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7,600 | Suppose that you have an abstract for a scientific paper: the wetting flows are controlled by the contact line motion .
we derive an equation that describes the slow time evolution of the triple solid - liquid - fluid contact line for an arbitrary distribution of defects on a solid surface .
the capillary rise along a partially wetted infinite vertical wall is considered .
the contact line is assumed to be only slightly deformed by the defects .
the derived equation is solved exactly for a simple example of a single defect . .
And you have already written the first three sentences of the full article: the wetting flows ( where the triple solid - liquid - fluid contact line is present ) are important for many practical applications ranging from the metal coating to the medical treatment of the lung airways .
the contact line statics and dynamics attracted a lot of attention from the scientific community during the last decades .
it became clear that the hydrodynamics in the region of the liquid wedge close to the contact line ( which we will call clr - contact line region ) differs from the hydrodynamics in the bulk of the liquid ..
Please generate the next two sentences of the article | because of the contact line singularity @xcite , the fluid motion in presence of the contact line appears to be much slower than without it .
this difference can be accounted for by the introduction of the anomalously large energy dissipation inside the clr @xcite . for practical purposes |
7,601 | Suppose that you have an abstract for a scientific paper: realizing a quantum transistor built of molecules or quantum dots has been one of the most ambitious challenges in nanotechnology . even though remarkable progress has been made , being able to gate and control nanometer scale objects , as well to interconnect them to achieve scalability
remains extremely difficult .
most experiments concern a single quantum dot or molecule , and they are made at ultra low temperature to avoid decoherence and tunneling .
we propose to use canonical transformations to design quantum devices that are protected by symmetry , and therefore , may be operational at high temperatures .
we illustrate the idea with examples of quantum transistor architectures that can be connected both in series and parallel . .
And you have already written the first three sentences of the full article: thanks to advances in nanofabrication , experimentalist can routinely manufacture nanostructures that resemble artificial atoms quantum dots that can be manipulated with an extreme degree of control@xcite .
the degree of tunability is such , that one can see a state with a single electron sitting at the dot , and even control and detect its spin . by tuning a gate voltage
one can also control the transport through the dot in what is regarded as a single - electron transistor ..
Please generate the next two sentences of the article | the techniques used to construct these devices can also be applied to build structures with multiple dots , and suggest that scalability to circuits of many quantum dots should be technologically achievable .
another avenue that has been pursued is using molecules to build transistors , instead of quantum dots@xcite . |
7,602 | Suppose that you have an abstract for a scientific paper: the pioneer 10/11 spacecraft yielded the most precise navigation in deep space to date .
however , their radiometric tracking data has consistently indicated the presence of a small , anomalous , doppler frequency drift .
the drift is a blue shift , uniformly changing with a rate of @xmath0 hz / s and can be interpreted as a constant sunward acceleration of each particular spacecraft of @xmath1 m / s@xmath2 ( or , alternatively , a time acceleration of @xmath3 s / s@xmath2 ) .
this signal has become known as the pioneer anomaly ; the nature of this anomaly remains unexplained .
we discuss the current state of the efforts to retrieve the entire data sets of the pioneer 10 and 11 radiometric doppler data .
we also report on the availability of recently recovered telemetry files that may be used to reconstruct the engineering history of both spacecraft using original project documentation and newly developed software tools .
we discuss possible ways to further investigate the discovered effect using these telemetry files in conjunction with the analysis of the much extended pioneer doppler data . in preparation for this new upcoming investigation , we summarize the current knowledge of the pioneer anomaly and review some of the mechanisms proposed for its explanation .
we emphasize the main objectives of this new study , namely analysis of the early data that could yield the true direction of the anomaly and thus , its origin , analysis of planetary encounters , that should tell more about the onset of the anomaly ( e.g. pioneer 11 s saturn flyby ) , analysis of the entire dataset , that should lead to a better determination of the temporal behavior of the anomaly , comparative analysis of individual anomalous accelerations for the two pioneers with the data taken from similar heliocentric distances , the detailed study of on - board systematics , and development of a thermal - electric - dynamical model using on - board telemetry .
the outlined strategy may allow for....
And you have already written the first three sentences of the full article: the pioneer 10/11 missions were the first spacecraft to explore the outer solar system @xcite .
their objectives were to conduct , during the 1972 - 73 jovian opportunities , exploratory investigation beyond the orbit of mars of the interplanetary medium , the nature of the asteroid belt , and the environmental and atmospheric characteristics of jupiter and saturn ( for pioneer 11 ) .
pioneer 10 was launched on 2 march 1972 on top of an atlas / centaur / te364 - 4 launch vehicle ..
Please generate the next two sentences of the article | the launch marked the first use of the atlas - centaur as a three - stage launch vehicle .
the third stage was required to rocket pioneer 10 to the speed of 14.39 km / s needed for the flight to jupiter . its sister craft , pioneer 11 , was launched on 5 april 1973 , like pioneer 10 , also on top of an atlas / centaur / te364 - 4 launch vehicle . after safe passage through the asteroid belt on 19 april 1974 , pioneer 11 s thrusters were fired to add another 63.7 m / s to the spacecraft s velocity . |
7,603 | Suppose that you have an abstract for a scientific paper: we report the results of a globally coordinated photometric campaign to search for transits by the @xmath0 and @xmath1 outer planets of the 3-planet system orbiting the nearby m - dwarf gl 876 .
these two planets experience strong mutual perturbations , which necessitate use of a dynamical ( four - body ) model to compute transit ephemerides for the system .
our photometric data have been collected from published archival sources , as well as from our photometric campaigns that were targeted to specific transit predictions .
our analysis indicates that transits by planet `` c '' ( @xmath0 ) do not currently occur , in concordance with the best - fit @xmath2 co - planar configuration obtained by dynamical fits to the most recent radial velocity data for the system .
transits by planet `` b '' ( @xmath3 ) are not entirely ruled out by our observations , but our data indicate that it is very unlikely that they occur .
our experience with the gl 876 system suggests that a distributed ground - based network of small telescopes can be used to search for transits of very low mass m - stars by terrestrial - sized planets . .
And you have already written the first three sentences of the full article: the gl 876 planetary system ranks with the most remarkable dicoveries that have emerged from the first decade of extrasolar planet detections . as described by rivera et al .
( 2005 ) , laughlin et al .
( 2005 ) , butler et al ..
Please generate the next two sentences of the article | ( 2001 ) marcy et al .
( 2001 ) , delfosse et al . |
7,604 | Suppose that you have an abstract for a scientific paper: we study general conditions for the gravitino to be the lightest supersymmetric particle ( lsp ) in models with gravity mediated supersymmetry breaking .
we find that the decisive quantities are the khler potential @xmath0 and the gauge kinetic function @xmath1 . in constrained mssm ( cmssm )
type models , the gravitino lsp occurs if the gaugino mass at the gut scale is greater than approximately 2.5 gravitino masses .
this translates into @xmath2 , where the derivatives are taken with respect to the dominant susy breaking field .
this requirement can easily be satisfied in string - motivated setups .
= 20pt * jrn kersten@xmath3 and oleg lebedev@xmath4 * + @xmath5__university of hamburg , ii .
institute for theoretical physics + luruper chaussee 149 , 22761 hamburg , germany _
_ + @xmath6__desy theory group + notkestrae 85 , 22603 hamburg , germany _ _ .
And you have already written the first three sentences of the full article: it is an exciting possibility that dark matter has a supersymmetric origin .
various species can have the properties of dark matter depending on the supersymmetry breaking mechanism and further particulars of the model , with the neutralino and gravitino being the most prominent candidates . in classes of models like anomaly @xcite and mirage @xcite mediation , the gravitino is heavier than the other sparticles and
thus can not constitute dark matter . on the other hand , in gauge @xcite and gaugino @xcite mediation , the gravitino is light and represents a good candidate for dark matter @xcite,@xcite . in gravity mediation.
Please generate the next two sentences of the article | @xcite , the situation is more model - dependent and both relatively heavy and light gravitinos are possible . in this work ,
we study the circumstances under which the gravitino is the lsp in gravity mediation . if we further require r- or matter parity @xcite , which can descend from string theory @xcite , the gravitino is stable and can constitute dark matter . |
7,605 | Suppose that you have an abstract for a scientific paper: we study the effect of intra - atomic correlations on anisotropies of hopping of 5@xmath0 electrons . it is shown that they may considerably enhance these anisotropies to the extend that electrons in some of the 5@xmath0 orbitals remain localized .
this provide a microscopic basis for a previously made assumption that some of the 5@xmath0 electrons must be partially localized when fermi surfaces and effective masses of the component are calculated .
calculations are performed on two- and three - sites clusters .
they include phase diagrams in the presence and absence of an external magnetic field as function of anisotropic hopping . # 1 # 1 1 .
And you have already written the first three sentences of the full article: systems with strongly correlated electrons are a subject of considerable research efforts . among those are the ones with 5@xmath0 electrons , i. e. , involving actinide ions of particular interest .
while 4@xmath0 electrons , because of their closeness to the nuclei , are correlated as strongly as possible on an atom , the 5@xmath0 electrons have a larger spatial extent and tend more towards delocalization .
the degree of delocalization is even more pronounced when 3@xmath1 electrons are considered . by continuing this line of arguments.
Please generate the next two sentences of the article | one finds that @xmath2 electrons are the least correlated ones on an atom and have the largest tendency to delocalize . returning to 5@xmath0 electrons
, the question arises under which circumstances localized features dominate delocalized ones or vice versa . |
7,606 | Suppose that you have an abstract for a scientific paper: by removing one empty site between two occupied sites , we map the ground states of chains of hardcore bosons and spinless fermions with infinite nearest - neighbor repulsion to ground states of chains of hardcore bosons and spinless fermions without nearest - neighbor repulsion respectively , and ultimately in terms of the one - dimensional fermi sea .
we then introduce the intervening - particle expansion , where we write correlation functions in such ground states as a systematic sum over conditional expectations , each of which can be ultimately mapped to a one - dimensional fermi - sea expectation .
various ground - state correlation functions are calculated for the bosonic and fermionic chains with infinite nearest - neighbor repulsion , as well as for a ladder model of spinless fermions with infinite nearest - neighbor repulsion and correlated hopping in three limiting cases .
we find that the decay of these correlation functions are governed by surprising power - law exponents . .
