text:
Electrodynamic forces of the cross-connected figure-eight null-flux coil suspension system
He, J.L.; Rote, D.M.; Coffey, H.T.
This paper analyzes the cross-connected figure-eight null-flux coil suspension system for maglev vehicles on the basis of dynamic circuit theory. The equivalent circuits and general magnetic force expressions for the system are developed. Simple analytical formulas for the magnetic force partitions on the basis of harmonic approximation are presented, and numerical results are also included.
Electrodynamic forces of the cross-connected figure-eight null-flux coil suspension system
He, J.L.; Rote, D.M.; Coffey, H.T.
This paper analyzes the cross-connected figure-eight null-flux coil suspension system for maglev vehicles on the basis of dynamic circuit theory. The equivalent circuits and general magnetic force expressions for the system are developed. Simple analytical formulas for the magnetic force partitions on the basis of harmonic approximation are presented, and numerical results are also included.
Computer modeling and experimental verification of figure-eight-shaped null-flux coil suspension system
He, J.L.; Mulcahey, T.M.; Rote, D.M.; Kelly, T.
This report discusses the computer modeling and experimental verification of the magnetic forces associated with a figure-eight-shaped null-flux coil suspension system. A set of computer codes called COILGDWY, were developed on the basis of the dynamic circuit model and verified by means of a laboratory model. The experimental verification was conducted with a rotating PVC drum, the surface of which held various types of figure-eight-shaped null-flux coils that interacted with a stationary permanent magnet. The transient and dynamic magnetic forces between the stationary magnet and the rotating conducting coils were measured and compared with results obtained from the computer model. Good agreement between the experimental results and computer simulations was obtained. The computer model can also be used to calculate magnetic forces in a large-scale magnetic-levitation system.
Forces on a magnet moving past figure-eight coils
Mulcahy, T.H.; He, Jianliang; Rote, D.M. (Argonne National Lab., IL (United States)); Rossing, T.D. (Northern Illinois Univ., De Kalb, IL (United States). Dept. of Physics)
For the first time, the lift, drag, and guidance forces acting on a permanent magnet are measured as the magnet passes over different arrays of figure-eight (null-flux) coils. The experimental results are in good agreement with the predictions of dynamic circuit theory, which is used to explain more optimal coil arrays.
Forces on a magnet moving past figure-eight coils
Mulcahy, T.H.; He, Jianliang; Rote, D.M. [Argonne National Lab., IL (United States); Rossing, T.D. [Northern Illinois Univ., De Kalb, IL (United States). Dept. of Physics
For the first time, the lift, drag, and guidance forces acting on a permanent magnet are measured as the magnet passes over different arrays of figure-eight (null-flux) coils. The experimental results are in good agreement with the predictions of dynamic circuit theory, which is used to explain more optimal coil arrays.
78 FR 25577 - Safety Zone, Figure Eight Causeway Channel; Figure Eight Island, NC
Federal Register 2010, 2011, 2012, 2013, 2014
...restricts access to Figure Eight Causeway Channel...this rule will not be significant because: (i) The...rule will not have a significant economic impact on a...transit or anchor in the Figure Eight Causeway Channel...regulation will not have a significant impact on a...
Minerbe, Vincent
BRANCHED SPHERICAL CR STRUCTURES ON THE COMPLEMENT OF THE FIGURE EIGHT KNOT. ELISHA FALBEL representa- tions from the complement of the figure eight knot into PU(2, 1), we call them 1 and 2. We make eight knot complement as a surface bundle over the circle, the behaviour of of the fundamental group
Generation of long broadband pulses with a figure-eight fiber laser
J. C. Hernandez-Garcia; O. Pottiez; R. Grajales-Coutińo; B. Ibarra-Escamilla; E. A. Kuzin; J. M. Estudillo-Ayala; J. Gutierrez-Gutierrez
In this paper we performed the experimental and numerical study of a passively mode-locked fiber laser that generates packets\\u000a of sub-picosecond pulses instead of individual pulses. The proposed configuration is a figure-eight fiber laser scheme, which\\u000a includes a Nonlinear Optical Loop Mirror with polarization asymmetry inserted into a ring cavity. No experimental evidence\\u000a of self-starting mode locking operation of the
Computer model simulation of null-flux magnetic suspension and guidance
He, Jianliang; Rote, D.M.
This paper discusses the magnetic force computations in a null-flux suspension system using dynamic circuit theory. A computer simulation model that can be used to compute magnetic forces and predict the system performance is developed on the basis of dynamic circuit theory. Numerical examples are presented to demonstrate the application of the model. The performance of the null-flux suspension system is simulated and discussed. 8 refs.
Computer model simulation of null-flux magnetic suspension and guidance
He, Jianliang; Rote, D.M.
This paper discusses the magnetic force computations in a null-flux suspension system using dynamic circuit theory. A computer simulation model that can be used to compute magnetic forces and predict the system performance is developed on the basis of dynamic circuit theory. Numerical examples are presented to demonstrate the application of the model. The performance of the null-flux suspension system is simulated and discussed. 8 refs.
Noise-like pulse trapping in a figure-eight fiber laser.
Luo, Ai-Ping; Luo, Zhi-Chao; Liu, Hao; Zheng, Xu-Wu; Ning, Qiu-Yi; Zhao, Nian; Chen, Wei-Cheng; Xu, Wen-Cheng
We report on the trapping of noise-like pulse in a figure-eight fiber laser mode locked by nonlinear amplifier loop mirror (NALM). After achievement of noise-like vector pulse, it was found that the wavelength shift of the two resolved polarization components responsible for the pulse trapping was very sensitive to the cavity birefringence. By properly rotating the polarization controllers (PCs), the wavelength shift could be up to 4.8 nm, which is much larger than that of conventional soliton trapping. The observed results would shed some light on the fundamental physics of noise-like pulse as well as its vector features in fiber lasers. PMID:25969083
Electromagnetic characteristics of eccentric figure-eight coils for transcranial magnetic stimulation: A numerical study
NASA Astrophysics Data System (ADS)
Kato, Takuya; Sekino, Masaki; Matsuzaki, Taiga; Nishikawa, Atsushi; Saitoh, Youichi; Ohsaki, Hiroyuki
Repetitive transcranial magnetic stimulation (rTMS) is effective for treatment of several neurological and psychiatric diseases. We proposed an eccentric figure-eight coil, which induces strong eddy currents in the target brain tissue. In this study, numerical analyses were carried out to obtain magnetic field distribution of the eccentric figure-eight coil and eddy current in the brain. The analyses were performed with various coil design parameters, such as the outer and inner diameters and number of turns, to investigate the influence of these parameters on the coil characteristics. Increases in the inner diameter, outer diameter, and number of turns caused increases in the maximum eddy current densities. Coil inductance, working voltage, and heat generation also became higher with the increases in these design parameters. In order to develop a compact stimulator system for use at home, we need to obtain strong eddy current density, keeping the working voltage as low as possible. Our results show that it is effective to enlarge the outer diameter.
Design approaches and parameters for magnetically levitated transport systems. [Null flux suspension (Maglev)
Danby, G.T.; Powell, J.R.
Mechanically levitated transport system approaches are assessed with regard to thrust power needs, track cost, suspension stability, and safety. The null flux suspension appears as the favored approach, having the least thrust power requirements, highest stability, and lowest amount of track material. Various null flux configurations are described together with their operating parameters. The Linear Synchronous Motor (LSM) propulsion system is also described for propelling the suspended vehicles. Cryogenics and superconductivity aspects are discussed and the effect of high T/sub c/ superconductors evaluated. 13 refs., 16 figs., 2 tabs.
Narrow-linewidth double-peak figure-eight passively mode-locked fiber laser
NASA Astrophysics Data System (ADS)
Liu, Xianglian; Li, Xiaohui; Zhang, Wei; Wang, Yishan
We report on the experimental observation of narrow-linewidth double-peak dissipative solitons in a figure-eight Yb-doped passively mode-locked fiber laser in the large net normal cavity dispersion regime. Without any physical bandpass filters in the cavity, stable mode-locking pulses with a duration of 416?ps and a 3?dB bandwidth of 0.3?nm can be directly generated from the laser cavity. The edge-to-edge bandwidth of the spectrum is about 5?nm. The repetition rate of the dissipative solitons is 3.9?MHz. With the increase of pump power, the central wavelength of the dissipative solitons shifts toward a short wavelength and edge-to-edge spectral widths are widened gradually. These phenomena are theoretically explained.
Water Treatment Technology - Cross-Connections.
ERIC Educational Resources Information Center
Ross-Harrington, Melinda; Kincaid, G. David
One of twelve water treatment technology units, this student manual on cross connections provides instructional materials for two competencies. (The twelve units are designed for a continuing education training course for public water supply operators.) The competencies focus on cross connections terminology and control devices. For each…
Vector nature of multi-soliton patterns in a passively mode-locked figure-eight fiber laser.
Ning, Qiu-Yi; Liu, Hao; Zheng, Xu-Wu; Yu, Wei; Luo, Ai-Ping; Huang, Xu-Guang; Luo, Zhi-Chao; Xu, Wen-Cheng; Xu, Shan-Hui; Yang, Zhong-Min
The vector nature of multi-soliton dynamic patterns was investigated in a passively mode-locked figure-eight fiber laser based on the nonlinear amplifying loop mirror (NALM). By properly adjusting the cavity parameters such as the pump power level and intra-cavity polarization controllers (PCs), in addition to the fundamental vector soliton, various vector multi-soliton regimes were observed, such as the random static distribution of vector multiple solitons, vector soliton cluster, vector soliton flow, and the state of vector multiple solitons occupying the whole cavity. Both the polarization-locked vector solitons (PLVSs) and the polarization-rotating vector solitons (PRVSs) were observed for fundamental soliton and each type of multi-soliton patterns. The obtained results further reveal the fundamental physics of multi-soliton patterns and demonstrate that the figure-eight fiber lasers are indeed a good platform for investigating the vector nature of different soliton types. PMID:24921311
Generation of a noiselike soliton molecule induced by a comb filter in a figure-eight fiber laser
NASA Astrophysics Data System (ADS)
Luo, Ai-Ping; Zheng, Xu-Wu; Liu, Meng; Liu, Hao; Zhao, Nian; Ning, Qiu-Yi; Luo, Zhi-Chao; Xu, Wen-Cheng
We report on the generation of a noiselike soliton molecule induced by a comb filter in a figure-eight fiber laser. Despite the noiselike mode-locked operation, there were always several peaks riding on a wide shoulder when the mode-locked operation was obtained; this phenomenon was called the noiselike soliton molecule. It was found that the formation of the noiselike soliton molecule is induced by the intracavity comb filter. The observed results would give further insight towards understanding both the fundamental physics of soliton molecules and the noiselike pulses in passively mode-locked fiber lasers.
Generation and characterization of erbium-Raman noise-like pulses from a figure-eight fibre laser
NASA Astrophysics Data System (ADS)
Santiago-Hernandez, H.; Pottiez, O.; Paez-Aguirre, R.; Ibarra-Villalon, H. E.; Tenorio-Torres, A.; Duran-Sanchez, M.; Ibarra-Escamilla, B.; Kuzin, E. A.; Hernandez-Garcia, J. C.
We report an experimental study of the noise-like pulses generated by a ~300?m long passively mode-locked erbium-doped figure-eight fibre laser. Non-self-starting mode locking yields the formation of ns scale bunches of sub-ps pulses. Depending on birefringence adjustments, noise-like pulses with a variety of temporal profiles and optical spectra are obtained. In particular, for some adjustments the Raman-enhanced spectrum reaches a 10?dB bandwidth of ~130?nm. For the first time to our knowledge, we extract information on the inner structure of the noise-like pulses, using a birefringent Sagnac interferometer as a spectral filter and a nonlinear optical loop mirror as an intensity filter. In particular we show that the different spectral components of the bunch are homogeneously distributed within the temporal envelope of the bunch, whereas the amplitude and/or the density of the sub-pulses present substantial variations along the envelope. In some cases, the analysis reveals the existence of an intermediate level of organization in the structure of the noise-like pulse, between the ns bunch and the sub-ps inner pulses, suggesting that these objects may be even more complex than previously recognized.
Dual-keel electrodynamic Maglev system
He, Jianliang; Rote, D.M.; Wang, Zian; Coffey, H.T.
This paper introduces a new concept for an electrodynamic-suspension maglev system that has a dual-keel arrangement. Each keel consists of a row of superconducting magnets aboard the vehicle. The keels move in troughs in the guideway that are each lined with pairs of figure-eight-shaped null-flux coils. Each pair of null-flux coils is cross-connected to produce null-flux suspension and guidance force. The cross-connected figure-eight null-flux coils in each trough are also energized by a three-phase power supply to produce propulsive force. Preliminary analysis shows that the new system has many advantages over other EDS systems in terms of system performance and dynamic stability.
Wavelength-tunable picosecond pulses from a passively mode-locked figure-eight Erbium-doped fiber laser with a Sagnac fiber filter
NASA Astrophysics Data System (ADS)
Ibarra-Escamilla, B.; Pottiez, O.; Haus, J. W.; Kuzin, E. A.; Bello-Jimenez, M.; Flores-Rosas, A.
We experimentally demonstrated a wavelength-tunable passively mode-locked Erbium-doped figure-eight fiber laser. Wide tunability is achieved using a high-birefringence (hi-bi) fiber Sagnac loop. The filter transmission function is controlled by selecting the hi-bi fiber loop length. The output pulses are wavelength tunable over a range from 1525 nm to 1555 nm. The FWHM of the autocorrelation trace is about 3.1 ps and the pulse spectrum has a FWHM of 1.5 nm. The pulse temporal and spectral widths remain constant over the tunable range.
Study of Japanese electrodynamic-suspension maglev systems
He, J.L.; Rote, D.M.; Coffey, H.T. [Argonne National Lab., IL (United States). Center for Transportation Research
This report presents the results of a study of the Japanese MLU magnetic-levitation (maglev) system. The development of the MLU system is reviewed, and the dynamic circuit model then is introduced and applied to the figure-eight-shaped null-flux coil suspension system. Three different types of figure-eight-shaped null-flux suspension systems are discussed in detail: (1) the figure-eight-shaped null-flux coil suspension system without cross-connection; (2) the combined suspension and guidance system; and (3) the combined propulsion, levitation, and guidance system. The electrodynamic-suspension maglev systems developed in Japan seem to be very promising and could result in a commercial application in the near future.
Scalable optical cross-connect switch using micromachined mirrors
Paul M. Hagelin; Uma Krishnamoorthy; Jonathan P. Heritage; Olav Solgaard
This letter describes a free-space optical fiber cross-connect that uses a pair of micromirror arrays to redirect optical beams from an input-fiber array to an output array. This confocal switch architecture is well suited for simultaneous switching of multiple wavelength channels. We show that confocal switches with low insertion loss, low crosstalk, and large port counts can be implemented with
A WDM cross-connected star multihop optical network
MANSOUR I. IRSHID; M. Kavehrad
The authors propose a star topology for multihop lightwave networks in which the conventional N×N passive star coupler is replaced by fixed wavelength division multiplexing (WDM) cross-connects. The proposed topology overcomes three major limitations of the conventional star topology. First, it reduces the number of wavelengths needed in a (p,k) ShuffleNet from kp k+1 wavelengths in the conventional topology to
Cross-connection detection in Australian dual reticulation systems by monitoring inherent fluorescent organic matter
A. C. Hambly; R. K. Henderson; A. Baker; R. M. Stuetz; S. J. Khan
New housing developments are now commonly incorporating dual reticulation water systems for the redistribution of recycled water back to households for non-potable use. Within such distribution systems is the potential for cross-connections between recycled and drinking water pipelines, and a number of such events have been documented both in Australia and internationally. While many cross-connections are unlikely to present a
Cross-connection control of the potable water lines at Oak Ridge National Laboratory
Moore, R.M.
A 1991 independent U.S. Department of Energy (DOE) audit of Oak Ridge National Laboratory (ORNL) identified the need for establishing a cross-connection control program for the potable and nonpotable water systems at the facility. An informal cross-connection policy had been in place for some time, but the formal implementation of a cross-connection program brought together individuals from the Quality Engineering and Inspection Section of the Office of Quality Programs and Inspection, Industrial Hygiene, Health Physics, Plant and Equipment Division, and the Atomic Trade and Labor Council. In January 1994 a Cross-Connection Control Committee was established at ORNL to identify potential and actual cross connections between potable and nonpotable water systems. Potable water is safe to drink, and nonpotable or process water (e.g., sewage, laboratory wastewater, cooling water, and tower water) is not intended for human consumption, washing of the body, or food preparation. The program is intended to conform with the Federal Safe Drinking Water Act Amendment of 1986 and with state and local regulations. Although the Occupational Safety and Health Administration addresses cross-connection functions, it does not define specific program requirements. The program at ORNL is designed to ensure that necessary recommendations are implemented to safeguard all internal and external potable water distribution lines. Program responsibilities include a thorough engineering assessment to (1) identify the potable water lines, (2) identify any existing or potential cross connections, and (3) inspect the integrity of the water lines. If any cross-connection deficiencies are found, corrective actions are initiated according to industry standards.
Impact of SONET digital cross-connect system architecture on distributed restoration
Wu, Tsong-ho; Kobrinski, H.; Lakshman, T.V. (Bellcore, Redbank, NJ (United States))
The viability of distributed control restoration using Digital Cross-Connect Systems (DC's) depends on its capability for restoring services within specified time requirements, and its economics for providing restoration compared to other alternatives. In this paper, we report a Bellcore study for the impact of the DCS architecture on distributed restoration. This study concludes that currently proposed distributed control DCS self-healing schemes may not meet the 2-s restoration objective for large metropolitan Local Exchange Carrier's networks, regardless of the distributed algorithm used, if the present DCS system architecture which uses serial message processing and serial path cross-connection remains unchanged. This paper also discusses several DCS architecture enhancement options, including a parallel processing/cross-connect DCS architecture, which may improve the service restoration time. 20 refs.
Optical path cross-connect node architectures for photonic transport network
Satoru Okamoto; Atsushi Watanabe; Ken-Ichi Sato
This paper explores the optical path cross-connect (OPXC) node architectures that are essential components of the optical path network. Optical path technologies will play a key role in the development of the platform on which the future bandwidth abundant B-ISDN should be created. This paper highlights the wavelength path (WP) and the virtual wavelength path (VWP) technologies, both of which
FBG-Based Bidirectional Optical Cross Connects for Bidirectional WDM Ring Networks
Hanna Yuan; Wen-De Zhong; Weisheng Hu
This paper proposes a new bidirectional optical cross connect (BOXC) using fiber Bragg gratings (FBGs) and optical circulators for bidirectional wavelength-division-multiplexing ring networks. Dynamic and independent wavelength routing is achieved by employing cascaded tunable FBGs. The proposed BOXC requires a small tuning range equal to wavelength channel spacing for tunable FBGs. Therefore, the wavelength count of the proposed BOXC could
WDM cross-connected star topology for the bilayered ShuffleNet
F. Ayadi; J. F. Hayes; M. Kavehrad
A WDM cross-connect is a device based on integrating a two-dimensional array of Bragg diffraction cells. This device can be used in various wavelength routing network applications and it overcomes the major problems related to a conventional broadcast passive star coupler. In this paper, we propose a method of using this device in the implementation of a new logical topology:
A WDM cross-connect star topology for the bilayered ShuffleNet
F. Ayadi; J. F. Hayes; M. Kavehrad
The WDM cross-connect is a device based on integrating a two-dimensional array of Bragg diffraction cells. This device can be used in various wavelength routing network applications and overcomes the major problems related to the conventional star coupler. This device has been proposed for the implementation of the ShuffleNet. In this paper, we propose a method of using this device
A WDM cross-connected star topology for multihop lightwave networks
Mansour I. Irshid; Mohsen Kavehrad
The authors propose a star topology for multihop lightwave networks in which the conventional N×N passive star coupler is replaced by fixed wavelength division multiplexed (WDM) cross connects. The proposed topology overcomes three major limitations of the conventional star topology. First, it reduces the number of wavelengths needed in a (p,k) ShuffleNet from kp k+1 wavelengths in the conventional topology
Combining circuit and packet switching using a large port-count optical cross-connect for data center networks
NASA Astrophysics Data System (ADS)
Huang, Qirui; Yeo, Yong-Kee; Zhou, Luying
The exponential increase in the data center network traffic has posed new challenges for achieving high throughput, low latency and energy consumption. To address these challenges, this paper presents a novel scheme that combines optical circuit and packet switching technologies together in a single optical cross-connect for data center networks. By utilizing fast tunable linecards and parallel array waveguide grating routers, the optical cross-connect can offer low latency, large scalability and high throughput in datacenter networks. A scheduling technique is designed to simultaneously accommodate circuit switching and packet switching in the optical cross-connect. The physical performance of this optical cross-connect in circuit and packet switching modes is investigated by experiments. In addition, the network performance of the optical cross-connect is evaluated through simulations under a mixed circuit/packet-switched traffic pattern. Results show that the network performance of the optical cross-connect does not degrade significantly with an increase in the number of racks, but it is affected by the circuit-switched traffic proportion.
CROSS CONNECTIONS SChOOl Of INfORmaTION STudIES (iSChOOl)
McConnell, Terry
· Syracuse Information Systems Evaluation Project: applies the theories and research of social and information sciences to improve information security practices and information technology usageCROSS CONNECTIONS SChOOl Of INfORmaTION STudIES (iSChOOl) TheSchoolofInformation
Large nonblocking multiwavelength cross-connects based on fiber Bragg gratings for WDM networks
NASA Astrophysics Data System (ADS)
Chen, Yung Kung; Lee, Chien-Chung; Tu, Yuan-Kuang; Liaw, Shien-Kuei; Chang, Chi-Hsiung
Multi-wavelength cross-connects (WXCs) will play a key role to provide more reconfiguration flexibility and network survivability in wavelength-division-multiplexing (WDM) transport networks. In this paper, we utilize three different fiber-Bragg-grating (FBG) based P-type, S-type, and N-type building blocks with optical circulators and related control devices for constructing large rearrangeably non-blocking N X N WXCs. The P-type building block is composed of certain 'parallel' FBG-element chains placed between the control device of two large mechanical optical switches (OSWs). The S-type building block consists of a 'series' of FBG elements and the control device of 2 X 2 OSWs. The non-switched N-type building block includes a 'series' of FBG elements with appropriate stepping motor or PZT control devices. Large N X N WXC structures, with minimum number of required constitutive elements, based on a three-stage Clos network are then constructed. We investigate their relevant characteristics, compare the required constitutive elements, and estimate the dimension limits for these WXC architectures.
Parallel and simultaneous spatial mode conversion using photorefractive crystal for photonic cross-connect
NASA Astrophysics Data System (ADS)
Zhao, Yanfeng; Okamoto, Atsushi; Maeda, Tomohiro; Hirasaki, Yuki; Tomita, Akihisa; Bunsen, Masatoshi
In this paper, we present a novel technology for photonic cross-connect (PXC) in spatial mode domain for the realization of advanced and flexible optical transmission of spatial modes. The PXC is a kind of all -optical devices to switch highspeed optical signals for mode-division multiplexing (MDM) network and it is able to perform signal labeling in the spatial mode domain similar to current photonic switching in the wavelength domain. In addition, parallel and simultaneous mode conversion can be realized using multiplex holograms in a photorefractive crystal (PRC). In our experiment, during the recording process, a rewritable hologram is recorded in the PRC (LiNbO3) through the interference between the signal beam with certain input mode and the reference beam with the phase distribution of the desired output mode. Signal beams are generated by computer generated hologram (CGH) using a spatial light modulator (SLM) instead of an optical fiber emergent beam, and reference beams are generated by phase only modulation using another SLM. Subsequently, during the converting process, the input signal beam is converted into the desired output mode through the holographic diffract ion in the crystal and free-space propagation by an optical lens. By using phase code multiplexing method, parallel mode conversions can be realized. We performed an experiment on parallel mode conversions of several different conversion pairs. Signal beams and reference beams intersected in the PRC with an angle of 18.43 degree. The intensity distributions of converted modes were observed by CCD camera set on the Fourier plane. We confirmed that the two modes inter-conversion of LP11 with LP21 was successfully implemented.
A service restoration time study for distributed control SONET digital cross-connect system self-healing networks
T.-H. Wu; H. Kobrinski; D. Ghosal; T. V. Lakshman
The viability of distributed control restoration using digital cross-connect systems (DCSs) depends on its capability for restoring services within specified time requirements. A Bellcore study of the impact of the DCS architecture on distributed restoration is reported. It is concluded that currently proposed distributed control DCS self-healing schemes may not meet the two-second restoration objective, regardless of the distributed algorithm,
Some thoughts about random walks on figure eight
NASA Astrophysics Data System (ADS)
Kholodenko, Arkady L.
In this paper we discuss the issues of recurrence and transience of random walks in multiply connected spaces and, in particular, in the presence of knots. Such problems are of interest in polymer physics since almost all sufficiently long linear polymer chains are (quasi) knotted at least at theta solvent quality conditions and, hence, the transience/recurrence provides mathematically rigorous definition of the entanglement concept. These problems are also of biological interest since they clarify the role of topology in problems involving molecular recognition. Obtained results extend and generalize the results of earlier published Rapid Communication (Kholodenko, Phys. Rev. E 58 (1998) R5213). They also provide some answers to problems which were just mentioned in our earlier published report (Kholodenko, Phys. Reports 298 (1998) 251).
Fluorescence monitoring at a recycled water treatment plant and associated dual distribution system--implications for cross-connection detection.
