrodynamics, nonlinear optics, electrodynamics, convection theory etc. In this Letter the CEM is demonstrated with examples of gravity and capillary waves with dispersion functions $\\o(k) \\sim k^{1/2}$ and $\\o(k) \\sim k^{3/2}$ respectively, and for two different levels of nonlinearity $\\eps=A_0k_0$: small ($\\eps\\sim 0.1$ to 0.25) and moderate ($\\eps\\sim 0.25$ to 0.4).
Nature of the narrow optical band in H*-aggregates: Dozy-chaos-exciton coupling
NASA Astrophysics Data System (ADS)
Egorov, Vladimir V.
Dozy chaos emerges as a combined effect of the collective chaotic motion of electrons and nuclei, and their chaotic electromagnetic interactions in the transient state of molecules experiencing quantum transitions. Following earlier discussions of the well-known Br÷nsted relations for proton-transfer reactions; the temperature-dependent electron transfer in Langmuir-Blodgett films; the shape of the optical bands of polymethine dye monomers, their dimers, and J-aggregates, this paper reports one more application of the dozy-chaos theory of molecular quantum transitions. The qualitative and quantitative explanations for shape of a narrow and blue-shifted optical absorption band in H*-aggregates is given on the basis of the dozy-chaos theory by taking into account the dozy-chaos-exciton coupling effect. It is emphasized that in the H*-aggregate chromophore (dimer of cyclic bis-thiacarbocyanines) there is a competition between two Frenkel exciton transitions through the chaotic reorganization motion of nuclear environment. As a result, the highly organized quantum transition to the upper exciton state becomes an exciton-induced source of dozy chaos for the low organized transition to the lower exciton state. This manifests itself in appearing the narrow peak and broad wing in the optical spectrum pattern of H*-aggregates. A similar enhancement in the H*-effect caused by the strengthening of the exciton coupling in H*-dimers, which could be achieved by synthesizing tertiary and quarternary thiacarbocyanine monomers, is predicted.
The effect of timing noise on targeted and narrow-band coherent searches for continuous gravitational waves
G. Ashton; D. I. Jones; R. Prix
Most continuous gravitational-wave searches use Taylor expansions in the phase to model the spindown of neutron stars. Studies of pulsars demonstrate that their electromagnetic (EM) emissions suffer from timing noise, small deviations in the phase from Taylor expansion models. How the mechanism producing EM emission is related to any continuous gravitational-wave (CW) emission is unknown; if they either interact or are locked in phase then the CW will also experience timing noise. Any disparity between the signal and the search template used in matched filtering methods will result in a loss of signal-to-noise ratio (SNR), referred to as 'mismatch'. In this work we assume the CW suffers a similar level of timing noise to its EM counterpart. We inject and recover fake CW signals, which include timing noise generated from observational data on the Crab pulsar. Measuring the mismatch over durations of order ~ 10 months, the effect is for the most part found to be small. This suggests recent so-called 'narrow-band' searches which placed upper limits on the signals from the Crab and Vela pulsars will not be significantly affected. At a fixed observation time, we find the mismatch depends upon the observation epoch. Considering the averaged mismatch as a function of observation time, we find that it increases as a power law with time, and so may become relevant in long baseline searches.
Effect of timing noise on targeted and narrow-band coherent searches for continuous gravitational waves from pulsars
NASA Astrophysics Data System (ADS)
Ashton, G.; Jones, D. I.; Prix, R.
Most searches for continuous gravitational waves from pulsars use Taylor expansions in the phase to model the spin-down of neutron stars. Studies of pulsars demonstrate that their electromagnetic (EM) emissions suffer from timing noise, small deviations in the phase from Taylor expansion models. How the mechanism producing EM emission is related to any continuous gravitational-wave (CW) emission is unknown; if they either interact or are locked in phase, then the CW will also experience timing noise. Any disparity between the signal and the search template used in matched filtering methods will result in a loss of signal-to-noise ratio, referred to as "mismatch." In this work we assume the CW suffers a level of timing noise similar to its EM counterpart. We inject and recover fake CW signals, which include timing noise generated from observational data on the Crab pulsar. Measuring the mismatch over durations of order ś10 months, the effect is, for the most part, found to be small. This suggests recent so-called "narrow-band" searches which placed upper limits on the signals from the Crab and Vela pulsars will not be significantly affected. At a fixed observation time, we find the mismatch depends upon the observation epoch. Considering the averaged mismatch as a function of observation time, we find that it increases as a power law with time, and so may become relevant in long baseline searches.
Narrow-band double-pass superluminescent diodes emitting at 1060 nm
Lobintsov, A A; Perevozchikov, M V; Shramenko, M V [Superlum Diodes Ltd., Moscow (Russian Federation); Yakubovich, S D [Moscow State Institute of Radio-Engineering, Electronics and Automation (Technical University), Moscow (Russian Federation)
Experimental data are presented which show that double-pass superluminescent diodes (SLDs) with fibre Bragg grating (FBG) based spectrally selective external reflectors offer emission linewidths in the range 0.1-1.0 nm, i.e., one to two orders of magnitude narrower in comparison with conventional SLDs and considerably broader in comparison with single-frequency semiconductor lasers. Their optical power at the single-mode fibre output reaches 5.0-8.0 mW, and can be raised to 50 mW using a semiconductor optical amplifier. (lasers)
Identification and extraction of photometric redshifts of quasars with narrow-band filters
NASA Astrophysics Data System (ADS)
Queiroz, C.; Raul Abramo, L.
Although quasars are valuable targets for many cosmological applications, imaging surveys employing optical broad-band filter systems are unable to obtain accurate photometric redshifts for these objects. Broad-band imaging surveys also have some difficulty in distinguishing quasars from stars and HII regions of galaxies. However, the construction of a high-purity catalog of quasars, with accurate photometric redshifts, can be much more efficient with medium or narrow-band surveys, such as the upcoming J-PAS. In this work we discuss how to overcome the degeneracies in the color-color and color-magnitude diagrams that hamper the efficient detection of quasars, and how to obtain very good (near spectroscopic) photometric redshifts for these objects. In particular, we discuss how to include quasars in some of the most popular redshift codes, and the parallel need for the inclusion of spectral libraries for stars. We also discuss the importance of a good modeling of the distribution of point-sources in the sky, and the need for reliable luminosity functions that can inform the Bayesian estimation of types and photometric redshifts.
Band gap narrowing in zinc oxide-based semiconductor thin films
Kumar, Jitendra, E-mail: email@example.com, E-mail: firstname.lastname@example.com; Kumar Srivastava, Amit, E-mail: email@example.com, E-mail: email@example.com [Materials Science Programme, Indian Institute of Technology Kanpur, Kanpur 208016 (India)
A simple expression is proposed for the band gap narrowing (or shrinkage) in semiconductors using optical absorption measurements of spin coated 1 at.?% Ga-doped ZnO (with additional 0¢1.5 at.?% zinc species) thin films as ?E{sub BGN}?=?Bn{sup 1/3} [1 ? (n{sub c}/n){sup 1/3}], where B is the fitting parameter, n is carrier concentration, and n{sub c} is the critical density required for shrinkage onset. Its uniqueness lies in not only describing variation of ?E{sub BGN} correctly but also allowing deduction of n{sub c} automatically for several M-doped ZnO (M: Ga, Al, In, B, Mo) systems. The physical significance of the term [1 ? (n{sub c}/n){sup 1/3}] is discussed in terms of carrier separation.
Mechanism of phase conjugation via stimulated Brillouin scattering in narrow band gap semiconductors
NASA Astrophysics Data System (ADS)
Singh, M.; Aghamkar, P.
We develop a theoretical model to study optical phase conjugation via stimulated Brillouin scattering (OPC-SBS) in narrow band gap transversely magnetized semiconductors. Threshold value of pump electric field and reflectivity of the image radiation for the onset of OPC-SBS are estimated. The analysis is applied to both cases viz. centrosymmetric (CS) and non-centrosymmetric (NCS) crystals. Numerical estimates made for n-type InSb crystal at liquid nitrogen temperature duly irradiated by nanosecond pulsed 10.6 ?m CO 2 laser shows that high OPC-SBS reflectivity (90%) can be achieved in NCS crystals at moderate pump electric fields if the crystal is used as an optical waveguide with relatively large interaction length ( L = 5 mm) which proves its potential in practical applications such as fabrication of phase conjugate mirrors.
Narrow-band spectroscopic source of coherent radiation, tunable in the mid-IR range
Marquez, J; Voelkel, D; Huisken, F [Max-Plank Institut fur Stromungsforschung, Gottingen (Germany); Orlov, Sergei N; Polivanov, Yurii N; Smirnov, Valery V; Chuzavkov, Yu L [A.M. Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)
A description is given of a repetitively pulse source of narrow-band coherent radiation with continuous frequency tuning in the ranges 1.5-1.85 {mu}m and 2.5-3.7 {mu}m, and with energies per pulse up to 8 and 3 mJ, respectively. The source is based on parametric amplification of a weak IR signal from a difference-frequency generator or from a single-mode optical parametric oscillator. This source was used to determine the spectra of IR absorption and of degenerate four-wave mixing, as well as the spectra of excitation of stimulated resonance Raman scattering of light in some molecules under static or supersonic jet conditions. (nonlinear optical phenomena and devices)
Catalyzed Water Oxidation by Solar Irradiation of Band-Gap-Narrowed Semiconductors (Part 1. Overview).
Fujita,E.; Khalifah, P.; Lymar, S.; Muckerman, J.T.; Rodgriguez, J.
The objectives of this report are: (1) Investigate the catalysis of water oxidation by cobalt and manganese hydrous oxides immobilized on titania or silica nanoparticles, and dinuclear metal complexes with quinonoid ligands in order to develop a better understanding of the critical water oxidation chemistry, and rationally search for improved catalysts. (2) Optimize the light-harvesting and charge-separation abilities of stable semiconductors including both a focused effort to improve the best existing materials by investigating their structural and electronic properties using a full suite of characterization tools, and a parallel effort to discover and characterize new materials. (3) Combine these elements to examine the function of oxidation catalysts on Band-Gap-Narrowed Semiconductor (BGNSC) surfaces and elucidate the core scientific challenges to the efficient coupling of the materials functions.
In-band pumped polarized, narrow-linewidth Er:YAG laser at 1645 nm.
Wang, Mingjian; Meng, Junqing; Hou, Xia; Chen, Weibiao
We report a polarized, narrow-linewidth Er:YAG laser operating at 1645Ānm, in-band pumped by a continuous-wave (CW), narrowband 1532Ānm fiber-coupled laser diode (LD). A maximum polarized continuous wave output power of 8.45ĀW was obtained, resulting in an optical conversion efficiency of 56% with respect to the absorbed pump power. The central wavelength was measured to be 1645.45Ānm, with a full width at half-maximum of 0.13Ānm. For Q-switched operation, pulse energy of 12ĀmJ at 100ĀHz pulse repetition frequency and 95Āns pulse duration was yielded. To the best of our knowledge, this polarized pulse energy is the highest energy reported for a Q-switched Er:YAG laser pumped by a CW LD. PMID:25402806
Narrow band imaging with magnification for the diagnosis of lesions in the upper gastrointestinal tract
Singh, Rajvinder; Hussain, Asif; Loong, Cheong Kuan
Endoscopy plays an important role in the diagnosis and management of gastrointestinal (GI) tract disorders. Chromoendoscopy has proven to be superior to white light endoscopy for early detection of various GI lesions. This has however been fraught with problems. The use of color stains, time taken to achieve an effect and the learning curve associated with the technique has been some of the pitfalls. Narrow band imaging (NBI) particularly in combination with magnifying endoscopy may allow the endoscopist to accomplish a fairly accurate diagnosis with good histological correlation similar to results achieved with chromoendoscopy. Such enhanced detection of pre-malignant and early neoplastic lesions in the gastrointestinal tract should allow better targeting of biopsies and could ultimately prove to be cost effective. Various studies have been done demonstrating the utility of this novel technology. This article will review the impact of NBI in the diagnosis of upper gastrointestinal tract disorders. PMID:24368933
Catalyzed Water Oxidation by Solar Irradiation of Band-Gap-Narrowed Semiconductors (Part 2. Overview).
Fujita,E.; Khalifah, P.; Lymar, S.; Muckerman, J.T.; Rodriguez, J.
The objectives of this report are: (1) Investigate the catalysis of water oxidation by cobalt and manganese hydrous oxides immobilized on titania or silica nanoparticles, and dinuclear metal complexes with quinonoid ligands in order to develop a better understanding of the critical water oxidation chemistry, and rationally search for improved catalysts. (2) Optimize the light-harvesting and charge-separation abilities of stable semiconductors including both a focused effort to improve the best existing materials by investigating their structural and electronic properties using a full suite of characterization tools, and a parallel effort to discover and characterize new materials. (3) Combine these elements to examine the function of oxidation catalysts on Band-Gap-Narrowed Semiconductor (BGNSC) surfaces and elucidate the core scientific challenges to the efficient coupling of the materials functions.
The method of narrow-band audio classification based on universal noise background model
NASA Astrophysics Data System (ADS)
Rui, Rui; Bao, Chang-chun
Audio classification is the basis of content-based audio analysis and retrieval. The conventional classification methods mainly depend on feature extraction of audio clip, which certainly increase the time requirement for classification. An approach for classifying the narrow-band audio stream based on feature extraction of audio frame-level is presented in this paper. The audio signals are divided into speech, instrumental music, song with accompaniment and noise using the Gaussian mixture model (GMM). In order to satisfy the demand of actual environment changing, a universal noise background model (UNBM) for white noise, street noise, factory noise and car interior noise is built. In addition, three feature schemes are considered to optimize feature selection. The experimental results show that the proposed algorithm achieves a high accuracy for audio classification, especially under each noise background we used and keep the classification time less than one second.
New Design of Integrated 2D Photonic Crystal Narrow Band Filters Using the FDTD-2D Method
NASA Astrophysics Data System (ADS)
Badaoui, Hadjira Abri; Abri, Mehadji
In this paper, integrated 2D photonic crystal narrow band filter design is achieved based on transmission spectra shift. The presented effective technique for the design of narrow band resonant filters obtained by one-missing-row and by choosing proper radii of air holes of the waveguide is proposed. The 2D photonic crystals are designed by utilizing cascaded waveguides with different radii of air holes. The results are presented for normal incident wave with TE polarizations with a narrow spectral bandwidth centered at ? = 1.55 ?m. We also discuss the filtering process and its necessary modifications to achieve efficient filtering. A final synthesized filter topology is presented and a band from 1.53 ?m to 1.57 ?m around 1.55 ?m is transmitted with a maximum transmission of about 77% with better performances is achieved.
Rapid narrow band elution for on-line SPE using a novel solvent plug injection technique.
Gode, David; Martin, Markus M; Steiner, Frank; Huber, Christian G; Volmer, Dietrich A
Determination of trace constituents in biological and environmental samples usually requires a pre-concentration step. While solid-phase extraction (SPE) has been widely used, it is slow, labor intensive and adversely affected by analytical errors from handling. On-line SPE eliminates some of the flaws but often suffers from solvent compatibility problems with the subsequent chromatography separation. In this study, we are presenting a technical solution for overcoming some of these compatibility issues, by utilizing a fully automated, focused SPE sample transfer technique utilizing narrow-band solvent plugs, for seamless hyphenation with high-performance liquid chromatography (HPLC) or flow injection mass spectrometry (MS). A wide range of pharmaceutical compounds was studied in different sample matrices. Short plugs of high elution strength solvent were generated by means of an electrically actuated sample loop and enrichment and transfer steps monitored using on-line SPE-MS. The impact of the solvent plugs on chromatographic separation was studied using hyphenated SPE-LC-MS. By carefully examining elution profiles of solvent plugs of different compositions, optimum conditions for quantitative elution within well-defined volumes were found for all substances. In addition, the highly focused elution bands resulted in excellent retention time and peak area reproducibilities when injected on-line onto HPLC columns. Finally, to demonstrate proof-of-principle, the fully integrated on-line SPE-LC-MS system was applied to the analysis of spiked urine and river water samples. PMID:22669308
Band-gap narrowing in highly doped n- and p-type GaAs studied by photoluminescence spectroscopy
NASA Astrophysics Data System (ADS)
Borghs, G.; Bhattacharyya, K.; Deneffe, K.; Van Mieghem, P.; Mertens, R.
Band-gap narrowing of GaAs as a function of doping concentration has been measured using photoluminescence spectroscopy on samples grown by molecular beam epitaxy. Both n- (Si) and p- (Be) doped samples with concentrations varying from 3ū1017 to 3ū1018 cm-3 have been measured. The experimental results obtained from a line-shape analysis of the spectra taking tailing effects into account are in good agreement with recent theoretical calculations. A simple expression for the band-gap narrowing as a function of concentration for both n-and p-doped GaAs is given.
A blue optical filter for narrow-band imaging in endoscopic capsules
NASA Astrophysics Data System (ADS)
Silva, M. F.; Ghaderi, M.; Goncalves, L. M.; de Graaf, G.; Wolffenbuttel, R. F.; Correia, J. H.
This paper presents the design, simulation, fabrication, and characterization of a thin-film Fabry-Perot resonator composed of titanium dioxide (TiO2) and silicon dioxide (SiO2) thin-films. The optical filter is developed to be integrated with a light emitting diode (LED) for enabling narrow-band imaging (NBI) in endoscopy. The NBI is a high resolution imaging technique that uses spectrally centered blue light (415 nm) and green light (540 nm) to illuminate the target tissue. The light at 415 nm enhances the imaging of superficial veins due to their hemoglobin absorption, while the light at 540 nm penetrates deeper into the mucosa, thus enhances the sub-epithelial vessels imaging. Typically the endoscopes and endoscopic capsules use white light for acquiring images of the gastrointestinal (GI) tract. However, implementing the NBI technique in endoscopic capsules enhances their capabilities for the clinical applications. A commercially available blue LED with a maximum peak intensity at 404 nm and Full Width Half Maximum (FWHM) of 20 nm is integrated with a narrow band blue filter as the NBI light source. The thin film simulations show a maximum spectral transmittance of 36 %, that is centered at 415 nm with FWHM of 13 nm for combined the blue LED and a Fabry Perot resonator system. A custom made deposition scheme was developed for the fabrication of the blue optical filter by RF sputtering. RF powered reactive sputtering at 200 W with the gas flows of argon and oxygen that are controlled for a 5:1 ratio gives the optimum optical conditions for TiO2 thin films. For SiO2 thin films, a non-reactive RF sputtering at 150 W with argon gas flow at 15 sccm results in the best optical performance. The TiO2 and SiO2 thin films were fully characterized by an ellipsometer in the wavelength range between 250 nm to 1600 nm. Finally, the optical performance of the blue optical filter is measured and presented.
Narrow band quantitative and multivariate electroencephalogram analysis of peri-adolescent period
Background The peri-adolescent period is a crucial developmental moment of transition from childhood to emergent adulthood. The present report analyses the differences in Power Spectrum (PS) of the Electroencephalogram (EEG) between late childhood (24 children between 8 and 13 years old) and young adulthood (24 young adults between 18 and 23 years old). Results The narrow band analysis of the Electroencephalogram was computed in the frequency range of 0¢20 Hz. The analysis of mean and variance suggested that six frequency ranges presented a different rate of maturation at these ages, namely: low delta, delta-theta, low alpha, high alpha, low beta and high beta. For most of these bands the maturation seems to occur later in anterior sites than posterior sites. Correlational analysis showed a lower pattern of correlation between different frequencies in children than in young adults, suggesting a certain asynchrony in the maturation of different rhythms. The topographical analysis revealed similar topographies of the different rhythms in children and young adults. Principal Component Analysis (PCA) demonstrated the same internal structure for the Electroencephalogram of both age groups. Principal Component Analysis allowed to separate four subcomponents in the alpha range. All these subcomponents peaked at a lower frequency in children than in young adults. Conclusions The present approaches complement and solve some of the incertitudes when the classical brain broad rhythm analysis is applied. Children have a higher absolute power than young adults for frequency ranges between 0-20 Hz, the correlation of Power Spectrum (PS) with age and the variance age comparison showed that there are six ranges of frequencies that can distinguish the level of EEG maturation in children and adults. The establishment of maturational order of different frequencies and its possible maturational interdependence would require a complete series including all the different ages. PMID:22920159
Gas Distributions in Comet ISONÆs Coma: Concurrent Integral-Field Spectroscopy and Narrow-band Imaging.
NASA Astrophysics Data System (ADS)
Schmidt, Carl; Johnson, Robert E.; Baumgardner, Jeffrey; Mendillo, Michael
At a solar distance of 0.44 AU, Oort cloud comet C/2012 S1 (ISON) exhibited an outburst phase that was observed by small telescopes at the McDonald Observatory. In conjunction with narrow-band (14┼) imaging over a wide-field, an image-slicer spectrograph ( 20,000) simultaneously measured the spatial distribution of ISONÆs coma over a 1.6 x 2.7 arcminute field made up of 246 individual spectra. More than fifty emission lines from C2, NH2, CO, H2O+ and Na were observed within a single Echelle order spanning 5868┼ to 5930┼. Spatial reconstructions of these species reveal that ISONÆs coma was quite elongated several thousand km along the axis perpendicular to its motion. The ion tail appeared distinctly broader than the neutral Na tail, providing strong evidence that Na in the coma did not originate by dissociative recombination of a sodium bearing molecular ion. Production rates increased from 1.6 ▒ 0.3 x 1023 to 5.8 ▒ 1 x 1023 Na atoms/s within 24 hours, outgassing much less than comparable comets relative to ISONÆs water production. The anti-sunward Na tail was imaged >106 km from the nucleus. Its distribution indicates origins both near the nucleus and in the dust tail, with the ratio of these Na sources varying on hourly timescales due to outburst activity.
Light-Emitting Diode-Assisted Narrow Band Imaging Video Endoscopy System in Head and Neck Cancer
Chang, Hsin-Jen; Wang, Wen-Hung; Chang, Yen-Liang; Jeng, Tzuan-Ren; Wu, Chun-Te; Angot, Ludovic; Lee, Chun-Hsing
Background/Aims To validate the effectiveness of a newly developed light-emitting diode (LED)-narrow band imaging (NBI) system for detecting early malignant tumors in the oral cavity. Methods Six men (mean age, 51.5 years) with early oral mucosa lesions were screened using both the conventional white light and LED-NBI systems. Results Small elevated or ulcerative lesions were found under the white light view, and typical scattered brown spots were identified after shifting to the LED-NBI view for all six patients. Histopathological examination confirmed squamous cell carcinoma. The clinical stage was early malignant lesions (T1), and the patients underwent wide excision for primary cancer. This is the pilot study documenting the utility of a new LED-NBI system as an adjunctive technique to detect early oral cancer using the diagnostic criterion of the presence of typical scattered brown spots in six high-risk patients. Conclusions Although large-scale screening programs should be established to further verify the accuracy of this technology, its lower power consumption, lower heat emission, and higher luminous efficiency appear promising for future clinical applications.
Line by line and statistical narrow-band calculations of radiative transfer in some atmospheric entry problems
NASA Astrophysics Data System (ADS)
RiviĶre, Philippe; Soufiani, Anouar; Perrin, Marie-Yvonne
The aim of this paper is to contribute to the benchmarking of radiative properties and radiative transfer in high temperature gases through test cases 1 and 3. A line by line (LBL) approach, based on exhaustive spectroscopic data that were previously developed in our laboratory, is used for both cases. For test case 1, a good global agreement is found between our calculations and the emission spectra measured by Laux (1993) from an ICP air plasma torch, producing LTE air plasma at temperatures up to 7600K. Detailed comparisons show however some differences in the background level and, sometimes, in the absolute intensity and spectral position of the emitted signal. Most of these discrepancies are attributed to experimental calibrations that were corrected in more recent experiments (Laux 2002). Our contribution for test case 3 consists in computing radiative transfer in the wake of an axially symmetric body entering Martian atmosphere. Temperature and concentration fields are prescribed entries. We use line by line calculations with a ray-tracing method to provide reference solutions and develop a statistical narrow-band (SNB) model suitable for high temperature-low pressure applications. The analysis of radiative transfer in this application shows that the medium cannot be considered as optically thin and that the application of the weak absorption limit of SNB models, or equivalently, a smeared rotational model, leads to important discrepancies. The accuracy and numerical efficiency of the SNB model are emphasised.
Absorption of Narrow-Gap HgCdTe Near the Band Edge Including Nonparabolicity and the Urbach Tail
Flatte, Michael E.
Absorption of Narrow-Gap HgCdTe Near the Band Edge Including Nonparabolicity and the Urbach Tail, USA. 6.--e-mail: email@example.com An analytical model describing the absorption behavior of Hg1-x. This model smoothly fits experimental absorption coefficients over energies ranging from the Urbach tail
Narrow-band search of continuous gravitational-wave signals from Crab and Vela pulsars in Virgo VSR4 data
Aasi, J.
In this paper we present the results of a coherent narrow-band search for continuous gravitational-wave signals from the Crab and Vela pulsars conducted on Virgo VSR4 data. In order to take into account a possible small ...
Magnifying endoscopy with narrow band imaging for predicting the invasion depth of superficial esophageal squamous cell carcinoma.
Goda, K; Tajiri, H; Ikegami, M; Yoshida, Y; Yoshimura, N; Kato, M; Sumiyama, K; Imazu, H; Matsuda, K; Kaise, M; Kato, T; Omar, S
The invasion depth of superficial esophageal squamous cell carcinoma is important in determining therapeutic strategy. The aim of this study was to prospectively investigate the clinical utility of magnifying endoscopy with narrow band imaging compared with that of non-magnifying high-resolution endoscopy or high-frequency endoscopic ultrasonography in predicting the depth of superficial esophageal squamous cell carcinoma. The techniques were carried out in 72 patients with 101 superficial esophageal squamous cell carcinomas, which were then resected by either endoscopic mucosal resection or esophagectomy. The histological invasion depth was divided into two: mucosal or submucosal carcinoma. We investigated the relationship between endoscopic staging and histology of tumor depth. Non-magnifying high-resolution endoscopy, magnifying endoscopy with narrow band imaging, and high-frequency endoscopic ultrasonography had overestimation/underestimation rates of 7/5, 4/4 and 8/3%, respectively. The sensitivity rates for the three techniques were 72, 78, and 83%, respectively, and the specificity rates were 92, 95, and 89%, respectively. There were no statistically significant differences among the three endoscopic techniques. Clinical utility of magnifying endoscopy with narrow band imaging does not seem to be significantly different from that of non-magnifying high-resolution endoscopy or high-frequency endoscopic ultrasonography in predicting the depth of superficial esophageal squamous cell carcinoma. Magnifying endoscopy with narrow band imaging may have potential to reduce overestimation risks of non-magnifying high-resolution endoscopy or high-frequency endoscopic ultrasonography. PMID:19222533
Multicolor Fluorescent Semiconducting Polymer Dots with Narrow Emissions and High Brightness
Rong, Yu; Wu, Changfeng; Yu, Jiangbo; Zhang, Xuanjun; Ye, Fangmao; Zeigler, Maxwell; Gallina, Maria Elena; Wu, I-Che; Zhang, Yong; Chan, Yang-Hsiang; Sun, Wei; Uvdal, Kajsa; Chiu, Daniel T.
Fluorescent semiconducting polymer dots (Pdots) have attracted great interest because of their superior characteristics as fluorescent probes, such as high fluorescence brightness, fast radiative rates, and excellent photostability. However, currently available Pdots generally exhibit broad emission spectra, which significantly limit their usefulness in many biological applications involving multiplex detections. Here, we describe the design and development of multicolor narrow emissive Pdots based on different boron-dipyrromethene (BODIPY) units. BODIPY-containing semiconducting polymers emitting at multiple wavelengths were synthesized and used as precursors for preparing the Pdots, where intra-particle energy transfer led to highly bright, narrow emissions. The emission full-width at half maximum (FWHM) of the resulting Pdots varies from 40 nm to 55 nm, which is 1.5~2 times narrower than those of conventional semiconducting polymer dots. BODIPY520 Pdots was about an order of magnitude brighter than commercial Qdot 525 under identical laser excitation conditions. Fluorescence imaging and flow cytometry experiments indicate the narrow emissions from these bright Pdots are promising for multiplexed biological detections. PMID:23282278
Multicolor fluorescent semiconducting polymer dots with narrow emissions and high brightness.
Rong, Yu; Wu, Changfeng; Yu, Jiangbo; Zhang, Xuanjun; Ye, Fangmao; Zeigler, Maxwell; Gallina, Maria Elena; Wu, I-Che; Zhang, Yong; Chan, Yang-Hsiang; Sun, Wei; Uvdal, Kajsa; Chiu, Daniel T
Fluorescent semiconducting polymer dots (Pdots) have attracted great interest because of their superior characteristics as fluorescent probes, such as high fluorescence brightness, fast radiative rates, and excellent photostability. However, currently available Pdots generally exhibit broad emission spectra, which significantly limit their usefulness in many biological applications involving multiplex detections. Here, we describe the design and development of multicolor narrow emissive Pdots based on different boron dipyrromethene (BODIPY) units. BODIPY-containing semiconducting polymers emitting at multiple wavelengths were synthesized and used as precursors for preparing the Pdots, where intraparticle energy transfer led to highly bright, narrow emissions. The emission full width at half-maximum of the resulting Pdots varies from 40 to 55 nm, which is 1.5-2 times narrower than those of conventional semiconducting polymer dots. BODIPY 520 Pdots were about an order of magnitude brighter than commercial Qdot 525 under identical laser excitation conditions. Fluorescence imaging and flow cytometry experiments indicate that the narrow emissions from these bright Pdots are promising for multiplexed biological detections. PMID:23282278
Effects of Narrow Band UVB (311 nm) Irradiation on Epidermal Cells
Reich, Adam; M?drek, Karolina
Ultraviolet radiation (UVR) is known to be one of the most important environmental hazards acting on the skin. It was revealed that chronic exposure to UVR accelerates skin aging, induces immunosuppression and may lead to the development of skin cancers. On the other hand, UVR has been shown to be effective in the treatment of numerous skin diseases and thus, various phototherapy modalities have been developed to date. Narrow-band ultraviolet B (NB-UVB) emitting a light with a peak around 311 nm has been demonstrated to be effective in the treatment of various skin disorders; currently it is one of the most commonly used phototherapy devices. Despite NB-UVB has been developed more than 30 years ago, the exact mechanism of its therapeutic action remains poorly understood. To date, most of NB-UVB effects were attributed to its influence on immune cells; however, nearly 90% of NB-UVB irradiation is absorbed by epidermis and keratinocytes seem to be important players in mediating NB-UVB biological activity. Here, we have reviewed the current data about the influence of NB-UVB on epidermal cells, with a special emphasis on cell proliferation and death. PMID:23594996
Barrett's esophageal adenocarcinoma diagnosed by narrow-band imaging magnifying endoscopy.
Takahashi, Akiko; Oyama, Tsuneo
A 40-year-old man was referred to our hospital for detailed examination of a protuberant lesion in long-segment Barrett's esophagus (LSBE). Under white light endoscopy (WLE) the lesion appeared as a protuberant lesion with a rough surface and was diagnosed as 0-IIa-type tumor suspected to be a well-differentiated adenocarcinoma. A regular villous pattern was shown in the background mucosa of the LSBE by narrow-band imaging (NBI) magnifying endoscopy (NBI-ME). However, a slightly irregular villous pattern was observed on the lateral side of the main lesion. Therefore, a 0-IIa-type tumor was estimated to have a flatly lateral extension component (i.e. 0-IIb spreading). The 0-IIb spreading was unclear when using WLE, but could be diagnosed by NBI-ME based on the surface pattern differences. Markings were placed outside the edge of the flatly lateral extension, and endoscopic submucosal dissection was carried out.The pathological diagnosis of the protuberant lesion with flatly lateral spreading was well-differentiated adenocarcinoma. The macroscopic type was 0-IIa+IIb, 45 ū 43 mm in size. The invasion depth was T1a (deep muscularis mucosae). Lymphatic and venous invasions were negative; horizontal and vertical margins were negative. In conclusion, NBI-ME was useful for the diagnosis of the flatly lateral extension of this 0-IIa+IIb esophageal adenocarcinoma in Barrett's esophagus. Further investigations with many cases are necessary. PMID:23617675
Narrow-band imaging with magnifying endoscopy for the evaluation of gastrointestinal lesions
Boeriu, Alina; Boeriu, Cristian; Drasovean, Silvia; Pascarenco, Ofelia; Mocan, Simona; Stoian, Mircea; Dobru, Daniela
Narrow band imaging (NBI) endoscopy is an optical image enhancing technology that allows a detailed inspection of vascular and mucosal patterns, providing the ability to predict histology during real-time endoscopy. By combining NBI with magnification endoscopy (NBI-ME), the accurate assessment of lesions in the gastrointestinal tract can be achieved, as well as the early detection of neoplasia by emphasizing neovascularization. Promising results of the method in the diagnosis of premalignant and malignant lesions of gastrointestinal tract have been reported in clinical studies. The usefulness of NBI-ME as an adjunct to endoscopic therapy in clinical practice, the potential to improve diagnostic accuracy, surveillance strategies and cost-saving strategies based on this method are summarized in this review. Various classification systems of mucosal and vascular patterns used to differentiate preneoplastic and neoplastic lesions have been reviewed. We concluded that the clinical applicability of NBI-ME has increased, but standardization of endoscopic criteria and classification systems, validation in randomized multicenter trials and training programs to improve the diagnostic performance are all needed before the widespread acceptance of the method in routine practice. However, published data regarding the usefulness of NBI endoscopy are relevant in order to recommend the method as a reliable tool in diagnostic and therapy, even for less experienced endoscopists. PMID:25685267
Visualization of mucosal vasculature with narrow band imaging: a theoretical study
NASA Astrophysics Data System (ADS)
Wang, Quanzeng; Le, Du; Ramella-Roman, Jessica; Pfefer, Joshua
Narrow band imaging (NBI) is a spectrally-selective reflectance imaging technique that is used as an adjunctive approach to endoscopic detection of mucosal abnormalities such as neoplastic lesions. While numerous clinical studies in tissue sites such as the esophagus, oral cavity and lung indicate the efficacy of this approach, it is not well theoretically understood. In this study, we performed Monte Carlo simulations to elucidate the factors that affect NBI device performance. The model geometry involved a two-layer turbid medium based on mucosal tissue optical properties and embedded cylindrical, blood-filled vessels at varying diameters and depths. Specifically, we studied the effect of bandpass filters (415+/-15 nm, 540+/-10 nm versus white light), blood vessel diameter (20-400 ?m) and depth (30 - 450 ?m), wavelength, and bandwidth on vessel contrast. Our results provide a quantitative evaluation of the two mechanisms that are commonly believed to be the primary components of NBI: (i) the increased contrast provided by high hemoglobin absorption and (ii) increase in the penetration depth produced by the decrease in scattering with increasing wavelength. Our MC model can provide novel, quantitative insight into NBI, may lead to improvements in its performance.
Narrow band pulses as stimuli in an auditory brain stem recording study with a harbor porpoise
NASA Astrophysics Data System (ADS)
Beedholm, Kristian; Miller, Lee A.
We have studied several aspects of hearing by a harbor porpoise using the ABR method with pulsed stimuli. Experiments were conducted on a male porpoise in collaboration with Fjord and Baelt, Kerteminde, Denmark. The animal had suction cups containing silver electrodes placed near the blowhole and near the dorsal fin. When fitted with the electrodes he moved to an underwater listening post where his outgoing sonar signal could be used to trigger a phantom echo. EEG signals were amplified differentially and averaged over a variable number of presentations depending on trial duration and experiment. For studying the frequency/intensity response, narrow band pulsed stimuli were generated and presented in several ways. One way was to use the impulse response of a B&K 1/3 octave filter bank (set to 80, 100, 125, or 160 kHz) as a stimulus. This stimulus was presented in both a passive hearing task, when a signal generator triggered the echo, and in an active experiment, where the echo was time locked to the animals emitted signal. Our results show the best response at 125 kHz and indicate a slight, but significantly higher response in the active mode. The latter has a methodological explanation. [Work supported by ONR.
"Leopard skin sign": the use of narrow-band imaging with magnification endoscopy in celiac disease.
Tchekmedyian, Asadur J; Coronel, Emmanuel; Czul, Frank
Celiac Disease (CD) is an immune reaction to gluten containing foods such as rye, wheat and barley. This condition affects individuals with a genetic predisposition; it targets the small bowel and may cause symptoms including diarrhea, malabsorption, weight loss, abdominal pain and bloating. The diagnosis is made by serologic testing of celiac-specific antibodies and confirmed by histology. Certain endoscopic characteristics, such as scalloping, reduction in the number of folds, mosaic-pattern mucosa or nodular mucosa, are suggestive of CD and can be visualized under white light endoscopy. Due to its low sensitivity, endoscopy alone is not recommended to diagnose CD; however, enhanced visual identification of suspected mucosal abnormalities through the use of new technologies, such as narrow band imaging with magnification (NBI-ME), could assist in targeting biopsies and thereby increasing the sensitivity of endoscopy. This is a case series of seven patients with serologic and histologic diagnoses of CD who underwent upper endoscopies with NBI-ME imaging technology as part of their CD evaluation. By employing this imaging technology, we could identify patchy atrophy sites in a mosaic pattern, with flattened villi and alteration of the central capillaries of the duodenal mucosa. We refer to this epithelial pattern as "Leopard Skin Sign". Since epithelial lesions are easily seen using NBI-ME, we found it beneficial for identifying and targeting biopsy sites. Larger prospective studies are warranted to confirm our findings. PMID:25594756
Narrow-band ultraviolet B phototherapy in patients with recalcitrant nodular prurigo.
Tamagawa-Mineoka, Risa; Katoh, Norito; Ueda, Eiichiro; Kishimoto, Saburo
Management of nodular prurigo has been less than satisfactory. Conventional therapies such as systemic antihistamines and topical steroids have not been particularly successful. The effects of narrow-band ultraviolet B (NB-UVB) phototherapy in the treatment of various inflammatory dermatoses have been proven, however, no data exist on the efficacy and the duration of remission in NB-UVB monotherapy for nodular prurigo. The aim of this study was to evaluate the effect of NB-UVB phototherapy on recalcitrant nodular prurigo. NB-UVB phototherapy was performed once a week on 10 patients with recalcitrant nodular prurigo. The initial dose was 0.4 J/cm(2), and the dose was increased by 0.1 J/cm(2) for each treatment. The treatment was performed until the eruption was almost clear. In each patient, a mean cumulative dose of 23.88 J/cm(2) was applied over a mean of 24.3 irradiations. The mean maximum daily dose of ultraviolet B was 1.2 +/- 0.4 J/cm(2). NB-UVB phototherapy notably improved the eruption of nodular prurigo in all patients. Follow up at 1 year revealed that only one patient had relapsed. The remaining nine patients continued to derive long-term benefits. NB-UVB phototherapy appears to be an effective treatment for recalcitrant nodular prurigo, offering long-term benefits in the majority of those treated. PMID:17908139
A fast switch, combiner and narrow-band filter for high-power millimetre wave beams
NASA Astrophysics Data System (ADS)
Kasparek, W.; Petelin, M. I.; Shchegolkov, D. Yu; Erckmann, V.; Plaum, B.; Bruschi, A.; ECRH Groups at IPP Greifswald; Karlsruhe, FZK; Stuttgart, IPF
A fast directional switch (FADIS) is described, which allows controlled switching of high-power microwaves between two outputs. A possible application could be synchronous stabilization of neoclassical tearing modes (NTMs). Generally, the device can be used to share the installed EC power between different types of launchers or different applications (e.g. in ITER, midplane/upper launcher). The switching is performed electronically without moving parts by a small frequency-shift keying of the gyrotron (some tens of megahertz), and a narrow-band diplexer. The device can be operated as a beam combiner also, which offers attractive transmission perspectives in multi-megawatt ECRH systems. In addition, these diplexers are useful for plasma diagnostic systems employing high-power sources due to their filter characteristics. The principle and the design of a four-port quasi-optical resonator diplexer is presented. Low-power measurements of switching contrast, mode purity and efficiency show good agreement with theory. Preliminary frequency modulation characteristics of gyrotrons are shown, and first results from high-power switching experiments using the ECRH system for W7-X are presented.
1.064-?m laser damage studies of silicon oxy-nitride narrow band reflectors
NASA Astrophysics Data System (ADS)
Milward, Jonathan R.; Lewis, Keith L.; Sheach, K.; Heinecke, Rudolf A.
In a paper presented at the 1992 Boulder Damage Symposium, we discussed the role of electric field effects, defect type, surface roughness, film thickness and coating absorption on the laser damage thresholds of sinusoidally modulated, plasma deposited, silicon oxy-nitride narrow band reflectors. We concluded that the damage threshold, which was essentially constant at 2 J/cm2 at the test wavelength of 0.532 micrometers , was defect dominated. A sizeable fraction of the damage events occurred at a particular type of defect--a hemispherical hillock feature typically 5 micrometers in diameter as identified by SEM and interferometric surface profiling. We postulated that this defect initiated damage because of either a microlensing effect or an enhanced electric field effect. We have since measured the laser damage thresholds of all these samples at 1.064 micrometers , and found significant variations in the damage thresholds, which were a factor of three higher on average than those at 0.532 micrometers . The microlens model presented can explain damage thresholds up to a factor of four higher at the longer wavelength, and predicts a minimum nodule height for increased damage susceptibility. The minimum nodule height is dependent on the wavelength and the coating average index. The wavelength scaling of the fluence enhancement and the minimum nodule height imply that nodule initiated damage will become an even more serious problem as the wavelength approaches the UV.
Diagnosis of early gastric cancer using narrow band imaging and acetic acid
Matsuo, Ken; Takedatsu, Hidetoshi; Mukasa, Michita; Sumie, Hiroaki; Yoshida, Hikaru; Watanabe, Yasutomo; Akiba, Jun; Nakahara, Keita; Tsuruta, Osamu; Torimura, Takuji
AIM: To determine whether the endoscopic findings of depressed-type early gastric cancers (EGCs) could precisely predict the histological type. METHODS: Ninety depressed-type EGCs in 72 patients were macroscopically and histologically identified. We evaluated the microvascular (MV) and mucosal surface (MS) patterns of depressed-type EGCs using magnifying endoscopy (ME) with narrow-band imaging (NBI) (NBI-ME) and ME enhanced by 1.5% acetic acid, respectively. First, depressed-type EGCs were classified according to MV pattern by NBI-ME. Subsequently, EGCs unclassified by MV pattern were classified according to MS pattern by enhanced ME (EME) images obtained from the same angle. RESULTS: We classified the depressed-type EGCs into the following 2 MV patterns using NBI-ME: a fine-network pattern that indicated differentiated adenocarcinoma (25/25, 100%) and a corkscrew pattern that likely indicated undifferentiated adenocarcinoma (18/23, 78.3%). However, 42 of the 90 (46.7%) lesions could not be classified into MV patterns by NBI-ME. These unclassified lesions were then evaluated for MS patterns using EME, which classified 33 (81.0%) lesions as MS patterns, diagnosed as differentiated adenocarcinoma. As a result, 76 of the 90 (84.4%) lesions were matched with histological diagnoses using a combination of NBI-ME and EME. CONCLUSION: A combination of NBI-ME and EME was useful in predicting the histological type of depressed-type EGC. PMID:25632201
Quantitative evaluation of mucosal vascular contrast in narrow band imaging using Monte Carlo modeling
NASA Astrophysics Data System (ADS)
Le, Du; Wang, Quanzeng; Ramella-Roman, Jessica; Pfefer, Joshua
Narrow-band imaging (NBI) is a spectrally-selective reflectance imaging technique for enhanced visualization of superficial vasculature. Prior clinical studies have indicated NBI's potential for detection of vasculature abnormalities associated with gastrointestinal mucosal neoplasia. While the basic mechanisms behind the increased vessel contrast - hemoglobin absorption and tissue scattering - are known, a quantitative understanding of the effect of tissue and device parameters has not been achieved. In this investigation, we developed and implemented a numerical model of light propagation that simulates NBI reflectance distributions. This was accomplished by incorporating mucosal tissue layers and vessel-like structures in a voxel-based Monte Carlo algorithm. Epithelial and mucosal layers as well as blood vessels were defined using wavelength-specific optical properties. The model was implemented to calculate reflectance distributions and vessel contrast values as a function of vessel depth (0.05 to 0.50 mm) and diameter (0.01 to 0.10 mm). These relationships were determined for NBI wavelengths of 410 nm and 540 nm, as well as broadband illumination common to standard endoscopic imaging. The effects of illumination bandwidth on vessel contrast were also simulated. Our results provide a quantitative analysis of the effect of absorption and scattering on vessel contrast. Additional insights and potential approaches for improving NBI system contrast are discussed.
Narrow-band imaging with magnifying endoscopy for the evaluation of gastrointestinal lesions.
Boeriu, Alina; Boeriu, Cristian; Drasovean, Silvia; Pascarenco, Ofelia; Mocan, Simona; Stoian, Mircea; Dobru, Daniela
Narrow band imaging (NBI) endoscopy is an optical image enhancing technology that allows a detailed inspection of vascular and mucosal patterns, providing the ability to predict histology during real-time endoscopy. By combining NBI with magnification endoscopy (NBI-ME), the accurate assessment of lesions in the gastrointestinal tract can be achieved, as well as the early detection of neoplasia by emphasizing neovascularization. Promising results of the method in the diagnosis of premalignant and malignant lesions of gastrointestinal tract have been reported in clinical studies. The usefulness of NBI-ME as an adjunct to endoscopic therapy in clinical practice, the potential to improve diagnostic accuracy, surveillance strategies and cost-saving strategies based on this method are summarized in this review. Various classification systems of mucosal and vascular patterns used to differentiate preneoplastic and neoplastic lesions have been reviewed. We concluded that the clinical applicability of NBI-ME has increased, but standardization of endoscopic criteria and classification systems, validation in randomized multicenter trials and training programs to improve the diagnostic performance are all needed before the widespread acceptance of the method in routine practice. However, published data regarding the usefulness of NBI endoscopy are relevant in order to recommend the method as a reliable tool in diagnostic and therapy, even for less experienced endoscopists. PMID:25685267
Radio jet emission from GeV-emitting narrow-line Seyfert 1 galaxies
NASA Astrophysics Data System (ADS)
Angelakis, E.; Fuhrmann, L.; Marchili, N.; Foschini, L.; Myserlis, I.; Karamanavis, V.; Komossa, S.; Blinov, D.; Krichbaum, T. P.; Sievers, A.; Ungerechts, H.; Zensus, J. A.
Context. With the current study we aim at understanding the properties of radio emission and the assumed jet from four radio-loud and ?-ray-loud narrow-line Seyfert 1 galaxies that have been detected by Fermi. These are Seyfert 1 galaxies with emission lines at the low end of the FWHM distribution. Aims: The ultimate goal is twofold: first we investigate whether a relativistic jet is operating at the source producing the radio output, and second, we quantify the jet characteristics to understand possible similarities with and differences from the jets found in typical blazars. Methods: We relied on the most systematic monitoring of radio-loud and ?-ray-detected narrow-line Seyfert 1 galaxies in the cm and mm radio bands conducted with the Effelsberg 100 m and IRAM 30 m telescopes. It covers the longest time-baselines and the most radio frequencies to date. This dataset of multi-wavelength, long-term radio light-curves was analysed from several perspectives. We developed a novel algorithm to extract sensible variability parameters (mainly amplitudes and time scales) that were then used to compute variability brightness temperatures and the corresponding Doppler factors. The jet powers were computed from the light curves to estimate the energy output and compare it with that of typical blazars. The dynamics of radio spectral energy distributions were examined to understand the mechanism causing the variability. Results: The length of the available light curves for three of the four sources in the sample allowed a firm understanding of the general behaviour of the sources. They all display intensive variability that appears to be occurring at a pace rather faster than what is commonly seen in blazars. The flaring events become progressively more prominent as the frequency increases and show intensive spectral evolution that is indicative of shock evolution. The variability brightness temperatures and the associated Doppler factors are moderate, implying a mildly relativistic jet. The computed jet powers show very energetic flows. The radio polarisation in one case clearly implies a quiescent jet underlying recursive flaring activity. Finally, in one case, the sudden disappearance of a ?-ray flare below some critical frequency in our band needs a more detailed investigation of the possible mechanism causing the evolution of broadband events. Conclusions: Despite the generally lower flux densities, the sources appear to show all typical characteristics seen in blazars that are powered by relativistic jets, such as intensive variability, spectral evolution across the different bands following evolutionary paths explained by travelling shocks, and Doppler factors indicating mildly relativistic speeds. Appendices A and B are available in electronic form at http://www.aanda.orgData displayed in Figs. 2 and 3 (Table 7 is an example) are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://126.96.36.199) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/575/A55
Zhang, Kai; Wang, Ting-Gui; Dong, Xiao-Bo [Key Laboratory for Research in Galaxies and Cosmology, The University of Sciences and Technology of China, Chinese Academy of Sciences, Hefei, Anhui 230026 (China)] [Key Laboratory for Research in Galaxies and Cosmology, The University of Sciences and Technology of China, Chinese Academy of Sciences, Hefei, Anhui 230026 (China); Gaskell, C. Martin, E-mail: firstname.lastname@example.com, E-mail: email@example.com, E-mail: email@example.com, E-mail: email@example.com [Centro de Astrofisica de Valparaiso y Departamento de Fisica y Astronomia, Facultad de Ciencias, Universidad de Valparaiso, Av. Gran Bretana 1111, Valparaiso (Chile)
The anti-correlations between the equivalent widths of emission lines and the continuum luminosity in active galactic nuclei (AGNs), known as the Baldwin effect, are well established for broad lines, but are less well studied for narrow lines. In this paper we explore the Baldwin effect of narrow emission lines over a wide range of ionization levels and critical densities using a large sample of broad-line, radio-quiet AGNs taken from Sloan Digital Sky Survey Data Release 4. These type 1 AGNs span three orders of magnitude in continuum luminosity. We show that most narrow lines show a similar Baldwin effect slope of about -0.2, while the significant deviations of the slopes for [N II] {lambda}6583, [O II] {lambda}3727, [Ne V] {lambda}3425, and the narrow component of H{alpha} can be explained by the influence of metallicity, star formation contamination, and possibly by the difference in the shape of the UV-optical continuum. The slopes do not show any correlation with either the ionization potential or the critical density. We show that a combination of 50% variations in continuum near 5100 A and a lognormal distribution of observed luminosity can naturally reproduce a constant Baldwin effect slope of -0.2 for all narrow lines. The variations of the continuum could be due to variability, intrinsic anisotropic emission, or an inclination effect.
Photonic band-edge-induced enhancement in absorption and emission
NASA Astrophysics Data System (ADS)
Ummer, Karikkuzhi Variyath; Vijaya, Ramarao
An enhancement in photonic band-edge-induced absorption and emission from rhodamine-B dye doped polystyrene pseudo gap photonic crystals is studied. The band-edge-induced enhancement in absorption is achieved by selecting the incident angle of the excitation beam so that the absorption spectrum of the emitter overlaps the photonic band edge. The band-edge-induced enhancement in emission, on the other hand, is possible with and without an enhancement in band-edge-induced absorption, depending on the collection angle of emission. Through a simple set of measurements with suitably chosen angles for excitation and emission, we achieve a maximum enhancement of 70% in emission intensity with band-edge-induced effects over and above the intrinsic emission in the case of self-assembled opals. This is a comprehensive effort to interpret tunable lasing in opals as well as to predict the wavelength of lasing arising as a result of band-edge-induced distributed feedback effects.
Optical Structure and Colors of Faint Compact Narrow Emission-Line Galaxies
Rafael Guzman; Anna Jangren; David C. Koo; Matthew A. Bershady; Luc Simard
We present the results of Hubble Space Telescope Wide Field Planetary Camera imaging in V606 and I814 of five compact narrow emission line galaxies (CNELGs) and four slightly more extended faint blue galaxies (FBGs) with 20.3<=B<=22.4 and redshifts z~0.22 -0.66. Half-light radii are measured to span from 0.\\
Development of inexpensive optical broad- and narrow-band sensors for ecosystem research
NASA Astrophysics Data System (ADS)
Mollenhauer, Hannes; Cuntz, Thomas; Bumberger, Jan
The observation and monitoring of ecosystem processes are great challenges in environmental science, due to the dynamic and complexity of such procedures. To describe and understand biotic and abiotic processes and their interaction it is necessary to acquire multiple parameters, which are influencing the natural regime. Essential issues are: the detection of spatial heterogeneities and scale overlapping procedures in the environment. To overcome these problems an adequate monitoring system should cover a representative area as well as have a sufficient resolution in time and space. Hence, the needed quantity of sensors (depending on the observed parameters or processes) can be enormous. According to these issues, there is a high demand on low-cost sensor technologies (with adequate performances) to realize a delicate monitoring platform. In the case of vegetation processes, one key feature is to characterize photosynthetic activity of the plants in detail. Common investigation methods are based on optical measurements. Here photosynthetically active radiation (PAR) sensors and hyperspectral sensors are in major use. Photosynthetically active radiation (solar radiation from 400 to 700 nanometers) designates the spectral range that photosynthetic organisms are able to use in the process of photosynthesis. PAR sensors enable the detection of the reflected solar light of the vegetation in whole the PAR wave band. The amount of absorption indicates photosynthetic activity of the plant. Hyperspectral sensors observe specific parts of the solar light spectrum and facilitate the determination of the main pigment classes (Chlorophyll, Carotenoid and Anthocyanin). Due to absorption of pigments they producing a specific spectral signature in the visible part of the electromagnetic spectrum (narrow-band peaks). If vegetation is affected by water or nutritional deficience the proportion of light-absorbing pigments is reduced which finally results in an overall reduced light absorption. The resulting spectral signature then differs from usual reflectance patterns and can be used as stress indicator. Hence, reflectances between 550-700 nm are extremely sensitive regarding changing Chlorophyll contents. Both kinds of sensors based on semiconductor technologies whereby the material input can kept on low level. This work presents the development and testing of a practical, rugged, and inexpensive PAR and hyperspectral sensor. The sensors were made from a gallium arsenide phosphide (GaAsP) photodiodes and silicon photodiodes with different interference filters. First results of recorded long term in-situ data and linear regressions (in comparison to commercial products) show extremely high performances (coefficient of determination higher than 0.99) of the PAR sensors simultaneous to the cost cutting.
Non-proximity resonant tunneling in multi-core photonic band gap fibers: An efficient mechanism for engineering highly-selective ultra-narrow band pass splitters.
Florous, Nikolaos J; Saitoh, Kunimasa; Murao, Tadashi; Koshiba, Masanori; Skorobogatiy, Maksim
The objective of the present investigation is to demonstrate the possibility of designing compact ultra-narrow band-pass filters based on the phenomenon of non-proximity resonant tunneling in multi-core photonic band gap fibers (PBGFs). The proposed PBGF consists of three identical air-cores separated by two defected air-holes which act as highly-selective resonators. With a fine adjustment of the design parameters associated with the resonant-air-holes, phase matching at two distinct wavelengths can be achieved, thus enabling very narrow-band resonant directional coupling between the input and the two output cores. The validation of the proposed design is ensured with an accurate PBGF analysis based on finite element modal and beam propagation algorithms. Typical characteristics of the proposed device over a single polarization are: reasonable short coupling length of 2.7 mm, dual bandpass transmission response at wavelengths of 1.339 and 1.357 mum, with corresponding full width at half maximum bandwidths of 1.2 nm and 1.1 nm respectively, and a relatively high transmission of 95% at the exact resonance wavelengths. The proposed ultra-narrow band-pass filter can be employed in various applications such as all-fiber bandpass/bandstop filtering and resonant sensors. PMID:19516644
Non-proximity resonant tunneling in multi-core photonic band gap fibers: An efficient mechanism for engineering highly-selective ultra-narrow band pass splitters
NASA Astrophysics Data System (ADS)
Florous, Nikolaos J.; Saitoh, Kunimasa; Murao, Tadashi; Koshiba, Masanori; Skorobogatiy, Maksim
The objective of the present investigation is to demonstrate the possibility of designing compact ultra-narrow band-pass filters based on the phenomenon of non-proximity resonant tunneling in multi-core photonic band gap fibers (PBGFs). The proposed PBGF consists of three identical air-cores separated by two defected air-holes which act as highly-selective resonators. With a fine adjustment of the design parameters associated with the resonant-air-holes, phase matching at two distinct wavelengths can be achieved, thus enabling very narrow-band resonant directional coupling between the input and the two output cores. The validation of the proposed design is ensured with an accurate PBGF analysis based on finite element modal and beam propagation algorithms. Typical characteristics of the proposed device over a single polarization are: reasonable short coupling length of 2.7 mm, dual bandpass transmission response at wavelengths of 1.339 and 1.357 ?m, with corresponding full width at half maximum bandwidths of 1.2 nm and 1.1 nm respectively, and a relatively high transmission of 95% at the exact resonance wavelengths. The proposed ultra-narrow band-pass filter can be employed in various applications such as all-fiber bandpass/bandstop filtering and resonant sensors.