And you have already written the first three sentences of the full article: exact solutions hold a special place in the theoretical condensed matter physics of interacting electron systems .
although they can be obtained only for very specific models , these proved to be very useful in understanding the behaviour of more general models of interacting electrons , or informing us of novel physics that we would otherwise not suspect from approximate treatments . in particular , our present paradigm of two universality classes , fermi liquids versus luttinger liquids , for low - dimensional systems of interacting fermions came out of exact solutions showing separation of the charge and spin degrees of freedom @xcite . in this paper , we report further surprises coming out of the exact solution of models of hardcore bosons and spinless fermions with infinite nearest - neighbor repulsion @xcite .
we consider chain models @xmath0 + u\sum_j n_j ( n_j - { \mathbb{1 } } ) \\ & \quad\ + \expandafter v\sum_j n_j n_{j+1 } , \\.
Please generate the next two sentences of the article | h_{tv}^{(c , f ) } & = -t\sum_j\left[{c_{j}^{\dagger}}{c_{j+1 } } + { c_{j+1}^{\dagger}}{c_{j}}\right ] + v\sum_j n_j n_{j+1 } , \end{aligned}\ ] ] of hardcore bosons ( @xmath1 ) and spinless fermions , as well as a ladder model @xmath2 of spinless fermions . in this ladder model@xcite ,
the correlated hopping @xmath3 is the simplest term we can introduce to blatantly favor the emergence of superconducting order . throughout this paper |
7,607 | Suppose that you have an abstract for a scientific paper: we present the results of the monitoring of the grb 970111 field that started 19 hours after the event .
this observation represents the fastest ground - based follow - up performed for grb 970111 in all wavelengths .
as soon as the detection of the possible grb 970111 x - ray afterglow was reported by feroci et al .
( 1998 ) we reanalyzed the optical data collected for the grb 970111 field .
although we detect small magnitude variability in some objects , no convincing optical counterpart is found inside the wfc error box . any change in brightness 19 hours after the grb is less than 0.2 mag for objects with b @xmath0 21 and r @xmath0 20.8 .
the bluest object found in the field is coincident with 1sax j1528.8 + 1937 .
spectroscopic observations revealed that this object is a seyfert-1 galaxy with redshift @xmath1 , which we propose as the optical counterpart of the x - ray source .
further observations allowed to perform multicolour photometry for objects in the grb 970111 error box .
the colour - colour diagrams do not show any object with unusual colours .
we applied a photometric classification method to the objects inside the grb error box , that can distinguish stars from galaxies and estimate redshifts .
we were able to estimate photometric redshifts in the range @xmath2 for several galaxies in this field and we did not find any conspicuous unusual object .
we note that grb 970111 and grb 980329 could belong to the same class of grbs , which may be related to nearby sources ( @xmath3 ) in which high intrinsic absorption leads to faint optical afterglows . .
And you have already written the first three sentences of the full article: gamma - ray bursts ( grbs ) are powerful brief transient phenomena of high - energy radiation that appear randomly in the sky .
they were first detected in 1969 by the _
vela _ satellites ( klebesadel et al . 1973 ) and have remained for many years one of the most elusive mysteries in astrophysics . before the launch of the _ bepposax _ and _ rossixte _ satellites in 1996.
Please generate the next two sentences of the article | , they had not been detected in any other wavelength region , and their distance scale remained unknown .
the discovery of x - ray afterglows by both satellites revolutionized the field , because they are able to provide very accurate grb error boxes within a few hours ( circular error boxes with radius up to @xmath4 ) , which enables very rapid follow up observations at longer wavelengths . |
7,608 | Suppose that you have an abstract for a scientific paper: in this work , we investigate the one - loop qcd correction to top pair production in the littlest higgs model with t - parity at the lhc .
we calculate the relative correction of the top pair production cross section and top - antitop spin correlation at the lhc for @xmath0 tev .
we find that the relative corrections of top pair production cross section can reach about @xmath1 , and the top - antitop spin correlation can reach @xmath2(@xmath3 ) at the 8(14 ) tev lhc in the favorable parameter space . .
And you have already written the first three sentences of the full article: since the top quark was discovered at the fermilab tevatron in 1995@xcite , it has always been one of the hottest topics in particle physics .
so far , the top quark is the heaviest particle discovered , with a mass close to the electroweak symmetry breaking scale .
thus it is a wonderful probe for the electroweak breaking mechanism and new physics ( np ) beyond the standard model ( sm ) . as a genuine top quark factory.
Please generate the next two sentences of the article | , the lhc will copiously produce the top quark events and can provide a good opportunity to scrutinize the top quark properties . in order to solve the hierarchy problem ,
the little higgs model was proposed @xcite , where the higgs boson is constructed as a pseudo - goldstone boson . |
7,609 | Suppose that you have an abstract for a scientific paper: we show that space - based telescopes such as the proposed terrestrial planet finder coronagraph will be able to detect the light scattered by the interstellar grains along lines of sight passing near stars in our galaxy .
the relative flux of the scattered light within one arcsecond of a star at 100 pc in a uniform interstellar medium of 0.1 h atoms @xmath0 is about @xmath1 .
the halo increases in strength with the distance to the star and is unlikely to limit the coronagraphic detection of planets around the nearest stars .
grains passing within 100 au of sun - like stars are deflected by radiation , gravity and magnetic forces , leading to features in the scattered light that can potentially reveal the strength of the stellar wind , the orientation of the stellar magnetic field and the relative motion between the star and the surrounding interstellar medium . .
And you have already written the first three sentences of the full article: scattered starlight is a valuable tool for measuring the properties of interstellar dust . in optical reflection
nebulae @xcite , dark clouds @xcite and the diffuse galactic light @xcite the scattering grains typically lie many arcseconds from the illuminating sources . the dust can be nearer to or further from us than the source and the detected photons have been deflected through a wide range of angles .
further information about interstellar grains comes from stellar x - rays scattered by foreground dust within a few arcseconds of the star @xcite ..
Please generate the next two sentences of the article | the measurements sample the whole column of material between us and the star because the grains are strongly forward scattering at x - ray energies . here
we show that high - contrast imaging with a space - based telescope such as the proposed terrestrial planet finder coronagraph enables a new kind of measurement for probing dust at projected separations similar to the x - ray measurements . |
7,610 | Suppose that you have an abstract for a scientific paper: some aspects of hadron spectroscopy are reviewed as of summer 2005 .
address = enrico fermi institute and department of physics , university of chicago , 5640 s. ellis avenue , chicago il 60637 usa .
And you have already written the first three sentences of the full article: hadron spectroscopy plays a valuable role in particle physics .
it was crucial in validating quantum chromodynamics ( qcd ) and the quark substructure of matter .
it provides a stage for understanding nonperturbative techniques , not only in qcd but potentially elsewhere in physics ..
Please generate the next two sentences of the article | hadron spectra are crucial in separating electroweak physics from strong - interaction effects , as in charm and beauty decays .
quarks and leptons have an intricate level and weak coupling structure for which we have no fundamental understanding . |
7,611 | Suppose that you have an abstract for a scientific paper: iras 19312 + 1950 is a unique sio maser source , exhibiting a rich set of molecular radio lines , although sio maser sources are usually identified as oxygen - rich evolved stars , in which chemistry is relatively simple comparing with carbon - rich environments .
the rich chemistry of iras 19312 + 1950 has raised a problem in circumstellar chemistry if this object is really an oxygen - rich evolved star , but its evolutional status is still controversial . in this paper , we briefly review the previous observations of iras 19312 + 1950 , as well as presenting preliminary results of recent vlbi observations in maser lines .
pdf file of the poster is available from http://www.geocities.jp/nakashima_junichi/ .
And you have already written the first three sentences of the full article: sio maser sources are usually identified as oxygen - rich ( o - rich ) evolved stars , and it has been long thought that o - rich evolved stars do not significantly contribute to the enrichment of organic matter in the universe unlike carbon stars do .
however , recent observations of iras 19312 + 1950 , which is an sio maser source ( nakashima & deguchi 2000 ) , suggest that o - rich stars are non - negligible in the chemical evolution of the universe , because a rich set of molecular lines are detectable toward iras 19312 + 1950 .
if iras 19312 + 1950 is really an o - rich evolved star , its chemical properties are quite suggestive in terms of the interstellar chemistry , but we must securely identify its evolved - star status before going to further astrophysical / astrochemical interpretation , because some observational properties of this object are not consistent with the evolved - star status ..
Please generate the next two sentences of the article | the extended infrared nebulosity of iras 19312 + 1950 was first realized in the 2mass images by nakashima & deguchi ( 2000 ) , and soon after that a more fine near - infrared image was obtained by uh 2.2 m / sirius .
the sirius imaging revealed that the envelope of iras 19312 + 1950 exhibits a point symmetric structure . |
7,612 | Suppose that you have an abstract for a scientific paper: a model of directed percolation processes with colors and flavors that is equivalent to a population model with many species near their extinction thresholds is presented .
we use renormalized field theory and demonstrate that all renormalizations needed for the calculation of the universal scaling behavior near the multicritical point can be gained from the one - species gribov process ( reggeon field theory ) . in addition
this universal model shows an instability that generically leads to a total asymmetry between each pair of species of a cooperative society , and finally to unidirectionality of the interspecies couplings .
it is shown that in general the universal multicritical properties of unidirectionally coupled directed percolation processes with linear coupling can also be described by the model .
consequently the crossover exponent describing the scaling of the linear coupling parameters is given by @xmath0 to all orders of the perturbation expansion .
as an example of unidirectionally coupled directed percolation , we discuss the population dynamics of the tournaments of three colors .
key words : multicolored directed percolation , field - theoretic renormalization group , stochastic population dynamics , .
And you have already written the first three sentences of the full article: nonequilibrium processes , their stationary states and their phase transitions have been of considerable interest in natural science as well as in medicine and sociology for many years .
here we are interested in processes that can be modelled by growth and decay of populations with spatially local interaction rules .
the transition between survival and extinction of a population is a nonequilibrium continuous phase transition phenomenon and is characterized by universal scaling laws ..