Hambly, A C; Henderson, R K; Storey, M V; Baker, A; Stuetz, R M; Khan, S J
Dual distribution systems are becoming increasingly common in greenfield housing developments in Australia for the redistribution of recycled water to households for non-potable use. Within such schemes there exists the potential for cross-connections between recycled and drinking water systems. Due to the high level of recycled water treatment, these events are unlikely to lead to outbreaks of illness in the community. Nonetheless, they do represent a breach of the recycled water risk management strategy and therefore an elevated level of risk to consumers. Furthermore, cross-connection events have the potential to undermine public confidence in these types of water recycling. A rapid, highly sensitive method of cross-connection detection may therefore provide an additional level of confidence in these schemes. The aim of this research was to determine the potential for using fluorescence spectroscopy as a monitoring tool in water treatment plants and dual distribution systems. Samples from both the water recycling plant and dual distribution system were collected on a weekly basis over 12 weeks. Fluorescence excitation-emission matrix (EEM) spectra and water quality parameters including dissolved organic carbon, UV(254), pH, conductivity, free chlorine and turbidity were obtained for each sample. The fluorescence EEM spectra of recycled and drinking water were distinctly different and exhibited low variability throughout the course of the sampling program, indicating a degree of stability of the fluorescent components within the organic matter. A ten-fold difference in mean fluorescence intensity was observed for recycled water compared to drinking water, which was greater than the difference observed for the other measured water quality parameters. Probabilistic analysis was used to determine the reliable detection limit of recycled water contamination of drinking water. Accounting for the inherent variability of both recycled water and drinking water, a 45% contamination of recycled water in drinking water could be detected with a signal-to-noise ratio greater than 3 for more than 95% of individual random sample pairs. Greater sensitivity can be assured by averaging numerous samples. In comparison, a 70% contamination of recycled water in drinking water was required for the same detection using conductivity. PMID:20655084
Silicon Photonics III Conference, Photonics West 2008, San Jose, CA, USA Cascaded active silicon microresonator array cross-connect circuits for
Poon, Andrew Wing On
Silicon Photonics III Conference, Photonics West 2008, San Jose, CA, USA Cascaded active silicon microresonator array cross-connect circuits for WDM networks-on-chip (invited) Andrew W. Poon, Fang Xu, and Xianshu Luo Photonic Device Laboratory, Department of Electronic and Computer Engineering, The Hong Kong
Experimental evaluation of an all-optical cross-connect based on micro-electro-mechanical system switches
NASA Astrophysics Data System (ADS)
Asquini, Rita; Mancini, Rita; d'Alessandro, Antonio; Valentino, Margherita; Signorazzi, Mario; Vespasiano, Gaetano
Performances of a WDM multistage interconnection architecture have been evaluated, by using measurements carried out on a 8×8 MEMS 2-D photonic switch made by OMM Inc.. Maximum and minimum insertion losses resulted 3.96 dB and 1.42 dB respectively at the wavelength of 1540.5nm. Furthermore polarization dependent loss and crosstalk were below 0.7 dB and -79 dB respectively. A rist time of 12 ms and a fall time of 4 ms were measured. The measurements were used to study a 40 Gbit/s WDM network which operates by using two fibers each supporting 8 multiplexed channels for a total of 16 channels whose carriers are spaced by 50 GHz and modulated at 2.5 Gbit/s. The network includes an optical cross connect (OXC), designed to switch part or all of the eight channels from one fiber to the other. The heart of the OXC is a 16×16 strictly non-blocking switching matrix based on a three stage Clos architecture. Insertion losses lower than 7 dB were evaluated over the entire network and the eye diagram spreads by just about 4%.
The drinking water distribution system simulator (DSS) from the U.S. EPA was operated with a direct cross-connection of 0.3% wastewater to system volume per day for 70 d. During the cross-connection, tap water, wastewater, and system discharge water were monitored to ensure that ...
Performance analysis of dedicated protection and shared protection for waveband switching based on multi-granularity optical cross-connect
NASA Astrophysics Data System (ADS)
Guo, Lei; Wang, Xingwei; Jiang, Dingde; Hou, Weigang; Ji, Wei
In order to save the switching ports and the cost of Multi-Granularity Optical Cross-Connect (MG-OXC), the waveband switching technique was proposed to groom multiple wavelength-level traffic to a few waveband tunnels to be switched by a few switching ports in MG-OXC. At the same time, protection for fibers is very important to ensure the service continuity since each wavelength carries a lot of traffic. Although existing works have addressed the waveband switching protection, most of them separately considered only the dedicated protection or shared protection in static demand scenario and did not deeply analyze and compare the dedicated protection and shared protection in dynamic demand scenario. Therefore, in this paper, we deeply study the consumptions of wavelengths in fibers and ports in MG-OXCs for Waveband Shared Protection (WSP) and Waveband Dedicated Protection (WDP) in dynamic demand scenario, and propose the port-cost calculation and update methods based on a new waveband layered auxiliary graph that is developed based on MG-OXC structure. In simulations, we compare WSP, WDP, traditional end-to-end waveband shared protection and traditional end-to-end waveband dedicated protection. Simulation results show that the shared protection has smaller port-cost, better wavelength utilization efficiency and lower blocking probability than the dedicated protection with the same waveband switching policy, and the sub-path waveband switching has bigger port-cost, better wavelength utilization efficiency and lower blocking probability than the end-to-end waveband switching with the same backup wavelength assignment policy.
BER Performance Degradation Due to Component Crosstalk of AN Arrayed Waveguide Grating And FBG-OC Based WDM Cross-Connect
S. P. Majumder; S. Dey
In this paper we investigate the impact of intra-band incoherent crosstalk due to bi-directional WDM cross-connect (OXC) based on arrayed waveguide grating (AWG), tunable Fiber Bragg gratings (FBG) and optical circulators (OC) on the bit-error-rate (BER) performance of a WDM transmission system. This paper reveals that there is a power penalty suffered by the system due to OXC. The limiting
128×128 three-dimensional MEMS optical switch module with simultaneous optical path connection for optical cross-connect systems
NASA Astrophysics Data System (ADS)
Mizukami, Masato; Yamaguchi, Joji; Nemoto, Naru; Kawajiri, Yuko; Hirata, Hirooki; Uchiyama, Shingo; Makihara, Mitsuhiro; Sakata, Tomomi; Shimoyama, Nobuhiro; Oda, Kazuhiro
A 128×128 three-dimensional MEMS optical switch module and a switching-control algorithm for high-speed connection and optical power stabilization are described. A prototype switch module enables the simultaneous switching of all optical paths. The insertion loss is less than 4.6dB and is 2.3dB on average. The switching time is less than 38ms and is 8ms on average. We confirmed that the maximum optical power can be obtained and optical power stabilization control is possible. The results confirm that the module is suitable for practical use in optical cross-connect systems.
Effect of Correlations of Component Failures and Cross-Connections of EDGs on Seismically Induced Core Damages of a Multi-Unit Site
NASA Astrophysics Data System (ADS)
Muramatsu, Ken; Liu, Qiao; Uchiyama, Tomoaki
Aiming at proposing effective applications of seismic probabilistic safety assessment (PSA) for design and risk management of nuclear facilities, we conducted a preliminary seismic PSA study for a multi-unit site to examine core damage frequency (CDF) and core damage sequences with consideration of the effect of correlations of component failures. In addition, we also examined the effectiveness of an accident management measure, namely, cross-connections of emergency diesel generators (EDGs) between adjacent units in this study. Twin BWR-5 units of the same design were hypothesized to be located at the same site in this study and the CDF as well as the accident sequences of this two-unit site were analyzed by using SECOM2, a system reliability analysis code for seismic PSA. The results showed that the calculated CDF was dependent on the assumptions on the correlations of component failures. When the rules for assigning correlation coefficients of component responses defined in the NUREG-1150 program were adopted, the CDF of a single unit, the CDF of this two-unit site (the frequency of core damages of at least one unit at this site) and the frequency of simultaneous core damages of both units increased by factors of about 1.3, 1.2 and 2.3, respectively. In addition, it might be possible that the simultaneous core damages of both units are caused by different accident sequence pairs as well as the same sequence pairs. When cross-connections of EDGs between two units were available, the CDF of a single unit, the CDF of this two-unit site as well as the frequency of simultaneous core damages of both units decreased. In addition, the CDF of this two-unit site was smaller than the CDF of a single unit site. These results show that cross-connections of EDGs might be beneficial for a multi-unit site if the rules for assigning correlation coefficients defined in NUREG-1150 program are reasonable.
A multi-chip directly mounted 512-MEMS-mirror array module with a hermetically sealed package for large optical cross-connects
NASA Astrophysics Data System (ADS)
Mi, Xiaoyu; Soneda, Hiromitsu; Okuda, Hisao; Tsuboi, Osamu; Kouma, Norinao; Mizuno, Yoshihiro; Ueda, Satoshi; Sawaki, Ippei
This paper describes the design, fabrication and performance of a 512-MEMS-mirror array module with a hermetically sealed package for large optical cross-connects. This configuration enables a ± 5° rotation of the two-axis stationary operation under a drive voltage of 160 V, with a high resonant frequency of 2 kHz. The 512-MEMS-mirror array module was constructed using newly developed multi-chip direct mounting (MCDM) technology, which allowed us to use small scale mirror array chips and greatly simplifies the fabrication process. The MCDM technology was demonstrated to be especially well suited to building large port count mirror array modules without the size limitation involved with handling wafers. The 512-MEMS-mirror array module measures a compact 122 mm × 60 mm.
The need for rapid and inexpensive tests in toxicology has prompted several advisory panels to recommend motor activity as a screen for neurotoxicity. Since motor activity reflects the general status of the organism, disruption produced by a variety of neurotoxic and non-neurotox...
Matrix integral expansion of colored Jones polynomials for figure-eight knot
Alexander Alexandrov; Dmitry Melnikov
In this note we examine a possible extension of the matrix integral representation of knot invariants beyond the class of torus knots. In particular, we study a representation of the SU(2) quantum Racah coefficients by double matrix integrals. We find that the Racah coefficients are mapped to expansion coefficients in some basis of double integrals. The transformed coefficients have a number of interesting algebraic properties.
McConnell, Terry
-- offers students an opportunity to address the health care and legal needs of disadvantaged children at the intersection of law, politics, and the media. >> The Low Income Taxpayer Clinic offers student attorneys regarding income tax matters. >> The Securities Arbitration and Consumer Law Clinic provides legal
Simulation Study to Improve Focalization of a Figure Eight Coil by Using a Conductive Shield Plate and a Ferromagnetic Block.
Zhao, Chen; Zhang, Shunqi; Liu, Zhipeng; Yin, Tao
A new method to improve the focalization and efficiency of the Figure of Eight (FOE) coil in rTMS is discussed in this paper. In order to decrease the half width of the distribution curve (HWDC), as well to increase the ratio of positive peak value to negative peak value (RPN) of the induced electric field, a shield plate with a window and a ferromagnetic block are assumed to enhance the positive peak value of the induced electrical field. The shield is made of highly conductive copper, and the block is made of highly permeable soft magnetic ferrite. A computer simulation is conducted on ANSYS® software to conduct the finite element analysis (FEA). Two comparing coefficients were set up to optimize the sizes of the shield window and the block. Simulation results show that a shield with a 60 mm × 30 mm sized window, together with a block 40 mm thick, can decrease the focal area of a FOE coil by 46.7%, while increasing the RPN by 135.9%. The block enhances the peak value of the electrical field induced by a shield-FOE by 8.4%. A real human head model was occupied in this paper to further verify our method. PMID:25594972
Integrated null-flux suspension and multiphase propulsion system for magnetically-levitated vehicles
Rote, D.M.; He, Jianliang; Johnson, L.R.
This report discusses a propulsion and stabilization system comprising a series of figure 8 coils mounted vertically on the walls of the guideway to provide suspension, lateral guidance and propulsion of a magnetically levitated vehicle. This system further allows for altering the magnetic field effects by changing the relative position of the loops comprising the figure 8 coils either longitudinally and/or vertically with resulting changes in the propulsion, the vertical stability, and the suspension.
CANR | Cooperative Extension | REC | UD Home | UD Directory | UD Daily | Find It (A-Z) | BUDDY | Room Schedules | Figure Eight Thu, Dec-06-07 Fall Faculty
Sparks, Donald L.
Breakfast Minutes from Spring Faculty Mtg. Important Tips Holiday Rituals Promote Family Ties Talking Turkey & Links > UD Human Resources > Submit CANR Feature > Submit Site Suggestions > CANR Events & Important's new Recycle Page! CANR Spotlight: New CANR Graduate Fellowship Awarded to Jennifer Seiter Jennifer
A silicon-cast device that aids in securing rope ends by ensuring a figure-eight knot is tied for use in gym and rock climbing
Treadway, Shane M
Between the years of 1953 and 2005, there were 253 fatalities from rappel failure/error. Some of these deaths may have been prevented if a stopper knot was tied at the end of the rope. Current climbing habits do not reinforce ...
The present report describes the effects of prenatal administration exposure of a large number of compounds on the locomotor activity levels of mice. The effects of these treatments on the postnatal growth, viability, morphology and reproductive function from the first experiment...
Computation of magnetic suspension of maglev systems using dynamic circuit theory
He, J.L.; Rote, D.M.; Coffey, H.T.
Dynamic circuit theory is applied to several magnetic suspensions associated with maglev systems. These suspension systems are the loop-shaped coil guideway, the figure-eight-shaped null-flux coil guideway, and the continuous sheet guideway. Mathematical models, which can be used for the development of computer codes, are provided for each of these suspension systems. The differences and similarities of the models in using dynamic circuit theory are discussed in the paper. The paper emphasizes the transient and dynamic analysis and computer simulation of maglev systems. In general, the method discussed here can be applied to many electrodynamic suspension system design concepts. It is also suited for the computation of the performance of maglev propulsion systems. Numerical examples are presented in the paper. 15 refs., 7 figs., 1 tab.
Computation of magnetic suspension of maglev systems using dynamic circuit theory
NASA Technical Reports Server (NTRS)
He, J. L.; Rote, D. M.; Coffey, H. T.
Dynamic circuit theory is applied to several magnetic suspensions associated with maglev systems. These suspension systems are the loop-shaped coil guideway, the figure-eight-shaped null-flux coil guideway, and the continuous sheet guideway. Mathematical models, which can be used for the development of computer codes, are provided for each of these suspension systems. The differences and similarities of the models in using dynamic circuit theory are discussed in the paper. The paper emphasizes the transient and dynamic analysis and computer simulation of maglev systems. In general, the method discussed here can be applied to many electrodynamic suspension system design concepts. It is also suited for the computation of the performance of maglev propulsion systems. Numerical examples are presented in the paper.
Switch element reliability required to maintain large-scale photonic cross-connect switch reliability
K. Noguchi; M. Koga
This paper discusses how switch element reliability affects the reliability of large-scale switches. We evaluated the relation between switch element FIT and large-scale OXC reliability. In so doing, we found that the DC-SW is the most reliable type of optical switch because it can be composed of fewer switch elements.
TU41-(15)-3 350x350 MODULAR OPTICAL CROSS-CONNECT WITH
Bergman, Keren
in vertical slots inside a card cage. An attached optical chassis with four folding mirrors direct light from. A fully populated system would ideally yield a 384 (16x24) by 384 non-blocking switch. The gold-coated
Under the current regulations (CFR 503), Class B biosolids may be land applied with certain site restrictions. One method for achieving Class B status is to raise the pH of the sludge to >12 for a minimum of 2 hours with an alkaline material (normally lime). Alternately, a Clas...
77 FR 29618 - The Release of the Draft Environmental Impact Statement and the Announcement of a Public Hearing...
Federal Register 2010, 2011, 2012, 2013, 2014
...a Public Hearing for the Figure Eight Island Inlet and Shoreline Management Project, on Figure Eight Island, New Hanover County, NC AGENCY: Department...and northern sections of Figure Eight Island. The terminal groin structure will...
47 CFR 69.121 - Connection charges for expanded interconnection.
Code of Federal Regulations, 2010 CFR
...subelements shall be used. (1) A cross-connect subelement shall be established for charges associated with the cross-connect cable and associated facilities...services. Charges for the cross-connect subelement shall not be...
Design of NSLS-II High Order Multipole Correctors
Rehak,M.; Danby, G.; Bengtsson, Jo; Jackson, J.; Skaritka, J.; Spataro, C.
Feasibility studies for two families of corrector magnets for NSLS-II are presented. The first family of magnets are generalizations of figure eight quadrupoles using rotationally symmetric breaks in the return yoke to fit in available space. Properties specific to figure eight magnet are identified. The second type of magnet is a combined sextupole/dipole trim.
Adult male Long-Evans rats were intubated with either 0,5,6, or 7 mg/kg trimethyltin chloride. Activity was measured for 1 hr in a figure-eight maze 2 hr after dosing (day 0) and again on days 4,8,16 and 32 after dosing. On days 49-51, activity was measured in a figure-eight maze...
Choreographic solution to the general relativistic three-body problem
Tatsunori Imai; Takamasa Chiba; Hideki Asada
We revisit the three-body problem in the framework of general relativity. The Newtonian N-body problem admits choreographic solutions, where a solution is called choreographic if every massive particles move periodically in a single closed orbit. One is a stable figure-eight orbit for a three-body system, which was found first by Moore (1993) and re-discovered with its existence proof by Chenciner and Montgomery (2000). In general relativity, however, the periastron shift prohibits a binary system from orbiting in a single closed curve. Therefore, it is unclear whether general relativistic effects admit a choreographic solution such as the figure eight. We carefully examine general relativistic corrections to initial conditions so that an orbit for a three-body system can be closed and a figure eight. This solution is still choreographic. This illustration suggests that the general relativistic N-body problem also may admit a certain class of choreographic solutions.
"Some Unpublished Studies by Paul Rehak on Gender in Aegean Art," edited by John Younger
Rehak, Paul
. MM III faience figurines from the South Propylon of Knossos show women in a "lactans" pose (holding their breasts) and wearing necklaces of beads in the shape of figure-eight shields. 13 The plaster plaque from Mycenae (Pl. Id) 14 shows a woman... wearing a figure-eight shield, in much the same posture (note the feet) as a female figure on a sealstone 15 and as the little floating figure on the Mycenae Treasure ring. 16 And, to go a bit further, the shield with suspension strap occurs...
Experimental control of the spheromak tilting instability
Munson, C.; Janos, A.; Wysocki, F.; Yamada, M.
The magnetohydrodynamic (MHD) tilting instability of the spheromak configuration has been experimentally investigated by recording the time evolution of the magnetic field configuration with small magnetic probes. Passive coil systems such as the figure eight and saddle coils have been proven experimentally to be effective against this instability.
JOURNAL OF LIGHTWAVE TECHNOLOGY, VOL. 31, NO. 11, JUNE 1, 2013 1809 Amplified 2-Thulium-Doped All-Fiber
Byer, Robert L.
JOURNAL OF LIGHTWAVE TECHNOLOGY, VOL. 31, NO. 11, JUNE 1, 2013 1809 Amplified 2- Thulium-Doped All. Byer Abstract--We report the first mode-locked, thulium-doped fiber figure-eight laser. The mode. INTRODUCTION THULIUM-DOPED lasers have a wide gain spectrum ranging from 1.8 to 2.1 , depending on the host
Triadimefon is a widely used systemic fungicide, yet there is little published information on its effects in mammals. This study describes the effects of triadimefon in male and female rats using a functional observational battery (FOB), motor activity (measured in a figure-eight...
The behavioral effects of 3,3'-iminodipropionitrile (IDPN) were studied using reflex modification of the acoustic startle response and figure-eight maze activity. umber of experiments were conducted with separate groups of adult male Long Evans hooded rats exposed to saline, or 5...
Proprioception in Individuals with ACL-Deficient Knee and Good Muscular and Functional Performance
Sergio T. Fonseca; Juliana M. Ocarino; Paula L. P. Silva; Raquel B. Guimarăes; Marcela C. T. Oliveira; Cristiane A. Lage
The objective of this study was to verify whether proprioception is affected in individuals with ACL-deficient knees and good functional and muscular performances. Eleven subjects with ACL injury and 11 controls participated in the study. Functional performance was assessed using the Cincinnati Knee Rating System (CKRS), hop index, and figure-eight ratio. An isokinetic test was done to evaluate muscular performance.
CCAMP WG V. Sahay B. Narayanan
Jain, Raj
Networks July 2001 Network Transport Interface Protocol (NTIP) for Photonic Cross Connects (PXC) Status interface protocol (NTIP) for photonic cross connects (PXC). NTIP is implemented between a PXC and transport between directly attached PXC and TNE. The use of TCP as the transport protocol ensures reliable and in
Contribution Number: OIF2001.208 Working Group: Signaling, Architecture
Jain, Raj
Interface Protocol (NTIP) for Photonic Cross Connect (PXC). SOURCE: Vasant Sahay Rajiv Ramaswami Osama Aboul) for photonic cross connects (PXC). NTIP is implemented between a PXC and transport network element (TNEs). NTIP as the transport protocol ensures reliable and in-sequence delivery of NTIP messages. Notice: This contribution has
IEEE Communications Magazine April 2003 1050163-6804/03/$17.00 2003 IEEE TOPICS IN LIGHTWAVE
Cao, Xiaojun (Matt)
.g., number of ports) of photonic (both optical and electronic) cross-connects, as well as the cost the remarkable techno- logical advances in building photonic cross-connect systems and associated switch fab- rics, the high cost (both capital and operating expenditures) and unproven reliability of huge switches
Sediment concentration versus water discharge during single hydrologic events in rivers
Williams, G.P.
Relations between sediment concentration (C) and water discharge (Q) for a hydrologic event, such as a flood, are studied qualitatively by analyzing "smoothed" temporal graphs (discharge and concentration vs. time) in terms of mode, spread, and skewness. Comparing C Q ratios at a given discharge on the rising and falling limbs of the discharge hydrograph provides a consistent, reliable method for categorizing C-Q relations. Five common classes of such relations are single-valued (straight or curved), clockwise loop, counterclockwise loop, single-valued plus a loop, and figure eight. Temporal-graph mode and skewness influence the type of relation, whereas temporal-graph spread affects the details of the particular C-Q relation (its graphical breadth, shape, orientation, and plotted location). Field examples of the various types of relations are given, including varieties that heretofore have received little attention, such as the figure eight. Explanations for each type of C-Q relation are discussed. ?? 1989.
NSDL National Science Digital Library
Bob Urschel
This website gives both a mathematical and logical explanation of the analemma, which is seen on many maps and globes, and is a record of the path the sun takes through the sky during the course of a year. This figure-eight pattern is due to the Earth's elliptical orbit and its tilted axis. Using animations, equations, and diagrams, the author explains in detail what the analemma is and what causes it to happen.
Three-dimensional drawings in isometric conditions: relation between geometry and kinematics
Joe T. Massey; Joseph T. Lurito; Giuseppe Pellizzer; Apostolos P. Georgopoulos
Normal human subjects grasped a 3-D isometric handle with an otherwise unrestrained, pronated hand and exerted forces continuously to draw circles, ellipses and lemniscates (figure-eights) in specified planes in the presence or absence of a 3-D visual force-feedback cursor and a visual template. Under any of these conditions and in all subjects, a significant positive correlation was observed between the
Development of a high-Performance MALDI-TOF mass spectrometer utilizing a spiral ion trajectory
Takaya Satoh; Takafumi Sato; Jun Tamura
A novel MALDI-TOF mass spectrometer that utilizes a spiral ion trajectory was developed. In this mass spectrometer, the ions\\u000a sequentially passed through four toroidal electrostatic sectors and revolved along a figure-eight-shaped orbit on a particular\\u000a projection plane. Each toroidal electrostatic sector had eight stories, and during multiple revolutions, the ion trajectory\\u000a shifted perpendicular to the projection plane in every cycle,
Three-body problem periodic orbits with vanishing angular momentum
NASA Astrophysics Data System (ADS)
Titov, V.
Periodic solutions of the general three-body problem are investigated in the shape space. Two different solutions are considered: the first is an extension of the well-known figure-eight orbit, and the second one is from the free-fall problem. Using the shape space, we reduce the dimension of the problem. These orbits are obtained numerically and described on the Euclidean plane and on the shape sphere.
46 CFR 78.17-5 - Valves and closing appliances.
Code of Federal Regulations, 2014 CFR
...cross connecting valves where fitted, and other appliances such as port lights, closing mechanism of scuppers, ash chutes, and rubbish chutes, the closing of which is necessary to make a compartment watertight, are operated at least once in every...
46 CFR 78.17-5 - Valves and closing appliances.
Code of Federal Regulations, 2013 CFR
...cross connecting valves where fitted, and other appliances such as port lights, closing mechanism of scuppers, ash chutes, and rubbish chutes, the closing of which is necessary to make a compartment watertight, are operated at least once in every...
46 CFR 130.130 - Steering on OSVs of less than 100 gross tons.
Code of Federal Regulations, 2010 CFR
... (j) Each vessel with duplicate (parallel but cross-connected) power systems... (1) Control of the subordinate parallel system is located at the steering-control...main steering gear when the subordinate parallel system is not in operation;...
46 CFR 130.130 - Steering on OSVs of less than 100 gross tons.
Code of Federal Regulations, 2013 CFR
... (j) Each vessel with duplicate (parallel but cross-connected) power systems... (1) Control of the subordinate parallel system is located at the steering-control...main steering gear when the subordinate parallel system is not in operation;...
46 CFR 130.130 - Steering on OSVs of less than 100 gross tons.
Code of Federal Regulations, 2011 CFR
... (j) Each vessel with duplicate (parallel but cross-connected) power systems... (1) Control of the subordinate parallel system is located at the steering-control...main steering gear when the subordinate parallel system is not in operation;...
46 CFR 130.130 - Steering on OSVs of less than 100 gross tons.
Code of Federal Regulations, 2014 CFR
... (j) Each vessel with duplicate (parallel but cross-connected) power systems... (1) Control of the subordinate parallel system is located at the steering-control...main steering gear when the subordinate parallel system is not in operation;...
46 CFR 130.130 - Steering on OSVs of less than 100 gross tons.
Code of Federal Regulations, 2012 CFR
... (j) Each vessel with duplicate (parallel but cross-connected) power systems... (1) Control of the subordinate parallel system is located at the steering-control...main steering gear when the subordinate parallel system is not in operation;...
In-line and cross-flow multi-frequency vortex-induced vibrations of a long flexible cylinder are phase-locked under wake-body synchronization
NASA Astrophysics Data System (ADS)
Bourguet, Remi; Karniadakis, George; Triantafyllou, Michael
A slender flexible body with bluff cross-section immersed in cross-flow exhibits vortex-induced vibrations. The vibrations are excited by the flow under a condition of lock-in defined as the synchronization between vortex formation and body displacement. Within a sheared current, the possible occurrence of the lock-in condition at a number of different locations can lead to broadband vibrations involving a wide range of excited frequencies and structural wavenumbers. In a previous study focusing on the vortex-induced vibrations of a flexible cylinder at a single frequency in each direction, we have found that the lock-in condition is established through counter-clockwise figure-eight trajectories where the body moves upstream at the extremes of the cross-flow oscillation. In the present work, on the basis of direct numerical simulation results, we show that this mechanism can be generalized to multi-frequency responses: even if the trajectory shape substantially departs from a figure eight, the phase difference between the components of the in-line and cross-flow vibrations locally involved in the lock-in phenomenon remains within a particular range, associated with counter-clockwise figure-eight orbits in the mono-frequency case.