Endocytoscopic narrow-band imaging efficiency for evaluation of inflammatory activity in ulcerative colitis
Maeda, Yasuharu; Ohtsuka, Kazuo; Kudo, Shin-ei; Wakamura, Kunihiko; Mori, Yuichi; Ogata, Noriyuki; Wada, Yoshiki; Misawa, Masashi; Yamauchi, Akihiro; Hayashi, Seiko; Kudo, Toyoki; Hayashi, Takemasa; Miyachi, Hideyuki; Yamamura, Fuyuhiko; Ishida, Fumio; Inoue, Haruhiro; Hamatani, Shigeharu
AIM: To assess the efficacy of endocytoscopic narrow-band imaging (EC-NBI) for evaluating the severity of inflammation in ulcerative colitis (UC). METHODS: This retrospective study was conducted at a single tertiary care referral center. We included UC patients who underwent colonoscopy with endocytoscopy from July 2010 to December 2013. EC-NBI was performed, and the images were evaluated by assessing visibility, increased vascularization, and the increased calibers of capillaries and were classified as Obscure, Visible or Dilated. Obscure was indicative of inactive disease, while Visible and Dilated were indicative of acute inflammation. This study received Institutional Review Board approval. The primary outcome measures included the diagnostic ability of EC-NBI to distinguish between active and inactive UC on the basis of histological activity. The conventional endoscopic images were classified according to the Mayo endoscopic score. A score of 0 or 1 indicated inactive disease, whereas a score of 2 indicated active disease. RESULTS: Fifty-two patients were enrolled. There was a strong correlation between the EC-NBI findings and the histological assessment (r = 0.871, P < 0.01). The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of EC-NBI for diagnosing acute inflammation were 84.0%, 100%, 87.1%, 100%, and 92.3%, respectively, while those for the Mayo endoscopic score were 100%, 40.7%, 100%, 61.0%, and 69.2%, respectively. Compared with conventional endoscopy, EC-NBI was superior in diagnostic specificity, negative predictive value, and accuracy (P < 0.001, P = 0.001 and P = 0.047, respectively). CONCLUSION: The EC-NBI finding of capillaries in the rectal mucosa was strongly correlated with histological inflammation and aided in the differential diagnosis between active and inactive UC. PMID:25717245
Narrow-band Imager for Multi-Application Solar Telescope (MAST) at Udaipur Solar Observatory
NASA Astrophysics Data System (ADS)
Raja Bayanna, A.; Mathew, Shibu K.; Venkatakrishnan, Parameswaran; Srivastava, Nandita
Multi-Application Solar Telescope (MAST) is an off-axis Gregorian solar telescope of 50 cm clear aperture installed at the lake site of Udaipur solar observatory (USO). A narrow band imager is being developed for near simultaneous observations of the solar atmosphere at different heights. The heart of the system is two Fabry-Perot (FP) etalons working in tandem. The substrate of the etalons is made of Lithium Niobate electro-optic crystal. The filter is tuned by changing the refractive index of the crystal with the application of the voltage. It is important to know the voltage required per unit wavelength shift to tune the system for different wavelength regions for near simultaneous observations. A littrow spectrograph was set up to calibrate the FP etalons. The achieved spectral resolution with the spectrograph at 6173 ┼ is 35 m┼. Calibration is carried-out for the Fe I 6173 ┼, H-alpha 6563 ┼ and Ca K 8542 ┼. Free spectral range (FSR) obtained for FP1 and FP2 in tandem for 6173 ┼ is 6.7┼ and 150 m┼ respectively. Voltage range of the system allows us to scan the entire line profile of 6173 in the range of ▒220 m┼ with a sampling of 20 m┼. We also performed temperature tuning and voltage tuning of the system. Similar exercise is performed for other two wavelengths. Here we present the details of the calibration set-up and obtained parameters and first-light results of the system.
Detection of Mucosal Recurrent Nasopharyngeal Carcinomas After Radiotherapy With Narrow-Band Imaging Endoscopy
Wang, Wen-Hung [Department of Otolaryngology, Chang Gung Memorial Hospital at Chiayi and Chang Gung University College of Medicine, Taiwan (China); Lin, Yen-Chun, E-mail: email@example.com [Department of Otolaryngology, Chang Gung Memorial Hospital at Chiayi and Chang Gung University College of Medicine, Taiwan (China); Chen, Wen-Cheng; Chen, Miao-Fen [Department of Radiation Oncology, Chang Gung Memorial Hospital at Chiayi and Chang Gung University College of Medicine, Taiwan (China); Chen, Chih-Cheng [Department of Hematology and Oncology, Chang Gung Memorial Hospital at Chiayi and Chang Gung University College of Medicine, Taiwan (China); Lee, Kam-Fai [Department of Pathology, Chang Gung Memorial Hospital at Chiayi and Chang Gung University College of Medicine, Taiwan (China)
Purpose: This study evaluated the feasibility of screening mucosal recurrent nasopharyngeal carcinoma with narrow-band imaging (NBI) endoscopy. Methods and Materials: One hundred and six patients were enrolled. All patients underwent conventional white-light (WL) endoscopic examination of the nasopharynx followed by NBI endoscopy. Biopsies were performed if recurrence was suspected. Results: We identified 32 suspected lesions by endoscopy in WL and/or NBI mode. Scattered brown spots (BS) were identified in 22 patients, and 4 of the 22 who had negative MRI findings were histopathologically confirmed to be neoplasias that were successfully removed via endoscopy. A comparison of the visualization in NBI closer view corresponded to histopathological findings in 22 BS, and the prevalence rates of neoplasias in tail signs, round signs, and irregularities signs were 0% (0/6), 0% (0/7), and 44.4% (4/9), respectively (p = 0.048). The sensitivity, specificity, and diagnostic capability were 37.5%, 92.9% and 0.652 for WL, 87.5%, 74.5% and 0.810 for NBI, and 87.5%, 87.8%, and 0.876 for NBI closer view, respectively. NBI closer view was effective in increasing specificity compared with NBI alone (87.8% vs. 74.5%, p < 0.05), and in increasing sensitivity and diagnostic capability compared to WL alone (87.5% vs. 37.5%, p < 0.05; 0.876 vs. 0.652, p = 0.0001). Conclusions: Although NBI in endoscopy can improve sensitivity of mucosal recurrent nasopharyngeal neoplasias, false-positive (nonneoplasia BS) results may be obtained in areas with nonspecific inflammatory changes due to postradiation effects. NBI closer view not only can offer a timely, convenient, and highly reliable assessment of mucosal recurrent nasopharyngeal carcinoma, it can also make endoscopic removal possible.
Assessing the Temperature Dependence of Narrow-Band Raman Water Vapor Lidar Measurements: A Practical Approach
NASA Technical Reports Server (NTRS)
Whiteman, David N.; Venable, Demetrius D.; Walker, Monique; Cardirola, Martin; Sakai, Tetsu; Veselovskii, Igor
Narrow-band detection of the Raman water vapor spectrum using the lidar technique introduces a concern over the temperature dependence of the Raman spectrum. Various groups have addressed this issue either by trying to minimize the temperature dependence to the point where it can be ignored or by correcting for whatever degree of temperature dependence exists. The traditional technique for performing either of these entails accurately measuring both the laser output wavelength and the water vapor spectral passband with combined uncertainty of approximately 0.01 nm. However, uncertainty in interference filter center wavelengths and laser output wavelengths can be this large or larger. These combined uncertainties translate into uncertainties in the magnitude of the temperature dependence of the Raman lidar water vapor measurement of 3% or more. We present here an alternate approach for accurately determining the temperature dependence of the Raman lidar water vapor measurement. This alternate approach entails acquiring sequential atmospheric profiles using the lidar while scanning the channel passband across portions of the Raman water vapor Q-branch. This scanning is accomplished either by tilt-tuning an interference filter or by scanning the output of a spectrometer. Through this process a peak in the transmitted intensity can be discerned in a manner that defines the spectral location of the channel passband with respect to the laser output wavelength to much higher accuracy than that achieved with standard laboratory techniques. Given the peak of the water vapor signal intensity curve, determined using the techniques described here, and an approximate knowledge of atmospheric temperature, the temperature dependence of a given Raman lidar profile can be determined with accuracy of 0.5% or better. A Mathematica notebook that demonstrates the calculations used here is available from the lead author.
Meta-Analysis: Narrow Band Imaging for Diagnosis of Gastric Intestinal Metaplasia
Song, Jia; Zhang, Jixiang; Wang, Jun; Guo, Xufeng; Wang, Jing; Liu, Ya; Dong, Weiguo
Background Distinguishing early gastric cancer is challenging with current imaging techniques. Narrow band imaging (NBI) is effective for characterizing gastric lesions. Objectives The aim of this meta-analysis was to estimate the diagnostic accuracy of NBI in the gastric intestinal metaplasia (GIM). Methods We performed data analysis using Meta-DiSc (version 1.4) and STATA (version 11.0) software. To assess study quality and potential for bias, we used the Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) tool. Results Six studies involving 347 patients were included. On a per-patient basis, the sensitivity of NBI for diagnosis of GIM was 0.65 (95% CI ?=? 0.56¢0.74), and the specificity was 0.93 (95% CI ?=? 0.88¢0.97). The area under the summary receiver operating characteristic (SROC) curve was 0.8731. However, on a per-lesion basis, the sensitivity and specificity of NBI were 0.69 (95% CI ?=? 0.63¢0.74) and 0.91 (95% CI ?=? 0.87¢0.94), respectively. The SROC was 0.9009. The pooled sensitivity and specificity of magnification endoscopy (NBI-ME) were 0.76 (95% CI ?=? 0.61¢0.87) and 0.89 (95% CI ?=? 0.80¢0.94), respectively, on per-patient analysis. On a per-lesion basis, the pooled sensitivity and specificity of NBI-ME were 0.84 (95% CI ?=? 0.76¢0.89) and 0.93 (95% CI ?=? 0.89¢0.96), respectively. Heterogeneity was observed with an I2 for diagnostic odds ratio (DOR) of 0.01% and 85.8%, respectively. There was no statistical significance for the evaluation of publication bias. Conclusions Our meta-analysis shows that NBI is a useful tool for differential diagnosis of GIM with relatively low sensitivity and high specificity. PMID:24743566
Usefulness of magnifying endoscopy with narrow-band imaging for diagnosis of depressed gastric lesions
The usefulness of magnifying endoscopy with narrow-band imaging (ME-NBI) for the diagnosis of early gastric cancer is well known, however, there are no evaluation criteria. The aim of this study was to devise and evaluate a novel diagnostic algorithm for ME-NBI in depressed early gastric cancer. Between August, 2007 and May, 2011, 90 patients with a total of 110 depressed gastric lesions were enrolled in the study. A diagnostic algorithm was devised based on ME-NBI microvascular findings: microvascular irregularity and abnormal microvascular patterns (fine network, corkscrew and unclassified patterns). The diagnostic efficiency of the algorithm for gastric cancer and histological grade was assessed by measuring its mean sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy. Furthermore, inter- and intra-observer variation were measured. In the differential diagnosis of gastric cancer from non-cancerous lesions, the mean sensitivity, specificity, PPV, NPV, and accuracy of the diagnostic algorithm were 86.7, 48.0, 94.4, 26.7, and 83.2%, respectively. Furthermore, in the differential diagnosis of undifferentiated adenocarcinoma from differentiated adenocarcinoma, the mean sensitivity, specificity, PPV, NPV, and accuracy of the diagnostic algorithm were 61.6, 86.3, 69.0, 84.8, and 79.1%, respectively. For the ME-NBI final diagnosis using this algorithm, the mean ? values for inter- and intra-observer agreement were 0.50 and 0.77, respectively. In conclusion, the diagnostic algorithm based on ME-NBI microvascular findings was convenient and had high diagnostic accuracy, reliability and reproducibility in the differential diagnosis of depressed gastric lesions. PMID:24649321
Investigation of relationships among gastroesophageal reflux disease subtypes using narrow band imaging magnifying endoscopy
Lv, Jing; Liu, Dong; Ma, Shi-Yang; Zhang, Jun
AIM: To investigate the relationships among subtypes of gastroesophageal reflux disease (GERD) using narrow band imaging (NBI) magnifying endoscopy. METHODS: A reflux disease questionnaire was used to screen 120 patients representing the three subtypes of GERD (n = 40 for each subtypes): nonerosive reflux disease (NERD), reflux esophagitis (RE) and BarrettÆs esophagus (BE). NBI magnifying endoscopic procedure was performed on the patients as well as on 40 healthy controls. The demographic and clinical characteristics, and NBI magnifying endoscopic features, were recorded and compared among the groups. Targeted biopsy and histopathological examination were conducted if there were any abnormalities. SPSS 18.0 software was used for all statistical analysis. RESULTS: Compared with healthy controls, a significantly higher proportion of GERD patients had increased number of intrapapillary capillary loops (IPCLs) (78.3% vs 20%, P < 0.05), presence of microerosions (41.7% vs 0%, P < 0.05), and a non-round pit pattern below the squamocolumnar junction (88.3% vs 30%, P < 0.05). The maximum (228 ▒ 4.8 vs 144 ▒ 4.7, P < 0.05), minimum (171 ▒ 3.8 vs 103 ▒ 4.4, P < 0.05), and average (199 ▒ 3.9 vs 119 ▒ 3.9, P < 0.05) numbers of IPCLs/field were also significantly greater in GERD patients. However, comparison among groups of the three subtypes showed no significant differences or any linear trend, except that microerosions were present in 60% of the RE patients, but in only 35% and 30% of the NERD and BE patients, respectively (P < 0.05). CONCLUSION: Patients with GERD, irrespective of subtype, have similar micro changes in the distal esophagus. The three forms of the disease are probably independent of each other. PMID:24363532
Endoscopic diagnosis of cervical esophageal heterotopic gastric mucosa with conventional and narrow-band images
Cheng, Chi-Liang; Lin, Cheng-Hui; Liu, Nai-Jen; Tang, Jui-Hsiang; Kuo, Yen-Lin; Tsui, Yi-Ning
AIM: To compare the diagnostic yield of heterotopic gastric mucosa (HGM) in the cervical esophagus with conventional imaging (CI) and narrow-band imaging (NBI). METHODS: A prospective study with a total of 760 patients receiving a CI examination (mean age 51.6 years; 47.8% male) and 760 patients undergoing NBI examination (mean age 51.2 years; 45.9% male). The size of HGM was classified as small (1-5 mm), medium (6-10 mm), or large (> 1 cm). A standardized questionnaire was used to obtain demographic characteristics, social habits, and symptoms likely to be related to cervical esophageal HGM, including throat symptoms (globus sensation, hoarseness, sore throat, and cough) and upper esophageal symptoms (dysphagia and odynophagia) at least 3 mo in duration. The clinicopathological classification of cervical esophageal HGM was performed using the proposal by von Rahden et al. RESULTS: Cervical esophageal HGM was found in 36 of 760 (4.7%) and 63 of 760 (8.3%) patients in the CI and NBI groups, respectively (P = 0.007). The NBI mode discovered significantly more small-sized HGM than CI (55% vs 17%; P < 0.0001). For the 99 patients with cervical esophageal HGM, biopsies were performed in 56 patients; 37 (66%) had fundic-type gastric mucosa, and 19 had antral-type mucosa. For the clinicopathological classification, 77 patients (78%) were classified as HGM?I?(asymptomatic carriers); 21 as HGM II (symptomatic without morphologic changes); and one as HGM III (symptomatic with morphologic change). No intraepithelial neoplasia or adenocarcinoma was found. CONCLUSION: NBI endoscopy detects more cervical esophageal HGM than CI does. Fundic-type gastric mucosa constitutes the most common histology. One-fifth of patients have throat or dysphagic symptoms. PMID:24415878
Audiogram of a harbor porpoise (Phocoena phocoena) measured with narrow-band frequency-modulated signals.
Kastelein, Ronald A; Bunskoek, Paulien; Hagedoorn, Monique; Au, Whitlow W L; de Haan, Dick
The underwater hearing sensitivity of a two-year-old harbor porpoise was measured in a pool using standard psycho-acoustic techniques. The go/no-go response paradigm and up-down staircase psychometric method were used. Auditory sensitivity was measured by using narrow-band frequency-modulated signals having center frequencies between 250 Hz and 180 kHz. The resulting audiogram was U-shaped with the range of best hearing (defined as 10 dB within maximum sensitivity) from 16 to 140 kHz, with a reduced sensitivity around 64 kHz. Maximum sensitivity (about 33 dB re 1 microPa) occurred between 100 and 140 kHz. This maximum sensitivity range corresponds with the peak frequency of echolocation pulses produced by harbor porpoises (120-130 kHz). Sensitivity falls about 10 dB per octave below 16 kHz and falls off sharply above 140 kHz (260 dB per octave). Compared to a previous audiogram of this species (Andersen, 1970), the present audiogram shows less sensitive hearing between 2 and 8 kHz and more sensitive hearing between 16 and 180 kHz. This harbor porpoise has the highest upper-frequency limit of all odontocetes investigated. The time it took for the porpoise to move its head 22 cm after the signal onset (movement time) was also measured. It increased from about 1 s at 10 dB above threshold, to about 1.5 s at threshold. PMID:12141360
AVHRR Surface Temperature and Narrow-Band Albedo Comparison with Ground Measurements for the Greenland Ice Sheet
NASA Technical Reports Server (NTRS)
Haefliger, M.; Steffen, K.; Fowler, C.
An ice-surface temperature retrieval algorithm for the Greenland ice sheet was developed using NOAA 11 thermal radiances from channels 4 and 5. Temperature, pressure and humidity profiles, cloud observations and skin temperatures from the Swiss Federal Institute of Technology (ETH) camp, located at the equilibrium line altitude at 49 deg17 min W, 69 deg 34 min N, were used in the LOWTRAN 7 model. Through a statistical analysis of daily clear sky profiles, the coefficients that correct for the atmospheric effects were determined for the ETH-Camp field season (May to August). Surface temperatures retrieved by this method were then compared against the in situ observations with a maximum difference of 0.6 K. The NOAA 11 narrow-band planetary albedo values for channels 1 and 2 were calculated using pre-launch calibration coefficients. Scattering and absorption by the atmosphere were modelled with LOWTRAN 7. Then, narrow-band albedo values for the AVHRR visible and near infrared channels were compared with in situ high resolution spectral reflectance measurements. In the visible band (580-680 nm), AVHRR-derived narrow-band albedo and the in situ measurements corrected with radiative transfer model LOWTRAN 7 showed a difference of less than 2%. For the near infrared channel (725-1100 nm) the difference between the measured and modelled narrow-band albedo was 14%. These discrepancies could be either the result of inaccurate aerosol scattering modelling (lack of the in situ observation), or the result of sensor drift due to degradation.
Band limited emission with central frequency around 2 Hz accompanying powerful cyclones
NASA Technical Reports Server (NTRS)
Troitskaia, V. A.; Shepetnov, K. S.; Dvobnia, B. D.
It has been found that powerful cyclones are proceeded, accompanied and followed by narrow band electromagnetic emission with central frequency around 2 Hz. It is shown that the signal from this emission is unique and clearly distinguishable from known types of magnetic pulsations, spectra of local thunderstorms, and signals from industrial sources. This emission was first observed during an unusually powerful cyclone with tornadoes in the western European part of the Soviet Union, which passed by the observatory of Borok from south to north-east. The emission has been confirmed by analysis of similar events in Antarctica. The phenomenon described presents a new aspect of interactions of processes in the lower atmosphere and the ionosphere.
PMD-insensitive OSNR monitoring based on polarization-nulling with off-center narrow-band filtering
Man-Hong Cheung; Lian-Kuan Chen; Chun-Kit Chan
We propose and experimentally demonstrate the use of polarization-nulling with off-center narrow-band filtering to realize a new polarization-mode dispersion (PMD)-insensitive in-band optical signal-to-noise ratio monitoring scheme. When applied to a 39.81-Gb\\/s 2.5-ps full-width at half-maximum return-to-zero on-off keyed optical time-division-multiplexing system with 10and 20-ps differential group delay, the monitoring errors were reduced from >20 dB to <0.9 and <1.6 dB,
Barrett's adenocarcinoma in long-segment Barrett's esophagus successfully detected by narrow-band imaging with magnifying endoscopy.
Morita, Yoshinori; Tanaka, Shinwa; Toyonaga, Takashi; Azuma, Takeshi
Conventionally, long-segment Barrett's esophagus (LSBE) has been considered a high-risk background for the occurrence of Barrett's adenocarcinoma in Western countries, and random biopsy has been proposed for surveillance, aiming to detect early cancer. However, accurate detection of a lesion and diagnosis of the expansion are difficult by this blind method. Herein, we report a case of early Barrett's adenocarcinoma derived from LSBE that was successfully detected by narrow-band imaging with magnifying endoscopy. PMID:23617678
Five years of Project META - an all-sky narrow-band radio search for extraterrestrial signals
Paul Horowitz; Carl Sagan
We have conducted a five-year search of the northern sky (delta between 30 and 60 deg) for narrow-band radio signals near the 1420 MHz line of neutral hydrogen, and its second harmonic, using an 8.4 x 10 exp 6 channel Fourier spectrometer of 0.05 Hz resolution and 400 kHz instantaneous bandwidth. The observing frequency was corrected both for motions with
Design of optical thin film systems for ultraviolet narrow-band interference filters based on needle optimization technique
Guanliang Peng; Jiankun Yang; Honghui Jia; Shengli Chang; Juncai Yang
Solar blind ultraviolet communication systems can provide short to medium range non line-of-sight and line-of-sight links which are covert and insensitive to meteorological conditions. These unique properties endow solar blind ultraviolet communication systems increasing applications. While optical filters are key components of these solar blind ultraviolet communication systems. Although filters can be designed in different forms, thin-film interference narrow-band filters
Spectral evolution and extreme value analysis of non-linear numerical simulations of narrow band random surface gravity waves
H. Socquet-Juglard; K. B. Dysthe; K. Trulsen; J. Liu; H. E. Krogstad
Numerical simulations of a narrow band gaussian spectrum of random surface gravity waves have been carried out in two and three spatial dimensions [7]. Different types of non-linear Schr&{uml;o}dinger equations, [1] and [4], have been used in these simulations. Simulations have now been carried with a JONSWAP spectrum associated with a spreading function of the type cosine-squared [5]. The evolution
A case of small early gastric cancer that was successfully detected by narrow band imaging magnifying endoscopy.
Morita, Yoshinori; Fujiwara, Shoko; Tanaka, Shinwa; Toyonaga, Takashi; Azuma, Takeshi
Endoscopic diagnosis of gastric cancer is very often made by conventional white light endoscopy and/or by indigo carmine chromoendoscopy. However, with this method it is difficult to detect and demarcate a small lesion affected by inflammation or a biopsy procedure. We considered it is useful for diagnosis of such small cancers to observe a lesion with a magnifying endoscope combined with a narrow band imaging system. PMID:21535210
Magnifying narrow-band imaging with acetic acid to diagnose early colorectal cancer
Goto, Norihiro; Kusaka, Toshihiro; Tomita, Yumi; Tanaka, Hideyuki; Itokawa, Yoshio; Koshikawa, Yorimitsu; Yamaguchi, Daisuke; Nakai, Yoshitaka; Fujii, Shigehiko; Kokuryu, Hiroyuki
AIM: To evaluate the diagnostic characteristics of magnifying endoscopy with acetic acid spray and narrow-band imaging (MA-NBI) for early colorectal cancer. METHODS: We conducted a prospective study to evaluate the diagnostic characteristics of MA-NBI in differentiating early colorectal adenocarcinomas from adenomas. To compare the results, we used magnifying endoscopy with NBI (M-NBI) and magnifying endoscopy with crystal violet staining (M-CV). The study was performed in 2 phases. In phase 1, 10 colonoscopists at our institution were shown still photographs of 35 colorectal polyps (24 adenocarcinomas and 11 adenomas) in M-NBI, MA-NBI, and M-CV. They made diagnostic predictions using a five-grade scoring evaluation. We plotted receiver operating characteristic curves and compared the areas under the curves (AUCs). In phase 2, colorectal polyps measuring ? 8 mm were prospectively enrolled. During real-time colonoscopy, one of the 7 colonoscopists scored the lesion as an adenocarcinoma or an adenoma and assigned a level of confidence to the prediction (high or low). We calculated the accuracy, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for each method and compared the proportions of high-confidence predictions. RESULTS: In phase 1, the mean ▒ SD AUCs were 0.64 ▒ 0.031 in M-NBI, 0.71 ▒ 0.066 in MA-NBI, and 0.76 ▒ 0.059 in M-CV (P < 0.05 for M-NBI vs MA-NBI, P < 0.001 for M-NBI vs M-CV, and not significant for MA-NBI vs M-CV). In phase 2, 84 patients with 91 lesions (46 adenocarcinomas and 45 adenomas) were enrolled. The diagnostic characteristics were as follows: 73% accuracy, 85% sensitivity, 60% specificity, 68% PPV, and 79% NPV in M-NBI; 73% accuracy, 80% sensitivity, 64% specificity, 70% PPV, and 76% NPV in MA-NBI; and 73% accuracy, 83% sensitivity, 62% specificity, 69% PPV, and 78% NPV in M-CV. The proportions of high-confidence predictions were 57% in M-NBI, 75% in MA-NBI, and 76% in M-CV (P < 0.005 for M-NBI vs MA-NBI, P < 0.0005 for M-NBI vs M-CV, and P = 1.0 for MA-NBI vs M-CV). CONCLUSION: MA-NBI is useful for differentiating early colorectal adenocarcinomas from adenomas. PMID:25473188
Broad-band transmission spectrum and K-band thermal emission of WASP-43b as observed from the ground
NASA Astrophysics Data System (ADS)
Chen, G.; van Boekel, R.; Wang, H.; Nikolov, N.; Fortney, J. J.; Seemann, U.; Wang, W.; Mancini, L.; Henning, Th.
Aims: WASP-43b is the closest-orbiting hot Jupiter, and it has high bulk density. It causes deep eclipse depths in the system's light curve in both transit and occultation that is attributed to the cool temperature and small radius of its host star. We aim to secure a broad-band transmission spectrum and to detect its near-infrared thermal emission in order to characterize its atmosphere. Methods: We observed one transit and one occultation event simultaneously in the g', r', i', z', J, H, K bands using the GROND instrument on the MPG/ESO 2.2-m telescope, where the telescope was heavily defocused in staring mode. After modeling the light curves, we derived wavelength-dependent transit depths and flux ratios and compared them to atmospheric models. Results: From the transit event, we have independently derived WASP-43's system parameters with high precision and improved the period to be 0.81347437(13) days based on all the available timings. No significant variation in transit depths is detected, with the largest deviations coming from the i'-, H-, and K-bands. Given the observational uncertainties, the broad-band transmission spectrum can be explained by either (i) a flat featureless straight line that indicates thick clouds; (ii) synthetic spectra with absorption signatures of atomic Na/K, or molecular TiO/VO that in turn indicate cloud-free atmosphere; or (iii) a Rayleigh scattering profile that indicates high-altitude hazes. From the occultation event, we detected planetary dayside thermal emission in the K-band with a flux ratio of 0.197 ▒ 0.042%, which confirms previous detections obtained in the 2.09 ?m narrow band and KS-band. The K-band brightness temperature 1878+108-116 K favors an atmosphere with poor day- to nightside heat redistribution. We also have a marginal detection in the i'-band (0.037+0.023-0.021%), corresponding to TB = 2225+139-225 K, which is either a false positive, a signature of non-blackbody radiation at this wavelength, or an indication of reflective hazes at high altitude. Based on observations collected with the Gamma Ray Burst Optical and Near-Infrared Detector (GROND) on the MPG/ESO 2.2-m telescope at La Silla Observatory, Chile. Program 088.A-9016 (PI: Chen).Photometric time series are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://188.8.131.52) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/563/A40
A Novel Technique for Narrow-Band Tunable Filter Photometry to Enable Ground-Based Detection of Earth-Sized Exoplanets
NASA Astrophysics Data System (ADS)
Kimock, Benjamin; Col¾n, Knicole; Pepper, Joshua
We present a novel technique for the removal of sky rings from narrow-band photometry, which arise due to atmospheric OH emission. Our goal is to achieve very high-precision ground-based photometry to enable detection of small transit or occultation signals from exoplanets. We demonstrate our technique on narrow-band photometry of the super-Earth-size transiting planet CoRoT-7b acquired with the OSIRIS tunable filter imager on the 10.4-meter Gran Telescopio Canarias. Without removing sky rings, we do not detect a transit of CoRoT-7b at any significance, but after removing sky rings with our technique, we detect a transit at a significance of 3.2-sigma. Our detection of the transit suggests that this technique can enable ground-based detection of exoplanets with transit or occultation depths on the order of 0.1 mmag. At the time of writing, we believe this to be the first ground-based detection of a transit of a super-Earth orbiting a Sun-like star. This implies that the characterization of Earth-sized planets discovered by space-based missions like Kepler and the future TESS mission may be possible from the ground.
Simultaneous dual band laser emission from two conformations of DAMC
NASA Astrophysics Data System (ADS)
Masilamani, V.; Chandrasekar, V.; Sivaram, B. M.; Sivasankar, B.; Natarajan, S.
7-Diethyl amino-4-methyl coumarin (DAMC) exhibits amplified spontaneous emission (ASE) in two distinct bands, one around 425 nm and another around 450 nm in certain aprotic solvents like chloroform, p-dioxane, n-butyl acetate, etc. Experimental investigations indicate that the longer wavelength band is apparently due to the twisted intramolecular charge transfer conformation of the dye (formed predominantly in the excited state and) stabilized by the complex formation with the solvent.
Cosmic Star Formation History to z=1 from a Narrow Emission Line Selected Tunable Filter Survey
Karl Glazebrook; Jeffrey Tober; Scott Thomson; Joss Bland-Hawthorn; Roberto Abraham
We report the results of a deep 3D imaging survey of the Hubble Deep Field North using the Taurus Tunable Filter and the William Herschel Telescope. This survey was designed to search for new line emitting populations of objects missed by other techniques and to measure the cosmic star-formation rate density from a line-selected survey. We observed in three contiguous sequences of narrow band slices in the 7100, 8100 and 9100A regions of the spectrum, corresponding to a cosmological volume of up to 1000 Mpc^3 at z=1, down to a flux limit of 2x 10^-17 ergs cm^-2 s^-1. The survey is deep enough to be highly complete for low line luminosity galaxies. Cross-matching with existing spectroscopy in the field results in a small line-luminosity limited sample, with very highly redshift identification completeness containing seven [OII], Hbeta and Halpha emitters over the redshift range 0.3 - 0.9. Treating this as a direct star-formation rate selected sample we estimate the star-formation history of the Universe to z=1. We find no evidence for any new population of line emitting objects contributing significantly to the cosmological star-formation rate density. Rather from our complete narrow-band sample we find the star-formation history is consistent with earlier estimates from broad-band imaging surveys and other less deep line-selected surveys.
Clinicopathological features of narrow-band imaging endoscopy and immunohistochemistry in ultraminute esophageal squamous neoplasms.
Goda, K; Dobashi, A; Yoshimura, N; Chiba, M; Fukuda, A; Nakao, Y; Ohya, T R; Sasaki, Y; Kato, M; Aihara, H; Sumiyama, K; Toyoizumi, H; Kato, T; Tajiri, H; Ikegami, M
To reveal clinicopathological features of narrow-band imaging (NBI) endoscopy and immunohistochemistry in ultraminute esophageal squamous neoplasms. If a lesion diameter was smaller or same compared with a width of closed biopsy forceps, a lesion was defined to be an ultraminute lesion. Twenty-five consecutive patients with 33 ultraminute esophageal lesions that were removed by endoscopic mucosal resection were included in the present study. We conducted two questionnaire surveys of six endoscopists by their retrospective review of endoscopic still images. The six endoscopists evaluated the endoscopic findings of the ultraminute lesions on still images taken by conventional white-light imaging endoscopy and non-magnified NBI endoscopy in the first questionnaire, and taken by magnified NBI endoscopy in the second questionnaire. An experienced pathologist who was unaware of any endoscopic findings made histological diagnosis and evaluated immunoexpression of p53 and Ki67. The 33 ultraminute lesions were all determined to be either 11 high-grade intraepithelial neoplasias (HGIENs) or 22 low-grade intraepithelial neoplasias (LGIENs). The tumor diameters were histologically confirmed to be <3?mm. All of the ultraminute tumors were visualized as unstained areas and brownish areas by real-time endoscopy with Lugol dye staining and non-magnified NBI endoscopy, respectively. All of the ultraminute IENs were visualized as brownish areas by real-time non-magnified NBI endoscopy. Three of the 25 patients with the ultraminute IENs (12%) had multiple brownish areas (more than several areas) in the esophagus on real-time non-magnified NBI endoscopy. All of the ultraminute IENs were visualized as unstained areas by real-time Lugol chromoendoscopy. Twenty of the 25 patients (80%) had multiple unstained areas (more than several areas) in the esophagus on real-time Lugol chromoendoscopy. The first questionnaire survey revealed that a significantly higher detection rate of the ultraminute IENs on non-magnified NBI endoscopy images compared with conventional white-light imaging endoscopy ones (100% vs. 72%, respectively: P < 0.0001). The second questionnaire survey revealed that presence rates of any magnified NBI endoscopy findings were not significantly different between HGIENs and LGIENs. Proliferation, dilation, and various shapes of intrapapillary capillary loops indicated remarkably high presence rates of more than 90% in both HGIENs and LGIENs. Six of 22 LGIENs (27%) and 3 of 11 HGIENs (27%) show a positive expression for p53. None of peri-IEN epithelia was positive for p53. A mean of Ki67 labeling index of LGIENs was 33% and that of HGIENs 36%. Ki67 labeling index was significantly greater in the LGIENs and HGIENs compared with that in the peri-IEN epithelia. There were no significant differences in p53 expression and Ki67 labeling index between the HGIENs and LGIENs. Non-magnified/magnified NBI endoscopy could facilitate visualization and characterization of ultraminute esophageal squamous IENs. The ultraminute HGIENs and LGIENs might have comparable features of magnified NBI endoscopy and immunohistochemistry. PMID:23796261
ALEXIS (Array of Low-Energy X-Ray Imaging Sensors): A narrow-band survey/monitor of the ultrasoft x-ray sky
Priedhorsky, W.C.; Bloch, J.J.; Cordova, F.; Smith, B.W.; Ulibarri, M.; Chavez, J.; Evans, E.; Seigmund, O.H.W.; Marshall, H.; Vallerga, J.
Los Alamos and Sandia National Laboratories are building an ultrasoft X-ray monitor experiment. This experiment, called ALEXIS (Array of Low-Energy X-Ray Imaging Sensors), consists of six compact normal-incidence telescopes. ALEXIS will operate in the range 70--110 eV. The ultrasoft X-ray/EUV band is nearly uncharted territory for astrophysics. ALEXIS, with its wide fields-of-view and well-defined wavelength bands, will complement the upcoming NASA Extreme Ultraviolet Explorer and ROSAT EUV Wide Field Camera, which are sensitive broad-band survey experiments. The program objectives of ALEXIS are to (1) demonstrate the feasibility of a wide field-of-view, normal incidence ultrasoft X-ray telescope system and (2) to determine ultrasoft X-ray backgrounds in the space environment. As a dividend, ALEXIS will pursue the following scientific objectives: (1) to map the diffuse background, with unprecedented angular resolution, in several emission-line bands, (2) to perform a narrow-band survey of point sources, (3) to search for transient phenomena in the ultrasoft X-ray band, and (4) to provide synoptic monitoring of variable ultrasoft X-ray sources such as cataclysmic variables and flare stars. ALEXIS is designed to be flown on a small autonomous payload carrier (a minisat) that could be launched from any expendable launch vehicle. The experiment weighs 100 pounds, draws 40 watts, and produces 10 kbps of data. It can be flown in any low earth orbit. Onboard data storage allows operation and tracking from a single ground station at Los Alamos. 57 refs., 12 figs.
Symmetry-protected mode coupling near normal incidence for narrow-band transmission filtering in a dielectric grating
NASA Astrophysics Data System (ADS)
Foley, J. M.; Young, S. M.; Phillips, J. D.
A narrow-band transmission filter is demonstrated near normal incidence that operates through relaxation of supported-mode selection rules and is explained in the context of group theory. We calculated the transverse magnetic and transverse electric dispersion relations of a dielectric grating in the subwavelength and near-wavelength region using finite element modal analysis and determine the modes' corresponding irreducible representations. Coupling to select transverse magnetic modes at normal incidence is optimized to yield broadband high reflectance that acts as the background for the transmission filter. While some modes couple at normal incidence, others are shown to remain inaccessible due to symmetry mismatch. Away from normal incidence, the reduced symmetry relaxes the selection rules, enabling weak coupling between the incident field and these symmetry-protected modes. This weak coupling produces narrow transmission bands within the opaque background. Furthermore, by choosing the plane of incidence to include or exclude the grating periodicity, we show that orthogonal mode sets can independently be selected to couple to the incident light, yielding separate transmission bands. This spectral filtering is experimentally demonstrated with a suspended silicon grating in the infrared spectrum (7-14?m), which agrees well with simulated transmittance spectra and modal analysis.
Enhancing the monitoring sensitivity of DOP-based OSNR monitors in high OSNR region using off-center narrow-band optical filtering
Guo-Wei Lu; Lian-Kuan Chen
Recently, OSNR monitoring based on the measurement of degree of polarization (DOP) has attracted much attention, thanks to its simplicity and high efficiency. However, the OSNR monitoring sensitivity is quite poor in the high OSNR region, resulting in high estimation error and narrow dynamic range. In this paper, we propose and experimentally demonstrate a narrow-band off-center optical filtering technique for
Statistics of narrow-band single photons for quantum memories generated by ultrabright cavity-enhanced parametric down-conversion.
Scholz, Matthias; Koch, Lars; Benson, Oliver
Narrow-band single photons represent an important resource for quantum memories due to their efficient interaction with atomic resonances. In this Letter, we report on the generation of photons with 3 MHz linewidth by cavity-enhanced parametric down-conversion and demonstrate direct proof of their single-photon character by detection of heralding idler photons. Compared to a Poissonian source, a suppression of higher-order photon numbers by nearly 2 orders of magnitude could be achieved. Moreover, the brightness of our source exceeds previous realizations by more than a factor of 100. PMID:19257589
A Mild Case of Adult-Onset Keratosis Lichenoides Chronica Successfully Treated with Narrow-Band UVB Monotherapy
Nomura, Takashi; Toichi, Eiko; Miyachi, Yoshiki; Kabashima, Kenji
Keratosis lichenoides chronica (KLC) is a rare keratotic disorder of unknown origin. Effective treatment has not been established yet. Here, we present adult-onset KLC, which was treated by narrow-band ultraviolet B (NB-UVB) monotherapy. Although NB-UVB was reported to be effective for pediatric-onset KLC, it has not been clear if this regimen is also useful for adult-onset type because pediatric-onset KLC is suggested to be different in nature. We assume that KLC is treatable by NB-UVB regardless of the age of the patient. PMID:23185159
Optical Observations of the Nearby Galaxy IC342 with Narrow Band [SII] and H_alpha Filters. I
NASA Astrophysics Data System (ADS)
Vucetic, M. M.; Arbutina, B.; Urosevic, D.; Dobardzic, A.; Pavlovic, M. Z.; Pannuti, T. G.; Petrov, N.
We present observations of a portion of the nearby spiral galaxy IC342 using narrow band [SII] and H? filters. These observations were carried out in November 2011 with the 2m RCC telescope at Rozhen National Astronomical Observatory in Bulgaria. In this paper we report coordinates, diameters, H? and [SII] fluxes for 203 HII regions detected in two fields of view in IC342 galaxy. The number of detected HII regions is 5 times higher than previously known in these two parts of the galaxy.
Observation of lymphangioma of the duodenum by a magnifying endoscope with a narrow-band imaging system.
Iwamuro, Masaya; Kawai, Yoshinari; Takata, Katsuyoshi; Okada, Hiroyuki; Yamamoto, Kazuhide
Among duodenal tumors, lymphangioma is relatively infrequent. In this case report, we describe the case of a 65-year-old Japanese man with duodenal lymphangioma diagnosed by esophagogastroduodenoscopy. Endoscopically, the tumor appeared as a soft submucosal tumor with white spots. When the white spots were grasped by biopsy forceps, milky liquid exuded from the tumor. Additionally, observation by a magnifying endoscope with narrow-band imaging revealed elongated microvessels on the surface. We speculated that this feature was formed because the duodenal villi were dilated and the microvessels were stretched due to the retention of chyle. These endoscopic findings are key features in the diagnosis of duodenal lymphangioma. PMID:23798913
Assessment of MODIS Thermal Emissive Band On-Orbit Calibration
NASA Technical Reports Server (NTRS)
Chang, Tiejun; Xiong, Xiaoxiong
Sixteen Moderate Resolution Imaging Spectroradiometer thermal emissive bands (TEBs) cover the wavelength from 3.75 to 14.24 m. TEB calibration uses data collected from the detector responses to the onboard blackbody (BB) and space view. The BB was designed to operate either at a constant temperature for detector linear gain calibration or at temperatures varying from ambient ( 270 K) to 315 K for on-orbit characterization of nonlinear coefficients. In this paper, we assess TEB on-orbit calibration performance in two aspects: One is to review the calibration trending on the orbital, daily, and multiyear timescales, and the other is to analyze the on-orbit calibration radiance uncertainty and its impact on the calibration. The calibration trending confirms the detector response dependence on the instrument temperature. The temperature trending and prelaunch characterization provide the basis for determining the calibration radiance source temperature range and uncertainties. An analytical approach was used to assess the impacts of onboard radiance uncertainties. The BB emission uncertainty, resulting from the temperature measurement error and emissivity uncertainty, causes a calibration uncertainty up to 0.3%, a value decreasing with the band wavelength. The BB nonblackness effect is analyzed and found to be insignificant. For the band with the lowest BB emissivity, the nonblackness affects the calibration radiance by less than 0.08%. The cavity emission uncertainty and the scan-mirror emission uncertainty both cause a less than 0.1% calibration uncertainty. The analysis of the nonlinear calibration coefficient uncertainty shows that its effect on the low Earth-view brightness-temperature range varies by band and is generally insignificant.
Commissioning results of the narrow-band beam position monitor system upgrade in the APS storage ring.
Singh, O.
When using a low emittance storage ring as a high brightness synchrotron radiation source, it is critical to maintain a very high degree of orbit stability, both for the short term and for the duration of an operational fill. A fill-to-fill reproducibility is an additional important requirement. Recent developments in orbit correction algorithms have provided tools that are capable of achieving a high degree of orbit stability. However, the performance of these feedback systems can be severely limited if there are errors in the beam position monitors (BPMs). The present orbit measurement and correction system at the APS storage ring utilizes 360 broad-band-type BPMs that provide turn-by-turn diagnostics and an ultra-stable orbit: < 1.8 micron rms vertically and 4.5 microns rms horizontally in a frequency band of 0.017 to 30 Hz. The effects of beam intensity and bunch pattern dependency on these BPMs have been significantly reduced by employing offset compensation correction. Recently, 40 narrow-band switching-type BPMs have been installed in the APS storage ring, two in each of 20 operational insertion device straight sections, bringing the total number of beam position monitors to 400. The use of narrow-band BPM electronics is expected to reduce sensitivity to beam intensity, bunch pattern dependence, and long-term drift. These beam position monitors are used for orbit correction/feedback and machine protection interlocks for the insertion device beamlines. The commissioning results and overall performance for orbit stability are provided.
Perfect narrow-band absorber based on a monolayer of metallodielectric microspheres
Dyachenko, P. N., E-mail: firstname.lastname@example.com; Petrov, A. Yu.; Eich, M. [Institute of Optical and Electronic Materials, Hamburg University of Technology, Eissendorfer Strasse 38, 21073 Hamburg (Germany)] [Institute of Optical and Electronic Materials, Hamburg University of Technology, Eissendorfer Strasse 38, 21073 Hamburg (Germany)
We have studied how two-dimensional arrays of metallodielectric core-shell microspheres on a metal substrate can efficiently absorb infrared electromagnetic radiation in a narrow wavelength range under normal incidence. Our simulations indicate that perfect absorption efficiencies can be achieved for resonance wavelengths. The influence of core-shell microspheres geometry and lattice geometry is studied on absorption properties. For wavelength from 1.2??m to 2.6??m, an optimal combination of sphere and core radius was obtained to provide perfect absorption which can be wavelength adjusted.
Five years of Project META - An all-sky narrow-band radio search for extraterrestrial signals
NASA Technical Reports Server (NTRS)
Horowitz, Paul; Sagan, Carl
We have conducted a five-year search of the northern sky (delta between 30 and 60 deg) for narrow-band radio signals near the 1420 MHz line of neutral hydrogen, and its second harmonic, using an 8.4 x 10 exp 6 channel Fourier spectrometer of 0.05 Hz resolution and 400 kHz instantaneous bandwidth. The observing frequency was corrected both for motions with respect to three astronomical inertial frames, and for the effect of Earth's rotation, which provides a characteristic changing Doppler signature for narrow-band signals of extraterrestrial origin. Among the 6 x 10 exp 13 spectral channels searched, we have found 37 candidate events exceeding the average detection threshold of 1.7 x 10 exp -23 W/sq m, none of which was detected upon reobservation. The strongest of these appear to be dominated by rare processor errors. However, the strongest signals that survive culling for terrestrial interference lie in or near the Galactic plane. We describe the search and candidate events, and set limits on the prevalence of supercivilizations transmitting Doppler-precompensated beacons at H I or its second harmonic. We conclude with recommendations for future searches, based upon these findings, and a description of our next-generation search system.
Autofluorescence imaging and narrow-band imaging for the detection of early neoplasia in patients with Barrett's esophagus.
Kara, M A; Bergman, J J
High-resolution endoscopy (HRE), magnifying endoscopy, auto-fluorescence endoscopy, and narrow-band imaging (NBI) are promising techniques that could improve the detection of early neoplasia and the efficacy of endoscopic surveillance in patients with Barrett's esophagus. HRE improves the detection of lesions by white light, and video autofluorescence imaging (AFI) may have additional value in terms of sensitivity. The strengths ofAFI are its high sensitivity and a high negative predictive value,while potential limitations are its moderate specificity and positive predictive value. NBI enhances the mucosal and vascular patterns (i. e. the mucosal morphology) without the need for chromoendoscopy. The mucosal morphology features may be used to distinguish early neoplasia from nondysplastic Barrett's esophagus. Magnification is required for optimal use of NBI,which is a limitation of this technique. NBI with magnifying endoscopy could, however, be used for targeted inspection of lesions detected first by HRE or AFI. This approach has been shown to reduce the false-positive rate associated with AFI while maintaining its high sensitivity. To date, AFI and NBI have been used separately in two different prototypes, but a prototype endoscope that incorporates all of these techniques has recently become available. It is expected that future refinement of the autofluorescence and narrow-band modules may further increase their diagnostic value and ultimately improve the effectiveness of surveillance of Barrett's esophagus. PMID:16802271
Narrow band defect luminescence from Al-doped ZnO probed by scanning tunneling cathodoluminescence
Russell, Kasey
.1063/1.3647622] Aluminum-doped zinc oxide (AZO) exhibits similar electronic properties to ZnO: a wide optical band gap (Eg of magnitude and the material is called a transparent conducting oxide (TCO). In order to best exploit AZO indium gallium zinc oxide films on flexible substrate by room- temperature deposition and post
Inter-band Tunnel Transistor Architecture using Narrow Gap Semiconductors S. Mookerjea, R. Krishnan, A. Vallett, T. Mayer and S. Datta
Yener, Aylin
Inter-band Tunnel Transistor Architecture using Narrow Gap Semiconductors S. Mookerjea, R. Krishnan University, University Park, PA 16802, USA The inter-band tunnel transistor (TFET) architecture features miniaturization of the silicon CMOS transistor technology, has resulted in an unprecedented increase in single
Emergent dimensional reduction of the spin sector in a model for narrow-band manganites
Liang, Shuhua [ORNL; Daghofer, Maria [ORNL; Dong, Shuai [Nanjing National Laboratory of Microstructures, Nanjing University, Nanjing; Sen, Cengiz [ORNL; Dagotto, Elbio R [ORNL
The widely used double-exchange model for manganites is shown to support various striped phases at filling fractions 1/n (n = 3, 4, 5, . . .), in the previously unexplored regime of narrow bandwidth and small Jahn-Teller coupling. Working in two dimensions, our main result is that these stripes can be individually spin flipped without a physically relevant change in the energy, i.e., we find a large ground-state manifold with nearly degenerate energies. The two-dimensional spin system thus displays an unexpected dynamically generated dimensional reduction into decoupled one-dimensional stripes, even though the electronic states remain two dimensional. Relations of our results with recent literature addressing compass models in quantum computing are discussed.
The infrared emission bands. III - Southern IRAS sources
NASA Technical Reports Server (NTRS)
Cohen, Martin; Tielens, A. G. G. M.; Bregman, Jesse; Witteborn, Fred C.; Allamandola, L. J.; Wooden, Diane H.; Rank, David M.
Airborne 5-8-micron spectra of southern IRAS sources are presented which display the strong PAH emission features. The sources studied include those in a previous paper (Cohen et al, 1986) and NGC 6302, HR 4049, and CPD -56 deg 8032. A good correlation is found between the intensity ratio of the 7.7-micron feature relative to the FIR dust continuum and nebular C/O ratio, supporting a carbonaceous carrier for these emission features. In addition, a weak PAH band is detected near 5.2 microns in several sources.
Electronic stopping power in a narrow band gap semiconductor from first principles
NASA Astrophysics Data System (ADS)
Ullah, Rafi; Corsetti, Fabiano; Sßnchez-Portal, Daniel; Artacho, Emilio
The direction and impact parameter dependence of electronic stopping power, along with its velocity threshold behavior, is investigated in a prototypical small-band-gap semiconductor. We calculate the electronic stopping power of H in Ge, a semiconductor with relatively low packing density, using time-evolving time-dependent density-functional theory. The calculations are carried out in channeling conditions with different impact parameters and in different crystal directions for projectile velocities ranging from 0.05 to 0.6 atomic units. The satisfactory comparison with available experiments supports the results and conclusions beyond experimental reach. The calculated electronic stopping power is found to differ in different crystal directions; however, strong impact parameter dependence is observed only in one of these directions. The distinct velocity threshold observed in experiments is well reproduced, and its nontrivial relation with the band gap follows a perturbation theory argument surprisingly well. This simple model is also successful in explaining why different density functionals give the same threshold even with substantially different band gaps.
Spectral imaging of the 3.3 and 11.3 micron emission bands in NGC 1333 - Discovery of spatially separate band emissions
NASA Technical Reports Server (NTRS)
Bregman, Jesse; Rank, David; Sandford, Scott A.; Temi, Pasquale
Spectral images in the 3.3 and 11.3 micron IR emission band around the star SVS 3 in NGC 1333 indicate that the two bands have their origin in different locations, rendering them useless in estimates of the sizes of the molecules emitting the bands. This is in keeping with the emission bands' generation by a mixture of variously sized polycyclic aromatic hydrocarbons (PAHs) whose smallest species have been dehydrogenated in the vicinity of SVS 3. Hot bands and overtone/combination bands may account for the 3.4-micron band, rather than molecular side-groups of the PAHs.
Star-formation in NGC 4038/4039 from broad- and narrow band photometry: Cluster Destruction?
Sabine Mengel; Matthew D. Lehnert; Niranjan Thatte; Reinhard Genzel
Accurately determining the star formation history in NGC 4038/4039 -- ``The Antennae'' is hampered by extinction. We therefore used near infrared images obtained with ISAAC at the VLT and with SOFI at the NTT to determine the recent star formation history in this merger. In combination with archival HST data, we determined ages, extinction and other parameters for single star clusters, and properties of the cluster population as a whole. About 70% of the K_s-band detected star clusters with masses >= 10^5 M_sun are younger than 10 Myrs (approximately an e-folding time for cluster ages), which we interpret as evidence for rapid dissolution but not free expansion. The total mass of K-band selected clusters is about 5-10x10^8 M_sun and represents about 3-6% of the total molecular gas. This takes into account only the detected clusters and in view of the rapid dissolution means that this is only a lower limit to the total mass of stars produced in clusters during the burst. Studies of cluster formation in other galaxies recently suggested short cluster dissolution timescales, too, which means that star formation rates may have been severely underestimated in the past. Extinction is strongly variable and very high in some regions, but around A_V=1.3 mag on average. Even though most clusters are detected at least in I-band, only the information about individual cluster ages and extinction allows to avoid uncertainties of orders of magnitude in star formation rate estimates determined from optical fluxes. From the distribution of individual cluster extinction vs. age, which is significantly higher for clusters below 8-9 Myr than for older clusters, we infer that this is the time by which a typical cluster blows free of its native dust cocoon.
A six-pole narrow-band high temperature superconducting filter with wide stop-band response at P-band
NASA Astrophysics Data System (ADS)
Gong, Liming; Wei, Bin; Zhang, Ying; Zhang, Xiaoping; Guo, Xubo; Zhang, Guoyong; Cao, Bisong
A quarter-wavelength stepped impedance resonator (QWSIR) is proposed for high temperature superconducting (HTS) filter, offering wide stop-band performance. A six-pole P-band HTS filter with QWSIRs was designed and fabricated. The filter has a fractional bandwidth of 0.8% at 516 MHz and shows the lowest spurious frequency at about 2.15 GHz. The measured results of the HTS filter are in good agreement with simulations.
Effects of laser source parameters on the generation of narrow band and directed laser ultrasound
NASA Technical Reports Server (NTRS)
Spicer, James B.; Deaton, John B., Jr.; Wagner, James W.
Predictive and prescriptive modeling of laser arrays is performed to demonstrate the effects of the extension of array elements on laser array performance. For a repetitively pulsed laser source (the temporal laser array), efficient frequency compression is best achieved by detecting longitudinal waves off-epicenter in plates where the source size and shape directly influence the longitudinal wave shape and duration; the longitudinal array may be tailored for a given repetition frequency to yield efficient overtone energy compression into the fundamental frequency band. For phased arrays, apparent array directivity is heavily influenced by array element size.
Spectrally narrowed leaky waveguide edge emission and transient electrluminescent dynamics of OLEDs
Zhengqing, Gan
In summary, there are two major research works presented in this dissertation. The first research project (Chapter 4) is spectrally narrowed edge emission from Organic Light Emitting Diodes. The second project (Chapter 5) is about transient electroluminescent dynamics in OLEDs. Chapter 1 is a general introduction of OLEDs. Chapter 2 is a general introduction of organic semiconductor lasers. Chapter 3 is a description of the thermal evaporation method for OLED fabrication. The detail of the first project was presented in Chapter 4. Extremely narrowed spectrum was observed from the edge of OLED devices. A threshold thickness exists, above which the spectrum is narrow, and below which the spectrum is broad. The FWHM of spectrum depends on the material of the organic thin films, the thickness of the organic layers, and length of the OLED device. A superlinear relationship between the output intensity of the edge emission and the length of the device was observed, which is probably due to the misalignment of the device edge and the optical fiber detector. The original motivation of this research is for organic semiconductor laser that hasn't been realized due to the extremely high photon absorption in OLED devices. Although we didn't succeed in fabricating an electrically pumped organic laser diode, we made a comprehensive research in edge emission of OLEDs which provides valuable results in understanding light distribution and propagation in OLED devices. Chapter 5 focuses on the second project. A strong spike was observed at the falling edge of a pulse, and a long tail followed. The spike was due to the recombination of correlated charge pair (CCP) created by trapped carriers in guest molecules of the recombination zone. When the bias was turned off, along with the decreasing of electric field in the device, the electric field induced quenching decreases and the recombination rate of the CCP increases which result in the spike. This research project provides a profound understanding of the EL dynamics of OLED, and the theoretical model can fit and explain the experiment data quite well. For the edge emission, we focused on the spectrum and the relative intensity of the edge emission. In the future, more research can be done on the comparison of the intensity between the total edge emission and the surface emission which will give us a sense what fraction of light was trapped in the device. Micro structures can be integrated into the OLED such as DFB and DBR, the character of edge emission should be very interesting. For the transient spike, the CCP model can give a good explanation. But in the model, the effect of the electric field change is not included, because from the start point (t=0), we assume the mobility of carriers is a constant. If we consider the details of the change of the electric field, then when turning of the bias, the decrease of the electric field results in decrease of the carrier mobility and the dissociation rate. If we can add the electric field effect into the model, the whole theory will be more convincing.