Please generate the next two sentences of the article | it is well known that also for systems far from equilibrium the concept of universality classes with respect to their critical properties in the vicinity of a continuous phase transition is applicable . for the description of transitions in systems that show active and absorbing inactive states , percolation models play an outstanding role .
some years ago it was conjectured @xcite that markovian growth models with one - component order parameters displaying a transition into an absorbing state in the absence of any special conservation law generically belong to the universality class of directed percolation ( dp ) . |
7,613 | Suppose that you have an abstract for a scientific paper: the origin of radio emission from plerions is considered .
recent observations suggest that radio emitting electrons are presently accelerated rather than having been injected at early stages of the plerion evolution .
the observed flat spectra without a low frequency cutoff imply an acceleration mechanism that raises the average particle energy by orders of magnitude but leaves most of the particles at the energy less than about few hundred mev .
it is suggested that annihilation of the alternating magnetic field at the pulsar wind termination shock provides the necessary mechanism .
toroidal stripes of opposite magnetic polarity are formed in the wind emanated from an obliquely rotating pulsar magnetosphere ( the striped wind ) . at the termination shock , the flow compresses and the magnetic field annihilates by driven reconnection .
jump conditions are obtained for the shock in a striped wind .
it is shown that postshock mhd parameters of the flow are the same as if the energy of alternating field has already been converted into the plasma energy upstream the shock .
therefore the available estimates of the ratio of the poynting flux to the matter energy flux , @xmath0 , should be attributed not to the total upstream poynting flux but only to that associated with the average magnetic field .
a simple model for the particle acceleration in the shocked striped wind is presented .
acceleration of particles magnetic fields mhd shock waves pulsars : general supernova remnants .
And you have already written the first three sentences of the full article: most of the pulsar spin - down power is carried away by a relativistic , magnetized wind .
the pulsar wind injects this energy into the surrounding nebula in the form of relativistic electron - positron pairs and magnetic fields therefore such nebulae , or plerions , emit synchrotron radiation from the radio to the gamma - ray band .
the most famous and well studied example of the plerion is the crab nebula ; the spectrum of this source is measured from about 10 mhz to dozens tev . according to mhd models ( rees & gunn 1974 ; kennel & coroniti 1984 ; emmering & chevalier 1987 ; begelman & li 1992 ) , the pulsar wind terminates in a standing shock at a radius defined by the condition that the confining pressure balances the momentum flux of the wind . in the crab case ,.
Please generate the next two sentences of the article | the shock radius was estimated to be @xmath1 cm in excellent agreement with observations ; according to chandra results ( weisskopf et al .
2000 ) , the radius of the shock in the equatorial plane is @xmath2 cm . the observed brightness and the spectral index distributions are generally consistent with the assumption that the relativistic particles are accelerated at the termination shock and then fill in the nebula , spending the acquired energy on synchrotron emission and @xmath3 work . |
7,614 | Suppose that you have an abstract for a scientific paper: a planar force - constant model is developed for longitudinal phonons of wurtzite gan and aln propagating along the [ 0001 ] direction .
the proposed model is then applied to the study of the phonon modes in hexagonal ( 0001)-gan / aln supperlattices in longitudinal polarization .
the confinement of the superlattice phonon modes is discussed . .
And you have already written the first three sentences of the full article: among the iii - v semiconductors the nitride - based semiconductors have received both scientific and technological attention over the past years owing to their excellent physical properties.@xcite the fascinating mechanical properties , such as hardness , high melting temperature , high thermal conductivity , and large bulk moduli make them useful for protective coatings . in particular , the electronic properties , characterized by large band gaps and relatively low dielectric constants , indicate tremendous potential applications in optical devices working in the blue and ultraviolet ( uv ) wavelengths .
recently , high - power blue and green light emitting diodes ( leds ) have been fabricated by using ingan - based multiquantum - well structures and are commercially available .
@xcite blue and uv nitride semiconductor laser diodes ( lds ) have also successfully been demonstrated ..
Please generate the next two sentences of the article | @xcite consequently there has been great interest in the fundamental properties , the understanding of which can render the improvement of the materials and device quality possible .
heterostructures based on gan and ga@xmath0al@xmath1n have become important candidates for optoelectronic materials . |
7,615 | Suppose that you have an abstract for a scientific paper: the lhcb experiment has recently established a sizable width difference between the mass eigenstates of the @xmath0-meson system .
this phenomenon leads to a subtle difference at the 10% level between the experimental branching ratios of @xmath0 decays extracted from time - integrated , untagged data samples and their theoretical counterparts .
measuring the corresponding effective @xmath0-decay lifetimes , both branching ratio concepts can be converted into each other .
the rare decay @xmath1 and the search for new physics through this channel is also affected by this effect , which enhances the standard - model reference value of the branching ratio by @xmath2 , while the effective lifetime offers a new observable to search for physics beyond the standard model that is complementary to the branching ratio .
@xmath0 decays , branching ratios , effective lifetimes , new physics .
And you have already written the first three sentences of the full article: weak decays of @xmath3 mesons encode valuable information about the quark - flavour sector of the standard model ( sm ) of particle physics . the conceptually simplest observables are branching ratios , which describe the probability for the considered decay to occur .
measurements of @xmath0-decay branching ratios at hadron colliders would require precise knowledge of the @xmath0 production cross section , which is not available , and rely therefore on experimental control channels and the ratio of the @xmath4 fragmentation functions ( for a detailed discussion , see ref .
@xcite ) . at the @xmath5 @xmath6 factories operating at the @xmath7 resonance , @xmath0-decay.
Please generate the next two sentences of the article | branching ratios can be extracted since the total number of produced @xmath0 mesons can be determined separately @xcite . the neutral @xmath0 mesons exhibit @xmath3@xmath8 mixing . measuring the time - dependent angular distribution of the @xmath9 decay products @xcite , lhcb has recently established a non - vanishing difference @xmath10 between the decay widths of the @xmath0 mass eigenstates @xcite : @xmath11 where @xmath12 is the inverse of the average @xmath0 lifetime @xmath13 . since a discrete ambiguity
could also be resolved @xcite , we are left with the sign in ( [ ys ] ) , which agrees with the sm expectation . a sizable value of @xmath10 was theoretically expected since decades @xcite . in view of the sizable @xmath10 |
7,616 | Suppose that you have an abstract for a scientific paper: in cognitive radio systems , cyclostationary feature detection plays an important role in spectrum sensing , especially in low snr cases . to configure the detection threshold under a certain noise level and a pre - set miss detection probability @xmath0 , it s important to derive the theoretical distribution of the observation variable . in this paper , noise distribution in cyclic frequency domain has been studied and generalized extreme value ( gev ) distribution is found to be a precise match .
maximum likelihood estimation is applied to estimate the parameters of gev .
monte carlo simulation has been carried out to show that the simulated roc curve is coincided with the theoretical roc curve , which proves the efficiency of the theoretical distribution model . cognitive radio , spectrum sensing , cyclic feature detection , noise distribution on cyclic frequency domain .
And you have already written the first three sentences of the full article: spectrum sensing plays an important role in cognitive radio ( cr ) systems , and cyclostationary feature detection is one of the main technologies for spectrum sensing in low snr cases [ 1 - 2 ] .
the idea of cyclic detection is that one cr node samples the rf signals , transform the time domain signals into cyclic frequency domain , then decide primary user s occupancy of a target band regarding whether the cyclic spectrum on a significant cyclic frequency is above a certain threshold [ 2 ] .
+ although the simulation results of cyclostationary feature detection has been studied [ 3 - 5 ] , less attention has been paid to analyze the noise distribution on cyclic frequency domain . consequently , theoretical function between detection threshold @xmath1 and miss detection probability @xmath0 is not available , which makes it difficult for practical system design . for comparison , the theoretical function between detection threshold @xmath1 and miss detection probability @xmath0 of energy detection is available by using central and non - central chi - square distribution to model the distribution of the observation variable affected by time domain gaussian noise [ 6 ] , which makes energy detection to be a practical method for spectrum sensing ..
Please generate the next two sentences of the article | however , its performance in low snr cases is much poorer than cyclostationary feature detection [ 7 ] . in this paper ,
noise distribution on cyclic frequency domain has been analyzed and generalized extreme value distribution is found to be a precise match of the observation variable affected by time domain gaussian noise . a fast cyclic frequency domain feature detection algorithm [ 7 ] has been introduced to evaluate the coincidence between theoretical roc curve and the simulated roc curve , which proves the reliability of theoretical distribution model and feasibility of practical system design . |
7,617 | Suppose that you have an abstract for a scientific paper: we have used a fourier transform spectrometer on the james clerk maxwell telescope to study the submillimetre continuum emission from dust in three hot molecular cores ( hmc ) .
the spectral index @xmath0 of the dust emission for these sources has been determined solely within the 30ghz wide 350ghz ( 850 ) passband to an accuracy comparable to those determined through multi - wavelength observations .
we find an average @xmath1 , in agreement with spectral indices determined from previous submillimetre observations of these sources and with those determined for hmc in general .
the largest single source of uncertainty in these results is the variability of the atmosphere at 350ghz , and with better sky subtraction techniques we show that the dust spectral index can clearly be determined within one passband to high accuracy with a submillimetre fts . using an imaging fts on scuba-2 , the next generation wide - field submillimetre camera currently under development to replace scuba at the jcmt in 2006 , we calculate that at 350ghz it will be possible to determine @xmath0 to @xmath2 for sources as faint as 400mjy / beam and to @xmath3 for sources as faint as 140mjy / beam .
[ firstpage ] dust instrumentation : spectrographs stars : formation submillimetre .
And you have already written the first three sentences of the full article: stars form in dense cores of dust and gas within molecular clouds , but remain cocooned in the material of their natal envelopes .
though young stars and protostars can be extremely luminous , the enveloping dust absorbs nearly all of the ultraviolet and optical starlight and reradiates it at longer wavelengths . in the submillimetre regime , the dust emission is generally optically thin .
submillimetre observations thus sample all the dust emission within the cloud along the line of sight , and can be used to determine the column density and mass of material present @xcite ..
Please generate the next two sentences of the article | interpretation of the observations , however , depends on the assumed dust grain temperature , composition and size distribution .
the effects of composition and grain size on the dust emission are usually combined into a dust opacity , @xmath4 , which can be reasonably fit empirically with a power law dependence on frequency in the submillimetre . [ cols="^,^,^,^,^,^ " , ] source brightnesses required to determine the dust spectral index @xmath5 in 12 hours of observing using an ifts on scuba-2 . |
7,618 | Suppose that you have an abstract for a scientific paper: we present the theory of bosonic systems with multiple condensates , unifying disparate models which are found in the literature , and discuss how degeneracies , interactions , and symmetries conspire to give rise to this unusual behavior .
we show that as degeneracies multiply , so do the types of fragmentation , eventually leading to strongly correlated states with no trace of condensation . .