Physiological modules for generating discrete and rhythmic movements: component analysis of EMG signals
Bengoetxea, Ana; Leurs, Françoise; Hoellinger, Thomas; Cebolla, Ana Maria; Dan, Bernard; Cheron, Guy; McIntyre, Joseph
A central question in Neuroscience is that of how the nervous system generates the spatiotemporal commands needed to realize complex gestures, such as handwriting. A key postulate is that the central nervous system (CNS) builds up complex movements from a set of simpler motor primitives or control modules. In this study we examined the control modules underlying the generation of muscle activations when performing different types of movement: discrete, point-to-point movements in eight different directions and continuous figure-eight movements in both the normal, upright orientation and rotated 90°. To test for the effects of biomechanical constraints, movements were performed in the frontal-parallel or sagittal planes, corresponding to two different nominal flexion/abduction postures of the shoulder. In all cases we measured limb kinematics and surface electromyographic activity (EMG) signals for seven different muscles acting around the shoulder. We first performed principal component analysis (PCA) of the EMG signals on a movement-by-movement basis. We found a surprisingly consistent pattern of muscle groupings across movement types and movement planes, although we could detect systematic differences between the PCs derived from movements performed in each shoulder posture and between the principal components associated with the different orientations of the figure. Unexpectedly we found no systematic differences between the figure eights and the point-to-point movements. The first three principal components could be associated with a general co-contraction of all seven muscles plus two patterns of reciprocal activation. From these results, we surmise that both "discrete-rhythmic movements" such as the figure eight, and discrete point-to-point movement may be constructed from three different fundamental modules, one regulating the impedance of the limb over the time span of the movement and two others operating to generate movement, one aligned with the vertical and the other aligned with the horizontal. PMID:25620928
Fourier transformed picosecond synchronously pumped optical parametric oscillator without spectral filtering element
NASA Astrophysics Data System (ADS)
Ryasnyanskiy, A.; Dubreuil, N.; Delaye, Ph.; Frey, R.; Roosen, G.
We experimentally demonstrated a wavelength-tunable passively mode-locked Erbium-doped figure-eight fiber laser. Wide tunability is achieved using a high-birefringence (hi-bi) fiber Sagnac loop. The filter transmission function is controlled by selecting the hi-bi fiber loop length. The output pulses are wavelength tunable over a range from 1525 nm to 1555 nm. The FWHM of the autocorrelation trace is about 3.1 ps and the pulse spectrum has a FWHM of 1.5 nm. The pulse temporal and spectral widths remain constant over the tunable range.
NSDL National Science Digital Library
Kahl, Jon
This site by Jon Kahl of the University of Wisconsin-Milwaukee provides an explanation of the popular photograph of the sun making an analemma (figure eight shape) taken by Dennis di Cicco. For the image shown, the sun's position in the sky was filmed at exactly the same time of day on 44 days throughout the course of one year to form an analemma. A clear explanation of how the analemma figure results and of how it can be used as a miniature almanac is also included.
Wake-body Resonance of Long Flexible Structures is Dominated by Counterclockwise Orbits
NASA Astrophysics Data System (ADS)
Bourguet, Rémi; Modarres-Sadeghi, Yahya; Karniadakis, George E.; Triantafyllou, Michael S.
We identify a dominant mechanism in the interaction between a slender flexible structure undergoing free vibrations in sheared cross-flow and the vortices forming in its wake: energy is transferred from the fluid to the body under a resonance condition, defined as wake-body frequency synchronization close to a natural frequency of the structure; this condition occurs within a well-defined region of the span, which is dominated by counterclockwise, figure-eight orbits. Clockwise orbits are associated with damping fluid forces.
Colored Kauffman homology and super-A-polynomials
NASA Astrophysics Data System (ADS)
Nawata, Satoshi; Ramadevi, P.; Zodinmawia
We study the structural properties of colored Kauffman homologies of knots. Quadruple-gradings play an essential role in revealing the differential structure of colored Kauffman homology. Using the differential structure, the Kauffman homologies carrying the symmetric tensor products of the vector representation for the trefoil and the figure-eight are determined. In addition, making use of relations from representation theory, we also obtain the HOMFLY homologies colored by rectangular Young tableaux with two rows for these knots. Furthermore, the notion of super- A-polynomials is extended in order to encompass two-parameter deformations of PSL(2, ?) character varieties.
Joining gut ends of unequal diameter.
Barnes, J P; Greer, C R; Sasso, R D
A simple, safe and precise method for joining ends of unequal diameter is presented. Very little septum is created by either anterior or posterior rows. The figure-eight seems to crush the septum almost flat on the posterior row and the Halsted's create an absolutely minimal septum anteriorly where they are correctly placed. The posterior row used two layers of submucosa and the anterior one, four layers, and no reliance is placed on the serosa-muscularis layer. This technique is thought to have distinct advantages relative to strength, safety, and minimal septum formation. Images Fig. 1 Figure 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 PMID:1190867
Futurist sculpting: modeling movement in 3D
Krawczyk, Piotr
, which was displayed as a part of SIGGRAPH 2003 art gallery. Recently, in his thesis Real-time Geometric Motion Blur [11], Nathaniel Jones ap- plied certain ideas of motion swept volumes to create a motion shell behind a moving object. The effect created... of this thesis are included five movie files, in Quicktime format. Below is a list and some information about them. animation stretch2.mov This is a video file of Motion Elasticity applied to simple animated sphere moving in a figure eight. In this case Motion...
[Anterior transolecranon fracture-dislocations of the elbow in children: A case report and review of the literature].
Tiemdjo, H; Kinkpe, C; Coulibaly, N F; Sane, A; Ndiaye, A; Seye, S I L
Anterior transolecranon fracture-dislocations of the elbow are rare in children and the literature is poor in recommendations for the management of these lesions. We report a new case with a type of lesion that has not been described previously and discuss this pathology. Based on a literature review, we propose a classification into four types of anterior transolecranon fracture-dislocations of the elbow in children, thereby guiding surgical indications. We recommend reduction and synthesis using a figure-eight tension-band wire in avulsions and transverse type I and II fractures. The bone plate is the best indication in type III oblique fractures in older children. PMID:26047739
The Construction of Gender in Late Bronze Age Aegean Art. A Prolegomenon
Rehak, Paul
, suggestrng that women actually performed the jump Qmmerwahr 1990:202 Tryns No. 1). White-skinned fresco figures wearing a piece of masculine armour. the boars' tusk helmet. have been found at Mycenae (lmmerwahr 1990:192 Mycenae No. 1) and at Thebes Qmmerwafr...V, by author of status. but not necessarily one resfricted to men. Ai- though i have argued in tbe past that the u'hite figure wearing a figure-eight shield on a painted plaque llom the Mycenae Cuh Centre represents a 'Wamor Goddess. not all such women need...
Continuation of periodic orbits in symmetric Hamiltonian and conservative systems
NASA Astrophysics Data System (ADS)
Galan-Vioque, J.; Almaraz, F. J. M.; Macías, E. F.
We present and review results on the continuation and bifurcation of periodic solutions in conservative, reversible and Hamiltonian systems in the presence of symmetries. In particular we show how two-point boundary value problem continuation software can be used to compute families of periodic solutions of symmetric Hamiltonian systems. The technique is introduced with a very simple model example (the mathematical pendulum), justified with a theoretical continuation result and then applied to two non trivial examples: the non integrable spring pendulum and the continuation of the figure eight solution of the three body problem.
A General Method for Deriving Vector Potentials Produced by Knotted Solenoids
V. V. Sreedhar
A general method for deriving exact expressions for vector potentials produced by arbitrarily knotted solenoids is presented. It consists of using simple physics ideas from magnetostatics to evaluate the magnetic field in a surrogate problem. The latter is obtained by modelling the knot with wire segments carrying steady currents on a cubical lattice. The expressions for a 31 (trefoil) and a 41 (figure-eight) knot are explicitly worked out. The results are of some importance in the study of the Aharonov-Bohm effect generalised to a situation in which charged particles moving through force-free regions are scattered by fluxes confined to the interior of knotted impenetrable tubes.
The relationship of bicycle manoeuvrability to handlebar configuration.
Mortimer, R G; Domas, P A; Dewar, R E
Since the handling characteristics of bicycles can affect their safety, the present experiment evaluated the manoevrability of three bicycles which differed only by handlebar configurations: racing (Maes Bend), standard, and high rise. The manoeuvrability of each bicycle was measured as subjects performed six tasks: circle, lane change, figure-eight, straight lane tracking, cornering, and slalom. Subjects were matched by riding experience and grouped by their familiarity with either race or standard bicycle. Analysis of variance showed that no bicycle times bicycle-familiarity interaction effects were significant in any one of the analyses. The performance observed on the bicycles with high-rise and standard handlebar configurations indicated they were not significantly different from each other. On the circle, figure-eight, and slalom tasks, performance with both the high-rise and standard handlebars was significantly better than with the race handlebars. The high-rise showed a slight performance edge on tasks requiring the greatest amount of manoeuvrability, while the standard handlebars offered more control at slower speeds and on tasks requiring stability in tracking. PMID:15677217
Stormwater samples collected from storm sewers draining small municipal separate storm sewer systems shown to be free of cross connections within an urban watershed dominated by a single land use were analyzed for pathogens (Pseudomonas aeruginosa and Staphylococcus aureus) and i...
James Clerk Maxwell Prize for Plasma Physics: The Physics of Magnetic Reconnection and Associated Particle Acceleration
James Drake
Solar and stellar flares, substorms in the Earth's magnetosphere, and disruptions in laboratory fusion experiments are driven by the explosive release of magnetic energy through the process of magnetic reconnection. During reconnection oppositely directed magnetic fields break and cross-connect. The resulting magnetic slingshots convert magnetic energy into high velocity flows, thermal energy and energetic particles. A major scientific challenge has
Integrated Placement and Skew Optimization for Rotary Clocking
Hu, Jiang
issues. Ro- tary clocking is a novel technique which employs untermi- nated rings formed by differential clocking requires latch locations to match pre-designed clock skew on rotary clock rings. This require] is a promising approach. The basic component of a rotary clock is a pair of cross-connected differential trans
Fully provisioned 112×112 micro-mechanical optical crossconnect with 35.8 Tb\\/s demonstrated capacity
D. T. Neilson; V. A. Aksyuk; S. Arney; N. R. Basavanhally; K. S. Bhalla; D. J. Bishop; B. A. Boie; C. A. Bolle; J. V. Gates; A. M. Gottlieb; J. P. Hickey; N. A. Jackman; P. R. Kolodner; S. K. Korotky; B. Mikkelsen; F. Pardo; G. Raybon; R. Ruel; R. E. Scotti; T. W. van Blarcum; L. Zhang; C. R. Giles
A scalable, fully provisioned 112×112 micro-mechanical optical cross connect with mean insertion loss of 7.5 dB@1550 nm into single-mode optical fiber and <10 ms switching speed is presented. 35.8 Tbit\\/s aggregate capacity was demonstrated with 320 Gbit\\/s TDM signals signals
Waveband grooming and IP aggregation in optical networks
Rajendran Parthiban; Rodney S. Tucker; Chris Leckie
An automatically switched optical network (ASON) can be used as the transport layer of generalized multiprotocol label switching (GMPLS) networks. The design of an ASON involves determining the number of optical cross-connects (OXC) in the network, the required number of ports per OXC, and the interconnection topology of the OXCs. Given the number of ports per OXC, we present a
An in-depth cross-layer experimental study of transport protocols over circuits
Veeraraghavan, Malathi
of dedicated- bandwidth end-to-end circuits between computers. The end-to- end circuits consist of Ethernet switches; instead they are hybrid nodes that include Ethernet interfaces that allow for the connection of host Ethernet NICs. While as with ordinary circuit switches, cross-connections have to be provisioned
Temperature Compensated Air/Fuel Ratio Control on a Recuperated Furnace
Ferri, J. L.
When recuperation is added to a furnace, air/ fuel ratio control seemingly becomes more complicated. Two methods normally used are mass flow control where the fuel pressure or flow is proportional to the mass flow of air or cross-connected control...
PXC protection switching triggered by performance monitoring with FEC for submarine cable networks
T. Otani; M. Hayashi; S. Yamamoto; M. Suzuki; N. Toda; K. Raychaudhuri
We have successfully demonstrated the protection-switching operation of photonic cross connect (PXC) triggered by the performance degradation threshold of the bit error ratio monitored with FEC in S-LTE for optical submarine cable networks. We confirmed that once the monitored errors exceed the threshold of the submarine line terminal equipment this immediately generates the loss of signal to initiate PXCs to
Dynamic Wavelength Routing in WDM Networks under Multiple Signal Quality Constraints
Tang, Jian "Neil"
--Most research works in routing and design of optical networks assume that the optical medium can carry signals without any bit error. However, the physical impairments on the optical signal quality introduced by optical components, such as erbium-doped fiber amplifiers (EDFA) and optical cross connects (OXCs), must
A Survey of Advance Reservation Routing and Wavelength Assignment in Wavelength-Routed
Vokkarane, Vinod M.
data. This allows each fiber to provide data trans- mission rates of terabits per second. An optical WDM network consists of fibers connected by switches, or optical cross connects (OXCs). In order to establish them. In a single-hop, or all-optical, WDM system, the signal is transmitted all-optically through
Traffic-partitioning approaches to grooming ring access networks
Dutta, Rudra
. We present numerical results validating the performance of the algorithms. © 2005 Optical Society- duced optical fiber communication at the lowest level of the planetary network hierarchy. The current channels by optical cross connects (OXCs) creates lightpaths that span multiple fiber links. The set
The Advent of WDM and the All-Optical Network: A Reality Check.
ERIC Educational Resources Information Center
Lutkowitz, Mark
Discussion of the telecommunications industry focuses on WDM (wavelength division multiplexing) as a solution for dealing with capacity constraints. Highlights include fiber optic technology; cross-connecting and switching wavelengths; SONET (Synchronous Optical Network) and wavelength networking; and optical TDM (Time Division Multiplexing). (LRW)
46 CFR 56.20-15 - Valves employing resilient material.
Code of Federal Regulations, 2013 CFR
...material must be fire resistant. Piping subject to internal head...locations: (i) Valves at vital piping system manifolds; (ii...cross-connects between two piping systems, at least one of which is a vital system, where failure of the valve in a fire...
46 CFR 56.20-15 - Valves employing resilient material.
Code of Federal Regulations, 2011 CFR
...material must be fire resistant. Piping subject to internal head...locations: (i) Valves at vital piping system manifolds; (ii...cross-connects between two piping systems, at least one of which is a vital system, where failure of the valve in a fire...
46 CFR 56.20-15 - Valves employing resilient material.
Code of Federal Regulations, 2014 CFR
...material must be fire resistant. Piping subject to internal head...locations: (i) Valves at vital piping system manifolds; (ii...cross-connects between two piping systems, at least one of which is a vital system, where failure of the valve in a fire...
46 CFR 56.20-15 - Valves employing resilient material.
Code of Federal Regulations, 2010 CFR
...material must be fire resistant. Piping subject to internal head...locations: (i) Valves at vital piping system manifolds; (ii...cross-connects between two piping systems, at least one of which is a vital system, where failure of the valve in a fire...
46 CFR 78.17-5 - Valves and closing appliances.
Code of Federal Regulations, 2012 CFR
...2012-10-01 2012-10-01 false Valves and closing appliances. 78.17-5...Drills, and Inspections § 78.17-5 Valves and closing appliances. (a) It shall be the duty of the master to see that all valves, including cross connecting...
Jain, Raj
) or Virtual Backplane Interface (VBI). Key words: PXC, DWDM, LMP, OLI, VBI, Fault monitoring and Fault PXC LMP to upstream PXC LMP to downstream PXC Legend: A- Fault or degradation due to path (Optical PXC Photonic Cross Connect OLI Optical Link Interface LMP Link Management Protocol W West, E
Micro-opto-electro-mechanical systems: recent developments and LETI's activities
Eric Ollier; Patrick L. Mottier
The spectacular growth in MOEMS interest is highlighted by the involvement of R&D centres and industrial companies. A lot of application fields offer large opportunities for Micro-Opto-Electro- Mechanical Systems (MOEMS): optical communications (switches, cross- connect matrix, DWDM systems ...), digital image processing, adaptive optics... but also industrial maintenance, environment, medicine,... After general ideas on MEMS and MOEMS, this paper presents
Analysis of Supportable Rates in Symmetric Blocking Wavelength Routers
Koksal, Can Emre
Analysis of Supportable Rates in Symmetric Blocking Wavelength Routers Can Emre Koksal EPFL School-- Constructing an n × n non-blocking wavelength router using n × n optical cross-connects may be impractical due requirements can be handled without a non-blocking router. In this paper, we study blocking wavelength routers
Coldren, Larry A.
.5300) Photonic integrated circuits; (060.2330) Fiber optics communications 1. Introduction Tunable lasers to dynamic wavelength provisioning in re-configurable optical add/drop multiplexers, photonic cross- connects, simplicity for integration with other components [4-6], and high reliability [7]. In this paper we report
http://www.tns.lcs.mit.edu/.../VI/VI.html Microsoft Internet Explorer Page 1 of 27 6/21/96 2:13:51 PM
Lampson, Butler W.
hypothesize that the second, and more sweeping, wave of the digital revolution will emanate from of the digital paradigm. The digital representation and transmission of information enables competition withincontrolled digital switches and crossconnect facilities. Competition has, in turn, accelerated the development
http://www.tns.lcs.mit.edu/.../VI/VI.html -Microsoft Internet Explorer Page 1 of 27 6/21/96 2:13:51 PM
Lampson, Butler W.
hypothesize that the second, and more sweeping, wave of the digital revolution will emanate from of the digital paradigm. The digital representation and transmission of information enables competition within-controlled digital switches and cross-connect facilities. Competition has, in turn, accelerated the development
112 Home Power #72 August / September 1999 Code Corner
Johnson, Eric E.
protection. The utilities always rely on extensive electronic ground-fault detectors in their ungrounded DC, and to prevent excessive voltages due to surges from lightning or unintentional cross connections with higher they are prone to picking up induced surges from nearby lightning strikes. Utility-interactive inverters are also
Performance management issues of currently operated ATM enterprise networks
Rudolf Jaeger
The author proposes a solution for the allocation and balancing of resources to maximize available bandwidth shared among corporate users. Currently established broadband virtual private networks (BVPNs) based on asynchronous transfer mode (ATM) technology comprise ATM cross-connects (ATM-CCs) and a lot of intelligent customer premises equipment (CPE). The CPE, an intelligent ATM service switcher or ATM multiplexer, enables the corporate
A decomposition approach to assign spare channels in self-healing networks
Meir Herzberg
Intelligent transmission network elements such as digital cross connect systems and add\\/drop multiplexers enable network restoration by dynamic reconfiguration of the network during failure events. Fast line and path restoration is possible by pre-assigning spare capacity to network links. The paper suggests a decomposition approach for the task of finding an economic placement of spare channels in trunk networks to
Solving the WDM network operation problem using dynamic synchronous parallel simulated annealing
Asheq Khan; Dale R. Thompson
Several variations of synchronous parallel simulated annealing (PSA) were applied to solve the static lightpath establishment wavelength selective cross-connect network operation problem for a WDM network. The goal was to find high-quality solutions to determine the efficiency of the dynamic routing and wavelength assignment algorithms. Multiple parallel processes ran the simulated annealing algorithm and exchanged solutions among them. A proposed
Passively mode-locked fiber laser with kilohertz magnitude repetition rate and tunable pulse width
NASA Astrophysics Data System (ADS)
Ai, Fei; Cao, Zhigang; Zhang, Xifen; Zhang, Chengmei; Zhang, Bo; Yu, Benli
We propose and demonstrate a strictly all-fiber, erbium doped passively mode-locked figure-eight fiber laser (EDFL). In the laser structure, we use the nonlinear optical loop mirror combination with a variable ratio coupler (VRC-NOLM) to achieve mode-locking. Due to the nonlinear effect in the nonlinear fiber, stable self-starting pulse is obtained. In order to reduce the repetition of pulse, a segment of nonlinear fiber (NLF) has been incorporated into the VRC-NOLM. The laser generates stable rectangular pulses with a low repetition rate (kilohertz magnitude) by extending the length of the cavity. Furthermore, the output pulse width of the fiber laser can be varied by changing the coupler ratio of the variable ratio coupler.
Nuclear-magnetic-resonance quantum calculations of the Jones polynomial
Marx, Raimund; Fahmy, Amr; Kauffman, Louis; Lomonaco, Samuel; Spörl, Andreas; Pomplun, Nikolas; Schulte-Herbrüggen, Thomas; Myers, John M.; Glaser, Steffen J.
The repertoire of problems theoretically solvable by a quantum computer recently expanded to include the approximate evaluation of knot invariants, specifically the Jones polynomial. The experimental implementation of this evaluation, however, involves many known experimental challenges. Here we present experimental results for small-scale approximate evaluation of the Jones polynomial by nuclear magnetic resonance (NMR); in addition, we show how to escape from the limitations of NMR approaches that employ pseudopure states. Specifically, we use two spin-1/2 nuclei of natural abundance chloroform and apply a sequence of unitary transforms representing the trefoil knot, the figure-eight knot, and the Borromean rings. After measuring the nuclear spin state of the molecule in each case, we are able to estimate the value of the Jones polynomial for each of the knots. PMID:21461143
Topological effects in the thermal properties of knotted polymer rings
Yani Zhao; Franco Ferrari
The topological effects on the thermal properties of several knot configurations are investigated using Monte Carlo simulations. In order to check if the topology of the knots is preserved during the thermal fluctuations we propose a method that allows very fast calculations and can be easily applied to arbitrarily complex knots. As an application, the specific energy and heat capacity of the trefoil, the figure-eight and the $8_1$ knots are calculated at different temperatures and for different lengths. Short-range repulsive interactions between the monomers are assumed. The knots configurations are generated on a three-dimensional cubic lattice and sampled by means of the Wang-Landau algorithm and of the pivot method. The obtained results show that the topological effects play a key role for short-length polymers. Three temperature regimes of the growth rate of the internal energy of the system are distinguished.
NMR Quantum Calculations of the Jones Polynomial
Raimund Marx; Amr Fahmy; Louis Kauffman; Samuel Lomonaco; Andreas Spörl; Nikolas Pomplun; John Myers; Steffen J. Glaser
The repertoire of problems theoretically solvable by a quantum computer recently expanded to include the approximate evaluation of knot invariants, specifically the Jones polynomial. The experimental implementation of this evaluation, however, involves many known experimental challenges. Here we present experimental results for a small-scale approximate evaluation of the Jones Polynomial by nuclear-magnetic resonance (NMR), in addition we show how to escape from the limitations of NMR approaches that employ pseudo pure states. Specifically, we use two spin 1/2 nuclei of natural abundance chloroform and apply a sequence of unitary transforms representing the Trefoil Knot, the Figure Eight Knot and the Borromean Rings. After measuring the state of the molecule in each case, we are able to estimate the value of the Jones Polynomial for each of the knots.
Introduction to Khovanov Homologies. II. Reduced Jones superpolynomials
V. Dolotin; A. Morozov
A second part of detailed elementary introduction into Khovanov homologies. This part is devoted to reduced Jones superpolynomials. The story is still about a hypercube of resolutions of a link diagram. Each resolution is a collection of non-intersecting cycles, and one associates a 2-dimensional vector space with each cycle. Reduced superpolynomial arises when for all cycles, containing a "marked" edge of the link diagram, the vector space is reduced to 1-dimensional. The rest remains the same. Edges of the hypercube are associated with cut-and-join operators, acting on the cycles. Superpartners of these operators can be combined into differentials of a complex, and superpolynomial is the Poincare polynomial of this complex. HOMFLY polynomials are practically the same in reduced and unreduced case, but superpolynomials are essentially different, already in the simplest examples of trefoil and figure-eight knot.
Holbrow, Charles H
Earth's analemma is the lopsided figure eight marked out over a year by the position of the Sun in the sky observed at the same clock time each day. It shows how solar time deviates from clock time. The analemma's shape results from the tilt of Earth's axis of rotation relative to the plane of its orbit around the Sun and from the elliptical shape of that orbit. This tutorial paper uses vector analysis of the Earth-Sun geometry and a numerically generated quantitative description of Earth's motion around the Sun to construct Earth's analemma. To visualize the geometry and the motion that give rise to the analemma is challenging, but this construction is a project within the capability of physics students who have had basic undergraduate mechanics.
Magnetic Resonance Imaging of time-varying magnetic fields from therapeutic devices
Hernandez-Garcia, Luis; Bhatia, Vivek; Prem-Kumar, Krishan; Ulfarsson, Magnus
While magnetic resonance imaging of static magnetic fields generated by external probes has been previously demonstrated, there is an unmet need to image time-varying magnetic fields, such as those generated by transcranial magnetic stimulators or radiofrequency hyperthermia probes. A method to image such time-varying magnetic fields is introduced in this work. This article presents the theory behind the method and provides proof of concept by imaging time-varying magnetic fields generated by a figure-eight coil inside simple phantoms over a range of frequencies and intensities, using a 7T small animal MRI scanner. The method is able to reconstruct the three-dimensional components of the oscillating magnetic field vector. PMID:23355446
The Penguin: a Low Reynolds Number Powered Glider for Station Keeping Missions
NASA Technical Reports Server (NTRS)
Costello, J. K.; Greene, D. W.; Lee, T. T.; Matier, P. T.; Mccarthy, T. R.; Mcguire, R. J.; Schuette, M. J.
The Penguin is a low Reynolds number (approx. 100,000) remotely piloted vehicle (RPV). It was designed to fly three laps indoors around two pylons in a figure-eight course while maximizing loiter time. The Penguin's low Reynolds number mission is an important one currently being studied for possible future flights in the atmospheres of other planets and for specialized military missions. Although the Penguin's mission seemed quite simple at first, the challenges of such low Reynolds number flight have proven to be quite unique. In addition to the constraint of low Reynolds number flight, the aircraft had to be robust in its control, highly durable, and it had to carry a small instrument package. The Penguin's flight plan, concept, performance, aerodynamic design, weight estimation, structural design, propulsion, stability and control, and cost estimate is detailed.
NSDL National Science Digital Library
Anne Jefferson
To prepare for the case study, lecture material on coastal landforms and processes is presented. Particular attention is paid to barrier islands, such as the Outer Banks. During the lecture, typical coastal engineering structures, such as groins, breakwaters, and jetties, are introduced. The case study is introduced with a brief overview of North Carolina's coastal management laws, Figure Eight Island's geography, and the current controversy over whether to build a terminal groin. Students are then broken down into small groups and presented with two opposing editorials. The groups are instructed to try to come to consensus as to whether the terminal groin should be allowed or disallowed or to suggest a third alternative. After approximately 25 minutes, each group informally reports out to the rest of the class.