Jupiter S-bursts: Narrow-band origin of microsecond subpulses
V. B. Ryabov; B. P. Ryabov; D. M. Vavriv; P. Zarka; R. Kozhin; V. V. Vinogradov; V. A. Shevchenko
We analyze the records of Jupiter's decameter radio emissions obtained during an Io-A S-burst storm on 15 March 2005. The observations were performed at the world's largest decameter array, UTR-2, which is equipped with a digital receiver capable of catching waveforms of duration ?3 s with temporal resolution defined by the sampling rate of ?66 MHz. A Hilbert transform based
Strong Narrow-Band Luminescence from Silicon-Vacancy Color Centers in Spatially Localized Sub-10 nm Nanodiamond.
Catledge, Shane A; Singh, Sonal
Discrete nanodiamond particles of 500 nm and 6 nm average size were seeded onto silicon substrates and plasma treated using chemical vapor deposition to create silicon-vacancy color centers. The resulting narrow-band room temperature photoluminescence is intense, and readily observed even for weakly agglomerated sub-10 nm size diamond. This is in contrast to the well-studied nitrogen-vacancy center in diamond which has luminescence properties that are strongly dependant on particle size, with low probability for incorporation of centers in sub-10 nm crystals. We suggest the silicon-vacancy center to be a viable alternative to nitrogen-vacancy defects for use as a biomarker in the clinically-relevant sub-10 nm size regime, for which nitrogen defect-related luminescent activity and stability is reportedly poor. PMID:21603120
Strong Narrow-Band Luminescence from Silicon-Vacancy Color Centers in Spatially Localized Sub-10 nm Nanodiamond
Catledge, Shane A.; Singh, Sonal
Discrete nanodiamond particles of 500 nm and 6 nm average size were seeded onto silicon substrates and plasma treated using chemical vapor deposition to create silicon-vacancy color centers. The resulting narrow-band room temperature photoluminescence is intense, and readily observed even for weakly agglomerated sub-10 nm size diamond. This is in contrast to the well-studied nitrogen-vacancy center in diamond which has luminescence properties that are strongly dependant on particle size, with low probability for incorporation of centers in sub-10 nm crystals. We suggest the silicon-vacancy center to be a viable alternative to nitrogen-vacancy defects for use as a biomarker in the clinically-relevant sub-10 nm size regime, for which nitrogen defect-related luminescent activity and stability is reportedly poor. PMID:21603120
Magnifying Endoscopy with Narrow Band Imaging to Determine the Extent of Resection in Transoral Robotic Surgery of Oropharyngeal Cancer
Tateya, Ichiro; Ishikawa, Seiji; Morita, Shuko; Ito, Hiroyuki; Sakamoto, Tatsunori; Murayama, Toshinori; Kishimoto, Yo; Hayashi, Tomomasa; Funakoshi, Makiko; Hirano, Shigeru; Kitamura, Morimasa; Morita, Mami; Muto, Manabu; Ito, Juichi
Transoral robotic surgery (TORS) is a less invasive treatment that is becoming popular all over the world. One of the most important factors for achieving success in TORS is the ability to determine the extent of resection during the procedure as the extent of resection in the laryngopharynx not only affects oncological outcomes but also directly affects swallowing and voice functions. Magnifying endoscopy with narrow band imaging (ME-NBI) is an innovative optical technology that provides high-resolution images and is useful in detecting early superficial pharyngeal cancers, which are difficult to detect by standard endoscopy. A 55-year-old male with superficial oropharyngeal cancer has been successfully treated by combining MB-NBI with TORS and MB-NBI was useful in determining the extent of resection. ME-NBI with TORS will make it possible to achieve a higher ratio of minimally invasive treatment in pharyngeal cancer. PMID:25574412
Faint Object Spectrograph Spectra of the UV Emission Lines in NGC 5558: Detection of Strong Narrow Components
NASA Technical Reports Server (NTRS)
Crenshaw, D. Michael; Boggess, Albert; Wu, Chi-Chao
Ultraviolet spectra of the Seyfert 1 galaxy NGC 5548 were obtained with the Faint Object Spectrograph (FOS) on the Hubble Space Telescope on 1992 July 5, when the UV continuum and broad emission lines were at their lowest ever observed level. The high resolution of the spectra, relative to previous UV observations, and the low state of NGC 5548 allow the detection and accurate measurement of strong narrow components of the emission lines of Ly alpha, C IV 1549, and C III 1909. Isolation of the UV narrow components enables a detailed comparison of narrow-line region (NLR) properties in Seyfert 1 and 2 galaxies, and removal of their contribution is important for studies of the broad-line region (BLR). Relative to the other narrow lines, C IV 1549 is much stronger in NGC 5548 than in Seyfert 2 galaxies, and Mg II 2798 is very weak or absent.
Use of narrow-band spectra to estimate the fraction of absorbed photosynthetically active radiation
NASA Technical Reports Server (NTRS)
Hall, Forrest G.; Huemmrich, Karl F.; Goward, Samuel N.
A novel approach is proposed for using high-spectral resolution imagers to estimate the fraction of photosynthetically active radiation adsorbed, f(apar), by vegetated land surfaces. In comparison to approaches using broad-band vegetation indices, the proposed method appears to be relatively insensitive to the reflectance of nonphotosynthetically active material beneath the canopy, such as leaf litter or soil. The method is based on a relationship between the second derivative of the reflectance vs wavelength function for terrestrial vegetation and f(apar). The relationship can be defined by the second derivatives in either of two windows, one in the visible region centered at 0.69 micron, another in the near-infrared region centered at 0.74 micron.
Mapping the large-scale structure around a z = 1.46 galaxy cluster in 3D using two adjacent narrow-band filters
NASA Astrophysics Data System (ADS)
Hayashi, Masao; Kodama, Tadayuki; Koyama, Yusei; Tadaki, Ken-ichi; Tanaka, Ichi; Shimakawa, Rhythm; Matsuda, Yuichi; Sobral, David; Best, Philip N.; Smail, Ian
We present a novel method to estimate accurate redshifts of star-forming galaxies by measuring the flux ratio of the same emission line observed through two adjacent narrow-band filters. We apply this method to our NB912 and new NB921 data taken with Suprime-Cam on the Subaru Telescope of a galaxy cluster, XMMXCS J2215.9-1738, at z = 1.46 and its surrounding structures. We obtain redshifts for 170 [O II] emission line galaxies at z ś 1.46, among which 41 galaxies are spectroscopically confirmed with Multi-Object Infrared Camera and Spectrograph and Fibre Multi Object Spectrograph on the Subaru mainly, showing an accuracy of ?((z - zspec)/(1 + zspec)) = 0.002. This allows us to reveal filamentary structures that penetrate towards the centre of the galaxy cluster and intersect with other structures, consistent with the picture of hierarchical cluster formation. We also find that the projected celestial distribution does not precisely trace the real distribution of galaxies, indicating the importance of the three-dimensional view of structures to properly identify and quantify galaxy environments. We investigate the environmental dependence of galaxy properties with local density, confirming that the median colour of galaxies becomes redder in higher density region, while the star formation rate of star-forming galaxies does not depend strongly on local environment in this structure. This implies that the star-forming activity in galaxies is truncated on a relatively short time-scale in the cluster centre.
T-shaped plasmonic array as a narrow-band thermal emitter or biosensor.
Chang, Yia-Chung; Wang, Chih-Ming; Abbas, Mohammed N; Shih, Ming-Hsiung; Tsai, Din Ping
A T-shaped plasmonic array is proposed for application as an effective thermal emitter or biosensor. The reflection and thermal radiation properties of a T-shaped array are investigated theoretically. The angular dependent reflectance spectrum shows a clear resonant dip at 0.36 eV for full polar angles. No other significant localized resonant mode is found in the investigated spectral range from 0.12 eV to 0.64 eV. According to the Kirchhoff's law, the thermal radiation of the proposed structure can lead to a sharp peak at 3.5 microm with low sideband emission. We have also found that the T-shaped structure filled with organic material such as PMMA with different thicknesses (10 nm -50 nm) can lead to significant shift of the resonance wavelength. Thus, the T-shaped structure can also be used as a good sensor for organic materials. PMID:19654760
Methane Band and Continuum Band Imaging of Titan's Atmosphere Using Cassini ISS Narrow Angle Camera Pictures from the CURE/Cassini Imaging Project
NASA Astrophysics Data System (ADS)
Shitanishi, Jennifer; Gillam, S. D.
The study of Titan's atmosphere, which bears resemblance to early Earth's, may help us understand more of our own. Constructing a Monte Carlo model of Titan's atmosphere is helpful to achieve this goal. Methane (MT) and continuum band (CB) images of Titan taken by the CURE/Cassini Imaging Project, using the Cassini Narrow Angle Camera (NAC) were analyzed. They were scheduled by Cassini Optical Navigation. Images were obtained at phase 53░, 112░, 161░, and 165░. They include 22 total MT1(center wavelength at 619nm), MT2(727nm), MT3(889nm), CB1(635nm), CB2(751nm), and CB3(938nm) images. They were reduced with previously written scripts using the National Optical Astronomy Observatory Image Reduction and Analysis Facility scientific analysis suite. Correction for horizontal and vertical banding and cosmic ray hits were made. The MT images were registered with corresponding CB images to ensure that subsequently measured fluxes ratios came from the same parts of the atmosphere. Preliminary DN limb-to-limb scans and loci of the haze layers will be presented. Accurate estimates of the sub-spacecraft points on each picture will be presented. Flux ratios (FMT/FCB=Q0) along the scans and total absorption coefficients along the lines of sight from the spacecraft through the pixels (and into Titan) will also be presented.
High-frequency response and the possibilities of frequency-tunable narrow-band terahertz amplification in resonant tunneling nanostructures
Kapaev, V. V., E-mail: email@example.com; Kopaev, Yu. V.; Savinov, S. A.; Murzin, V. N. [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation)] [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation)
The characteristics of the high-frequency response of single- and double-well resonant tunneling structures in a dc electric field are investigated on the basis of the numerical solution of a time-dependent Schroedinger equation with open boundary conditions. The frequency dependence of the real part of high frequency conductivity (high-frequency response) in In{sub 0.53}Ga{sub 0.47}As/AlAs/InP structures is analyzed in detail for various values of the dc voltage V{sub dc} in the negative differential resistance (NDR) region. It is shown that double-well three-barrier structures are promising for the design of terahertz-band oscillators. The presence of two resonant states with close energies in such structures leads to a resonant (in frequency) response whose frequency is determined by the energy difference between these levels and can be controlled by varying the parameters of the structure. It is shown that, in principle, such structures admit narrow-band amplification, tuning of the amplification frequency, and a fine control of the amplification (oscillation) frequency in a wide range of terahertz frequencies by varying a dc electric voltage applied to the structure. Starting from a certain width of the central intermediate barrier in double-well structures, one can observe a collapse of resonances, where the structure behaves like a single-well system. This phenomenon imposes a lower limit on the oscillation frequency in three-barrier resonant tunneling structures.
High resolution spectroscopy of the 11.3 micron emission band
NASA Technical Reports Server (NTRS)
Achtermann, Jeff M.; Lacy, J. H.; Bruce, D. E.
High resolution spectra of the 11.3 micron emission band in M82 and NGC 7027 were obtained using the University of Texas IR echelle spectrometer on the IRTF in April 1988. The spectral resolution was 0.004 micron, with coverage from 11.0 to 11.6 microns. Spectra were measured at ten positions along a 10 min. long slit. Analysis of the data is still in progress, but initial results show no clear evidence of narrow structure within the feature. The analysis will involve comparison of the observed spectra to laboratory and predicted spectra of Polycylic Aromatic Hydrocarbons (PAHs) and Quenched Carbonaceous Composite (QCCs) to determine which may be responsible for the emission. The spectra will be examined with a goal of determining whether the emission is caused by molecular or solid state material. The data are also examined for evidence of variations in the shape and strength of the 11.3 micron feature with position on the sky. In NGC 7027 the 10 min. long slit went across the edge of the ionized nebulae, allowing comparison of emission from both ionized and neutral regions.
Are PAH molecules the carriers of Unidentified Infrared Emission bands?
NASA Astrophysics Data System (ADS)
Kwok, Sun; Zhang, Yong
Polycyclic aromatic hydrocarbon (PAH) molecules are widely considered as the preferred candidate for the carrier of the unidentified infrared emission bands observed in the interstellar medium and circumstellar envelopes. In this paper we report the result of fitting a variety of non-PAH spectra (silicates, hydrogenated amorphous carbon, coal and even artificial spectra) using the theoretical infrared spectra of PAHs from the NASA Ames PAH IR Spectroscopic Database. We show that these non-PAH spectra can be well fitted by PAH mixtures. This suggest that a general match between astronomical spectra and those of PAH mixtures does not necessarily provide definitive support for the PAH hypothesis.
Progenitor constraints on the Type-Ia supernova SN2011fe from pre-explosion Hubble Space Telescope He II narrow-band observations
NASA Astrophysics Data System (ADS)
Graur, Or; Maoz, Dan; Shara, Michael M.
We present Hubble Space Telescope (HST) imaging observations of the site of the Type-Ia supernova SN2011fe in the nearby galaxy M101, obtained about 1 yr prior to the event, in a narrow band centred on the He II ?4686 ┼ emission line. In a `single-degenerate' progenitor scenario, the hard photon flux from an accreting white dwarf (WD), burning hydrogen on its surface over ś1 Myr should, in principle, create a He III Str÷mgren sphere or shell surrounding the WD. Depending on the WD luminosity, the interstellar density, and the velocity of an outflow from the WD, the He III region could appear unresolved, extended, or as a ring, with a range of possible surface brightnesses. We find no trace of He II ?4686 ┼ line emission in the HST data. Using simulations, we set 2? upper limits on the He II ?4686 ┼ luminosity of LHe II < 3.4 ū 1034 erg s-1 for a point source, corresponding to an emission region of radius r < 1.8 pc. The upper limit for an extended source is LHe II < 1.7 ū 1035 erg s-1, corresponding to an extended region with r ś 11 pc. The largest detectable shell, given an interstellar-medium density of 1 cm-3, has a radius of ś6 pc. Our results argue against the presence, within the ś105 yr prior to the explosion, of a supersoft X-ray source of luminosity Lbol ? 3 ū 1037 erg s-1, or of a super-Eddington accreting WD that produces an outflowing wind capable of producing cavities with radii of 2-6 pc.
Optical spectroscopy of IRAS sources with infrared emission bands - IRAS 21282+5050 and the diffuse interstellar bands
NASA Technical Reports Server (NTRS)
Cohen, Martin; Jones, B. F.
Spectroscopy of the starlike optical counterpart to IRAS 21282+5050, a source with the 'hydrocarbon' IR emission band spectrum, shows an O7(f)-(WC 11) planetary nebula nucleus suffering an extinction of 5.7 mag. Emission-line widths in the WC spectrum are only about 100 km/s, indicating a very slow stellar wind. Optical diffuse interstellar bands (DIBs) are prominent, and five DIBs are strongly enhanced. The presence of circumstellar hydrocarbon molecules may explain both the IR emission bands and the enhanced DIBs.
Optical spectroscopy of IRAS sources with infrared emission bands. 1: IRAS 21282+5050 and the diffuse interstellar bands
NASA Technical Reports Server (NTRS)
Cohen, Martin; Jones, B. F.
Spectroscopy of the starlike optical counterpart to IRAS 21282+5050, a source with the hydrocarbon infrared emission band spectrum, shows an 07(f)-(WC11) planetary nebula nucleus suffering an extinction of 5.7 mag. Emission line widths in the WC spectrum are only approx. 100 km/s, indicating a very slow stellar wind. Optical diffuse interstellar bands (DIBs) are prominent. Five DIBs are strongly enhanced, namely lamda lamda 5797, 6196, 6203, 6283, and 6613. The presence of circumstellar hydrocarbon molecules may explain both the infrared emission bands and the enhanced DIBs.
Investigation of mechanisms of multimode emission from double-heterostructure AlGaAs injection lasers with narrow stripe contacts
Yu L Bessonov; S. S. Kurlenkov; V. N. Morozov; S. M. Sapozhnikov; Chan M Thai; V. R. Shidlovskii
An investigation was made of the spectral characteristics of planar stripe (contact width 6¢8 ?) lasers made of AlGaAs heterostructures. The steady-state emission spectrum could be of multimode type because of the high level of spontaneous emission in the lasing mode. The spectrum then became narrower on increase in the power and in the limit changed to the single-mode form.
Narrow-band red-emitting Sr[LiAl3N4]:Eu2+ as a next-generation LED-phosphor material
NASA Astrophysics Data System (ADS)
Pust, Philipp; Weiler, Volker; Hecht, Cora; T³cks, Andreas; Wochnik, Angela S.; Hen▀, Ann-Kathrin; Wiechert, Detlef; Scheu, Christina; Schmidt, Peter J.; Schnick, Wolfgang
To facilitate the next generation of high-power white-light-emitting diodes (white LEDs), the discovery of more efficient red-emitting phosphor materials is essential. In this regard, the hardly explored compound class of nitridoaluminates affords a new material with superior luminescence properties. Doped with Eu2+, Sr[LiAl3N4] emerged as a new high-performance narrow-band red-emitting phosphor material, which can efficiently be excited by GaN-based blue LEDs. Owing to the highly efficient red emission at ?max ~ 650 nm with a full-width at half-maximum of ~1,180 cm-1 (~50 nm) that shows only very low thermal quenching (>95% relative to the quantum efficiency at 200 ░C), a prototype phosphor-converted LED (pc-LED), employing Sr[LiAl3N4]:Eu2+ as the red-emitting component, already shows an increase of 14% in luminous efficacy compared with a commercially available high colour rendering index (CRI) LED, together with an excellent colour rendition (Ra8 = 91, R9 = 57). Therefore, we predict great potential for industrial applications in high-power white pc-LEDs.
Narrow-band red-emitting Sr[LiAl?N?]:Eu▓? as a next-generation LED-phosphor material.
Pust, Philipp; Weiler, Volker; Hecht, Cora; T³cks, Andreas; Wochnik, Angela S; Hen▀, Ann-Kathrin; Wiechert, Detlef; Scheu, Christina; Schmidt, Peter J; Schnick, Wolfgang
To facilitate the next generation of high-power white-light-emitting diodes (white LEDs), the discovery of more efficient red-emitting phosphor materials is essential. In this regard, the hardly explored compound class of nitridoaluminates affords a new material with superior luminescence properties. Doped with Eu(2+), Sr[LiAl3N4] emerged as a new high-performance narrow-band red-emitting phosphor material, which can efficiently be excited by GaN-based blue LEDs. Owing to the highly efficient red emission at ?(max) ~ 650 nm with a full-width at half-maximum of ~1,180 cm(-1) (~50 nm) that shows only very low thermal quenching (>95% relative to the quantum efficiency at 200 ░C), a prototype phosphor-converted LED (pc-LED), employing Sr[LiAl3N4]:Eu(2+) as the red-emitting component, already shows an increase of 14% in luminous efficacy compared with a commercially available high colour rendering index (CRI) LED, together with an excellent colour rendition (R(a)8 = 91, R9 = 57). Therefore, we predict great potential for industrial applications in high-power white pc-LEDs. PMID:24952748
The Irkutsk Barium filter for narrow-band wide-field high-resolution solar images at the Dutch Open Telescope
Rutten, Rob
1 The Irkutsk Barium filter for narrow-band wide-field high-resolution solar images at the Dutch ABSTRACT A wide-field birefringent filter for the barium II line at 455.4nm is developed in Irkutsk. The Barium line is excellent for Doppler-shift measurements because of low thermal line-broadening and steep
Assessment of Gastric Phenotypes Using Magnifying Narrow-Band Imaging for Differentiation of Gastric Carcinomas from Adenomas
Hashimoto, Satoru; Nishikura, Ken; Mizuno, Ken-Ichi; Takeuchi, Manabu; Ajioka, Yoichi
Background. Conventional white-light endoscopy and forceps biopsy are insufficient for definitive diagnosis of gastric adenoma. Immunohistochemical studies have reported an obvious phenotypic difference between adenomas and carcinomas. We investigated the utility of narrow-band imaging with magnifying endoscopy (NBI-ME) for mucin phenotypic assessment to differentiate carcinomas from adenomas. Methods. NBI-ME findings were classified into A, B, and AB types, which revealed papillary, tubular pits and groove microstructures, respectively. To investigate A-B classifications retrospectively, 137 patients (155 lesions) that were diagnosed pretherapeutically with adenoma or borderline lesions by biopsy were enrolled. The mucin phenotype was analyzed immunohistochemically in the first 60 lesions. Results. After endoscopic submucosal dissection, A type and AB type lesions were determined histologically as carcinoma (81/82, 99%). B type lesions were adenoma (29/73, 40%) and carcinoma (44/73, 60%). A or AB type correlated to histological carcinomas (sensitivity 65%, specificity 97%, and accuracy 71%). Mucin phenotypes were gastric or gastrointestinal in A type and AB type carcinomas (31/37, 84%) and intestinal in B type adenomas and carcinomas (21/23, 91%). Conclusions. NBI-ME has the advantage of the assessment of mucin phenotypes in gastric carcinomas and adenomas. The proposed A-B classification is useful, especially for differentiation of gastric or gastrointestinal carcinomas from adenomas. PMID:25371671
New high Tc multiferroics KBiFe2O5 with narrow band gap and promising photovoltaic effect
Zhang, Ganghua; Wu, Hui; Li, Guobao; Huang, Qingzhen; Yang, Chongyin; Huang, Fuqiang; Liao, Fuhui; Lin, Jianhua
Intrinsic polarization of ferroelectrics (FE) helps separate photon-generated charge carriers thus enhances photovoltaic effects. However, traditional FE with transition-metal cations (M) of d0 electron in MO6 network typically has a band gap (Eg) exceeding 3.0?eV. Although a smaller Eg (2.6?eV) can be obtained in multiferroic BiFeO3, the value is still too high for optimal solar energy applications. Computational ōmaterials genomeö searches have predicted several exotic MO6 FE with Eg < 2.0?eV, all thus far unconfirmed because of synthesis difficulties. Here we report a new FE compound with MO4 tetrahedral network, KBiFe2O5, which features narrow Eg (1.6?eV), high Curie temperature (Tc ~ 780?K) and robust magnetic and photoelectric activities. The high photovoltage (8.8?V) and photocurrent density (15??A/cm2) were obtained, which is comparable to the reported BiFeO3. This finding may open a new avenue to discovering and designing optimal FE compounds for solar energy applications. PMID:23405279
Toward Photochemical Water Splitting Using Band-Gap-Narrowed Semiconductors and Transition-Metal Based Molecular Catalysts
Muckerman,J.T.; Rodriguez, J.A.; Fujita, E.
We are carrying out coordinated theoretical and experimental studies of toward photochemical water splitting using band-gap-narrowed semiconductors (BGNSCs) with attached multi-electron molecular water oxidation and hydrogen production catalysts. We focus on the coupling between the materials properties and the H{sub 2}O redox chemistry, with an emphasis on attaining a fundamental understanding of the individual elementary steps in the following four processes: (1) Light-harvesting and charge-separation of stable oxide or oxide-derived semiconductors for solar-driven water splitting, including the discovery and characterization of the behavior of such materials at the aqueous interface; (2) The catalysis of the four-electron water oxidation by dinuclear hydroxo transition-metal complexes with quinonoid ligands, and the rational search for improved catalysts; (3) Transfer of the design principles learned from the elucidation of the DuBois-type hydrogenase model catalysts in acetonitrile to the rational design of two-electron hydrogen production catalysts for aqueous solution; (4) Combining these three elements to examine the function of oxidation catalysts on BGNSC photoanode surfaces and hydrogen production catalysts on cathode surfaces at the aqueous interface to understand the challenges to the efficient coupling of the materials functions.
Improved optical identification of laterally spreading type "0-IIb" gastric lesion with narrow band imaging magnification endoscopy.
Eleftheriadis, Nikolas; Inoue, Haruhiro; Ikeda, Haruo; Maselli, Roberta; Onimaru, Manabu; Yoshida, Akira; Ito, Hiroaki; Hamatani, Shigeharu; Kudo, Shin-Ei
Endoscopic submucosal dissection (ESD) has become the treatment of choice for early gastric cancer. Accurate identification of tumor borders is crucial for curative ESD. Narrow band imaging magnification endoscopy (NBI-ME) has been effectively used for assessment of superficial gastric lesions; however, international experience in type "0-IIb" gastric lesions is limited. Successful endoscopic tissue characterization of laterally spreading type "0-IIb" early gastric cancer in a 74-year-old male with known type "0-IIa" lesion, using zoom NBI-ME, is reported. While the type "0-IIa" gastric lesion was clearly recognized by white light endoscopy and indigo carmine chromoendoscopy, the laterally spreading type "0-IIb" gastric cancer was only identified on the basis of NBI-ME malignant microvascular and mucosal microsurface pattern. Based on NBI-ME findings, accurate border marking approximately 1 mm apart from the demarcation line and complete en bloc ESD resection of both tumors was successfully succeeded. Recovery was uneventful. Histopathology showed moderately differentiated gastric adenocarcinoma in type "0-IIa" lesion and a small area of low-grade well-differentiated gastric adenocarcinoma in type "0-IIb" lesion. Conclusively, improved real-time optical identification of laterally spreading type "0-IIb" gastric lesion was achieved with NBI-ME. PMID:24975679
Phasing segmented mirrors: a modification of the Keck narrow-band technique and its application to extremely large telescopes.
Schumacher, Achim; Devaney, Nicholas; Montoya, Luzma
Future telescopes with diameters greater than 10 m, usually referred to as extremely large telescopes (ELTs), will employ segmented mirrors made up of hundreds or even thousands of segments, with tight constraints on the piston errors between individual segments. The 10-m Keck telescopes are routinely phased with the narrow-band phasing technique. This is a variation of the Shack-Hartmann wave-front sensor in which the signal is the correlation between individual subimages and simulated images. We have investigated the applicability of this technique to ELTs, and in the process we have developed what to our knowledge is a new algorithm in which each subimage provides on its own a piston-dependent value. We also discuss an alternative algorithm to resolve the lambda ambiguity that allows detection of problematic cases, and a modification of the singular-value-decomposition procedure used to phase the whole mirror, using weightings on individual measurement errors. By means of simulations we show that the modified technique shows improved performance and that it can work with sufficient precision on telescopes as large as 100 m. PMID:11900007
The Role of Narrow Band Imaging in the Detection of Recurrent Laryngeal and Hypopharyngeal Cancer after Curative Radiotherapy
Zabrodsky, Michal; Plzak, Jan
Narrow band imaging is considered a significant improvement in the possibility of detecting early mucosal lesion of the upper aerodigestive tract. Early detection of mucosal neoplastic lesions is of utmost importance for patients survival. There is evidence that, especially in patients previously treated by means of curative radiotherapy or chemoradiotherapy, the early detection rate of recurrent disease is quite low. The aim of this study was to prove whether the videoendoscopy coupled with NBI might help detect recurrent or secondary tumors of the upper aerodigestive tract. 66 patients previously treated by means of RT or CRT with curative intent were enrolled in the study. All patients underwent transnasal flexible videoendoscopy with NBI mode under local anesthesia. When a suspicious lesion was identified in an ambulatory setting, its nature was proved histologically. Many of these changes were not identifiable by means of conventional white light (WL) endoscopy. The accuracy, sensitivity, specificity, and positive and negative predictive value of the method are very high (88%, 92%, 76%, 96%, and 91%, resp.). Results demonstrate that outpatient transnasal endoscopy with NBI is an excellent method for the follow-up of patients with carcinomas of the larynx and the hypopharynx primarily treated with radiotherapy. PMID:25101264
Banks of templates for all-sky narrow-band searches of gravitational waves from spinning neutron stars
Andrzej Pisarski; Piotr Jaranowski
We construct efficient banks of templates suitable for all-sky narrow-band searches of almost monochromatic gravitational waves originating from spinning neutron stars in our Galaxy in data collected by interferometric detectors. We thus assume that both the position of the gravitational-wave source in the sky and the wave's frequency together with spindown parameters are unknown. In the construction we employ simplified model of the signal with constant amplitude and phase which is a linear function of unknown parameters. All our template banks enable usage of the fast Fourier transform algorithm in the computation of the maximum-likelihood $\\mathcal{F}$-statistic for nodes of the grids defining the bank and fulfill an additional constraint needed to resample the data to barycentric time efficiently. Our template banks are suitable for larger range of search parameters than the banks previously proposed and compared to them they have smaller thicknesses for certain values of search parameters. One of our template banks has thickness 12\\% smaller than the thickness of the template bank used in the recent all-sky $\\mathcal{F}$-statistic-based search for continuous gravitational waves in Virgo VSR1 data.
New high T(c) multiferroics KBiFe?O? with narrow band gap and promising photovoltaic effect.
Zhang, Ganghua; Wu, Hui; Li, Guobao; Huang, Qingzhen; Yang, Chongyin; Huang, Fuqiang; Liao, Fuhui; Lin, Jianhua
Intrinsic polarization of ferroelectrics (FE) helps separate photon-generated charge carriers thus enhances photovoltaic effects. However, traditional FE with transition-metal cations (M) of d? electron in MO? network typically has a band gap (E(g)) exceeding 3.0?eV. Although a smaller E(g) (2.6?eV) can be obtained in multiferroic BiFeO?, the value is still too high for optimal solar energy applications. Computational "materials genome" searches have predicted several exotic MO? FE with E(g) < 2.0?eV, all thus far unconfirmed because of synthesis difficulties. Here we report a new FE compound with MO? tetrahedral network, KBiFe?O?, which features narrow E(g) (1.6?eV), high Curie temperature (T(c) ~ 780?K) and robust magnetic and photoelectric activities. The high photovoltage (8.8?V) and photocurrent density (15??A/cm▓) were obtained, which is comparable to the reported BiFeO?. This finding may open a new avenue to discovering and designing optimal FE compounds for solar energy applications. PMID:23405279
Gene profiling of narrow-band UVB-induced skin injury defines cellular and molecular innate immune responses
Crispin, MilĶne Kennedy; Fuentes-Duculan, Judilyn; Gulati, Nicholas; Johnson-Huang, Leanne M.; Lentini, Tim; Sullivan-Whalen, Mary; Gilleaudeau, Patricia; Cueto, Inna; Sußrez-Fari±as, Mayte; Lowes, Michelle A.; Krueger, James G.
The acute response of human skin to ultraviolet B (UVB) radiation has not been fully characterized. We sought to define the cutaneous response at 24 hours following narrow-band UVB (NB-UVB, 312 nm peak), a therapeutically relevant source of UVB, using transcriptional profiling, immunohistochemistry, and immunofluorescence. There were 1,522 unique differentially-regulated genes, including upregulation of antimicrobial peptides (AMPs) (S100A7, S100A12, human beta-defensin 2, and elafin), neutrophil and monocyte/dendritic cell (DC) chemoattractants (IL-8, CXCL1, CCL20, CCL2). Ingenuity Pathway Analysis demonstrated activation of innate defense and early adaptive immune pathways. Immunohistochemistry confirmed increased epidermal staining for AMPs (S100A7, S100A12, human beta-defensin 2, and elafin). Inflammatory myeloid CD11c+BDCA1? DCs were increased in irradiated skin, which were immature as shown by minimal co-localization with DC-LAMP, and co-expressed inflammatory markers TNF and TRAIL in irradiated skin. There were increased BDCA3+ DCs, a cross-presenting DC subtype with immunosuppressive functions, and these cells have not been previously characterized as part of the response to UVB. These results show that the acute response of human skin to erythemogenic doses of NB-UVB includes activation of innate defense mechanisms, as well as early infiltration of multiple subtypes of inflammatory DCs, which could serve as a link between innate and adaptive immunity. PMID:23151847
Principal resonance responses of SDOF systems with small fractional derivative damping under narrow-band random parametric excitation
NASA Astrophysics Data System (ADS)
Liu, Di; Li, Jing; Xu, Yong
The principal resonance responses of nonlinear single-degree-of-freedom (SDOF) systems with lightly fractional derivative damping of order ? (0 < ? < 1) subject to the narrow-band random parametric excitation are investigated. The method of multiple scales is developed to derive two first order stochastic differential equation of amplitude and phase, and then to examine the influences of fractional order and intensity of random excitation on the first-order and second-order moment. As an example, the stochastic Duffing oscillator with fractional derivative damping is considered. The effects of detuning frequency parameter, the intensity of random excitation and the fractional order derivative damping on stability are studied through the largest Lyapunov exponent. The corresponding theoretical results are well verified through direct numerical simulations. In addition, the phenomenon of stochastic jump is analyzed for parametric principal resonance responses via finite differential method. The stochastic jump phenomena indicates that the most probable motion is around the larger non-trivial branch of the amplitude response when the intensity of excitation is very small, and the probable motion of amplitude responses will move from the larger non-trivial branch to trivial branch with the increasing of the intensity of excitation. Such stochastic jump can be considered as bifurcation.
Narrow Band Imaging with Magnification Endoscopy for Celiac Disease: Results from a Prospective, Single-Center Study
De Luca, L.; Ricciardiello, L.; Rocchi, M. B. L.; Fabi, M. T.; Bianchi, M. L.; de Leone, A.; Fiori, S.; Baroncini, D.
In celiac disease (CD), the intestinal lesions can be patchy and partial villous atrophy may elude detection at standard endoscopy (SE). Narrow Band Imaging (NBI) system in combination with a magnifying endoscope (ME) is a simple tool able to obtain targeted biopsy specimens. The aim of the study was to assess the correlation between NBI-ME and histology in CD diagnosis and to compare diagnostic accuracy between NBI-ME and SE in detecting villous abnormalities in CD. Forty-four consecutive patients with suspected CD undergoing upper gastrointestinal endoscopy have been prospectively evaluated. Utilizing both SE and NBI-ME, observed surface patterns were compared with histological results obtained from biopsy specimens using the k-Cohen agreement coefficient. NBI-ME identified partial villous atrophy in 12 patients in whom SE was normal, with sensitivity, specificity, and accuracy of 100%, 92.6%, and 95%, respectively. The overall agreement between NBI-ME and histology was significantly higher when compared with SE and histology (kappa score: 0.90 versus 0.46; P = 0.001) in diagnosing CD. NBI-ME could help identify partial mucosal atrophy in the routine endoscopic practice, potentially reducing the need for blind biopsies. NBI-ME was superior to SE and can reliably predict in vivo the villous changes of CD. PMID:23983448
Data analysis of gravitational-wave signals from spinning neutron stars. V. A narrow-band all-sky search
Astone, Pia [Istituto Nazionale di Fisica Nucleare, (INFN)-Rome I, 00185 Rome (Italy); Borkowski, Kazimierz M. [Centre for Astronomy, Nicolaus Copernicus University, Gagarina 11, 87-100 Torun (Poland); Jaranowski, Piotr; Pietka, Maciej [Faculty of Physics, University of Bialystok, Lipowa 41, 15-424 Bialystok (Poland); Krolak, Andrzej [Institute of Mathematics, Polish Academy of Sciences, Sniadeckich 8, 00-950 Warsaw (Poland)
We present theory and algorithms to perform an all-sky coherent search for periodic signals of gravitational waves in narrow-band data of a detector. Our search is based on a statistic, commonly called the F-statistic, derived from the maximum-likelihood principle in Paper I of this series. We briefly review the response of a ground-based detector to the gravitational-wave signal from a rotating neuron star and the derivation of the F-statistic. We present several algorithms to calculate efficiently this statistic. In particular our algorithms are such that one can take advantage of the speed of fast Fourier transform in calculation of the F-statistic. We construct a grid in the parameter space such that the nodes of the grid coincide with the Fourier frequencies. We present interpolation methods that approximately convert the two integrals in the F-statistic into Fourier transforms so that the fast Fourier transform algorithm can be applied in their evaluation. We have implemented our methods and algorithms into computer codes and we present results of the Monte Carlo simulations performed to test these codes.
Comparison of the Efficacy of Methotrexate and Narrow-Band Ultraviolet B for the Treatment of Plaque-Type Psoriasis.
Solak, Berna; Dikicier, Bahar Sevimli; Yaldz, Mahizer; Erkorkmaz, Unal; Erdem, Teoman
Although many treatment methods for psoriasis are available, it is still a challenging task for the dermatologist to choose the optimal one. To the best of our knowledge, there was only 1 small study of head-to-head comparison of the efficacy of these medications to date. In this retrospective study, we compared the clinical efficacy and recurrence rates of narrow-band ultraviolet B (NB-UVB) and methotrexate (MTX) treatments for plaque-type psoriasis. Sixty-seven patients with psoriasis who received NB-UVB (n = 35) or MTX (n = 32) treatments were included in the study. Response was assessed by Psoriasis Area and Severity Index (PASI) at baseline, 4th and 12th week. Our results revealed that both treatment modalities significantly reduced the PASI score compared with baseline (P < 0.001 and P < 0.001, respectively). Moreover, there was no significant difference between both regimens regardless of baseline PASI scores (P = 0.796 at 4th week and P = 0.606 at 12th week). Recurrence rates in both treatments were also similar at 3 months (42.9% for NB-UVB and 65.2% for MTX, P = 0.162). In conclusion, the use of NB-UVB can be considered as a preliminary treatment method rather than MTX when taking into account of the lower side effect profile even in patients with severe psoriasis. PMID:25470611
Clinical impact of narrow-band imaging magnifying endoscopy for 'basal layer type squamous cell carcinoma' in the esophagus.
Goda, Kenichi; Tajiri, Hisao; Ikegami, Masahiro; Dobashi, Akira; Yoshimura, Noboru
A 61-year-old man had received endoscopic submucosal dissection (ESD) for early gastric cancer twice. Then he had undergone annual control esophagogastroduodenoscopy using narrow-band imaging (NBI) magnifying endoscope. At the esophagogastroduodenoscopy, we were not able to detect any significant finding in the esophagus by conventional endoscopy. Switching to NBI mode, a brownish area was showed in the middle esophagus. The lesion showing the brownish area was predicted to be mucosal squamous cell carcinoma (SCC) as a result of assessment of morphologic change of intraepithelial papillary capillary loop under magnifying NBI observation. Lugol chromoendoscopy displayed the lesion as unstained area corresponding to the brownish area visualized by NBI. The ESD was performed for the lesion. Histology from ESD specimen showed SCC with minimal invasion to lamina propria at multifocal sites. The SCC was surrounded by low-grade intraepithelial neoplasia. Most of the SCC showed a high degree of cytological and architectural atypia confined to the lower half of the epithelium. The type of SCC was called as 'basal layer type SCC' mainly by Japanese pathologists. We suggest that magnifying NBI endoscopy can be useful for detecting and diagnosing 'basal layer type SCC'. PMID:21535206
Improved optical identification of laterally spreading type ō0-IIbö gastric lesion with narrow band imaging magnification endoscopy
Eleftheriadis, Nikolas; Inoue, Haruhiro; Ikeda, Haruo; Maselli, Roberta; Onimaru, Manabu; Yoshida, Akira; Ito, Hiroaki; Hamatani, Shigeharu; Kudo, Shin-ei
Endoscopic submucosal dissection (ESD) has become the treatment of choice for early gastric cancer. Accurate identification of tumor borders is crucial for curative ESD. Narrow band imaging magnification endoscopy (NBI-ME) has been effectively used for assessment of superficial gastric lesions; however, international experience in type ō0-IIbö gastric lesions is limited. Successful endoscopic tissue characterization of laterally spreading type ō0-IIbö early gastric cancer in a 74-year-old male with known type ō0-IIaö lesion, using zoom NBI-ME, is reported. While the type ō0-IIaö gastric lesion was clearly recognized by white light endoscopy and indigo carmine chromoendoscopy, the laterally spreading type ō0-IIbö gastric cancer was only identified on the basis of NBI-ME malignant microvascular and mucosal microsurface pattern. Based on NBI-ME findings, accurate border marking approximately 1 mm apart from the demarcation line and complete en bloc ESD resection of both tumors was successfully succeeded. Recovery was uneventful. Histopathology showed moderately differentiated gastric adenocarcinoma in type ō0-IIaö lesion and a small area of low-grade well-differentiated gastric adenocarcinoma in type ō0-IIbö lesion. Conclusively, improved real-time optical identification of laterally spreading type ō0-IIbö gastric lesion was achieved with NBI-ME. PMID:24975679
Observer Variability in Gastric Neoplasm Assessment Using the Vessel Plus Surface Classification for Magnifying Endoscopy with Narrow Band Imaging
Yoo, Chan Hui; Park, Seun Ja; Moon, Won; Kim, Hyung Hun; Song, Jun Young; Kim, Do Hyun
Background/Aims Recent studies have demonstrated that magnifying endoscopy with narrow band imaging (ME-NBI) facilitates differentiation of early gastric cancer from gastric adenoma using vessel plus surface (VS) classification. This study estimated the interobserver and intraobserver agreement of endoscopists using the Yao VS classification system for the gastric mucosal surface. Methods We retrospectively reviewed patients who underwent endoscopic submucosal dissection or endoscopic mucosal resection, and selected cases in which preoperative ME-NBI was conducted. Before testing endoscopists, a 20-minute training module was given. Static ME-NBI images (n=47 cases) were presented to seven endoscopists (two experts and five trainees) who were asked to assess the images in 20 seconds using the Yao VS classification system. After 2 weeks, the endoscopists were asked to analyze the images again. The ? statistic was calculated for intraobserver and interobserver variability. Results The mean ? for intraobserver agreement was 0.69 (experts, 0.74; trainees, 0.64). The mean ? for interobserver agreement was 0.42 (experts, 0.49; trainees, 0.40). Conclusions We obtained reliable results as assessed by observer variability, with only brief training on VS classification. The VS classification appears to provide an objective assessment of ME-NBI for trainees who are not familiar with ME-NBI. PMID:24570886
Narrow band imaging with magnification endoscopy for celiac disease: results from a prospective, single-center study.
De Luca, L; Ricciardiello, L; Rocchi, M B L; Fabi, M T; Bianchi, M L; de Leone, A; Fiori, S; Baroncini, D
In celiac disease (CD), the intestinal lesions can be patchy and partial villous atrophy may elude detection at standard endoscopy (SE). Narrow Band Imaging (NBI) system in combination with a magnifying endoscope (ME) is a simple tool able to obtain targeted biopsy specimens. The aim of the study was to assess the correlation between NBI-ME and histology in CD diagnosis and to compare diagnostic accuracy between NBI-ME and SE in detecting villous abnormalities in CD. Forty-four consecutive patients with suspected CD undergoing upper gastrointestinal endoscopy have been prospectively evaluated. Utilizing both SE and NBI-ME, observed surface patterns were compared with histological results obtained from biopsy specimens using the k-Cohen agreement coefficient. NBI-ME identified partial villous atrophy in 12 patients in whom SE was normal, with sensitivity, specificity, and accuracy of 100%, 92.6%, and 95%, respectively. The overall agreement between NBI-ME and histology was significantly higher when compared with SE and histology (kappa score: 0.90 versus 0.46; P = 0.001) in diagnosing CD. NBI-ME could help identify partial mucosal atrophy in the routine endoscopic practice, potentially reducing the need for blind biopsies. NBI-ME was superior to SE and can reliably predict in vivo the villous changes of CD. PMID:23983448
High-resolution spectra of distant compact narrow emission line galaxies: Progrenitors of spheroidal galaxies
NASA Technical Reports Server (NTRS)
Koo, David C.; Guzman, Rafael; Faber, S. M.; Illingworth, Garth D.; Bershady, Matthew A.; Kron, Richard G.; Takamiya, Marianne
Emission-line velocity widths have been determined for 17 faint (B approximately 20-23) very blue, compact galaxies whose redshifts range from z = 0.095 to 0.66. The spectra have a resolution of 8 Km/s and were taken with the HIRES echelle spectrograph of the Keck 10 m telescope. The galaxies are luminous with all but two within 1 mag of M(sub B) approximately -21. Yet they exhibit narrow velocity widths between sigma = 28-157 km/s, more consistent with typical values of extreme star-forming galaxies than with those of nearby spiral galaxies of similar luminosity. In particular, objects with sigma is less than or equal to 65 km/s follow the same correlations between sigma and both blue and H beta luminosities as those of nearby H II galaxies. These results strengthen the identification of H II glaxies as thier local counterparts. The blue colors and strong emission lines suggest these compact galaxies are undergoing a recent, strong burst of star formation. Like those which characterize some H II galaxies, this burst could be a nuclear star-forming event within a much larger, older stellar population. If the burst is instead a major episode in the total star-forming history, these distant galaxies could fade enough to match the low luminosities and surface brightnesses typical of nearby spheroidals like NGC 185 or NGC 205. Together with evidence for recent star formation, exponential light profiles, and subsolar metallicities, the postfading correlations between luminosity and velocity width and bewtween luminosity and surface brightness suggest that among the low-sigma galaxies, we may be witnessing, in situ, the progenitors of today's spheroidal galaxies.
The X-ray spectrum and time variability of narrow emission line galaxies
NASA Technical Reports Server (NTRS)
Mushotzky, R.
X-ray spectral and temporal observations are reported for six narrow emission line galaxies (NELGs), all of which are fitted by power-law X-ray spectra of energy slope 0.8 and have column densities in the line of sight greater than 1 x 10 to the 22nd atoms/sq cm. Three of the objects, NGC 526a, NGC 2110 and MCG-5-23-16 are variable in their X-ray flux, and the latter two, along with NGC 5506 and NGC 7582, showed detectable variability in at least one observation. The measured X-ray properties of these NELGs, which also included NGC 2992, strongly resemble those of previously-measured type 1 Seyferts of the same X-ray luminosity and lead to the conclusion of great similarity between the NELGs and low-luminosity type 1 Seyferts. The implications of these observations for the optical line-emitting region structure of these galaxies are discussed.
Identifying AGN Balmer absorptions and stratified narrow emission-line region kinematics in SDSS J112611.63+425246.4
NASA Astrophysics Data System (ADS)
Wang, J.; Xu, D. W.
Context. Balmer absorption is a rare phenomenon in active galactic nuclei (AGNs). So far, only seven Balmer-absorption AGNs have been reported in the literature. Aims: We here report the identification of SDSS J112611.63+425246 as a new Balmer-absorption AGN through our spectral analysis and study the kinematics of its narrow emission-line region (NLR). Methods: We modeled the continuum by a linear combination of a starlight component, a power law from the central AGN, and the emission from the FeII complex. After subtracting the modeled continuum, each emission or absorption line profile is a sum of multi-Gaussian functions. All the line shifts were determined with respect to the modeled starlight component. Results: By using the host starlight as a reference for the local system, both H? and H? show AGN absorptions with a blueshift of ~300 km s-1. We identify a strong anticorrelation between the inferred velocity shifts and the ionization potential for various narrow emission lines, which suggests a stratified NLR kinematics. A de-accelerated outflow is implied for the inner NLR gas, an accelerated inflow for the outer NLR gas. This complicated NLR kinematics additionally implies that AGN narrow emission lines, even for the low-ionized lines, might not be a reliable substitute for the velocity of the local system.
Design of narrow band-pass filters based on the resonant-tunneling phenomenon in multi-core photonic crystal fibers.
Saitoh, Kunimasa; Florous, Nikolaos J; Koshiba, Masanori; Skorobogatiy, Maksim
The objective of the present paper is to introduce and numerically demonstrate the operation of a novel band-pass filter based on the phenomenon of resonant tunneling inmulti-core photonic crystal fibers (PCFs). The proposed PCF consists of two identical cores separated by a third one which acts as a resonator. With a fine adjustment of the design parameters associated with the resonant-core, phase matching at a single wavelength can be achieved, thus enabling very narrow-band resonant directional coupling between the input and the output cores. The validation of the design is ensured with an accurate PCF analysis based on finite element and beam propagation algorithms. The proposed narrow band-pass filter can be employed in various applications such as all fiber and pass/bandstop filtering. PMID:19503248
Design of narrow band-pass filters based on the resonant-tunneling phenomenon in multi-core photonic crystal fibers
NASA Astrophysics Data System (ADS)
Saitoh, Kunimasa; Florous, Nikolaos J.; Koshiba, Masanori; Skorobogatiy, Maksim
The objective of the present paper is to introduce and numerically demonstrate the operation of a novel band-pass filter based on the phenomenon of resonant tunneling inmulti-core photonic crystal fibers (PCFs). The proposed PCF consists of two identical cores separated by a third one which acts as a resonator. With a fine adjustment of the design parameters associated with the resonant-core, phase matching at a single wavelength can be achieved, thus enabling very narrow-band resonant directional coupling between the input and the output cores. The validation of the design is ensured with an accurate PCF analysis based on finite element and beam propagation algorithms. The proposed narrow band-pass filter can be employed in various applications such as all fiber and pass/bandstop filtering.
Investigation of mechanisms of multimode emission from double-heterostructure AlGaAs injection lasers with narrow stripe contacts
Bessonov, Y.L.; Kurlenkov, S.S.; Morozov, V.N.; Sapozhnikov, S.M.; Thai, C.t.; Shidlovskii, V.R.
An investigation was made of the spectral characteristics of planar stripe (contact width 6--8 ..mu..) lasers made of AlGaAs heterostructures. The steady-state emission spectrum could be of multimode type because of the high level of spontaneous emission in the lasing mode. The spectrum then became narrower on increase in the power and in the limit changed to the single-mode form. However, in the presence of self-modulation processes the multimode nature of the emission spectrum could be explained by a theory of transient effects and in this case the width of the spectrum increased on increase in the power.
Generation condition of the Upper-band and Lower-band chorus emissions in the Earth's magnetosphere
NASA Astrophysics Data System (ADS)
Habagishi, T.; Yagitani, S.; Omura, Y.; Kojima, H.
In the present study, chorus emissions have been analyzed on the basis of the nonlinear growth theory [1] in the Earth's magnetosphere. A rising-tone chorus emission is initially generated continuously in the frequency range from 0.1 to 0.7 fce0, where fce0 is the gyrofrequency in the generation region. Because of the nonlinear damping mechanism [2] the rising-tone chorus is separated into upper and lower bands at half the local gyrofrequency for the quasi-parallel propagation toward higher latitude (i.e. toward larger gyrofrequencies). Thus the lower cutoff of the upper-band chorus indicates half-gyrofrequency at the observational point (1/2 fce), whereas the upper cutoff of the lower-band chorus indicates half the gyrofrequency in the generation region (1/2fce0). We found an observational evidence of such characteristics of upper-band and lower-band chorus observed by the wave form capture (WFC) and the sweep frequency analyzer (SFA) onboard Geotail [3]. Mainly ';'lower-band-only chorus'' (only the lower-band emission exists) is observed and occasionally ';'dual-band chorus'' (both the upper-band and the lower-band emissions) is observed by Geotail. In this study, we statistically analyze the difference between the lower-band-only chorus and the dual-band chorus, using the SFA data obtained during October, 1992 and August, 2011. It has been confirmed that the dual-band chorus is generated because of the nonlinear damping at half the local gyrofrequency during the propagation. When the dual-band chorus propagates toward higher latitudes with its the upper-band part completely damped at half the local gyrofrequencies, the dual-band chorus becomes the lower-band-only chorus. We assume that the upper cutoff frequency of the lower-band chorus equals to the half-gyrofrequency in the generation region. When 0.7 fce0 (i.e. upper limit frequency of the chorus generation) is higher than local 1/2 fce, the dual-band chorus is possibly observed because the higher-frequency part of the upper-band chorus would not be damped. When 0.7 fce0 is lower than local 1/2 fce, the lower-band-only chorus is observed because the upper-band chorus is completely damped. References [1] Omura Y., Y. Katoh and D. Summers (2008), Theory and simulation of the generation of whistler-mode chorus, J. Geophys. Res., 113, A04223, doi:10.1029/2007JA012622. [2] Omura Y., M. Hikishima, Y. Katoh, D.Summers, and S. Yagitani (2009), Nonlinear mechanisms of lower-band and upper-band VLF chorus emissions in the magnetosphere, J. Geophys. Res., 114, A07217, doi:10.1029/2009JA014206 [3] S. Yagitani, T. Habagishi, S. Mori, Y. Omura, and H. Kojima, Generation and propagation characteristics of dual-band chorus emissions observed by Geotail, American Geophysical Union Fall Meeting 2012, December 2012, San Francisco, USA.
Diagnostic Efficacy of Magnifying Endoscopy with Narrow-Band Imaging for Gastric Neoplasms: A Meta-Analysis
Lv, Xiuhe; Wang, Chunhui; Xie, Yan; Yan, Zhaoping
Background Magnifying endoscopy with narrow-band imaging (ME-NBI) is a novel, image-enhanced endoscopic technique for differentiating gastrointestinal neoplasms and potentially enabling pathological diagnosis. Objectives The aim of this analysis was to assess the diagnostic performance of ME-NBI for gastric neoplasms. Methods We performed a systematic search of the PubMed, EMbase, Web of Science, and Cochrane Library databases for relevant studies. Meta-DiSc (version 1.4) and STATA (version 11.0) software were used for the data analysis. Random effects models were used to assess diagnostic efficacy. Heterogeneity was tested by the Q statistic and I2 statistic. Meta-regression was used to analyze the sources of heterogeneity. Results A total of 10 studies, with 2151 lesions, were included. The pooled characteristics of these studies were as follows: sensitivity 0.85 (95% confidence interval [CI]: 0.81¢0.89), specificity 0.96 (95% confidence interval [CI]: 0.95¢0.97), and area under the curve (AUC) 0.9647. In the subgroup analysis, which compared the diagnostic efficacy of ME-NBI and white light imaging (WLI), the pooled sensitivity and specificity of ME-NBI were 0.87 (95% CI: 0.80¢0.92) and 0.93 (95% CI: 0.90¢0.95), respectively, and the area under the curve (AUC) was 0.9556. In contrast, the pooled sensitivity and specificity of WLI were 0.61 (95% CI: 0.53¢0.69) and 0.65 (95% CI: 0.60¢0.69), respectively, and the area under the curve (AUC) was 0.6772. Conclusions ME-NBI presents a high diagnostic value for gastric neoplasms and has a high specificity. PMID:25856544
Hybrid quantum dot-superconducting systems: Josephson current and Kondo effect in the narrow-band limit
NASA Astrophysics Data System (ADS)
Allub, R.; Proetto, C. R.
The case of a quantum dot connected to two superconducting leads is studied by using the narrow-band limit to describe the superconducting degrees of freedom. The model provides a simple theoretical framework, almost analytical, to analyze the interplay between the Kondo effect, superconductivity, and finite temperature. In the quantum dot Kondo regime, the model is completely characterized by the ratio ? /J , with ? the superconducting gap and J an effective antiferromagnetic exchange coupling between the dot and the leads. The model allows us to calculate, at any temperature T , the equilibrium Josephson current through the dot in a very straightforward way as a function of ? /J . The behavior of the current allows us to distinguish the four types of hybrid junctions: 0, 0',?', and ? . The presence of the 0- and 0'-junction configurations are intrinsically linked to the Kondo effect in the quantum dot, while the ? - and ?'-junction configurations are driven by the superconductivity in the leads. The Josephson critical current has a non-monotonic behavior with temperature, that may be used for the experimental characterization of the fundamental 0 -? transition. The model allows us to obtain easily a phase diagram ? /J vs temperature, from where we can obtain an overall picture on the stability of the different types of junctions. From the explicit analytical expressions for the ground-state, low-energy excitations, free energy, and Josephson current, it is easy to understand the physical nature of the main features of the critical current and the phase diagram. The results, obtained with a minimum of numerical effort, are in a good qualitative agreement with more demanding calculational approaches aimed to solve the full model.
Ground-based Pa? Narrow-band Imaging of Local Luminous Infrared Galaxies. I. Star Formation Rates and Surface Densities
NASA Astrophysics Data System (ADS)
Tateuchi, Ken; Konishi, Masahiro; Motohara, Kentaro; Takahashi, Hidenori; Mitani Kato, Natsuko; Kitagawa, Yutaro; Todo, Soya; Toshikawa, Koji; Sako, Shigeyuki; Uchimoto, Yuka K.; Ohsawa, Ryou; Asano, Kentaro; Ita, Yoshifusa; Kamizuka, Takafumi; Komugi, Shinya; Koshida, Shintaro; Manabe, Sho; Nakamura, Tomohiko; Nakashima, Asami; Okada, Kazushi; Takagi, Toshinobu; Tanabķ, Toshihiko; Uchiyama, Mizuho; Aoki, Tsutomu; Doi, Mamoru; Handa, Toshihiro; Kawara, Kimiaki; Kohno, Kotaro; Minezaki, Takeo; Miyata, Takashi; Morokuma, Tomoki; Soyano, Takeo; Tamura, Yoichi; Tanaka, Masuo; Tarusawa, Ken'ichi; Yoshii, Yuzuru
Luminous infrared galaxies (LIRGs) are enshrouded by a large amount of dust produced by their active star formation, and it is difficult to measure their activity in optical wavelengths. We have carried out Pa? narrow-band imaging observations of 38 nearby star forming galaxies including 33 LIRGs listed in the IRAS Revised Bright Galaxy Sample catalog with the Atacama Near InfraRed camera on the University of Tokyo Atacama Observatory (TAO) 1.0 m telescope (miniTAO). Star formation rates (SFRs) estimated from the Pa? fluxes, corrected for dust extinction using the Balmer decrement method (typically AV ~ 4.3 mag), show a good correlation with those from the bolometric infrared luminosity of the IRAS data within a scatter of 0.27 dex. This suggests that the correction of dust extinction for the Pa? flux is sufficient in our sample. We measure the physical sizes and surface densities of infrared luminosities (? L(IR)) and the SFR (?SFR) of star forming regions for individual galaxies, and we find that most of the galaxies follow a sequence of local ultra-luminous or luminous infrared galaxies (U/LIRGs) on the L(IR)-? L(IR) and SFR-?SFR plane. We confirm that a transition of the sequence from normal galaxies to U/LIRGs is seen at L(IR) = 8 ū 1010 L ?. Also, we find that there is a large scatter in physical size, different from normal galaxies or ULIRGs. Considering the fact that most U/LIRGs are merging or interacting galaxies, this scatter may be caused by strong external factors or differences in their merging stages.