And you have already written the first three sentences of the full article: bose - einstein condensation ( bec ) is a very robust phenomenon . because of bose statistics , non - interacting bosons seek out the lowest single particle energy state and ( below a critical temperature @xmath0 ) condense into it , even though many almost degenerate states may be nearby . at temperature @xmath1
, the condensate contains all the particles in the system @xcite .
although this remarkable phenomenon was originally predicted by einstein for non - interacting systems @xcite , it became understood , starting with the work of f. london @xcite , that it occurs in strongly interacting systems such as @xmath2he . while interactions remove particles from the condensate into other states , the energy gain by macroscopically occupying the lowest energy state ( or another state , such as a vortex ) is sufficiently great that the interactions in a bose condensed system manage only to deplete a fraction of the condensate , but not destroy it @xcite ..
Please generate the next two sentences of the article | this is the case for liquid @xmath2he @xcite as well as dilute gases of bosonic alkali atoms @xcite . in certain situations ,
however , a system does not condense into a _ |
7,619 | Suppose that you have an abstract for a scientific paper: in light of the growing interest in agent - based market models , we bring together several earlier works in which we considered the topic of self - consistent market modelling . building upon the binary game structure of challet and zhang , we discuss generalizations of the strategy reward scheme such that the agents seek to maximize their wealth in a more direct way .
we then examine a disturbing feature whereby such reward schemes , while appearing microscopically acceptable , lead to unrealistic market dynamics ( e.g. instabilities ) . finally , we discuss various mechanisms which are responsible for re - stabilizing the market in reality .
this discussion leads to a ` toolbox ' of processes from which , we believe , successful market models can be constructed in the future . 0.5 in oxford center for computational finance working paper : _ occf/010702 _ .
And you have already written the first three sentences of the full article: agent - based models have attracted significant interest across a broad range of disciplines @xcite .
an increasingly popular application of these models has been the study of financial markets @xcite .
the motivations for this focus on financial markets are two - fold : the promise that data - rich financial markets are good candidates for the empirical study of complex systems , and the inadequacy of standard economic models based on the notions of equilibria and rational expectations ..
Please generate the next two sentences of the article | currently many different agent - based models exist in the econophysics literature , each with its own set of implicit assumptions and interesting properties @xcite . in general
these models manage to exhibit some of the statistical properties that are reminiscent of those observed in real - world financial markets ; for example , fat - tailed distributions of returns and long - timescale volatility correlations . despite their differences , these models draw on several of the same key ideas : feedback , frustration , adaptability and evolution . |
7,620 | Suppose that you have an abstract for a scientific paper: we consider the low - temperature @xmath0 disorder - dominated phase of the directed polymer in a random potentiel in dimension @xmath1 ( where @xmath2 ) and @xmath3 ( where @xmath4 ) . to characterize the localization properties of the polymer of length @xmath5 , we analyse the statistics of the weights @xmath6 of the last monomer as follows .
we numerically compute the probability distributions @xmath7 of the maximal weight @xmath8 $ ] , the probability distribution @xmath9 of the parameter @xmath10 as well as the average values of the higher order moments @xmath11 .
we find that there exists a temperature @xmath12 such that ( i ) for @xmath13 , the distributions @xmath7 and @xmath9 present the characteristic derrida - flyvbjerg singularities at @xmath14 and @xmath15 for @xmath16 . in particular , there exists a temperature - dependent exponent @xmath17 that governs the main singularities @xmath18 and @xmath19 as well as the power - law decay of the moments @xmath20 .
the exponent @xmath17 grows from the value @xmath21 up to @xmath22 .
( ii ) for @xmath23 , the distribution @xmath7 vanishes at some value @xmath24 , and accordingly the moments @xmath25 decay exponentially as @xmath26 in @xmath27 .
the histograms of spatial correlations also display derrida - flyvbjerg singularities for @xmath13 . both below and above @xmath28 ,
the study of typical and averaged correlations is in full agreement with the droplet scaling theory .
# 1#2 # 1#2 .
And you have already written the first three sentences of the full article: a convenient way to characterize disorder - dominated phases is through the statistics of some appropriate `` weights '' . in mean - field models , these weights represent either weights of pure states , as in the replica analysis of the sherrington - kirkpatrick model @xcite , or weights of microscopic configurations , as in the random energy model @xcite or in the directed polymer model on the cayley tree @xcite .
it turns out that in these three cases , the weights statistics is the same as in lvy sums with some index @xmath29 @xcite , where the index @xmath30 depends on the temperature : for instance in the random energy model @xcite or in the directed polymer model on the cayley tree @xcite , it is simply @xmath31 . in @xcite , the corresponding probability distributions of the weights were found to exhibit characteristic singularities at some integer inverses .
similar derrida - flyvbjerg singularities also occur in many other contexts , such as randomly broken objects @xcite , in population genetics @xcite , in random walk excursions or loops @xcite . for disordered systems in finite dimensions.
Please generate the next two sentences of the article | , it seems appropriate to consider the weights associated to a local degree of freedom , to characterize to what extent it is frozen . to the best of our knowledge
, this idea has first been introduced to characterize the freezing of a folded polymer with random self - interactions @xcite . |
7,621 | Suppose that you have an abstract for a scientific paper: the population of compact binaries in dense stellar systems is affected strongly by frequent dynamical interactions between stars and their interplay with the stellar evolution . in this contribution , we consider these effects on binaries with a white dwarf accretor , in particular cataclysmic variables and am cvns . we examine which processes
can successfully lead to the creation of such x - ray binaries . using numerical simulations ,
we identify predominant formation channels and predict the expected numbers of detectable systems .
we discuss also why the distribution of cataclysmic variables has a weaker dependence upon the cluster density than the distribution of quiescent low - mass x - ray binaries and why dwarf nova outbursts may not occur among globular cluster cataclysmic variables .
address = department of physics and astronomy , 2145 sheridan rd , evanston , il 60208 , usa address = department of physics and astronomy , 2145 sheridan rd , evanston , il 60208 , usa .
And you have already written the first three sentences of the full article: in the past few years , substantial progress has been made in optical identification of _ hubble space telescope _
counterparts to _ chandra _ x - ray sources in several globular clusters ( gcs ) .
valuable information was obtained for the population of cataclysmic variables ( cvs ) , chromospherically active binaries and quiescent low - mass x - ray binaries ( qlmxbs ) ( edmonds et al ..
Please generate the next two sentences of the article | 2004 , heinke et al .
2003b , haggard et al . 2004 ) . |
7,622 | Suppose that you have an abstract for a scientific paper: quantum - cryptography key distribution ( qckd ) experiments have been recently reported using polarization - entangled photons . however , in any practical realization , quantum systems suffer from either unwanted or induced interactions with the environment and the quantum measurement system , showing up as quantum and , ultimately , statistical noise . in this paper , we investigate how ideal polarization entanglement in spontaneous parametric downconversion ( spdc ) suffers quantum noise in its practical implementation as a secure quantum system , yielding errors in the transmitted bit sequence . because all spdc - based qckd schemes rely on the measurement of coincidence to assert the bit transmission between the two parties , we bundle up the overall quantum and statistical noise in an exhaustive model to calculate the accidental coincidences .
this model predicts the quantum - bit error rate and the sifted key and allows comparisons between different security criteria of the hitherto proposed qckd protocols , resulting in an objective assessment of performances and advantages of different systems . .
And you have already written the first three sentences of the full article: quantum cryptography key distribution ( qckd ) is at the moment the most advanced and challenging application of quantum information .
qckd offers the possibility that two remote parties , sender and receiver ( conventionally called alice and bob ) , can exchange a secret random key , called sifted key ( string of qubits ) , to implement a secure encryption / decryption algorithm based on a shared secret key , without the need that the two parties meet . in practical qckd ,
alice and bob use a quantum channel , along which sequences of signals are either sent or measured at random between different bases of orthogonal quantum states ..
Please generate the next two sentences of the article | alice can play the role of either setting randomly the polarization basis of photons and sending them to bob ( faint laser pulses as photon source ) , or measuring photons randomly in any one of the selected bases ( entangled photon source ) .
bob , randomly and independently from alice , measures in one of the bases . |
7,623 | Suppose that you have an abstract for a scientific paper: light rays from a multiply imaged quasar usually sample different path lengths across the deflector .
extinction in the lensing galaxy may thus lead to a differential obscuration and reddening between the observed macro - lensed qso images .
these effects naturally depend on the precise shape of the extinction law and on the redshift of the lens . by means of numerical monte - carlo simulations , using a least - squares fitting method and assuming an extinction law similar to that observed in the galaxy , we show how accurate photometric observations of multiply imaged quasars obtained in several spectral bands could lead to the estimate of the lens redshift , irrespective of the visibility of the deflector .
observational requirements necessary to apply this method to real cases are thoroughly discussed .
if extinction laws turn out to be too different from galaxy to galaxy , we find out that more promising observations should consist in getting high signal - to - noise low resolution spectra of at least three distinct images of a lensed quasar , over a spectral range as wide as possible , from which it should be straightforward to extract the precise shape of the redshifted extinction law . very high
signal - to - noise , low spectral resolution , vlt observations of and should enable one to derive such a redshifted extinction law . .
And you have already written the first three sentences of the full article: for the case of several known gravitational lens systems , the deflector is either not yet detected or it is so faint that its redshift remains unknown ( see the gravitational lensing web page at ` http://vela.astro.ulg.ac.be/grav_lens/ ` ) .
measurement of the deflector redshift is mandatory in order to properly model the corresponding gravitational lens systems .
usually , the lens redshift is determined from spectroscopic observations of either emission lines due to the lensing galaxy or of galaxy absorption lines detected in the spectra of the qso images . in this work ,.
Please generate the next two sentences of the article | we present an alternate method to derive the redshift of a too faint and/or an invisible lens .
first , we describe the method which is based upon the fitting of photometric observations with a redshifted extinction model and we then show results from monte carlo simulations . |
7,624 | Suppose that you have an abstract for a scientific paper: this document presents recent results of inclusive top - quark pair production cross section measurements at @xmath0 and @xmath1 .
the results are obtained analyzing the data collected by the cms and atlas detectors at the lhc accelerator .
studies are performed in the dilepton channel , where the smallest uncertainty is reached , with different approaches .
the most precise results of both experiments are combined and confronted with the most precise theoretical calculation ( nnlo - nnll ) . .