Nuclear-magnetic-resonance quantum calculations of the Jones polynomial
Marx, Raimund; Spoerl, Andreas; Pomplun, Nikolas; Schulte-Herbrueggen, Thomas; Glaser, Steffen J. [Department of Chemistry, Technische Universitaet Muenchen, Lichtenbergstr. 4, D-85747 Garching (Germany); Fahmy, Amr [Biological Chemistry and Molecular Pharmacology, Harvard Medical School, 240 Longwood Avenue, Boston, Massachusetts 02115 (United States); Kauffman, Louis [University of Illinois at Chicago, 851 S. Morgan Street, Chicago, Illinois 60607-7045 (United States); Lomonaco, Samuel [University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, Maryland 21250 (United States); Myers, John M. [Cruft Laboratory, Harvard University, 19 Oxford Street, Cambridge, Massachusetts 02138 (United States)
The repertoire of problems theoretically solvable by a quantum computer recently expanded to include the approximate evaluation of knot invariants, specifically the Jones polynomial. The experimental implementation of this evaluation, however, involves many known experimental challenges. Here we present experimental results for a small-scale approximate evaluation of the Jones polynomial by nuclear magnetic resonance (NMR); in addition, we show how to escape from the limitations of NMR approaches that employ pseudopure states. Specifically, we use two spin-1/2 nuclei of natural abundance chloroform and apply a sequence of unitary transforms representing the trefoil knot, the figure-eight knot, and the Borromean rings. After measuring the nuclear spin state of the molecule in each case, we are able to estimate the value of the Jones polynomial for each of the knots.
A New Solution to the Three Body Problem
NSDL National Science Digital Library
Casselman, Bill.
The subject of this month's feature column from the American Mathematical Society Online is the solution to the "Three Body Problem" of Newtonian mechanics. The problem deals with three orbiting bodies of equal mass and the paths that they will take relative to one another. Solutions have been proposed by many, including Euler, Lagrange, and G.W. Hill. The article notes that solutions are sometimes called "choreographies." The well-written explanatory text discusses the figure-eight orbit, the triangle construction, other choreographies with >3 bodies, and the search for exotic orbits. It includes user-driven Java applets as demonstrations. This site should be interesting to mathematicians and non-mathematicians alike.
Performance limitations due to ASE and intraband crosstalk in FBG-OC-based bidirectional OXCs in a WDM ring network
Mohammad Rezaul Karim; S. P. Majumder
We investigate the effects of optical amplifiers in the presence of intraband crosstalk arises in FBG-OC-based bidirectional optical cross connects (BOXCs) for bidirectional WDM ring networks (BWRNs). Theoretical analysis is carried out to evaluate the performance limitations due to ASE of optical amplifiers in bidirectional WDM ring networks. We analyzed here two configurations of FBG-OC-based BOXCs: 2 × 2 BOXC
Dynamic LSP Provisioning in Overlay, Augmented, and Peer Architectures for IP\\/MPLS over WDM Networks
Sunggy Koo; Gokhan Sahin; Suresh Subramaniam
We consider an IP\\/MPLS over WDM network, in which label switched routers (LSRs) in the IP\\/MPLS layer are interconnected through optical cross-connects (OXCs) in the optical core network (WDM layer) providing an end-to-end wavelength routing capability. In this paper, we study a dynamic label switched path (LSP) provisioning problem for the three different network models of the IP\\/MPLS over WDM
Resource Management in STARGATE-Based Ethernet Passive Optical Networks (SG-EPONs)
Lehan Meng; Chadi M. Assi; Martin Maier; Ahmad R. Dhaini
At present there is a strong worldwide push toward bringing fiber closer to individual homes and businesses. Another evolutionary step is the cost-effective all-optical integration of fiber-based access and metro networks. STARGATE (IEEE Commun. Mag., vol. 45, no. 5, pp. 50-56, May 2007) is an all-optical access-metro architecture that does not rely on costly active devices, e.g., optical cross connects
A Novel Integrated Multistage 2-D MEMS Optical Switch With Spanke–Benes Architecture
Guomei Zhu
Due to the emergence of high-capacity wavelength-division multiplexing transmission systems, new optical cross-connect (OXC) architectures that make a large number of fiber\\/wavelength counts to switch the signal in the optical domain are needed. Optical microelectromechanical system (MEMS) switches are regarded as the most promising optical switch technology to achieve such functionalities. In this paper, we propose a novel integrated multistage
Performance studies of a selfhealing network protocol in Telecom Canada long haul networks
W. D. Grover; B. D. Venables; J. H. Sandham; A. F. Mine
Telecom Canada commissioned a study to verify the speed and routing performance of a newly developed self-healing network (SHN) restoration technique. The particular SHN protocol is based on a unique paradigm for rapid, distributed, physical-layer interaction among digital cross-connect system (DCS) machines. An implementation of the protocol, as it would be installed in a DCS machine, was executed concurrently in
All-Optical Label Swapping of Scalable In-Band Address Labels and 160Gb\\/s Data Packets
Nicola Calabretta; Hyun-Do Jung; Javier Herrera Llorente; Eduward Tangdiongga; Ton A. M. J. Koonen; Harm J. S. Dorren
Scalability and photonic integration of packet switched cross-connect nodes that utilize all-optical signal processing is a crucial issue that eventually determines the future role of photonic signal processing in optical networks. We present a 1times4 all-optical packet switch based on label swapping technique that utilizes a scalable and asynchronous label processor and label rewriter. By combining N in-band labels at
An optimal spare-capacity assignment model for survivable networks with hop limits
Meir Herzberg; Stephen J. Bye
The paper presents a new algorithm for spare-capacity assignment in survivable networks which use cross-connect systems as transmission hubs. The algorithm minimises total cost of spare capacity for required levels of network restoration following a single link failure (e.g. fibre cut) and limits the restoration routes to any predetermined hop limit. The algorithm is composed of two parts: Part 1
S. Ramamurthy; Laxman Sahasrabuddhe; Biswanath Mukherjee
Abstract, In a wavelength-division-muliplexing (WDM) optical network, the failure of network elements (e. g., fiber links and cross connects) may cause the failure of several optical channels, thereby leading to large data losses. This study examines different approaches to protect a mesh-based WDM optical network from such failures. These approaches are based on two survivability paradigms: 1) path protection\\/restoration and
Advances in polymer-based dynamic photonic components, modules, and subsystems
Louay Eldada
We describe recent advances in optical communication components, modules, and subsystems based on planar polymer technologies. The dynamic organic photonic integrated circuits exhibit ultra low power consumption through thermo-optic actuation for switching, routing, and tuning. The components (switches, optical cross-connects (OXC), variable optical attenuators (VOA), tunable couplers, etc.) have state-of-the-art performance, meet reliability requirements in the telecommunication industry including Telcordia
Dissolved Organic Matter Dynamics in two Suburban Catchments in NE England
NASA Astrophysics Data System (ADS)
Baker, A.; Simpson, E.; Bryant, C.
Recent advances in fluorescence spectrophotometry enable rapid and optically precise analysis of river dissolved organic matter (DOM). In this study we investigate the potential of detecting river pollution associated with urban expansion (cross connected sewerage; overloading of combined sewer overflows (CSOs), land use change) using fluorescence and absorbance spectrophotometry, paired with conventional geochemistry, microbiological analyses and 14C/13C isotope fingerprinting of dissolved organic matter, in two small, rural-urban fringe catchments in NE England over the period 2002-present. In the United Kingdom, `suburbia' (post 1945AD) is distinguished by separate sewerage systems and associated issues of cross connections. Results indicate: (1) suburban catchments have a seasonal trend in DOM fluorescence, with a maximum of tryptophan-like fluorescence in summer low flow, indicative of an increased proportion of cross connected sewer inputs, with a statistically significant inverse relationship with discharge. Older `urban' catchments with CSOs exhibit an opposite seasonality, with combined sewerage overflows occurring in winter at high flow due to CSO discharge. (2) Sampling cross connected storm drains for both Escherichia coli. and fluorescence demonstrates a statistically significant relationship. This finding matches laboratory microbial cultures, which have demonstrated that a wide range of environmentally relevant microbes exhibit tryptophan-like fluorescence, and suggests that when coliforms dominate a river or wastewater microbial community then fluorescence intensity could potentially be employed to monitor faecal coliforms in urban waters. (3) 14C/13C fingerprinting of DOM in three contrasting sub-catchments separates urban and industrial DOM sources through positive 13C and `old' 14C.
The EXC management in the OTN over WDM network
Huibin Zhang; Jie Zhang; Yongli Zhao; Dahai Han; Pei Zhang
The OTN over WDM network is one of the best solutions of the optical transmission network. As a traditional multi-layer network, multi-layer traffic grooming algorithms in the OTN over WDM network have been fully studied. However, the cross-connects capacity management problem of the OTN node in the OTN over WDM network is still under study. In our previous work, an
1296-port MEMS transparent optical crossconnect with 2.07 petabit\\/s switch capacity
R. Ryf; J. Kim; J. P. Hickey; A. Gnauck; D. Carr; F. Pardo; C. Bolle; R. Frahm; N. Basavanhally; C. Yoh; D. Ramsey; R. Boie; R. George; J. Kraus; C. Lichtenwalner; R. Papazian; J. Gates; H. R. Shea; A. Gasparyan; V. Muratov; J. E. Griffith; J. A. Prybyla; S. Goyal; C. D. White; M. T. Lin; R. Ruel; C. Nijander; S. Arney; D. T. Neilson; D. J. Bishop; P. Kolodner; S. Pau; C. Nuzman; A. Weis; B. Kumar; D. Lieuwen; V. Aksyuk; D. S. Greywall; T. C. Lee; H. T. Soh; W. M. Mansfield; S. Jin; W. Y. Lai; H. A. Huggins; D. L. Barr; R. A. Cirelli; G. R. Bogart; K. Teffeau; R. Vella; H. Mavoori; A. Ramirez; N. A. Ciampa; F. P. Klemens; M. D. Morris; T. Boone; J. Q. Liu; J. M. Rosamilia; C. R. Giles
A 1296-port MEMS transparent optical crossconnect with 5.1dB±1.1dB insertion loss at 1550 nm is reported. Measured worst-case optical crosstalk in a fabric was n38 dB and nominal switching rise\\/fall times were 5 ms. A 2.07 petabit\\/s switch capacity was verified upon cross-connecting a forty-channel by 40 Gb\\/s DWDM data stream through a prototype fabric.
An algorithm for virtual topology design in WDM optical networks under physical constraints
Ji Yon Youe; Seung-Woo Seo
Although designing a virtual topology for all-optical WDM wide-area networks has been extensively studied and several algorithms have been proposed, these algorithms assume error-free communication between two nodes. However, noises from optical amplifiers and optical cross-connects can degrade the signal, resulting in a nonzero bit-error rate. In this paper, we investigate the effect of physical limitations on the virtual topology
Cycle-oriented distributed preconfiguration: ring-like speed with mesh-like capacity for self-planning network restoration
Wayne D. Grover; Demetrios Stamatelakis
Cycle-oriented preconfiguration of spare capacity is a new idea for the design and operation of mesh-restorable networks. It offers a sought-after goal: to retain the capacity-efficiency of a mesh-restorable network, while approaching the speed of line-switched self-healing rings. We show that through a strategy of pre-failure cross-connection between the spare links of a mesh network, it is possible to achieve
Self-healing rings in a synchronous environment
I. Haque; W. Kremer; K. Raychaudhuri
An overview of different self-healing network architectures, focusing on ring architectures, is presented. Digital cross-connect systems-based self-healing and diversely routed protection are briefly discussed. Since a typical self-healing network design may use all of the self-healing architectures, a discussion on applications perspectives, illustrating how the various self-healing technologies may best fit in the evolving network, is included
Dynamic bandwidth-allocation and path-restoration in SONET self-healing networks
A. Gersht; S. Kheradpir; A. Shulman
This paper presents a new scheme for real-time bandwidth allocation and path restoration (BARS) in mesh networks via SONET wideband digital cross-connect systems (WDCSs) in response to demand and load dynamics and link and\\/or node failure(s). The scheme dynamically maximizes bandwidth allocation while ensuring full service restorability. Since the physical network capacity is limited, sometime not all the demand can
A self-healing network with an economical spare-channel assignment
Hideki Sakauchi; Y. Nishimura; S. Hasegawa
With the advent of networking technologies intelligent network elements, such as the digital cross-connect system (DCS), will make it possible to dynamically reconfigure a network for restoration purposes. Both restoration control of DCSs and spare-channel design issues are presented, and how they work together so that a fast and economical SONET self-healing network is obtained. In order to achieve fast
ALOHA\\/Slotted-CSMA Protocol for a Very High-Speed Optical Fiber Local Area Network Using Passive Star Topology
Haixing Shi; Mohsen Kavehrad
A protocol for a multiuser very high-speed optical data network based on a passive star topology is presented and analyzed. The users' traffic is assumed to be bursty as in the case of computer communications. Tunable transmitters and receivers which are capable of tuning to N+1 relatively stable wavelengths are required to be cross-connected via a passive optical star coupler
Cross-linker system between neurofilaments, microtubules and membranous organelles in frog axons revealed by the quick-freeze, deep-etching method
Hirokawa, N
The elaborate cross-connections among membranous organelles (MO), microtubules (MT), and neurofilaments (NF) were demonstrated in unifixed axons by the quick-freeze, deep-etch, and rotary-shadowing method. They were categorized into three groups: NF-associated cross-linker, MT-associated cross-bridges, and long cross-links in the subaxolemmal space. Other methods were also employed to make sure that the observed cross-connections in the unfixed axons were not a result of artifactual condensation or precipitation of soluble components or salt during deep-etching. Axolemma were permeablized either chemically (0.1% saponin) or physically (gentle homogenization), to allow egress of their soluble components from the axon; or else the axons were washed with distilled water after fixation. After physical rupture of the axolemma or saponin treatment, most of the MO remained intact. MT were stabilized by adding taxol in the incubation medium. Axons prepared by these methods contained many longitudinally oriented NF connected to each other by numerous fine cross-linkers (4-6 nm in diameter, 20-50 nm in length). Two specialized regions were apparent within the axons: one composed of fascicles of MT linked with each other by fine cross-bridges; the other was in the subaxolemmal space and consisted of actinlike filaments and a network of long cross-links (50-150 nm) which connected axolemma and actinlike filaments with NF and MT. F-actin was localized to the subaxolemmal space by the nitrobenzooxadiazol phallacidin method. MO were located mainly in these two specialized regions and were intimately associated with MT via fine short (10-20 nm in length) cross-bridges. Cross-links from NF to MO and MT were also common. All these cross-connections were observed after chemical extraction or physical rupture of the axon; however, these procedures removed granular materials which were attached to the filaments in the fresh unextracted axons. The cross-connections were also found in the axons washed with distilled water after fixation. I conclude that the cross- connections are real structures while the granular material is composed of soluble material, probably protein in nature. PMID:6181077
Novel cryogen-free actively shielded superconducting magnets for maglev vehicles. Final report, August 1991-June 1992
Vermilyea, M.E.
The report presents the results of a research effort into the design of a shielded superconducting magnet system for a maglev vehicle. The magnet design is based on a novel cryogen-free technology which allows operation without the use of any cryogenic fluids. This is accomplished by the use of a two-stage Gifford-McMahon (G-M) cryogenic refrigerator to provide cooling of the coil and a single cryostat thermal radiation shield by conduction. The design operating temperature of the magnet is 7.5 K, and that of the shield is 43 K. The magnet is wound with a tape form of niobium tin superconductor which allows operation at a module current density of 8100 A/sq cm at a flux density of 3.4 T at the 7.5 K temperature with a margin of 4.5 K to critical temperature. The magnet design is coupled with a linear synchronous motor and null-flux sidewall levitation system to provide a workable maglev system design. Costs for several components of the design, including coils and cryostat, shielding, and power conditioning apparatus are estimated.
Toroidal Dehn surgeries on knots in lens spaces
NASA Astrophysics Data System (ADS)
McA. Gordon, C.
Let M be a compact, orientable 3-manifold with [partial partial differential]M a torus. If r is a slope on [partial partial differential]M (the isotopy class of an unoriented essential simple loop), then we can form the closed 3-manifold M(r) by gluing a solid torus Vr to M along their boundaries in such a way that r bounds a disc in Vr. We say that M(r) is obtained from M by r-Dehn filling.Assume now that M contains no essential sphere, disc, torus or annulus. Then, by Thurston's Geometrization Theorem for Haken manifolds [T1, T2], M is hyperbolic, in the sense that int M has a complete hyperbolic structure of finite volume. Furthermore, M(r) is hyperbolic for all but finitely many r [T1, T2] and the precise nature of the set of exceptional slopes E(M)={r: M(r) is not hyperbolic} has been the subject of a considerable amount of investigation. The maximal observed value of e(M)=[mid R:]E(M)[mid R:] (the cardinality of E(M)) is 10, realized, apparently uniquely, by the exterior of the figure eight knot [T1].Let [Delta](r1, r2) denote as usual the minimal geometric intersection number of two slopes r1 and r2. If [script S] is any set of slopes, then clearly any upper bound for [Delta]([script S])=max{[Delta](r1, r2): r1, r2[set membership][script S]} gives one for [mid R:][script S][mid R:]. For example, one can check (using [GLi, lemma 2·1]) that for 1[less-than-or-eq, slant][Delta]([script S])[less-than-or-eq, slant]10, the maximum values of [mid R:][script S][mid R:] are as given in Table 1.In particular, any upper bound for [Delta](M)=[Delta](E(M)) gives a corresponding bound for e(M). (The maximal observed value of [Delta](M) is 8, realized by the figure eight knot exterior and the figure eight sister manifold [T1, HW].)If M(r) is not hyperbolic, then it is either reducible (contains an essential sphere), toroidal (contains an essential torus), a small Seifert fibre space (one with base S2 and at most three singular fibres), or a counterexample to the Geometrization Conjecture [T1, T2]. A survey of the presently known upper bounds on the distances [Delta](r1, r2) between various classes of exceptional slopes r1 and r2, and the maximal values realized by known examples, is given in [Go2]. (See also [Wu2] for a discussion of the additional cases that arise when M has more than one boundary component.) In the present note we prove the following theorem, which deals with one further pair of possibilities.
Power Generation and Power Use Decisions in an Industrial Process
Gilbert, J. S.; Niess, R. C.
at the reboiler or as the heat exchanger of the evaporator, most real life processes use steam for a simple reason. It uncouples one distillation column or evaporator from dependence on another unit. Realistically, cross connecting these units would result... in many operating problems. That's why most plants don't couple a distillation tower using the waste heat from another for this reason. The process looks good and is interesting, but in reality the reboiler or the evaporator heater will be steam fired...
Microwave photonic filters using low-cost sources featuring tunability, reconfigurability and negative coefficients.
Capmany, José; Mora, José; Ortega, Beatriz; Pastor, Daniel
We propose and experimentally demonstrate two configurations of photonic filters for the processing of microwave signals featuring tunability, reconfigurability and negative coefficients based on the use of low cost optical sources. The first option is a low power configuration based on spectral slicing of a broadband source. The second is a high power configuration based on fixed lasers. Tunability, reconfigurability and negative coefficients are achieved by means of a MEMS cross-connect, a variable optical attenuator array and simple 2x2 switches respectively. PMID:19495017
Novel lens design for free-space optical interconnects
NASA Astrophysics Data System (ADS)
Ramsey, J. L.; Pijitrojana, W.; Hall, T. J.
The transposition of signals in space is fundamental to the optical interconnection of electronic systems. Previous free-space implementations employed a scheme based on imaging systems that are prone to aberrations. The system proposed here is useful for implementation of a three-stage Clos network, an optical transpose sector switch, a reconfigurable optical transpose system, and an optical cross connect switch. The purpose of this paper is to propose a non-imaging system for an optical transpose interconnect system, where a macrolens is inserted between the two mesolenses arrays, at the centre. The proposed macrolens is a Fourier transform lens system designed to be virtually aberration free.
Spatial Light Modulators as Optical Crossbar Switches
NASA Technical Reports Server (NTRS)
Juday, Richard
A proposed method of implementing cross connections in an optical communication network is based on the use of a spatial light modulator (SLM) to form controlled diffraction patterns that connect inputs (light sources) and outputs (light sinks). Sources would typically include optical fibers and/or light-emitting diodes; sinks would typically include optical fibers and/or photodetectors. The sources and/or sinks could be distributed in two dimensions; that is, on planes. Alternatively or in addition, sources and/or sinks could be distributed in three dimensions -- for example, on curved surfaces or in more complex (including random) three-dimensional patterns.
Fiber-channel trade-off for reducing collisions in slotted single-hop optical packet-switched networks
Akbar Ghaffar Pour Rahbar; Oliver Yang
The next-generation Internet should be based on high-capacity agile all-optical networks. A single-hop time-slotted all-optical packet-switched network is studied as a potential candidate for the ultra-high-speed next-generation all-optical metro network. This structure is composed of an all-optical wavelength-selective cross-connect core switch and a number of edge switches connected to the core switch in a star physical topology. Since optical packet
Real-time distributed processing in the Mt. Wilson 100-inch Hooker telescope adaptive optics system
NASA Astrophysics Data System (ADS)
Schneider, Thomas G.; Shelton, J. Christopher
The Adoptics software used with the Hooker telescope's ADOPT adaptive optics system implements real-time control on a network of eight Texas Instruments C40 40Mhz DSP processors. System inputs and outputs consist of a 32 port 4 fiber wavefront sensor CCD with 32 X 32 pixels, a tilt mirror and a deformable mirror of which 241 elements are actively controlled. The network os eight DSP processors is configured as two cross-connected rings of four processors each. Four input sites perform intensity and gradient calculations immediately on incoming pixels as well as passing pixels on to adjacent sites for parallel calculations.
Crystal and molecular structure of didemnin B, an antiviral and cytotoxic depsipeptide.
Hossain, M B; van der Helm, D; Antel, J; Sheldrick, G M; Sanduja, S K; Weinheimer, A J
Didemnin B, a highly active depsipeptide isolated from a Caribbean tunicate, crystallizes from chloroform/benzene in the orthorhombic space group C2221, with cell parameters a = 14.990 +/- 0.003 A, b = 22.574 +/- 0.004 A, c = 41.112 +/- 0.009 A, V = 13911.7 A3 at 138 K and a calculated density of 1.143 g/cm3 based on C57H89N7O15, 1.5C6H6.H2O and eight formula units per cell. The overall agreement factor R = 0.052 for 7699 reflections, 20 theta max = 150 degrees, Cu K-alpha radiation. The structure determination revealed that didemnin B contains an isostatine residue instead of a statine residue. The conformation of the 23-membered depsipeptide ring is stabilized by one transannular hydrogen bond. The ring does not show the antiparallel beta-pleated-sheet structure but, instead, has a fold in the shape of a bent figure-eight. The linear peptide moiety, containing N-methylleucine and lactylproline, forms a beta (II)-bend and is folded back toward the cyclic backbone, giving the overall molecule a globular character. Comparison with the structure of cyclosporin A shows distinct stereochemical differences between the two molecules. It is suggested that didemnin B and cyclosporin A are unlikely to have a common receptor binding site. PMID:3380783
Preliminary observations on the response of Chironex fleckeri (Cnidaria: Cubozoa: Chirodropida) to different colors of light.
Gershwin, Lisa-Ann; Dawes, Peter
Cubozoans are well known for their attraction to light and light-colored objects. Two highly venomous types are a public safety concern in Australian waters and elsewhere: Chironex fleckeri, long considered the world's deadliest animal and colloquially called the box jellyfish; and the irukandjis, a group of at least 10 species that cause various degrees of debilitating illness. We were asked by the tourism industry whether there might be a color of light that box jellyfish and irukandjis are not attracted to, such that nighttime diving activities might pose less risk of being stung. Our preliminary trials with Chironex fleckeri indicated a marked positive response to lights of white, red, yellow, green, orange, and blue. All colors elicited a strong and directed attraction to light; however, medusae slowed down their pulsation rate, streamed out their tentacles, and performed a series of figure-eight patterns back and forth through the lighted area when exposed to blue light, which we interpreted as feeding behavior. This compares curiously with a report subsequent to our testing, in which the small, mangrove-inhabiting cubomedusa Tripedalia cystophora and the beach-dwelling Chiropsella bronzie demonstrate a peak sensitivity to blue-green light in the region of 500 nm, and that the former is behaviorally attracted to blue and green light, but ignores red. This leaves open the possibility that Irukandji species, which are more closely related to Tripedalia than to Chironex, may be blind to red. PMID:18723637
All-order asymptotics of hyperbolic knot invariants from non-perturbative topological recursion of A-polynomials
Borot, Gaëtan
We propose a conjecture to compute the all-order asymptotic expansion of the colored Jones polynomial of the complement of a hyperbolic knot, J_N(q = exp(2u/N)) when N goes to infinity. Our conjecture claims that the asymptotic expansion of the colored Jones polynomial is a the formal wave function of an integrable system whose semiclassical spectral curve S would be the SL_2(C) character variety of the knot (the A-polynomial), and is formulated in the framework of the topological recursion. It takes as starting point the proposal made recently by Dijkgraaf, Fuji and Manabe (who kept only the perturbative part of the wave function, and found some discrepancies), but it also contains the non-perturbative parts, and solves the discrepancy problem. These non-perturbative corrections are derivatives of Theta functions associated to S, but the expansion is still in powers of 1/N due to the special properties of A-polynomials. We provide a detailed check for the figure-eight knot and the once-punctured torus bundle...
PIV Measurements in Model and Full Scale Coal Mines
NASA Astrophysics Data System (ADS)
Rangubhotla, Lavanya; Jacob, Jamey; Wala, Andrew; Taylor, Charles
The present research focuses on examining effective ventilation in a coal mine using PIV. The purpose of these experiments is to study in detail the flow characteristics in a 1:15 scale mine model and compare it with a full-scale mine to develop effective means of face ventilation in a coal mine. PIV measurements were conducted in the prototype model with various channel geometries with width to height ratios of 1.7 to 4 and length to height ratios of 2 to 5, with and without slabs. Gross separation was observed to occur immediately downstream of the ventilation exit (curtain) in all cases below a critical channel width resulting in a figure eight pattern and drastically reduced face ventilation. PIV measurements taken on a full-scale mine model (6.1 m wide by 18.3 m long) at NIOSH displayed similar flow patterns, including separation immediately downstream of the curtain resulting in inadequate ventilation. In addition to time-averaged and unsteady velocity fields, volumetric flow rates, wall skin friction in the separation region, and possible methods of improved face ventilation are presented.
Phase drift between the in-line and cross-flow vortex-induced vibrations of a long flexible cylinder in shear flow
NASA Astrophysics Data System (ADS)
Bourguet, Remi; Karniadakis, George; Triantafyllou, Michael
Long flexible structures with bluff cross-sections placed in cross-flow exhibit vortex- induced vibrations. The in-line and cross-flow vibrations generally occur with a frequency ratio of two leading to figure-eight orbits in the plane perpendicular to the span. The structure is excited by the flow under a lock-in condition defined as the synchronization between vortex shedding and body displacement. Previously, we have shown that, in sheared current, the region of lock-in is characterized by trajectories where the structure moves upstream at the extremes of the cross-flow motion. Recent experimental and numerical studies have emphasized a phenomenon of phase drift between in-line and cross-flow vibrations dominated by traveling waves, that induces a continuous change in the shape and orientation of the flexible body orbit along the span. In the present work, we elucidate the link between this phenomenon and the departure from a ratio of two between the in-line and cross-flow excited structural wavenumbers and we show, by means of numerical simulation, that the effective added mass in each direction controls the phase drift.