Stability of a reflective coupling diode with the inclusion of thermal effects in narrow band-gap This article has been downloaded from IOPscience. Please scroll down to see the full text article.
Gilbert, Matthew
Stability of a reflective coupling diode with the inclusion of thermal effects in narrow band-1242(04)72447-5 Stability of a reflective coupling diode with the inclusion of thermal effects in narrow band-gap materials the difficulty in fabrication, resonant tunnelling diodes (RTD) have found a great deal of usage in the analogue
CH Hot Bands in the Near-IR Emission Spectra of the Leonids
Friedemann T. Freund; John Scoville; Reimer Holm; Rudolf Seelemann; Minoru M. Freund
The reported infrared (IR) emission spectra from 1999 Leonid fireballs show a 3.4mum C-H emission band and unidentified bands at longer wavelengths. Upon atmospheric entry, the Leonid meteorites were flash-heated to temperatures around 2400K, which would destroy any organics on the surface of the meteorite grains. We propose that the vcH emission hand in the Leonid emission spectra arises from
VLF-emissions from ring current electrons. An interpretation of the band of missing emissions
NASA Technical Reports Server (NTRS)
Maeda, K.; Smith, P. H.; Anderson, R. R.
VLF-emissions associated with the enhancement of ring current electrons during magnetic storms and substorms which were detected by the equatorially orbiting S-A satellite (Explorer 45) are described. The emissions observed near the geomagnetic equator consist of essentially two frequency regimes, i.e., one above the electron gyrofrequency, f sub H at the equator and the other below f sub H. This is indicated as a part of the wide-band data obtained during the main phase of the December 17, 1971 magnetic storm. The upper figure is the ac-magnetic field data measured by the search-coil magnetometer with the upper cutoff of 3kHz and the lower figure is the ac-electric field data obtained by the electric field sensor with the upper cutoff of 10kHz. These figures show the time sequence of the observed emissions along the inbound orbit (No. 101) of the satellite as f sub H changes approximately from 3 kHz at 20 UT to 6 kHz at 21 UT. The emissions above f sub H are electrostatic mode, which peak near the frequencies of (n + 1/2) f sub H where n is positive integer, and sometimes emissions up to n = 10 are observed. The emissions below f sub H are whistler mode, which have a conspicuous gap along exactly half electron gyrofrequency, f sub H/2.
New algorithms for the detection and elimination of sine waves and other narrow-band signals in the presence of broadband signals and noise
NASA Astrophysics Data System (ADS)
Soderstrand, Michael A.; Rangarao, K. V.; Loomis, H. H.
Four different classes of adaptive signal cancelers can be used to eliminate narrow-band interference from a broadband signal: (1) cascaded second-order notch filters; (2) high-order in-line notch filters; (3) second-order bandpass noise cancelers; and (4) high-order bandpass noise cancelers. Of the four, a structure based on second-order bandpass filters used as signal cancelers is found to perform better than the other structures. An adaptive algorithm for these filters has been proposed. The structure can be reduced in hardware complexity without degrading performance using a new adaptive algorithm that out-performs any of the other known structures or algorithms. This new structure is particularly suited to the elimination of narrow-band interference in broadband Bi-Phase Shift-Key (BPSK) signals with and without background noise.
LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Measurement of the surface wavelength distribution of narrow-band radiation by a colorimetric method
NASA Astrophysics Data System (ADS)
Kraiskii, A. V.; Mironova, T. V.; Sultanov, T. T.
A method is suggested for determining the wavelength of narrow-band light from a digital photograph of a radiating surface. The digital camera used should be appropriately calibrated. The accuracy of the wavelength measurement is better than 1 nm. The method was tested on the yellow doublet of mercury spectrum and on the adjacent continuum of the incandescent lamp radiation spectrum. By means of the method suggested the homogeneity of holographic sensor swelling was studied in stationary and transient cases.
Xenon chloride ultraviolet B laser is more effective in treating psoriasis and in inducing T cell apoptosis than narrow-band ultraviolet B
Zoltßn Novßk; Bķla B¾nis; Eszter Baltßs; Imre Ocsovszki; Ferenc Ignßcz; Attila Dobozy; Lajos Kemķny
Earlier we reported that a 308-nm xenon chloride (XeCl) UVB laser is highly effective for treating psoriasis. As ultraviolet B light seems to cause T cell apoptosis, in the present study we studied the ability of the XeCl laser to induce T-cell apoptosis in vitro, and then compared the apoptosis-inducing capacities of narrow-band UVB (NB-UVB) light and the XeCl laser.
Tuning the narrow-band beam position monitor sampling clock to remove the aliasing errors in APS storage ring orbit measurements
X. Sun; O. Singh
The Advanced Photon Source storage ring employs a real-time orbit correction system to reduce orbit motion up to 50 Hz. This system uses up to 142 narrow-band rf beam position monitors (Nbbpms) in a correction algorithm by sampling at a frequency of 1.53 kHz. Several Nbbpms exhibit aliasing errors in orbit measurements, rendering these Nbbpms unusable in real-time orbit feedback.
electromag- netic plasma waves, known as extremely low frequency/very low frequency (ELF/VLF) chorusSOURCE REGION CHARACTERISTICS OF MAGNETOSPHERIC ELF/VLF BANDED CHORUS EMISSIONS A DISSERTATION appears in two distinct frequency bands separated by an emission gap, which occurs where the wave power
. Natural electromag- netic plasma waves, known as extremely low frequency/very low frequency (ELFSOURCE REGION CHARACTERISTICS OF MAGNETOSPHERIC ELF/VLF BANDED CHORUS EMISSIONS A DISSERTATION the plasmapause, often appears in two distinct frequency bands separated by an emission gap, which occurs where
Detection of marine methane emissions with AVIRIS band ratios
NASA Astrophysics Data System (ADS)
Bradley, Eliza S.; Leifer, Ira; Roberts, Dar A.; Dennison, Philip E.; Washburn, Libe
The relative source contributions of methane (CH4) have high uncertainty, creating a need for local-scale characterization in concert with global satellite measurements. However, efforts towards methane plume imaging have yet to provide convincing results for concentrated sources. Although atmospheric CH4 mapping did not motivate the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) design, recent studies suggest its potential for studying concentrated CH4 sources such as the Coal Oil Point (COP) seep field (ś0.015 Tg CH4 yr-1) offshore Santa Barbara, California. In this study, we developed a band ratio approach on high glint COP AVIRIS data and demonstrate the first successful local-scale remote sensing mapping of natural atmospheric CH4 plumes. Plume origins closely matched surface and sonar-derived seepage distributions, with plume characteristics consistent with wind advection. Imaging spectrometer data may also be useful for high spatial-resolution characterization of concentrated, globally-significant CH4 emissions from offshore platforms and cattle feedlots.
Turboprop and rotary-wing aircraft flight parameter estimation using both narrow-band and broadband passive acoustic signal-processing methods.
Ferguson, B G; Lo, K W
Flight parameter estimation methods for an airborne acoustic source can be divided into two categories, depending on whether the narrow-band lines or the broadband component of the received signal spectrum is processed to estimate the flight parameters. This paper provides a common framework for the formulation and test of two flight parameter estimation methods: one narrow band, the other broadband. The performances of the two methods are evaluated by applying them to the same acoustic data set, which is recorded by a planar array of passive acoustic sensors during multiple transits of a turboprop fixed-wing aircraft and two types of rotary-wing aircraft. The narrow-band method, which is based on a kinematic model that assumes the source travels in a straight line at constant speed and altitude, requires time-frequency analysis of the acoustic signal received by a single sensor during each aircraft transit. The broadband method is based on the same kinematic model, but requires observing the temporal variation of the differential time of arrival of the acoustic signal at each pair of sensors that comprises the planar array. Generalized cross correlation of each pair of sensor outputs using a cross-spectral phase transform prefilter provides instantaneous estimates of the differential times of arrival of the signal as the acoustic wavefront traverses the array. PMID:11051503
Narrow-band emission in Thomson sources operating in the high-field regime.
Terzi?, BalÜa; Deitrick, Kirsten; Hofler, Alicia S; Krafft, Geoffrey A
We present a novel and quite general analysis of the interaction of a high-field chirped laser pulse and a relativistic electron, in which exquisite control of the spectral brilliance of the up-shifted Thomson-scattered photon is shown to be possible. Normally, when Thomson scattering occurs at high field strengths, there is ponderomotive line broadening in the scattered radiation. This effect makes the bandwidth too large for some applications and reduces the spectral brilliance. We show that such broadening can be corrected and eliminated by suitable frequency modulation of the incident laser pulse. Furthermore, we suggest a practical realization of this compensation idea in terms of a chirped-beam-driven free electron laser oscillator configuration and show that significant compensation can occur, even with the imperfect matching to be expected in these conditions. PMID:24579606
Accuracy of Narrow Band Imaging with Colonoscopy Allows for Distal Non-Cancerous Polyps to Be Left in Place
... na hyperplastic ( -cancerous po idate NBI crit yp histology. -reviewed sci nd adenomas. e cancer risk. ectal ... objectives were to assess the accuracy of predicting histology (tissue composition or polyp type) by using narrow ...
Ge Junqiang; Hu Chen; Wang Jianmin; Zhang Shu [Key Laboratory for Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences, 19B Yuquan Road, Beijing 100049 (China); Bai Jinming, E-mail: email@example.com [Yunnan Observatory, Chinese Academy of Sciences, Kunming 650011 (China)
Recently, much attention has been paid to double-peaked narrow emission-line (NEL) galaxies, some of which are suggested to be related to merging galaxies. We make a systematic search to build the largest sample of these sources from Data Release 7 of the Sloan Digital Sky Survey (SDSS). With reasonable criteria for fluxes, FWHMs of the emission lines, and separations of the peaks, we select 3030 double-peaked NEL galaxies. In light of the existence of broad Balmer lines and the locations of the two components of double-peaked NELs distinguished by the Kauffmann et al. criteria in the Baldwin-Phillips-Terlevich diagram, we find that there are 81 Type I active galactic nuclei (AGNs), 837 double Type II AGNs (2-Type II), 708 galaxies with double star-forming components (2-SF), 400 with mixed star-forming and Type II AGN components (Type II + SF), and 1004 unknown-type objects. As a by-product, a sample of galaxies (12,582) with asymmetric or top-flat profiles of emission lines is established. After visually inspecting the SDSS images of the two samples, we find 54 galaxies with dual cores. The present samples can be used to study the dynamics of merging galaxies, the triggering mechanism of black hole activity, the hierarchical growth of galaxies, and the dynamics of narrow line regions driven by outflows and a rotating disk.
Using Lunar Observations to Assess Terra MODIS Thermal Emissive Bands Calibration
NASA Technical Reports Server (NTRS)
Xiong, Xiaoxiong; Chen, Hongda
MODIS collects data in both the reflected solar and thermal emissive regions using 36 spectral bands. The center wavelengths of these bands cover the3.7 to 14.24 micron region. In addition to using its on-board calibrators (OBC), which include a full aperture solar diffuser (SD) and a blackbody (BB), lunar observations have been scheduled on a regular basis to support both Terra and Aqua MODIS on-orbit calibration and characterization. This paper provides an overview of MODIS lunar observations and their applications for the reflective solar bands (RSB) and thermal emissive bands (TEB) with an emphasis on potential calibration improvements of MODIS band 21 at 3.96 microns. This spectral band has detectors set with low gains to enable fire detection. Methodologies are proposed and examined on the use of lunar observations for the band 21 calibration. Also presented in this paper are preliminary results derived from Terra MODIS lunar observations and remaining challenging issues.
RFID Transponders' RF Emissions in Aircraft Communication and Navigation Radio Bands
NASA Technical Reports Server (NTRS)
Nguyen, Truong X.; Ely, Jay J.; Koppen Sandra V.; Fersch, Mariatheresa S.
Radiated emission data in aircraft communication and navigation bands are presented for several active radio frequency identification (RFID) tags. The individual tags are different in design, operation and transmitting frequencies. The process for measuring the tags emissions in a reverberation chamber is discussed. Measurement issues dealing with tag interrogation, low level measurement in the presence of strong transmissions, and tags low duty factors are discussed. The results show strong emissions, far exceeding aircraft emission limits and can be of potential interference risks.
Shocked Post-starbust Galaxy Survey: Candidate Post-Starbust Galaxies with Narrow Emission Line Ratios Arising from Shocks
NASA Astrophysics Data System (ADS)
Cales, Sabrina; Alatalo, Katherine A.; Appleton, Philip N.; Lisenfeld, Ute; Rich, Jeffrey; Nyland, Kristina; Lacy, Mark; Kewley, Lisa J.
As galaxies age they move from the blue cloud (star forming) to the red sequence (`dead' galaxies) in the color-magnitude diagram of galaxies. Galaxies between the blue cloud and red sequence (i.e., the green valley) are caught in the act of transitioning and they show large Balmer jump and high order Balmer absorption lines in their optical spectra. These galaxies answer to many names (i.e., E+A, K+A, Hdelta-strong, post-starburst), all with similar but slightly different selection criteria. Many studies of transitioning galaxies invoke strong constraints on emission lines in order to guarantee a dominant post-starburst (rather that actively star bursting) stellar population, however these constraints bias the sample against narrow-line emission not arising from star formation, namely active galactic nuclei, low-ionization nuclear emission regions and shocks. Using the Oh-Sarzi-Schawinski-Yi (OSSY) emission and absorption line measurements for SDSS DR7 galaxies we study the intersection between transitioning galaxies and those with shock line ratios. We show that a significant fraction of transitioning galaxies have emission-line ratios indicative of shocks. We postulate that these shocks may be in part responsible for the shepherding of blue star forming galaxies to passive early-types.
Defect-Band Emission Photoluminescence Imaging on Multi-Crystalline Si Solar Cells: Preprint
Yan, F.; Johnston, S.; Zaunbrecher, K.; Al-Jassim, M.; Sidelkheir, O.; Blosse, A.
Defect-band photoluminescence (PL) imaging with an InGaAs camera was applied to multicrystalline silicon (mc-Si) wafers, which were taken from different heights of different Si bricks. Neighboring wafers were picked at six different processing steps, from as-cut to post-metallization. By using different cut-off filters, we were able to separate the band-to-band emission images from the defect-band emission images. On the defect-band emission images, the bright regions that originate from the grain boundaries and defect clusters were extracted from the PL images. The area fraction percentage of these regions at various processing stages shows a correlation with the final cell electrical parameters.
Transient increase of the energy gap of superconducting NbN thin films excited by resonant narrow-band terahertz pulses.
Beck, M; Rousseau, I; Klammer, M; Leiderer, P; Mittendorff, M; Winnerl, S; Helm, M; Gol'tsman, G N; Demsar, J
Observations of radiation-enhanced superconductivity have thus far been limited to a few type-I superconductors (Al, Sn) excited at frequencies between the inelastic scattering rate and the superconducting gap frequency 2?/h. Utilizing intense, narrow-band, picosecond, terahertz pulses, tuned to just below and above 2?/h of a BCS superconductor NbN, we demonstrate that the superconducting gap can be transiently increased also in a type-II dirty-limit superconductor. The effect is particularly pronounced at higher temperatures and is attributed to radiation induced nonthermal electron distribution persisting on a 100Āps time scale. PMID:23848912
Observation of Coherently-Enhanced Tunable Narrow-Band Terahertz Transition Radiation from a Relativistic Sub-Picosecond Electron Bunch Train
Piot, P [Northern Illinois U.; Fermilab; Sun, Y E [Fermilab; Maxwell, T J [Fermilab; Northern Illinois U.; Ruan, J.; Lumpkin, A H [Fermilab; Rihaoui, M M [Northern Illinois U.; Thurman-Keup, R [Fermilab
We experimentally demonstrate the production of narrow-band (?f/f ~ =20% at f ~ = 0.5 THz) THz transition radiation with tunable frequency over [0.37, 0.86] THz. The radiation is produced as a train of sub-picosecond relativistic electron bunches transits at the vacuum-aluminum interface of an aluminum converter screen. We also show a possible application of modulated beams to extend the dynamical range of a popular bunch length diagnostic technique based on the spectral analysis of coherent radiation.
Comparative study of conventional colonoscopy, magnifying chromoendoscopy, and magnifying narrow-band imaging systems in the differential diagnosis of small colonic polyps between trainee and experienced endoscopist
Chun-Chao Chang; Ching-Ruey Hsieh; Horng-Yuan Lou; Chia-Lang Fang; Cheng Tiong; Jen-Juh Wang; I-Van Wei; Shie-Chiang Wu; Jun-Nan Chen; Yuan-Hung Wang
BackgroundĀĀRemoval of colorectal neoplastic polyps can reduce the incidence of colorectal cancers. It is important to distinguish neoplastic\\u000a from nonneoplastic polyps. We compared the ability of a trainee and an experienced endoscopist in distinguishing between neoplastic\\u000a polyps and nonneoplastic polyps by conventional white-light, magnifying narrow-band imaging (NBI), and magnifying chromoendoscopy.\\u000a \\u000a \\u000a \\u000a Materials and methodsĀĀOne hundred and sixty-three small colorectal polyps from
Characterization of Al and Mg alloys from their x-ray emission bands
is expected to reduce the weight of vehicles and the fuel consumption, which will reduce air pollution in a practical perspective as it is in a fundamental point of view. We study the emission bands of various dilute
Unprecedentedly Strong and Narrow Electromagnetic Emissions Stimulated by High-Frequency Radio Waves in the Ionosphere
Norin, L.; Leyser, T. B.; Nordblad, E.; Thide, B.; McCarrick, M. [Swedish Institute of Space Physics, Uppsala (Sweden); BAE Systems Advanced Technologies, Washington, D.C. (United States)
Experimental results of secondary electromagnetic radiation, stimulated by high-frequency radio waves irradiating the ionosphere, are reported. We have observed emission peaks, shifted in frequency up to a few tens of Hertz from radio waves transmitted at several megahertz. These emission peaks are by far the strongest spectral features of secondary radiation that have been reported. The emissions are attributed to stimulated Brillouin scattering, long predicted but hitherto never unambiguously identified in high-frequency ionospheric interaction experiments. The experiments were performed at the High-Frequency Active Auroral Research Program (HAARP), Alaska, USA.
The extended narrow line region of NGC 4151. I - Emission line ratios and their implications
NASA Astrophysics Data System (ADS)
Penston, M. V.; Robinson, A.; Alloin, D.; Appenzeller, I.; Aretxaga, I.; Axon, D. J.; Baribaud, T.; Barthel, P.; Baum, S. A.; Boisson, C.; de Bruyn, A. G.; Clavel, J.; Colina, L.; Dennefeld, M.; Diaz, A.; Dietrich, M.; Durret, F.; Dyson, J. E.; Gondhalekar, P.; van Groningen, E.; Jablonka, P.; Jackson, N.; Kollatschny, W.; Laurikainen, E.; Lawrence, A.; Masegosa, J.; McHardy, I.; Meurs, E. J. A.; Miley, G.; Moles, M.; O'Brien, P.; O'Dea, C.; del Olmo, A.; Pedlar, A.; Perea, J.; Perez, E.; Perez-Fournon, I.; Perry, J.; Pilbratt, G.; Rees, M.; Robson, I.; Rodriguez-Pascual, P.; Rodriguez Espinosa, J. M.; Santos-Lleo, M.; Schilizzi, R.; Stasi?ska, G.; Stirpe, G. M.; Tadhunter, C.; Terlevich, E.; Terlevich, R.; Unger, S.; Vila-Vilaro, V.; Vilchez, J.; Wagner, S. J.; Ward, M. J.; Yates, G. J.
The paper presents the first results from long-slit spectra of the Seyfert galaxy NGC 4151 which give average diagnostic ratios of weak lines in the Extended Narrow Line Region (ENLR) of the galaxy and the first direct density measurement in an ENLR. These data confirm that the ENLR is kinematically undisturbed gas in the disk of the galaxy which is illuminated by an ionizing continuum stronger by a factor of 13 than a power law interpolated between recently observed ultraviolet and X-ray fluxes. Explanations of this apparent excess include a hot thermal continuum, time variations, and an anisotropic rotation field.
Quasi-random narrow-band model fits to near-infrared low-temperature laboratory methane spectra and derived exponential-sum absorption coefficients
NASA Technical Reports Server (NTRS)
Baines, Kevin H.; West, Robert A.; Giver, Lawrence P.; Moreno, Fernando
Near-infrared 10/cm resolution spectra of methane obtained at various temperatures, pressures, and abundances are fit to a quasi-random narrow-band model. Exponential-sum absorption coefficients for three temperatures (112, 188, and 295 K), and 20 pressures from 0.0001 to 5.6 bars, applicable to the cold environments of the major planets, are then derived from the band model for the 230 wavelengths measured from 1.6 to 2.5 microns. RMS deviations between the laboratory and the exponential-sum synthetic transmissions are reported for the best fitting 50 wavelengths. Deviations relevant to broadband, 1-percent spectral resolution observations are also presented. The validity of exponential-sum coefficients derived from broadband (10/cm) transmission data is demonstrated via direct comparison with line-by-line calculations. The complete atlas of coefficients is available from the Planetary Data System-Planetary Atmospheres Discipline Node.
Analysis of emission data from a broad-band radiometer
NASA Astrophysics Data System (ADS)
Ti, Soi-Sang; Tudini, Adrian; Oermann, Ray
The principles of analysis of emission data from a broadband radiometer are outlined. The errors arising from the analysis are also discussed and illustrated. In general, in the determination of radiant output of an emitter using a broadband radiometer, errors unknown magnitude will occur unless the spectral emission profile of the calibration source is matched to that of the emitter.
N2 triplet band emissions in the dayglow of Venus, Mars, and Titan
NASA Astrophysics Data System (ADS)
Jain, Sonal Kumar; Bhardwaj, Anil
Vegard-Kaplan (VK) and Second Positive emissions of N_2 are common features in the terrestrial dayglow and aurora and have been studied extensively. Recent discoveries of N_2 triplet band emissions on Mars by SPICAM/Mars-Express and on Titan by Cassini UVIS have led planetary scientists to look for the processes governing the N_2 triplet band emissions in different planetary atmospheres. Present work deals with the modeling of N_2 triplet band emission on Mars, Venus, and Titan. A model for N_2 triplet band emissions has been developed and used to explain the recent observations of N_2 Vegard-Kaplan (VK) (A^3?_u^+ - X^1?^+_g ) band on Mars and Titan. Steady state photoelectron fluxes and volume excitation rates have been calculated using the Analytical Yield Spectra technique. Since interstate cascading is important for triplet states of N_2, the population of any given level of N_2 triplet states is calculated under statistical equilibrium considering direct excitation, cascading, and quenching effects. Relative population of all vibrational levels of each triplet state is calculated in the model. Line of sight intensities and height-integrated overhead intensities have been calculated for VK, First Positive ( B^3?_g - A^3?^+_u ), Second Positive ( C^3?_u - B^3?_g ), Wu-Benesch (W^3?_u - B^3?_g), Reverse First Positive, Herman--Kaplan (E ? A), E ? B, and E ? C bands of N_2. The N_2 VK band span wavelength range from far ultraviolet to visible, and some transitions even originate at wavelength more than 1000 nm . Our calculations show that the overhead intensity of VK bands in the wavelength range 400--800, 300--190, 200--300, and 150--200 nm are 22%, 39%, 35%, and 4% of the total VK band emission. Emissions between 600 and 800 nm wavelength consist of about 50% of the total First Positive band system. Major portion of Second Positive band emissions lie in wavelengths between 300 and 400 nm, which is more than 90% of the total Second Positive band overhead intensity. On Mars, a reduction in the N_2 density by a factor of 3 in the Mars thermospheric general circulation model is required to obtain agreement between calculated limb profiles of VK (0-6) and the SPICAM/MEX observation. On Titan, the calculated intensity of N_2 VK band in 150--190 nm wavelength range is in good agreement with the Cassini-UVIS observation. Calculations are also carried out on Venus using this model. Calculated intensities on Venus are about factor of 10 higher than that on Mars. The results will be presented and discussed.
Preparation of Narrow Band-Gap Cu2Sn(S,Se)3 and Fabrication of Film by Non-Vacuum Process
NASA Astrophysics Data System (ADS)
Nomura, Takeshi; Maeda, Tsuyoshi; Wada, Takahiro
We successfully prepared a Cu2Sn(S1-xSex)3 (CTSSe) solid solution with 0?x?1.0. CTSSe solid solution powders were synthesized by mixing the elemental powders and post-annealing at 600 ░C. The crystal structure of Cu2SnS3 (CTS) was characterized by Rietveld refinement of the powder X-ray diffraction data and determined to be a monoclinic crystal system. The band gaps of CTSSe solid solution were determined by the diffuse reflectance spectra of the powder samples and the transmittance spectrum of the film fabricated by a non-vacuum thin-film fabrication process called printing and high-pressure sintering (PHS). The band gap (Eg) of CTS is 0.87 eV, which is in good agreement with the recently reported value of monoclinic CTS film. The band gap of the Cu2Sn(S1-xSex)3 solid solution linearly decreases from 0.87 eV (x = 0.0) to 0.67 eV (x = 0.6) with increasing Se content. The CTSSe solid solution has potential as a narrow band-gap absorber material for thin-film full spectrum solar cells.
Narrow-Band Imaging System for the Multi-application Solar Telescope at Udaipur Solar Observatory: Characterization of Lithium Niobate Etalons
NASA Astrophysics Data System (ADS)
Raja Bayanna, A.; Mathew, Shibu K.; Venkatakrishnan, P.; Srivastava, N.
Multi-application Solar Telescope is a 50 cm off-axis Gregorian telescope that has been installed at the lake site of Udaipur Solar Observatory. For quasi-simultaneous photospheric and chromospheric observations, a narrow-band imager has been developed as one of the back-end instruments for this telescope. Narrow-band imaging is achieved using two lithium niobate Fabry-Perot etalons working in tandem as a filter. This filter can be tuned to different wavelengths by changing either voltage, tilt or temperature of the etalons. To characterize the etalons, a Littrow spectrograph was set up, in conjunction with a 15 cm Carl Zeiss Coud\\'e solar telescope. The etalons were calibrated for the solar spectral lines FeI 6173 {\\AA}, and CaII 8542 {\\AA}. In this work, we discuss the characterization of the Fabry-Perot etalons, specifically the temperature and voltage tuning of the system for the spectral lines proposed for observations. We present the details of the calibration set-up and various tuning parameters. We also present solar images obtained using the system parameters. We also present solar images obtained using the system.
Resonance response of a single-degree-of-freedom nonlinear vibro-impact system to a narrow-band random parametric excitation
NASA Astrophysics Data System (ADS)
Su, Min-Bang; Rong, Hai-Wu
The resonant response of a single-degree-of-freedom nonlinear vibro-impact oscillator with a one-sided barrier to a narrow-band random parametric excitation is investigated. The narrow-band random excitation used here is a bounded random noise. The analysis is based on a special Zhuravlev transformation, which reduces the system to one without impacts, thereby permitting the applications of random averaging over ōfast" variables. The averaged equations are solved exactly and an algebraic equation of the amplitude of the response is obtained for the case without random disorder. The methods of linearization and moment are used to obtain the formula of the mean-square amplitude approximately for the case with random disorder. The effects of damping, detuning, restitution factor, nonlinear intensity, frequency and magnitude of random excitations are analysed. The theoretical analyses are verified by numerical results. Theoretical analyses and numerical simulations show that the peak response amplitudes will reduce at large damping or large nonlinear intensity and will increase with large amplitude or frequency of the random excitations. The phenomenon of stochastic jump is observed, that is, the steady-state response of the system will jump from a trivial solution to a large non-trivial one when the amplitude of the random excitation exceeds some threshold value, or will jump from a large non-trivial solution to a trivial one when the intensity of the random disorder of the random excitation exceeds some threshold value.
Connection between Mid-infrared Emission Properties and Narrow-line Region Outflows in Type 1 Active Galactic Nuclei
NASA Astrophysics Data System (ADS)
Zhang, Kai; Wang, Ting-Gui; Yan, Lin; Dong, Xiao-Bo
The location of warm dust producing the mid-infrared (MIR) emission in type 1 active galactic nuclei (AGNs) is complex and not yet fully known. We explore this problem by studying how the MIR covering factor (CFMIR = L MIR/L bol) correlates with the fundamental parameters of AGN accretion process (such as L bol, black hole mass M BH, and Eddington ratio L/L Edd) and the properties of narrow emission lines (as represented by [O III] ?5007), using large data sets derived from the Sloan Digital Sky Spectroscopic Survey (SDSS) and the Wide Infrared Sky Survey (WISE). First, we find that the luminosity of the [O III] wing component (L wing) correlates more tightly with the continuum luminosity (?L ?(5100)) than the luminosity of the line core component (L core) does, which is in line with our previous conclusion that the wing component, generally blueshifted, originates from the polar outflows in the inner narrow-line region (NLR). We then find that the MIR CF shows the strongest correlation with L wing/L bol rather than with L core/L bol or the above fundamental AGN parameters, and the correlation becomes stronger as the infrared wavelength increases. We also confirm the anti-correlations of CFMIR with L bol and M BH, and the lack of dependence of CFMIR on the Eddington ratio. These results suggest that a large fraction of the warm dust producing MIR emission in AGNs is likely embedded in polar outflows in the NLR instead of in the torus.
Zhang Kai; Wang Tinggui; Dong Xiaobo [Key Laboratory for Research in Galaxies and Cosmology, University of Sciences and Technology of China, Chinese Academy of Sciences, Hefei, Anhui 230026 (China); Yan Lin, E-mail: firstname.lastname@example.com [Spitzer Science Center, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125 (United States)
The location of warm dust producing the mid-infrared (MIR) emission in type 1 active galactic nuclei (AGNs) is complex and not yet fully known. We explore this problem by studying how the MIR covering factor (CF{sub MIR} = L{sub MIR}/L{sub bol}) correlates with the fundamental parameters of AGN accretion process (such as L{sub bol}, black hole mass M{sub BH}, and Eddington ratio L/L{sub Edd}) and the properties of narrow emission lines (as represented by [O III] {lambda}5007), using large data sets derived from the Sloan Digital Sky Spectroscopic Survey (SDSS) and the Wide Infrared Sky Survey (WISE). First, we find that the luminosity of the [O III] wing component (L{sub wing}) correlates more tightly with the continuum luminosity ({lambda}L{sub {lambda}}(5100)) than the luminosity of the line core component (L{sub core}) does, which is in line with our previous conclusion that the wing component, generally blueshifted, originates from the polar outflows in the inner narrow-line region (NLR). We then find that the MIR CF shows the strongest correlation with L{sub wing}/L{sub bol} rather than with L{sub core}/L{sub bol} or the above fundamental AGN parameters, and the correlation becomes stronger as the infrared wavelength increases. We also confirm the anti-correlations of CF{sub MIR} with L{sub bol} and M{sub BH}, and the lack of dependence of CF{sub MIR} on the Eddington ratio. These results suggest that a large fraction of the warm dust producing MIR emission in AGNs is likely embedded in polar outflows in the NLR instead of in the torus.
Si3N4 emissivity and the unidentified infrared bands
NASA Technical Reports Server (NTRS)
Russell, Ray W.; Chatelain, M. A.; Hecht, James H.; Stephens, John R.
Infrared spectroscopy of warm (about 150 to 750 K), dusty astronomical sources has revealed a structured emission spectrum which can be diagnostic of the composition, temperature, and in some cases, even size and shape of the grains giving rise to the observed emission. The identifications of silicate emission in oxygen rich objects and SiC in carbon rich object are two examples of this type of analysis. Cometary spectra at moderate resolution have similarly revealed silicate emission, tying together interstellar and interplanetary dust. However, Goebel has pointed out that some astronomical sources appear to contain a different type of dust which results in a qualitatively different spectral shape in the 8 to 13 micron region. The spectra shown make it appear unlikely that silicon nitride can be identified as the source of the 8 to 13 micron emission in either NGC 6572 or Nova Aql 1982. The similarity between the general wavelength and shape of the 10 micron emission from some silicates and that from the two forms of silicon nitride reported could allow a mix of cosmic grains which include some silicon nitride if only the 8 to 13 micron data are considered.
Band gap narrowing in nitrogen-doped La2Ti2O7 predicted by density-functional theory calculations.
Zhang, Junying; Dang, Wenqiang; Ao, Zhimin; Cushing, Scott K; Wu, Nianqiang
In order to reveal the origin of enhanced photocatalytic activity of N-doped La2Ti2O7 in both the visible light and ultraviolet light regions, its electronic structure has been studied using spin-polarized conventional density functional theory (DFT) and the Heyd-Scuseria-Ernzerhof (HSE06) hybrid approach. The results show that the deep localized states are formed in the forbidden band when nitrogen solely substitutes for oxygen. Introducing the interstitial Ti atom into the N-doped La2Ti2O7 photocatalyst still causes the formation of a localized energy state. Two nitrogen substitutions co-exist stably with one oxygen vacancy, creating a continuum energy band just above the valence band maximum. The formation of a continuum band instead of mid-gap states can extend the light absorption to the visible light region without increasing the charge recombination, explaining the enhanced visible light performance without deteriorating the ultraviolet light photocatalytic activity. PMID:25751702
Techniques to minimize adjacent band emissions from Earth Exploration Satellites to protect the Space Research (Category B) Earth Stations in the 8400-8450 MHz band
NASA Technical Reports Server (NTRS)
Wang, Charles C.; Sue, Miles K.; Manshadi, Farzin
The Earth Exploration Satellites operating in the 8025-8400 MHz band can have strong adjacent band emissions on the8400-8450 MHz band which is allocated for Space Research (Category-B). The unwanted emission may exceed the protection criterion establish by the ITU-R for the protection of the Space Research (Category B) earth stations, i.e., deep-space earth stations. An SFCG Action Item (SF 23/14) was created during the 23rd SFCG meeting to explore technical and operational techniques to reduce the adjacent band emissions. In response to this action item, a study was conducted and results are presented in this document.
High-power narrow-band operation and Raman frequency conversion of an electron-beam pumped krypton excimer laser
NASA Astrophysics Data System (ADS)
Kurosawa, Kou; Sasaki, Wataru; Fujiwara, Etsuo; Kato, Yoshiaki
A Kr excimer laser pumped by a relativistic electron beam has generated high-power output by using a cavity composed of a Si mirror and MgF2 mirror. The threshold gas pressure for laser oscillation is 10 atm, and the maximum output power achieved so far is 6.6 MW at 15 atm. The maximum power is limited by the surface damages on the mirrors. This laser output, oscillating at 145.7 nm, has a spectral width of 0.8 nm (FWHM). Efficient spectral narrowing down to 0.1 nm has been achieved with a 32 deg apex angle MgF2 prism inserted in the cavity giving 3.5 MW peak power at 15 atm of Kr gas pressure. Wavelength conversion by stimulated Raman scattering in high-pressure H2 has been demonstrated for efficient extension of the laser wavelength.
The origin of N III lambda 990 and C III lambda 977 emission in AGN narrow-line region gas
NASA Technical Reports Server (NTRS)
Ferguson, J. W.; Ferland, G. J.; Pradhan, A. K.
We discuss implications of Hopkins Ultraviolet Telescope (HUT) detections of C III lambda 977 and N III lambda 990 emission from the narrow-line region of the Seyfert 2 galaxy NGC 1068. In their discovery paper Kriss et al. showed that the unexpectedly great strength of these lines implies that the emitting gas must be shock-heated if the lines are collisionally excited. Here we investigate other processes which excite these lines in photoionization equilibrium. Recombination, mainly dielectronic, and continuum fluorescence are strong contributors to the line. The resulting intensities are sensitive to the velocity field of the emitting gas and require that the turbulence be of the same order of magnitude as the observed line width. We propose optical observations that will decide whether the gas is collisionally or radiatively heated.
Valence-band energy spectrum of solid solutions of narrow-gap-semiconductor Bi2-xSnxTe3 single crystals
NASA Astrophysics Data System (ADS)
Kulbachinskii, V. A.; Inoue, M.; Sasaki, M.; Negishi, H.; Gao, W. X.; Takase, K.; Giman, Y.; Lostak, P.; Horak, J.
Electrical resistivities along the C2 and C3 axes, Hall effect, Shubnikov-de Haas effect, and pulsed-laser-induced transient thermoelectric effect (TTE) have been measured in the temperature range 4.2-300 K for solid solutions of narrow-gap p-type Bi2-xSnxTe3 (0<=x<=0.035) single crystals. We have found systematic variations of the hole concentration, Hall mobility, Dingle temperature, and cyclotron mass with increasing Sn content. By doping Sn atoms, the hole Fermi energy of the upper valence band (UVB) is increased and a Sn-induced impurity band is formed near the top of the lower valence band (LVB) lying by about 15 meV below the top of the UVB. The observed TTE voltages decay exponentially with time, showing a multiple relaxation process with characteristic relaxation times for thermal diffusions of photogenerated carriers. The TTE data show that there are at least four different relaxation times (?1-?4) due to holes, and two, ?5 and ?6, due to electrons. Combined with the transport data, as well as the existing band model, we have evaluated the effective masses m*1~=0.033m0 and m*2~=0.060m0 for the many-valley hole Fermi surfaces of the UVB, as well as two effective masses m*3~=0.16m0 and m*4~=0.31m0 for the LVB along the C2 direction, corresponding to ?1-?4, respectively. Discussion will be given for the energy spectrum and anisotropy in the UVB and LVB, as well as the lower electron band, in this material system. The thermal conductivities for holes and lattices are also evaluated from the TTE data.
First results from the FPGA/NIOS Adaptive FIR Filter Using Linear Prediction Implemented in the AERA Radio Stations to Reduce Narrow Band RFI for Radio Detection of Cosmic Rays
Zbigniew Szadkowski; D. G?as; C. Timmermans; T. Wijnen for the Pierre Auger Collaboration
The FPGA/NIOS FIR filter based on linear prediction (LP) to suppress radio frequency interference (RFI) has been installed in several radio stations in the Auger Engineering Radio Array (AERA) experiment. AERA observes coherent radio emission from extensive air showers induced by ultra-high-energy cosmic rays to make a detailed study of the development of the electromagnetic part of air showers. Radio signals provide complementary information to that obtained from Auger surface detectors, which are predominantly sensitive to the particle content of an air shower at the surface. The radio signals from air showers are caused by the coherent emission due to geomagnetic and charge-excess processes. These emissions can be observed in the frequency band between 10 - 100 MHz. However, this frequency range is significantly contaminated by narrow-band RFI and other human-made distortions. A FIR filter implemented in the FPGA logic segment of the front-end electronics of a radio sensor significantly improves the signal-to-noise ratio. In this paper we present first results of the efficiency of the adaptive LP FIR filter, deployed in real AERA station on pampas, with a comparison to the currently used IIR notch filter with constant coefficients. The laboratory tests confirms the stability of the filter. Using constant LP coefficients the suppression efficiency remains the same for hours, which corresponds to more than $\\bf 10^{12}$ clock cycles. We compared in real conditions several variants of the LP FIR filter with various lengths and various coefficients widths (due to fixed-point representations in the FPGA logic) with the aim to minimize the power consumption for the radio station while keeping sufficient accuracy for noise reduction.
CO Cameron band and CO2+ UV doublet emissions in the dayglow of Venus: Role of CO in the Cameron band production
NASA Astrophysics Data System (ADS)
Bhardwaj, Anil; Jain, Sonal Kumar
The present study deals with the model calculations of CO Cameron band and CO2+ ultraviolet doublet emissions in the dayglow of Venus. The overhead and limb intensities of CO Cameron band and CO2+ UV doublet emissions are calculated for low, moderate, and high solar activity conditions. Using updated cross sections, the impact of different e-CO cross sections for Cameron band production is estimated. The electron impact on CO is the major source mechanism of Cameron band, followed by electron and photon impact dissociation of CO2. The overhead intensities of CO Cameron band and CO2+UV doublet emissions are about a factor of 2 higher in solar maximum than those in solar minimum condition. The effect of solar EUV flux models on the emission intensity is ś30-40% in solar minimum condition and ś2-10% in solar maximum condition. At the altitude of emission peak (ś135 km), the model predicted limb intensity of CO Cameron band and CO2+ UV doublet emissions in moderate (F10.7=130) solar activity condition is about 2400 and 300 kR, respectively, which is in agreement with the very recently published SPICAV/Venus Express observation. The model limb intensity profiles of CO Cameron band and CO2+UV doublet are compared with SPICAV observation. We also calculated intensities of N2Vegard-Kaplan UV bands and O I 2972 ┼ emissions during moderate and high solar activity conditions.
Discovery of SiO Band Emission from Galactic B[e] Supergiants
NASA Astrophysics Data System (ADS)
Kraus, M.; Oksala, M. E.; Cidale, L. S.; Arias, M. L.; Torres, A. F.; Borges Fernandes, M.
B[e] supergiants (B[e]SGs) are evolved massive stars in a short-lived transition phase. During this phase, these objects eject large amounts of material, which accumulate in a circumstellar disk-like structure. The expelled material is typically dense and cool, providing the cradle for molecule and dust condensation and for a rich, ongoing chemistry. Very little is known about the chemical composition of these disks, beyond the emission from dust and CO revolving around the star on Keplerian orbits. As massive stars preserve an oxygen-rich surface composition throughout their life, other oxygen-based molecules can be expected to form. As SiO is the second most stable oxygen compound, we initiated an observing campaign to search for first-overtone SiO emission bands. We obtained high-resolution near-infrared L-band spectra for a sample of Galactic B[e]SGs with reported CO band emission. We clearly detect emission from the SiO first-overtone bands in CPD-52 9243 and indications for faint emission in HD 62623, HD 327083, and CPD-57 2874. From model fits, we find that in all these stars the SiO bands are rotationally broadened with a velocity lower than observed in the CO band forming regions, suggesting that SiO forms at larger distances from the star. Hence, searching for and analyzing these bands is crucial for studying the structure and kinematics of circumstellar disks, because they trace complementary regions to the CO band formation zone. Moreover, since SiO molecules are the building blocks for silicate dust, their study might provide insight in the early stage of dust formation. Based on observations collected with the ESO VLT Paranal Observatory under program 093.D-0248(A).
An optimization of the FPGA/NIOS adaptive FIR filter using linear prediction to reduce narrow band RFI for the next generation ground-based ultra-high energy cosmic-ray experiment
NASA Astrophysics Data System (ADS)
Szadkowski, Zbigniew; Fraenkel, E. D.; Glas, Dariusz; Legumina, Remigiusz
The electromagnetic part of an extensive air shower developing in the atmosphere provides significant information complementary to that obtained by water Cherenkov detectors which are predominantly sensitive to the muonic content of an air shower at ground. The emissions can be observed in the frequency band between 10 and 100 MHz. However, this frequency range is significantly contaminated by narrow-band RFI and other human-made distortions. The Auger Engineering Radio Array currently suppresses the RFI by multiple time-to-frequency domain conversions using an FFT procedure as well as by a set of manually chosen IIR notch filters in the time-domain. An alternative approach developed in this paper is an adaptive FIR filter based on linear prediction (LP). The coefficients for the linear predictor are dynamically refreshed and calculated in the virtual NIOS processor. The radio detector is an autonomous system installed on the Argentinean pampas and supplied from a solar panel. Powerful calculation capacity inside the FPGA is a factor. Power consumption versus the degree of effectiveness of the calculation inside the FPGA is a figure of merit to be minimized. Results show that the RFI contamination can be significantly suppressed by the LP FIR filter for 64 or less stages.
Improved efficiency of ternary the blend polymer solar cells by doping a narrow band gap polymer material
NASA Astrophysics Data System (ADS)
Zhu, XiXiang; An, QiaoShi; Huang, Hui; Jiao, ChaoQun; Zhang, FuJun
A series of P3HT:PC71BM polymer solar cells (PSCs) with different PIDTDTQx doping concentrations were fabricated to investigate the effect of the PIDTDTQx as a complementary electron donor on the performance of PSCs. The power conversion efficiency (PCE) of the optimized ternary blend PSCs (with 2 wt% PIDTDTQx) reached 3.87%, which is 28% higher than that of the PSCs based on P3HT:PC71BM (control cells). The short-circuit current density ( J sc) was increased to 10.20 mA/cm2 compared with the control cells. The PCE improvement could be attributed to more photon harvest and charge carrier transport by appropriate doping PIDTDTQx. The energy transfer from P3HT to PIDTDTQx was demonstrated from the 650 nm emission intensity decrease and the red-shifted emission peaks from 725 nm to 737 nm along with the increase of PIDTDTQx doping concentrations.
Scharwaechter, J.; Dopita, M. A. [Research School of Astronomy and Astrophysics, The Australian National University, Mount Stromlo Observatory, Cotter Road, Weston Creek 2611 (Australia); Zuther, J.; Fischer, S.; Eckart, A. [I. Physikalisches Institut, Universitaet zu Koeln, Zuelpicher Strasse 77, 50937 Koeln (Germany); Komossa, S., E-mail: firstname.lastname@example.com [Max-Planck-Institut fuer extraterrestrische Physik, Postfach 1312, 85741 Garching (Germany)
Extended narrow-line regions (ENLRs) and extended emission-line regions have been the focus of integral field spectroscopy aiming at the inner kiloparsecs of nearby Seyfert galaxies as well as the larger environment of high-redshift QSOs. Based on observations with the Wide Field Spectrograph at the 2.3 m telescope of the Australian National University, we present spatially resolved emission-line diagnostics of the bright Seyfert 1.5 galaxy HE 2211-3903 which is drawn from a sample of the brightest Seyfert galaxies at z < 0.06 with luminosities around the classical Seyfert/QSO demarcation. In addition to the previously known spiral arms of HE 2211-3903, the emission-line maps reveal a large-scale ring with a radius of about 6 kpc which is connected to the active galactic nucleus (AGN) through a bar-like structure. The overall gas kinematics indicates a disk rotation pattern. The emission-line ratios show Seyfert-type, H II region-type, and composite classifications, while there is no strong evidence of LINER-type ratios. Shock ionization is likely to be negligible throughout the galaxy. The composite line ratios are explained via a mixing line between AGN and H II region photoionization. Composite line ratios are predominantly found in between the H II regions in the circum-nuclear region, the bar-like structure to the east of the nucleus, and the eastern half of the ring, suggesting AGN photoionization of the low-density interstellar medium in an ENLR on galaxy scales. The line ratios in the nucleus indicate N enrichment, which is discussed in terms of chemical enrichment by Wolf-Rayet and asymptotic giant branch stars during past and ongoing nuclear starburst activity.
Broadband femtosecond OPCPA system driven by the single-shot narrow-band iodine photodissociation laser SOFIA
NASA Astrophysics Data System (ADS)
Novßk, O.; Tur?i?ovß, H.; Smr×, M.; Huynh, J.; Pfeifer, M.; Straka, P.
A two-stage optical parametric amplifier driven by a frequency-tripled beam from the high-energy iodine laser system SOFIA was built. This single-shot Optical Parametric Chirped Pulse-Amplification facility (OPCPA) and the system synchronizing the pump and signal pulses are described in detail. The chirped seed pulse of a Ti:sapphire oscillator running at the central wavelength of 800 nm is amplified in the two-stage (LBO and KDP) optical parametric amplifier over 108 times. The amplified spectral bandwidth of 68 nm corresponds to the pulse duration of 14 fs when a transform-limited pulse is assumed. This implies a compressed pulse of TW power. Systematic gain measurements reveal a good match with the theoretical predictions. Signal and idler beam fluence profiles are presented. The suitability of the iodine photo-dissociation laser as a pump source for the OPCPA technique is thus proved for the first time experimentally. A distinctive feature of the iodine laser is its very narrow gain bandwidth (<0.1 cm-1) and, therefore, the conventional chirped-pulse amplification technique does not lead to pulse durations at the femtosecond level.
Terahertz Emission from Narrow Gap Semiconductors Photoexcited by Femtosecond Laser Pulses
NASA Astrophysics Data System (ADS)
Adomavicius, R.; Urbanowicz, A.; Molis, G.; Krotkus, A.
Large increase in the emitted terahertz power was observed for p-InAs samples with the p-doping levels of approximately 1016-1017 cm-3. This increase was explained by a large surface depletion layer and an electric-field-induced optical rectification effect in the layer. Terahertz fields radiated by the samples of all three investigated CdxHg1-xTe layers was of the same order of magnitude. No azimuthal angle dependence of the radiated signal was detected, which evidences that linear current surge effect is dominating over nonlinear optical rectification. Azimuthal angle and magnetic fields emission witness that it is caused by linear photo-Dember type processes.
33 W quasi-continuous-wave narrow-band sodium D2a laser by sum-frequency generation in LBO
NASA Astrophysics Data System (ADS)
Wang, Peng-Yuan; Xie, Shi-Yong; Bo, Yong; Wang, Bao-Shan; Zuo, Jun-Wei; Wang, Zhi-Chao; Shen, Yu; Zhang, Feng-Feng; Wei, Kai; Jin, Kai; Xu, Yi-Ting; Xu, Jia-Lin; Peng, Qin-Jun; Zhang, Jing-Yuan; Lei, Wen-Qiang; Cui, Da-Fu; Zhang, Yu-Dong; Xu, Zu-Yan
We demonstrate an all-solid quasi-continuous-wave (QCW) narrow-band source tunable to sodium D2a line at 589.159 nm. The source is based on sum-frequency mixing between lasers at 1064 nm and 1319 nm in a LBO crystal. The 1064 nm and 1319 nm lasers are produced from two diode side-pumped Nd:YAG master oscillator power amplifier (MOPA) laser systems, respectively. A 33 W output of 589 nm laser is obtained with beam quality factor M2 = 1.25, frequency stability better than ▒0.2 GHz and linewidth less than 0.44 GHz. A prototype 589 nm laser system is assembled, and a sodium laser guided star has been successfully observed in the field test.
Variable-cavity-length mode-locked Nd:YAG laser for noncontact generation and spectral control of narrow-band ultrasound.
Deaton, J B; Wagner, J W
A passively mode-locked, flash-lamp-pumped long-cavity Nd:YAG laser was developed with a cavity length that was variable in discrete increments from approximately 11 to 60 m, permitting adjustment of the mode-locked pulse repetition frequency over a range from 13 to 2.5 MHz. Multiple-pulse acoustic signals were generated with this laser in an aluminum sample and remotely detected by a path-stabilized Michelson interferometer. The energy in the multiple-pulse acoustic signal was confined to a considerably reduced spectral range compared with that in a single pulse. Successful laser generation of spectrally selective narrow-band ultrasound presents new opportunities to integrate advanced signal-processing strategies with interferometric detection to enhance the sensitivity of laser ultrasonics for industrial applications. PMID:20862115
Origin of yellow-band emission in epitaxially grown GaN nanowire arrays.
Liu, Baodan; Yuan, Fang; Dierre, Benjamin; Sekiguchi, Takashi; Zhang, Song; Xu, Yongkuan; Jiang, Xin
Here, we report the origin of the yellow-band emission in epitaxial GaN nanowire arrays grown under carbon-free conditions. GaN nanowires directly grown on [0001]-oriented sapphire substrate exhibit an obvious and broad yellow-band in the visible range 400-800 nm, whereas the insertion of Al/Au layers in GaN-sapphire interface significantly depresses the visible emission, and only a sharp peak in the UV range (369 nm) can be observed. The persuasive differences in cathodoluminescence provide direct evidence for demonstrating that the origin of the yellow-band emission in GaN nanowire arrays arises from dislocation threading. The idea using buffering/barrier layers to isolate the dislocation threading in epitaxially grown GaN nanowires can be extended to the rational synthesis and structural defect controlling of a wide range of semiconductor films and nanostructures with superior crystal quality and excellent luminescence property. PMID:25057903
Yb5Ga2Sb6: a mixed valent and narrow-band gap material in the RE5M2X6 family.
Subbarao, Udumula; Sarkar, Sumanta; Gudelli, Vijay Kumar; Kanchana, V; Vaitheeswaran, G; Peter, Sebastian C
A new compound Yb5Ga2Sb6 was synthesized by the metal flux technique as well as high frequency induction heating. Yb5Ga2Sb6 crystallizes in the orthorhombic space group Pbam (no. 55), in the Ba5Al2Bi6 structure type, with a unit cell of a = 7.2769(2) ┼, b = 22.9102(5) ┼, c = 4.3984(14) ┼, and Z = 2. Yb5Ga2Sb6 has an anisotropic structure with infinite anionic double chains (Ga2Sb6)(10-) cross-linked by Yb(2+) and Yb(3+) ions. Each single chain is made of corner-sharing GaSb4 tetrahedra. Two such chains are bridged by Sb2 groups to form double chains of 1/? [Ga2Sb6(10-)]. The compound satisfies the classical Zintl-Klemm concept and is a narrow band gap semiconductor with an energy gap of around 0.36 eV calculated from the electrical resistivity data corroborating with the experimental absorption studies in the IR region (0.3 eV). Magnetic measurements suggest Yb atoms in Yb5Ga2Sb6 exist in the mixed valent state. Temperature dependent magnetic susceptibility data follows the Curie-Weiss behavior above 100 K and no magnetic ordering was observed down to 2 K. Experiments are accompanied by all electron full-potential linear augmented plane wave (FP-LAPW) calculations based on density functional theory to calculate the electronic structure and density of states. The calculated band structure shows a weak overlap of valence band and conduction band resulting in a pseudo gap in the density of states revealing semimetallic character. PMID:24224906
Compact high-quality CdSe/CdS core/shell nanocrystals with narrow emission linewidths and suppressed blinking
Chen, Ou; Zhao, Jing; Chauhan, Vikash P.; Cui, Jian; Wong, Cliff; Harris, Daniel K.; Wei, He; Han, Hee-Sun; Fukumura, Dai; Jain, Rakesh K.; Bawendi, Moungi G.
High particle uniformity, high photoluminescence quantum yields, narrow and symmetric emission spectral lineshapes and minimal single dot emission intermittency (known as blinking) have been recognized as universal requirements for the successful use of colloidal quantum dots (QDs) in nearly all optical applications. However, synthesizing samples that simultaneously meet all these four criteria has proven challenging. Here, we report the synthesis of such high-quality CdSe/CdS core/shell QDs in an optimized process which maintains a slow growth rate of the shell through the use of octanethiol and cadmium oleate as precursors. In contrast with previous observations, single-QD blinking is significantly suppressed with only a relatively thin shell. In addition, we demonstrate the elimination of the ensemble luminescence photodarkening that is an intrinsic consequence of QD blinking statistical aging. Furthermore, the small size and high photoluminescence quantum yields of these novel QDs render them superior in vivo imaging agents compared to conventional QDs. We anticipate that this new generation of QDs will also result in significant improvement in the performance of QDs in other applications such as solid-state lighting and illumination. PMID:23377294
Design and properties of intermediate-sized narrow band-gap conjugated molecules relevant to solution-processed organic solar cells.