And you have already written the first three sentences of the full article: the top quark , the heaviest fundamental particle with a mass about @xmath2 @xcite , plays an important role in the study of the electroweak symmetry breaking ( higgs boson ) as well as in the search of physics beyond the standard model ( bsm ) .
moreover , the production of top quark anti - quark pairs is one of the main backgrounds in many of the processes related with the standard model ( sm ) and bsm , and it is crucial to measure its production cross section with very high precision . the large hadron collider ( lhc ) has been in operation since 2009 , producing proton - proton collisions with a center of mass energy of @xmath3 until 2011 and @xmath1 in 2012 .
this document presents the most recent measurements of the inclusive @xmath4 cross section with data collected using the atlas @xcite and the cms @xcite detectors ..
Please generate the next two sentences of the article | the most recent theoretical predictions for the top quark pair production cross section ( @xmath5 ) are @xmath6 and @xmath7 @xcite for a top - quark mass of @xmath8 . according to the sm , top quarks decay into a w boson and a b quark almost 100% of the times .
this leads to final states with two w bosons and two jets coming from the b quark fragmentation . when both w bosons decay leptonically , the event contains two high momentum leptons with opposite charge , two undetected neutrinos which are measured as missing energy in the plane transverse to the beam axis ( @xmath9 ) , and at least two jets , where two of them originate from b quarks . |
7,625 | Suppose that you have an abstract for a scientific paper: it is shown how to apply the maximum entropy method ( mem ) to numerical dyson - schwinger studies for the extraction of spectral functions of correlators from their corresponding euclidean propagators .
differences to the application in lattice qcd are emphasized and , as an example , the spectral functions of massless quarks in cold and dense matter are presented .
maximum entropy method , dyson - schwinger equations .
And you have already written the first three sentences of the full article: for the investigation of qcd in the strongly coupled regime , non - perturbative numerical methods such as lattice qcd and truncated dyson - schwinger equations can be employed .
similar to lattice qcd , numerical dyson - schwinger studies of qcd n - point functions are usually performed in euclidean space ( for recent reviews see @xcite ) .
although dyson - schwinger studies rely on truncation schemes , they have the great advantage , that they can in principle be solved in the continuum limit and with much higher numerical accuracy ..
Please generate the next two sentences of the article | an extraction of dynamical properties , in particular the spectral functions of propagators , is however highly desirable . in quantum monte carlo simulations , the maximum entropy method ( mem )
turns out to be an especially suited tool and has been successfully applied in condensed matter physics ( see @xcite for a review ) , lattice qcd in the vacuum ( see @xcite for a review ) , as well as at finite temperatures @xcite . in this work |
7,626 | Suppose that you have an abstract for a scientific paper: we analyze the physical properties of post - starburst agn sdssj085338.27 + 033246.1 according to its optical spectrum and discuss its implications on agn s evolution .
the spectra pca method is developed to extract emission lines and absorption features from the total light spectrum .
the emission - line analysis indicates that the object can be classified as a nls1 with feii / h@xmath0 , large eddington ratio ( @xmath1 ) , small black hole mass ( @xmath2 ) and intermediately strong radio emission .
a simple ssp model indicates that the absorption features are reproduced by a @xmath3100 myr old starburst with a mass of @xmath4 rather well .
the current sfr @xmath5 inferred from the [ oii ] emission is much smaller than the past average sfr@xmath6 , however .
the line ratio diagnosis using the bpt diagrams indicates that the narrow emission lines are almost entirely emitted from hii regions .
we further discuss a possible evolutionary path that links agn and starburst phenomena . .
And you have already written the first three sentences of the full article: in recent years , accumulating evidence supports the hypothesis that agn reflects an important stage of galaxy formation .
observations reveals the fact that agn activity and star formation frequently occur together ( e.g. , cid fernandes et al .
2001 ; kauffmann et al . 2003.
Please generate the next two sentences of the article | ; see reviews in gonzalez delgado 2002 ) .
an important clue of co - evolution of agn and starburst is the fundamental , tight relationship between mass of supermassive black hole ( smbh ) and the velocity dispersion of bulge where the smbh resides in ( e.g. , magorrian et al . |
7,627 | Suppose that you have an abstract for a scientific paper: the jordan - wigner transformation is known as a powerful tool in condensed matter theory , especially in the theory of low - dimensional quantum spin systems .
the aim of this chapter is to review the application of the jordan - wigner fermionization technique for calculating dynamic quantities of low - dimensional quantum spin models . after a brief introduction of the jordan - wigner transformation for one - dimensional spin one - half systems and some of its extensions for higher dimensions and higher spin values we focus on the dynamic properties of several low - dimensional quantum spin models .
we start from the famous @xmath0 @xmath1 chain . as a first step we recall well - known results for dynamics of the @xmath2-spin - component fluctuation operator and then turn to the dynamics of the dimer and trimer fluctuation operators .
the dynamics of the trimer fluctuations involves both the two - fermion ( one particle and one hole ) and the four - fermion ( two particles and two holes ) excitations .
we discuss some properties of the two - fermion and four - fermion excitation continua .
the four - fermion dynamic quantities are of intermediate complexity between simple two - fermion ( like the @xmath3 dynamic structure factor ) and enormously complex multi - fermion ( like the @xmath4 or @xmath5 dynamic structure factors ) dynamic quantities .
further we discuss the effects of dimerization , anisotropy of @xmath6 interaction , and additional dzyaloshinskii - moriya interaction on various dynamic quantities .
finally we consider the dynamic transverse spin structure factor @xmath7 for the @xmath0 @xmath1 model on a spatially anisotropic square lattice which allows one to trace a one - to - two - dimensional crossover in dynamic quantities . .
And you have already written the first three sentences of the full article: the subject of quantum magnetism dates back to 1920s .
e. ising@xcite suggested a simplest model of a magnet as a collection of @xmath8 spins which may acquire two values @xmath9 and interact with nearest neighbors on a lattice as @xmath10 and with an external magnetic field as @xmath11 .
to explain the properties of the model we have to calculate the partition function @xmath12 which yields the helmholtz free energy per site @xmath13 ( in what follows we set @xmath14 to simplify the notations ) . in one dimension.
Please generate the next two sentences of the article | the problem was solved by e. ising .
later l. onsager solved the square - lattice ising model@xcite and we know the solution in two dimensions@xcite . |
7,628 | Suppose that you have an abstract for a scientific paper: we study a mathematical model for ocular dominance patterns ( odps ) in primary visual cortex . this model is based on the premise that odp is an adaptation to minimize the length of intra - cortical wiring .
thus we attempt to understand the existing odps by solving a wire length minimization problem .
we divide all the neurons into two classes : left- and right - eye dominated .
we find that segregation of neurons into monocular regions reduces wire length if the number of connections to the neurons of the same class ( intraocular ) differs from the number of interocular connections .
the shape of the regions depends on the relative fraction of neurons in the two classes .
we find that if both classes are almost equally represented , the optimal odp consists of interdigitating stripes . if one class is less numerous than the other , the optimal odp consists of patches of the less abundant class surrounded by the neurons of the other class .
we predict that the transition from stripes to patches occurs when the fraction of neurons dominated by the underrepresented eye is about @xmath0 .
this prediction agrees with the data in macaque and cebus monkeys .
we also study the dependence of the periodicity of odp on the parameters of our model . .
And you have already written the first three sentences of the full article: in the primary visual area ( v1 ) of many mammals , most neurons respond to the stimulation of two eyes unevenly : they are either right or left eye dominated . in some species ,
right / left eye dominated neurons are segregated and form a system of alternating monocular regions known as the ocular dominance pattern ( odp ) ( wiesel and hubel , 1965 , 1969 ) . in others ,
odp is not observed ( see horton and hocking , 1996b for a comprehensive list of species ) ..
Please generate the next two sentences of the article | odps , when observed , vary significantly between different species and even between different parts of v1 in the same animal .
most modeling studies of odp ( erwin et al . , 1995 ; |
7,629 | Suppose that you have an abstract for a scientific paper: x 1908 + 075 is an optically unidentified and highly absorbed x - ray source that appears in early surveys such as uhuru , oso-7 , ariel v , heao-1 , and the exosat galactic plane survey .
these surveys measured a source intensity in the range of 212 mcrab at 210 kev , and the position was localized to @xmath0 .
we use the rossi x - ray timing explorer ( _ rxte _ ) all sky monitor ( asm ) to confirm our expectation that a particular einstein ipc detection ( 1e 1908.4 + 0730 ) provides the correct position for x 1908 + 075 .
the analysis of the coded mask shadows from the asm for the position of 1e 1908.4 + 0730 yields a persistent intensity @xmath1 mcrab ( 1.512 kev ) over a 3 year interval beginning in 1996 february .
furthermore , we detect a period of 4.400 @xmath2 0.001 days with a false alarm probability @xmath3 .
the folded light curve is roughly sinusoidal , with an amplitude that is 22% of the mean flux .
the x - ray period may be attributed to the scattering and absorption of x - rays through a stellar wind combined with the orbital motion in a binary system .
we suggest that x 1908 + 075 is an x - ray binary with a high mass companion star . .
And you have already written the first three sentences of the full article: x - ray surveys have consistently indicated the existence of a moderately bright x - ray source near the galactic longitude 41.97@xmath4 and latitude @xmath5 . this source , which we refer to as x 1908 + 075 , was cataloged as 4u 1909 + 07 by uhuru , the first earth - orbiting mission dedicated to celestial x - ray astronomy ( forman et al .
subsequent determinations were cataloged as 1 m 1912 + 077 with mit / oso 7 ( markert et al . 1979 ) , 3a 1907 + 074 with ariel 5 ( warwick et al .
1981 ; bell burnell & chiappetti 1984 ) , 1h 1907 + 074 with heao a-1/lass ( wood et al ..