Super-A-polynomial for knots and BPS states
NASA Astrophysics Data System (ADS)
Fuji, Hiroyuki; Gukov, Sergei; Su?kowski, Piotr
We introduce and compute a 2-parameter family deformation of the A-polynomial that encodes the color dependence of the superpolynomial and that, in suitable limits, reduces to various deformations of the A-polynomial studied in the literature. These special limits include the t-deformation which leads to the "refined A-polynomial" introduced in the previous work of the authors and the Q-deformation which leads, by the conjecture of Aganagic and Vafa, to the augmentation polynomial of knot contact homology. We also introduce and compute the quantum version of the super-A-polynomial, an operator that encodes recursion relations for Sr-colored HOMFLY homology. Much like its predecessor, the super-A-polynomial admits a simple physical interpretation as the defining equation for the space of SUSY vacua (= critical points of the twisted superpotential) in a circle compactification of the effective 3d N=2 theory associated to a knot or, more generally, to a 3-manifold M. Equivalently, the algebraic curve defined by the zero locus of the super-A-polynomial can be thought of as the space of open string moduli in a brane system associated with M. As an inherent outcome of this work, we provide new interesting formulas for colored superpolynomials for the trefoil and the figure-eight knot.
[Anisotropic impulse conduction characteristics in chronic myocardial infarct. The importance for initiation and perpetuation of ventricular tachycardia].
Kottkamp, H; Hindricks, G; Haverkamp, W; Shenasa, M; Borggrefe, M; Breithardt, G
The underlying mechanism of most ventricular tachycardias in the setting of chronic myocardial infarction is reentrant excitation. At that time, the active membrane properties like upstroke velocity and amplitude of action potentials of muscle fibers surviving in the border zone of the infarction have returned nearly completely to normal. Anisotropic conduction characteristics, however, importantly contribute to the electrophysiologic properties of the epicardial and/or endocardial border zones in chronic myocardial infarction. In normal myocardial tissue with tight coupling between muscle fibers, conduction velocity is slower for impulses propagating transverse to fiber orientation compared to longitudinal to fiber orientation due to a higher effective axial resistivity ("uniform" anisotropy). With infarct healing, connective tissue invading into the epicardial border zone separates surviving muscle fiber bundles and thereby decreases cell-to-cell coupling ("non-uniform" anisotropy). In this setting, excitation waves propagate transverse to fiber orientation in an irregular sequence and conduction velocity in this direction is significantly reduced without occurrence of acute ischemia. Block of conduction waves propagating longitudinally to fiber orientation may lead to activation of the area distal to the block with long delay by very slow transverse wavefronts. This long delay allows fibers proximal to the line of block to regenerate excitability, and reentrant excitation may be initiated. The common pathway of figure-eight tachycardias preferentially orientates longitudinally to fiber orientation. Very slow conduction transverse to fiber orientation at the pivoting points of reentrant circuits may lead to the occurrence of excitable gaps. PMID:8506717
Torus Knots and Links from Eikonal Equations and Knot Invariants for Classification of Atoms
NASA Astrophysics Data System (ADS)
Elrifai, E. A.
The history of knot theory and physics has a deep roots. It started by Lord Kelvin, in 1867, when he conjectured that atoms were knotted vortex tubes of ether. In 1997, Faddeev and Niemi suggested that knots might exist as stable soliton solution in a simple three dimensional classical field theory. That opening up a wide range of possible applications in physics. In this work we consider the Eikonal equation, which is a partial differential equation describing the traveltime propagation, which is an important part of seismic imaging algorithms. We will follow the work of Wereszczynski of solving the Eikonal equation in cylindrical coordinates. We show that only torus knots and links do occur, so figure eight knot does not occur. We show that these solutions are not unique, which means the possible occurrence of the same knot type for different configurations. Using the idea of framed knots, it is shown that two Eikonal knots are equivalent if and only if they are ambient isotopic as a framed knots, i.e. if and only if they are of the same knot type and of the same twisting number.
Bulk mixed ion electron conduction in amorphous gallium oxide causes memristive behaviour
NASA Astrophysics Data System (ADS)
Aoki, Yoshitaka; Wiemann, Carsten; Feyer, Vitaliy; Kim, Hong-Seok; Schneider, Claus Michael; Ill-Yoo, Han; Martin, Manfred
In thin films of mixed ionic electronic conductors sandwiched by two ion-blocking electrodes, the homogeneous migration of ions and their polarization will modify the electronic carrier distribution across the conductor, thereby enabling homogeneous resistive switching. Here we report non-filamentary memristive switching based on the bulk oxide ion conductivity of amorphous GaOx (x~1.1) thin films. We directly observe reversible enrichment and depletion of oxygen ions at the blocking electrodes responding to the bias polarity by using photoemission and transmission electron microscopies, thus proving that oxygen ion mobility at room temperature causes memristive behaviour. The shape of the hysteresis I-V curves is tunable by the bias history, ranging from narrow counter figure-eight loops to wide hysteresis, triangle loops as found in the mathematically derived memristor model. This dynamical behaviour can be attributed to the coupled ion drift and diffusion motion and the oxygen concentration profile acting as a state function of the memristor.
Bulk mixed ion electron conduction in amorphous gallium oxide causes memristive behaviour.
Aoki, Yoshitaka; Wiemann, Carsten; Feyer, Vitaliy; Kim, Hong-Seok; Schneider, Claus Michael; Ill-Yoo, Han; Martin, Manfred
In thin films of mixed ionic electronic conductors sandwiched by two ion-blocking electrodes, the homogeneous migration of ions and their polarization will modify the electronic carrier distribution across the conductor, thereby enabling homogeneous resistive switching. Here we report non-filamentary memristive switching based on the bulk oxide ion conductivity of amorphous GaOx (x~1.1) thin films. We directly observe reversible enrichment and depletion of oxygen ions at the blocking electrodes responding to the bias polarity by using photoemission and transmission electron microscopies, thus proving that oxygen ion mobility at room temperature causes memristive behaviour. The shape of the hysteresis I-V curves is tunable by the bias history, ranging from narrow counter figure-eight loops to wide hysteresis, triangle loops as found in the mathematically derived memristor model. This dynamical behaviour can be attributed to the coupled ion drift and diffusion motion and the oxygen concentration profile acting as a state function of the memristor. PMID:24632885
Vortex-induced vibrations of a flexible cylinder at large inclination angle.
Bourguet, Rémi; Triantafyllou, Michael S
The free vibrations of a flexible circular cylinder inclined at 80° within a uniform current are investigated by means of direct numerical simulation, at Reynolds number 500 based on the body diameter and inflow velocity. In spite of the large inclination angle, the cylinder exhibits regular in-line and cross-flow vibrations excited by the flow through the lock-in mechanism, i.e. synchronization of body motion and vortex formation. A profound reconfiguration of the wake is observed compared with the stationary body case. The vortex-induced vibrations are found to occur under parallel, but also oblique vortex shedding where the spanwise wavenumbers of the wake and structural response coincide. The shedding angle and frequency increase with the spanwise wavenumber. The cylinder vibrations and fluid forces present a persistent spanwise asymmetry which relates to the asymmetry of the local current relative to the body axis, owing to its in-line bending. In particular, the asymmetrical trend of flow-body energy transfer results in a monotonic orientation of the structural waves. Clockwise and counter-clockwise figure eight orbits of the body alternate along the span, but the latter are found to be more favourable to structure excitation. Additional simulations at normal incidence highlight a dramatic deviation from the independence principle, which states that the system behaviour is essentially driven by the normal component of the inflow velocity. PMID:25512586
How Do Honeybees Attract Nestmates Using Waggle Dances in Dark and Noisy Hives?
Hasegawa, Yuji; Ikeno, Hidetoshi
It is well known that honeybees share information related to food sources with nestmates using a dance language that is representative of symbolic communication among non-primates. Some honeybee species engage in visually apparent behavior, walking in a figure-eight pattern inside their dark hives. It has been suggested that sounds play an important role in this dance language, even though a variety of wing vibration sounds are produced by honeybee behaviors in hives. It has been shown that dances emit sounds primarily at about 250–300 Hz, which is in the same frequency range as honeybees' flight sounds. Thus the exact mechanism whereby honeybees attract nestmates using waggle dances in such a dark and noisy hive is as yet unclear. In this study, we used a flight simulator in which honeybees were attached to a torque meter in order to analyze the component of bees' orienting response caused only by sounds, and not by odor or by vibrations sensed by their legs. We showed using single sound localization that honeybees preferred sounds around 265 Hz. Furthermore, according to sound discrimination tests using sounds of the same frequency, honeybees preferred rhythmic sounds. Our results demonstrate that frequency and rhythmic components play a complementary role in localizing dance sounds. Dance sounds were presumably developed to share information in a dark and noisy environment. PMID:21603608
Differences in gaze anticipation for locomotion with and without vision
Authié, Colas N.; Hilt, Pauline M.; N'Guyen, Steve; Berthoz, Alain; Bennequin, Daniel
Previous experimental studies have shown a spontaneous anticipation of locomotor trajectory by the head and gaze direction during human locomotion. This anticipatory behavior could serve several functions: an optimal selection of visual information, for instance through landmarks and optic flow, as well as trajectory planning and motor control. This would imply that anticipation remains in darkness but with different characteristics. We asked 10 participants to walk along two predefined complex trajectories (limaçon and figure eight) without any cue on the trajectory to follow. Two visual conditions were used: (i) in light and (ii) in complete darkness with eyes open. The whole body kinematics were recorded by motion capture, along with the participant's right eye movements. We showed that in darkness and in light, horizontal gaze anticipates the orientation of the head which itself anticipates the trajectory direction. However, the horizontal angular anticipation decreases by a half in darkness for both gaze and head. In both visual conditions we observed an eye nystagmus with similar properties (frequency and amplitude). The main difference comes from the fact that in light, there is a shift of the orientations of the eye nystagmus and the head in the direction of the trajectory. These results suggest that a fundamental function of gaze is to represent self motion, stabilize the perception of space during locomotion, and to simulate the future trajectory, regardless of the vision condition. PMID:26106313
Neural Network Training by Integration of Adjoint Systems of Equations Forward in Time
NASA Technical Reports Server (NTRS)
Toomarian, Nikzad (Inventor); Barhen, Jacob (Inventor)
A method and apparatus for supervised neural learning of time dependent trajectories exploits the concepts of adjoint operators to enable computation of the gradient of an objective functional with respect to the various parameters of the network architecture in a highly efficient manner. Specifically. it combines the advantage of dramatic reductions in computational complexity inherent in adjoint methods with the ability to solve two adjoint systems of equations together forward in time. Not only is a large amount of computation and storage saved. but the handling of real-time applications becomes also possible. The invention has been applied it to two examples of representative complexity which have recently been analyzed in the open literature and demonstrated that a circular trajectory can be learned in approximately 200 iterations compared to the 12000 reported in the literature. A figure eight trajectory was achieved in under 500 iterations compared to 20000 previously required. Tbc trajectories computed using our new method are much closer to the target trajectories than was reported in previous studies.
Stable complexity and simplicial volume of manifolds
Francaviglia, Stefano; Martelli, Bruno
Let the Delta-complexity of a closed manifold M be the minimum number of simplices in a triangulation of M. Such a quantity is clearly submultiplicative with respect to finite coverings, and by taking the appropriate infimum on all finite coverings of M we can promote it to a multiplicative invariant, a characteristic number already considered by Milnor and Thurston, which we call the "stable Delta-complexity" of M. We study here the relation between the stable Delta-complexity of M and Gromov's simplicial volume ||M||. We prove that the two characteristic numbers coincide on any irreducile 3-manifold M whose JSJ decomposition consists of Seifert pieces and/or hyperbolic pieces commensurable with the figure-eight knot complement. We do not know if they coincide on any irreducible 3-manifolds with infinite fundamental group: they do if a particular three-dimensional version of the Ehrenpreis conjecture holds. On the other hand, we show that ||M|| is strictly smaller than C_n times the stable Delta-complexity o...
Migratory shearwaters integrate oceanic resources across the Pacific Ocean in an endless summer
Shaffer, Scott A.; Tremblay, Yann; Weimerskirch, Henri; Scott, Darren; Thompson, David R.; Sagar, Paul M.; Moller, Henrik; Taylor, Graeme A.; Foley, David G.; Block, Barbara A.; Costa, Daniel P.
Electronic tracking tags have revolutionized our understanding of broad-scale movements and habitat use of highly mobile marine animals, but a large gap in our knowledge still remains for a wide range of small species. Here, we report the extraordinary transequatorial postbreeding migrations of a small seabird, the sooty shearwater, obtained with miniature archival tags that log data for estimating position, dive depth, and ambient temperature. Tracks (262 ± 23 days) reveal that shearwaters fly across the entire Pacific Ocean in a figure-eight pattern while traveling 64,037 ± 9,779 km roundtrip, the longest animal migration ever recorded electronically. Each shearwater made a prolonged stopover in one of three discrete regions off Japan, Alaska, or California before returning to New Zealand through a relatively narrow corridor in the central Pacific Ocean. Transit rates as high as 910 ± 186 km·day?1 were recorded, and shearwaters accessed prey resources in both the Northern and Southern Hemisphere's most productive waters from the surface to 68.2 m depth. Our results indicate that sooty shearwaters integrate oceanic resources throughout the Pacific Basin on a yearly scale. Sooty shearwater populations today are declining, and because they operate on a global scale, they may serve as an important indicator of climate change and ocean health. PMID:16908846
Neural network training by integration of adjoint systems of equations forward in time
NASA Technical Reports Server (NTRS)
Toomarian, Nikzad (inventor); Barhen, Jacob (inventor)
A method and apparatus for supervised neural learning of time dependent trajectories exploits the concepts of adjoint operators to enable computation of the gradient of an objective functional with respect to the various parameters of the network architecture in a highly efficient manner. Specifically, it combines the advantage of dramatic reductions in computational complexity inherent in adjoint methods with the ability to solve two adjoint systems of equations together forward in time. Not only is a large amount of computation and storage saved, but the handling of real-time applications becomes also possible. The invention has been applied it to two examples of representative complexity which have recently been analyzed in the open literature and demonstrated that a circular trajectory can be learned in approximately 200 iterations compared to the 12000 reported in the literature. A figure eight trajectory was achieved in under 500 iterations compared to 20000 previously required. The trajectories computed using our new method are much closer to the target trajectories than was reported in previous studies.
An All-Optical Access Metro Interface for Hybrid WDM/TDM PON Based on OBS
NASA Astrophysics Data System (ADS)
Segarra, Josep; Sales, Vicent; Prat, Josep
A new all-optical access metro network interface based on optical burst switching (OBS) is proposed. A hybrid wavelength-division multiplexing/time-division multiplexing (WDM/TDM) access architecture with reflective optical network units (ONUs), an arrayed-waveguide-grating outside plant, and a tunable laser stack at the optical line terminal (OLT) is presented as a solution for the passive optical network. By means of OBS and a dynamic bandwidth allocation (DBA) protocol, which polls the ONUs, the available access bandwidth is managed. All the network intelligence and costly equipment is located at the OLT, where the DBA module is centrally implemented, providing quality of service (QoS). To scale this access network, an optical cross connect (OXC) is then used to attain a large number of ONUs by the same OLT. The hybrid WDM/TDM structure is also extended toward the metropolitan area network (MAN) by introducing the concept of OBS multiplexer (OBS-M). The network element OBS-M bridges the MAN and access networks by offering all-optical cross connection, wavelength conversion, and data signaling. The proposed innovative OBS-M node yields a full optical data network, interfacing access and metro with a geographically distributed access control. The resulting novel access metro architectures are nonblocking and, with an improved signaling, provide QoS, scalability, and very low latency. Finally, numerical analysis and simulations demonstrate the traffic performance of the proposed access scheme and all-optical access metro interface and architectures.
The Ecogeomorphology of Salt Pools of the Webhannet Estuary, Wells, Maine, USA
NASA Astrophysics Data System (ADS)
Wilson, K. R.; Kelley, J. T.
Salt pools are shallow, muddy depressions in salt marshes that remain flooded throughout the entire tidal cycle. They are common landforms of this ecosystem, but little is known for certain about their formation and persistence through time. Understanding the ontogeny of salt pools is critical, as it has been suggested that they may serve as important habitat for some birds and fish, and as indicators of ultimate marsh break-up and wetland loss. Hypotheses regarding pool initiation have suggested that pools are primary features of marshes, while others have suggested that pools form through secondary mechanisms such as isolated vegetative die-off or ice-plucking. Still others have suggested that pools may be associated with tidal creek abandonment. This study combines field observations, geologic coring, and analyses of a time-series of aerial photographs through geographic information systems (GIS), to quantify the recent history of pools of the Webhannet Estuary, Wells, ME, USA. Six transects sampled 119 pools during Summers 2004/2005. Adjacent percent vegetative cover (3, 1m2 plots/pool), bank classification (graded, mostly graded, mostly steep, steep), pool shape (circular, figure eight, irregular, sinuous) and a handheld GPS point were recorded. GPS data points were imported into a GIS platform to determine spatial trends. Examination of the spatial distribution suggests that pools are not randomly distributed across the marsh surface, but rather exhibit strong spatial patterns based on the pool characteristics described. Preliminary analyses of aerial photographs comparing the marsh surface in 1953 to 2003, suggest pools exhibit different developmental sequences over time (some grow, some shrink, some remain the same in area and shape). Dutch cores taken during Summer 2005 reveal a distinct pool signature and suggest that some pools may be of a more ephemeral nature than previously described and support the hypothesis that pools form through secondary mechanisms. New understanding of the development of salt pools may have practical management implications.
Movement strategies for maintaining standing balance during arm tracking in people with multiple sclerosis.
Chua, Matthew C; Hyngstrom, Allison S; Ng, Alexander V; Schmit, Brian D
The purpose of this study was to quantify hip and ankle movement strategies during a standing arm tracking task in people with multiple sclerosis (MS). Full-body kinematics and kinetics were assessed with motion analysis cameras and force plates in nine MS and nine age-matched control subjects. While standing, participants used their dominant hand to track a target moving around a large horizontal or vertical figure eight on a screen in front of them. The target moved at constant speed, or linearly increasing speeds, with a frequency between 0.05 Hz and 0.35 Hz. Hip and ankle moments and angles during tracking were calculated from kinematic and kinetic measurements. Ratios of peak-to-peak (PP) hip/ankle moments (kinetics) and angles (kinematics) were calculated to determine the strategies of the hips and ankles used to maintain balance during arm movements. Center of mass (CoM) root mean square (RMS) acceleration was calculated as a measure of overall balance performance. The MS group produced larger PP hip/ankle moments at all speeds compared with the control group (P < 0.05). The CoM RMS acceleration increased with tracking speed for both groups but was not significantly different between groups. Additionally, the ratios of hip to ankle moments were highly correlated with the Berg Balance Scale during horizontal steady-speed tracking in MS. These results suggest that people with MS increase the use of the hip during standing arm tracking compared with age-matched control subjects. This adapted strategy might allow people with MS to achieve balance performance similar to control subjects, possibly increasing the importance of the hip in maintaining balance during voluntary movements. PMID:24966303
DNA-bridging by a palindromic alpha-helix.
Suzuki, M
The nucleosomal DNA repeat of 240 base pairs in the chromatin structure of sea urchin sperm is exceptionally long and is accompanied by the presence of a histone H1 molecule larger than is usual in most species of chromatin. I propose how these two features are correlated and how they fit into the solenoidal model for the 300-A-diameter fiber of chromatin. Comparison of the sequence of spermatogenous H1 with other H1 sequences reveals an insert of 55 amino acid residues (residues 122-176). A 37-residue sequence in the insert (residues 140-176) has a palindromic character. I propose that each half of the palindromic sequence constitutes an alpha-helical DNA-binding unit and that the continuous alpha-helix made up of the two halves, by virtue of its palindromic nature, stabilizes the formation of an extra superhelical turn by the long linker DNA between two nucleosome cores. The N-terminal-C-terminal "polarity" of each alpha-helical section of half the palindromic sequence indicates how the arginine/lysine-rich DNA-binding surface of the alpha-helical section is used. The polarity of the H1 insertion sequence supports the so-called "reverse-loop" model or a "figure-eight" model for the path of the DNA within the solenoid structure; i.e., the linker DNA forms a right-handed superhelical turn toward the center of the solenoid structure. This use of a pair of a palindromically related alpha-helical sections has a similarity with the "scissors-grip" model for the interaction of the leucine-zipper proteins with DNA. Images PMID:1528886
Analysis of the Radial and Longitudinal Effect in a Double TE 104 and a Single TE 102 Rectangular Cavity
NASA Astrophysics Data System (ADS)
Mazúr, Milan; Valko, Marián; Morris, Harry
The response of the cavity to the rotation of a pointlike sample in the horizontal ( y- z) plane passing through the center of the Bruker double TE 104 and single TE 102 rectangular cavities in concentric circles of radii ? = 0, 1, 2, 3, 4, and 5 mm from the cavity center (radial effect) has been analyzed. The experimentally observed dependencies of the EPR signal intensity, Ipp, showed the following: (i) for ? = 0 mm (a sample position in the cavity center), Ipp is independent of the angle of rotation; (ii) for ? = 1, 2, and 3 mm, the Ipp dependence progressively changes from circular to oval; (iii) when the radius is further increased to ? = 4 and 5 mm, the Ipp dependence changes dramatically, giving a figure eight shape. These experimental observations are in very good agreement with the theoretical calculations, in which the response is modeled using modified Cassinian curves, K(?, ?). Similar trends were observed for any position of the horizontal ( y- z) plane at which the sample is situated along the vertical x axis of the cavity; however, the amplitude of the signal decreases with increase in the absolute value of the x coordinate, ? x?. The variation in the signal amplitude along the cavity x axis (longitudinal effect) can be calculated theoretically using a modified sine-squared curve, G( x). In general, the response of the cavity to a pointlike sample situated at any position, P(?, ?, x), can be represented as a product of the mentioned Cassinian curve, K(?, ?), and sine-squared curve, G( x), giving for the signal intensity Ipp(?, ?, x) ? K(?, ?) G( x). The response to a large cylindrical sample which is concentrically situated on the cavity x axis can then be obtained by integrating the above product, K(?, ?) G( x), over the sample volume. The nonlinear radial effect may give rise to a serious source of systematic error in quantitative EPR spectroscopy and shows that accurate and precise positioning of the sample in the microwave cavity is essential.
Activation times in and adjacent to reentry circuits during entrainment: implications for mapping ventricular tachycardia.
Khan, H H; Stevenson, W G
Myocardial infarct scars giving rise to reentrant ventricular tachycardia can contain "bystander" areas of abnormal electrical activity that are difficult to distinguish from reentry circuit sites. Pacing to entrain ventricular tachycardia with analysis of electrograms at the pacing site is useful to identify reentry circuit sites but assumes that electrograms reflect activation times at the recording site. The purpose of this study was to determine whether a similar analysis could be applied to electrograms recorded from sites distant from the pacing site. In computer simulations, activation times at sites in and adjacent to figure-eight reentry circuits were analyzed during entrainment of tachycardia by pacing at various sites. During entrainment, activation at reentry circuit sites activated by the stimulated orthodromic wavefronts maintains the same relation to the QRS complex as that during tachycardia. The return cycle from the last entrained electrogram to the following electrogram equals the tachycardia cycle length. The same findings occur, however, at bystander sites activated by stimulated wavefronts that have propagated orthodromically through the circuit. When a reentry circuit site is activated by stimulated antidromic wavefronts, the electrogram to QRS interval is shorter than that during tachycardia, the return cycle may be less than the tachycardia cycle length, and the site may appear to be dissociated from the tachycardia, despite its location in the circuit. If the entrained electrogram to QRS interval exceeds the tachycardia electrogram to QRS interval and the return cycle length exceeds the tachycardia cycle length, it is likely that both pacing and recording sites are outside the reentry circuit. Thus, during entrainment, failure to dissociate an electrogram from the QRS complex and the return cycle length does not reliably indicate the relation of the recording site to the reentry circuit when the recording and pacing sites are separate. PMID:8154421
Physiological modules for generating discrete and rhythmic movements: action identification by a dynamic recurrent neural network.
Bengoetxea, Ana; Leurs, Françoise; Hoellinger, Thomas; Cebolla, Ana M; Dan, Bernard; McIntyre, Joseph; Cheron, Guy
In this study we employed a dynamic recurrent neural network (DRNN) in a novel fashion to reveal characteristics of control modules underlying the generation of muscle activations when drawing figures with the outstretched arm. We asked healthy human subjects to perform four different figure-eight movements in each of two workspaces (frontal plane and sagittal plane). We then trained a DRNN to predict the movement of the wrist from information in the EMG signals from seven different muscles. We trained different instances of the same network on a single movement direction, on all four movement directions in a single movement plane, or on all eight possible movement patterns and looked at the ability of the DRNN to generalize and predict movements for trials that were not included in the training set. Within a single movement plane, a DRNN trained on one movement direction was not able to predict movements of the hand for trials in the other three directions, but a DRNN trained simultaneously on all four movement directions could generalize across movement directions within the same plane. Similarly, the DRNN was able to reproduce the kinematics of the hand for both movement planes, but only if it was trained on examples performed in each one. As we will discuss, these results indicate that there are important dynamical constraints on the mapping of EMG to hand movement that depend on both the time sequence of the movement and on the anatomical constraints of the musculoskeletal system. In a second step, we injected EMG signals constructed from different synergies derived by the PCA in order to identify the mechanical significance of each of these components. From these results, one can surmise that discrete-rhythmic movements may be constructed from three different fundamental modules, one regulating the co-activation of all muscles over the time span of the movement and two others elliciting patterns of reciprocal activation operating in orthogonal directions. PMID:25278868
The tachykinin NK3 receptor antagonist SR142801 blocks the behavioral effects of cocaine in marmoset monkeys.