Liu, Xiaofeng; Sun, Yanming; Hsu, Ben B Y; Lorbach, Andreas; Qi, Li; Heeger, Alan J; Bazan, Guillermo C
Increases in the molecular length of narrow band gap conjugated chromophores reveal potentially beneficial optical and electronic properties, thermal stabilities, and high power conversion efficiencies when integrated into optoelectronic devices, such as bulk heterojunction organic solar cells. With the objective of providing useful information for understanding the transition from small-sized molecules to polymers, as well as providing a general chemical design platform for extracting relationships between molecular structure and bulk properties, we set out to vary the electron affinity of the molecular backbone. Therefore, a series of donor (D)-acceptor (A) alternating narrow band gap conjugated chromophores were synthesized based on the general molecular frameworks: D(1)-A(1)-D(2)-A(2)-D(2)-A(1)-D(1) and D(1)-A(1)-D(2)-A(2)-D(2)-A(2)-D(2)-A(1)-D(1). When the central electron-accepting moiety (A(2)) was varied or modified, two classes of molecules could be compared. First, we showed that the alteration of one single electron-accepting group, while maintaining the shape of the molecular framework, can effectively impact the optical properties and energy levels of the molecules. DFT ground state structure optimizations show similar "U" shape conformations among these molecules. Second, we examined how the site-specific introduction of fluorine atom(s) modifies the thermal properties in the solid state, while maintaining relatively similar optical and electrochemical features of interest. Structure-property relationship of such molecular systems could be rationally evaluated in the aspects of thermal-responsive molecular organizations in the solid state and dipole moments both in the ground and excited states. The impact of molecular structure on charge carrier mobilities in field effect transistors and the performance of photovoltaic devices were also studied. PMID:24655075
Spontaneous Emission Alteration Near the One-Dimensional Photonic Band Edge of Semiconductor Heterostructures
Michael David Tocci
The alteration of the spontaneous emission of GaAs from within a photonic band gap structure is described and experimentally demonstrated. GaAs is used as an emitting layer in a typical p-i-n light emitting diode, and AlGaAs and AlAs are used in an alternating sequence on either side of the emitting layer to form a photonic band gap structure. The thickness
Bulk band gaps in divalent hexaborides: A soft x-ray emission study
Denlinger, Jonathan D.; Gweon, Gey-Hong; Allen, James W.; Bianchi, Andrea D.; Fisk, Zachary
Boron K-edge soft x-ray emission and absorption are used to address the fundamental question of whether divalent hexaborides are intrinsic semimetals or defect-doped bandgap insulators. These bulk sensitive measurements, complementary and consistent with surface-sensitive angle-resolved photoemission experiments, confirm the existence of a bulk band gap and the location of the chemical potential at the bottom of the conduction band.
Time-resolved spectroscopy of the visible emission band in strontium titanate
R. Leonelli; J. L. Brebner
The luminescence spectrum of SrTiO3 from 1.6 to 3.2 eV has been studied as a function of time elapsed after excitation. A broad emission band with maximum intensity at 2.44 eV can be observed. The shape of this band, including some fine structure, can be reproduced by the Huang-Rhys model for excitation-lattice interaction. A vibron energy hOmega=88 meV and a
Ocean Surface Emissivity at L-band (1.4 GHz): The Dependence on Salinity and Roughness
NASA Technical Reports Server (NTRS)
LeVine, D. M.; Lang, R.; Wentz, F.; Messiner, T.
A characterization of the emissivity of sea water at L-band is important for the remote sensing of sea surface salinity. Measurements of salinity are currently being made in the radio astronomy band at 1.413 GHz by ESA's Soil Moisture and Ocean Salinity (SMOS) mission and NASA's Aquarius instrument aboard the Aquarius/SAC-D observatory. The goal of both missions is accuracy on the order of 0.1 psu. This requires accurate knowledge of the dielectric constant of sea water as a function of salinity and temperature and also the effect of waves (roughness). The former determines the emissivity of an ideal (i.e. flat) surface and the later is the major source of error from predictions based on a flat surface. These two aspects of the problem of characterizing the emissivity are being addressed in the context of the Aquarius mission. First, laboratory measurements are being made of the dielectric constant of sea water. This is being done at the George Washington University using a resonant cavity. In this technique, sea water of known salinity and temperature is fed into the cavity along its axis through a narrow tube. The sea water changes the resonant frequency and Q of the cavity which, if the sample is small enough, can be related to the dielectric constant of the sample. An extensive set of measurements have been conducted at 1.413 GHz to develop a model for the real and imaginary part of the dielectric constant as a function of salinity and temperature. The results are compared to the predictions of models based on parameterization of the Debye resonance of the water molecule. The models and measurements are close; however, the differences are significant for remote sensing of salinity. This is especially true at low temperatures where the sensitivity to salinity is lowest.
Spontaneous emission from a two-level atom in two-band anisotropic photonic crystals
Yang Yaping [Department of Physics, Tongji University, Shanghai 200092 (China); Fachbereich Physik, University Kaiserslautern, D-67663 Kaiserslautern (Germany); Department of Physics, Hongkong Baptist University, Hong Kong (China); Fleischhauer, M. [Fachbereich Physik, University Kaiserslautern, D-67663 Kaiserslautern (Germany); Zhu Shiyao [Department of Physics, Hongkong Baptist University, Hong Kong (China)
We investigate the spontaneous radiation from a two-level atom embedded in a three-dimensional anisotropic photonic crystal with two bands. The properties of the spontaneous emission are dependent strongly on the position of the upper level. The faster and slower decay components can occur in the emitted field, but it does not mean the existence of both accelerated and inhibited components for the atomic population decay. The radiation spectrum is dependent on the location of the observer. We also study the influence of the existence of the two bands on spontaneous emission, Lamb shift, the emitted field, and the radiation spectrum.
Predicting Thaumastocoris peregrinus damage using narrow band normalized indices and hyperspectral indices using field spectra resampled to the Hyperion sensor
NASA Astrophysics Data System (ADS)
Oumar, Z.; Mutanga, O.; Ismail, R.
Thaumastocoris peregrinus (T. peregrinus) is a sap sucking insect that feeds on Eucalyptus leaves. It poses a threat to the forest industry by reducing the photosynthetic ability of the tree, resulting in stunted growth and even death of severely infested trees. Remote sensing techniques offer the potential to detect and map T. peregrinus infestations in plantation forests using current operational hyperspectral scanners. This study resampled field spectral data measured from a field spectrometer to the band settings of the Hyperion sensor in order to assess its potential in predicting T. peregrinus damage. Normalized indices based on NDVI ratios were calculated using the resampled visible and near-infrared bands of the Hyperion sensor to assess its utility in predicting T. peregrinus damage using Partial Least Squares (PLS) regression. The top 20 normalized indices were based on specific biochemical absorption features that predicted T. peregrinus damage with a mean bootstrapped R2 value of 0.63 on an independent test dataset. The top 20 indices were located in the near-infrared region between 803.3 nm and 894.9 nm. Twenty three previously published hyperspectral indices which have been used to assess stress in vegetation were also used to predict T. peregrinus damage and resulted in a mean bootstrapped R2 value of 0.59 on an independent test dataset. The datasets were combined to assess its collective strength in predicting T. peregrinus damage and significant indices were chosen based on variable importance scores (VIP) and were then entered into a PLS model. The indices chosen by VIP predicted T. peregrinus damage with a mean bootstrapped R2 value of 0.71 on an independent test dataset. A greedy backward variable selection model was further tested on the VIP selected indices in order to find the best subset of indices with the best predictive accuracy. The greedy backward variable selection model identified 3 indices and performed the best by predicting damage with an R2 value of 0.74 with the lowest RMSE of 1.30% on an independent test dataset. The best three indices identified include the anthocyanin reflectance index, carotenoid reflectance index and the normalized index calculated at 864.4 and 884.7 nm. Individual relationships between these indices and T. peregrinus damage indicate that high correlations are obtained with the inclusion of a few severely infested trees in the sample size. When the severely infested trees were removed from the study, the normalized index (864.4 and 884.7 nm) and the anthocyanin reflectance index still yielded significant correlations at the 99% confidence interval. This study indicates the significance of normalized indices and spectral indices calculated from the visible and near-infrared bands in hyperspectral data for the prediction of T. peregrinus damage.
Detecting long-duration narrow-band gravitational wave transients associated with soft gamma repeater quasiperiodic oscillations
NASA Astrophysics Data System (ADS)
Murphy, David; Tse, Maggie; Raffai, Peter; Bartos, Imre; Khan, Rubab; Mßrka, Zsuzsa; Matone, Luca; Redwine, Keith; Mßrka, Szabolcs
We have performed an in-depth concept study of a gravitational wave data analysis method which targets repeated long quasimonochromatic transients (triggers) from cosmic sources. The algorithm concept can be applied to multitrigger data sets in which the detector-source orientation and the statistical properties of the data stream change with time, and does not require the assumption that the data is Gaussian. Reconstructing or limiting the energetics of potential gravitational wave emissions associated with quasiperiodic oscillations observed in the x-ray lightcurve tails of soft gamma repeater flares might be an interesting endeavor of the future. Therefore we chose this in a simplified form to illustrate the flow, capabilities, and performance of the method. We investigate performance aspects of a multitrigger based data analysis approach by using O(100s) long stretches of mock data in coincidence with the times of observed quasiperiodic oscillations, and by using the known sky location of the source. We analytically derive the probability density function of the background distribution and compare to the results obtained by applying the concept to simulated Gaussian noise, as well as off-source playground data collected by the 4-km Hanford detector during LIGOÆs fifth science run (S5). We show that the transient glitch rejection and adaptive differential energy comparison methods we apply succeed in rejecting outliers in the fifth science run background data. Finally, we discuss how to extend the method to a network containing multiple detectors, and as an example, tune the method to maximize sensitivity to soft gamma repeater 1806-20 flare times.
Technology Transfer Automated Retrieval System (TEKTRAN)
Dew has the net effect of decreasing the brightness temperature of maize at L-band. Scattering is enhanced more than emission. This effect occurs at both polarizations, but vertically-polarized brightness is affected more than horizontally-polarized brightness. As more water condenses on the cano...
L-band emission of rough surfaces: Comparison between experimental data and different modeling approaches
Heather Lawrence; Franńois Demontoux; Jean-Pierre Wigneron; Arnaud Mialon; Tzong-Dar Wu; Valery Mironov; Liang Chen; Jianchen Shi; Yann Kerr
In this paper we present a study of a numerical modeling approach based on the Finite Element Method (FEM) for the prediction of rough surface emission at L-band, including a comparison with other modeling approaches and experimental data. The numerical approach relies on the use of ANSYS' numerical computation software HFSS (High Frequency Structure Simulator), which in turn solves Maxwell's
Extended red emission and unidentified infrared bands in the galactic compact H II region Sh 152
NASA Astrophysics Data System (ADS)
Darbon, S.; Zavagno, A.; Perrin, J.-M.; Savine, C.; Ducci, V.; Sivan, J.-P.
We present visible and infrared images and low-dispersion visible spectra of the galactic compact H Ii region Sh 152. The spatial distribution of the Extended Red Emission (ERE) over the nebula is found to coincide with that of the ionized hydrogen emission and to differ from that of the Unidentified InfraRed Bands (UIRBs) emission at 3.3 and 6.2 mu m. This result and other considerations are in favour of grains as carriers of the ERE. It is shown that nanosized silicon particles could account for the ERE in terms of luminescence, an interpretation which, however, suffers from some limitations.
Effect of focal spot size on in-band 13.5 nm extreme ultraviolet emission from laser-produced
Najmabadi, Farrokh
Effect of focal spot size on in-band 13.5 nm extreme ultraviolet emission from laser-produced Sn spot size on in-band 13.5 nm extreme ultraviolet (EUV) emission from laser-produced Sn plasmas was confirmed by a dip located at 13.5 nm in the spectrum. ® 2006 Optical Society of America OCIS codes: 350
Results and lessons from MODIS thermal emissive bands calibration: pre-launch to on-orbit
NASA Astrophysics Data System (ADS)
Xiong, X.; Chiang, K.; Chen, N.; Xiong, S.; Barnes, W. L.; Guenther, B.
The Moderate Resolution Imaging Spectroradiometer (MODIS) is a major instrument for NASA's Earth Observing System (EOS), currently operating on-board the EOS Terra spacecraft, launched in December 1999, and Aqua spacecraft, launched in May 2002. MODIS is a whiskbroom scanning radiometer using a double-sided paddle wheel scan mirror. It makes measurements in 36 spectral bands with wavelengths from visible (VIS) to long-wave infrared (LWIR). Bands 20-25 and 27-36 are the thermal emissive bands (TEB) covering wavelengths from 3.5 to 14.4?m. During pre-launch thermal vacuum measurements, a laboratory blackbody calibration source (BCS) was used as the primary calibration source for the TEB. For on-orbit operation, an on-board blackbody (BB) source and a space view (SV) port are used together for the TEB calibration on a scan-by-scan basis. This paper provides an overview of Terra and Aqua MODIS pre-launch and on-orbit calibration and characterization activities, methodologies, data analysis results, and lessons learned for the thermal emissive bands. It focuses on major issues that could impact MODIS TEB calibration and data quality. Results presented in this paper include detector noise characterization, response versus scan angle (RVS), and response versus instrument and focal plane temperatures. Similar discussions for the MODIS reflective solar bands (RSB) are presented in a separate paper in these proceedings (Xiong et. al).
GROUND-BASED DETECTIONS OF THERMAL EMISSION FROM THE DENSE HOT JUPITER WASP-43b IN THE H AND K{sub s} BANDS
Wang, W.; Zhao, G. [Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China); Van Boekel, R.; Henning, Th. [Max Planck Institute for Astronomy, Koenigstuhl 17, D-69117 Heidelberg (Germany); Madhusudhan, N. [Department of Physics and Department of Astronomy, Yale University, New Haven, CT 06511 (United States); Chen, G., E-mail: email@example.com [Purple Mountain Observatory, Chinese Academy of Sciences, West Beijing Road, Nanjing 210008 (China)
We report new detections of thermal emission from the transiting hot Jupiter WASP-43b in the H and K{sub s} bands as observed at secondary eclipses. The observations were made with the WIRCam instrument on the Canada-France-Hawaii Telescope. We obtained a secondary eclipse depth of 0.103{sub -0.017}{sup +0.017}%$ and 0.194{sub -0.029}{sup +0.029} in the H and K{sub s} bands, respectively. The K{sub s}-band depth is consistent with the previous measurement in the narrow band centered at 2.09 {mu}m by Gillon et al. Our eclipse depths in both bands are consistent with a blackbody spectrum with a temperature of {approx}1850 K, slightly higher than the dayside equilibrium temperature without day-night energy redistribution. Based on theoretical models of the dayside atmosphere of WASP-43b, our data constrain the day-night energy redistribution in the planet to be {approx}< 15%-25%, depending on the metal content in the atmosphere. Combined with energy balance arguments, our data suggest that a strong temperature inversion is unlikely in the dayside atmosphere of WASP-43b. However, a weak inversion cannot be strictly ruled out at the current time. Future observations are required to place detailed constraints on the chemical composition of the atmosphere.
Clicking in a Killer Whale Habitat: Narrow-Band, High-Frequency Biosonar Clicks of Harbour Porpoise (Phocoena phocoena) and DallÆs Porpoise (Phocoenoides dalli)
Kyhn, Line A.; Tougaard, Jakob; Beedholm, Kristian; Jensen, Frants H.; Ashe, Erin; Williams, Rob; Madsen, Peter T.
Odontocetes produce a range of different echolocation clicks but four groups in different families have converged on producing the same stereotyped narrow band high frequency (NBHF) click. In microchiropteran bats, sympatric species have evolved the use of different acoustic niches and subtly different echolocation signals to avoid competition among species. In this study, we examined whether similar adaptations are at play among sympatric porpoise species that use NBHF echolocation clicks. We used a six-element hydrophone array to record harbour and DallÆs porpoises in British Columbia (BC), Canada, and harbour porpoises in Denmark. The click source properties of all porpoise groups were remarkably similar and had an average directivity index of 25 dB. Yet there was a small, but consistent and significant 4 kHz difference in centroid frequency between sympatric DallÆs (137▒3 kHz) and Canadian harbour porpoises (141▒2 kHz). Danish harbour porpoise clicks (136▒3 kHz) were more similar to DallÆs porpoise than to their conspecifics in Canada. We suggest that the spectral differences in echolocation clicks between the sympatric porpoises are consistent with evolution of a prezygotic isolating barrier (i.e., character displacement) to avoid hybridization of sympatric species. In practical terms, these spectral differences have immediate application to passive acoustic monitoring. PMID:23723996
Feeding at a high pitch: source parameters of narrow band, high-frequency clicks from echolocating off-shore hourglass dolphins and coastal Hector's dolphins.
Kyhn, Line A; Tougaard, J; Jensen, F; Wahlberg, M; Stone, G; Yoshinaga, A; Beedholm, K; Madsen, P T
Toothed whales depend on echolocation for orientation and prey localization, and source parameters of echolocation clicks from free-ranging animals therefore convey valuable information about the acoustic physiology and behavioral ecology of the recorded species. Recordings of wild hourglass (Lagenorhynchus cruciger) and Hector's dolphins (Cephalorhynchus hectori) were made in the Drake Passage (between Tierra del Fuego and the Antarctic Peninsular) and Banks Peninsular (Akaroa Harbour, New Zealand) with a four element hydrophone array. Analysis of source parameters shows that both species produce narrow band high-frequency (NBHF) echolocation clicks. Coastal Hector's dolphins produce clicks with a mean peak frequency of 129 kHz, 3 dB bandwidth of 20 kHz, 57 micros, 10 dB duration, and mean apparent source level (ASL) of 177 dB re 1 microPa(p.-p.). The oceanic hourglass dolphins produce clicks with mean peak frequency of 126 kHz, 3 dB bandwidth of 8 kHz, 116 micros, 10 dB duration, and a mean estimated ASL of 197 dB re 1 microPa(p.-p.). Thus, hourglass dolphins apparently produce clicks of higher source level, which should allow them to detect prey at more than twice the distance compared to Hector's dolphins. The observed source parameter differences within these two NBHF species may be an adaptation to a coastal cluttered environment versus a deep water, pelagic habitat. PMID:19275335
Absorption of monochromatic and narrow band radiation in the visible and near IR by both mitochondrial and non-mitochondrial photoacceptors results in photobiomodulation.
Passarella, Salvatore; Karu, Tiina
In addition to the major functions performed by in the cell, mitochondria play a major role in cell-light interaction. Accordingly it is generally accepted that mitochondria are crucial in cell photobiomodulation; however a variety of biomolecules themselves proved to be targets of light irradiation. We describe whether and how mitochondria can interact with monochromatic and narrow band radiation in the red and near IR optical regions with dissection of both structural and functional effects likely leading to photobiostimulation. Moreover we also report that a variety of biomolecules localized in mitochondria and/or in other cell compartments including cytochrome c oxidase, some proteins, nucleic acids and adenine nucleotides are light sensitive with major modifications in their biochemistry. All together the reported investigations show that the elucidation of the mechanism of the light interaction with biological targets still remains to be completed, this needing further research, however the light sensitivity of a variety of molecules strongly suggests that photobiomodulation could be used in both in photomedicine and in biotechnology. PMID:25226343
A space-borne fiber-optic interrogator module based on narrow-band tunable laser diode for temperature monitoring in telecommunication satellites
NASA Astrophysics Data System (ADS)
Putzer, P.; Kuhenuri, N.; Koch, A. W.; Schweyer, S.; Hurni, A.; Plattner, M.
In this paper measurement results of the fiber-optic interrogator module for telecommunication satellite applications are presented. The sensor interrogator features from fiber Bragg grating (FBG) based sensing. Benefits are intrinsic sensor distribution capability and the possibility to embed optical fibers in composite structures like tanks and satellite panels. The fiber-optic interrogator module is based on a narrow-band monolithic laser diode where the output wavelength is spectrally tuned by electric control signals. By evaluating the intensities of the sensor response, the peak of the FBG can be monitored. The correct evaluation of the sensor response is a challenging task, therefore different computational methods are presented, namely centroid, finite impulse response filter and curve fitting algorithms. The algorithms shall met the performance requirements in terms of measurement accuracy, robustness against laser degradation and measurement rate. Furthermore the algorithms shall be implemented in an FPGA, which means a detailed point of view to fixed-point arithmetic and necessary amount of hardware resources at constant performance. Measurement results based on the different FBG evaluation algorithms are presented and traded regarding accuracy robustness and their possible implementation in an FPGA.
Effect of Narrow Band Ultraviolet B Therapy versus Methotrexate on Serum Levels of Interleukin-17 and Interleukin-23 in Egyptian Patients with Severe Psoriasis
Elghandour, Tarek Mahmoud; Youssef, Sahar El Sayed; Aly, Dalia Gamal; Abd Elhameed, Mohamed Said; Abdel Moneim, Mehrevan Mostafa
Background. There is raised interest in the involvement of interleukin-(IL-)23/T-helper 17 cells (Th17) axis in the pathogenesis of psoriasis. Objectives. To compare the effect of narrow band ultraviolet B (NB-UVB) and methotrexate (MTX) therapy on serum levels of IL-17 and IL-23 in psoriatic patients. Methods. Thirty patients with severe plaque psoriasis were included: 15 patients received NB-UVB three times weekly (group I) and 15 patients received MTX 0.3?mg/kg per week (group II), both for 8 weeks. Before and after treatment, serum levels of IL-17 and IL-23 were investigated by ELISA technique and psoriasis area and severity index (PASI) was calculated. Results. After treatment, all patients showed a reduction in their PASI score, IL-17 and IL-23 serum levels with a nonsignificant difference between both therapeutic modalities (P value >0.05). A positive correlation was detected between the percent of reduction of IL-17, IL-23 and the percent of reduction of PASI score for patients receiving both treatments. No correlation was found between the percent of reduction of IL-17, IL-23 and duration of disease or age of all patients in this study. Conclusion. Interleukin-17 and IL-23 serum level may serve as a potential biomarker for predicting the prognosis and therapeutic response of NB-UVB or MTX in treating psoriasis. PMID:24489536
Review of Terra MODIS thermal emissive band L1B radiometric performance
NASA Astrophysics Data System (ADS)
Moeller, Chris; Menzel, W. P.; Quinn, Greg
The MODerate-resolution Imaging Spectroradiometer (MODIS) on NASA's Earth Observing System Terra satellite, launched into orbit on 18 December 1999, will have a "first light" 15th anniversary on 24 February 2015. For nearly 15 years the MODIS instrument has provided radiances in all spectral bands. Though some detectors have fallen below SNR thresholds, the vast majority of spectral bands continue to provide high quality L1B measurements for use in L2 science algorithms supporting global climate research. Radiometric accuracy of the Terra MODIS thermal emissive bands (TEBs) in the C6 L1B product has been assessed using various approaches over the nearly 15 year Terra MODIS data record, including comparisons with instruments on the ground, in aircraft under-flights, and on other satellites. All of these approaches contribute to the understanding of the Terra MODIS radiometric L1B performance. Early in the lifetime of Terra, ground-based measurements and NASA ER-2 aircraft under-flights revealed that TEBs in the infrared window ("window" bands) are well calibrated and performing within accuracy specifications. The ER-2 under-flights also suggested that many atmospheric bands may be performing outside of specification, especially LWIR CO2 sensitive bands that are subject to optical crosstalk, although analysis uncertainties are larger for atmospheric bands. Beginning in 2007, MetOp-A IASI observations were used to evaluate Terra MODIS TEB performance through Simultaneous Nadir Overpass (SNO) comparisons. These inter-satellite comparisons largely affirm the early aircraft and ground-based evaluations, showing that all Terra MODIS window bands have small biases, minimal trending, and minor detector and mirror side striping over the 2007-2013 timeframe. Most atmospheric bands are performing satisfactorily near to specification; however, biases, striping and trending are large and significantly out of specification in the water vapor sensitive band 27 and ozone sensitive band 30 while the CO2 sensitive band 36 bias significantly exceeds specification. The investigation has found that an effective spectral shift significantly reduces biases and scene temperature dependence (but not trends) in most atmospheric bands, bringing them closer to, if not within, specification.
Generation and Propagation Characteristics of Dual-Band Chorus Emissions Observed by Geotail
NASA Astrophysics Data System (ADS)
Yagitani, S.; Habagishi, T.; Mori, S.; Omura, Y.; Kojima, H.
We analyze the generation and propagation characteristics of chorus emissions observed by the wave form capture (WFC) and the sweep frequency analyzer (SFA) onboard the Geotail spacecraft in the dayside outer magnetosphere (L from 9 to 10). We examine any observational evidence, which may validate the nonlinear growth theory of the chorus emissions [1]. In the nonlinear growth theory a rising-tone element is initially generated continuously in the frequency range from 0.1 to 0.7 fce, where fce is the gyrofrequency in the generation region. Because of the nonlinear damping mechanism the rising-tone element is separated into upper and lower bands at half the local gyrofrequency (1/2 fce) through propagation [2]. As the rising-tone emissions are generated in the minimum-B region and propagate toward the larger-B regions along the geomagnetic field line, the upper cutoff of the lower-band chorus corresponds to 1/2 fce in the generation region, and the lower cutoff of the upper-band chorus corresponds to 1/2 fce at the observation point. In this study, we analyze the SFA spectrum data (consecutively over several hours) and WFC waveform data (several seconds) of the dual-band chorus emissions observed by Geotail. As a result, it is found that the upper cutoff of the lower-band chorus coincides with 1/2 fce at the minimum-B region estimated from the geomagnetic field line connecting to the Geotail position by using the Tsyganenko geomagnetic field model (TS04 model), whereas the lower cutoff of the upper-band chorus coincides with 1/2 fce locally at the observation point. We also examine the amplitude of a rising-tone emission using the WFC waveform data on the basis of the nonlinear growth theory. The amplitude at the generation region is estimated from the observed frequency sweep rate of the emission, and the nonlinear growth of the amplitude through propagation toward the observation point is calculated from the nonlinear growth rate, which is found consistent with the observed amplitude. We will also discuss the observational evidence for the threshold amplitudes and the optimum amplitudes required for triggering rising-tone chorus emissions in the generation region. [1] Omura Y., Y. Katoh and D. Summers (2008), Theory and simulation of the generation of whistler-mode chorus, J. Geophys. Res., 113, A04223, doi:10.1029/2007JA012622. [2] Omura Y., M. Hikishima, Y. Katoh, D. Summers, and S. Yagitani (2009), Nonlinear mechanisms of lower-band and upper-band VLF chorus emissions in the magnetosphere, J.Geophys. Res., 114, A07217, doi:10.1029/2009JA014206. [3] Omura Y., and D. Nunn (2011), Triggering process of whistler mode chorus emissions in the magnetosphere, J. Geophys. Res., 116, A05205, doi:10.1029/2010JA016280.
BroadBand Spectrum of dMe Star Radio Emission M Gudel and A. O. Benz
Guedel, Manuel
Broad┬ŁBand Spectrum of dMe Star Radio Emission M G┬©udel and A. O. Benz Institute of Astronomy, ETH, Z┬©urich Running title: Spectrum of dMe Star Radio Emission Proofs and offprint requests: M. G.59.1 Journal: Letters #12; Broad┬ŁBand Spectrum of dMe Star Radio Emission M. G┬©udel and A.O. Benz Institute
VIIRS thermal emissive bands on-orbit calibration coefficient performance using vicarious calibration results
NASA Astrophysics Data System (ADS)
Moyer, D.; Moeller, C.; De Luccia, F.
The Visible Infrared Imager Radiometer Suite (VIIRS), a primary sensor on-board the Suomi-National Polar-orbiting Partnership (SNPP) spacecraft, was launched October 28, 2011. It has 22 bands: 7 thermal emissive bands (TEBs), 14 reflective solar bands (RSBs) and a Day Night Band (DNB). The TEBs cover the spectral wavelengths between 3.7 to 12 ?m and have two 371 m and five 742 m spatial resolution bands. A VIIRS Key Performance Parameter (KPP) is the sea surface temperature (SST) which uses bands M12 (3.7 ?m), M15 (10.8 ?m) and M16's (12.0 ?m) calibrated Science Data Records (SDRs). The TEB SDRs rely on pre-launch calibration coefficients used in a quadratic algorithm to convert the detector's response to calibrated radiance. This paper will evaluate the performance of these prelaunch calibration coefficients using vicarious calibration information from the Cross-track Infrared Sounder (CrIS) also onboard the SNPP spacecraft and the Infrared Atmospheric Sounding Interferometer (IASI) on-board the Meteorological Operational (MetOp) satellite. Changes to the pre-launch calibration coefficients' offset term c0 to improve the SDR's performance at cold scene temperatures will also be discussed.
Of narrow lines and beaming in the strong-field SSC emission model. [synchrotron self-Compton for gamma ray bursts
NASA Technical Reports Server (NTRS)
Preece, Robert D.
The synchrotron self-Compton (SSC) emission model for gamma-ray bursts is capable of producing narrow line features for a variety of modelled field strengths, primary electron injection distributions and burst luminosities. Multiple resonant scattering with synchrotron continuum photons efficiently traps and cools pairs in the ground state to an average energy where the Compton energy loss rate is zero. Annihilation between pairs in these cooled distributions can be very efficient. For isotropic injection of primary electrons, there is an anti-correlation of the intensity of the angular-binned emission between the portions of the continuum spectrum below the cyclotron peak and above the annihilation line feature. Small-angle emission dominates the continuum above the annihilation line feature and is smooth through the line up to the pair production cut-off, which can be above several MeV for small enough angles. The angle-averaged annihilation line is made of components which can have peak emission centered at energies away from 511 keV, due to Doppler shifting. For beamed injection,the annihilation line breaks up into relatively narrow components in the angular emission, which sum into a broad feature in the angle-averaged emission.
Energetic and Broad Band Spectral Distribution of Emission from Astronomical Jets
NASA Astrophysics Data System (ADS)
Pe'er, Asaf
Emission from astronomical jets extend over the entire spectral band: from radio to the TeV ?-rays. This implies that various radiative processes are taking place in different regions along jets. Understanding the origin of the emission is crucial in understanding the physical conditions inside jets, as well as basic physical questions such as jet launching mechanism, particle acceleration and jet composition. In this chapter I discuss various radiative mechanisms, focusing on jets in active galactic nuclei (AGN) and X-ray binaries (XRB) environment. I discuss various models in use in interpreting the data, and the insights they provide.
Nitric oxide delta band emission in the earth's atmosphere - Comparison of a measurement and a theory
NASA Technical Reports Server (NTRS)
Rusch, D. W.; Sharp, W. E.
Attention is given to the altitude dependent emission rate in the delta-bands of nitric oxide as measured in the earth's atmosphere at night by a scanning ultraviolet spectrometer. It is noted that the reaction responsible is the two-body association of nitrogen and oxygen atoms. The measurements show a vertical intensity beneath the layer for the delta-band system of 19 R. The horizontal emission rate is found to increase from 70 R at 117 km to 140 R at 150 km. The data are analyzed with a one-dimensional, time-dependent, vertical-transport model of odd nitrogen photochemistry. The calculated and measured intensities agree so long as the quenching of N(2D) by atomic oxygen is near 5 x 10 to the -13 cu cm/sec.
L to X-band scatter and emission measurements of vegetation
NASA Astrophysics Data System (ADS)
Hueppi, R.; Schanda, E.
A broad-band H and V polarization radiometer was combined with a noise transmitter to an instrument for measuring active and passive microwave signatures at seven frequencies between L and X band. This radiometer-scatterometer is operated from a cherry picker over agricultural fields. During the growing seasons the development of sugar-beet, wheat, and corn was measured. The geometrical structure of the vegetation cover was described by recording the crop type, the distances between the plants, and the canopy height. The soil underneath was characterized by moisture, temperature profile, and dielectric constant. Another variable was the seasonal change in water content of the plants. Relating these parameters to the microwave signatures reveals the interaction of scatter and emission processes between soil and vegetation. Significant differences of the emission and scattering behavior for the measured crops are found.
Valence band structure in boron-zinc oxide films characterized by secondary electron emission
NASA Astrophysics Data System (ADS)
Uhm, Han S.; Choi, Joon H.; Yoo, Ha J.; Kwon, Gi C.; Choi, Eun H.
Properties of the valence band structure in boron-zinc oxide (BZO) films were investigated using the secondary electron emission due to the Auger neutralization of helium ions, with respect to the application of BZO films to the development of solar cells, in which the conductivity of the BZO films plays a critical role in improving cell performance. The characteristic energy ?0 corresponding to the peak density of states in the valence band showed that BZO film prepared with a 3000 SCCM B2H6 gas flow rate (SCCM denotes cubic centimeters per minute at standard temperature and pressure) had a shallow characteristic energy ?0 = 5 eV, whereas film without boron doping had a deep characteristic energy ?0 = 8.2 eV, suggesting that a high concentration of boron impurity in BZO films might enhance the transition of electrons and holes through the bandgap from the valence to the conduction band in zinc oxide crystals, thereby improving the conductivity of the film. The measurement method developed here demonstrates that the secondary electron emission is very useful in the determination of the band structure in various synthetic films.
Bandwidths and amplitudes of chorus-like banded emissions measured by the TC-1 Double Star spacecraft
NASA Astrophysics Data System (ADS)
Mac·Üovß, E.; SantolĒk, O.; Cornilleau-Wehrlin, N.; Yearby, K. H.
Characteristics of banded whistler-mode emissions are derived from a database of chorus-like events obtained from the complete data set of the wave measurements provided by the Spatio-Temporal Analysis of Field Fluctuation-Digital Wave Processing (STAFF-DWP) wave instrument on board the TC-1 Double Star spacecraft. Our study covers the full operational period of this spacecraft (almost 4 years). Our entire data set has been collected within 30░ of geomagnetic latitude at L shells between 2 and 12 and below 4 kHz. All events have been processed automatically to accurately determine their power spectral density (PSD), bandwidth, and amplitude. We found most cases of chorus-like banded emissions at L?10 on the dawnside and dayside. The upper band emissions (above one half of the equatorial electron cyclotron frequency) occur almost 20 times less often than the lower band, and their average amplitude is almost 3 times smaller than for the lower band. Intense upper band emissions cover smaller L shell, magnetic local time (MLT), and magnetic latitudes regions than intense lower band emissions. The intense nightside and dawnside chorus-like banded emissions were observed at low magnetic latitudes, while the intense dayside and duskside emissions were mostly found at higher magnetic latitudes. The amplitudes of dayside lower band waves slightly increase as they propagate away from the geomagnetic equator and are smaller than chorus amplitudes on nightside and dawnside. The PSD, the amplitude of the lower band, its frequency bandwidth, and its occurrence rate significantly increase with increasing geomagnetic activity, while all these parameters for the upper band are not so strongly dependent on the geomagnetic activity.
Four emission bands from a mixed-ligand iridium complex IrQ(ppy)2 at room temperature
NASA Astrophysics Data System (ADS)
Tsuboi, Taiju; Huang, Duo-Fong; Chow, Tahsin J.; Huang, Wei
Four photoluminescence bands are observed from iridium complex in UV, violet, green, and red spectral regions at room temperature. Such a multiple emission is found from a mixed-ligand iridium(III) complex, (8-quinolinolato) bis(2-phenylpyridyl) iridium IrQ(ppy)2, which consists of IrQ and Ir(ppy)2 components (Q: 8-quinolinolato, ppy: phenylpyridyl). Of the four emission bands, the UV emission band with maximum at about 330 nm and the red emission band are attributed to the ligand-centered (1LC) 1n?* and metal-to-ligand charge transfer (3MLCT) 3(??*) states from IrQ, respectively, while the violet emission band with maximum at about 400 nm and the green emission band at about 513 nm are attributed to the 1LC 1(n?*) and 3MLCT 3??* states from Ir(ppy). It is suggested that (1) IrQ and Ir(ppy) generate their own emissions by the inefficient F÷rster energy transfer between IrQ and Ir(ppy) due to the orientation factor of nearly zero, and (2) each of IrQ and Ir(ppy) gives rise to two emissions from the singlet and triplet states by the inefficient intersystem crossing.
Effective optical identification of type ō0-IIbö early gastric cancer with narrow band imaging magnification endoscopy, successfully treated by endoscopic submucosal dissection
Eleftheriadis, Nikolas; Inoue, ?aruhiro; Ikeda, Haruo; Onimaru, Manabu; Yoshida, Akira; Maselli, Roberta; Santi, Grace; Hamatani, Shigeharu; Kudo, Shin-ei
Background Endoscopic submucosal dissection (ESD) is currently considered the minimal invasive endoscopic treatment for early gastric cancer. Most superficial gastric neoplastic lesions are depressed type ō0-IIcö (70-80%), while totally flat, classified as type ō0-IIbö early gastric cancer, is rarely reported (0.4%). The aim of the present study was to assess the efficacy of narrow band imaging (NBI) magnification endoscopy in identifying type ō0-IIbö early gastric cancer and ESD treatment with curative intention. Methods Twelve of 615 (2%) patients (10 males, median 72 years), treated by ESD at our center, were diagnosed as type ō0-IIbö gastric cancer. Ten had exclusively type ō0-IIbö, while two had combined types ō0-IIb+IIcö and ō0-IIa+IIbö gastric cancer. Initial diagnosis was made during screening gastroscopy, while NBI magnification endoscopy combined with indigo-carmine chromoendoscopy were also used. Results White light endoscopy showed only superficial redness. One patient with signet-ring carcinoma showed whitish appearance. Indigo-carmine chromoendoscopy showed better visualization, while NBI magnification endoscopy revealed abnormal mucosal microsurface and microvascular findings which enabled border marking. ESD with curative intention was completed without complications. Histological examination showed complete (R0) resection, in 10 patients (83%). One patient with positive margins received additional surgery (8%). Mean procedure time was 149 (range 60-190) min. One to six years post-ESD all patients remain alive. Conclusions ESD is considered a safe and effective curative treatment for type ō0-IIbö gastric cancer, resulting in long-term disease-free survival. NBI magnification endoscopy is effective for accurate optical identification and border marking of type ō0-IIbö early gastric cancer. PMID:25609014
Randomized Trial of Narrow-band Versus White-light Cystoscopy for Restaging (Second-look) Transurethral Resection of Bladder Tumors.
Herr, Harry W
Narrow-band imaging (NBI) cystoscopy detects more bladder tumors than standard white-light imaging (WLI) cystoscopy, but it is unclear whether NBI improves transurethral resection (TUR) of bladder tumors. This study compares 2-yr recurrence-free survival (RFS) of patients with non-muscle-invasive bladder tumors following restaging TUR using NBI or WLI cystoscopy. Patients were randomized 1:1 to undergo NBI-assisted TUR (NBI-TUR) or WLI-assisted TUR (WLI-TUR). The main outcome was number of patients free of tumor recurrence after 2-yr follow-up and 2-yr RFS times. Of 254 patients, 127 underwent NBI-TUR and 127 had WLI-TUR. Within 2 yr, 22% of the patients in the NBI-TUR group recurred compared with 33% after WLI-TUR (p=0.05). The mean RFS time was 22 mo (95% confidence interval [CI], 20-23) for the NBI-TUR group versus 19 mo (95% CI, 18-21) for the WLI-TUR group (p=0.02). Limitations are that this was a single-surgeon study and that a 20% difference in the number of patients free of recurrence was not achieved, suggesting the study was underpowered. In addition, observer bias may have contributed to results because NBI-TUR was performed after both WLI and NBI cystoscopy was used to inspect the bladder. Although the results suggest reduced recurrence rates and improved RFS times after restaging NBI-TUR compared with WLI-TUR, a larger study is needed. PMID:25041849
An educational intervention to improve the endoscopistÆs ability to correctly diagnose small gastric lesions using magnifying endoscopy with narrow-band imaging
Mabe, Katsuhiro; Yao, Kenshi; Nojima, Masanori; Tanuma, Tokuma; Kato, Mototsugu
Background Magnifying endoscopy with narrow-band imaging (ME-NBI) and a simple and systematic classification system based on microvascular and microsurface patterns, the ōVSö classification system (VSCS), have been shown to be useful for the diagnosis of early gastric cancer. The aim of this study was to clarify whether an educational lecture about the VSCS improves performance with ME-NBI. Methods Sixty-four gastrointestinal endoscopists took the 1st exam before receiving the lecture about the VSCS, the 2nd exam immediately after the lecture, and the 3rd exam 2 months after the lecture. We compared the VSCS-based diagnostic accuracy among the participants before and after the lecture. Results The proportion of correct diagnoses was significantly higher, at 70.8% in the 2nd exam than in the 1st exam, at 53.1% (P<0.001). The correct diagnosis rate in the 3rd exam was significantly lower than that in the 2nd exam (60.9% vs. 70.8%; P<0.001) but was still higher than that in the 1st exam (60.9% vs. 53.1%; P<0.001). The difference in proportion of correct diagnosis between the 2nd and the 3rd exams was smaller among routine ME-NBI practitioners (n=6; 79.2% and 76.1%, respectively), compared to that among non-routine practitioners (n=34; 71.6% and 59.8%, respectively) or non-practitioners (n=24; 67.5% and 58.8%, respectively). Conclusion This study revealed that an educational intervention increased correct diagnosis rate of small gastric lesions using the VSCS, diagnosis criteria based on ME-NBI and also showed that the routine use of the modality and the diagnosis criteria was necessary to maintain diagnostic skills. PMID:24733047
Usefulness of Non-Magnifying Narrow-Band Imaging in Screening of Early Esophageal Squamous Cell Carcinoma: A Prospective Comparative Study Using Propensity Score Matching
Nagami, Yasuaki; Tominaga, Kazunari; Machida, Hirohisa; Nakatani, Masami; Kameda, Natsuhiko; Sugimori, Satoshi; Okazaki, Hirotoshi; Tanigawa, Tetsuya; Yamagami, Hirokazu; Kubo, Naoshi; Shiba, Masatsugu; Watanabe, Kenji; Watanabe, Toshio; Iguchi, Hiroyoshi; Fujiwara, Yasuhiro; Ohira, Masaichi; Hirakawa, Kosei; Arakawa, Tetsuo
OBJECTIVES: The usefulness of non-magnifying endoscopy with narrow-band imaging (NBI; NM-NBI) in the screening of early esophageal squamous cell carcinoma (SCC) and high-grade intraepithelial neoplasia (HGIN) remains unclear. Here, we aimed to compare NM-NBI and chromoendoscopy with iodine staining (CE-Iodine) in terms of the diagnostic performance, and to evaluate the usefulness of NM-NBI in detecting early esophageal SCC. METHODS: We prospectively enrolled 202 consecutive patients (male/female=180/22; median age, 67 years) with high-risk factors for esophageal SCC. All patients received endoscopic examination with NM-NBI and CE-Iodine to screen for early esophageal SCC or HGIN. We conducted the examinations sequentially, and calculated the accuracy, sensitivity, and specificity through a per-lesion-based analysis. A propensity score matching analysis was performed to reduce the effects of selection bias, and we compared the respective outcomes according to NM-NBI and CE-Iodine after matching. RESULTS: The accuracy, sensitivity, and specificity of NM-NBI were 77.0, 88.3, and 75.2%, respectively, and those for unstained areas by CE-Iodine were 68.0, 94.2, and 64.0, respectively. The accuracy and specificity of NM-NBI were superior to those of CE-Iodine (P=0.03 and P=0.01, respectively). However, the sensitivity did not significantly differ between NM-NBI and CE-Iodine (P=0.67). The accuracy and specificity of NM-NBI before matching were superior to those of CE-Iodine after matching (P=0.04 and P=0.03). CONCLUSIONS: NM-NBI was useful and reliable for the diagnosis of esophageal SCC and can be a promising screening strategy for early esophageal SCC. PMID:24751580
The microwave emission and transmission characters of deciduous forest at L-band
NASA Astrophysics Data System (ADS)
Zhang, Zhongjun; Yuan, Yu; Zheng, Xingming; Zhu, Xiaoming; Fu, Xiuli
Forest covers about 30% of earth surface, which plays an important role in global forecast and carbon cycle. Monitoring forest biomass, and retrieving soil moisture at forest area, are the main goals of most passive microwave sensors on satellite missions. L-band is the most sensitive frequency among all the frequencies due to its good penetration ability. Because of its variety of the size of scattering components, the complicated structures and species of forest, it is difficult to describe the scattering and attenuation characters of forest in modeling microwave emission at forest area. In this paper, we studied the emissivity and transmissivity of deciduous forest at L(1.4GHz) by model simulation and field experiment. The microwave emission model was based on Matrix-Doubling algorithm. The comparison between simulated emissivity and measured data collected during an experiment at Maryland, USA in 2007 was good. Since theoretical model like Matrix-Doubling is too complicated to be used in retrial application, we mapped the results of Matrix-Doubling to a simple 0th-order model, also called ?-? model, by setting the simulated emissivity to be the emissivity of 0th-order model at the same environment, which 2 unknown variables---opacity ? and effective single scattering albedo ? need to be determined. To valited ? (transmissivity of forest) simulated by Matrix-Doubling, we took an deciduous forest experiment by an L band microwave radiometer under trees at JingYueTan area, Changchun, Jilin Province in April to June in 2014. Thus the ? of forest can be determined. The matching results are presented in this paper. The relationship between LAI and forest microwave characters are discussed.
Soil nitrous oxide emissions following band-incorporation of fertilizer nitrogen and swine manure.
Chantigny, Martin H; Rochette, Philippe; Angers, Denis A; Bittman, Shabtai; Buckley, Katherine; Massķ, Daniel; Bķlanger, Gilles; Eriksen-Hamel, Nikita; Gasser, Marc-Olivier
Treatment of liquid swine manure (LSM) offers opportunities to improve manure nutrient management. However, N2O fluxes and cumulative emissions resulting from application of treated LSM are not well documented. Nitrous oxide emissions were monitored following band-incorporation of 100 kg N ha(-1) of either mineral fertilizer, raw LSM, or four pretreated LSMs (anaerobic digestion; anaerobic digestion + flocculation: filtration; decantation) at the four-leaf stage of corn (Zea mays L.). In a clay soil, a larger proportion of applied N was lost as N2O with the mineral fertilizer (average of 6.6%) than with LSMs (3.1-5.0%), whereas in a loam soil, the proportion of applied N lost as N2O was lower with the mineral fertilizer (average of 0.4%) than with LSMs (1.2-2.4%). Emissions were related to soil NO3 intensity in the clay soil, whereas they were related to water-extractable organic C in the loam soil. This suggests that N2O production was N limited in the clay soil and C limited in the loam soil, and would explain the interaction found between N sources and soil type. The large N2O emission coefficients measured in many treatments, and the contradicting responses among N sources depending on soil type, indicate that (i) the Intergovernmental Panel on Climate Change (IPCC) default value (1%) may seriously underestimate N2O emissions from fine-textured soils where fertilizer N and manure are band-incorporated, and (ii) site-specific factors, such as drainage conditions and soil properties (e.g., texture, organic matter content), have a differential influence on emissions depending on N source. PMID:21043260
Multiyear On-orbit Calibration and Performance of Terra MODIS Thermal Emissive Bands
NASA Technical Reports Server (NTRS)
Xiong, Xiaoxiong; Chiang, Kwo-Fu; Wu, Aisheng; Barnes, William; Guenther, Bruce; Salomonson, Vincent
Since launch in December 1999, Terra MODIS has been making continuous Earth observations for more than seven years. It has produced a broad range of land, ocean, and atmospheric science data products for improvements in studies of global climate and environmental change. Among its 36 spectral bands, there are 20 reflective solar bands (RSB) and 16 thermal emissive bands (TEB). MODIS thermal emissive bands cover the mid-wave infrared (MWIR) and long-wave infrared (LWIR) spectral regions with wavelengths from 3.7 to 14.4pm. They are calibrated on-orbit using an on-board blackbody (BB) with its temperature measured by a set of thermistors on a scan-by-scan basis. This paper will provide a brief overview of MODIS TEB calibration and characterization methodologies and illustrate on-board BB functions and TEB performance over more than seven years of on-orbit operation and calibration. Discussions will be focused on TEB detector short-term stability and noise characterization, and changes in long-term response (or system gain). Results show that Terra MODIS BB operation has been extremely stable since launch. When operated at its nominal controlled temperature of 290K, the BB temperature variation is typically less than +0.30mK on a scan-by-scan basis and there has been no time-dependent temperature drift. In addition to excellent short-term stability, most TEB detectors continue to meet or exceed their specified noise characterization requirements, thus enabling calibration accuracy and science data product quality to be maintained. Excluding the noisy detectors identified pre-launch and those that occurred post-launch, the changes in TEB responses have been less than 0.7% on an annual basis. The optical leak corrections applied to bands 32-36 have been effective and stable over the entire mission
The dust sublimation radius as an outer envelope to the bulk of the narrow Fe Kalpha line emission in Type 1 AGN
Gandhi, Poshak; Kishimoto, Makoto
The Fe Kalpha emission line is the most ubiquitous feature in the X-ray spectra of active galactic nuclei (AGN), but the origin of its narrow core remains uncertain. Here, we investigate the connection between the sizes of the Fe Kalpha core emission regions and the measured sizes of the dusty tori in 13 local Type 1 AGN. The observed Fe Kalpha emission radii (R_fe) are determined from spectrally resolved line widths in X-ray grating spectra, and the dust sublimation radii (R_dust) are measured either from optical/near-infrared reverberation time lags or from resolved near-infrared interferometric data. This direct comparison shows that the dust sublimation radius forms an outer envelope to the bulk of the Fe Kalpha emission. R_fe matches R_dust well in the AGN with the best constrained line widths currently. In a significant fraction of objects without a clear narrow line core, R_fe is similar to, or smaller than the radius of the optical broad line region. These facts place important constraints on the toru...
EXAMINING THE BROADBAND EMISSION SPECTRUM OF WASP-19b: A NEW z-BAND ECLIPSE DETECTION
Zhou, George; Bayliss, Daniel D. R. [Research School of Astronomy and Astrophysics, Australian National University, Cotter Rd, Weston Creek, ACT 2611 (Australia); Kedziora-Chudczer, Lucyna; Bailey, Jeremy, E-mail: email@example.com [School of Physics, University of New South Wales, Sydney, NSW 2052 (Australia)
WASP-19b is one of the most irradiated hot-Jupiters known. Its secondary eclipse is the deepest of all transiting planets and has been measured in multiple optical and infrared bands. We obtained a z-band eclipse observation with a measured depth of 0.080% {+-} 0.029%, using the 2 m Faulkes Telescope South, which is consistent with the results of previous observations. We combined our measurement of the z-band eclipse with previous observations to explore atmosphere models of WASP-19b that are consistent with its broadband spectrum. We use the VSTAR radiative transfer code to examine the effect of varying pressure-temperature profiles and C/O abundance ratios on the emission spectrum of the planet. We find that models with super-solar carbon enrichment best match the observations, which is consistent with previous model retrieval studies. We also include upper atmosphere haze as another dimension in the interpretation of exoplanet emission spectra and find that particles <0.5 {mu}m in size are unlikely to be present in WASP-19b.
Acoustic emission frequency discrimination
NASA Technical Reports Server (NTRS)
Sugg, Frank E. (inventor); Graham, Lloyd J. (inventor)
In acoustic emission nondestructive testing, broadband frequency noise is distinguished from narrow banded acoustic emission signals, since the latter are valid events indicative of structural flaws in the material being examined. This is accomplished by separating out those signals which contain frequency components both within and beyond (either above or below) the range of valid acoustic emission events. Application to acoustic emission monitoring during nondestructive bond verification and proof loading of undensified tiles on the Space Shuttle Orbiter is considered.
A Short Cycle of Narrow-Band UVB Phototherapy in the Early Phase of Long-Term Efalizumab Can Provide a Quicker Remission of Moderate and Severe Psoriasis: A Pilot Study
Cristina Zane; Rossana Capezzera; Marina Venturini; Raffaella Sala; Elena Facchinetti; Alessandra Pedretti; Piergiacomo Calzavara-Pinton
Background: Efalizumab, albeit highly efficient in psoriasis treatment, displays a slower rate of clearance when compared to anti-tumor-necrosis-factor-? drugs. It has been suggested that a combination of treatments might accelerate efalizumab response. Objective: To determine whether the combination of narrow-band ultraviolet B (NB-UVB) phototherapy and efalizumab could improve the therapeutic efficacy of efalizumab alone in moderate to severe psoriasis. Methods:
Model calculation of N2 Vegard-Kaplan band emissions in Martian dayglow
NASA Astrophysics Data System (ADS)
Jain, Sonal Kumar; Bhardwaj, Anil
A model for N2 Vegard-Kaplan (VK) band (A3?u+ - X1?g+) emissions in Martian dayglow has been developed to explain the recent observations made by the Spectroscopy for Investigation of Characteristics of the Atmosphere of Mars (SPICAM) ultraviolet spectrograph aboard Mars Express. Steady state photoelectron fluxes and volume excitation rates have been calculated using the analytical yield spectra technique. Since interstate cascading is important for triplet states of N2, the population of any given level of N2 triplet states is calculated under statistical equilibrium considering direct excitation, cascading, and quenching effects. Relative population of all vibrational levels of each triplet state is calculated in the model. Line of sight intensities and height-integrated overhead intensities have been calculated for VK, first positive (B3?g - A3?u+), second positive (C3?u - B3?g), and Wu-Benesch (W3?u - B3?g) bands of N2. A reduction in the N2 density by a factor of 3 in the Mars thermospheric general circulation model is required to obtain agreement between calculated limb profiles of VK (0-6) and SPICAM observation. Calculations are carried out to asses the impact of model parameters, namely, electron impact cross sections, solar EUV flux, and model atmosphere, on the emission intensities. Constraining the N2/CO2 ratio by SPICAM observations, we suggest the N2/CO2 ratios to be in the range 1.1-1.4% at 120 km, 1.8-3.2% at 140 km, and 4-7% at 170 km. During high solar activity the overhead intensity of N2 VK band emissions would be ś2.5 times higher than that during low solar activity.
Assessment of Still and Moving Images in the Diagnosis of Gastric Lesions Using Magnifying Narrow-Band Imaging in a Prospective Multicenter Trial
Hayashi, Tomoyuki; Doyama, Hisashi; Shirota, Yukihiro; Tsuji, Hirokazu; Marukawa, Youhei; Ohta, Hajime; Miwa, Kazuhiro; Masunaga, Takaharu; Terasaki, Shuichi; Matano, Yutaka; Tsuji, Kunihiro; Kaneko, Yoshibumi; Okada, Toshihide; Kurumaya, Hiroshi; Kaneko, Shuichi
Objectives Magnifying narrow-band imaging (M-NBI) is more accurate than white-light imaging for diagnosing small gastric cancers. However, it is uncertain whether moving M-NBI images have additional effects in the diagnosis of gastric cancers compared with still images. Design A prospective multicenter cohort study. Methods To identify the additional benefits of moving M-NBI images by comparing the diagnostic accuracy of still images only with that of both still and moving images. Still and moving M-NBI images of 40 gastric lesions were obtained by an expert endoscopist prior to this prospective multicenter cohort study. Thirty-four endoscopists from ten different Japanese institutions participated in the prospective multicenter cohort study. Each study participant was first tested using only still M-NBI images (still image test), then tested 1 month later using both still and moving M-NBI images (moving image test). The main outcome was a difference in the diagnostic accuracy of cancerous versus noncancerous lesions between the still image test and the moving image test. Results Thirty-four endoscopists were analysed. There were no significant difference of cancerous versus noncancerous lesions between still and moving image tests in the diagnostic accuracy (59.9% versus 61.5%), sensitivity (53.4% versus 55.9%), and specificity (67.0% versus 67.6%). And there were no significant difference in the diagnostic accuracy between still and moving image tests of demarcation line (65.4% versus 65.5%), microvascular pattern (56.7% versus 56.9%), and microsurface pattern (48.1% versus 50.9%). Diagnostic accuracy showed no significant difference between the still and moving image tests in the subgroups of endoscopic findings of the lesions. Conclusions The addition of moving M-NBI images to still M-NBI images does not improve the diagnostic accuracy for gastric lesions. It is reasonable to concentrate on taking sharp still M-NBI images during endoscopic observation and use them for diagnosis. Trial registration Umin.ac.jp UMIN-CTR000008048 PMID:24988209
Monitoring water stress and fruit quality in an orange orchard under regulated deficit irrigation using narrow-band structural and physiological remote sensing indices
NASA Astrophysics Data System (ADS)
Stagakis, S.; Gonzßlez-Dugo, V.; Cid, P.; Guillķn-Climent, M. L.; Zarco-Tejada, P. J.
This paper deals with the monitoring of water status and the assessment of the effect of stress on citrus fruit quality using structural and physiological remote sensing indices. Four flights were conducted over a citrus orchard in 2009 using an unmanned aerial vehicle (UAV) carrying a multispectral camera with six narrow spectral bands in the visible and near infrared. Physiological indices such as the Photochemical Reflectance Index (PRI570), a new structurally robust PRI formulation that uses the 515 nm as the reference band (PRI515), and a chlorophyll ratio (R700/R670) were compared against the Normalized Difference Vegetation Index (NDVI), Renormalized Difference Vegetation Index (RDVI) and Modified Triangular Vegetation Index (MTVI) canopy structural indices for their performance in tracking water status and the effects of sustained water stress on fruit quality at harvest. The irrigation setup in the commercial orchard was compared against a treatment scheduled to satisfy full requirements (based on estimated crop evapotranspiration) using two regulated deficit irrigation (RDI) strategies. The water status of the trees throughout the experiment was monitored with frequent field measurements of stem water potential (?x), while titratable acidity (TA) and total soluble solids (TSS) were measured at harvest on selected trees from each irrigation treatment. The high spatial resolution of the multispectral imagery (30 cm pixel size) enabled identification of pure tree crown components, extracting the tree reflectance from shaded, sunlit and aggregated pixels. The physiological and structural indices were then calculated from each tree at the following levels: (i) pure sunlit tree crown, (ii) entire crown, aggregating the within-crown shadows, and (iii) simulating a lower resolution pixel, including tree crown, sunlit and shaded soil pixels. The resulting analysis demonstrated that both PRI formulations were able to track water status, except when water stress altered canopy structure. In such cases, PRI570 was more affected than PRI515 by the structural changes caused by sustained water stress throughout the season. Both PRI formulations were proven to serve as pre-visual water stress indicators linked to fruit quality TSS and TA parameters (r2 = 0.69 for PRI515 vs TSS; r2 = 0.58 vs TA). In contrast, the chlorophyll (R700/R670) and structural indices (NDVI, RDVI, MTVI) showed poor relationships with fruit quality and water status levels (r2 = 0.04 for NDVI vs TSS; r2 = 0.19 vs TA). The two PRI formulations showed strong relationships with the field-measured fruit quality parameters in September, the beginning of stage III, which appeared to be the period most sensitive to water stress and the most critical for assessing fruit quality in citrus. Both PRI515 and PRI570 showed similar performance for the two scales assessed (sunlit crown and entire crown), demonstrating that within-crown component separation is not needed in citrus tree crowns where the shaded vegetation component is small. However, the simulation conducted through spatial resampling on tree + soil aggregated pixels revealed that the physiological indices were highly affected by soil reflectance and between-tree shadows, showing that for TSS vs PRI515 the relationship dropped from r2 = 0.69 to r2 = 0.38 when aggregating soil + crown components. This work confirms a previous study that demonstrated the link between PRI570, water stress, and fruit quality, while also making progress in assessing the new PRI formulation (PRI515), the within-crown shadow effects on the physiological indices, and the need for high resolution imagery to target individual tree crowns for the purpose of evaluating the effects of water stress on fruit quality in citrus.