Please generate the next two sentences of the article | 1984 ) , gps 1908 + 075 with exosat / me ( warwick et al . 1988 ) .
there are large uncertainties in the position determinations of these survey instruments , as shown in fig . |
7,630 | Suppose that you have an abstract for a scientific paper: the probability of @xmath0-boson decay to a pair of charged fermions in a strong electromagnetic field , @xmath1 , is calculated . on the basis of a method that employs exact solutions to relativistic wave equations for charged particles , an analytic expression for the partial decay width @xmath2
is obtained at an arbitrary value of the parameter @xmath3 , which characterizes the external - field strength . the total @xmath0-boson decay width in an intense electromagnetic field , @xmath4 , is calculated by summing these results over all known generations of charged leptons and quarks .
it is found that , in the region of relatively weak fields ( @xmath5 ) , the field - induced corrections to the standard @xmath0-boson decay width in a vacuum do not exceed 2% . as @xmath6 increases , the total decay width @xmath4 develops oscillations against the background of its gradual decrease to the absolute - minimum point . at @xmath7 ,
the total @xmath0-boson decay width reaches the minimum value of @xmath8 gev , which is smaller than the @xmath0-boson decay width in a vacuum by more than 10% . in the region of superstrong fields ( @xmath9 )
, @xmath4 grows monotonically with increasing external - field strength . in the region @xmath10 , the @xmath11-quark - production process @xmath12 , which is forbidden in the absence of an external field , begins contributing significantly to the total decay width of the @xmath0- boson . .
And you have already written the first three sentences of the full article: it is not an exaggeration to say that @xmath0-bosons along with their charged partners , @xmath13-bosons , have been at the focus of attention in high - energy physics over more than the past two decades .
the properties of these particles , which are mediators of weak interaction between leptons and quarks , were studied in detail in experiments at the lep and slc electron - positron colliders . in a series of experiments performed between 1989 and 1995 at cern @xcite ,
enormous statistics of observations of @xmath0-boson production and decays were collected . in all , approximately @xmath14 events associated with leptonic modes of @xmath0-boson decay and more than @xmath15 events of transformation of these unstable particles into hadrons were detected ..
Please generate the next two sentences of the article | the results of these investigations made it possible to determine , among other things , the mass of the @xmath0-boson , @xmath16 , and its total decay width , @xmath17 , to an extremely high degree of precision @xcite .
many other parameters of the process @xmath18 were also analyzed both in the vicinity of the @xmath19-resonance and far from it @xcite . |
7,631 | Suppose that you have an abstract for a scientific paper: we have modeled laser - induced transient current waveforms in radiation coplanar grid detectors .
poisson s equation has been solved by finite element method and currents induced by photo - generated charge were obtained using shockley - ramo theorem . the spectral response on a radiation flux
has been modeled by monte - carlo simulations .
we show 10@xmath0 improved spectral resolution of coplanar grid detector using differential signal sensing .
we model the current waveform dependence on doping , depletion width , diffusion and detector shielding and their mutual dependence is discussed in terms of detector optimization .
the numerical simulations are successfully compared to experimental data and further model simplifications are proposed . the space charge below electrodes and a non - homogeneous electric field on a coplanar grid anode
are found to be the dominant contributions to laser - induced transient current waveforms . .
And you have already written the first three sentences of the full article: high energy radiation can be detected directly by converting photons into electrical signals , or indirectly using scintilators and photodiodes .
direct conversion detectors are expected to have higher signal - to - noise ration , higher spatial and temporal resolution , even on a single photon counting level .
this could lead to spectrally resolved computed tomography and advanced medical x - ray imaging @xcite ..
Please generate the next two sentences of the article | an efficient detector optimization is a challenging technological task .
the single crystal growth is one of them , high mobility - relaxation time product ( @xmath1 ) is another one and least but not the last one is different mobility and trapping cross - section of photo - generated holes . |
7,632 | Suppose that you have an abstract for a scientific paper: solving the exact renormalisation group equation la wilson - polchinski perturbatively , we derive a power - counting theorem for general matrix models with arbitrarily non - local propagators .
the power - counting degree is determined by two scaling dimensions of the cut - off propagator and various topological data of ribbon graphs . as a necessary condition for the renormalisability of a model , the two scaling dimensions have to be large enough relative to the dimension of the underlying space . in
order to have a renormalisable model one needs additional locality properties typically arising from orthogonal polynomials which relate the relevant and marginal interaction coefficients to a finite number of base couplings .
the main application of our power - counting theorem is the renormalisation of field theories on noncommutative @xmath0 in matrix formulation . .
And you have already written the first three sentences of the full article: noncommutative quantum field theories show in most cases a phenomenon called _ uv / ir - mixing _
@xcite which seems to prevent the perturbative renormalisation .
there is an enormous number of articles on this problem , most of them performing one - loop calculations extrapolated to higher order . a systematic analysis of noncommutative ( massive ) field theories at _ any loop order _ was performed by chepelev and roiban @xcite ..
Please generate the next two sentences of the article | they calculated the integral of an arbitrary feynman graph using the parametric integral representation and expressed the result in terms of determinants involving the incidence matrix and the intersection matrix .
they succeeded to evaluate the leading contribution to the determinants in terms of topological properties of _ ribbon graphs _ wrapped around riemann surfaces . in this way a power - counting theorem was established which led to the identification of two power - counting non - renormalisable classes of ribbon graphs . |
7,633 | Suppose that you have an abstract for a scientific paper: we introduce and analyze a class of one dimensional insulating hamiltonians which , when adiabatically varied in an appropriate closed cycle , define a @xmath0 pump " . for an isolated system a single closed cycle of the pump
changes the expectation value of the spin at each end even when spin orbit interactions violate the conservation of spin . a second cycle , however returns the system to its original state .
when coupled to leads , we show that the @xmath0 pump functions as a spin pump in a sense which we define , and transmits a finite , though non quantized spin in each cycle . we show that the @xmath0 pump is characterized by a @xmath0 topological invariant that is analogous to the chern invariant that characterizes a topological charge pump .
the @xmath0 pump is closely related to the quantum spin hall effect , which is characterized by a related @xmath0 invariant .
this work presents an alternative formulation which clarifies both the physical and mathematical meaning of that invariant . a crucial role
is played by time reversal symmetry , and we introduce the concept of the time reversal polarization , which characterizes time reversal invariant hamiltonians and signals the presence or absence of kramers degenerate end states . for non interacting electrons we derive a formula for the time reversal polarization which is analogous to the berry s phase formulation of the charge polarization . for interacting electrons , we show that abelian bosonization provides a simple formulation of the time reversal polarization .
we discuss implications for the quantum spin hall effect , and argue in particular that the @xmath0 classification of the quantum spin hall effect is valid in the presence of electron electron interactions . .
And you have already written the first three sentences of the full article: in recent years , the advent of spintronics has motivated the search for methods of generating spin currents with little or no dissipation .
one class of proposals involves designing an adiabatic pump in which the cyclic variation of some control parameters results in the transfer of spin across an otherwise insulating structure@xcite .
such a spin pump has been realized in quantum dot structures@xcite ..
Please generate the next two sentences of the article | a second class of proposals involves using the spin hall effect to generate a spin current using an electric field @xcite .
interest in this approach has been stimulated by the experimental observation of spin accumulation induced by the spin hall effect in doped gaas structures@xcite . in these experiments |
7,634 | Suppose that you have an abstract for a scientific paper: bepposax and asca observations of the nearby ( z = 0.184 ) , high luminosity , radio - quiet quasar pds 456 are presented .
the x ray spectrum is characterized by a prominent ionized edge at 89 kev ( originally discovered by rxte , reeves et al .
2000 ) and by a soft excess below 1.5 kev .
the lack of any significant iron k@xmath0 emission line suggests for the edge an origin from line of sight material rather than from reflection from a highly ionized accretion disc .
the hard x ray continuum is indeed well modelled by transmission through a highly - ionized medium with a large column density ( @xmath1 4.5 @xmath2 10@xmath3 @xmath4 ) plus an additional cold absorber with a lower column density ( @xmath5 @xmath6 2.7 @xmath2 10@xmath7 @xmath4 ) . .
And you have already written the first three sentences of the full article: the average 210 kev x ray spectrum of low / medium - redshift quasars observed with exosat ( comastri et al .
1992 ; lawson et al . 1992 ) , ginga ( williams et al . 1992 ; lawson & turner 1997 ) and asca ( reeves et al . 1997 ; george et al .
2000 ) is well represented by a power law with a slope similar to that of lower luminosity seyfert 1 galaxies ( @xmath8 1.92.0 , nandra & pounds 1994 ) and significant dispersion around the mean value @xmath9 0.20.3 ..
Please generate the next two sentences of the article | the typical imprints of reprocessing gas ( i.e. the reflection `` hump '' and the k@xmath0 emission line ) , which characterize the spectra of seyfert 1 galaxies ( nandra & pounds 1994 ; nandra et al .
1997 ) are however not present in high luminosity objects . |
7,635 | Suppose that you have an abstract for a scientific paper: recent measurements of the deuteron electromagnetic structure functions @xmath0 , @xmath1 , and
@xmath2 extracted from high energy elastic @xmath3 scattering , and the cross sections and asymmetries extracted from high energy photodisintegration @xmath4 , are reviewed and compared to theory .
the theoretical calculations range from nonrelativistic and relativistic models using the traditional meson and baryon degrees of freedom , to effective field theories , to models based on the underlying quark and gluon degrees of freedom of qcd , including nonperturbative quark cluster models and perturbative qcd .
we review what has been learned from these experiments , and discuss why elastic @xmath3 scattering and photodisintegration seem to require very different theoretical approaches , even though they are closely related experimentally . .
And you have already written the first three sentences of the full article: the deuteron , the only @xmath5 nucleus , provides the simplist microscopic test of the _ conventional nuclear model _ , a framework in which nuclei and nuclear interactions are explained as baryons interacting through the exchange of mesons . with improved nucleon - nucleon force models from the 1990s @xcite , and advances in our understanding of relativistic bound state techniques , more accurate calculations of deuteron structure are possible . during the 1990s
there have also been revolutionary improvements in our experimental knowledge of deuteron electromagnetic structure .
the start of experiments at the thomas jefferson national accelerator facility ( jlab ) has now made available continuous high energy beams , with high currents and large polarization , along with new detector systems ..