De Souza Silva, Maria A; Mello, Eldon L; Müller, Christian P; Jocham, Gerhard; Maior, Rafael S; Huston, Joseph P; Tomaz, Carlos; Barros, Marilia
Brain neuropeptide transmitters of the tachykinin family are involved in the organization of many behaviors. However, little is known about their contribution to the behavioral effects of drugs of abuse. Recently, the tachykinin NK3 receptor, one of the three tachykinin receptors in the brain, was shown to attenuate the acute and chronic behavioral effects of cocaine in rats. In order to test if these findings can be generalized to primates we investigated the role of the tachykinin NK3 receptor in the acute behavioral effects of cocaine in marmoset monkeys (Callithrix penicillata) using a figure-eight maze procedure. Animals were pretreated with the tachykinin NK3 receptor antagonist, (R)-(N)-[1-[3-[1-benzoyl-3-(3,4-dichlorophenyl)piperidin-3-yl]propyl]-4-phenylpiperidin-4-yl]-N-methylacetamide (SR142801; 0, 0.02, 0.2, 2.0 mg/kg, i.p.), and received either a treatment with cocaine (10 mg/kg, i.p) or saline (i.p.). Cocaine increased locomotor activity and aerial glance behavior, but reduced exploratory and bodycare activities, scent marking and terrestrial scanning behavior. A sensitivity analysis revealed that two responder types can be differentiated in relation to the occurrence of a hyperlocomotor response to cocaine. SR142801 blocked the actions of cocaine on several behaviors dose-dependently for each responder type, respectively. There was no effect of SR142801 alone on any behavior measured. These data suggest that the tachykinin NK3 receptor contributes to the individual behavioral response to cocaine in marmoset monkeys. Having no behavioral effects on its own, but blocking the cocaine effects, might suggest the tachykinin NK3 receptor antagonist, SR142801, as a potential treatment of cocaine addiction in humans. PMID:16603151
Physiological modules for generating discrete and rhythmic movements: action identification by a dynamic recurrent neural network
Bengoetxea, Ana; Leurs, Françoise; Hoellinger, Thomas; Cebolla, Ana M.; Dan, Bernard; McIntyre, Joseph; Cheron, Guy
In this study we employed a dynamic recurrent neural network (DRNN) in a novel fashion to reveal characteristics of control modules underlying the generation of muscle activations when drawing figures with the outstretched arm. We asked healthy human subjects to perform four different figure-eight movements in each of two workspaces (frontal plane and sagittal plane). We then trained a DRNN to predict the movement of the wrist from information in the EMG signals from seven different muscles. We trained different instances of the same network on a single movement direction, on all four movement directions in a single movement plane, or on all eight possible movement patterns and looked at the ability of the DRNN to generalize and predict movements for trials that were not included in the training set. Within a single movement plane, a DRNN trained on one movement direction was not able to predict movements of the hand for trials in the other three directions, but a DRNN trained simultaneously on all four movement directions could generalize across movement directions within the same plane. Similarly, the DRNN was able to reproduce the kinematics of the hand for both movement planes, but only if it was trained on examples performed in each one. As we will discuss, these results indicate that there are important dynamical constraints on the mapping of EMG to hand movement that depend on both the time sequence of the movement and on the anatomical constraints of the musculoskeletal system. In a second step, we injected EMG signals constructed from different synergies derived by the PCA in order to identify the mechanical significance of each of these components. From these results, one can surmise that discrete-rhythmic movements may be constructed from three different fundamental modules, one regulating the co-activation of all muscles over the time span of the movement and two others elliciting patterns of reciprocal activation operating in orthogonal directions. PMID:25278868
Coordination of gaze and hand movements for tracking and tracing in 3D.
Gielen, Constantinus C A M; Dijkstra, Tjeerd M H; Roozen, Irene J; Welten, Joke
In this study we have investigated movements in three-dimensional space. Since most studies have investigated planar movements (like ellipses, cloverleaf shapes and "figure eights") we have compared two generalizations of the two-thirds power law to three dimensions. In particular we have tested whether the two-thirds power law could be best described by tangential velocity and curvature in a plane (compatible with the idea of planar segmentation) or whether tangential velocity and curvature should be calculated in three dimensions. We defined total curvature in three dimensions as the square root of the sum of curvature squared and torsion squared. The results demonstrate that most of the variance is explained by tangential velocity and total curvature. This indicates that all three orthogonal components of movements in 3D are equally important and that movements are truly 3D and do not reflect a concatenation of 2D planar movement segments. In addition, we have studied the coordination of eye and hand movements in 3D by measuring binocular eye movements while subjects move the finger along a curved path. The results show that the directional component and finger position almost superimpose when subjects track a target moving in 3D. However, the vergence component of gaze leads finger position by about 250msec. For drawing (tracing) the path of a visible 3D shape, the directional component of gaze leads finger position by about 225msec, and the vergence component leads finger position by about 400msec. These results are compatible with the idea that gaze leads hand position during drawing movement to assist prediction and planning of hand position in 3D space. PMID:18718579
Full vector spherical harmonic analysis of the Holocene geomagnetic field
NASA Astrophysics Data System (ADS)
Richardson, Marcia
High-quality time-series paleomagnetic measurements have been used to derive spherical harmonic models of Earth's magnetic field for the past 2,000 years. A newly-developed data compilation, PSVMOD2.0 consists of time-series directional and intensity records that significantly improve the data quality and global distribution used to develop previous spherical harmonic models. PSVMOD2.0 consists of 185 paleomagnetic time series records from 85 global sites, including 30 full-vector records (inclination, declination and intensity). It includes data from additional sites in the Southern Hemisphere and Arctic and includes globally distributed sediment relative paleointensity records, significantly improving global coverage over previous models. PSVMOD2.0 records have been assessed in a series of 7 regional intercomparison studies, four in the Northern Hemisphere and 3 in the southern hemisphere. Comparisons on a regional basis have improved the quality and chronology of the data and allowed investigation of spatial coherence and the scale length associated with paleomagnetic secular variation (PSV) features. We have developed a modeling methodology based on nonlinear inversion of the PSVMOD2.0 directional and intensity records. Models of the geomagnetic field in 100-year snapshots have been derived for the past 2,000 with the ultimate goal of developing models spanning the past 8,000 years. We validate the models and the methodology by comparing with the GUFM1 historical models during the 400-year period of overlap. We find that the spatial distribution of sites and quality of data are sufficient to derive models that agree with GUFM1 in the large-scale characteristics of the field. We use the the models derived in this study to downward continue the field to the core-mantle boundary and examine characteristics of the large-scale structure of the magnetic field at the source region. The derived models are temporally consistent from one epoch to the next and exhibit many of the expected characteristics of the field over time (high-latitude flux lobes, South Atlantic reverse flux patch, north pole reverse or null flux region).
Distributed Algorithm for Signal Polarity Adjustment of Air-Conditioner Control Network
NASA Astrophysics Data System (ADS)
Ninagawa, Chuzo; Aoi, Fumio; Yokohama, Koji; Yoneda, Tomohiro
This paper proposes a distributed algorithm for adjusting the signal polarity of the control networks for building air-conditioners. As field connection work of the two wires to the controller may be straight or cross, each controller has both plus and minus polarity circuits. It starts the algorithm in the arbitary sequence, and then negociates each other to select the plus/minus polarity circuits in order to adjust the signal polarity. A Time Petri Net model was constructed for verification of the proposed algorithm. The model describes the required specification of the system, straight/cross connection of the controller to the network bus line and the polarity adjustment algorithm. The efficient Time Petri Net verification tool made it possible to verify the model.
A system framework for information assurance in AONs
NASA Astrophysics Data System (ADS)
Wang, Jiang-ping; Zhou, Sheng-jun; Li, Yuquan
All-optical Networks (AONs) are unique in that they support many optical wavelengths , which use optical amplifiers, optical add/drop multiplexers and optical switches or cross-connects. They contain only optical components and are intrinsically different from optical networks currently being used. Note that many of the security problems present in traditional electronic or electro-optic networks are still to be found in AONs. Moreover, for AONs"s service disruption is most easily achieved in optical amplifies, while the tapping or eavesdropping is most easily achieved through nonlinearities in transmission fiber. These types of attacks on AON will thwart data security. In order to assure information in AONs which have a minimum privacy and quality of service (QoS), this paper presents an analysis of attacks in AONs and propose a conceptual system framework for information assurance in AONs.
Fbis report. Science and technology: China, October 18, 1995
;Partial Contents: Nanomaterials Fabrication, Applications Research Advances Noted; CAST Announces World`s First Space-Grown Large-Diameter GaAs Monocrystal; Assay of Antiviral Activity of Antisense Phosphorothioate Oligodeoxynucleotide Against Dengue Virus; Expression and Antigenicity of Chimeric Proteins of Cholera Toxin B Subunit With Hepatitis C Virus; CNCOFIEC Signs Agreement With IBM for New Intelligent Building; Latest Reports on Optical Computing, Memory; BIDC To Introduce S3 Company`s Multimedia Accelerator Chipset; Virtual Private PCN Ring Network Based on ATM VP Cross-Connection; Beijing Gets Nation`s First Frame Relay Network; Situation of Power Industry Development and International Cooperation; Diagrams of China`s Nuclear Waste Containment Vessels; Chinese-Developed Containment Vessel Material Reaches World Standards; Second Fuel Elements for Qinshan Plant Passes Inspection; and Geothermal Deep-Well Electric Pump Technology Developed.
Waveband switching in light trail optical networks with dynamic traffic [Invited
NASA Astrophysics Data System (ADS)
Ye, Yabin; Woesner, Hagen; Chlamtac, Imrich
Wavelength switching is used in current light-path networks to set up connections between node pairs. With the increase in the number of wavelengths per fiber, waveband switching has been proposed for decreasing the number of switching ports in optical nodes. Another concept called a 'light trail' allows the intermediate nodes along a light path to access the wavelength channel, aiming at the reduction of the total number of wavelengths. Both techniques apply traffic grooming on different levels of a WDM network. We combine and compare these two switching techniques: waveband switching light path (WBS-LP) and waveband switching light trail (WBS-LT). For both WBS-LP and WBS-LT networks, auxiliary graph models are proposed to exploit not only the wavelength resources in the fiber links but also the limited waveband port resources inside multigranular optical cross connect (MG-OXC) nodes.
Electrothermally actuated tip-tilt-piston micromirror with integrated varifocal capability.
Morrison, Jessica; Imboden, Matthias; Little, Thomas D C; Bishop, D J
MEMS micromirrors have proven to be very important optical devices with applications ranging from steerable mirrors for switches and cross-connects to spatial light modulators for correcting optical distortions. Usually beam steering and focusing are done with different MEMS devices and tilt angles in excess of 10 degrees are seldom obtained. Here we describe a single MEMS device that combines tip/tilt, piston mode and varifocal capability into a single, low cost device with very large tilt angles. Our device consists of a 400 micron diameter mirror driven with thermal bimorphs. We have demonstrated deflection angles of ± 40 degrees along both axes, a tunable focal length which varies between -0.48 mm to + 20.5 mm and a piston mode range of 300 microns - four separately controllable degrees of freedom in a single device. Potential applications range from smart lighting to optical switches and devices for telecom systems. PMID:25968784
Modulation of amplitude and latency of motor evoked potential by direction of transcranial magnetic stimulation
NASA Astrophysics Data System (ADS)
Sato, Aya; Torii, Tetsuya; Iwahashi, Masakuni; Itoh, Yuji; Iramina, Keiji
The present study analyzed the effects of monophasic magnetic stimulation to the motor cortex. The effects of magnetic stimulation were evaluated by analyzing the motor evoked potentials (MEPs). The amplitude and latency of MEPs on the abductor pollicis brevis muscle were used to evaluate the effects of repetitive magnetic stimulation. A figure eight-shaped flat coil was used to stimulate the region over the primary motor cortex. The intensity of magnetic stimulation was 120% of the resting motor threshold, and the frequency of magnetic stimulation was 0.1 Hz. In addition, the direction of the current in the brain was posterior-anterior (PA) or anterior-posterior (AP). The latency of MEP was compared with PA and AP on initial magnetic stimulation. The results demonstrated that a stimulus in the AP direction increased the latency of the MEP by approximately 2.5 ms. MEP amplitude was also compared with PA and AP during 60 magnetic stimulations. The results showed that a stimulus in the PA direction gradually increased the amplitude of the MEP. However, a stimulus in the AP direction did not modulate the MEP amplitude. The average MEP amplitude induced from every 10 magnetic pulses was normalized by the average amplitude of the first 10 stimuli. These results demonstrated that the normalized MEP amplitude increased up to approximately 150%. In terms of pyramidal neuron indirect waves (I waves), magnetic stimulation inducing current flowing backward to the anterior preferentially elicited an I1 wave, and current flowing forward to the posterior elicited an I3 wave. It has been reported that the latency of the I3 wave is approximately 2.5 ms longer than the I1 wave elicitation, so the resulting difference in latency may be caused by this phenomenon. It has also been reported that there is no alteration of MEP amplitude at a frequency of 0.1 Hz. However, this study suggested that the modulation of MEP amplitude depends on stimulation strength and stimulation direction.
Design and Implementation of a RF Powering Circuit for RFID Tags or Other Batteryless Embedded Devices
Liu, Dongsheng; Wang, Rencai; Yao, Ke; Zou, Xuecheng; Guo, Liang
A RF powering circuit used in radio-frequency identification (RFID) tags and other batteryless embedded devices is presented in this paper. The RF powering circuit harvests energy from electromagnetic waves and converts the RF energy to a stable voltage source. Analysis of a NMOS gate-cross connected bridge rectifier is conducted to demonstrate relationship between device sizes and power conversion efficiency (PCE) of the rectifier. A rectifier with 38.54% PCE under normal working conditions is designed. Moreover, a stable voltage regulator with a temperature and voltage optimizing strategy including adoption of a combination resistor is developed, which is able to accommodate a large input range of 4 V to 12 V and be immune to temperature variations. Latch-up prevention and noise isolation methods in layout design are also presented. Designed with the HJTC 0.25 ?m process, this regulator achieves 0.04 mV/°C temperature rejection ratio (TRR) and 2.5 mV/V voltage rejection ratio (VRR). The RF powering circuit is also fabricated in the HJTC 0.25 ?m process. The area of the RF powering circuit is 0.23 × 0.24 mm2. The RF powering circuit is successfully integrated with ISO/IEC 15693-compatible and ISO/IEC 14443-compatible RFID tag chips. PMID:25123466
Pressure-driven ballistic Kelvin's water dropper for energy harvesting.
Xie, Yanbo; de Boer, Hans L; Sprenkels, Ad J; van den Berg, Albert; Eijkel, Jan C T
In this paper, we introduce a microfluidic-based self-excited energy conversion system inspired by Kelvin's water dropper but driven by inertia instead of gravity. Two micro water jets are produced by forcing water through two micropores by overpressure. The jets break up into microdroplets which are inductively charged by electrostatic gates. The droplets land on metal targets which are gradually charged up to high voltages. Targets and electrostatic gates are cross-connected in a way similar to Kelvin's water dropper. Application of pressure as driving force instead of gravity as in Kelvin's dropper allows for much higher energy densities. To prevent overcharging of the droplets by the inductive mechanism and consequent droplet loss by repulsion from the target as in Kelvin's water dropper, a voltage divider using inversely connected diodes was introduced in our system to control the charge induction providing self-limiting positive feedback by the diode characteristics. A maximal 18% energy conversion efficiency was obtained with the diode-gated system. PMID:25112848
"Stop Ne(c)king around": How interactomics contributes to functionally characterize Nek family kinases
Meirelles, Gabriela Vaz; Perez, Arina Marina; de Souza, Edmárcia Elisa; Basei, Fernanda Luisa; Papa, Priscila Ferreira; Melo Hanchuk, Talita Diniz; Cardoso, Vanessa Bomfim; Kobarg, Jörg
Aside from Polo and Aurora, a third but less studied kinase family involved in mitosis regulation is the never in mitosis-gene A (NIMA)-related kinases (Neks). The founding member of this family is the sole member NIMA of Aspergillus nidulans, which is crucial for the initiation of mitosis in that organism. All 11 human Neks have been functionally assigned to one of the three core functions established for this family in mammals: (1) centrioles/mitosis; (2) primary ciliary function/ciliopathies; and (3) DNA damage response (DDR). Recent findings, especially on Nek 1 and 8, showed however, that several Neks participate in parallel in at least two of these contexts: primary ciliary function and DDR. In the core section of this in-depth review, we report the current detailed functional knowledge on each of the 11 Neks. In the discussion, we return to the cross-connections among Neks and point out how our and other groups' functional and interactomics studies revealed that most Neks interact with protein partners associated with two if not all three of the functional contexts. We then raise the hypothesis that Neks may be the connecting regulatory elements that allow the cell to fine tune and synchronize the cellular events associated with these three core functions. The new and exciting findings on the Nek family open new perspectives and should allow the Neks to finally claim the attention they deserve in the field of kinases and cell cycle biology. PMID:24921005
Assessment of domestic water quality: case study, Beirut, Lebanon.
Korfali, Samira Ibrahim; Jurdi, Mey
In urban cities, the environmental services are the responsibility of the public sector, where piped water supply is the norm for urban household. Likewise, in Beirut City (capital of Lebanon) official water authorities are the main supplier of domestic water through a network of piping system that leaks in many areas. Beirut City and its suburbs are overpopulated since it is the residence of 1/3 of the Lebanese citizens. Thus, Beirut suffers deficiency in meeting its water demand. Water rationing, as a remedial action, is firmly established since four decades by the Lebanese Water Authorities. Consumers resorted then to private wells to supplement their domestic water needs. Consequently, household water quality is influenced by external factors relating to well water characteristics and internal factors depending on the types of the pipes of the distribution network and cross connections to sewer pipes. These factors could result in chemical and microbial contamination of drinking water. The objective of this study is to investigate domestic water quality variation in Beirut City emerging form the aforementioned factors. The presented work encircles a typical case study of Beirut City (Ras Beirut). Results showed deterioration pattern in domestic water quality. The predicted metal species and scales within the water pipes of distribution network depended on water pH, hardness, sulfate, chloride, and iron. The corrosion of iron pipes mainly depended on Mg hardness. PMID:17380419
Unfolded protein response in filamentous fungi-implications in biotechnology.
Heimel, Kai
The unfolded protein response (UPR) represents a mechanism to preserve endoplasmic reticulum (ER) homeostasis that is conserved in eukaryotes. ER stress caused by the accumulation of potentially toxic un- or misfolded proteins in the ER triggers UPR activation and the induction of genes important for protein folding in the ER, ER expansion, and transport from and to the ER. Along with this adaptation, the overall capacity for protein secretion is markedly increased by the UPR. In filamentous fungi, various approaches to employ the UPR for improved production of homologous and heterologous proteins have been investigated. As the effects on protein production were strongly dependent on the expressed protein, generally applicable strategies have to be developed. A combination of transcriptomic approaches monitoring secretion stress and basic research on the UPR mechanism provided novel and important insight into the complex regulatory cross-connections between UPR signalling, cellular physiology, and developmental processes. It will be discussed how this increasing knowledge on the UPR might stimulate the development of novel strategies for using the UPR as a tool in biotechnology. PMID:25384707
Contamination of stormwater by wastewater: a review of detection methods.
Panasiuk, Oleksandr; Hedström, Annelie; Marsalek, Jiri; Ashley, Richard M; Viklander, Maria
Even in separate sewer systems, wastewater may find its way into the receiving waters through stormwater sewers. The main reasons for this are cross-connections, illicit connections, overflows and leakages through broken sewers. Such discharges may affect receiving water quality and increase risks to public health and aquatic organisms. Detecting wastewater contamination and locating its points of ingress into storm sewer systems can be a challenging task, which should be addressed using proper methods and indicator parameters. A number of detection methods have already been proposed in this area, yet there is a lack of a general overview of such methods. This literature review summarizes and evaluates the methods used for detecting wastewater in stormwater, including those recently developed. The advantages, weaknesses and limitations of individual methods are discussed. It is concluded that while no single method can as yet produce results in a precise, fast and inexpensive way, the use of human waste specific chemical and microbiological markers, and their innovative sampling, offer the way forward. Guidance for selecting the most effective combinations of detection methods, under specific conditions, is also provided. PMID:25662485
Fission products behavior in molten fluoride salts: Speciation of La3+ and Cs+ in melts containing oxide ions
NASA Astrophysics Data System (ADS)
Rollet, Anne-Laure; Veron, Emmanuel; Bessada, Catherine
In this paper we address the effects of fission products on the speciation in molten fluoride salts. Numerous systems with cross-connections have been investigated in order to better identify the influence of CsF in a fluoride melt containing rare earth and oxides : LaF3-AF (A = Li, Na, K, Rb and Cs), LaF3-LiF-CsF, LaF3-LiF-CaF2, LaF3-LiF-CaO, LaF3-LiF-CaO-CsF. In this goal, we performed high temperature NMR experiments and followed in situ the evolution of 19F, 23Na, 85Rb, 133Cs and 139La NMR chemical shifts. In LaF3-AF-CsF and LaF3-AF-CaF2 systems, the coordination number of lanthanum cation ranges from 6 to 8 depending on the LaF3 concentration and on the polarizability of the other cations. The addition of oxide (CaO) in the latter mixtures leads to the formation of lanthanum oxyfluoride species that precipitate in LaOF when CaO concentration is increased. The addition of CsF to LaF3-LiF-CaO yields to a displacement of the dissolved versus precipitated LaOF proportion.
Single-chip 1×84 MEMS mirror array for optical telecommunication applications
NASA Astrophysics Data System (ADS)
Juneau, Thor N.; Chen, Tony; Brosnihan, Tim; Rajaraman, Swaminathan; Chau, Kevin H.; Judy, Michael
The inherent ability of silicon micromachining to provide a multitude of precision aligned optical components on a single die naturally facilitates optical communication trends towards installing larger cross-connects and transmitting many channels on individual fibers. A micromachined mirror array has been designed and fabricated using the Analog Devices, Inc. (ADI) Optical iMEMS (R) process. The single-chip mirror die consists of 84 mirrors arranged in a linear array with an average pitch of 95 ?m. Each mirror is equipped with a pair of polysilicon actuation electrodes located beneath the mirror. These two electrodes allow each mirror to be independently rotated around the axis parallel to the long dimension of the array using off-chip voltage commands. An operating mirror tilt of +/- 2 degrees is achieved with less than 130 volts of actuation. The design objectives including high mirror fill factor, optimal air damping, low mirror-to-mirror cross talk, acceptable voltage levels, and robustness posed significant challenges. This paper will describe how these challenges were overcome using an interdigitated mirror layout. The mirrors were successfully fabricated with good yield and characterized through both customer and ADI testing.
Optical switch based on thermocapillarity
NASA Astrophysics Data System (ADS)
Sakata, Tomomi; Makihara, Mitsuhiro; Togo, Hiroyoshi; Shimokawa, Fusao; Kaneko, Kazumasa
Space-division optical switches are essential for the protection, optical cross-connects (OXCs), and optical add/drop multiplexers (OADMs) needed in future fiber-optic communication networks. For applications in these areas, we proposed a thermocapillarity switch called oil-latching interfacial-tension variation effect (OLIVE) switch. An OLIVE switch is a micro-mechanical optical switch fabricated on planar lightwave circuits (PLC) using micro-electro-mechanical systems (MEMS) technology. It consists of a crossing waveguide that has a groove at each crossing point and a pair of microheaters. The groove is partially filled with the refractive-index-matching liquid, and optical signals are switched according to the liquid's position in the groove, i.e., whether it is passing straight through the groove or reflecting at the sidewall of the groove. The liquid is driven by thermocapillarity and latched by capillarity. Using the total internal reflection to switch the optical path, the OLIVE switch exhibits excellent optical characteristics, such as high transparency (insertion loss: < 2 dB), high extinction ratio (> 50 dB), and low crosstalk (< -50 dB). Moreover, since this switch has a simple structure and bi-stability, it has wide variety of applications in wavelength division multiplexing (WDM) networks.
Real-time monitoring of river water quality using in-line continuous acquisition of fluorescence excitation and emission matrices
NASA Astrophysics Data System (ADS)
Carstea, E.; Baker, A.; Johnson, R.; Reynolds, D. M.
In-line fluorescence EEM monitoring has been performed over an eleven-day period for Bournbrook River, Birmingham, UK. River water was diverted to a portable laboratory via a continuous flow pump and filter system. Fluorescence excitation-emission matrices data was recorded every 3 minutes using a flow cell (1cm pathlength) coupled to a fiber optic probe. This real-time fluorescence EEM data (Excitation, 225-400 nm at 5 nm steps, emission, 280-500 nm at 2 nm steps) was collected 'in-line'and directly compared with the spectrophotometric properties and physical and chemical parameters of river water samples collected off-line at known time intervals. Over the monitoring period, minor pollution pulses from cross connections were detected and identified hourly along with a random diesel pollution event. This work addresses the practicalities of measuring and detecting fluorescence EEM in the field and discusses the potential of this technological approach for further understanding important hydrological and biogeochemical processes. Problems associated with fouling and system failure are also reported. Example of the data generated from the continuous fluorescence EEM monitoring.
Greywater recycling systems in Germany--results, experiences and guidelines.
Nolde, E
Although Germany is not considered a water-poor country, there exist regional differences in water supply and consumption. During the past 15 years, the greywater aspect has been dealt with in Germany with a greater interest and variable success. In addition to an increased environmental awareness, water costs also play an important role in increasing the demand for advanced greywater treatment plants nstalled in buildings. Under favourable conditions, the amortisation costs usually lie between 5 and 7 years. Systems that have been extensively tried and tested and have been shown to be most reliable are those employing an advanced biological treatment followed by an UV disinfection. Systems based on membrane technology are being developed and researched intensively in Germany for municipal wastewater treatment. However, so far they play no role in greywater recycling. Greywater systems operating under low energy and maintenance requirements without the use of chemicals are mostly favoured. In Germany, greywater recycling systems should be registered at the Health Office in order to guarantee that no cross-connections exist with the drinking water network and that pipes are labelled according to regulations. The hygienic requirements for recycled greywater, which is primarily used for toilet flushing, are oriented towards the EU-Guidelines for Bathing Waters. The use of recycled greywater for irrigation purposes is minor. As to the use of recycled water for laundry, the first promising investigation results are now available. PMID:16104423
Flexible and simple link design for long-haul transmission taking real span-length variations into account
NASA Astrophysics Data System (ADS)
Breuer, Dirk; Hanik, Norbert
The pressure on prices per bit and distance in operator networks requires an ongoing reduction of costs. In todays optical transport networks typical transparent transmission lengths are in the order of about 400 to 600 km. Then costly electrical 3R-regeneration is required. One way to deal with this cost-driver is to introduce ultra long haul (ULH) transparent WDM systems which are able to cover transmission length of e.g. up to 2000 km and thus decreasing the number of regenerative transponders. However, to maintain the flexibility of the network to add and drop traffic at required locations the use of optical add drop multiplexers (OADMs) or optical cross connects (OXCs) is mandatory in these systems, particularly for pan-European but even for European national networks. The design of such ULH-networks has to deal with a vast number of issues, in particular the physical layer design has to be very flexible and to allow for different optimization and adjustment schemes. In this paper based on computer simulations we will compare different approaches to reduce the design complexity of 10 Gbit/s ULH systems taking into account environmental constraints like availability of housing stations for different target distances.