Band-limited Green's Functions for Quantitative Evaluation of Acoustic Emission Using the Finite Element Method
NASA Technical Reports Server (NTRS)
Leser, William P.; Yuan, Fuh-Gwo; Leser, William P.
A method of numerically estimating dynamic Green's functions using the finite element method is proposed. These Green's functions are accurate in a limited frequency range dependent on the mesh size used to generate them. This range can often match or exceed the frequency sensitivity of the traditional acoustic emission sensors. An algorithm is also developed to characterize an acoustic emission source by obtaining information about its strength and temporal dependence. This information can then be used to reproduce the source in a finite element model for further analysis. Numerical examples are presented that demonstrate the ability of the band-limited Green's functions approach to determine the moment tensor coefficients of several reference signals to within seven percent, as well as accurately reproduce the source-time function.
Observational Studies on the Near-infrared Unidentified Emission Bands in Galactic H II Regions
NASA Astrophysics Data System (ADS)
Mori, Tamami I.; Onaka, Takashi; Sakon, Itsuki; Ishihara, Daisuke; Shimonishi, Takashi; Ohsawa, Ryou; Bell, Aaron C.
Using a large collection of near-infrared spectra (2.5-5.4 ?m) of Galactic H II regions and H II region-like objects, we perform a systematic investigation of astronomical polycyclic aromatic hydrocarbon (PAH) features. Thirty-six objects were observed using the infrared camera on board the AKARI satellite as a part of a director's time program. In addition to the well known 3.3-3.6 ?m features, most spectra show a relatively weak emission feature at 5.22 ?m with sufficient signal-to-noise ratios, which we identify as the PAH 5.25 ?m band (previously reported). By careful analysis, we find good correlations between the 5.25 ?m band and both the aromatic hydrocarbon feature at 3.3 ?m and the aliphatic hydrocarbon features at around 3.4-3.6 ?m. The present results give us convincing evidence that the astronomical 5.25 ?m band is associated with C-H vibrations, as suggested by previous studies, and show its potential to probe the PAH size distribution. The analysis also shows that the aliphatic-to-aromatic ratio of I 3.4-3.6 ?m/I 3.3 ?m decreases against the ratio of the 3.7 ?m continuum intensity to the 3.3 ?m band, I cont, 3.7 ?m/I 3.3 ?m, which is an indicator of the ionization fraction of PAHs. The midinfrared color of I 9 ?m/I 18 ?m also declines steeply against the ratio of the hydrogen recombination line Br? at 4.05 ?m to the 3.3 ?m band, I Br?/I 3.3 ?m. These facts indicate possible dust processing inside or at the boundary of ionized gas.
Acoustic emissions and porosity reduction during growth of discrete compaction bands in porous sandstone
NASA Astrophysics Data System (ADS)
Baud, P.; Meredith, P.; Boon, S.
Recent field and laboratory studies have documented the occurrence of strain localisation in porous sandstones. The localised failure mode can be in shear or compaction, in the form of conjugate shear or compaction bands oriented at relatively high angles to the maximum compression direction. Compaction bands in particular have drawn a lot of interest because these localized structures could potentially act as barriers for fluid flow in reservoirs and aquifers. To elucidate the complexity of the occurrence and growth of discrete compaction bands in porous sandstones, we performed a series of triaxial deformation experiments on Bentheim sandstone. The experiments were done on saturated samples under drained condition at different confining and pore pressures. During the experiments, confining pressure and pore pressure were controlled to within about 1% with the help of two external servo-controlled pressure intensifiers. Acoustic emission (AE) activity was monitored continuously during the experiments by up to 8 piezoelectric transducers attached to the sample. For each transducer, several characteristics of the AE signals, such as amplitude and energy were recorded continuously. Our results show that the occurrence and growth of compaction bands was followed by small stress drops in the mechanical data and very large AE outputs. From the AE data, we calculated the evolution of the seismic b-value associated with strain localisation in the compactive regime. During the compaction process, our fully servo-controlled experimental set-up enabled us also to follow the step-by-step decrease in porosity in the samples associated with the sequential development of discrete compaction bands.
Geolocation databases for white space devices in the UHF TV bands: Specification of maximum permitted emission levels
Hamid Reza Karimi
In this paper we present the detailed calculations which a geolocation database would need to perform in order to derive location-specific maximum permitted emission levels for white space devices (WSDs) operating in digital terrestrial TV (DTT) bands. We introduce a novel methodology for the calculation of such emission levels, whereby the extent of protection afforded to the DTT service is
Multi-band constraints on the nature of emission line galaxies
Balmaverde, B
Our aim is to explore the nature of emission line galaxies by combining high-resolution observations obtained in different bands to understand which objects are powered by an Active Galactic Nucleus(AGN). From the spectroscopic Palomar survey of nearby bright galaxies, we selected a sample of 18 objects observed with HST, Chandra, and VLA. No connection is found between X-ray and emission line luminosities from ground-based data, unlike what is found for brighter AGN. Conversely, a strong correlation emerges when using the HST spectroscopic data, which are extracted on a much smaller aperture. This suggests that the HST data better isolate the AGN component when one is present, while ground-based line measurements are affected by diffuse emission from the host galaxies. The sample separates into two populations. The 11 objects belonging to the first class have an equivalent width of the [OIII] emission line measured from HST data EW([OIII])>~2 A and are associated with an X-ray nuclear source; in the second g...
Results and Lessons from MODIS Thermal Emissive Bands Calibration: Pre-launch to On-orbit
NASA Technical Reports Server (NTRS)
Xiong, X.; Chiang, K.; Barnes, W. L.; Guenther, B.
MODIS is a major instrument for the NASA EOS Terra (launched in December 1999) and Aqua (launched in May 2002) missions. It was designed and built to enhance and extend its heritage sensors' measurements and data records with applications covering a wide range of studies of the Earth's land, oceans, and atmosphere. Its 16 thermal emissive bands (TEB), each with 10 detectors, are located on the two cold focal plane assemblies (FPAs) controlled by a passive radiative cooler. Because of instrument design complexity and stringent calibration requirements, extensive calibration and characterization activities were conducted pre-launch by the sensor vendor for both Terra and Aqua MODIS. For TEB, these activities include characterization of detectors' noise and non-linearity and evaluation of their radiometric performance in thermal vacuum at difference instrument temperatures and FPA temperatures. In addition TEB system level response versus scan-angle (RVS) and relative spectral response (RSR) were characterized. MODIS TEB radiometric calibration transfer from pre-launch to on-orbit was performed using spectral bands' responses to the instrument on-board blackbody and a laboratory blackbody calibration source (BCS) traceable to NIST standards. This paper provides a summary of MODIS TEB pre-launch and on-orbit calibration and characterization activities, challenges, data analysis results, and lessons learned with focus on sensors' radiometric performance. A comparison between Terra and Aqua MODIS TEB performance is also presented. A similar summary for the reflective solar bands (RSB) is reported in a separate paper in these proceedings.
Model of the Optical Emission of a Driven Semiconductor Quantum Dot: Phonon-Enhanced Coherent Scattering and Off-Resonant Sideband Narrowing
NASA Astrophysics Data System (ADS)
McCutcheon, Dara P. S.; Nazir, Ahsan
We study the crucial role played by the solid-state environment in determining the photon emission characteristics of a driven quantum dot. For resonant driving, we predict a phonon enhancement of the coherently emitted radiation field with increasing driving strength, in stark contrast to the conventional expectation of a rapidly decreasing fraction of coherent emission with stronger driving. This surprising behavior results from thermalization of the dot with respect to the phonon bath and leads to a nonstandard regime of resonance fluorescence in which significant coherent scattering and the Mollow triplet coexist. Off resonance, we show that despite the phonon influence, narrowing of dot spectral sideband widths can occur in certain regimes, consistent with an experimental trend.
Performance of MODIS Thermal Emissive Bands On-orbit Calibration Algorithms
NASA Technical Reports Server (NTRS)
Xiong, Xiaoxiong; Chang, T.
Two nearly identical copies of the Moderate Resolution Imaging Spectroradiometer (MODIS) are currently operated on-board the Terra and Aqua spacecrafts, launched in December 1999 and May 2002, respectively. Together, they have produced an unprecedented amount of science data products, which are widely used for the studies of changes in the Earth's system of land, oceans, and atmosphere. MODIS is a cross-track scanning radiometer, which uses a two-sided scan mirror and collects data continuously over a wide scan angle range (+/-55 degree relative to the instrument nadir) each scan of 1.47 seconds. It has 36 spectral bands with wavelengths ranging from visible (VIS) to long-wave infrared (LWIR). MODIS bands 1-19 and 26 are the reflective solar bands (RSB) and bands 20-25 and 27-36 are the thermal emissive bands (TEB). MODIS was developed and designed with improvements made over its heritage sensors (such as AVHRR and Landsat) and, in particular, with more stringent calibration requirements. Because of this, MODIS was built with a set of state-of-art on-board calibrators (OBC), which include a solar diffuser (SD), a solar diffuser stability monitor (SDSM), a blackbody (BB), a spectroradiometric calibration assembly (SRCA), and a space view (SV) port. With the exception of view angle differences, MODIS OBC measurements and the Earth View (EV) observations are made via the same optical path. MODIS TEB have a total of 160 individual TEB detectors (10 per band), which are located on two cold focal plane assemblies (CFPA). For nominal on-orbit operation, the CFPA temperature is controlled at 83K via a passive radiative cooler. For the TEB, the calibration requirements at specified typical scene radiances are less than or equal to 1% with an exception for the fire detection (low gain) band. MODIS TEB on-orbit calibration is performed on a scan-by-scan basis using a quadratic calibration algorithm, and data collected from sensor responses to the onboard BB and SV. The BB serves as the thermal calibration source and the SV provides measurements for the sensor's background and offsets. MODIS on-board BB is a v-grooved plate with its temperature measured using 12 platinum resistive thermistors (PRT) uniformly embedded in the BB substrate. All the BB thermistors were characterized pre-launch with reference to the NIST temperature standards. Unlike typical BB operations in many heritage sensors, which have no temperature control capability, the MODIS on-board BB can be operated at any temperatures between instrument ambient (about 270K) and 315K and can also be varied continuously within this range. This feature has significantly enhanced the MODIS' capability of tracking and updating the TEB nonlinear calibration coefficients over its entire mission. Following a brief description of MODIS TEB on-orbit calibration methodologies and its onboard BB operational activities, this paper provides a comprehensive performance assessment of MODIS TEB quadratic calibration algorithm. It examines the scan-by-scan, orbit-by-orbit, daily, and seasonal variations of detector responses and associated impact due changes in the CFPA and instrument temperatures. Specifically, this paper will analyze the contribution by each individual thermal emissive source term (BB, scan cavity, and scan mirror), the impact on the Level 1 B data product quality due to pre-launch and on-orbit calibration uncertainties. A comparison of Terra and Aqua TEB on-orbit performance, lessons learned, and suggestions for future improvements will also be made.
Impact of Conifer Forest Litter on Microwave Emission at L-Band
NASA Technical Reports Server (NTRS)
Kurum, Mehmet; O'Neill, Peggy E.; Lang, Roger H.; Cosh, Michael H.; Joseph, Alicia T.; Jackson, Thomas J.
This study reports on the utilization of microwave modeling, together with ground truth, and L-band (1.4-GHz) brightness temperatures to investigate the passive microwave characteristics of a conifer forest floor. The microwave data were acquired over a natural Virginia Pine forest in Maryland by a ground-based microwave active/passive instrument system in 2008/2009. Ground measurements of the tree biophysical parameters and forest floor characteristics were obtained during the field campaign. The test site consisted of medium-sized evergreen conifers with an average height of 12 m and average diameters at breast height of 12.6 cm. The site is a typical pine forest site in that there is a surface layer of loose debris/needles and an organic transition layer above the mineral soil. In an effort to characterize and model the impact of the surface litter layer, an experiment was conducted on a day with wet soil conditions, which involved removal of the surface litter layer from one half of the test site while keeping the other half undisturbed. The observations showed detectable decrease in emissivity for both polarizations after the surface litter layer was removed. A first-order radiative transfer model of the forest stands including the multilayer nature of the forest floor in conjunction with the ground truth data are used to compute forest emission. The model calculations reproduced the major features of the experimental data over the entire duration, which included the effects of surface litter and ground moisture content on overall emission. Both theory and experimental results confirm that the litter layer increases the observed canopy brightness temperature and obscure the soil emission.
Structural phase transition, narrow band gap, and room-temperature ferromagnetism in [KNbO3]1-x[BaNi1/2Nb1/2O3-?]x ferroelectrics
NASA Astrophysics Data System (ADS)
Zhou, Wenliang; Deng, Hongmei; Yang, Pingxiong; Chu, Junhao
Structural phase transition, narrow band gap (Eg), and room-temperature ferromagnetism (RTFM) have been observed in the [KNbO3]1-x[BaNi1/2Nb1/2O3-?]x (KBNNO) ceramics. All the samples have single phase perovskite structure, but exhibit a gradual transition behaviour from the orthorhombic to a cubic structure with the increase of x. Raman spectroscopy analysis not only corroborates this doping-induced change in normal structure but also shows the local crystal symmetry for x ? 0.1 compositions to deviate from the idealized cubic perovskite structure. A possible mechanism for the observed specific changes in lattice structure is discussed. Moreover, it is noted that KBNNO with compositions x = 0.1-0.3 have quite narrow Eg of below 1.5 eV, much smaller than the 3.2 eV band gap of parent KNbO3 (KNO), which is due to the increasing Ni 3d electronic states within the gap of KNO. Furthermore, the KBNNO materials present RTFM near a tetragonal to cubic phase boundary. With increasing x from 0 to 0.3, the magnetism of the samples develops from diamagnetism to ferromagnetism and paramagnetism, originating from the ferromagnetic-antiferromagnetic competition. These results are helpful in the deeper understanding of phase transitions, band gap tunability, and magnetism variations in perovskite oxides and show the potential role, such materials can play, in perovskite solar cells and multiferroic applications.
Band gap engineering, band edge emission, and p-type conductivity in wide-gap LaCuOS1-xSex oxychalcogenides
NASA Astrophysics Data System (ADS)
Ueda, Kazushige; Hosono, Hideo
The preparation of LaCuOS1-xSex solid solutions (x=0.0, 0.25, 0.5, 0.75, and 1.0) was attempted to control their energy gap and band edge emission energy. X-ray diffraction analysis revealed that the lattice constant of LaCuOS1-xSex increased linearly with increasing x, indicating the formation of a complete solid solution in the LaCuOS-LaCuOSe system. The energy gap estimated from the diffuse reflectance spectra varied continuously from ś3.1 eV for x=0 to ś2.8 eV for x=1. The sharp emission near the absorption edge was observed in all samples at room temperature under ultraviolet light irradiation. p-type electrical conduction in these materials was confirmed by Seebeck measurements, and the conductivity was enhanced by substitution of Sr for La. These results demonstrated that the formation of the solid solutions enabled band gap engineering in LaCuOS1-xSex oxychalcogenides keeping their band edge emission feature and p-type conductivity.
Aqua MODIS Thermal Emissive Band On-Orbit Calibration, Characterization, and Performance
NASA Technical Reports Server (NTRS)
Xiong, Xiaoxiong; Wenny, Brian N.; Wu, Aisheng; Barnes, William L.; Salomonson, Vincent V.
The NASA's Earth Observing System Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) has continued to operate with satisfactory performance since its launch in May 2002, exceeding its nominal six-year design lifetime. Its continuous Earth observations have been used to generate many science data products for studies of the Earth's, system. MODIS has 36 spectral bands; 20 reflective solar bands and 16 thermal emissive bands (TEBs). All TEB observations are made at 1-km nadir spatial resolution with spectral wavelengths from 3.7 to 14.4 pm. Primary applications of MODIS TEB 'include surface, cloud, and atmospheric temperatures, water vapor, and cloud top altitude. MODIS TEB on-orbit calibration uses a quadratic algorithm with its calibration coefficients derived using an onboard blackbody (BB). This paper will present Aqua MODIS TEB on-orbit calibration, characterization, and performance over its six-year mission. Examples of instrument thermal behavior, BB temperature stability, detector short-term stability, and changes in long-term response (or system gain) will be presented. Comparisons will also be made with Terra MODIS, launched in December 1999. On-orbit results show that Aqua MODIS and its focal plane temperatures have behaved normally. BB temperature has remained extremely stable with typical scan -to-scan variations of less than +/-0.15 mK. Most TEB detectors continue to exceed their specified signal-to-noise ratio requirements, exhibiting excellent short-term stability and calibration accuracy. Excluding a few noisy detectors, either identified prelaunch or occurring postlaunch, on-orbit changes in TEB responses have been less than 0.5% on an annual basis. By comparison; the overall Aqua TEB performance has been better than that of Terra MODIS,
On-orbit Characterization of RVS for MODIS Thermal Emissive Bands
NASA Technical Reports Server (NTRS)
Xiong, X.; Salomonson, V.; Chiang, K.; Wu, A.; Guenther, B.; Barnes, W.
Response versus scan angle (RVS) is a key calibration parameter for remote sensing radiometers that make observations using a scanning optical system, such as a scan mirror in MODIS and GLI or a rotating telescope in SeaWiFS and VIIRS, since the calibration is typically performed at a fixed viewing angle while the Earth scene observations are made over a range of viewing angles. Terra MODIS has been in operation for more than four years since its launch in December 1999. It has 36 spectral bands covering spectral range from visible (VIS) to long-wave infrared (LWIR). It is a cross-track scanning radiometer using a two-sided paddle wheel scan mirror, making observations over a wide field of view (FOV) of +/-55 deg from the instrument nadir. This paper describes on-orbit characterization of MODIS RVS for its thermal emissive bands (TEB), using the Earth view data collected during Terra spacecraft deep space maneuvers (DSM). Comparisons with pre-launch analysis and early on-orbit measurements are also provided.
A Comparison of Hard X-ray Photon Indices and Iron K' Emission Lines in X-ray Luminous Narrow- and Broad-line Seyfert 1 Galaxies
NASA Astrophysics Data System (ADS)
Zhou, XinLin
We use publicly available XMM-Newton data to systematically compare the hard X-ray photon indices, ś2-10 keV, and the iron K' emission lines of narrow- and broad-line Seyfert 1 (NLS1 and BLS1) galaxies. We compile a flux-limited (f 2-10 keV >= 1 ū 10^{-12} erg s^{-1} cm^{-2}) sample including 114 radio-quiet objects, with the 2-10 keV luminosity ranging from 1041 to 1045 erg s^{-1}. Our main results are: (1) NLS1s and BLS1s show similar luminosity distributions; (2) the weighted means of ś2-10 keV of NLS1s, BLS1s, and the total sample are 2.04 ▒ 0.04, 1.74 ▒ 0.02, and 1.84 ▒ 0.02, respectively; a significant anti-correlation between ś2-10 keV and FWHM H?suggests that ś2-10 keV > 2.0 may be taken to indicate the X-ray luminous NLS1 type; (3) the 6.4 keV narrow iron K' lines from NLS1s are generally weaker than that from BLS1s; this would indicate a smaller covering factor of the dusty tori in NLS1s if the line emission originates from the inner boundary region of the dusty torus in an active galactic nucleus; and (4) all the broadened iron K' lines with intrinsic width £╔>0.5 keV correspond to FWHM H? <=4000 km s^{-1}.
A Comparison of Hard X-ray Photon Indices and Iron K? Emission Lines in X-ray Luminous Narrow- and Broad-line Seyfert 1 Galaxies
NASA Astrophysics Data System (ADS)
Zhou, Xin-Lin; Zhang, Shuang-Nan
We use publicly available XMM-Newton data to systematically compare the hard X-ray photon indices, ?2-10 keV , and the iron K? emission lines of narrow- and broad-line Seyfert 1 (NLS1 and BLS1) galaxies. We compile a flux-limited (f 2-10 keV >= 1 ū 10-12 erg s-1 cm-2) sample including 114 radio-quiet objects, with the 2-10 keV luminosity ranging from 1041 to 1045 erg s-1. Our main results are: (1) NLS1s and BLS1s show similar luminosity distributions; (2) the weighted means of ?2-10 keV of NLS1s, BLS1s, and the total sample are 2.04 ▒ 0.04, 1.74 ▒ 0.02, and 1.84 ▒ 0.02, respectively; a significant anti-correlation between ?2-10 keV and FWHMH? suggests that ?2-10 keV > 2.0 may be taken to indicate the X-ray luminous NLS1 type; (3) the 6.4 keV narrow iron K? lines from NLS1s are generally weaker than that from BLS1s; this would indicate a smaller covering factor of the dusty tori in NLS1s if the line emission originates from the inner boundary region of the dusty torus in an active galactic nucleus; and (4) all the broadened iron K? lines with intrinsic width ?>0.5 keV correspond to FWHMH? <=4000 km s-1.
The Ground-based H-, K-, and L-band Absolute Emission Spectra of HD 209458b
NASA Astrophysics Data System (ADS)
Zellem, Robert T.; Griffith, Caitlin A.; Deroo, Pieter; Swain, Mark R.; Waldmann, Ingo P.
Here we explore the capabilities of NASA's 3.0 m Infrared Telescope Facility (IRTF) and SpeX spectrometer and the 5.08 m Hale telescope with the TripleSpec spectrometer with near-infrared H-, K-, and L-band measurements of HD 209458b's secondary eclipse. Our IRTF/SpeX data are the first absolute L-band spectroscopic emission measurements of any exoplanet other than the hot Jupiter HD 189733b. Previous measurements of HD 189733b's L band indicate bright emission hypothesized to result from non-LTE CH4 ?3 fluorescence. We do not detect a similar bright 3.3 ?m feature to ~3?, suggesting that fluorescence does not need to be invoked to explain HD 209458b's L-band measurements. The validity of our observation and reduction techniques, which decrease the flux variance by up to 2.8 orders of magnitude, is reinforced by 1? agreement with existent Hubble/NICMOS and Spitzer/IRAC1 observations that overlap the H, K, and L bands, suggesting that both IRTF/SpeX and Palomar/TripleSpec can measure an exoplanet's emission with high precision.
Alterations in Cochlear Function after Exposure to Short Term Broad Band Noise Assessed by Otoacoustic Emissions
Reddy, Prasen; M M, Kavitha; Khavasi, Prabhu; Doddamani, S S
Background: Sudden or chronic exposure to sound alters the functioning of cochlea. This results in temporary or permanent alteration of functioning of cochlear cells. Alteration of functioning of outer hair cells (OHC) of cochlea following exposure to noise can be assessed by measurement of transient otoacoustic emissions (TEOAE). Such a measurement is of great clinical importance in early detection of the damage to the OHC. Aim: In this study we aim to study effect of noise on outer hair cell function by studying the changes in TEOAEÆs amplitude following exposure to short term broad band noise in healthy volunteers. Materials and Methods: Twenty volunteersÆ ten males and ten females participated in the study. They underwent pure tone and impedance audiometry to rule out ear pathology. Then pre-exposure TEOAEÆs were recorded. After that they were exposed to broad band noise for two minutes. After gap of five minutes again TEOAEÆs were recorded. Pre and post exposure amplitude of TEOAEÆs was analysed statistically.s Results: There was statistically significant difference between pre exposure and post-exposure amplitude of TEOAEÆs. Pre and post exposure values for A & B amplitudes showed p-value of 0.0001 whereas values for A-B amplitude showed p-value of 0.0001. Conclusion: Measurement of TEOAEÆs can detect early changes in the functioning of outer hair cells which cannot be picked by routine pure tone audiometry. Thus they can be used in assessing early changes in cochlear function following exposure to noise in individuals exposed to sudden noise or working in noisy environments. Thus preventive methods to reduce the noise induced hearing loss in such individuals can be implemented. PMID:25386468
Study on Coexistence of a Narrow Band System with Terrestrial DTV System: Focused on DTV White Space Utilization with TETRA Release 1
Heejoong Kim; Hyungoo Yoon; Hideki Sunahara; Akira Kato
Efficient use of digital TV spectrum is becoming one of global issues when the transition to DTV is completed. Various wideband services including spectrum sensing application are mainly discussed currently. However, there are critical issues with broadcasters as incumbent users in the DTV band. Therefore, the narrowband applications should also be considered for practical use of White Space for more
Spatial & Kinematical Resolution of the Narrow-Line Region of NGC 1068 with STIS: Associated Absorbers in Emission?
NASA Astrophysics Data System (ADS)
Cecil, G.; Dopita, M. A.; Groves, B.; Ferruit, P.; Pecontal, E.; Wilson, A. S.; Binette, L.
A grid of deep HST/STIS M-grating spectra resolve completely the [O III] & H? line profiles across most of the NLR of NGC 1068, and are compared to emission-line structures visible in the FOC image. We find emission knots with radial velocities blueshifted consistently by up to 3200 km s-1 relative to galaxy systemic, that lie 35 to 70 pc NE of the nucleus up to 35 pc from the radio jet, emit several % of the NLR line flux, coincide with a region of collisionally ionized X-ray & IR coronal-line emitting gas, show gradients in radial velocities of up to 2000 km s-1 in 7 pc, have total velocity extents of up to 1250 km s-1, have ionization parameters >>1, ionized masses ~ 100 Msun (for density 104 cm-3), and follow the overall trend of radial acceleration from the nucleus. We argue that the knots are ablata undergoing radiative acceleration from jet-agitated massive clouds. Integral-field spectra from the CFHT are used to constrain properties of the knots and clouds. The knots are good candidates for the UV associated absorbers seen projected on the continua of other AGN. Work supported by NASA grant GO-7353 from STScI
Impurity states are the origin of yellow-band emission in GaN structures produced by epitaxial lateral overgrowth
Li, X. [Department of Chemistry, Materials Research Laboratory and Beckman Institute, University of Illinois, Urbana, Illinois 61801 (United States)] [Department of Chemistry, Materials Research Laboratory and Beckman Institute, University of Illinois, Urbana, Illinois 61801 (United States); Bohn, P. W. [Department of Chemistry, Materials Research Laboratory and Beckman Institute, University of Illinois, Urbana, Illinois 61801 (United States)] [Department of Chemistry, Materials Research Laboratory and Beckman Institute, University of Illinois, Urbana, Illinois 61801 (United States); Coleman, J. J. [Department of Electrical and Computer Engineering and Microelectronics Laboratory, University of Illinois, Urbana, Illinois 61801 (United States)] [Department of Electrical and Computer Engineering and Microelectronics Laboratory, University of Illinois, Urbana, Illinois 61801 (United States)
GaN grown by selective area epitaxy and subsequent lateral overgrowth exhibits sharply peaked anisotropic structures in the form of hexagonal pyramids and ridges. Spatially resolved optical emission from these structures, using both cathodoluminescence and collection-mode near-field scanning optical microscopy, of radiation centered near 550 nm, the so-called yellow band, indicates that the emission arises predominantly from the apex regions of the pyramids and ridges. In contrast, transmission electron microscopy shows that the apex region is nearly dislocation free and that dislocations cluster at the vertical growth core region. The spatial separation of the dislocations and optical emission indicates that the yellow-band emission has no direct relationship to dislocations. The observation of yellow-band emission strongly localized in the apical regions of both types of structures and the tendency of impurity species to concentrate in these areas argues that it arises instead from impurity states, the most likely candidate of which is a complex formed between a gallium vacancy, V{sub Ga}, and Si or O. (c) 1999 American Institute of Physics.
C{sub 2} swan band emission intensity as a function of C{sub 2} density.
Goyette, A. N.; Lawler, J. E.; Anderson, L. W.; Gruen, D. M.; McCauley, T. G.; Zhou, D.; Krauss, A. R.; Univ. of Wisconsin
We report the systematic comparison of the optical emission intensity of the d {sup 3}{Pi} {yields} a {sup 3}{Pi} (0, 0) vibrational band of the C{sub 2} Swan system with the absolute C{sub 2} concentration in Ar/H{sub 2}/CH{sub 4} and Ar/H{sub 2}/C{sub 60} microwave plasmas used in the deposition of nanocrystalline diamond. The absolute C{sub 2} concentration is obtained using white-light absorption spectroscopy. Emission intensity correlates linearly with C{sub 2} density for variations of several plasma parameters and across two decades of species concentration. Although optical emission intensity generally is not an accurate quantitative diagnostic for gas phase species concentrations, these results confirm the reliability of the (0,0) Swan band for relative determination of C{sub 2} density with high sensitivity under conditions used for hydrogen-deficient plasma-enhanced chemical vapor deposition of diamond.
Structural phase transition, narrow band gap, and room-temperature ferromagnetism in [KNbO{sub 3}]{sub 1?x}[BaNi{sub 1/2}Nb{sub 1/2}O{sub 3??}]{sub x} ferroelectrics
Zhou, Wenliang; Yang, Pingxiong, E-mail: firstname.lastname@example.com; Chu, Junhao [Key Laboratory of Polar Materials and Devices, Ministry of Education, Department of Electronic Engineering, East China Normal University, Shanghai 200241 (China); Deng, Hongmei [Instrumental Analysis and Research Center, Institute of Materials, Shanghai University, 99 Shangda Road, Shanghai 200444 (China)
Structural phase transition, narrow band gap (E{sub g}), and room-temperature ferromagnetism (RTFM) have been observed in the [KNbO{sub 3}]{sub 1?x}[BaNi{sub 1/2}Nb{sub 1/2}O{sub 3??}]{sub x} (KBNNO) ceramics. All the samples have single phase perovskite structure, but exhibit a gradual transition behaviour from the orthorhombic to a cubic structure with the increase of x. Raman spectroscopy analysis not only corroborates this doping-induced change in normal structure but also shows the local crystal symmetry for x ? 0.1 compositions to deviate from the idealized cubic perovskite structure. A possible mechanism for the observed specific changes in lattice structure is discussed. Moreover, it is noted that KBNNO with compositions x?=?0.1¢0.3 have quite narrow E{sub g} of below 1.5?eV, much smaller than the 3.2?eV band gap of parent KNbO{sub 3} (KNO), which is due to the increasing Ni 3d electronic states within the gap of KNO. Furthermore, the KBNNO materials present RTFM near a tetragonal to cubic phase boundary. With increasing x from 0 to 0.3, the magnetism of the samples develops from diamagnetism to ferromagnetism and paramagnetism, originating from the ferromagnetic¢antiferromagnetic competition. These results are helpful in the deeper understanding of phase transitions, band gap tunability, and magnetism variations in perovskite oxides and show the potential role, such materials can play, in perovskite solar cells and multiferroic applications.
Continuous tuning of a narrow-band terahertz wave in periodically poled stoichiometric LiTaO3 crystal with a fan-out grating structure
NASA Astrophysics Data System (ADS)
Yu, Nan Ei; Oh, Myoung-Kyu; Kang, Hoonsoo; Jung, Changsoo; Kim, Bok Hyeon; Lee, Kyu-Sup; Ko, Do-Kyeong; Takekawa, Shunji; Kitamura, Kenji
Continuous tuning of terahertz waves was demonstrated with seamless change in grating period in a periodically poled stoichiometric lithium tantalite (SLT) crystal. The periodically poled fan-out structure allows wide tunability such as 610 GHz with the bandwidth as narrow as 17 GHz at a carrier frequency of 1.00 THz. Temperature-dependent measurements show a gradual intensity increase of the THz pulses as the temperature decreases. Furthermore, absorption and refractive index of SLT in the THz range were estimated and compared with those of LiNbO3 (LN). The absorption coefficient of the LT crystal at ordinary wave was almost half of that in the LN crystal. SLT could be one of the powerful crystals for high-power THz generation with large optical aperture because of the fewer defects inside the crystal.
Out-of-band emission suppression techniques based on a generalized OFDM framework
NASA Astrophysics Data System (ADS)
You, Zihao; Fang, Juan; Lu, I.-Tai
Orthogonal frequency division multiplexing (OFDM)-based cognitive radio (CR) systems suffer from the large out-of-band emission (OOBE) that may interfere with other users. Since most existing OFDM OOBE suppression schemes are derived on the base of an original OFDM system without any other scheme, we first propose a generalized OFDM framework that is capable of describing these schemes no matter whether any one or more of the schemes is applied. Then, according to the place where these schemes are implemented in our framework, they are classified into three groups, namely symbol mapping techniques, precoding techniques, and time-domain techniques. Finally, based on the proposed framework, we propose three new schemes by combining a precoding scheme named singular value decomposition (SVD) precoding with three other schemes from the three groups, namely spectral precoding, N-continuous symbol mapping, and filtering. Numerical results show the power spectral density (PSD), peak-to-average power ratio (PAPR), and bit error rate (BER) performances of the three proposed schemes. Since the individual schemes have complementary characteristics, the three proposed combined schemes are constructed to maintain the merits and avoid the drawbacks of the individual schemes involved. Thus, it is demonstrated that the proposed framework can be employed to develop other new combined OOBE suppression schemes tailoring to some specific practical needs.
Thin-walled boron nitride microtubes exhibiting intense band-edge UV emission at room temperature
NASA Astrophysics Data System (ADS)
Huang, Yang; Bando, Yoshio; Tang, Chengchun; Zhi, Chunyi; Terao, Takeshi; Dierre, Benjamin; Sekiguchi, Takashi; Golberg, Dmitri
Boron nitride (BN) microtubes were synthesized in a vertical induction furnace using Li2CO3 and B reactants. Their structures and morphologies were investigated using x-ray diffraction, scanning and transmission electron microscopy, and energy-dispersive x-ray spectroscopy. The microtubes have diameters of 1-3 Ąm, lengths of up to hundreds of micrometers, and well-structured ultrathin walls only ~50 nm thick. A mechanism combining the vapor-liquid-solid (VLS) and template self-sacrificing processes is proposed to explain the formation of these novel one-dimensional microstructures, in which the Li2O-B2O3 eutectic reaction plays an important role. Cathodoluminescence studies show that even at room temperature the thin-walled BN microtubes can possess an intense band-edge emission at ~216.5 nm, which is distinct compared with other BN nanostructures. The study suggests that the thin-walled BN microtubes should be promising for constructing compact deep UV devices and find potential applications in microreactors and microfluidic and drug delivery systems.
S-NPP VIIRS thermal emissive bands on-orbit calibration and performance
NASA Astrophysics Data System (ADS)
Efremova, Boryana; McIntire, Jeff; Moyer, David; Wu, Aisheng; Xiong, Xiaoxiong
Presented is an assessment of the on-orbit radiometric performance of the thermal emissive bands (TEB) of the Suomi National Polar-orbiting Partnership (S-NPP) Visible Infrared Imaging Radiometer Suite (VIIRS) instrument based on data from the first 2 years of operationsŚfrom 20 January 2012 to 20 January 2014. The VIIRS TEB are calibrated on orbit using a V-grooved blackbody (BB) as a radiance source. Performance characteristics trended over the life of the mission include the F factorŚa measure of the gain change of the TEB detectors; the Noise Equivalent differential Temperature (NEdT)Śa measure of the detector noise; and the detector offset and nonlinear terms trended at the quarterly performed BB warm-up cool-down cycles. We find that the BB temperature is well controlled and stable within the 30mK requirement. The F factor trends are very stable and showing little degradation (within 0.8%). The offsets and nonlinearity terms are also without noticeable drifts. NEdT is stable and does not show any trend. Other TEB radiometric calibration-related activities discussed include the on-orbit assessment of the response versus scan-angle functions and an approach to improve the M13 low-gain calibration using onboard lunar measurements. We conclude that all the assessed parameters comply with the requirements, and the TEB provide radiometric measurements with the required accuracy.
Crystal and electronic structures and high-pressure behavior of AgSO4, a unique narrow band gap antiferromagnetic semiconductor: LDA(+U) picture.
Derzsi, Mariana; Stasiewicz, Juliusz; Grochala, Wojciech
We demonstrate that DFT calculations performed with the local density approximation (LDA) allow for significantly better reproduction of lattice constants, the unit cell volume and the density of Ag(II)SO(4) than those done with generalized gradient approximation (GGA). The LDA+U scheme, which accounts for electronic correlation effects, enables the accurate prediction of the magnetic superexchange constant of this strongly correlated material and its band gap at the Fermi level. The character of the band gap places the compound on the borderline between a Mott insulator and a charge transfer insulator. The size of the band gap (0.82 eV) indicates that AgSO(4) is a ferrimagnetic semiconductor, and possibly an attractive material for spintronics. A bulk modulus of 27.0 GPa and a compressibility of 0.037 GPa(-1) were determined for AgSO(4) from the third-order Birch-Murnaghan isothermal equation of state up to 20 GPa. Several polymorphic types compete with the ambient pressure P-1 phase as the external pressure is increased. The P-1 phase is predicted to resist pressure-induced metallization up to at least 20 GPa. PMID:21267751
Narrow spectral emission CaMoO{sub 4}: Eu{sup 3+}, Dy{sup 3+}, Tb{sup 3+} phosphor crystals for white light emitting diodes
Khanna, A. [Smart Lighting Engineering Research Center, 110, 8th Street, Troy, New York, 12180 (United States) [Smart Lighting Engineering Research Center, 110, 8th Street, Troy, New York, 12180 (United States); Electrical, Computer and Systems Engineering Department, Rensselaer Polytechnic Institute, 110, 8th Street, Troy, New York, 12180 (United States); Dutta, P.S., E-mail: firstname.lastname@example.com [Smart Lighting Engineering Research Center, 110, 8th Street, Troy, New York, 12180 (United States); Electrical, Computer and Systems Engineering Department, Rensselaer Polytechnic Institute, 110, 8th Street, Troy, New York, 12180 (United States)
Alkaline earth metal molybdates are promising candidates as a host material for high efficiency narrow spectral emission phosphors. These phosphors could potentially be used for the fabrication of phosphor-converted light emitting diodes (pc-LEDs). Phosphor crystals of calcium molybdate doped with rare earth dopant Ln{sup 3+}(Ln=Eu, Dy, Tb) grown using flux growth method have been shown to exhibit higher excitation efficiency than the powders synthesized by solid-state reaction process. Molybdenum (VI) oxide has been found to be a suitable flux for growing large size optically transparent high quality crystals at a temperature around 1100 Degree-Sign C. Using the excitation wavelengths of 465 nm, 454 nm and 489 nm for CaMoO{sub 4}: Eu{sup 3+}, CaMoO{sub 4}: Dy{sup 3+} and CaMoO{sub 4}: Tb{sup 3+}, respectively, intense emission lines at wavelengths of 615 nm, 575 nm and 550 nm were observed. The optimized doping concentrations of 12%, 2% and 5% for Eu{sup 3+}, Dy{sup 3+} and Tb{sup 3+}, respectively, provided the highest luminescence intensity. - Graphical Abstract: CaMoO{sub 4}: Eu{sup 3+} phosphor crystals grown using a molybdenum (VI) oxide flux exhibited around 1.5 times the emission intensity of powders obtained from solid-state reaction at the same synthesis temperature. These crystals were found to efficiently emit 615 nm red light when excited by near UV light up to a wavelength of 395 nm. Highlights: Black-Right-Pointing-Pointer CaMoO{sub 4}: Ln{sup 3+} (Ln=Eu{sup 3+}, Dy{sup 3+}, Tb{sup 3+}) phosphor crystals were successfully grown using high temperature flux (solutions) containing molybdenum (VI) oxide or lithium chloride. Black-Right-Pointing-Pointer Narrow spectral emission at 615 nm, 575 nm and 550 nm, respectively, was observed from CaMoO{sub 4}: Ln{sup 3+} (Ln=Eu{sup 3+}, Dy{sup 3+}, Tb{sup 3+}) phosphor crystals. Black-Right-Pointing-Pointer The optimized doping concentrations of Eu{sup 3+}, Dy{sup 3+}, Tb{sup 3+} in CaMoO{sub 4} for highest emission intensity were determined to be 12%, 2% and 5%, respectively. Black-Right-Pointing-Pointer The CaMoO{sub 4}: Ln{sup 3+} (Ln=Eu{sup 3+}, Dy{sup 3+}, Tb{sup 3+}) phosphor crystals grown with molybdenum (VI) oxide flux exhibited 50% higher emission intensity compared to the crystals grown with lithium chloride flux and the powders synthesized by solid-state reaction.
Hydrogenation of polycyclic aromatic hydrocarbons as a factor affecting the cosmic 6.2 micron emission band
NASA Technical Reports Server (NTRS)
Beegle, L. W.; Wdowiak, T. J.; Harrison, J. G.
While many of the characteristics of the cosmic unidentified infrared (UIR) emission bands observed for interstellar and circumstellar sources within the Milky Way and other galaxies, can be best attributed to vibrational modes of the variants of the molecular family known as polycyclic aromatic hydrocarbons (PAH), there are open questions that need to be resolved. Among them is the observed strength of the 6.2 micron (1600 cm(-1)) band relative to other strong bands, and the generally low strength for measurements in the laboratory of the 1600 cm(-1) skeletal vibration band of many specific neutral PAH molecules. Also, experiments involving laser excitation of some gas phase neutral PAH species while producing long lifetime state emission in the 3.3 micron (3000 cm(-1)) spectral region, do not result in significant 6.2 micron (1600 cm(-1)) emission. A potentially important variant of the neutral PAH species, namely hydrogenated-PAH (H(N)-PAH) which exhibit intriguing spectral correlation with interstellar and circumstellar infrared emission and the 2175 A extinction feature, may be a factor affecting the strength of 6.2 micron emission. These species are hybrids of aromatic and cycloalkane structures. Laboratory infrared absorption spectroscopy augmented by density function theory (DFT) computations of selected partially hydrogenated-PAH molecules, demonstrates enhanced 6.2 micron (1600 cm(-1)) region skeletal vibration mode strength for these molecules relative to the normal PAH form. This along with other factors such as ionization or the incorporation of nitrogen or oxygen atoms could be a reason for the strength of the cosmic 6.2 micron (1600 cm(-1)) feature.
Design concepts for a high-impedance narrow-band 42 GHz power TWT using a fundamental/forward ladder-based circuit
NASA Technical Reports Server (NTRS)
Karp, A.
A low-cost, narrowband, millimeter wave space communications TWT design was studied. Cold test interaction structure scale models were investigated and analyses were undertaken to predict the electrical and thermal response of the hypothetical 200 W TWT at 42 GHz and 21 kV beam voltage. An intentionally narrow instantaneous bandwidth (1%, with the possibility of electronic tuning of the center frequency over several percent) was sought with a highly dispersive, high impedance "forward wave' interaction structure based on a ladder (for economy in fabrication) and nonspace harmonic interaction, for a high gain rate and a short, economically focused tube. The "TunneLadder' interaction structure devised combines ladder properties with accommodation for a pencil beam. Except for the impedance and bandwidth, there is much in common with the millimeter wave helix TWTs which provided the ideal of diamond support rods. The benefits of these are enhanced in the TunneLadder case because of spatial separation of beam interception and RF current heating.
VLT/X-shooter spectroscopy of SN 2009ip: Narrow + intermediate width emission lines and NIR excess emission relative to a black body
NASA Astrophysics Data System (ADS)
Gall, Christa; Hjorth, Jens; Leloudas, Giorgos
The recent outburst of the LBV SN 2009ip is likely a genuine Type IIn supernova (Smith & Mauerhan ATel #4412, ATel #4427, Mauerhan et al. arXiv:1209.6320). We observed the transient with the X-shooter spectrograph (Vernet et al. 2011, A&A, 536, A105) at the VLT on 2012 September 30.03 UT, covering the wavelength range 320 nm to 2400 nm, at a resolving power ranging from 5100 to 8800. The spectrum shows a richness of prominent hydrogen emission lines from the Balmer and Paschen series as well as Bracket gamma.
L-Band H Polarized Microwave Emission During the Corn Growth Cycle
NASA Technical Reports Server (NTRS)
Joseph, A. T.; va der Velde, R.; O'Neill, P. E.; Kim, E.; Lang, R. H.; Gish, T.
Hourly L-band (1.4 GHz) horizontally (H) polarized brightness temperatures (T(sub B))'s measured during five episodes (more than two days of continuous measurements) of the 2002 corn growth cycle are analyzed. These T(sub B)'s measurements were acquired as a part of a combined active/passive microwave field campaign, and were obtained at five incidence and three azimuth angles relative to the row direction. In support of this microwave data collection, intensive ground sampling took place once a week. Moreover, the interpretation of the hourly T(sub B)'s could also rely on the data obtained using the various automated instruments installed in the same field. In this paper, the soil moisture and temperature measured at fixed time intervals have been employed as input for the tau-omega model to reproduce the hourly T(sub B). Through the calibration of the vegetation and surface roughness parameterizations, the impact of the vegetation morphological changes on the microwave emission and the dependence of the soil surface roughness parameter, h(sub r), on soil moisture are investigated. This analysis demonstrates that the b parameter, appearing in the representation of the canopy opacity, has an angular dependence that varies throughout the growing period and also that the parameter hr increases as the soil dries in a portion of the dry-down cycle. The angular dependence of the b parameter imposes the largest uncertainty on T(sub B) simulations near senescence as the response of b to the incidence is also affected by the crop row orientation. On the other hand, the incorporation of a soil moisture dependent h(sub r) parameterization was responsible for the largest error reduction of T(sub B) simulations in the early growth cycle.
Methane oxidation behind reflected shock waves: Ignition delay times measured by pressure and flame band emission
NASA Technical Reports Server (NTRS)
Brabbs, T. A.; Robertson, T. F.
Ignition delay data were recorded for three methane-oxygen-argon mixtures (phi = 0.5, 1.0, 2.0) for the temperature range 1500 to 1920 K. Quiet pressure trances enabled us to obtain delay times for the start of the experimental pressure rise. These times were in good agreement with those obtained from the flame band emission at 3700 A. The data correlated well with the oxygen and methane dependence of Lifshitz, but showed a much stronger temperature dependence (phi = 0.5 delta E = 51.9, phi = 1.0 delta = 58.8, phi = 2.0 delta E = 58.7 Kcal). The effect of probe location on the delay time measurement was studied. It appears that the probe located 83 mm from the reflecting surface measured delay times which may not be related to the initial temperature and pressure. It was estimated that for a probe located 7 mm from the reflecting surface, the measured delay time would be about 10 microseconds too short, and it was suggested that delay times less than 100 microsecond should not be used. The ignition period was defined as the time interval between start of the experimental pressure rise and 50 percent of the ignition pressure. This time interval was measured for three gas mixtures and found to be similar (40 to 60 micro sec) for phi = 1.0 and 0.5 but much longer (100 to 120) microsecond for phi = 2.0. It was suggested that the ignition period would be very useful to the kinetic modeler in judging the agreement between experimental and calculated delay times.
Evaluation of Terra and Aqua MODIS thermal emissive band response versus scan angle
NASA Astrophysics Data System (ADS)
Wenny, B. N.; Wu, A.; Madhavan, S.; Xiong, X.
Terra and Aqua MODIS have operated near-continuously for over 14 and 12 years, respectively, and are key instruments for NASA's Earth Observing System. Observations from the 16 thermal emissive bands (TEB), covering wavelengths from 3.5 to 14.4 ?m with a nadir spatial resolution of 1 km are used to regularly generate a variety of atmosphere, ocean and land science products. The TEB detectors are calibrated using scan-by-scan observations of an on-board blackbody (BB). The current response versus scan angle (RVS) of the scan mirror was derived using a spacecraft deep-space pitch maneuver for Terra MODIS and characterized during prelaunch for Aqua MODIS. Earth view (EV) data over the complete range of angles of incidence (AOI) can be used to evaluate the on-orbit performance of the TEB RVS over the mission lifetime. Three approaches for tracking the TEB RVS on-orbit using EV observations are formulated. The first approach uses the multiple daily observations of Dome C BT at different AOI and their trend relative to coincident measurements from a ground temperature sensor. The second approach uses brightness temperatures (BT) retrieved over the cloud-free ocean to derive the trends at 13 AOI over the mission lifetime. The third approach tracks the dn response (normalized to the BB AOI) across the full swath width for Antarctic granules with the Dome C site at nadir. The viability of the three approaches is assessed and the long-term stability of the TEB RVS for both MODIS instruments is determined.
DETECTION OF K{sub S} -BAND THERMAL EMISSION FROM WASP-3b
Zhao Ming; Wright, Jason [Department of Astronomy and Astrophysics, 525 Davey Laboratory, Pennsylvania State University, University Park, PA 16802 (United States); Milburn, Jennifer; Hinkley, Sasha [Department of Astronomy, California Institute of Technology, Pasadena, CA 91009 (United States); Barman, Travis [Lowell Observatory, 1400 West Mars Hill Road, Flagstaff, AZ 86001 (United States); Swain, Mark R. [Jet Propulsion Lab, California Institute of Technology, Pasadena, CA 91009 (United States); Monnier, John D., E-mail: email@example.com [Department of Astronomy, University of Michigan, Ann Arbor, MI 48104 (United States)
We report the detection of thermal emission from the hot Jupiter WASP-3b in the K{sub S} band, using a newly developed guiding scheme for the WIRC instrument at the Palomar Hale 200 inch telescope. Our new guiding scheme has improved the telescope guiding precision by a factor of {approx}5-7, significantly reducing the correlated systematics in the measured light curves. This results in the detection of a secondary eclipse with depth of 0.181% {+-} 0.020% (9{sigma})-a significant improvement in WIRC's photometric precision and a demonstration of the capability of Palomar/WIRC to produce high-quality measurements of exoplanetary atmospheres. Our measured eclipse depth cannot be explained by model atmospheres with heat redistribution but favors a pure radiative equilibrium case with no redistribution across the surface of the planet. Our measurement also gives an eclipse phase center of 0.5045 {+-} 0.0020, corresponding to an ecos {omega} of 0.0070 {+-} 0.0032. This result is consistent with a circular orbit, although it also suggests that the planet's orbit might be slightly eccentric. The possible non-zero eccentricity provides insight into the tidal circularization process of the star-planet system, but might also have been caused by a second low-mass planet in the system, as suggested by a previous transit timing variation study. More secondary eclipse observations, especially at multiple wavelengths, are necessary to determine the temperature-pressure profile of the planet's atmosphere and shed light on its orbital eccentricity.
Estimating net rainfall, evaporation and water storage of a bare soil from sequential L-band emissivities
NASA Technical Reports Server (NTRS)
Stroosnijder, L.; Lascano, R. J.; Newton, R. W.; Vanbavel, C. H. M.
A general method to use a time series of L-band emissivities as an input to a hydrological model for continuously monitoring the net rainfall and evaporation as well as the water content over the entire soil profile is proposed. The model requires a sufficiently accurate and general relation between soil emissivity and surface moisture content. A model which requires the soil hydraulic properties as an additional input, but does not need any weather data was developed. The method is shown to be numerically consistent.
Strong interactions, narrow bands, and dominant spin-orbit coupling in Mott insulating quadruple perovskite CaCo3V4O12
NASA Astrophysics Data System (ADS)
Rhee, H. B.; Pickett, W. E.
We investigate the electronic and magnetic structures and the character and direction of spin and orbital moments of the recently synthesized quadruple perovskite compound CaCo3V4O12 using a selection of methods from density functional theory. Implementing the generalized gradient approximation and the Hubbard U correction (GGA+U ), ferromagnetic spin alignment leads to half-metallicity rather than the observed narrow gap insulating behavior. Including spin-orbit coupling (SOC) leaves a Mott insulating spectrum but with a negligible gap. SOC is crucial for the Mott insulating character of the V d1 ion, breaking the dm =▒1 degeneracy and also giving a substantial orbital moment. Evidence is obtained of the large orbital moments on Co that have been inferred from the measured susceptibility. Switching to the orbital polarization (OP) functional, GGA+OP+SOC also displays clear tendencies toward very large orbital moments but in its own distinctive manner. In both approaches, application of SOC, which requires specification of the direction of the spin, introduces large differences in the orbital moments of the three Co ions in the primitive cell. We study a fictitious but simpler cousin compound Ca3CoV4O12 (Ca replacing two of the Co atoms) to probe in a more transparent fashion the interplay of spin and orbital degrees of freedom with the local environment of the planar CoO4 units. The observation is made that the underlying mechanisms seem to be local to a CoO4 plaquette, and that there is very strong coupling of the size of the orbital moment to the spin direction. These facts strongly suggest noncollinear spins, not only on Co but on the V sublattice as well.
Broad emission band of Yb3+ in the nonlinear Nb:RbTiOPO4 crystal: origin and applications.
Carvajal, J J; Ciatto, G; Mateos, X; Schmidt, A; Griebner, U; Petrov, V; Boulon, G; Brenier, A; Pe±a, A; Pujol, M C; Aguil¾, M; DĒaz, F
By means of micro-structural and optical characterization of the Yb:Nb:RbTiOPO(4) crystal, we demonstrated that the broad emission band of Yb(3+) in these crystals is due to the large splitting of the ytterbium ground state only, and not to a complex multisite occupation by the ytterbium ions in the crystals. We used this broad emission band to demonstrate wide laser tuning range and generation of femtosecond laser pulses. Passive mode-locked laser operation has been realized by using a semiconductor saturable absorber mirror, generating ultra short laser pulses of 155 fs, which were very stable in time, under Ti:sapphire laser pumping at 1053 nm. PMID:20389744
Sea Ice Emissivity Modeling at L-Band and Application to 2007 PolIce Campaign Field Data
Peter Mills; Georg Heygster
Sea ice emissivity models for the L-band frequency range are described and then tested on Pol-Ice campaign field measurements. Pol-Ice was conducted in March 2007 in the North- ern Baltic in preparation for the launch of the Soil Moisture and Ocean Salinity (SMOS) instrument, a satellite microwave radiometer operating at 1.4 GHz. The campaign comprised air- borne measurements from the
Space Telescope Imaging Spectrograph Long-Slit Spectroscopy of the Narrow-Line Region of NGC 4151. 1; Kinematics and Emission-Line Ratios
NASA Technical Reports Server (NTRS)
Nelson, C. H.; Weistrop, D.; Hutchinson, J. B.; Crenshaw, D. M.; Gull, T. R.; Kaiser, M. E.; Kraemer, S. B.; Lindler, D.
Long-slit spectra of the Seyfert galaxy NGC 4151 from the UV to the near-infrared have been obtained with the Space Telescope Imaging Spectrograph (STIS) to study the kinematics and physical conditions in the narrow-line region (NLR). The kinematics shows evidence for three components, a low-velocity system in normal disk rotation, a high-velocity system in radial outflow at a few hundred kilometers per second relative to the systemic velocity, and an additional high-velocity system also in outflow with velocities up to 1400 km s(-l), in agreement with results from STIS slitless spectroscopy. We have explored two simple kinematic models and suggest that radial outflow in the form of a wind is the most likely explanation. We also present evidence indicating that the wind may be decelerating with distance from the nucleus. We find that the emission-line ratios along our slits are all entirely consistent with photoionization from the nuclear continuum source. A decrease in the ratios [O III] lambda 5007/H beta and [O III] lambda 5007/[O II] lambda 3727 suggests that the density decreases with distance from the nucleus. This trend is borne out by the [S II] ratios as well. We find no strong evidence for interaction between the radio jet and the NLR gas in either the kinematics or the emission-line ratios, in agreement with the recent results of Kaiser et al., who found no spatial coincidence of NLR clouds and knots in the radio jet. These results are in contrast to other recent studies of nearby active galactic nuclei that find evidence for significant interaction between the radio source and the NLR gas.