Please generate the next two sentences of the article | several experiments have now significantly extended the energy and momentum transfer range of deuteron electromagnetic studies , including @xmath0 and @xmath6 for elastic @xmath3 scattering , and photodisintegration cross sections and polarizations .
existing experimental proposals promise to continue this trend . |
7,636 | Suppose that you have an abstract for a scientific paper: johansen s ( 1988 , 1991 ) likelihood ratio test for cointegration rank of a gaussian var depends only on the squared sample canonical correlations between current changes and past levels of a simple transformation of the data .
we study the asymptotic behavior of the empirical distribution of those squared canonical correlations when the number of observations and the dimensionality of the var diverge to infinity simultaneously and proportionally .
we find that the distribution almost surely weakly converges to the so - called _
wachter distribution_. this finding provides a theoretical explanation for the observed tendency of johansen s test to find spurious cointegration .
it also sheds light on the workings and limitations of the bartlett correction approach to the over - rejection problem .
we propose a simple graphical device , similar to the scree plot , for a preliminary assessment of cointegration in high - dimensional vars . .
And you have already written the first three sentences of the full article: johansen s ( 1988 , 1991 ) likelihood ratio ( lr ) test for cointegration rank is a very popular econometric technique .
however , it is rarely applied to systems of more than three or four variables . on the other hand
, there exist many applications involving much larger systems ..
Please generate the next two sentences of the article | for example , davis ( 2003 ) discusses a possibility of applying the test to the data on seven aggregated and individual commodity prices to test lewbel s ( 1996 ) generalization of the hicks - leontief composite commodity theorem . in a recent study of exchange rate predictability , engel , mark , and west ( 2015 )
contemplate a possibility of determining the cointegration rank of a system of seventeen oecd exchange rates . |
7,637 | Suppose that you have an abstract for a scientific paper: nonequilibrium phase transition properties of a mixed ising ferrimagnetic model consisting of spin-1/2 and spin-3/2 on a square lattice under the existence of a time dependent oscillating magnetic field have been investigated by making use of monte carlo simulations with single - spin flip metropolis algorithm . a complete picture of dynamic phase boundary and magnetization profiles have been illustrated and the conditions of a dynamic compensation behavior have been discussed in detail . according to our simulation results ,
the considered system does not point out a dynamic compensation behavior , when it only includes the nearest - neighbor interaction , single - ion anisotropy and an oscillating magnetic field source . as the next - nearest - neighbor interaction between the spins-1/2 takes into account and
exceeds a characteristic value which sensitively depends upon values of single - ion anisotropy and only of amplitude of external magnetic field , a dynamic compensation behavior occurs in the system .
finally , it is reported that it has not been found any evidence of dynamically first - order phase transition between dynamically ordered and disordered phases , which conflicts with the recently published molecular field investigation , for a wide range of selected system parameters . .
And you have already written the first three sentences of the full article: the phenomenon of ferrimagnetism is related to the counteraction of opposite magnetic moments with unequal magnitudes located on different sublattices .
ferrimagnetic materials have , under certain conditions , a compensation temperature at which the resultant magnetization vanishes below its critical temperature @xcite .
recently , it has been both experimentally and theoretically shown that the coercive field exhibits a rapid increase at the compensation point @xcite ..
Please generate the next two sentences of the article | it is obvious that such kind of point has a technological importance @xcite , because at this point only a small driving field is required to change the sign of the resultant magnetization . due to the recent developments in experimental techniques ,
scientists begin to synthesize new classes of molecular - based magnets @xcite . |
7,638 | Suppose that you have an abstract for a scientific paper: we develop , implement and test a set of algorithms for estimating @xmath0-point correlation functions from pixelized sky maps .
these algorithms are slow , in the sense that they do not break the @xmath1 barrier , and yet , they are fast enough for efficient analysis of data sets up to several hundred thousand pixels .
the typical application of these methods is monte carlo analysis using several thousand realizations , and therefore we organize our programs so that the initialization cost is paid only once .
the effective cost is then reduced to a few additions per pixel multiplet ( pair , triplet etc . ) .
further , the algorithms waste no cpu time on computing undesired geometric configurations , and , finally , the computations are naturally divided into independent parts , allowing for trivial ( i.e. , optimal ) parallelization . .
And you have already written the first three sentences of the full article: since the introduction of correlation functions into modern cosmology by e.g. , totsuji & kihara ( 1969 ) and peebles ( 1973 ) , such functions have proved to be useful in a large variety of situations .
a few typical applications are the study of the distribution of galaxies and clusters of galaxies in the universe ( e.g. , connolly et al .
2002 ; maddox , efstathiou & sutherland 1996 ; dalton et al ..
Please generate the next two sentences of the article | 1994 ; croft , dalton , & efstathiou 1999 ; lilje & efstathiou 1988 ; frieman & gaztaaga 1999 ; jing & brner 1998 ) , the analysis of the gravitational lensing shear ( e.g. , bernardeau , van waerbeke , & mellier 2003 ; takada & jain 2003 ) , or measurements of non - gaussianity in the cosmic microwave background ( e.g. , eriksen , banday , & grski 2002 ; kogut et al .
1996 ) . |
7,639 | Suppose that you have an abstract for a scientific paper: micro - tpc , a time projection chamber ( tpc ) with micro pixel chamber ( @xmath0-pic ) readout was developed for the detection of the three - dimensional fine ( @xmath1 sub - millimeter ) tracks of charged particles .
we developed a two - dimensional position sensitive gaseous detector , or the @xmath0-pic , with the detection area of 10 @xmath2 10 @xmath3 and 65536 anode electrodes of 400 @xmath0 m pitch .
we achieved the gas gain of more than @xmath4 without any other multipliers . with the pipe - line readout system specially developed for the @xmath0-pic , we detected x - rays at the maximum rate of 7.7 mhz .
we developed a micro - tpc with the @xmath0-pic and three - dimensional tracks of electrons were detected with the micro - tpc .
we also developed a prototype of the mev gamma - ray imaging detector which is a hybrid of the micro - tpc and nai ( tl ) scintillator so that we showed that this is a promising method for the mev gamma - ray imaging .
gaseous detector ; time projection chamber ; micro - pattern detector ; gamma - ray imaging .
And you have already written the first three sentences of the full article: of a micro - tpc , a time projection chamber ( tpc ) , which can detect three - dimensional fine tracks of charged particles , has been wanted for years .
we developed the @xmath0-pic , a two - dimensional fine position detector , and a fast readout electronics in order to realize such an `` electric cloud chamber '' . in this paper , the performance of the micro - tpc , together with one example of its applications , is described .
the micro pixel chamber , or the @xmath0-pic , is a pixel type gaseous two - dimensional imaging detector which takes over the outstanding properties of the microstrip gas chamber ( msgc@xcite ) such as the good position resolution and operating capacities under high flux irradiation ..
Please generate the next two sentences of the article | the @xmath0-pic is manufactured by the print circuit board ( pcb ) technology in contrast to an older concept pixel type detector , the microdot chamber@xcite , which is made in the mos technology . with the pcb technology ,
large area detectors can be made cheaply , which is an important feature for developing various kinds of applications . as a consequence of the geometrical properties , discharge problems are less disturbing with @xmath0-pic @xcite , so that stable operations at high gas gain can be realized . |
7,640 | Suppose that you have an abstract for a scientific paper: in the relay based telecommunications with @xmath0 relays between the source and destination , @xmath1 time or frequency slots are required for a single frame transmission . however , without the relays , only one time or frequency slot is used for a single frame transmission . therefore , despite the benefits of relaying systems , this type of communications is not efficient from the spectral efficiency viewpoint .
one solution to reduce this issue might be the full - duplex ( fd ) relays .
an old technique which is reconsidered recently to improve the spectral efficiency of telecommunication systems .
however , fd relays have a certain complexity , so , some similar techniques such as successive relays with nearly the same performance but less complexity is taken into account now .
in successive relaying systems , two relays between the source and destination are employed which receive the transmitted frames from the source and relay it to the destination successively .
this structure generally acts like an fd relays . in this paper , the effective capacity performance of an amplify and forward ( af ) successive relaying systems with power allocation strategy at the relays
are studied perfectly . however , while the inter - rely interference ( iri ) between two successive relays has to be managed well , the power allocation and the effective capacity is derived under different assumptions about the iri . in this way
, we assume weak or strong , short or long - term constraints on the iri .
then we extract the optimal transmitted power at the relay to maximize the effective capacity under these constraints .
example.eps gsave newpath 20 20 moveto 20 220 lineto 220 220 lineto 220 20 lineto closepath 2 setlinewidth gsave .4 setgray fill grestore stroke grestore .
And you have already written the first three sentences of the full article: full - duplex ( fd ) communications is a promising technique which offers to double the spectral efficiency of radio links @xcite .
this impressive capability can response part of the explosive demands for high data - rate services . due to this and despite multiple drawbacks of fd implementation , this technique has been considered as a candidate for next generation 5 g wireless networks @xcite .
in addition , fd can eliminate hidden terminal problem in ad - hoc networks , congestion , and large end - to - end delays @xcite ..
Please generate the next two sentences of the article | therefore , fd communication systems have attracted many attentions in research area recently @xcite-@xcite .
half - duplex ( hd ) and fd are two ways for connecting terminals in a wireless network . |
7,641 | Suppose that you have an abstract for a scientific paper: we report on the study of the linear and circular magneto - gyrotropic photogalvanic effect ( mpge ) in gaas / algaas quantum well structures . using the fact that in such structures the land - factor @xmath0 depends on the quantum well ( qw ) width and has different signs for narrow and wide qws , we succeeded to separate spin and orbital contributions to both mpges .
our experiments show that , for most quantum well widths , the mpges are mainly driven by spin - related mechanisms , which results in a photocurrent proportional to the @xmath0 factor . in structures with a vanishingly small @xmath0 factor , however , linear and circular mpge are also detected , proving the existence of orbital mechanisms . .
And you have already written the first three sentences of the full article: spin and orbital mechanisms , which are present simultaneously in various physical phenomena , result in two competitive contributions in the observable effects .
textbook examples therefore are pauli paramagnetism and landau diamagnetism that yield two comparable contributions to the magnetic susceptibility of an electron gas .
@xcite another bright manifestation is the fine structure of exciton lines in a magnetic field ..