Micro-actuator with extended analog deflection at low drive voltage
NASA Astrophysics Data System (ADS)
Dürr, Peter; Gehner, Andreas; Schmidt, Jan; Kunze, Detlef; Wagner, Michael; Lakner, Hubert
Electrostatic Micro-actuators are being increasingly used for a wide variety of applications such as spatial light modulators, scanning mirrors, optical cross connects, micro-valves, and others. Usually the electrical forces operate in one direction and are balanced by a mechanical spring. The resulting deflection is then either defined by a mechanical stop, or it is only a meta-stable equilibrium position: at an additional external force or deflection it will snap to a different position, frequently again defined by a mechanical stop. This issue is well known and is often called 'pull-in'. In the often used parallel-plate capacitor actuator, the instability already begins at a deflection of only on third of the original capacitor plate separation. For safety reasons and due to the steep response-curve one can only use an even smaller fraction of the mechanically possible movement. This means, that the gap below the actuator has to be designed very much larger than the required maximum deflection. To get the pre-described force and deflection, a much higher voltage is needed than for potential smaller gap widths. The useable range of deflection for many types of micro-actuators can be extended without the penalty of large drive voltage or low shock resistivity, by employing springs with steeper-than-linear restoring force. Alternatively, the voltage needed for a given range of deflection may be reduced. This paper shows the benefits and how to design and dimension these types of springs.
Microbial health risks associated with exposure to stormwater in a water plaza.
Sales-Ortells, Helena; Medema, Gertjan
Climate change scenarios predict an increase of intense rainfall events in summer in Western Europe. Current urban drainage systems cannot cope with such intense precipitation events. Cities are constructing stormwater storage facilities to prevent pluvial flooding. Combining storage with other functions, such as recreation, may lead to exposure to contaminants. This study assessed the microbial quality of rainwater collected in a water plaza and the health risks associated with recreational exposure. The water plaza collects street run-off, diverges first flush to the sewer system and stores the rest of the run-off in the plaza as open water. Campylobacter, Cryptosporidium and Legionella pneumophila were the pathogens investigated. Microbial source tracking tools were used to determine the origin (human, animal) of the intestinal pathogens. Cryptosporidium was not found in any sample. Campylobacter was found in all samples, with higher concentrations in samples containing human Bacteroides than in samples with zoonotic contamination (15 vs 3.7 gc (genomic copies)/100 mL). In both cases, the estimated disease risk associated with Campylobacter and recreational exposure was higher than the Dutch national incidence. This indicates that the health risk associated with recreational exposure to the water plaza is significant. L. pneumophila was found only in two out of ten pond samples. Legionnaire's disease risks were lower than the Dutch national incidence. Presence of human Bacteroides indicates possible cross-connections with the CSS that should be identified and removed. PMID:25706222
Broadband local service offerings using free-space optical links: a network business perspective
NASA Astrophysics Data System (ADS)
Britz, David M.; Dodley, J. P.; Barnickel, D. J.
12 This paper describes a promising optical wireless broadband technology that will provide low cost broadband services to the local access `last mile' market. This paper examines the application, advantages and limitations of utilizing Free Space Optical Communications (FSOC) systems for broadband access markets. The service markets that would fully utilize FSOC technologies include metropolitan areas, BLECs (multi- tenant dwellings/business apartments), campuses, industrial parks and `pole-to-hole' neighborhood deployments. This paper will identify weather dependent link availability as being the primary consideration in defining and selecting suitable locations for FSOC-based systems. Link availability in turn determines link range, type of service, and the need for transmission diversity. This paper will describe the implications of telecom `five nines' last-mile access availability and its effect on the transparent integration of FSOC technologies into the existing fiber optic networks. This paper will also describe propagation losses and link budget requirements for broadband FSOC-based local service. During adverse weather conditions, stand-alone, FSOC-based optical wireless links typically offer path lengths of less than 200 meters while still meeting the `five nines' availability criteria. This paper will also consider `availability limited' services. These services may prove to be attractive to customers who are willing to accept broadband service on an `as available basis'. The use of availability-enhancing transmission diversity and the use of intelligent `roof-top' routing and optical wireless cross connects between buildings will also be discussed.
Human enteric viruses in groundwater from a confined bedrock aquifer
Borchardt, M. A.; Bradbury, K.R.; Gotkowitz, M.B.; Cherry, J.A.; Parker, B.L.
Confined aquifers are overlain by low-permeability aquitards that are commonly assumed to protect underlying aquifers from microbial contaminants. However, empirical data on microbial contamination beneath aquitards is limited. This study determined the occurrence of human pathogenic viruses in well water from a deep sandstone aquifer confined by a regionally extensive shale aquitard. Three public water-supply wells were each sampled 10 times over 15 months. Samples were analyzed by reverse transcription-polymerase chain reaction (RT-PCR) for several virus groups and by cell culture for infectious enteroviruses. Seven of 30 samples were positive by RT-PCR for enteroviruses; one of these was positive for infectious echovirus 18. The virus-positive samples were collected from two wells cased through the aquitard, indicating the viruses were present in the confined aquifer. Samples from the same wells showed atmospheric tritium, indicating water recharged within the past few decades. Hydrogeologic conditions support rapid porous media transport of viruses through the upper sandstone aquifer to the top of the aquitard 61 m below ground surface. Natural fractures in the shale aquitard are one possible virus transport pathway through the aquitard; however, windows, cross-connecting well bores, or imperfect grout seals along well casings also may be involved. Deep confined aquifers can be more vulnerable to contamination by human viruses than commonly believed. ?? 2007 American Chemical Society.
Holding time aware differentiated protection method for survivable waveband switching optical networks
NASA Astrophysics Data System (ADS)
Hou, Weigang; Guo, Lei; Li, Yan; Wu, Tengfei
Due to the number of wavelengths in fibers increasing, the transmission ports consumed in optical cross-connect (OXC) are greatly enhanced. To reduce the complexity and the cost of OXC, waveband switching technology is proposed. At the same time, since an optical channel carries a lot of traffic, its failure may lead to a huge data loss. Therefore, survivability in waveband switching (WBS) optical networks is important. Previous work for survivable WBS optical networks did not consider the holding time of connection request. However, in a practical network, the different connection requests generally have different holding times. This fact affects the network performances. In this paper, we propose a new method, holding time aware differentiated protection (HTADP), to provide the survivability for single-link failure in WBS optical networks. In HTADP, if the holding time of a connection request is smaller than the preset threshold, the protection path will not be assigned for saving network resources. In addition, we design a waveband integrated auxiliary graph for HTADP to well support the routing and waveband assignment. Simulation results demonstrate that HTADP not only saves more transmission ports but also is able to obtain lower blocking probability compared with previous method.
Protection schemes with waveband grooming in fault-tolerant multidomain optical networks
NASA Astrophysics Data System (ADS)
Guo, Lei; Cao, Jiannong; Wang, Xingwei; Jiang, Dingde; Yang, Ting
In wavelength-division-multiplexing networks, the fault-tolerance is very important since failures may lead to a significant amount of data loss. At the same time, the waveband switching technique is very interesting since it can save switching ports in optical cross-connections. In addition, the hierarchical routing in multidomain optical networks is very challenging since the interdomain routing is based on aggregative virtual topology. However, previous works did not jointly consider the three issues. We propose two schemes, segment-based protection (SBP) and path-based protection (PBP), to provide the fault-tolerance and waveband grooming in multidomain optical networks. In SBP, for each connection we first compute an interdomain loose route based on virtual topology, and then we compute the intradomain exact path-pairs in each single domain traversed by the loose route based on physical topology. In PBP, for each connection we first compute an interdomain loose primary path and an interdomain loose backup path based on virtual topology, and then we compute the intradomain exact paths in each single domain traversed by the loose primary path and backup path based on the physical topology. To support multidomain waveband grooming, we present the layered auxiliary graph. Simulation results show that PBP performs better than SBP.
Survivable integrated grooming in multi-granularity optical networks
NASA Astrophysics Data System (ADS)
Wu, Jingjing; Guo, Lei; Wei, Xuetao; Liu, Yejun
Survivability is an important issue to ensure the service continuity in optical network. At the same time, with the granularity of traffic demands ranging from sub-wavelength-level to wavelength-level, traffic demands need to be aggregated and carried over the network in order to utilize resources effectively. Therefore, multi-granularity grooming is proposed to save the cost and reduce the number of switching ports in Optical-Cross Connects (OXCs). However, current works mostly addressed the survivable wavelength or waveband grooming. Therefore, in this paper, we propose three heuristic algorithms called Multi-granularity Dedicated Protection Grooming (MDPG), Multi-granularity Shared Protection Grooming (MSPG) and Multi-granularity Mixed Protection Grooming (MMPG), respectively. All of them are performed based on the Survivable Multi-granularity Integrated Auxiliary Graph (SMIAG) that includes one Wavelength Integrated Auxiliary Graph (WIAG) for wavelength protection and one waveBand Integrated Auxiliary Graph (BIAG) for waveband protection. Numerical results show that MMPG has the lowest average port-cost, the best resource utilization ratio and the lowest blocking probability among these three algorithms. Compared with MDPG, MSPG has lower average port-cost, better resource utilization ratio and lower blocking probability.
IC design of low power, wide tuning range VCO in 90 nm CMOS technology
NASA Astrophysics Data System (ADS)
Zhu, Li; Zhigong, Wang; Zhiqun, Li; Qin, Li; Faen, Liu
A low power VCO with a wide tuning range and low phase noise has been designed and realized in a standard 90 nm CMOS technology. A newly proposed current-reuse cross-connected pair is utilized as a negative conductance generator to compensate the energy loss of the resonator. The supply current is reduced by half compared to that of the conventional LC-VCO. An improved inversion-mode MOSFET (IMOS) varactor is introduced to extend the capacitance tuning range from 32.8% to 66%. A detailed analysis of the proposed varactor is provided. The VCO achieves a tuning range of 27–32.5 GHz, exhibiting a frequency tuning range (FTR) of 18.4% and a phase noise of ?101.38 dBc/Hz at 1 MHz offset from a 30 GHz carrier, and shows an excellent FOM of ?185 dBc/Hz. With the voltage supply of 1.5 V, the core circuit of VCO draws only 2.1 mA DC current.
Investigating brain connectivity heritability in a twin study using diffusion imaging data
Shen, Kai-Kai; Rose, Stephen; Fripp, Jurgen; McMahon, Katie L.; de Zubicaray, Greig I.; Martin, Nicholas G.; Thompson, Paul M.; Wright, Margaret J.; Salvado, Olivier
Heritability of brain anatomical connectivity has been studied with diffusion-weighted imaging (DWI) mainly by modeling each voxel's diffusion pattern as a tensor (e.g., to compute fractional anisotropy), but this method cannot accurately represent the many crossing connections present in the brain. We hypothesized that different brain networks (i.e., their component fibers) might have different heritability and we investigated brain connectivity using High Angular Resolution Diffusion Imaging (HARDI) in a cohort of twins comprising 328 subjects that included 70 pairs of monozygotic and 91 pairs of dizygotic twins. Water diffusion was modeled in each voxel with a Fiber Orientation Distribution (FOD) function to study heritability for multiple fiber orientations in each voxel. Precision was estimated in a test–retest experiment on a sub-cohort of 39 subjects. This was taken into account when computing heritability of FOD peaks using an ACE model on the monozygotic and dizygotic twins. Our results confirmed the overall heritability of the major white matter tracts but also identified differences in heritability between connectivity networks. Inter-hemispheric connections tended to be more heritable than intra-hemispheric and cortico-spinal connections. The highly heritable tracts were found to connect particular cortical regions, such as medial frontal cortices, postcentral, paracentral gyri, and the right hippocampus. PMID:24973604
A complete design flow for silicon photonics
NASA Astrophysics Data System (ADS)
Pond, James; Cone, Chris; Chrostowski, Lukas; Klein, Jackson; Flueckiger, Jonas; Liu, Amy; McGuire, Dylan; Wang, Xu
Broad adoption of silicon photonics technology for photonic integrated circuits requires standardized design flows that are similar to what is available for analog and mixed signal electrical circuit design. We have developed a design flow that combines mature electronic design automation (EDA) software with optical simulation software. An essential component of any design flow, whether electrical or photonic, is the ability to accurately simulate largescale circuits. This is particularly important when the behavior of the circuit is not trivially related to the individual component performance. While this is clearly the case for electronic circuits consisting of hundreds to billions of transistors, it is already becoming important in photonic circuits such as WDM transmitters, where signal cross talk needs to be considered, as well as optical cross-connect switches. In addition, optical routing to connect different components requires the introduction of additional waveguide sections, waveguide bends, and waveguide crossings, which affect the overall circuit performance. Manufacturing variability can also have dramatic circuit-level consequences that need to be simulated. Circuit simulations must rely on compact models that can accurately represent the behavior of each component, and the compact model parameters must be extracted from physical level simulation and experimental results. We show how large scale circuits can be simulated in both the time and frequency domains, including the effects of bidirectional and, where appropriate, multimode and multichannel photonic waveguides. We also show how active, passive and nonlinear individual components such as grating couplers, waveguides, splitters, filters, electro-optical modulators and detectors can be simulated using a combination of electrical and optical algorithms, and good agreement with experimental results can be obtained. We then show how parameters, with inclusion of fabrication process variations, can be extracted for use in the circuit level simulations. Ultimately, we show how a multi-channel WDM transceiver can be created, from schematic design to tapeout, using key features of EDA design flows such as schematic driven layout, design rule checking and layout versus schematic.
Effect of Emergency Argon on FCF Operational Incidents
Charles Solbrig
The following report presents analyses of operational incidents which are considered in the safety analysis of the FCF argon cell and the effect that the operability of the emergency argon system has on the course of these incidents. The purpose of this study is to determine if the emergency argon system makes a significant difference in ameliorating the course of these incidents. Six incidents were considered. The following three incidents were analyzed. These are: 1. Cooling failing on 2. Vacuum Pump Failing on 3. Argon Supplies Failing on. In the remaining three incidents, the emergency argon supply would have no effect on the course of these transients since it would not come on during these incidents. The transients are 1. Loss of Cooling 2. Loss of power (Differs from above by startup delay till the Diesel Generators come on.) 3. Cell rupture due to an earthquake or other cause. The analyses of the first three incidents are reported on in the next three sections. This report is issued realizing the control parameters used may not be optimum, and additional modeling must be done to model the inertia of refrigeration system, but the major conclusion concerning the need for the emergency argon system is still valid. The timing of some events may change with a more accurate model but the differences between the transients with and without emergency argon will remain the same. Some of the parameters assumed in the analyses are Makeup argon supply, 18 cfm, initiates when pressure is = -6 iwg., shuts off when pressure is = -3.1 iwg. 170,000 ft3 supply. Min 1/7th always available, can be cross connected to HFEF argon supply dewar. Emergency argon supply, 900 cfm, initiates when pressure is = -8 iwg. shuts off when pressure is =-4 iwg. reservoir 220 ft3, refilled when tank farm pressure reduces to 1050 psi which is about 110 ft3.
Melatonin, the circadian multioscillator system and health: the need for detailed analyses of peripheral melatonin signaling.
Hardeland, Rüdiger; Madrid, Juan Antonio; Tan, Dun-Xian; Reiter, Russel J
Evidence is accumulating regarding the importance of circadian core oscillators, several associated factors, and melatonin signaling in the maintenance of health. Dysfunction of endogenous clocks, melatonin receptor polymorphisms, age- and disease-associated declines of melatonin likely contribute to numerous diseases including cancer, metabolic syndrome, diabetes type 2, hypertension, and several mood and cognitive disorders. Consequences of gene silencing, overexpression, gene polymorphisms, and deviant expression levels in diseases are summarized. The circadian system is a complex network of central and peripheral oscillators, some of them being relatively independent of the pacemaker, the suprachiasmatic nucleus. Actions of melatonin on peripheral oscillators are poorly understood. Various lines of evidence indicate that these clocks are also influenced or phase-reset by melatonin. This includes phase differences of core oscillator gene expression under impaired melatonin signaling, effects of melatonin and melatonin receptor knockouts on oscillator mRNAs or proteins. Cross-connections between melatonin signaling pathways and oscillator proteins, including associated factors, are discussed in this review. The high complexity of the multioscillator system comprises alternate or parallel oscillators based on orthologs and paralogs of the core components and a high number of associated factors with varying tissue-specific importance, which offers numerous possibilities for interactions with melatonin. It is an aim of this review to stimulate research on melatonin signaling in peripheral tissues. This should not be restricted to primary signal molecules but rather include various secondarily connected pathways and discriminate between direct effects of the pineal indoleamine at the target organ and others mediated by modulation of oscillators. PMID:22034907
The structure of the cuticular plate, an in vivo actin gel
The cuticular plate is a network of actin filaments found in hair cells of the cochlea. In the alligator lizard, it consists of rootlets, emanating from the stereocilia, and of cross-connecting actin filaments that anchor these rootlets. In thin sections, this network displays striking patches of 650 +/- 110-A striae. By quantitative analyses of the images, the mystery of the striae can be explained. They are due in part to the rootlets which are sets of flat ribbons of actin filaments. The ribbons in each set are separated by approximately 650 A. Numerous whiskers 30 A in diameter extend from each ribbon's face, interconnecting adjacent ribbons. The nonrootlet filaments, except at the margins of the cell, occur primarily as single filaments. Like the ribbons, they are bristling with whiskers. The patches of striae are explained by ribbons and filaments held at a 650-A separation by the whiskers that project from them. A simple model for regions of bewhiskered filaments is a box crammed full of randomly oriented test- tube brushes. A thin slice through the box will show regions of dark lines or striae due to the wire backbones of the brushes separated from one another by the bristle length. Using the computer instead of test- tube brushes, we have been able to model quantitatively the filament distribution and pattern of striae seen in the cuticular plate of the lizard. The organization of actin filaments we have deduced from our simulations differs from that found in macrophages or in the terminal web of intestinal epithelial cells. PMID:2592408
Interaction between disinhibited bursting and fictive locomotor patterns in the rat isolated spinal cord.
Beato, M; Nistri, A
Using a transverse barrier that allowed discrete application of neurochemicals to certain lumbar regions of the rat isolated spinal cord, we studied the intersegmental organization of rhythmic patterns recorded extracellularly from ventral roots and intracellularly from single motoneurons. Fictive locomotor patterns were elicited by serotonin (5-HT) and/or N-methyl-D-aspartate (NMDA) or high K(+) solution applied to the rostral or caudal lumbar region of the cord. Neither 4-aminopyridine nor Mg(2+)-free solution shared this property. Coapplication of strychnine and bicuculline (blockers of fast synaptic inhibition) to the caudal part elicited slow bursting in the whole cord. These bursts could trigger episodes of fictive locomotion patterns in the rostral roots. When the rostral region was exposed to 5-HT and/or NMDA (during continuous application of strychnine and bicuculline caudally) a standard locomotor-like pattern was generated during each interburst interval and was surprisingly expressed with its typical pattern alternation even in the caudal area despite the local presence of strychnine and bicuculline. Midsagittal splitting of the caudal region did not change this alternating pattern, indicating that it was driven by rostral regions above the surgical cut. Discrete changes in the concentrations of NMDA rostrally modulated the burst amplitude recorded in the same region after caudal application of strychnine and bicuculline. The period of fictive locomotor patterns changed bimodally depending on the temporal relation with disinhibited bursts, indicating a tight interaction between these two rhythmic activities. These results are interpreted on the basis of a model that assumes a modular arrangement for the locomotor central pattern generator, made up by a series of unit burst generators with serial and crossed connections. PMID:10561384
The structure of the cuticular plate, an in vivo actin gel.
DeRosier, D J; Tilney, L G
The cuticular plate is a network of actin filaments found in hair cells of the cochlea. In the alligator lizard, it consists of rootlets, emanating from the stereocilia, and of cross-connecting actin filaments that anchor these rootlets. In thin sections, this network displays striking patches of 650 +/- 110-A striae. By quantitative analyses of the images, the mystery of the striae can be explained. They are due in part to the rootlets which are sets of flat ribbons of actin filaments. The ribbons in each set are separated by approximately 650 A. Numerous whiskers 30 A in diameter extend from each ribbon's face, interconnecting adjacent ribbons. The nonrootlet filaments, except at the margins of the cell, occur primarily as single filaments. Like the ribbons, they are bristling with whiskers. The patches of striae are explained by ribbons and filaments held at a 650-A separation by the whiskers that project from them. A simple model for regions of bewhiskered filaments is a box crammed full of randomly oriented test-tube brushes. A thin slice through the box will show regions of dark lines or striae due to the wire backbones of the brushes separated from one another by the bristle length. Using the computer instead of test-tube brushes, we have been able to model quantitatively the filament distribution and pattern of striae seen in the cuticular plate of the lizard. The organization of actin filaments we have deduced from our simulations differs from that found in macrophages or in the terminal web of intestinal epithelial cells. PMID:2592408
Waveband Grooming based on Layered Auxiliary Graph in multi-domain optical networks
NASA Astrophysics Data System (ADS)
Guo, Lei; Cao, Jiannong; Wang, Xingwei; Jiang, Dingde; Yang, Ting
With the number of wavelengths on fibers keeps increasing, the size and the cost of Optical Cross-Connect (OXC) are greatly enhanced and then the control and management of optical switches become more and more complicated. Therefore, the technique called waveband switching is proposed to reduce the size and the cost of OXC; that is, to save the All-Optical (OOO) switching ports in OXC. However, the existing waveband switching algorithms are all limited in single-domain optical networks. Actually, with the scale of optical backbone keeps enlarging, the network is divided to multiple independent domains to perform the hierarchy routing for achieving the scalability. In order to reduce the size and the cost of OXC meanwhile to achieve the scalability in multi-domains, in this paper we propose a new heuristic algorithm called Waveband Grooming with Layered Auxiliary Graph (WGLAG) since the waveband grooming problem is the NP-hard to perform the inter-domain routing based on the virtual topology of multi-domain network and the intra-domain routing based on the physical topology of single-domain network. In intra-domain routing with waveband grooming of each single-domain, we propose the Layered Auxiliary Graph (LAG) that includes one virtual topology layer and multiple waveband-plane layers to compute a single-hop, or multi-hop or hybrid waveband route for each connection request based on the sub-path waveband grooming scheme. Simulation results show that, WGLAG not only can effectively save more switching ports to reduce the cost of OXC but also can obtain lower blocking probability than other algorithm.
Design of physical and logical topologies with fault-tolerant ability in wavelength-routed optical network
NASA Astrophysics Data System (ADS)
Chen, Chunfeng; Liu, Hua; Fan, Ge
In this paper we consider the problem of designing a network of optical cross-connects(OXCs) to provide end-to-end lightpath services to label switched routers (LSRs). Like some previous work, we select the number of OXCs as our objective. Compared with the previous studies, we take into account the fault-tolerant characteristic of logical topology. First of all, using a Prufer number randomly generated, we generate a tree. By adding some edges to the tree, we can obtain a physical topology which consists of a certain number of OXCs and fiber links connecting OXCs. It is notable that we for the first time limit the number of layers of the tree produced according to the method mentioned above. Then we design the logical topologies based on the physical topologies mentioned above. In principle, we will select the shortest path in addition to some consideration on the load balancing of links and the limitation owing to the SRLG. Notably, we implement the routing algorithm for the nodes in increasing order of the degree of the nodes. With regarding to the problem of the wavelength assignment, we adopt the heuristic algorithm of the graph coloring commonly used. It is clear our problem is computationally intractable especially when the scale of the network is large. We adopt the taboo search algorithm to find the near optimal solution to our objective. We present numerical results for up to 1000 LSRs and for a wide range of system parameters such as the number of wavelengths supported by each fiber link and traffic. The results indicate that it is possible to build large-scale optical networks with rich connectivity in a cost-effective manner, using relatively few but properly dimensioned OXCs.
A review of outbreaks of waterborne disease associated with ships: evidence for risk management.
Rooney, Roisin M.; Bartram, Jamie K.; Cramer, Elaine H.; Mantha, Stacey; Nichols, Gordon; Suraj, Rohini; Todd, Ewen C. D.
OBJECTIVE: The organization of water supply to and on ships differs considerably from that of water supply on land. Risks of contamination can arise from source water at the port or during loading, storage, or distribution on the ship. The purpose of this article is to review documented outbreaks of waterborne diseases associated with passenger, cargo, fishing, and naval ships to identify contributing factors so that similar outbreaks can be prevented in the future. METHODS: The authors reviewed 21 reported outbreaks of waterborne diseases associated with ships. For each outbreak, data on pathogens/toxins, type of ship, factors contributing to outbreaks, mortality and morbidity, and remedial action are presented. RESULTS: The findings of this review show that the majority of reported outbreaks were associated with passenger ships and that more than 6,400 people were affected. Waterborne outbreaks due to Enterotoxigenic Escherichia coli, noroviruses, Salmonella spp, Shigella sp, Cryptosporidium sp, and Giardia lamblia occurred on ships. Enterotoxigenic E. coli was the pathogen most frequently associated with outbreaks. One outbreak of chemical water poisoning also occurred on a ship. Risk factors included contaminated port water, inadequate treatment, improper loading techniques, poor design and maintenance of storage tanks, ingress of contamination during repair and maintenance, cross-connections, back siphonage, and insufficient residual disinfectant. CONCLUSIONS: Waterborne disease outbreaks on ships can be prevented. The factors contributing to outbreaks emphasize the need for hygienic handling of water along the supply chain from source to consumption. A comprehensive approach to water safety on ships is essential. This may be achieved by the adoption of Water Safety Plans that cover design, construction, operation, and routine inspection and maintenance. PMID:15219801
Fiber optic DTS in sealed and heated boreholes for active groundwater flow characterization
NASA Astrophysics Data System (ADS)
Coleman, Thomas; Parker, Beth; Cherry, John; Mondanos, Michael
In recent years, advances in technology have allowed temperature profiling to evolve to offer new insight into fractured rock hydrogeology. Temperature profiles in open boreholes within fractured rock have long been used to identify and characterize flow in the rock formation and/or in the borehole. An advance in temperature logging makes use of precision temperature profiles collected using wireline trolling methods in a heated borehole to identify fractures with active groundwater flow by creating a thermal disequilibrium and monitoring the temperature response. A second development is based on collecting wireline temperature profiles within a sealed borehole to eliminate short circuiting effects caused by the open borehole conduit. The borehole is temporarily sealed with a flexible impervious fabric liner so that the water column in the borehole is static and cross-connection is eliminated. Though highly precise temperature and spatial measurements are possible using these techniques, the temporal resolution is limited by the rate at which the wireline probe can be raised and lowered in the borehole. There is a need to measure temperature profiles continuously over time to characterize transient processes. Fibre optic distributed temperature sensing (DTS) is a technique that allows for collecting temperature profiles continuously. This tool was advanced by the oil and gas industry for collecting temperature data in multi kilometer deep boreholes over relatively coarse measurement scales. In contrast, very fine spatial and temperature resolutions are needed for freshwater contaminant fractured rock hydrogeology where the scale of interest is much more acute. Recent advances in the spatial, temperature, and temporal resolution of DTS systems allow this technology to be adapted well to the shallow subsurface environment. This project demonstrates the first application of DTS used in conjunction with flexible borehole liners in a heated borehole environment. The integration of DTS, active heating, and lined boreholes was tested in the context of fractured rock site characterization. DTS heat pulse tests were carried out in two boreholes located at a well characterized research site in Guelph, ON, Canada. The capabilities for long-term and high temporal resolution site monitoring and characterization from the developed methods were assessed. The results of this technique are promising and indicate evidence for identifying active groundwater flow. Advancements to the DTS heat pulse method are possible to offer further improved insight into natural groundwater flow systems.