Interstellar polycyclic aromatic hydrocarbons - The infrared emission bands, the excitation\\/emission mechanism, and the astrophysical implications
L. J. Allamandola; G. G. M. Tielens; J. R. Barker
A comprehensive study of the PAH hypothesis is presented, including the interstellar, IR spectral features which have been attributed to emission from highly vibrationally excited PAHs. Spectroscopic and IR emission features are discussed in detail. A method for calculating the IR fluorescence spectrum from a vibrationally excited molecule is described. Analysis of interstellar spectrum suggests that the PAHs which dominate
Doi, Akihiro [The Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuou-ku, Sagamihara, Kanagawa 252-5210 (Japan)] [The Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuou-ku, Sagamihara, Kanagawa 252-5210 (Japan); Asada, Keiichi; Inoue, Makoto [Academia Sinica Institute of Astronomy and Astrophysics, P.O. Box 23-141, Taipei 10617, Taiwan (China)] [Academia Sinica Institute of Astronomy and Astrophysics, P.O. Box 23-141, Taipei 10617, Taiwan (China); Fujisawa, Kenta [The Research Institute of Time Studies, Yamaguchi University, 1677-1 Yoshida, Yamaguchi, Yamaguchi 753-8511 (Japan)] [The Research Institute of Time Studies, Yamaguchi University, 1677-1 Yoshida, Yamaguchi, Yamaguchi 753-8511 (Japan); Nagai, Hiroshi; Hagiwara, Yoshiaki [National Astronomical Observatory, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)] [National Astronomical Observatory, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Wajima, Kiyoaki, E-mail: firstname.lastname@example.com [Shanghai Astronomical Observatory, Chinese Academy of Sciences, Shanghai 200030 (China)] [Shanghai Astronomical Observatory, Chinese Academy of Sciences, Shanghai 200030 (China)
We conducted Very Long Baseline Array (VLBA) observations of seven nearby narrow-line Seyfert 1 (NLS1) galaxies at 1.7 GHz ({lambda}18 cm) with milliarcsecond resolution. This is the first systematic very long baseline interferometry study focusing on the central parsec-scale regions of radio-quiet NLS1s. Five of the seven were detected at a brightness temperature of {approx}> 5 Multiplication-Sign 10{sup 6} K and contain radio cores with high brightness temperatures of >6 Multiplication-Sign 10{sup 7} K, indicating a nonthermal process driven by jet-producing central engines as in radio-loud NLS1s and other active galactic nucleus classes. VLBA images of MRK 1239, MRK 705, and MRK 766 exhibit parsec-scale jets with clear linear structures. A large portion of the radio power comes from diffuse emission components that are distributed within the nuclear regions ({approx}< 300 pc), which is a common characteristic throughout the observed NLS1s. Jet kinetic powers limited by the Eddington limit may be insufficient to allow the jets to escape to kiloparsec scales for these radio-quiet NLS1s with low-mass black holes of {approx}< 10{sup 7} M {sub Sun }.
Coupling of narrow and wide band-gap semiconductors on uniform films active in bacterial disinfection under low intensity visible light: implications of the interfacial charge transfer (IFCT).
Rtimi, S; Sanjines, R; Pulgarin, C; Houas, A; Lavanchy, J-C; Kiwi, J
This study reports the design, preparation, testing and surface characterization of uniform films deposited by sputtering Ag and Ta on non-heat resistant polyester to evaluate the Escherichia coli inactivation by TaON, TaN/Ag, Ag and TaON/Ag polyester. Co-sputtering for 120 s Ta and Ag in the presence of N? and O? led to the faster E. coli inactivation by a TaON/Ag sample within ?40 min under visible light irradiation. The deconvolution of TaON/Ag peaks obtained by X-ray photoelectron spectroscopy (XPS) allowed the assignment of the Ta?O? and Ag-species. The shifts observed for the XPS peaks have been assigned to AgO to Ag?O and Ag(0), and are a function of the applied sputtering times. The mechanism of interfacial charge transfer (IFCT) from the Ag?O conduction band (cb) to the lower laying Ta?O? (cb) is discussed suggesting a reaction mechanism. The optical absorption of the TaON and TaON/Ag samples found by diffuse reflectance spectroscopy (DRS) correlated well with the kinetics of E. coli inactivation. The TaON/Ag sample microstructure was characterized by contact angle (CA) and by atomic force microscopy (AFM). Self-cleaning of the TaON/Ag polyester after each disinfection cycle enabled repetitive E. coli inactivation. PMID:23867967
Wavelength Shifts of the 7.7 Micron Emission Band in Reflection Nebulae
NASA Technical Reports Server (NTRS)
Bregman, Jesse; Temi, Pasquale
Using spatial-spectral data cubes of reflection nebulae obtained by ISOCAM, we have observed a shift in the central wavelength of the 7.7 micron band within several reflection nebulae. The band shifts progressively from approx. 7.8 microns near the edge of the nebulae to approx. 7.6 microns towards the center of the nebulae. The ratio of the 11.3/7.7 micron bands also changes with distance from the central star, first rising from the center towards the edge of the nebula, then falling at the largest distances from the star, consistent with the 11.3/7.7 micron band ratio being controlled by the PAH ionization state. The behavior of the 7.7 micron band center can be explained either by assuming that anions are the origin of the 7.85 micron band and cations the 7.65 micron band, or that the band center wavelength depends on the chemical nature of the PAHs.
Acoustic emissions and porosity reduction during growth of discrete compaction bands in porous sandstone
P. Baud; P. Meredith; S. Boon
Recent field and laboratory studies have documented the occurrence of strain localisation in porous sandstones. The localised failure mode can be in shear or compaction, in the form of conjugate shear or compaction bands oriented at relatively high angles to the maximum compression direction. Compaction bands in particular have drawn a lot of interest because these localized structures could potentially
Laboratory studies of UV emissions of H2 by electron impact - The Werner- and Lyman-band systems
NASA Technical Reports Server (NTRS)
Ajello, J. M.; Srivastava, S. K.; Yung, Y. L.
The vacuum ultraviolet electron-impact-induced fluorescence emissions of H2 were studied for the Lyman and Werner band systems in the range of 120-170 nm, using an optical system containing a photomultiplier and a spectrometer, over an energy range from threshold to 400 eV. The emission cross sections for the Lyman and Werner transitions at 100 eV are determined. The cross-section ratio is in excellent agreement with theoretical calculations and experimental data for the optical oscillator strengths. The cross-section for cascading to the B state is stated as a percentage of the total emission cross section at both 100 and 300 eV, increasing substantially at 20 eV. The vibrational population distribution of the B state is found to be a function of electron-impact energy as the importance of cascading relative to direct excitation changes with electron-impact energy.
Impact of Si nanocrystals in a-SiOx in C-Band emission for applications in resonators structures
Figueira, D S L; Tessler, L R; Frateschi, N C
Si nanocrystals (Si-NC) in a-SiOx were created by high temperature annealing. Si-NC samples have large emission in a broadband region, 700nm to 1000nm. Annealing temperature, annealing time, substrate type, and erbium concentration is studied to allow emission at 1550 nm forsamples with erbium. Emission in the C-Band region is largely reduced by the presence of Si-NC. This reduction may be due to less efficient energy transfer processes from the nanocrystals than from the amorphous matrix to the Er3+ ions, perhaps due to the formation of more centro-symmetric Er3+ sites at the nanocrystal surfaces or to very different optimal erbium concentrations between amorphous and crystallized samples.
Effect of multiple conduction bands on high-harmonic emission from dielectrics
NASA Astrophysics Data System (ADS)
Hawkins, Peter G.; Ivanov, Misha Yu.; Yakovlev, Vladislav S.
We find that, for sufficiently strong mid-IR fields, transitions between different conduction bands play an important role in the generation of high-order harmonics in a dielectric. The transitions make a significant contribution to the harmonic signal, and they can create a single effective band for the motion of an electron wave packet. We show how high harmonic spectra produced during the interaction of ultrashort laser pulses with periodic solids provide a spectroscopic tool for understanding the effective band structure that controls electron dynamics in these media.
The ALI-ARMS Code for Modeling Atmospheric non-LTE Molecular Band Emissions: Current Status and Applications
NASA Technical Reports Server (NTRS)
Kutepov, A. A.; Feofilov, A. G.; Manuilova, R. O.; Yankovsky, V. A.; Rezac, L.; Pesnell, W. D.; Goldberg, R. A.
The Accelerated Lambda Iteration (ALI) technique was developed in stellar astrophysics at the beginning of 1990s for solving the non-LTE radiative transfer problem in atomic lines and multiplets in stellar atmospheres. It was later successfully applied to modeling the non-LTE emissions and radiative cooling/heating in the vibrational-rotational bands of molecules in planetary atmospheres. Similar to the standard lambda iterations ALI operates with the matrices of minimal dimension. However, it provides higher convergence rate and stability due to removing from the iterating process the photons trapped in the optically thick line cores. In the current ALI-ARMS (ALI for Atmospheric Radiation and Molecular Spectra) code version additional acceleration of calculations is provided by utilizing the opacity distribution function (ODF) approach and "decoupling". The former allows replacing the band branches by single lines of special shape, whereas the latter treats non-linearity caused by strong near-resonant vibration-vibrational level coupling without additional linearizing the statistical equilibrium equations. Latest code application for the non-LTE diagnostics of the molecular band emissions of Earth's and Martian atmospheres as well as for the non-LTE IR cooling/heating calculations are discussed.
THE 217.5 nm BAND, INFRARED ABSORPTION, AND INFRARED EMISSION FEATURES IN HYDROGENATED AMORPHOUS CARBON NANOPARTICLES
Duley, W. W. [Department of Physics and Astronomy, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1 (Canada)] [Department of Physics and Astronomy, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1 (Canada); Hu, Anming, E-mail: email@example.com, E-mail: email@example.com [Department of Mechanical and Mechatronics Engineering, Centre for Advanced Material Joining, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1 (Canada)] [Department of Mechanical and Mechatronics Engineering, Centre for Advanced Material Joining, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1 (Canada)
We report on the preparation of hydrogenated amorphous carbon nanoparticles whose spectral characteristics include an absorption band at 217.5 nm with the profile and characteristics of the interstellar 217.5 nm feature. Vibrational spectra of these particles also contain the features commonly observed in absorption and emission from dust in the diffuse interstellar medium. These materials are produced under ''slow'' deposition conditions by minimizing the flux of incident carbon atoms and by reducing surface mobility. The initial chemistry leads to the formation of carbon chains, together with a limited range of small aromatic ring molecules, and eventually results in carbon nanoparticles having an sp {sup 2}/sp {sup 3} ratio Almost-Equal-To 0.4. Spectroscopic analysis of particle composition indicates that naphthalene and naphthalene derivatives are important constituents of this material. We suggest that carbon nanoparticles with similar composition are responsible for the appearance of the interstellar 217.5 nm band and outline how these particles can form in situ under diffuse cloud conditions by deposition of carbon on the surface of silicate grains. Spectral data from carbon nanoparticles formed under these conditions accurately reproduce IR emission spectra from a number of Galactic sources. We provide the first detailed fits to observational spectra of Type A and B emission sources based entirely on measured spectra of a carbonaceous material that can be produced in the laboratory.
Emission Bands of the Fluctuation Type in the Spectrum of Iodine
R. K. Asundi; P. Venkateswarlu
As part of an investigation undertaken in this laboratory on the emission spectra of halogens and halogen derivatives of methane1, the emission spectrum of iodine is being studied. The spectrum is excited by a high-frequency as well as a transformer discharge in iodine vapour of pressure equivalent to the saturated vapour pressure of iodine at room temperature. A Steinheil 3-prism
Production of N2 Vegard-Kaplan and other triplet band emissions in the dayglow of Titan
NASA Astrophysics Data System (ADS)
Bhardwaj, Anil; Jain, Sonal Kumar
Recently the Cassini Ultraviolet Imaging Spectrograph (UVIS) has revealed the presence of N2 Vegard-Kaplan (VK) band A3?u+-X1?g+ emissions in Titan's dayglow limb observation. We present model calculations for the production of various N2 triplet states (viz., A3?u+,B3?g,C3?u,E3?u,W3?u, and B3?u ) in the upper atmosphere of Titan. The Analytical Yield Spectra technique is used to calculate steady state photoelectron fluxes in Titan's atmosphere, which are in agreement with those observed by the Cassini's CAPS instrument. Considering direct electron impact excitation, inter-state cascading, and quenching effects, the population of different levels of N2 triplet states are calculated under statistical equilibrium. Densities of all vibrational levels of each triplet state and volume production rates for various triplet states are calculated in the model. Vertically integrated overhead intensities for the same date and lighting conditions as reported by the UVIS observations for N2 Vegard-Kaplan A3?u+-X1?g+, First Positive B3?g-A3?u+, Second Positive (C3?u - B3?g), Wu-Benesch (W3?u - B3?g), and Reverse First Positive bands of N2 are found to be 132, 114, 19, 22, and 22 R, respectively. Overhead intensities are calculated for each vibrational transition of all the triplet band emissions of N2, which span a wider spectrum of wavelengths from ultraviolet to infrared. The calculated limb intensities of total and prominent transitions of VK band are presented. The model limb intensity of VK emission within the 150-190 nm wavelength region is in good agreement with the Cassini UVIS observed limb profile. An assessment of the impact of solar EUV flux on the N2 triplet band emission intensity has been made by using three different solar flux models, viz., Solar EUV Experiment (SEE), SOLAR2000 (S2K) model of Tobiska (Tobiska, W.K. [2004]. Adv. Space Res. 34, 1736-1746), and HEUVAC model of Richards et al. (Richards, P.G., Woods, T.N., Peterson, W.K. [2006]. Adv. Space Res. 37 (2), 315-322). The calculated N2 VK band intensity at the peak of limb intensity due to S2K and HEUVAC solar flux models is a factor of 1.2 and 0.9, respectively, of that obtained using SEE solar EUV flux. The effects of higher N2 density and solar zenith angle on the emission intensity are also studied. The model predicted N2 triplet band intensities during moderate (F10.7 = 150) and high (F10.7 = 240) solar activity conditions, using SEE solar EUV flux, are a factor of 2 and 2.8, respectively, higher than those during solar minimum (F10.7 = 68) condition.
L & M band infrared studies of V4332 Sagittarii - detection of the water-ice absorption band at 3.05 microns and the CO fundamental band in emission
Dipankar P. K. Banerjee; Watson P. Varricatt; Nagarhalli M. Ashok
L and M band observations of the nova-like variable V4332 Sgr are presented. Two significant results are obtained viz. the unusual detection of water ice at 3.05 microns and the fundamental band of 12CO at 4.67 microns in emission. The ice feature is a first detection in a nova-like variable while the CO emission is rarely seen in novae. These results, when considered together with other existing data, imply that V4332 Sgr could be a young object surrounded by a circumstellar disc containing gas, dust and ice. The reason for a nova-like outburst to occur in such a system is unclear. But since planets are believed to form in such disks, it appears plausible that the enigmatic outburst of V4332 Sgr could be due to a planetary infall. We also give a more reliable estimate for an epoch of dust formation around V4332 Sgr which appears to have taken place rather late in 1999 - nearly five years after its outburst.
The 4.8 and 9.6-micron O3 band emissions in the middle atmosphere
NASA Astrophysics Data System (ADS)
Manuilova, R. O.; Shved, G. M.
For the 40-115 km atmospheric layer, the populations of 19 vibrational states of the O3 molecule have been calculated for sets of vertical profiles of temperature and concentration of O and O3. A peculiar feature of the day and nighttime vertical profiles of the vibrational temperature of the states is at its maximum in the height range 75-90 km which is due to the formation of vibrationally excited molecules of O3 in the recombination: O2 + O + M yields O3 + M. On the basis of the calculated populations of the states, the limb and downward atmospheric emissions in the 4.8 and 9.6-micron O3 bands have been estimated, as well as the contributions of the constituents of the band of vibrational transitions.
A Search for Disk Emission in Young Brown Dwarfs: L'-band Observations of sigma Orionis and TW Hydrae
Ray Jayawardhana; David R. Ardila; Beate Stelzer
Studies of disks around young brown dwarfs are of paramount importance to our understanding of the origin, diversity and early evolution of sub-stellar objects. Here we present first results from a systematic search for disk emission in a spectroscopically confirmed sample of young objects near or below the sub-stellar boundary in a variety of star-forming regions. Our VLT and Keck L'-band observations of the sigma Orionis and TW Hydrae associations suggest that if a majority of brown dwarfs are born with disks, at least the inner regions of those disks evolve rapidly, possibly clearing out within a few million years.
Tuning the light emission properties by band gap engineering in hybrid lead halide perovskite.
D'Innocenzo, Valerio; Srimath Kandada, Ajay Ram; De Bastiani, Michele; Gandini, Marina; Petrozza, Annamaria
We report about the relationship between the morphology and luminescence properties of methylammonium lead trihalide perovskite thin films. By tuning the average crystallite dimension in the film from tens of nanometers to a few micrometers, we are able to tune the optical band gap of the material along with its photoluminescence lifetime. We demonstrate that larger crystallites present smaller band gap and longer lifetime, which correlates to a smaller radiative bimolecular recombination coefficient. We also show that they present a higher optical gain, becoming preferred candidates for the realization of CW lasing devices. PMID:25469762
Beyond the Band Function Paradigm : a New Model for GRB Prompt Emission and Possible Impact in Cosmology
NASA Astrophysics Data System (ADS)
Guiriec, Sylvain
Gamma Ray Bursts (GRBs) are the most violent phenomenons in the Universe. They are associated with the birth of stellar mass black holes either from the collapse of hypermassive stars or the merger of compact objects. The Fireball model is the most popular scenario to explain GRBs. In this theoretical framework, GRB central engines release collimated, bipolar and highly relativistic jets mainly composed of electrons, positrons, photons, and a small amount of baryons. During the first phase of the Fireball model, charged particles are accelerated and release non-thermal radiations. The Fireball model also predicts a thermal like component coming from the jet photosphere. This first phase would be responsible for the GRB prompt emission observed by gamma ray telescopes such as Fermi/GBM in the keV-MeV energy range and which is the only phase discussed in this talk. Until now, GRB prompt emission spectra were considered as adequately fitted with the empirical Band function, which is a smoothly broken power law. However, its parameters are very often incompatible with the Fireball model predictions for both the thermal and non-thermal components. We will see that observation with the Fermi Gamma Ray Space Telescope break the paradigm of the Band function and that deviations from this function exists in many GRBs. Those deviations are adequately fitted with an additional thermal-like component -that we consider as the jet photosphere- and/or an additional power law. Importantly, with the three components together, theory and observations are much more in agreement. We will also see how this new model for prompt emission spectra may have an impact beyond the physics of GRBs. Indeed, this work may confirm a relation between the hardness of the GRB prompt emission and its luminosity which may be used to scale GRBs as standard-like candles for use in cosmology.
DAY-SIDE z ?-BAND EMISSION AND ECCENTRICITY OF WASP-12b
L¾pez-Morales, Mercedes
We report the detection of the eclipse of the very hot Jupiter WASP-12b via z'-band time-series photometry obtained with the 3.5 m Astrophysical Research Consortium telescope at Apache Point Observatory. We measure a ...
Lugol chromo-endoscopy versus narrow band imaging for endoscopic screening of esophageal squamous-cell carcinoma in patients with a history of cured esophageal cancer: a feasibility study.
Lecleire, S; Antonietti, M; Iwanicki-Caron, I; Duclos, A; Lemoine, F; Pessot, F L; Michel, P; Ducrottķ, P; Di Fiore, F
To date, Lugol chromo-endoscopy is the reference technique to detect an esophageal neoplasia in patients with prior esophageal squamous-cell carcinoma (ESCC), but is not easy to perform without general anesthesia, which can limit its use in routine practice. The objective of this study were to compare the accuracy of white light, narrow band imaging (NBI), and Lugol to detect esophageal neoplasia in patients with a history of cured ESCC, in a prospective study. Thirty patients were prospectively included between June 2006 and June 2009. They all had a history of cured ESCC. Esophageal mucosa was examined first using white light, second NBI, and third after Lugol staining. Histology was obtained in all abnormalities detected by white light, NBI, and/or Lugol. Five neoplastic lesions in five different patients were identified at histology, four cancers, and one high-grade dysplasia. NBI and Lugol both detected all esophageal neoplastic lesions, whereas white light detected the four cancers but missed the high-grade dysplasia. In this feasibility study, NBI and Lugol both detected all identified esophageal neoplasia in very high-risk patients of ESCC. This result suggests that NBI could be used instead of Lugol to detect an esophageal neoplasia in patients with high risk of ESCC, but needs to be confirmed in a larger study. PMID:21309914
Synchrotron studies of narrow band materials
Not Available
Since last year, we have had three 3-week blocks of beamtime, in April and November 1991 and February 1992, on the Ames/Montana beamline at the Wisconsin Synchrotron Radiation Center (SRC). These runs continued our program on high temperature superconductors, heavy Fermion and related uranium and rare earth materials, and started some work on transition metal oxides. We have also had beamtime at the Brookhaven NSLS, 5 days of beamtime on the Dragon monochromator, beamline U4B, studying resonant photoemission of transition metal oxides using photon energies around the transition metal 2p edges. Data from past runs has been analyzed, and in some cases combined with photoemission and bremsstrahlung isochromat spectroscopy (BIS) data taken in the home U-M lab. 1 fig.
Orbital polarization in narrow band systems
Eriksson, O.; Johansson, B.; Brooks, M.S..S. (Uppsala Univ. (Sweden). Inst. of Physics; Commission of the European Communities, Karlsruhe (Germany, F.R.). European Inst. for Transuranium Elements)
A novel technique for treating orbital polarization is presented. The single electron eigenvalue shifts that emanates from the orbital polarization is of the form -E{sup 3}Lm{sub l}, where E{sup 3} is the Racah parameter, L is the orbital moment and m{sub l} the azimuthal quantum number. Thereby the effect of Hund's second rule is included not only in the total energy, but also in the eigenvalue splittings which are required in the solid. The calculations presented also incorporate the exchange and correlation potential in the local spin density approximation as well as the spin-orbit coupling. The self-consistently calculated equation-of-state for the light lanthanide Ce is presented. The observed volume collapse is well described by the parameter free calculations and accordingly the volume collapse in Ce is described as a Mott transition of the 4f electron. 20 refs., 1 fig., 1 tab.
Band-gap evolution, hybridization, and thermal stability of InxGa1-xN alloys measured by soft X-ray emission and absorption
NASA Astrophysics Data System (ADS)
Ryan, Philip; McGuinness, Cormac; Downes, James E.; Smith, Kevin E.; Doppalapudi, Dharanipal; Moustakas, Theodore D.
The electronic structure of InxGa1-xN alloys with (0<=x<=0.3) has been studied using synchrotron radiation excited soft x-ray emission and absorption spectroscopies. These spectroscopies allow the elementally resolved partial density of states of the valence and conduction bands to be measured. The x-ray absorption spectra indicate that the conduction band broadens considerably with increasing indium incorporation. The evolution of the band gap as a function of indium content derives primarily from this broadening of the conduction-band states. The emission spectra indicate that motion of the valence band makes a smaller contribution to the evolution of the band gap. This gap evolution differs from previous studies on the AlxGa1-xN alloy system, which observed a linear valence-band shift through the series (0<=x<=1). For InxGa1-xN the valence band exhibits a large shift between x=0 and x=0.1 with minimal movement thereafter. We also report evidence of In 4d-N 2p and Ga 3d-N 2p hybridization. Finally, the thermal stability of an In0.11Ga0.89N film was investigated. Both emission and absorption spectra were found to have a temperature-dependent shift in energy, but the overall definition of the spectra was unaltered even at annealing temperatures well beyond the growth temperature of the film.
Soil moisture, dielectric permittivity and emissivity of soil: effective depth of emission measured by the L-band radiometer ELBARA
NASA Astrophysics Data System (ADS)
Usowicz, Boguslaw; Lukowski, Mateusz; Marczewski, Wojciech; Usowicz, Jerzy; Lipiec, Jerzy; Rojek, Edyta; Slominska, Ewa; Slominski, Jan
Due to the large variation of soil moisture in space and in time, obtaining soil water balance with an aid of data acquired from the surface is still a challenge. Microwave remote sensing is widely used to determine the water content in soil. It is based on the fact that the dielectric constant of the soil is strongly dependent on its water content. This method provides the data in both local and global scales. Very important issue that is still not solved, is the soil depth at which radiometer "sees" the incoming radiation and how this "depth of view" depends on water content and physical properties of soil. The microwave emission comes from its entire profile, but much of this energy is absorbed by the upper layers of soil. As a result, the contribution of each layer to radiation visible for radiometer decreases with depth. The thickness of the surface layer, which significantly contributes to the energy measured by the radiometer is defined as the "penetration depth". In order to improve the physical base of the methodology of soil moisture measurements using microwave remote sensing and to determine the effective emission depth seen by the radiometer, a new algorithm was developed. This algorithm determines the reflectance coefficient from Fresnel equations, and, what is new, the complex dielectric constant of the soil, calculated from the Usowicz's statistical-physical model (S-PM) of dielectric permittivity and conductivity of soil. The model is expressed in terms of electrical resistance and capacity. The unit volume of soil in the model consists of solid, water and air, and is treated as a system made up of spheres, filling volume by overlapping layers. It was assumed that connections between layers and spheres in the layer are represented by serial and parallel connections of "resistors" and "capacitors". The emissivity of the soil surface is calculated from the ratio between the brightness temperature measured by the ELBARA radiometer (GAMMA Remote Sensing AG) and the physical temperature of the soil surface measured by infrared sensor. As the input data for S-PM: volumes of soil components, mineralogical composition, organic matter content, specific surface area and bulk density of the soil were used. Water contents in the model are iteratively changed, until emissivities calculated from the S-PM reach the best agreement with emissivities measured by the radiometer. Final water content will correspond to the soil moisture measured by the radiometer. Then, the examined soil profile will be virtually divided into thin slices where moisture, temperature and thermal properties will be measured and simultaneously modelled via S-PM. In the next step, the slices will be "added" starting from top (soil surface), until the effective soil moisture will be equal to the soil moisture measured by ELBARA. The thickness of obtained stack will be equal to desired "penetration depth". Moreover, it will be verified further by measuring the moisture content using thermal inertia. The work was partially funded by the Government of Poland through an ESA Contract under the PECS ELBARA_PD project No. 4000107897/13/NL/KML.
Emission Studies Involving the Formation of (CX) and (DX) Band Systems of HgX (X=Cl,Br,I) Radicals
P. Misra; A. Michael; V. Kushawaha
Emission bands of the (C-X) and (D-X) systems of HgX (X=Cl,Br,I) radicals and atomic mercury lines during transitions from various excited levels to lower levels have been observed due to collisions of N and N2 ions and HgX2 molecules. Emission cross-sections have been determined at different laboratory kinetic energies of the projectile ions by using the integrated intensity of emission,
Broad-Line and Multi-Wave Band Emission from Blazars
NASA Astrophysics Data System (ADS)
Yi, Tingfeng; Xie, Guangzhong
We studied the correlations of the flux of the broad-line emission FBLR) with the X-ray emission flux, optical emission flux at 5500┼ and radio emission flux at 5GHz, respectively, for a large sample of 50 blazars [39 flat-spectrum radio quasars (FSRQs) and 11 BLLac objects]. Our main results are as follows. There are very strong correlations between FBLR and FX and between LBLR and LX in both states for 39 FSRQs, and the slopes of the linear-regression equations are almost equal to 1. There are weak correlations between FBLR and FX and between LBLR and LX for 11 BLLac objects in both states, and the slopes of the linear-regression equations are close to 1. There are significant correlations between FBLR and FX and between LBLR and LX for 50 blazars in both states, the slopes of both linear-regression equations are also close to 1. These results support a close link between relativistic jets and accretion onto the central Kerr black hole. On the other hand, we find that BLLac objects have a low accretion efficiency, ?, whereas FSRQs have a high ?. The unified model of FSRQs and BLLac objects is also discussed.
Dayglow and auroral emissions of Uranus in H2 FUV bands
NASA Astrophysics Data System (ADS)
Barthķlemy, M.; Lamy, L.; Menager, H.; Schulik, M.; Bernard, D.; Abgrall, H.; Roueff, E.; Cessateur, G.; Prange, R.; Lilensten, J.
Following the recent detection of an auroral signal on Uranus (Lamy et al. [2012]. Geophys. Res. Lett. 39, 7105) during HST/STIS observation performed in November 2011, we analyzed the associated HST/STIS FUV spectral images obtained in 2011 and 2012. Our purpose was to extract any possible H2 emission produced in the upper atmosphere of the planet. To interpret these data, we adapted a version of the kinetic Trans* code to the Uranian case. This code simulates the H2 emissions created by energetic particle precipitations in the upper atmosphere. The signal measured in the 1330-1700 ┼ range, of around 1.8 kR, is composed mostly of reflected sunlight with a small contribution from upper atmospheric emissions. For most spectra, we found no evidence of particle precipitation, indicating a precipitation flux smaller than 0.01 erg cm-2 s-1. For the spectrum of 29 November 2011 however, when an auroral spot was positively detected, we additionally identified a small contribution of H2 emission which requires a precipitating energy flux up to 0.05 erg cm-2 s-1. This study also establishes that the Hubble Space Telescope (HST) can be used to monitor the aurorae on Uranus in its image and spectral modes, and to estimate the associated precipitated energy flux, provided a very careful data processing is applied.
Relative spectral response corrected calibration inter-comparison of S-NPP VIIRS and Aqua MODIS thermal emissive bands
NASA Astrophysics Data System (ADS)
Efremova, Boryana; Wu, Aisheng; Xiong, Xiaoxiong
The S-NPP Visible Infrared Imaging Radiometer Suite (VIIRS) instrument is built with strong heritage from EOS MODIS, and has very similar thermal emissive bands (TEB) calibration algorithm and on-board calibrating source - a V-grooved blackbody. The calibration of the two instruments can be assessed by comparing the brightness temperatures retrieved from VIIRS and Aqua MODIS simultaneous nadir observations (SNO) from their spectrally matched TEB. However, even though the VIIRS and MODIS bands are similar there are still relative spectral response (RSR) differences and thus some differences in the retrieved brightness temperatures are expected. The differences depend on both the type and the temperature of the observed scene, and contribute to the bias and the scatter of the comparison. In this paper we use S-NPP Cross-track Infrared Sounder (CrIS) data taken simultaneously with the VIIRS data to derive a correction for the slightly different spectral coverage of VIIRS and MODIS TEB bands. An attempt to correct for RSR differences is also made using MODTRAN models, computed with physical parameters appropriate for each scene, and compared to the value derived from actual CrIS spectra. After applying the CrIS-based correction for RSR differences we see an excellent agreement between the VIIRS and Aqua MODIS measurements in the studied band pairs M13-B23, M15-B31, and M16- B32. The agreement is better than the VIIRS uncertainty at cold scenes, and improves with increasing scene temperature up to about 290K.
Follette, Katherine B.; Close, Laird [Steward Observatory, The University of Arizona, 933 N Cherry Ave, Tucson, AZ 85721 (United States)] [Steward Observatory, The University of Arizona, 933 N Cherry Ave, Tucson, AZ 85721 (United States); Tamura, Motohide; Hashimoto, Jun; Kwon, Jungmi; Kandori, Ryo [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)] [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Whitney, Barbara [Astronomy Department, University of Wisconsin-Madison, 475 N. Charter Street, Madison, WI 53706 (United States)] [Astronomy Department, University of Wisconsin-Madison, 475 N. Charter Street, Madison, WI 53706 (United States); Grady, Carol [Eureka Scientific, 2452 Delmer, Suite 100, Oakland, CA 96002 (United States)] [Eureka Scientific, 2452 Delmer, Suite 100, Oakland, CA 96002 (United States); Andrews, Sean M. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)] [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Wisniewski, John [H.L. Dodge Department of Physics and Astronomy, University of Oklahoma, 440 W Brooks St Norman, OK 73019 (United States)] [H.L. Dodge Department of Physics and Astronomy, University of Oklahoma, 440 W Brooks St Norman, OK 73019 (United States); Brandt, Timothy D.; Dong, Ruobing [Department of Astrophysical Sciences, Princeton University, NJ 08544 (United States)] [Department of Astrophysical Sciences, Princeton University, NJ 08544 (United States); Mayama, Satoshi [The Center for the Promotion of Integrated Sciences, The Graduate University for Advanced Studies (Sokendai), Shonan International Village, Hayama-cho, Miura-gun, Kanagawa 240-0193 (Japan)] [The Center for the Promotion of Integrated Sciences, The Graduate University for Advanced Studies (Sokendai), Shonan International Village, Hayama-cho, Miura-gun, Kanagawa 240-0193 (Japan); Abe, Lyu [Laboratoire Lagrange, UMR7293, Universite de Nice-Sophia Antipolis, CNRS, Observatoire de la Cote d'Azur, F-06300 Nice (France)] [Laboratoire Lagrange, UMR7293, Universite de Nice-Sophia Antipolis, CNRS, Observatoire de la Cote d'Azur, F-06300 Nice (France); Brandner, Wolfgang; Feldt, Markus [Max Planck Institute for Astronomy, Koenigstuhl 17, D-69117 Heidelberg (Germany)] [Max Planck Institute for Astronomy, Koenigstuhl 17, D-69117 Heidelberg (Germany); Carson, Joseph [Department of Physics and Astronomy, College of Charleston, 58 Coming St., Charleston, SC 29424 (United States)] [Department of Physics and Astronomy, College of Charleston, 58 Coming St., Charleston, SC 29424 (United States); Currie, Thayne [Department of Astronomy and Astrophysics, University of Toronto, 50 St. George Street M5S 3H4, Toronto Ontario (Canada)] [Department of Astronomy and Astrophysics, University of Toronto, 50 St. George Street M5S 3H4, Toronto Ontario (Canada); Egner, Sebastian E. [Subaru Telescope, 650 North Aohoku Place, Hilo, HI 96720 (United States)] [Subaru Telescope, 650 North Aohoku Place, Hilo, HI 96720 (United States); Goto, Miwa, E-mail: firstname.lastname@example.com [Universitats-Sternwarte Munchen, Ludwig-Maximilians-Universitat, Scheinerstr. 1, D-81679 Munchen (Germany)] [Universitats-Sternwarte Munchen, Ludwig-Maximilians-Universitat, Scheinerstr. 1, D-81679 Munchen (Germany); and others
We present the first near infrared (NIR) spatially resolved images of the circumstellar transitional disk around SR21. These images were obtained with the Subaru HiCIAO camera, adaptive optics, and the polarized differential imaging technique. We resolve the disk in scattered light at H-band for stellocentric 0.''1 {<=} r {<=} 0.''6 (12 {approx}< r {approx}< 75 AU). We compare our results with previously published spatially resolved 880 {mu}m continuum Submillimeter Array images that show an inner r {approx}< 36 AU cavity in SR21. Radiative transfer models reveal that the large disk depletion factor invoked to explain SR21's sub-mm cavity cannot be 'universal' for all grain sizes. Even significantly more moderate depletions ({delta} = 0.1, 0.01 relative to an undepleted disk) than those that reproduce the sub-mm cavity ({delta} {approx} 10{sup -6}) are inconsistent with our H-band images when they are assumed to carry over to small grains, suggesting that surface grains scattering in the NIR either survive or are generated by whatever mechanism is clearing the disk midplane. In fact, the radial polarized intensity profile of our H-band observations is smooth and steeply inwardly-increasing (r {sup -3}), with no evidence of a break at the 36 AU sub-mm cavity wall. We hypothesize that this profile is dominated by an optically thin disk envelope or atmosphere component. We also discuss the compatibility of our data with the previously postulated existence of a sub-stellar companion to SR21 at r {approx} 10-20 AU, and find that we can neither exclude nor verify this scenario. This study demonstrates the power of multiwavelength imaging of transitional disks to inform modeling efforts, including the debate over precisely what physical mechanism is responsible for clearing these disks of their large midplane grains.
Mapping H-band Scattered Light Emission in the Mysterious SR21Transitional Disk
NASA Technical Reports Server (NTRS)
Follette, Katherine B.; Motohide, Tamura; Hashimoto, Jun; Whitney, Barbara; Grady, Carol; Close, Laird; Andrews, Sean M.; Kwon, Jungmi; Wisniewski, John; Brandt, Timothy D.; Mayama, Satoshi; Kandori, Ryo; Dong, Ruobing; Abe, Lyu; Brandner, Wolfgang; Carson, Joseph; Currie, Thayne; Egner, Sebastian E.; Feldt, Markus; Goto, Miwa; Guyon, Olivier.; Hayano, Yutaka; McElwain, Michael W.; Hayashi, Masahiko; Hayashi, Saeko
We present the first near infrared (NIR) spatially resolved images of the circumstellar transitional disk around SR21. These images were obtained with the Subaru HiCIAO camera, adaptive optics, and the polarized differential imaging technique. We resolve the disk in scattered light at H-band for stellocentric 0.1 < or approx. r < or approx. 0.6 (12 < or approx. r < or approx. 75AU). We compare our results with previously published spatially resolved 880 micron continuum Submillimeter Array images that show an inner r < or approx. 36AU cavity in SR21. Radiative transfer models reveal that the large disk depletion factor invoked to explain SR21's sub-mm cavity cannot be "universal" for all grain sizes. Even significantly more moderate depletions (delta = 0.1, 0.01 relative to an undepleted disk) than those that reproduce the sub-mm cavity (delta approx. 10(exp -6) are inconsistent with our H-band images when they are assumed to carry over to small grains, suggesting that surface grains scattering in the NIR either survive or are generated by whatever mechanism is clearing the disk midplane. In fact, the radial polarized intensity profile of our H-band observations is smooth and steeply inwardly-increasing (r(sup -3), with no evidence of a break at the 36AU sub-mm cavity wall. We hypothesize that this profile is dominated by an optically thin disk envelope or atmosphere component.We also discuss the compatibility of our data with the previously postulated existence of a sub-stellar companion to SR21 at r approx. 10-20AU, and find that we can neither exclude nor verify this scenario. This study demonstrates the power of multiwavelength imaging of transitional disks to inform modeling efforts, including the debate over precisely what physical mechanism is responsible for clearing these disks of their large midplane grains.
Extreme Emission Line Galaxies in CANDELS: Broad-Band Selected, Star-Bursting Dwarf Galaxies at Z greater than 1
NASA Technical Reports Server (NTRS)
vanderWel, A.; Straughn, A. N.; Rix, H.-W.; Finkelstein, S. L.; Koekemoer, A. M.; Weiner, B. J.; Wuyts, S.; Bell, E. F.; Faber, S. M.; Trump, J. R.; Koo, D. C.; Ferguson, H. C.; Scarlata, C.; Hathi, N. P.; Dunlop, J. S.; Newman, J. A.; Dickinson, M.; Jahnke, K.; Salmon, B. W.; deMello, D. F.; Kkocevski, D. D.; Lai, K.; Grogin, N. A.; Rodney, S. A.; Guo, Yicheng
We identify an abundant population of extreme emission line galaxies (EELGs) at redshift z approx. 1.7 in the Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey (CANDELS) imaging from Hubble Space Telescope/Wide Field Camera 3 (HST/WFC3). 69 EELG candidates are selected by the large contribution of exceptionally bright emission lines to their near-infrared broad-band magnitudes. Supported by spectroscopic confirmation of strong [OIII] emission lines . with rest-frame equivalent widths approx. 1000A in the four candidates that have HST/WFC3 grism observations, we conclude that these objects are galaxies with approx.10(exp 8) Solar Mass in stellar mass, undergoing an enormous starburst phase with M*/M* of only approx. 15 Myr. These bursts may cause outflows that are strong enough to produce cored dark matter profiles in low-mass galaxies. The individual star formation rates and the co-moving number density (3.7x10(exp -4) Mpc(sup -3) can produce in approx.4 Gyr much of the stellar mass density that is presently contained in 10(exp 8) - 10(exp 9) Solar Mass dwarf galaxies. Therefore, our observations provide a strong indication that many or even most of the stars in present-day dwarf galaxies formed in strong, short-lived bursts, mostly at z > 1.
Extreme Emission Line Galaxies in CANDELS: Broad-Band Selected, Star-Bursting Dwarf Galaxies at Z greater than 1
NASA Technical Reports Server (NTRS)
VanDerWel, A.; Straughn, A. N.; Rix, H.-W.; Finkelstein, S. L.; Koekemoer, A. M.; Weiner, B. J.; Wuyts, S.; Bell, E. F.; Faber, S. M.; Trump, J. R.; Koo, D.; Ferguson, H. C.; Scarlata, C.; Hathi, N. P.; Dunlop, J. S.; Newman, J. A.; Kocevski, D. D.; Lai, K.; Grogin, N. A.; Rodney, S. A.; Lee, K.-S.; Guo, Y.
We identify an abundant population of extreme emission line galaxies at redshift z=1.6 - 1.8 in the Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey (CANDELS) imaging from Hubble Space Telescope/Wide Field Camera 3 (HST/WFC3). 69 candidates are selected by the large contribution of exceptionally bright emission lines to their near-infrared, broad-band fluxes. Supported by spectroscopic confirmation of strong [OIII] emission lines - with equivalent widths approximately 1000A - in the four candidates that have HST/WFC3 grism observations, we conclude that these objects are dwarf galaxies with approximately 10(exp 8) solar mass in stellar mass, undergoing an enormous star-burst phase with M*/M* of only approximately 10 Myr. The star formation activity and the co-moving number density (3.7 x 10(exp -4) Mpc(exp -3)) imply that strong, short-lived bursts play a significant, perhaps even dominant role in the formation and evolution of dwarf galaxies at z greater than 1. The observed star formation activity can produce in less than 5 Gyr the same amount of stellar mass density as is presently contained in dwarf galaxies. Therefore, our observations provide a strong indication that the stellar populations of present-day dwarf galaxies formed mainly in strong, short-lived bursts, mostly at z greater than 1.
Blue Luminescence and Extended Red Emission: Possible Connections to the Diffuse Interstellar Bands
NASA Astrophysics Data System (ADS)
Witt, A. N.
Blue luminescence (BL) and extended red emission (ERE) are observed as diffuse, optical-wavelength emissions in interstellar space, resulting from photoluminescence by ultraviolet(UV)-illuminated interstellar grains. Faintness and the challenge of separating the BL and ERE from the frequently much brighter dust-scattered continuum present major observational hurdles, which have permitted only slow progress in testing the numerous models that have been advanced to explain these two phenomena. Both the ERE, peaking near 680 nm (FWHM ~ 60 - 120 nm) and the BL, asymmetrically peaking at ~ 378 nm (FWHM ~ 45 nm), were first discovered in the Red Rectangle nebula. Subsequently, ERE and BL have been observed in other reflection nebulae, and in the case of the ERE, in carbon-rich planetary nebulae, H II regions, high-latitude cirrus clouds, the galactic diffuse ISM, and in external galaxies. BL exhibits a close spatial and intensity correlation with emission in the aromatic emission feature at 3.3 micron, most likely arising from small, neutral polycyclic aromatic hydrocarbon (PAH) molecules. The spectral characteristics of the BL also agree with those of fluorescence by PAH molecules with 13 to 19 carbon atoms. The BL phenomenon is thus most readily understood as the optical fluorescence of small, UV-excited aromatic molecules. The ERE, by contrast, though co-existent with mid-IR PAH emissions, does not correlate with emissions from either neutral or ionized PAHs. Instead, the spatial ERE morphology appears to be strictly governed by the density of far-UV (E >= 10.5 eV) photons, which are required for the ERE excitation. The most restrictive observational constraint for the ERE process is its exceptionally high quantum efficiency. If the ERE results from photo-excitation of a nano-particle carrier by photons with E >= 10.5 eV in a single-step process, the quantum efficiency exceeds 100%. Such a process, in which one to three low-energy optical photons may be emitted following a single far-UV excitation, is possible in highly isolated small clusters, e.g. small, dehydrogenated carbon clusters with about 20 to 28 carbon atoms. A possible connection between the ERE carriers and the carriers of DIBs may exist in that both are ubiquitous throughout the diffuse interstellar medium and both have an abundance of low-lying electronic levels with E <= 2.3 eV above the ground state.
Stimulated emission within the exciplex band by plasmonic-nanostructured polymeric heterojunctions
NASA Astrophysics Data System (ADS)
Zhang, Xinping; Li, Hongwei; Wang, Yimeng; Liu, Feifei
Organic heterojunctions have been extensively employed in the design of light-emitting diodes, photovoltaic devices, and thin-film field-effect transistors, which can be achieved by constructing a bilayer or a multi-layered thin-film deposition, or by blending two or more organic semiconductors with different charge-transport performances. Charge transfer excited states or exciplex may form on the heterointerfaces. Efficient light-emitting diodes have been demonstrated using exciplex emission. However, lasing or stimulated emission processes have not been observed with exciplex formation at organic heterojunctions. In this work, we demonstrate strong coherent interaction between photons and exciplex formation in the blends of poly-9,9'-dioctylfluorene-co-bis-N,N'-(4-butylphenyl)-bis-N,N'-phenyl-l,4-phenylenediamine (PFB) and poly-9,9'-dioctylfluorene-co-benzothiadiazole (F8BT), leading to transient stimulated exciplex emission. The responsible mechanisms involve plasmonic local-field enhancement and plasmonic feedback in a three-dimensional gold-nanoparticle matrix.Organic heterojunctions have been extensively employed in the design of light-emitting diodes, photovoltaic devices, and thin-film field-effect transistors, which can be achieved by constructing a bilayer or a multi-layered thin-film deposition, or by blending two or more organic semiconductors with different charge-transport performances. Charge transfer excited states or exciplex may form on the heterointerfaces. Efficient light-emitting diodes have been demonstrated using exciplex emission. However, lasing or stimulated emission processes have not been observed with exciplex formation at organic heterojunctions. In this work, we demonstrate strong coherent interaction between photons and exciplex formation in the blends of poly-9,9'-dioctylfluorene-co-bis-N,N'-(4-butylphenyl)-bis-N,N'-phenyl-l,4-phenylenediamine (PFB) and poly-9,9'-dioctylfluorene-co-benzothiadiazole (F8BT), leading to transient stimulated exciplex emission. The responsible mechanisms involve plasmonic local-field enhancement and plasmonic feedback in a three-dimensional gold-nanoparticle matrix. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr00140d
The electrosphere of macroscopc ""nuclei"": diffuse emissions in the MeV band from dark antimatter
Forbes, Michael Mcneil [Los Alamos National Laboratory; Lawson, Kyle [CANADA; Zhitnitsky, Ariel R [CANADA
Using a Thomas-Fermi model, we calculate the structure of the electrosphere of the quark antimatter nuggets postulated to comprise much of the dark matter. This provides a single self-consistent density profile from ultra-rel ativistic densities to the non-relativistic Boltzmann regime. We use this to present a microscopically justified calculation of several properties of the nuggets, including their net charge, and the ratio of MeV to 511 keV emissions from electron annihilation. We find that the calculated parameters agree with previous phenomenological estimates based on the observational supposition that the nuggets are a source of several unexplained diffuse emissions from the galaxy. This provides another nontrivial verification of the dark matter proposal. The structure of the electrosphere is quite general and will also be valid at the surface of strange-quark stars, should they exist.
Stimulated emission within the exciplex band by plasmonic-nanostructured polymeric heterojunctions.
Zhang, Xinping; Li, Hongwei; Wang, Yimeng; Liu, Feifei
Organic heterojunctions have been extensively employed in the design of light-emitting diodes, photovoltaic devices, and thin-film field-effect transistors, which can be achieved by constructing a bilayer or a multi-layered thin-film deposition, or by blending two or more organic semiconductors with different charge-transport performances. Charge transfer excited states or exciplex may form on the heterointerfaces. Efficient light-emitting diodes have been demonstrated using exciplex emission. However, lasing or stimulated emission processes have not been observed with exciplex formation at organic heterojunctions. In this work, we demonstrate strong coherent interaction between photons and exciplex formation in the blends of poly-9,9'-dioctylfluorene-co-bis-N,N'-(4-butylphenyl)-bis-N,N'-phenyl-l,4-phenylenediamine (PFB) and poly-9,9'-dioctylfluorene-co-benzothiadiazole (F8BT), leading to transient stimulated exciplex emission. The responsible mechanisms involve plasmonic local-field enhancement and plasmonic feedback in a three-dimensional gold-nanoparticle matrix. PMID:25757393
Remote Sensing of lower thermospheric temperature and composition based on observations of O2 Atmospheric band emission.
NASA Astrophysics Data System (ADS)
Christensen, A. B.; Yee, J.; Budzien, S. A.; Bishop, R. L.; Hecht, J. H.; Stephan, A. W.; Crowley, G.
The properties of the O2 Atmospheric bands emitted in the lower thermosphere are examined through the use of a photochemical model and compared with measurements from the RAIDS near-infrared spectrometer on the International Space Station. An updated model (Yee, 2011) has been used to establish the sensitivity of the line-of-sight (LOS) brightness of the (0,0), (1,1) and (0,1) bands to changes in neutral composition and some reaction rate and branching ratios. We found that the most sensitive region to O2 variability is near 120 km where the brightness is ~ [O2]^2. Calculations based on the MSIS-90E neutral atmospheric model corresponding to the geographical locations of the brightness measurements at 120 and 125 km for several days of observations indicate greater variability in the model results than observed by RAIDS based on our current understanding of the pointing errors. Up to about 200 km the (0,0) band lifetime is sufficiently long to allow thermalization of the upper state through collisions with the background gasses making the rotational distribution representative of the local temperature. The analysis of rocket data by Heller et al. (1991) and more recently Sheese et al. (2010) using OSIRIS observations up to an altitude of ~ 110 km illustrates the approach. Using the same measurement concept, the RAIDS data extend the range of altitudes an additional two scale heights to approximately 130 km. Comparing RAIDS and TIMED/SABER LOS measurements we have been able to validate temperatures in the region around 100 km. During moderate geomagnetic activity (Kp ~ 4) localized but greatly enhanced temperatures have been observed. J. W. Heller, A. B. Christensen, J. H. Yee and W. E. Sharp, Mesospheric temperature inferred from daytime observation of the O2 atmospheric (0,0) band system, J. Geophys. Res., 96,19,499-19,505,1991. P. E. Sheese, E. J. Llewellyn, R. L. Gattinger, A. E. Bourassa, D. A. Degenstein, N. D. Lloyd, and I. C. McDade, Temperatures in the upper mesosphere and lower thermosphere from OSIRIS observations of O2 A-band emission spectra, Can. J. Phys. 88, 919-925, 2010. J. H. Yee, (private communication, 2011)
Spontaneous emission from a two-level atom in anisotropic one-band photonic crystals: A fractional calculus approach
Wu, J.-N.; Huang, C.-H. [Department of Photonics and Institute of Electro-Optical Engineering, National Chiao Tung University, Hsinchu, Taiwan (China); Cheng, S.-C. [Department of Physics, Chinese Culture University, Taipei, Taiwan (China); Hsieh, W.-F. [Department of Photonics and Institute of Electro-Optical Engineering, National Chiao Tung University, Hsinchu, Taiwan (China); Institute of Electro-Optical Science and Engineering, National Cheng Kung University, Tainan, Taiwan (China)
Spontaneous emission (SE) from a two-level atom in an anisotropic photonic crystal (PC) is investigated by the fractional calculus. Physical phenomena of the SE are studied analytically by solving the fractional kinetic equations of the SE. There is a dynamical discrepancy between the SE of anisotropic and isotropic PCs. We find that, contrary to the SE phenomenon of the isotropic PC, the SE near the band edge of an anisotropic PC shows no photon-atom bound state. It is consistent with the experimental results of Barth, Schuster, Gruber, and Cichos [Phys. Rev. Lett. 96, 243902 (2006)] that the anisotropic property of the system enhances the SE. We also study effects of dispersion curvatures on the changes of the photonic density of states and the appearance of the diffusion fields in the SE.
The effects of soil moisture, surface roughness, and vegetation on L-band emission and backscatter
NASA Technical Reports Server (NTRS)
Wang, James R.; Shiue, J. C.; Engman, Edwin T.; Schmugge, Thomas J.; Mo, Tsan
Measurements performed with SIR-B at 1.28 GHz and an airborne multiple-beam push-broom radiometer at 1.4 GHz over agricultural fields near Fresno, California are examined. A theoretical model (Kirchhoff approximation) was used to assess the effects of surface roughness and vegetation (alfalfa and lettuce) with respect to the responses of microwave emission and backscatter to soil-moisture variations. It is found that the surface roughness plays a dominant role compared to the vegetation cover in the microwave backscatter.
Spatial variation of the 3.29 and 3.40 micron emission bands within reflection nebulae and the photochemical evolution of methylated polycyclic aromatic hydrocarbons.
Joblin, C; Tielens, A G; Allamandola, L J; Geballe, T R
Spectra of 3 micrometers emission features have been obtained at several positions within the reflection nebulae NGC 1333 SVS3 and NGC 2023. Strong variations of the relative intensities of the 3.29 micrometers feature and its most prominent satellite band at 3.40 micrometers are found. It is shown that (i) the 3.40 micrometers band is too intense with respect to the 3.29 micrometers band at certain positions to arise from hot band emission alone, (ii) the 3.40 micrometers band can be reasonably well matched by new laboratory spectra of gas-phase polycyclic aromatic hydrocarbons (PAHs) with alkyl (-CH3) side groups, and (iii) the variations in the 3.40 micrometers to 3.29 micrometers band intensity ratios are consistent with the photochemical erosion of alkylated PAHs. We conclude that the 3.40 micrometers emission feature is attributable to -CH3 side groups on PAH molecules. We predict a value of 0.5 for the peak intensity ratio of the 3.40 and 3.29 micrometers emission bands from free PAHs in the diffuse interstellar medium, which would correspond to a proportion of one methyl group for four peripheral hydrogens. We also compare the 3 micrometers spectrum of the proto-planetary nebula IRAS 05341+0852 with the spectrum of the planetary nebula IRAS 21282+5050. We suggest that a photochemical evolution of the initial aliphatic and aromatic hydrocarbon mixture formed in the outflow is responsible for the changes observed in the 3 micrometers emission spectra of these objects. PMID:11538557
The modeling of emissions of Lyman-Birge-Hopfield and Vegard-Kaplan bands in the atmospheres of planets
NASA Astrophysics Data System (ADS)
Kirillov, Andrey S.
Molecular nitrogen is main component in the atmospheres of Earth, Titan, Triton. Energetic particles interacting with the atmospheres cause electronic excitation of nitrogen molecules. Total quenching rate coefficients of three singlet and four triplet states of molecular nitrogen in the collisions with N2 and O2 molecules are calculated on the basis of quantum-chemical approximations. The calculated rate coefficients of electronic quenching of N2* molecules are compared with available experimental data. An influence of radiational and collisional processes on vibrational populations of electronically excited N2(a1) and N2(A3) molecules and emissions of Lyman-Birge-Hopfield and Vegard-Kaplan bands is studied for the mixture of N2 and O2 at different pressures. It is indicated that molecular collisions cause changes in relative populations of vibrational levels of the states and intensity relations of ultraviolet bands of N2 with the rise in the pressure and O2 admixture. The influence of electronically excited molecules on vibrational kinetics of molecular nitrogen is discussed.
Day-side z'-band Emission and Eccentricity of WASP-12b
NASA Astrophysics Data System (ADS)
L¾pez-Morales, Mercedes; Coughlin, Jeffrey L.; Sing, David K.; Burrows, Adam; Apai, Dßniel; Rogers, Justin C.; Spiegel, David S.; Adams, Elisabeth R.
We report the detection of the eclipse of the very hot Jupiter WASP-12b via z'-band time-series photometry obtained with the 3.5 m Astrophysical Research Consortium telescope at Apache Point Observatory. We measure a decrease in flux of 0.082% ▒ 0.015% during the passage of the planet behind the star. That planetary flux is equally well reproduced by atmospheric models with and without extra absorbers, and blackbody models with f >= 0.585 ▒ 0.080. It is therefore necessary to measure the planet at other wavelengths to further constrain its atmospheric properties. The eclipse appears centered at phase phi = 0.5100+0.0072 -0.0061, consistent with an orbital eccentricity of |ecos ?| = 0.016+0.011 -0.009 (see note at the end of Section 4). If the orbit of the planet is indeed eccentric, the large radius of WASP-12b can be explained by tidal heating. Based on observations collected with the Apache Point Observatory 3.5 m telescope, which is owned and operated by the Astrophysical Research Consortium (ARC).
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Effect of annealing on lattice strain and near-band-edge emission of ZnO nanorods
NASA Astrophysics Data System (ADS)
Babikier, Musbah; Wang, Jinzhong; Wang, Dunbo; Li, Qian; Sun, Jianming; Yan, Yuan; Wang, Wenqi; Yu, Qingjiang; Jiao, Shujie; Gao, Shiyong; Li, Hongtao
The effect of air and oxygen annealing on the structural and the optical properties of hydrothermally synthesized ZnO nanorods was investigated. After hydrothermal synthesis, the resulting ZnO nanorods were annealed in air and under an oxygen atmosphere at 370░C for 1 h. X-ray diffraction results revealed that the oxygen-annealed nanorods possessed high crystallinity with a hexagonal-wurtzite crystal structure in the (002) plane. Evaluation of strain showed a tensile lattice strain of 0.426% resulting from oxygen annealing. The photoluminescence measurements showed that the relative intensity ratio of the near-band-edge emission (NBE) to the green emission ( I NBE / I GE ) increased from ~2.6 for the as-grown ZnO nanorods to ~68.7 when the nanorods were annealed under oxygen. After annealing, a red shift of ~30 and ~44 meV in the NBE was observed for the nanorods that were annealed in air and under oxygen, respectively. This shift is attributed to the interaction between the neutral acceptors and the adsorbed oxygen atoms.