"I CAMMINI DELLA REGINA" - Open Source based tools for preserving and culturally exploring historical traffic routes.
NASA Astrophysics Data System (ADS)
Cannata, Massimiliano; Colombo, Massimo; Antonovic, Milan; Cardoso, Mirko; Delucchi, Andrea; Gianocca, Giancarlo; Brovelli, Maria Antonia
"I CAMMINI DELLA REGINA" (The Via Regina Paths) is an Interreg project funded within the transnational cooperation program between Italy and Switzerland 2007-2013. The aim of this project is the preservation and valorization of the cultural heritage linked to the walking historically paths crossing, connecting and serving the local territories. With the approach of leveraging the already existing tools, which generally consist of technical descriptions of the paths, the project uses the open source geospatial technologies to deploy innovative solutions which can fill some of the gaps in historical-cultural tourism offers. The Swiss part, and particularly the IST-SUPSI team, has been focusing its activities in the realization of two innovative solutions: a mobile application for the survey of historical paths and a storytelling system for immersive cultural exploration of the historical paths. The former, based on Android, allows to apply in a revised manner a consolidated and already successfully used methodology of survey focused on the conservation of the historical paths (Inventory of historical traffic routes in Switzerland). Up to now operators could rely only on hand work based on a combination of notes, pictures and GPS devices synthesized in manually drawn maps; this procedure is error prone and shows many problems both in data updating and extracting for elaborations. Thus it has been created an easy to use interface which allows to map, according to a newly developed spatially enabled data model, paths, morphological elements, and multimedia notes. When connected to the internet the application can send the data to a web service which, after applying linear referencing and further elaborating the data, makes them available using open standards. The storytelling system has been designed to provide users with cultural insights embedded in a multimedial and immersive geospatial portal. Whether the tourist is exploring physically or virtually the desired historical path, the system will provide notifications and immersive multimedia information that foster a new sight of the territory: award of the culture and history of the place thanks to attractive description of the geological, land use, historical and ethnographic contexts. The technologies used for these developments are: mongoDB, tornado, Android SDK, geoserver, bootstrap, OpenLayers, HTML5, CSS3, JQuery. The approach, methodologies and technical implementations will be discussed and presented.
Assessment of drinking water quality using ICP-MS and microbiological methods in the Bholakpur area, Hyderabad, India.
Abdul, Rasheed M; Mutnuri, Lakshmi; Dattatreya, Patil J; Mohan, Dayal A
A total of 16 people died and over 500 people were hospitalized due to diarrhoeal illness in the Bholakpur area of Hyderabad, India on 6th May 2009. A study was conducted with immediate effect to evaluate the quality of municipal tap water of the Bholakpur locality. The study consists of the determination of physico-chemical properties, trace metals, heavy metals, rare earth elements and microbiological quality of drinking water. The data showed the variation of the investigated parameters in samples as follows: pH 7.14 to 8.72, EC 455 to 769 ?S/cm, TDS 303.51 to 515.23 ppm and DO 1.01 to 6.83 mg/L which are within WHO guidelines for drinking water quality. The water samples were analyzed for 27 elements (Li, Be, B, Na, Mg, Al, Si, K, Ca, V, Cr, Mn, Fe, Ni, Co, Cu, Zn, As, Se, Rb, Sr, Mo, Ag, Cd, Sb, Ba and Pb) using inductively coupled plasma-mass spectrometry (ICP-MS). The concentrations of Fe (0.12 to 1.13 mg/L), Pb (0.01 to 0.07 mg/L), Cu (0.01 to 0.19 mg/L), Ni (0.01 to 0.15 mg/L), Al (0.16 to 0.49 mg/L), and Na (38.36 to 68.69 mg/L) were obtained, which exceed the permissible limits of the World Health Organization (WHO) for drinking water quality guidelines. The remaining elements were within the permissible limits. The microbiological quality of water was tested using standard plate count, membrane filtration technique, thermotolerant coliform (TTC), and most probable number (MPN) methods. The total heterotrophic bacteria ranged from 1.0 × 10(5) to 18 × 10(7 )cfu/ml. Total viable bacteria in all the water samples were found to be too numerable to count and total number of coliform bacteria in all water samples were found to be of order of 1,100 to >2,400 MPN index/100 ml. TTC tested positive for coliform bacteria at 44.2°C. All the water samples of the study area exceeded the permissible counts of WHO and that (zero and minimal counts) of the control site (National Geophysical Research Institute) water samples. Excessively high colony numbers indicate that the water is highly contaminated with microorganisms and is hazardous for drinking purposes. Bacteriological pollution of drinking water supplies caused diarrhoeal illness in Bholakpur, which is due to the infiltration of contaminated water (sewage) through cross connection, leakage points, and back siphoning. PMID:21544503
A mathematical model for the mechanism of rapid eye movements induced by an anticholinesterase in the decerebrate cat.
Pompeiano, O; Valentinuzzi, M
The oculomotor pattern which appears in intact preparations during desynchronized sleep is characterized by the irregular occurrence of isolated ocular movements and bursts of rapid eye movements (REM). This complex oculomotor pattern results from the activity of two premotor structures which influence the extraocular motoneurons during this phase of sleep: one is located in the pontine reticular formation, the other in the vestibular nuclei. In the decerebrate preparation the intravenous injection of an anticholinesterase leads to the appearance of a typical pattern of oculomotor activity, which differs from that occurring during physiological sleep in so far as it consists quite exclusively of bursts of REM which appear at very regular intervals. Lesion experiments as well as unit recordings have shown that these bursts of REM depend in particular upon rhythmic discharges of the vestibular nuclear neurons. The underlying anatomical structures responsible for these bursts of REM are therefore the vestibular nuclei, the oculomotor nuclei and the oculo-orbital system. This mechanism is under the influence of cholinergic reticular neurons which generate the oculomotor rhythm. We have postulated the existence of a self-excitatory cholinergic system, located in the pontine reticular formation, whose steady discharge impinges upon an oscillatory neuronal system located in the dorso-lateral pontine tegmentum, which transforms the tonic input into a sinusoidal final output. We have assumed also that the periodic increases in the discharge frequency of this oscillatory system trigger a fast phase generator acting on the different components of the REM system, and that the behavior of each component follows a first-order differential equation. The state of excitation of the components of the system is defined as proportional to frequency of nerve impulses. Assuming ipsilateral and crossed connections, a pattern of oculomotor activity is obtained that simulates the experimental oculomotor output fairly well. The repetition of the eye jerks is described by a Fourier series. The model proposed in this paper may be taken as a first approach in describing the generation mechanism of REM, and as a theoretical guide to new experimental researches and the development of other more realistic models. PMID:190960
High-Resolution Flow Logging for Hydraulic Characterization of Boreholes and Aquifer Flow Zones at Contaminated Bedrock Sites
NASA Astrophysics Data System (ADS)
Williams, J. H.; Johnson, C. D.; Paillet, F. L.
In the past, flow logging was largely restricted to the application of spinner flowmeters to determine flow-zone contributions in large-diameter production wells screened in highly transmissive aquifers. Development and refinement of tool-measurement technology, field methods, and analysis techniques has greatly extended and enhanced flow logging to include the hydraulic characterization of boreholes and aquifer flow zones at contaminated bedrock sites. State-of-the-art in flow logging will be reviewed, and its application to bedrock-contamination investigations will be presented. In open bedrock boreholes, vertical flows are measured with high-resolution flowmeters equipped with flexible rubber-disk diverters fitted to the nominal borehole diameters to concentrate flow through the measurement throat of the tools. Heat-pulse flowmeters measure flows in the range of 0.05 to 5 liters per minute, and electromagnetic flowmeters measure flows in the range of 0.3 to 30 liters per minute. Under ambient and low-rate stressed (either extraction or injection) conditions, stationary flowmeter measurements are collected in competent sections of the borehole between fracture zones identified on borehole-wall images. Continuous flow, fluid-resistivity, and temperature logs are collected under both sets of conditions while trolling with a combination electromagnetic flowmeter and fluid tool. Electromagnetic flowmeters are used with underfit diverters to measure flow rates greater than 30 liters per minute and suppress effects of diameter variations while trolling. A series of corrections are applied to the flow-log data to account for the zero-flow response, bypass, trolling, and borehole-diameter biases and effects. The flow logs are quantitatively analyzed by matching simulated flows computed with a numerical model to measured flows by varying the hydraulic properties (transmissivity and hydraulic head) of the flow zones. Several case studies will be presented that demonstrate the integration of flow logging in site-characterization activities framework; 2) evaluate cross-connection effects and determine flow-zone contributions to water-quality samples from open boreholes; and 3) design discrete-zone hydraulic tests and monitoring-well completions.
BOOK REVIEW: Equations of Motion in General Relativity Equations of Motion in General Relativity
NASA Astrophysics Data System (ADS)
Schäfer, Gerhard
Devoted exclusively to the problem of motion in general relativity, this book by H. Asada, T. Futamase, and P. A. Hogan is highly welcome to close up a gap in the book sector presenting a concise account of theoretical developments and results on gravitational equations of motion achieved since the discovery of the binary neutron star system PSR 1913+16 in 1974. For the most part, the book is concerned with the development and application of the important post-Newtonian approximation (PNA) framework which allows for highly efficient approximate analytic solutions of the Einstein field equations for many-body systems in terms of a slow-motion and weak-field ordering parameter. That approximation scheme is shown to be applicable also to the external motion of strongly self-gravitating objects if their internal dynamics is frozen in (strong field point particle limit) and the external conditions fit. Relying on the expertise of the authors, the PNA framework is presented in a form which, at the 1PNA level, had become famous through the work by Einstein, Infeld and Hoffmann in 1938; therein, surface integrals over gravitational field expressions in the outside-body regime play a crucial role. Other approaches which also succeeded with the highest achieved PNA level so far are mentioned too, if not fully exhaustively with respect to the highest, the 3.5PNA level which contains the inverse power of the speed of light to the seventh order. Regarding the 3PNA, the reader gains a clear understanding of how the equations of motion for binary systems with compact components come about. Remarkably, no deviation from four-dimensional space-time is needed. Various explicit analytic expressions are derived for binary systems: the periastron advance and the orbital period at the 2PNA, the orbital decay through gravitational radiation reaction at the 2.5PNA, and effects of the gravitational spin-orbit and spin-spin couplings on the orbital motion. Also the propagation of light-like signals in gravitational fields of binary systems is treated, which is important for a precise interpretation of pulsar observation measurements. Based on original research by the authors, a detailed presentation is given of a mathematical scheme which makes feasible the treatment of small black holes in background space-times. Using that approach, the equations of motion of small charged black holes are derived in vacuum Einstein-Maxwell space-times without encountering infinities, showing up electromagnetic radiation reaction, background field, and tail forces. At this stage, the book defines various issues to be tackled in future research within the given formalism, such as a physical understanding of the very structure of the tail contribution or a more detailed calculation of the motion of a small Schwarzschild black hole in an external vacuum gravitational field. A unique chapter is devoted to the choreographic three-body solution of the 1PNA dynamics, also mentioning the 2PNA dynamics, in the form of figure-eight configurations. The emitted gravitational waves are shown, and a discussion of their observability in future gravitational wave astronomy is given. Four appendices support and complement the main part of the book. Here, the far zone non-contribution to the equations of motion at 3PNA is carefully investigated, forces resulting from the extendedness of objects are presented in analytic form, null geodesic congruences with their optical scalars are discussed, and the perturbed vacuum Einstein-Maxwell field equations are given. The book delivers a very readable account of the problem of motion in general relativity. It covers the state of the art up to the years 2006/8 and presents a plethora of interesting and important topics and results. Whenever appropriate, connection with observation is made. A reader with good post-introductory knowledge of the theory of general relativity should find easy access to the book, and will surely benefit from the mathematical and conceptual issues elaborated on therein. Being of observational relevance too, the
A Multiple-Tracer Approach for Identifying Sewage Sources to an Urban Stream System
Hyer, Kenneth Edward
The presence of human-derived fecal coliform bacteria (sewage) in streams and rivers is recognized as a human health hazard. The source of these human-derived bacteria, however, is often difficult to identify and eliminate, because sewage can be delivered to streams through a variety of mechanisms, such as leaking sanitary sewers or private lateral lines, cross-connected pipes, straight pipes, sewer-line overflows, illicit dumping of septic waste, and vagrancy. A multiple-tracer study was conducted to identify site-specific sources of sewage in Accotink Creek, an urban stream in Fairfax County, Virginia, that is listed on the Commonwealth's priority list of impaired streams for violations of the fecal coliform bacteria standard. Beyond developing this multiple-tracer approach for locating sources of sewage inputs to Accotink Creek, the second objective of the study was to demonstrate how the multiple-tracer approach can be applied to other streams affected by sewage sources. The tracers used in this study were separated into indicator tracers, which are relatively simple and inexpensive to apply, and confirmatory tracers, which are relatively difficult and expensive to analyze. Indicator tracers include fecal coliform bacteria, surfactants, boron, chloride, chloride/bromide ratio, specific conductance, dissolved oxygen, turbidity, and water temperature. Confirmatory tracers include 13 organic compounds that are associated with human waste, including caffeine, cotinine, triclosan, a number of detergent metabolites, several fragrances, and several plasticizers. To identify sources of sewage to Accotink Creek, a detailed investigation of the Accotink Creek main channel, tributaries, and flowing storm drains was undertaken from 2001 to 2004. Sampling was conducted in a series of eight synoptic sampling events, each of which began at the most downstream site and extended upstream through the watershed and into the headwaters of each tributary. Using the synoptic sampling approach, 149 sites were sampled at least one time for indicator tracers; 52 of these sites also were sampled for confirmatory tracers at least one time. Through the analysis of multiple-tracer levels in the synoptic samples, three major sewage sources to the Accotink Creek stream network were identified, and several other minor sewage sources to the Accotink Creek system likely deserve additional investigation. Near the end of the synoptic sampling activities, three additional sampling methods were used to gain better understanding of the potential for sewage sources to the watershed. These additional sampling methods included optical brightener monitoring, intensive stream sampling using automated samplers, and additional sampling of several storm-drain networks. The samples obtained by these methods provided further understanding of possible sewage sources to the streams and a better understanding of the variability in the tracer concentrations at a given sampling site. Collectively, these additional sampling methods were a valuable complement to the synoptic sampling approach that was used for the bulk of this study. The study results provide an approach for local authorities to use in applying a relatively simple and inexpensive collection of tracers to locate sewage sources to streams. Although this multiple-tracer approach is effective in detecting sewage sources to streams, additional research is needed to better detect extremely low-volume sewage sources and better enable local authorities to identify the specific sources of the sewage once it is detected in a stream reach.
Simulation of external contamination into water distribution systems through defects in pipes
NASA Astrophysics Data System (ADS)
López, P. A.; Mora, J. J.; García, F. J.; López, G.
Water quality can be defined as a set of properties (physical, biological and chemical) that determine its suitability for human use or for its role in the biosphere. In this contribution we focus on the possible impact on water distribution systems quality of external contaminant fluids entering through defects in pipes. The physical integrity of the distribution system is a primary barrier against the entry of external contaminants and the loss in quality of the treated drinking water, but this integrity can be broken. Deficiencies in physical and hydraulic integrity can lead into water losses, but also into the influx of contaminants through pipes walls, either through breaks coming from external subsoil waters, or via cross connections coming from sewerage or other facilities. These external contamination events (the so called pathogen intrusion phenomenon) can act as a source of income by introducing nutrients and sediments as well as decreasing disinfectant concentrations within the distribution system, thus resulting in a degradation of the distribution water quality. The objective of this contribution is to represent this pathogen intrusion phenomenon. The combination of presence of defects in the infrastructures (equipment failure), suppression and back-siphonage and lack of disinfection is the cause of propagation of contamination in the clean current of water. Intrusion of pathogenic microorganisms has been studied and registered even in well maintained services. Therefore, this situation can happen when negative pressure conditions are achieved in the systems combined with the presence of defects in pipes nearby the suppression. A simulation of the process by which the external fluids can come inside pipes across their defects in a steady-state situation will be considered, by using different techniques to get such a successful modeling, combining numerical and experimental simulations. The proposed modeling process is based on experimental and computational simulations. An analysis of the intrusion behavior considering hydrodynamic and transportation of pollutant phenomena has been developed, comparing the influence of the turbulence consideration and the agreement of both computational and experimental results. This paper is focused on the analysis of such external intrusion phenomenon, the relationship between the income flow and the pressure inside the pipe, depending on the characteristics of the defect and the pressure level, as well as the effect on the water quality of the income substances dispersion. Two different experiments have been developed. In order to represent the intrusion phenomenon in steady state, two suitable assemblies have been implemented in the laboratory. In a lower order of pressures a Venturi tube has been used for generating the depression. In a higher level of pressures, a pumping system has been used. The defect on the pipe has been simulated by a circular hole, and the dispersion of pollutant has been considered by means of salinity as a conservative contaminant. The simulated scenarios of different suppressions can vary from 0.001 to 0.7 bars. The prototypes are also simulated by numerical modeling in two and three dimensions using Computational Fluid Dynamics techniques. For this purpose Fluent 6.3™ has been used, which displays the fields of hydrodynamic components and salinity. After doing a proper calibration process, the contrast made between models will allows us to establish the foundation for further pathogen intrusion simulations in the distribution system. Different turbulent models based on turbulent viscosity and different boundary conditions will also be considered. The agreement between experimental and computational models will be analyzed, and the differences between series of results will be compared, validating thus the use of computational models for representing the pathogen intrusion problem. By both, mathematical and physical models, it is intended to have a better knowledge of quantities that can not be measured, such as velocity fields, aspects of t
The simple perfection of quantum correlation in human vision.
Bouman, Maarten A
A theory is presented that specifies the amount of light that is needed for the perception of any stimulus that is defined in space, time and color. For detection and discrimination mechanistic neural elements with deterministic procedures exist. Twin pairs of red and green cones are ordered in three sets along clockwise and counter clockwise revolving spirals and along circles around the center of the fovea. In the rod-free fovea the red pairs are ordered along the spirals and the green along the circles. Each cone is accompanied by--dependent on retinal eccentricity--up to 100 satellite rods. For the retinal signal processing such a receptor group constitutes a space-quantum in analogy with time-quanta of about 0.04 s. In the peripheral retina the red and green twin pairs of space-quanta are roughly ordered along and at random distributed over the spirals and circles. Over each time-quantum, the cone and rods of a space-quantum sum their responses in a common nerve circuit of the luminosity channel. The summation's results from twin pairs of the same set of space-quanta are correlated by two-fold spatio-temporal coincidence mechanisms in the retina. Their outcome signals the perception of light, movement and edge. In the fused binocular visual field the movement and edge signals of the three sets from both eyes perfectly join vectorially together, provided the responding pairs of space-quanta are binocularly in perfect register as they normally are. The receptor's Weber gain control makes the receptor an all-or-none-system. The space-quantum's De Vries gain control makes its sensitivity equal to the average of the poisson fluctuations in quantum absorption per time-quantum. The controls are based on, respectively, arithmetically feed forward and backward inhibitive nerve mechanisms. The thermal noise of the photo-pigment resets the controls. The response to the second quantum absorption in a time-quantum in the individual rod, red or green cone has accession to the white, red or green nerve color circuit, respectively, and produces there a corresponding color signal. Already a single absorption in a blue cone is for a blue signal. In the retina, for the generation of yellow signals, the color circuits of individual red and green cones of each mixed entwined triple of red and green twin pairs of space-quanta are cross-connected through a nerve opponent color circuit. In the lateral geniculate nucleus in groups of seven neighboring triples, through two nerve opponent color circuits that are common for the two eyes together, the red and green signals as well as the yellow and blue mutually annihilate each other's color. White signals remain. In anomalous trichromacy, the space-quanta of some pairs have different cones or in one of them the cone is missing. In dichromacy, all pairs have different cones or one type of cones is missing. For perceptive resolution the periodic scanning of the retinal image by the eye tremor in synchrony with the time-quanta, overrules the limit of optical resolution as set by diffraction in the eye optics. Dependent on pupil diameter the scanning contributes up to a factor of about 30 to resolution. The action potentials of the Purkinje cells in the myocardium generate the time-quanta of the central nervous system as well as the mechanical scanning of the retinal image through the synchronic periodic variation of the tonus in the eye muscles. PMID:16377059
Microbial Health Risks Associated with Exposure to Stormwater in a Water Plaza
NASA Astrophysics Data System (ADS)
Sales-Ortells, Helena; Medema, Gertjan
Climate change scenarios predict an increase of intense rainfall events in summer in Western Europe. Current urban drainage systems cannot cope with such intense precipitation events. Cities are constructing local stormwater storage facilities to prevent pluvial flooding. Combining storage with other functions, such as recreation, may lead to exposure to contaminants. This study assessed the microbial quality of rainwater collected in a water plaza in Rotterdam (The Netherlands) and the health risks associated with recreational exposure. The water plaza collects street run-off, diverges first flush to the sewer system and stores the rest of the run-off in the plaza as open water. A rain simulation experiment was conducted using drinking water from fire hydrants. The water flowed over the street pavement into the street gutters and into the square. Samples were collected from the first flush diverted water and from two different levels of the water plaza at different points in time. Campylobacter spp., Cryptosporidium, and Legionella pneumophila were the pathogens investigated, using quantitative PCR. Escherichia coli was quantified with culture methods to obtain information on faecal contamination. Microbial source tracking tools (human Bacteroides, avian Helicobacter and canine mitochondrial DNA, all analysed with quantitative PCR) were used to determine the origin (human, animal) of the intestinal pathogens. To estimate the health risks for children playing in the water plaza after a rain event, a quantitative microbial risk assessment model was built. The volume of water ingested was obtained from literature on similar locations (flooded streets). Published dose-response models were used to calculate the risk per event. Exposure frequency was estimated using weather data (precipitation events). E. coli concentrations were below the level for excellent bathing water in the EU Bathing Water Directive. Cryptosporidium was not found in any sample. Campylobacter spp. was found in all samples, with higher concentrations in samples that contained human Bacteroides than in samples with contamination from birds and dogs (15 vs 3.7 gc (genomic copies)/100mL). In both cases, the estimated disease risk associated with Campylobacter and recreational exposure to the water plaza were higher than the Dutch national incidence. This indicates that the health risk associated with recreational exposure to the water plaza is significant. L. pneumophila was found only in two out of ten pond samples. Legionnaire's disease risks were lower than the Dutch national incidence. However,higher health risks are expected in the future because of increased frequency of rain events. Presence of human Bacteroides indicates possible cross-connections with the combined sewer system that should be identified and removed to reduce the gastrointestinal disease risks. Other measures include cleaning/disinfection of the water plaza after extreme precipitation; increasing the capacity of the first flush pump; regular cleaning of the catchment area and gutters; informing the neighbours of the importance of keeping the streets clean of pets depositions; and informing the public about the health risks derived from recreational uses of the water plaza after rain events. Finally, monitoring the water quality during real rain events is recommended to better characterize the health risks.
Evaluation of long-term water-level declines in basalt aquifers near Mosier, Oregon
Burns, Erick R.; Morgan, David S.; Lee, Karl K.; Haynes, Jonathan V.; Conlon, Terrence D.
The Mosier area lies along the Columbia River in northwestern Wasco County between the cities of Hood River and The Dalles, Oregon. Major water uses in the area are irrigation, municipal supply for the city of Mosier, and domestic supply for rural residents. The primary source of water is groundwater from the Columbia River Basalt Group (CRBG) aquifers that underlie the area. Concerns regarding this supply of water arose in the mid-1970s, when groundwater levels in the orchard tract area began to steadily decline. In the 1980s, the Oregon Water Resources Department (OWRD) conducted a study of the aquifer system, which resulted in delineation of an administrative area where parts of the Pomona and Priest Rapids aquifers were withdrawn from further appropriations for any use other than domestic supply. Despite this action, water levels continued to drop at approximately the same, nearly constant annual rate of about 4 feet per year, resulting in a current total decline of between 150 and 200 feet in many wells with continued downward trends. In 2005, the Mosier Watershed Council and the Wasco Soil and Water Conservation District began a cooperative investigation of the groundwater system with the U.S. Geological Survey. The objectives of the study were to advance the scientific understanding of the hydrology of the basin, to assess the sustainability of the water supply, to evaluate the causes of persistent groundwater-level declines, and to evaluate potential management strategies. An additional U.S. Geological Survey objective was to advance the understanding of CRBG aquifers, which are the primary source of water across a large part of Oregon, Washington, and Idaho. In many areas, significant groundwater level declines have resulted as these aquifers were heavily developed for agricultural, municipal, and domestic water supplies. Three major factors were identified as possible contributors to the water-level declines in the study area: (1) pumping at rates that are not sustainable, (2) well construction practices that have resulted in leakage from aquifers into springs and streams, and (3) reduction in aquifer recharge resulting from long-term climate variations. Historical well construction practices, specifically open, unlined, uncased boreholes that result in cross-connecting (or commingling) multiple aquifers, allow water to flow between these aquifers. Water flowing along the path of least resistance, through commingled boreholes, allows the drainage of aquifers that previously stored water more efficiently. The study area is in the eastern foothills of the Cascade Range in north central Oregon in a transitional zone between the High Cascades to the west and the Columbia Plateau to the east. The 78-square mile (mi2) area is defined by the drainages of three streams - Mosier Creek (51.8 mi2), Rock Creek (13.9 mi2), and Rowena Creek (6.9 mi2) - plus a small area that drains directly to the Columbia River.The three major components of the study are: (1) a 2-year intensive data collection period to augment previous streamflow and groundwater-level measurements, (2) precipitation-runoff modeling of the watersheds to determine the amount of recharge to the aquifer system, and (3) groundwater-flow modeling and analysis to evaluate the cause of groundwater-level declines and to evaluate possible water resource management strategies. Data collection included the following: 1. Water-level measurements were made in 37 wells. Bi-monthly or quarterly measurements were made in 30 wells, and continuous water-level monitoring instruments were installed in 7 wells. The measurements principally were made to capture the seasonal patterns in the groundwater system, and to augment the available long-term record. 2. Groundwater pumping was measured, reported, or estimated from irrigation, municipal and domestic wells. Flowmeters were installed on 74 percent of all high-capacity irrigation wells in the study area. 3. Borehole geophysical data were collected from a known commingling well. These data measured geologic properties and vertic