Thermospheric dark band structures observed in all-sky OI 630 nm emission images over the Brazilian low-latitude sector
A. A. Pimenta; M. C. Kelley; Y. Sahai; J. A. Bittencourt; P. R. Fagundes
Using two ground-based all-sky imaging systems, measurements of moving dark band structures in the OI 630.0 nm nightglow emission were detected in the low-latitude region of Brazil. On the nights of 30¢31 August 1995, 18¢19 July 1998, and 13¢14 July 1999, the all-sky imaging observations of the OI 630 nm emission, carried out at Cachoeira Paulista (22.7░S, 45░W, magnetic declination
A Balloon-borne Limb-Emission Sounder at 650-GHz band for Stratospheric observations
NASA Astrophysics Data System (ADS)
Irimajiri, Yoshihisa; Ochiai, Satoshi
We have developed a Balloon-borne Superconducting Submillimeter-Wave Limb-Emission Sounder (BSMILES) to observe stratospheric minor constituents like ozone, HCl etc. BSMILES carries a 300mm-diameter offset parabolic antenna, a 650-GHz heterodyne superconducting (SIS) low-noise receiver, and an acousto-optical spectrometer (AOS) with the bandwidth of 1GHz and the resolution of 1MHz. Gondola size is 1.35 m x 1.35 m x 1.26 m. Total weight is about 500 kg. Limb observations are made by scanning the antenna beam of about 0.12 degrees (FWHM) in vertical direction. A calibrated hot load (CHL) and elevation angle of 50 degrees are ob-served after each scan for calibration. The DSB system noise temperature of the SIS receiver is less than 460 K at 624-639 GHz with a best value of 330 K that is 11 times as large as the quantum limit. Data acquisition and antenna control are made by on-board PCs. Observed data are recorded to PC card with 2 GB capacity to collect after the observations from the sea, and HK data are transmitted to the ground. Gondola attitude is measured by three-axis fiber-optical gyroscope with accuracy less than 0.01 degrees, three-axis accelerometer, and a two-axis geoaspect sensor. Electric power is supplied by lithium batteries. Total power con-sumption is about 150W. Almost all systems are put in pressurized vessels for waterproofing, heat dissipation, and noise shield, etc. BSMILES was launched from Sanriku Balloon Center of Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), at the east coast of Japan, in the summer of 2003, 2004, and 2006. The gondola was carried to an altitude of 35 km by a balloon of 100,000 m3 in volume and the observations were made for 1.5 hours in 2004. All systems operated normally by keeping their temperature within the limit of operation by keeping gondola warm with styrene foam. After the observations, the gondola was dropped and splashed on the Pacific Ocean by a parachute and retrieved by using a boat. Almost all systems were waterproofed and it turns out that they are reusable. The emission line spectra of ozone, HCl, and HO2 etc. were observed. We would like to thank the member of balloon group of ISAS/JAXA for the successful balloon flight of BSMILES.
Interpretation of broad-band polarimetry of solar coronal transients - Importance of H-alpha emission
NASA Technical Reports Server (NTRS)
Poland, A. I.; Munro, R. H.
An eruptive prominence and coronal transient was observed in H-alpha, He II 304-A, and coronal white light (3700-7000 A). This event was generically similar to many other coronal transients associated with eruptive prominences in that loops of material propagated outward through the corona. It differed in that some of the prominence material was observed above 1.75 solar radii in both coronal white light and He II. Polarization analysis of the white-light data shows that the observed radiance from the loop-like transient was entirely due to free electron or Thomson scattering, whereas the white-light radiance from the prominence material was dominated by H-alpha emission. By comparing the white-light observations with model calculations, the densities along the loop and limits on the temperature and density of the prominence are obtained. Material observed in both white light and He II is shown to be cool prominence material, whereas analysis indicates that the transient-loop material is hot and coronal in origin. The time sequence of observations leads to the hypothesis that the prominence material is heated as it is ejected from the sun.
Determining Limits on the Intensity of the O2 0-0 Atmospheric Band Emission in the Venus Nightglow
NASA Astrophysics Data System (ADS)
Slanger, T. G.; Migliorini, A.; Gray, C.
Recombination of oxygen atoms is the source of excited O2 states in the nighttime mesospheres of the terrestrial planets - Venus, Earth, and Mars. Emission in the O2 Atmospheric 0-0 band at 762 nm is one of the strongest features in the terrestrial visible/near-IR spectral region, with a typical intensity of 5 kR, although this emission does not reach the ground due to self-absorption. We inquire as to what intensity is expected at Venus, although there are no published spectra for either Venus or Mars in this spectral region. A recent estimated upper limit of 200 R for Venus has been given [Krasnopolsky, 2011]. The calculation requires knowledge of the temperature-dependent rate coefficients for three-body oxygen atom recombination in CO2 and for O2(b, v = 0) removal by CO2, as well as an estimate for the fraction of stabilized excited O2 molecules that reach b(v = 0). The resultant nadir intensity depends on [O(3P)]2, and for a value of [O(3P)] = 1.5 ū 1011 cm-3, the 95-km intensity is of the order of 2 R, probably accurate to within a factor of two. Such a value is consistent with the lack of detection in recent Venus Express VIRTIS spectra, which include the 762 nm region. Measurements of the Venus nightglow with the 3.5-m telescope at Apache Point Observatory in December, 2010 also show no 762 nm emission, where in principle the 0.03 nm Doppler shift in the emission due to the relative velocities of Earth and Venus could have made observation possible. The principal differences between the Venus and Earth cases are (1) quenching of O2(b, v = 0) is more than two orders of magnitude faster by CO2 than by N2 (the terrestrial quencher) and (2) the densities in the ~95 km mesospheric nightglow region are two orders of magnitude higher at Venus. TGS acknowledge support for this work from the NASA Planetary Astronomy Program, Grant NNX08A0276. AM acknowledges ASI for support. Krasnopolsky, V.A., Planet. Space Sci. 59, 754-766, 2011.
Direct band gap optical emission from compressively strained Ge films grown on relaxed Si{sub 0.5}Ge{sub 0.5} substrate
Aluguri, R.; Manna, S.; Ray, S. K. [Department of Physics and Meteorology, Indian Institute of Technology Kharagpur, Kharagpur 721302 (India)] [Department of Physics and Meteorology, Indian Institute of Technology Kharagpur, Kharagpur 721302 (India)
Compressively strained Ge films have been grown on relaxed Si{sub 0.5}Ge{sub 0.5} virtual substrate in ultra high vacuum using molecular beam epitaxy. Structural characterization has shown that the Ge films are compressively strained with partial strain relaxation in a film thicker than 3.0 nm, due to onset of island nucleation. Photoluminescence spectra exhibit the splitting of degenerate Ge valence band into heavy hole and light hole bands with a broad direct band gap emission peak around 0.81 eV. Temperature and excitation power dependent emission characteristics have been studied to investigate the mechanism of luminescence quenching at high temperatures and the role of non-radiative recombination centers.
SDSS J083253.18+064316.7: one strange object with double-peaked narrow H? but single-peaked narrow H?
NASA Astrophysics Data System (ADS)
Zhang, Xue-Guang
In this Letter, we first report one unique object SDSS J0832+0643 with particular features of narrow Balmer emission lines: double-peaked narrow H? but single-peaked narrow H?. The particular features cannot be expected by currently proposed kinematic models for double-peaked narrow emission lines, because the proposed kinematic models lead to similar line profiles of narrow Balmer emission lines. However, due to radiative transfer effects, the non-kinematic model can be naturally applied to well explain the particular features of narrow Balmer emission lines: larger optical depth in H? than 10 leads to observed double-peaked narrow H?, but smaller optical depth in H? around 2 leads to observed single-peaked narrow H?. Therefore, SDSS J0832+0643 can be used as strong evidence to support the non-kinematic model for double-peaked narrow emission lines.
Improvements on Near Real Time Detection of Volcanic Ash Emissions for Emergency Monitoring with Limited Satellite Bands
NASA Astrophysics Data System (ADS)
Steensen, Torge; Webley, Peter; Dehn, Jon
Quantifying volcanic ash emissions syn-eruptively is an important task for the global aviation community. However, due to the near real time nature of volcano monitoring, many parameters important for accurate ash mass estimates cannot be obtained easily. Previous studies highlight the surface temperature, the refractive index of the ash and the cloud top temperature as most crucial of these values. Even when estimating those parameters best possible, uncertainties associated with the ash masses remain high, especially when the satellite data is only available in the traditional 10.8 and 12.0 Ąm bands. To counteract this limitation, we developed a quantitative comparison between the ash extents in satellite and model data. The main aspect is to manually define the cloud edge based on the available satellite data as well as other knowledge like pilot reports or ground-based observations. This manual aspect, although subjective to the experience of the observer, can show a significant improvement as it provides the ability to highlight ash that otherwise would be obscured by meteorological clouds or, by passing over different surfaces with unaccounted temperatures, might be lost entirely and thus remains undetectable for an automated satellite approach. We show comparisons to Volcanic Ash Transport and Dispersion models and outline a quantitative match as well as percentages of overestimates based on satellite or dispersion model data which can be converted into a level of reliability for near real time volcano monitoring.
The emission and scattering of L-band microwave radiation from rough ocean surfaces and wind speed measurements from the Aquarius sensor
NASA Astrophysics Data System (ADS)
Meissner, Thomas; Wentz, Frank J.; Ricciardulli, Lucrezia
In order to achieve the required accuracy in sea surface salinity (SSS) measurements from L-band radiometers such as the Aquarius/SAC-D or SMOS (Soil Moisture and Ocean Salinity) mission, it is crucial to accurately correct the radiation that is emitted from the ocean surface for roughness effects. We derive a geophysical model function (GMF) for the emission and backscatter of L-band microwave radiation from rough ocean surfaces. The analysis is based on radiometer brightness temperature and scatterometer backscatter observations both taken on board Aquarius. The data are temporally and spatially collocated with wind speeds from WindSat and F17 SSMIS (Special Sensor Microwave Imager Sounder) and wind directions from NCEP (National Center for Environmental Prediction) GDAS (Global Data Assimilation System). This GMF is the basis for retrieval of ocean surface wind speed combining L-band H-pol radiometer and HH-pol scatterometer observations. The accuracy of theses combined passive/active L-band wind speeds matches those of many other satellite microwave sensors. The L-band GMF together with the combined passive/active L-band wind speeds is utilized in the Aquarius SSS retrieval algorithm for the surface roughness correction. We demonstrate that using these L-band wind speeds instead of NCEP wind speeds leads to a significant improvement in the SSS accuracy. Further improvements in the roughness correction algorithm can be obtained by adding VV-pol scatterometer measurements and wave height (WH) data into the GMF.
Observation of an Intermediate Band in Sn-doped Chalcopyrites with Wide-spectrum Solar Response
Yang, Chongyin; Qin, Mingsheng; Wang, Yaoming; Wan, Dongyun; Huang, Fuqiang; Lin, Jianhua
Nanostrcutured particles and polycrystalline thin films of Sn-doped chalcopyrite are synthesized by newly-developed methods. Surprisingly, Sn doping introduces a narrow partially filled intermediate band (IB) located ~1.7?eV (CuGaS2) and ~0.8?eV (CuInS2) above the valance band maximum in the forbidden band gap. Diffuse reflection spectra and photoluminescence spectra reveal extra absorption and emission spectra induced by the IBs, which are further supported by first-principle calculations. Wide spectrum solar response greatly enhances photocatalysis, photovoltaics, and photo-induced hydrogen production due to the intermediate band. PMID:23412565
Quadratic Jahn-Teller Effect in the Line Shapes of the A-Emission and A-Absorption Bands in KBr: Tl+-Type Phosphors
NASA Astrophysics Data System (ADS)
Shiraishi, Toshiaki; Masunaga, Shoji
The adiabatic potential energy surfaces (APESÆs) of Tl+-type impurities in alkali halides, 3T1u(\\varGamma4-) and 3A1u(\\varGamma1-) have been calculated taking account of the spin-orbit interaction and both the linear and quadratic Jahn-Teller effect with the ?1g and \\varepsilong vibrational modes. It has been found that the 3T1u APESÆs have one kind of minima or the two kinds of minima, depending on whether we assume the linear or both the linear and quadratic Jahn-Teller interactions. A trap level 3A1u lies just below both the minima. The line shapes of the A-emission and A-absorption bands in KBr: Tl+ are calculated by using the Franck-Condon and Condon approximations. It has been found that the theoretical line shape of the A-emission band has the asymmetric doublet structure and reproduces the experimental emission bands AT and AX. This shows that the large energy differnce between the AX and AT bands is caused by the quadratic Jahn-Teller terms involving Q1(?1g).
Enhanced free exciton and direct band-edge emissions at room temperature in ultrathin ZnO films grown on Si nanopillars by atomic layer deposition.
Chang, Yuan-Ming; Shieh, Jiann; Chu, Pei-Yuan; Lee, Hsin-Yi; Lin, Chih-Ming; Juang, Jenh-Yih
Room-temperature ultraviolet (UV) luminescence was investigated for the atomic layer deposited ZnO films grown on silicon nanopillars (Si-NPs) fabricated by self-masking dry etching in hydrogen-containing plasma. For films deposited at 200 ░C, an intensive UV emission corresponding to free-exciton recombination (~3.31 eV) was observed with a nearly complete suppression of the defect-associated broad visible range emission peak. On the other hand, for ZnO films grown at 25 ░C, albeit the appearance of the defect-associated visible emission, the UV emission peak was observed to shift by ~60 meV to near the direct band edge (3.37 eV) recombination emission. The high-resolution transmission electron microscopy (HRTEM) showed that the ZnO films obtained at 25 ░C were consisting of ZnO nanocrystals with a mean radius of 2 nm embedded in a largely amorphous matrix. Because the Bohr radius of free-exictons in bulk ZnO is ~2.3 nm, the size confinement effect may have occurred and resulted in the observed direct band edge electron-hole recombination. Additionally, the results also demonstrate order of magnitude enhancement in emission efficiency for the ZnO/Si-NP structure, as compared to that of ZnO directly deposited on Si substrate under the same conditions. PMID:21967063
The Lowest of the Strongly Infrared Active Vibrations of the Fulleranes and Astronomical Emission Band at a Wavelength of 21-MICRONS
NASA Astrophysics Data System (ADS)
Webster, A.
The lowest of the strongly infrared-active vibrations of the fulleranes of the family C60Hm is investigated by calculating its wavelength on the basis of two models. In one the molecule is represented by an elastic shell and in the other it is represented by a standard force field. The wavelength is found to be a strong function of m, the number of hydrogen atoms, increasing monotonically from about 19 ?m for m = 0 to 23 ?m for m = 60, and the transition is usually split into a number of components spread over a wavelength range of order 1 ?m. It follows that the radiation in this transition from a mixed population of fulleranes is likely to consist of a broad band made up of many lines blended together, extending throughout much of the range from 19 to 23 ?m. A comparison is therefore made with the emission band centred near 21 ?m discovered by Kwok, Volk & Hrivnak in the shells around post-asymptotic giant branch stars, which has been measured to have similar properties. This band is only known in carbon-rich objects, many of which show the unidentified infrared features, in broad agreement with the idea that the features and the 21-?m band might both be carried by the fulleranes. It is suggested that in these objects both the 21-?m band and the unidentified infrared emission features may be collisionally excited.
Watanabe, Kyoko; Shimizu, Toshifumi [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan); Krucker, Saem; Hudson, Hugh [Space Sciences Laboratory, University of California at Berkeley, 7 Gauss Way, Berkeley, CA 94720-7450 (United States); Masuda, Satoshi [Solar-Terrestrial Environment Laboratory, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601 (Japan); Ichimoto, Kiyoshi, E-mail: firstname.lastname@example.com [Kwasan and Hida Observatories, Kyoto University, Yamashina, Kyoto 607-8471 (Japan)
We report on G-band emission observed by the Solar Optical Telescope on board the Hinode satellite in association with the X1.5-class flare on 2006 December 14. The G-band enhancements originate from the footpoints of flaring coronal magnetic loops, coinciding with nonthermal hard X-ray bremsstrahlung sources observed by the Reuven Ramaty High Energy Solar Spectroscopic Imager. At the available 2 minute cadence, the G-band and hard X-ray intensities are furthermore well correlated in time. Assuming that the G-band enhancements are continuum emission from a blackbody, we derived the total radiative losses of the white-light flare (white-light power). If the G-band enhancements additionally have a contribution from lines, the derived values are overestimates. We compare the white-light power with the power in hard X-ray producing electrons using the thick-target assumption. Independent of the cutoff energy of the accelerated electron spectrum, the white-light power and the power of accelerated electrons are roughly proportional. Using the observed upper limit of {approx}30 keV for the cutoff energy, the hard X-ray producing electrons provide at least a factor of 2 more power than needed to produce the white-light emission. For electrons above 40 keV, the powers roughly match for all four of the time intervals available during the impulsive phase. Hence, the flare-accelerated electrons contain enough energy to produce the white-light flare emissions. The observed correlation in time, space, and power strongly suggests that electron acceleration and white-light production in solar flares are closely related. However, the results also call attention to the inconsistency in apparent source heights of the hard X-ray (chromosphere) and white-light (upper photosphere) sources.
Resonant emission from the B870 exciton state and electron¢phonon coupling in the LH2 antenna chromoprotein
Margus Rõtsep; Arvi Freiberg
Fluorescence of the peripheral LH2 antenna complex from the photosynthetic bacterium Rhodobacter sphaeroides has been studied at 5 K upon selective excitation into the B870 exciton absorption band. Heterogeneous nature of the LH2 emission band has been confirmed by a double spectral selection technique simultaneously utilizing hole burning and fluorescence line narrowing spectroscopy. The phonon structure of the spectra related
Ballistic-electron-emission spectroscopy of Al{sub x}Ga{sub 1{minus}x}As/GaAs heterostructures: Conduction-band offsets, transport mechanisms, and band-structure effects
OShea, J.J.; Brazel, E.G.; Rubin, M.E.; Bhargava, S.; Chin, M.A.; Narayanamurti, V. [Materials Department, Physics Department, and Electrical and Computer Engineering Department, University of California, Santa Barbara, California 93106 (United States)
We report an extensive investigation of semiconductor band-structure effects in single-barrier Al{sub x}Ga{sub 1{minus}x}As/GaAs heterostructures using ballistic-electron-emission spectroscopy (BEES). The transport mechanisms in these single-barrier structures were studied systematically as a function of temperature and Al composition over the full compositional range (0{le}x{le}1). The initial ({Gamma}) BEES thresholds for Al{sub x}Ga{sub 1{minus}x}As single barriers with 0{le}x{le}0.42 were extracted using a model which includes the complete transmission probability of the metal-semiconductor interface and the semiconductor heterostructure. Band offsets measured by BEES are in good agreement with previous measurements by other techniques which demonstrates the accuracy of this technique. BEES measurements at 77 K give the same band-offset values as at room temperature. When a reverse bias is applied to the heterostructures, the BEES thresholds shift to lower voltages in good agreement with the expected bias-induced band-bending. In the indirect band-gap regime ({ital x}{gt}0.45), spectra show a weak ballistic-electron-emission microscopy current contribution due to intervalley scattering through Al{sub x}Ga{sub 1{minus}x}As {ital X} valley states. Low-temperature spectra show a marked reduction in this intervalley current component, indicating that intervalley phonon scattering at the GaAs/Al{sub x}Ga{sub 1{minus}x}As interface produces a significant fraction of this{ital X} valley current. A comparison of the BEES thresholds with the expected composition dependence of the Al{sub x}Ga{sub 1{minus}x}As {Gamma}, {ital L}, and {ital X} points yields good agreement over the entire composition range. {copyright} {ital 1997} {ital The American Physical Society}
Prediction of CO Cameron band and atomic oxygen visible emissions in comets C/2013 A1 (Siding Spring) and 67P/Churyumov-Gerasimenko
NASA Astrophysics Data System (ADS)
Raghuram, S.; Bhardwaj, A.
The forbidden emissions of cometary species have special importance in the cometary spectra. The excited species which produce these forbidden emissions can not be populated by direct solar radiation excitation. These metastable species are produced mainly from dissociative excitation and ion-electron recombination reactions. Thus the observed emissions have been used as tracers of parent cometary species. The CO (a3 -X1 ) is a forbidden transition which produces Cameron band emission in the ultraviolet region during dissociative excitation of CObearing neutrals and the dissociative recombination of CO-ionic species in the cometary coma. Similarly, the forbidden transitions of metastable atomic oxygen 1S-3P (green, 5577 ┼), and 1D-3P (red-doublet, 6300 and 6364 ┼) produce line emissions in the visible region. These emissions have been used to probe H2O and CO2 abundances in the comets. We have developed a coupled chemistry-emission model to study various production and loss mechanisms of these excited metastable states. The model is applied to comet C/2013 A1 (Siding Spring) which will have a close fly-by of Mars during mid October, 2014, when Indian Mars orbiter Mission and NASA's Maven, would be orbiting the planet. The model is also applied on ESA's Rosetta mission target comet 67P/Churyumov-Gerasimenko which will be useful for different observations over various heliocentric distances. The predicted intensities and quantitative analysis of these emissions can be a theoretical support for various space and ground-based observations.
Search for the OH (X2Pi) Meinel Band Emission in Meteors as a Tracer of Mineral Water in Comets: Detection of N2+ (AX)
Peter Jenniskens; Christophe O. Laux
We report the discovery of the N2+ A-X Meinel band in the 780-840 nm meteor emission from two Leonid meteoroids that were ejected less than 1,000 years ago by comet 55P\\/Tempel-Tuttle. Our analysis indicates that the N2+ molecule is at least an order of magnitude less abundant than expected, possibly as a result of charge transfer reactions with meteoric metal
Spectroscopy of Fe L-shell line emission from Fe XVII- XXIV in the 10--18 A wavelength band
NASA Astrophysics Data System (ADS)
Brown, Gregory Vallee
The line emission from the L-shell, n --> 2, transitions in Fe XVII-XXIV falling in the ultra-soft x-ray regime from 10-18 ┼ has been measured using the Electron Beam Ion Trap located at the Lawrence Livermore National Laboratory. The results of these measurements include wavelengths, relative intensities, and line identifications of over 150 features from Fe XVIII-XXIV. In addition, measurements of the intensity of the high- n L-shell transitions, i.e., n >= 5, in Fe XVII falling in the 9.8-11.5 ┼ wavelength band have been made. These measurements were done at single electron beam energies where the only population process is direct excitation followed by radiative cascades. Also presented in this work are the results of a systematic study of the relative and absolute cross sections of the 1s22s 22p1/22 p43/2 3d3/2J = 1 --> 1 s22s22p 6 J = 0 resonance to ls2 2s22 p21/2 2 p33/2 3d5/2J = 1 --> 1 s22s22p 6 J = 0 intercombination line in neon-like Fe XVII. This ratio was measured under conditions where different processes contribute to the line flux. The contributing processes are direct impact excitation followed by radiative cascades, blending with Fe XVI innershell satellites, and Fe XVI dielectronic recombination satellites involving capture into high- n levels. The measured ratio varies between 2.8 and 3.2 depending on the line formation processes. These values are higher than ratios measured in non-flaring active regions of the Sun. However, the measurements are significantly lower than values calculated with current atomic physics codes demonstrating that calculational methods are not yet accurate enough to provide relative intensities useful for comparative diagnostics. The results suggest that the relatively low ratio measured in non-flaring active regions may be a result of blending with innershell satellites of Fe XVI.
Optical spectroscopy of IRAS sources with infrared emission bands. II. IRAS 04324+5106, 06114+1745, 20319+3958, and 22539+5758
Cohen, M.; Jones, B.F.; Walker, H.J. (California Univ., Berkeley (USA); Lick Observatory, Santa Cruz, CA (USA); Search for Extraterrestrial Intelligence Institute, Los Altos, CA (USA))
The paper presents long-slit optical spectra and microwave CO spectra of four nebulous counterparts to IRAS sources showing PAH emission features: 04324+5106, 06114+1745, 20319+3958, and 22539+5758. IRAS 22539+5758 is associated with a bipolar nebula. All are allied with B-type stars that suffer appreciable circumstellar extinction, and whose environs show atomic emission lines; three represent mixed reflection/emission nebulosities. Three show spectroscopic evidence for outflows at about 100 km/s. One, 06114+1745, exhibits indications of enhanced diffuse interstellar bands. It is concluded that extinction alone is insufficient to yield enhanced DIBs and that peculiar circumstellar abundances and/or physical conditions must play a role. 20 refs.
Analysis and Modeling of Jovian Radio Emissions Observed by Galileo
NASA Technical Reports Server (NTRS)
Menietti, J. D.
Our studies of Jovian radio emission have resulted in the publication of five papers in refereed journals, with three additional papers in progress. The topics of these papers include the study of narrow-band kilometric radio emission; the apparent control of radio emission by Callisto; quasi-periodic radio emission; hectometric attenuation lanes and their relationship to Io volcanic activity; and modeling of HOM attenuation lanes using ray tracing. A further study of the control of radio emission by Jovian satellites is currently in progress. Abstracts of each of these papers are contained in the Appendix. A list of the publication titles are also included.
Integrated Advanced Microwave Sounding Unit-A (AMSU-A). Engineering Test Report: Radiated Emissions and SARR, SARP, DCS Receivers, Link Frequencies EMI Sensitive Band Test Results, AMSU-A1, S/N 108 2
NASA Technical Reports Server (NTRS)
Valdez, A.
This is the Engineering Test Report, Radiated Emissions and SARR, SARP, DCS Receivers, Link Frequencies EMI Sensitive Band Test Results, AMSU-A1 SIN 108, for the Integrated Advanced Microwave Sounding Unit-A (AMSU-A).
Integrated Advanced Microwave Sounding Unit-A (AMSU-A). Engineering Test Report: Radiated Emissions and SARR, SARP, DCS Receivers, Link Frequencies EMI Sensitive Band Test Results, AMSU-A2, S/N 108, 08
NASA Technical Reports Server (NTRS)
Valdez, A.
This is the Engineering Test Report, Radiated Emissions and SARR, SARP, DCS Receivers, Link Frequencies EMI Sensitive Band Test Results, AMSU-A2, S/N 108, for the Integrated Advanced Microwave Sounding Unit-A (AMSU-A).
Integrated Advanced Microwave Sounding Unit-A (AMSU-A). Engineering Test Report: Radiated Emissions and SARR, SARP, DCS Receivers, Link Frequencies EMI Sensitive Band Test Results, AMSU-A1, S/N 109
NASA Technical Reports Server (NTRS)
Valdez, A.
This is the Engineering Test Report, Radiated Emissions and SARR, SARP, DCS Receivers, Link Frequencies EMI Sensitive Band Test Results, AMSU-A1, S/N 109, for the Integrated Advanced Microwave Sounding Unit-A (AMSU-A).
Spontaneous emission from radiative chiral nematic liquid crystals at the photonic band-gap edge: An investigation into the role of the density of photon states near resonance
NASA Astrophysics Data System (ADS)
Mavrogordatos, Th. K.; Morris, S. M.; Wood, S. M.; Coles, H. J.; Wilkinson, T. D.
In this article, we investigate the spontaneous emission properties of radiating molecules embedded in a chiral nematic liquid crystal, under the assumption that the electronic transition frequency is close to the photonic edge mode of the structure, i.e., at resonance. We take into account the transition broadening and the decay of electromagnetic field modes supported by the so-called ōmirrorlessöcavity. We employ the Jaynes-Cummings Hamiltonian to describe the electron interaction with the electromagnetic field, focusing on the mode with the diffracting polarization in the chiral nematic layer. As known in these structures, the density of photon states, calculated via the Wigner method, has distinct peaks on either side of the photonic band gap, which manifests itself as a considerable modification of the emission spectrum. We demonstrate that, near resonance, there are notable differences between the behavior of the density of states and the spontaneous emission profile of these structures. In addition, we examine in some detail the case of the logarithmic peak exhibited in the density of states in two-dimensional photonic structures and obtain analytic relations for the Lamb shift and the broadening of the atomic transition in the emission spectrum. The dynamical behavior of the atom-field system is described by a system of two first-order differential equations, solved using the Green's-function method and the Fourier transform. The emission spectra are then calculated and compared with experimental data.
Search for the OH (X(2)Pi) Meinel band emission in meteors as a tracer of mineral water in comets: detection of N(2)(+) (A-X)
NASA Technical Reports Server (NTRS)
Jenniskens, Peter; Laux, Christophe O.
We report the discovery of the N(2)(+) A-X Meinel band in the 780-840 nm meteor emission from two Leonid meteoroids that were ejected less than 1000 years ago by comet 55P/Tempel-Tuttle. Our analysis indicates that the N(2)(+) molecule is at least an order of magnitude less abundant than expected, possibly as a result of charge transfer reactions with meteoric metal atoms. This new band was found while searching for rovibrational transitions in the X(2)Pi electronic ground state of OH (the OH Meinel band), a potential tracer of water bound to minerals in cometary matter. The electronic A-X transition of OH has been identified in other Leonid meteors. We did not detect this OH Meinel band, which implies that the excited A state is not populated by thermal excitation but by a mechanism that directly produces OH in low vibrational levels of the excited A(2)Sigma state. Ultraviolet dissociation of atmospheric or meteoric water vapor is such a mechanism, as is the possible combustion of meteoric organics.
SIMULTANEOUS K- AND L-BAND SPECTROSCOPY OF Be STARS: CIRCUMSTELLAR ENVELOPE PROPERTIES FROM HYDROGEN EMISSION LINES
Granada, A.; Arias, M. L.; Cidale, L. S., E-mail: firstname.lastname@example.com [Facultad de Ciencias Astronomicas y Geofisicas, Universidad Nacional de La Plata, Paseo del Bosque S/N, La Plata, Buenos Aires (Argentina)
We present medium-resolution K- and L-band spectra of a sample of eight Be stars, obtained with Gemini/NIRI. The IR K and L bands contain many lines of different hydrogen series that are used as a diagnosis to the physical conditions in the circumstellar environments. We make an analysis on the optical depths of the line-forming regions based on the intensity ratios of Pf{gamma} and Br{alpha} lines, the behavior of Humphreys' series, and the fluxes of Br{alpha} and Br{gamma} lines. All our targets show spectroscopic and photometric long-term variability; thus, time-resolved K- and L-band spectroscopy is an ideal tool for studying the structure and evolution of the innermost regions of the envelope and to test models on the disk-forming mechanism. We note that the instrumental configuration used allowed us to obtain good quality IR observations and to take profit of Gemini band 3 observing time (allocation time for ranked programs in which the observing conditions are relaxed).
Simultaneous K- and L-band Spectroscopy of Be Stars: Circumstellar Envelope Properties from Hydrogen Emission Lines
NASA Astrophysics Data System (ADS)
Granada, A.; Arias, M. L.; Cidale, L. S.
We present medium-resolution K- and L-band spectra of a sample of eight Be stars, obtained with Gemini/NIRI. The IR K and L bands contain many lines of different hydrogen series that are used as a diagnosis to the physical conditions in the circumstellar environments. We make an analysis on the optical depths of the line-forming regions based on the intensity ratios of Pf? and Br? lines, the behavior of Humphreys' series, and the fluxes of Br? and Br? lines. All our targets show spectroscopic and photometric long-term variability; thus, time-resolved K- and L-band spectroscopy is an ideal tool for studying the structure and evolution of the innermost regions of the envelope and to test models on the disk-forming mechanism. We note that the instrumental configuration used allowed us to obtain good quality IR observations and to take profit of Gemini band 3 observing time (allocation time for ranked programs in which the observing conditions are relaxed). Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (USA), the Science and Technology Facilities Council (UK), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministķrio da CiĻncia e Tecnologia (Brazil), and Ministerio de Ciencia, TecnologĒa e Innovaci¾n Productiva (Argentina).
Photodissociation dynamics and emission spectroscopy of H2S in its first absorption band - A time dependent quantum mechanical study
Richard N. Dixon; C. Clay Marston; Gabriel G. Balint-Kurti
A theoretical study of the photodissociation dynamics of H2S in its first absorption band is presented. The potential energy surfaces underlying the dynamics of the breakup process have been modeled so as to reproduce the principal features of all the available experimental data. The modeling is performed using time dependent quantum dynamical methods and involves the exact numerical solution of
Carbon stars with alpha-C:H emission
NASA Technical Reports Server (NTRS)
Gerbault, Florence; Goebel, John H.
Many carbon stars in the IRS low resolution spectra (LRS) catalog were found which display emission spectra that compare favorable with the absorption spectrum of alpha-C:H. These stars have largely been classified as 4X in the LRS which has led to their interpretation by others in terms of displaying a mixture of the UIRF's 8.6 micron band and SiC at 11.5 microns. It was also found that many of these stars have a spectral upturn at 20+ microns which resembles the MgS band seen in carbon stars and planetary nebulae. It was concluded that this group of carbon stars will evolve into planetary nebulae like NGC 7027 and IC 418. In the presence of hard ultraviolet radiation the UIRF's will light up and be displayed as narrow emission bands on top of the broad alpha-C:H emission bands.
The first identification of C2 emission bands in comet Scorichenko-George (1989e1) spectrum
NASA Technical Reports Server (NTRS)
Churyumov, Klim I.; Chorny, G. F.
Wave lengths from 360 emissions within the spectral range lambda lambda 3380-6290 A in the spectrum of the comet Scorichenko-George, obtained with the help of the TV spectral scanner of a 6-meter reflector BTA (in Special AO) have been determined. The CN, C2, C3, NH, CH, CO, Na, NH2, N2(+), CO(+), CO2(+), H2O(+), and C2(-) emissions have been identified. For the first time, it has been shown that emissions of C2(-) (the transitions 0-0, 0-1, et al.) in the cometary spectrum possibly exist. Molecular ions C2(-) column density with cross-section 1 sq cm is N = 1.44 10(exp -12) cm(exp -2) and their upper limits of gas C2(-) productivity is Q(C2(-)) = 2 10(exp 28) c(exp -1).
Operation of an ungated diamond field-emission array cathode in a L-band radiofrequency electron source
Piot, P. [Northern Illinois Center for Accelerator and Detector Development and Department of Physics, Northern Illinois University, DeKalb, Illinois 60115 (United States); Accelerator Physics Center, Fermi National Accelerator Laboratory, Batavia, Illinois 60510 (United States); Brau, C. A.; Gabella, W. E.; Ivanov, B.; Mendenhall, M. H. [Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235 (United States); Choi, B. K. [Department of Electrical Engineering and Computer Science, Vanderbilt University, Nashville, Tennessee 37235 (United States); Vanderbilt Institute of Nanoscale Science and Engineering, Vanderbilt University, Nashville, Tennessee 37235 (United States); Blomberg, B.; Mihalcea, D.; Panuganti, H. [Northern Illinois Center for Accelerator and Detector Development and Department of Physics, Northern Illinois University, DeKalb, Illinois 60115 (United States); Jarvis, J. [Advanced Energy Systems, Inc., Medford, New York 11763 (United States); Prieto, P.; Reid, J. [Accelerator Division, Fermi National Accelerator Laboratory, Batavia, Illinois 60510 (United States)
We report on the operation of a field-emitter-array cathode in a conventional L-band radio-frequency electron source. The cathode consisted of an array of ?10{sup 6} diamond tips on pyramids. Maximum current on the order of 15?mA was reached and the cathode did not show appreciable signs of fatigue after weeks of operation. The measured Fowler-Nordheim characteristics, transverse beam density, and current stability are discussed.
Using JERS-1 L-band SAR to estimate methane emissions from the Jau┤ river floodplain (Amazon\\/Brazil)
A. Rosenqvist; B. R. Forsberg; T. Pimentel; J. E. Richey
Demonstrates how multi-temporal JERS-1 LHH band SAR data can be used to derive detailed spatial and temporal information about wetland distributions and improve estimates of methane fluxes from these environments. Within the framework of the NASDA-led Global Rain Forest Mapping (GRFM) project, a part of the Jau┤ river in the central part of the Amazon basin, was monitored during two
Optically trapped atomic resonant devices for narrow linewidth spectral imaging
NASA Astrophysics Data System (ADS)
Qian, Lipeng
This thesis focuses on the development of atomic resonant devices for spectroscopic applications. The primary emphasis is on the imaging properties of optically thick atomic resonant fluorescent filters and their applications. In addition, this thesis presents a new concept for producing very narrow linewidth light as from an atomic vapor lamp pumped by a nanosecond pulse system. This research was motivated by application for missile warning system, and presents an innovative approach to a wide angle, ultra narrow linewidth imaging filter using a potassium vapor cell. The approach is to image onto and collect the fluorescent photons emitted from the surface of an optically thick potassium vapor cell, generating a 2 GHz pass-band imaging filter. This linewidth is narrow enough to fall within a Fraunhefer dark zone in the solar spectrum, thus make the detection solar blind. Experiments are conducted to measure the absorption line shape of the potassium resonant filter, the quantum efficiency of the fluorescent behavior, and the resolution of the fluorescent image. Fluorescent images with different spatial frequency components are analyzed by using a discrete Fourier transform, and the imaging capability of the fluorescent filter is described by its Modulation Transfer Function. For the detection of radiation that is spectrally broader than the linewidth of the potassium imaging filter, the fluorescent image is seen to be blurred by diffuse fluorescence from the slightly off resonant photons. To correct this, an ultra-thin potassium imaging filter is developed and characterized. The imaging property of the ultra-thin potassium imaging cell is tested with a potassium seeded flame, yielding a resolution image of ś 20 lines per mm. The physics behind the atomic resonant fluorescent filter is radiation trapping. The diffusion process of the resonant photons trapped in the atomic vapor is theoretically described in this thesis. A Monte Carlo method is used to simulate the absorption and fluorescence. The optimum resolution of the fluorescent image is predicted by simulation. Radiation trapping is also shown to be useful for the generation of ultra-narrow linewidth light from an atomic vapor flash lamp. A 2 nanosecond, high voltage pulse is used to excite low pressure mercury vapor mixed with noble gases, producing high intensity emission at the mercury resonant line at 253.7 nm. With a nanosecond pumping time and high electrical current, the radiation intensity of the mercury discharge is increased significantly compared to a normal glow discharge lamp, while simultaneously suppressing the formation of an arc discharge. By avoiding the arc discharge, discrete spectral lines of mercury were kept at narrow bandwidth. Due to radiation trapping, the emission linewidth from the nanosecond mercury lamp decreases with time and produces ultra-narrow linewidth emission 100 ns after of the excitation, this linewidth is verified by absorption measurements through low pressure mercury absorption filter. The lamp is used along with mercury absorption filters for spectroscopic applications, including Filtered Rayleigh Scattering with different CO2 pressures and Raman scattering from methanol.
Neptune's non-thermal radio emissions - Phenomenology and source locations
NASA Technical Reports Server (NTRS)
Rabl, Gerald K. F.; Ladreiter, H.-P.; Rucker, Helmut O.; Kaiser, Michael L.
During the inbound and the outbound leg of Voyager 2's encounter with Neptune, the Planetary Radio Astronomy (PRA) experiment aboard the spacecraft detected short radio bursts at frequencies within the range of about 500-1300 kHz, and broad-banded smoothly varying emission patterns within the frequency range from about 40-800 kHz. Both emissions can be described in terms of a period of 16.1 hours determining Neptune's rotation period. Furthermore, just near closest approach, a narrow-banded smoothly varying radio component was observed occurring between 600 and 800 kHz. After giving a brief overview about some general characteristics of Neptune's nonthermal radio emission, the source locations of Neptune's emission components are determined, using an offset tilted dipole model for Neptune's magnetic field. Assuming that the emission originates near the electron gyrofrequency a geometrical beaming model is developed in order to fit the observed emission episodes.
Neptune's non-thermal radio emissions - Phenomenology and source locations
NASA Astrophysics Data System (ADS)
Rabl, Gerald K. F.; Ladreiter, H.-P.; Rucker, Helmut O.; Kaiser, Michael L.
During the inbound and the outbound leg of Voyager 2's encounter with Neptune, the Planetary Radio Astronomy (PRA) experiment aboard the spacecraft detected short radio bursts at frequencies within the range of about 500-1300 kHz, and broad-banded smoothly varying emission patterns within the frequency range from about 40-800 kHz. Both emissions can be described in terms of a period of 16.1 hours determining Neptune's rotation period. Furthermore, just near closest approach, a narrow-banded smoothly varying radio component was observed occurring between 600 and 800 kHz. After giving a brief overview about some general characteristics of Neptune's nonthermal radio emission, the source locations of Neptune's emission components are determined, using an offset tilted dipole model for Neptune's magnetic field. Assuming that the emission originates near the electron gyrofrequency a geometrical beaming model is developed in order to fit the observed emission episodes.
Simultaneous two-band laser emissions and three primary color outputs in the superradiant mode from dye mixtures
Saito, Y.; Nomura, A.; Kano, T.
A dye mixture of coumarin 460, disodium fluorescein, and nile blue 690 perchrolate was excited by a nitrogen laser. Simultaneous laser emissions in two spectra regions (blue and green, green and red, red and blue) were obtained in each of the two dye mixtures. Furthermore, simultaneous three primary color outputs in a superradiant mode from three dye mixtures were observed.
Linking visible absorption bands and far-IR emission features trough MonteCarlo simulations: a quantitative test of the PAHs DIBs-UIBs hypothesis
NASA Astrophysics Data System (ADS)
Malloci, Giuliano; Mulas, Giacomo; Benvenuti, Piero
One important aspect which is seldom emphasized on the so-called ``strong'' Polycyclic Aromatic Hydrocarbons (PAHs) hypothesis is that the failure to identify the vibronic absorption bands of PAH cations and/or radicals in the visible would cast strong doubts on the applicability of the PAH model for the UIBs and on their alleged presence in the ISM at all. In order to quantitatively assess this link between DIBs and UIBs, we modeled the interaction of a big, isolated PAH molecule with the interstellar radiation field, which in the PAH model is supposed to govern both the intensities of the UIBs and the spectral profile of its vibronic absorption bands, as given by its rotational envelope. We used a MonteCarlo approach, tailored on the properties of a specific molecule and on the interstellar environment it is embedded in. As a ``proof of concept'' case, we considered the cation of a middle sized PAH, namely the ovalene molecule (C32H14+): we obtained the expected rotational profile of its first allowed electronic transition D0 to D2, which falls at about 9700┼, as a function of a grid of widely different ambient radiation fields. Our results, which can be expected to hold for other similar PAHs, show that the band profiles are remarkably insensitive to both the ambient conditions and the assumed values of some key molecular parameters. This provides a sound quantitative foundation to the hypothesis of PAHs as DIB carriers, since the profile invariance with respect to diverse physical environments is one of the most prominent observed DIB properties. We also obtained a quantitative relation between the modeled ``DIB'' and the far infrared emission bands, both of which are a peculiar fingerprint of each and every specific molecule. This result provides a very powerful criterion for the identification of specific PAHs, both in the presently available ISO data and in those of the forthcoming SIRTF mission.
Analysis of chorus emissions at Jupiter
NASA Astrophysics Data System (ADS)
Coroniti, F. V.; Scarf, F. L.; Kennel, C. F.; Kurth, W. S.
The emissions in the chorus frequency band which were detected on the Voyager 1 inbound pass between about ten and six Jupiter radii are surveyed. An overview of the plasma and wave observations during the inbound pass is presented and the spatial regions in which chorus band signals were observed are discussed. A series of wide-band frequency-time frames which characterize the onset of two observed intervals of chorus band activity is displayed. A detailed examination is made of the spectra for rising chorus which sweeps upward in frequency from 0.2 to 0.5 times the electron cyclotron frequency f(c). Two temporally successive wide-band frames in which several types of chorus band emissions were observed are discussed. The spatial morphology of chorus is discussed in terms of the electron energies which resonate with whistler mode waves. A recent theory of chorus generation is reviewed along with theories and a model explaining the narrow-band emissions above f(c)/2.
Dual-Band Plasmonic Enhancement of Ag-NS@SiO 2 on Gain MediumÆs Spontaneous Emission
Jiunn-Woei Liaw; Chuan-Li Liu; Mao-Kuen Kuo
We present a theoretical study on plasmonic enhancement of molecular fluorescence near a nanocomposite, Ag nanoshell (Ag-NS)\\u000a coated by a gain medium of molecule-doped SiO2 layer. We use an average enhancement factor (AEF), which considers contributions from all possible orientations and locations\\u000a of molecules in the silica layer to estimate the overall performance of Ag-NS@SiO2 at specific excitation and emission
PIC Simulations of Banded Chorus Events from Van Allen Probes Observations
NASA Astrophysics Data System (ADS)
Fu, X.; Cowee, M.; Friedel, R. H.; Gary, S. P.; Hospodarsky, G. B.; Kletzing, C.; Liu, K.; MacDonald, E.; Reeves, G. D.; Skoug, R. M.; Winske, D.
Banded chorus emissions are whistler waves with two bands separated by a narrow gap at 0.5?ce (?ce is the elctron gyro-frequency) in the frequency spectrum, often observed in the inner magnetosphere. The physical reason for the gap is still puzzling the space community. To better understand banded chorus generation, we identify occurrences of banded chorus in the Van Allen Probes EMFISIS data. Prameters derived from observations are used as initial conditions for our linear theory and nonlinear particle-in-cell simulations. By comparing our simulation results with electron pitch angle distributions from HOPE and wave spectra from EMFISIS, we will test some hypotheses for generation of banded chorus. LA-UR-13-26132.
Theory of magnetic susceptibility of narrow gap semiconductors
Leonid Falkovsky; Moscow V
A theory of magnetic susceptibility of narrow gap semiconductors of the Pb1¢xSnxTe and Hg1¢xCdxTe type is developped. A singular contribution of states in the vicinity of the extreme points of the bands separated by a narrow forbidden gap is singled out. It depends on the magnitude of the gap, i.e. on the composition of the alloy and also on the
Confinement effect of laser ablation plume in liquids probed by self-absorption of C{sub 2} Swan band emission
Sakka, Tetsuo; Saito, Kotaro; Ogata, Yukio H. [Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011 (Japan)
The (0,0) Swan band of the C{sub 2} molecules in a laser ablation plume produced on the surface of graphite target submerged in water was used as a probe to estimate the density of C{sub 2} molecules in the plume. Observed emission spectra were reproduced excellently by introducing a self-absorption parameter to the theoretical spectral profile expected by a rotational population distribution at a certain temperature. The optical density of the ablation plume as a function of time was determined as a best-fit parameter by the quantitative fitting of the whole spectral profile. The results show high optical densities for the laser ablation plume in water compared with that in air. It is related to the plume confinement or the expansion, which are the important phenomena influencing the characteristics of laser ablation plumes in liquids.
Constraining the structure of the Narrow-Line Region of nearby QSO2s
NASA Astrophysics Data System (ADS)
Storchi-Bergmann, Thaisa
The Narrow-Line Region (NLR) of Active Galactic Nuclei (AGN) is the only resolved region of AGN, observed via high excitation ionized gas emission that extends from hundred to kiloparsec scales in the host galaxies. In nearby AGN (z<0.03), the NLR is known to present an elongated or cone-like morphology seen in type 2 AGN, and circular morphology in type 1 AGN, supporting the Unified Model. Nevertheless, at somewhat higher z's (~ 0.5) recent ground-based studies have found mostly circular morphologies in observations of QSO2s (obscured QSOs). But at the corresponding distances of these objects, ground-based observations lack the necessary angular resolution to fully resolve the NLRs. It is not clear if the intrinsic NLR morphology changes for more luminous AGN or this is an effect of the atmospheric seeing. Only with HST we will be able to resolve the NLR morphology down to a few hundred parsec scales in the galaxy. We thus propose a "mini-survey" of the NLRs by obtaining narrow-band images in [OIII] and Halpha+[NII] of a sample of nearby QSO2s spanning the redshift range 0.05
Ring resonator based narrow-linewidth semiconductor lasers
NASA Technical Reports Server (NTRS)
Ksendzov, Alexander (Inventor)
The present invention is a method and apparatus for using ring resonators to produce narrow linewidth hybrid semiconductor lasers. According to one embodiment of the present invention, the narrow linewidths are produced by combining the semiconductor gain chip with a narrow pass band external feedback element. The semi conductor laser is produced using a ring resonator which, combined with a Bragg grating, acts as the external feedback element. According to another embodiment of the present invention, the proposed integrated optics ring resonator is based on plasma enhanced chemical vapor deposition (PECVD) SiO.sub.2 /SiON/SiO.sub.2 waveguide technology.
ELF noise bands associated with auroral electron precipitation.
NASA Technical Reports Server (NTRS)
Gurnett, D. A.; Frank, L. A.
Observation of a new type of ELF noise band that is closely associated with low-energy auroral electron precipitation. These observations have been made at relatively low altitudes (less than 3000 km) with the polar-orbiting satellite Injun 5. The noise bands typically have a center frequency of 100 to 300 Hz and often appear to consist of many nearly monochromatic bursts, typically of a few seconds' duration, superimposed to produce the observed noise band. These ELF noise bands are observed only in a relatively narrow range of latitudes (a few degrees) in the auroral zone and are almost always associated with intense fluxes of precipitating electrons with energies from a few hundred electron volts to several kiloelectron volts. On the dayside of the magnetosphere the region where the ELF noise bands and the associated low-energy electron precipitation are observed has been identified as the polar cusp. In considering the possible explanations of these ELF noise bands, it is noted that the spectral characteristics of this noise are very similar to a type of narrowband electromagnetic noise called 'lion's roar,' which has been observed at much higher altitudes in the magnetosheath with the satellite Ogo 5. It is suggested that the ELF noise bands observed at low altitudes with Injun 5 are caused by lion's roar emissions that have propagated down 'open' magnetic-field lines to low altitudes from the magnetosheath region.
Resonant emission from the B870 exciton state and electron?phonon coupling in the LH2 antenna chromoprotein
NASA Astrophysics Data System (ADS)
Rõtsep, Margus; Freiberg, Arvi
Fluorescence of the peripheral LH2 antenna complex from the photosynthetic bacterium Rhodobacter sphaeroides has been studied at 5 K upon selective excitation into the B870 exciton absorption band. Heterogeneous nature of the LH2 emission band has been confirmed by a double spectral selection technique simultaneously utilizing hole burning and fluorescence line narrowing spectroscopy. The phonon structure of the spectra related to the B870 band has been analyzed resulting in a genuine single-exciton state absorption/emission profile. The total electron-phonon coupling strength S=0.8▒0.2, larger than previously assumed, has been determined.
NASA Technical Reports Server (NTRS)
1999-01-01This brief three-frame movie of the Moon was made from three Cassini narrow-angle images as the spacecraft passed by the Moon on the way to its closest approach with Earth on August 17, 1999. The purpose of this particular set of images was to calibrate the spectral response of the narrow-angle camera and to test its 'on-chip summing mode' data compression technique in flight. From left to right, they show the Moon in the green, blue and ultraviolet regions of the spectrum in 40, 60 and 80 millisecond exposures, respectively. All three images have been scaled so that the brightness of Crisium basin, the dark circular region in the upper right, is the same in each image. The spatial scale in the blue and ultraviolet images is 1.4 miles per pixel (2.3 kilometers). The original scale in the green image (which was captured in the usual manner and then reduced in size by 2x2 pixel summing within the camera system) was 2.8 miles per pixel (4.6 kilometers). It has been enlarged for display to the same scale as the other two. The imaging data were processed and released by the Cassini Imaging Central Laboratory for Operations (CICLOPS) at the University of Arizona's Lunar and Planetary Laboratory, Tucson, AZ. Photo Credit: NASA/JPL/Cassini Imaging Team/University of Arizona Cassini, launched in 1997, is a joint mission of NASA, the European Space Agency and Italian Space Agency. The mission is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Office of Space Science, Washington DC. JPL is a division of the California Institute of Technology, Pasadena, CA.
The broad-band X-ray spectrum of a QSO sample
NASA Technical Reports Server (NTRS)
Worrall, D. M.; Marshall, F. E.
A sample of 25 QSOs was used to investigate the average spectrum between the soft X-ray energy band of the Einstein Observatory image proportional counter, and the higher energy band of the HEAO 1 A2 experiment. The spectrum is similar to thoe exhibited by Seyfert galaxies and narrow emission line galaxies above 2 keV. The spectrum is soft enough that if these objects are typical of the higher redshift, more radio-quiet QSOs, then it is possible to exclude QSOs as being the dominant origin of the diffuse X-ray background.
Tunable Enhancement of High Harmonic Emission from Laser Solid Interactions
Dromey, B.; Adams, D.; Kar, S.; Markey, K.; Geissler, M.; Zepf, M. [Department of Physics and Astronomy, Queens University Belfast, BT7 INN (United Kingdom); Rykovanov, S. G. [MPQ Garching, Hans-Kopfermann-Strasse l, D-85748 Garching (Germany); Moscow Physics Engineering Institute, Kashirskoe Shosse 31, 115409 Moscow (Russian Federation); Hoerlein, R. [MPQ Garching, Hans-Kopfermann-Strasse l, D-85748 Garching (Germany); Sektion Physik der Ludwig-Maximilians-Universitat Milnchen, Am Coulombwall 1, D-85748 Garching (Germany); Nomura, Y.; Tsakiris, G. D. [MPQ Garching, Hans-Kopfermann-Strasse l, D-85748 Garching (Germany); Carroll, D. C.; McKenna, P. [SUPA, Department of Physics, University of Strathclyde, Glasgow, G4 ONG (United Kingdom); Foster, P. S.; Neely, D. [Central Laser Facility, STFC Rutherford Appleton Laboratory, Chilton, Didcot, OXll OQX (United Kingdom)
Coherent wake emission is a unique source of extreme ultraviolet radiation and has been recently shown to provide the basis for intense attosecond light. Here we present a novel scheme, supported by particle-in-cell simulations, demonstrating that enhancement and spectral control of the coherent wake emission signal can be achieved by modifying the interaction plasma density ramp. Significant tunable enhancement of harmonic emission is verified experimentally, with factors of >50 in relative signal increase achieved in a narrow band of harmonics at the cutoff frequency.
Tunable enhancement of high harmonic emission from laser solid interactions.
Dromey, B; Rykovanov, S G; Adams, D; H÷rlein, R; Nomura, Y; Carroll, D C; Foster, P S; Kar, S; Markey, K; McKenna, P; Neely, D; Geissler, M; Tsakiris, G D; Zepf, M
Coherent wake emission is a unique source of extreme ultraviolet radiation and has been recently shown to provide the basis for intense attosecond light. Here we present a novel scheme, supported by particle-in-cell simulations, demonstrating that enhancement and spectral control of the coherent wake emission signal can be achieved by modifying the interaction plasma density ramp. Significant tunable enhancement of harmonic emission is verified experimentally, with factors of >50 in relative signal increase achieved in a narrow band of harmonics at the cutoff frequency. PMID:19658870
Search for narrow energy-shifted lines in AGN spectra in the XMM-Newton archive
NASA Astrophysics Data System (ADS)
Longinotti, A. L.; Bianchi, S.; Guainazzi, M.; Roa, J.; Santos-Lleo, M.
Thanks to the large effective area and the spectral resolution of current X-ray satellites, the detection of X-ray narrow spectral features in the 5-7 keV band is becoming commonplace in many AGN observations. Such lines, both in emission and in absorption, are mostly interpreted as arising from Iron atoms. When observed with some displacement from their rest frame position, these lines carry the potential to study the motion of circumnuclear gas in AGN, providing a diagnostic of the effects of the gravitational field of the central black hole. These narrow features have been often found with marginal statistical significance. A systematic search for narrow features in type1 AGN is being performed on all spectra available in the XMM-Newton archive with the aim to estimate the significance of the features with Monte Carlo simulations of synthetic spectra. The project and preliminary results are presented. http://xmm.esac.esa.int/external/xmm_data_acc/xsa/index.shtml
Thermal effects on light-emission properties of GaN LEDs grown by metal-organic vapor phase epitaxy
Tohru Honda; Toshiaki Kobayashi; Shinichi Egawa; Masaru Sawada; Koichi Sugimoto; Taichi Baba
Photoluminescence (PL) spectra of GaN layers grown on sapphire substrates by metal-organic vapor phase epitaxy (MOVPE) were observed at temperatures from RT to 500K. The spectra include the near-band-edge emission (NBE) and yellow luminescence (YL). The peak energy of the NBE is shifted towards lower energy with increasing observed temperature. UV light-emitting diodes (LEDs) utilizing band-gap narrowing due to thermal