Please generate the next two sentences of the article | @xcite in all these cases , the electron systems are affected by a magnetic field in two different ways : via zeeman splitting of spin sublevels and due to cyclotron twisting of electron trajectories .
an interplay of spin and orbital mechanisms is also expected for linear and circular magneto - gyrotropic photogalvanic effects ( mpge ) . |
7,642 | Suppose that you have an abstract for a scientific paper: in axion quintessence , the cosmological era with an energy contrast in dark energy @xmath0 may represent a significant fraction of the universe s lifetime if the minimum of the axion potential is negative ( unstable axion quintessence ) , thus resolving the cosmic coincidence problem , as pointed out by kallosh , linde , prokushkin , and shmakova .
further details of the evolution of the quintessence field , the scale factor of the universe , and the hubble parameter are presented here , focussing on models with @xmath1 = 0.72 and recent dark energy average equation of state parameter @xmath2 . for these parameter values ,
the contracting universe enters a late time era of kination , the negative hubble parameter acting like a negative friction term in the klein - gordon equation , and the axion field makes many transits of but never remains in its vacuum state .
robust , scaled cosmological equations are derived for simulating the evolution of the scalar field , the scale factor , and the hubble parameter during a contracting phase of the universe .
these equations allow the simulations presented here to proceed much closer to the singularity at the end of the collapsing universe than any previous simulations . .
And you have already written the first three sentences of the full article: typically in quintessence theories with an asymptotically vanishing effective cosmological constant , the energy contrast in dark energy @xmath3 rises from near zero for redshifts @xmath4 to near one for @xmath5 , mimicking a true cosmological constant . at late times
the quintessence field may begin to oscillate about its minimum , behaving like nonrelativistic matter , or the quintessence field may evolve toward infinity in both cases with vanishing vacuum energy . in such theories , there is a period between roughly 3.5 gyr and 20 gyr after the big bang when @xmath0 .
however if the universe continues to expand forever , or even if positive curvature begins to dominate at late times ( after the quintessence field has evolved to its minimum ) and the universe enters a contracting stage , this period when the energy densities of dark energy and matter are comparable is a small or vanishing fraction of the total lifetime of the universe ..
Please generate the next two sentences of the article | this is called the cosmic coincidence problem .
however in axion quintessence ( as in other unstable de sitter quintessence models ) , the cosmological era with @xmath6 may represent a significant fraction of the universe s lifetime if the minimum of the axion potential is negative ( unstable [ de sitter ] axion quintessence ) , thus resolving @xcite the cosmic coincidence problem . |
7,643 | Suppose that you have an abstract for a scientific paper: accuracy , descriptor size , and the time required for extraction and matching are all important factors when selecting local image descriptors . to optimize over all these requirements
, this paper presents a cuda port for the recent learned arrangement of three patches ( latch ) binary descriptors to the gpu platform .
the design of latch makes it well suited for gpu processing . owing to its small size and binary nature
, the gpu can further be used to efficiently match latch features . taken together , this leads to breakneck descriptor extraction and matching speeds .
we evaluate the trade off between these speeds and the quality of results in a feature matching intensive application . to this end
, we use our proposed cuda latch ( clatch ) to recover structure from motion ( sfm ) , comparing 3d reconstructions and speed using different representations .
our results show that clatch provides high quality 3d reconstructions at fractions of the time required by other representations , with little , if any , loss of reconstruction quality . .
And you have already written the first three sentences of the full article: _ quantity has a quality all its own _ + thomas a. callaghan jr .
local features and their descriptors play pivotal roles in many computer vision systems . as such , research on improving these methods has been immense . over the years ,
this effort yielded progressively more accurate representations ..
Please generate the next two sentences of the article | these improvements were often demonstrated on standard benchmarks designed to measure the accuracy of descriptor matching in the presence of various image transformations and other confounding factors .
it remains unclear , however , if the improved accuracy reported on these benchmarks reflects better , more useful representations when used in real world computer vision systems . |
7,644 | Suppose that you have an abstract for a scientific paper: while the properties of the signal that was discovered in the higgs searches at the lhc are consistent so far with the higgs boson of the standard model ( sm ) , it is crucial to investigate to what extent other interpretations that may correspond to very different underlying physics are compatible with the current results .
we use the next - to - minimal supersymmetric standard model ( nmssm ) as a well - motivated theoretical framework with a sufficiently rich higgs phenomenology to address this question , making use of the public tools ` higgsbounds ` and ` higgssignals ` in order to take into account comprehensive experimental information on both the observed signal and on the existing limits from higgs searches at lep , the tevatron and the lhc .
we find that besides the decoupling limit resulting in a single light state with sm - like properties , several other configurations involving states lighter or quasi - degenerate with the one at about 125 gev turn out to give a competitive fit to the higgs data and other existing constraints .
we discuss the phenomenology and possible future experimental tests of those scenarios , and compare the features of specific scenarios chosen as examples with those arising from a more global fit . .
And you have already written the first three sentences of the full article: after the discovery of a signal with a mass of about 125 gev in the higgs searches at the lhc @xcite , the prime goal is now to identify the underlying nature of the new state and to determine the mechanism of electroweak symmetry breaking . while the properties of the observed state are compatible with the ones predicted for the higgs boson of the standard model ( sm ) at the current level of precision , also a wide range of alternative interpretations could be possible , corresponding to very different underlying physics .
in particular , in models with an extended higgs sector the observed state would be accompanied by several other higgs bosons , in contrast to the minimal formulation of the sm where a single @xmath0-doublet is responsible for electroweak - symmetry breaking .
supersymmetry ( susy ) @xcite is commonly regarded as the most appealing extension of the sm , since it provides a solution for stabilising the huge hierarchy between the planck scale and the weak scale @xcite and offers further attractive features such as unification of the gauge couplings and a natural candidate for cold dark matter in the universe ..
Please generate the next two sentences of the article | a crucial prediction of supersymmetric extensions of the sm are their extended higgs sectors : the holomorphicity of the superpotential ( as well as the cancellation of gauge anomalies ) implies that at least two @xmath0 doublets with opposite hypercharge have to be present , so as to generate mass terms for both up- and down - quarks ( in a type ii 2-higgs - doublet - model fashion ) .
the minimal supersymmetric extension of the sm ( mssm ) @xcite is based on the minimal higgs sector of this kind comprising two higgs doublets , whereas the higgs sector of the next - to - minimal supersymmetric extension of the sm ( nmssm ) @xcite contains an additional ( complex ) gauge - singlet . |
7,645 | Suppose that you have an abstract for a scientific paper: this paper concerns a fast , one - step iterative technique of imaging extended perfectly conducting cracks with dirichlet boundary condition . in order to reconstruct the shape of cracks from scattered field data measured at the boundary
, we introduce a topological derivative - based electromagnetic imaging function operated at several nonzero frequencies .
the properties of the imaging function are carefully analyzed for the configurations of both symmetric and non - symmetric incident field directions .
this analysis explains why the application of incident fields with symmetric direction operated at multiple frequencies guarantees a successful reconstruction .
various numerical simulations with noise - corrupted data are conducted to assess the performance , effectiveness , robustness , and limitations of the proposed technique . perfectly conducting cracks , topological derivative , multiple frequencies , numerical experiments .
And you have already written the first three sentences of the full article: one goal of the inverse scattering problem is to find the shape of bulk or flaw in a medium using the scattered field data measured at the boundary .
this is an old but it has several of applications such as detection of cracks in material engineering , ultrasound imaging in medical sciences , and scanning anti - personnel mines hidden in the ground in military services . related researches may be found in @xcite and the references therein . in many studies , various shape reconstruction algorithms
have been developed , most of which are focused on the minimization of the least - square functional by using a newton - type iteration strategy , e.g. , level - set method @xcite ..
Please generate the next two sentences of the article | the merits of the iteration strategy is that it does not require a very large number of boundary measurements for complete shape reconstruction ; instead , in order to guarantee successful reconstruction , it demands very high computational expenditures , optimal regularization terms related to the problems at hand , calculation of a complex frchet derivative at each iteration , and _ a priori _ information of the unknown target to be reconstructed .
nevertheless , even if these conditions are satisfied , the iteration strategy must begin with an initial guess that is close to the true one in order to avoid undesirable situations such as non - convergence or falling into the local minima . |
7,646 | Suppose that you have an abstract for a scientific paper: we present a model that explains two phenomena , recently observed in high - mobility si - mos structures : ( 1 ) the strong enhancement of metallic conduction at low temperatures , @xmath0 k , and ( 2 ) the occurrence of the metal - insulator transition in 2d electron system .
both effects are prescribed to the spin - orbit interaction anomalously enhanced by the broken inversion symmetry of the confining potential well .
* introduction . * recently , in experiments with high mobility si - mos structures , a strong drop in resistivity @xmath1 has been found @xcite as temperature decreases below @xmath2 k. this effect is evidently in disagreement with the conventional interpretation of the one - parameter scaling theory ( opst ) @xcite , according to which all states in 2d system at zero magnetic field should be localized in the limit of @xmath3 .
the subsequent scaling analysis of the temperature and electric field dependencies of the conductivity @xcite has revealed a critical behavior , typical for the metal - insulator transition .
finally , convincing evidence for the existence of the extended states in 2d system at zero field has been obtained in experiments _ in magnetic field _ , in studies of the quantum hall effect to insulator transitions @xcite . the extended states which in high magnetic field are located in the centre of the corresponding landau bands , at decreasing field were found to remain in a finite energy range , giving rise to a mobility edge .
the experimental results thus suggest the existence of a true metallic state and of the metal - insulator ( m - i ) transition in 2 dimensions .
these results are in apparent contradiction with the conventional opst , and the origin of the metallic state remains puzzling . in this work , both experimental findings are explained as a consequence of the spin - orbit interaction enhanced by the broken inversion symmetry .
the suggested model provides a good agreement with the experimental data on the temperature dependence of....
And you have already written the first three sentences of the full article: author acknowledges hospitality of the institut fr halbleiter physik at the universitt linz , where the work was partly performed .
author appreciates valuable discussions with g. bauer , g. brunthaler , m.v .
entin , v. kravtsov , i.m ..
Please generate the next two sentences of the article | suslov , e.i .
rashba , and v. volkov . |
7,647 | Suppose that you have an abstract for a scientific paper: n - body simulations are a very important tool in the study of formation of large scale structures .
much of the progress in understanding the physics of galaxy formation and comparison with observations would not have been possible without n - body simulations . given the importance of this tool ,
it is essential to understand its limitations as ignoring these can easily lead to interesting but unreliable results . in this paper
we study the limitations due to the finite size of the simulation volume .
we explicitly construct the correction term arising due to a finite box size and study its generic features for clustering of matter and also on mass functions .
we show that the correction to mass function is maximum near the scale of non - linearity , as a corollary we show that the correction to the number density of haloes of a given mass changes sign at this scale ; the number of haloes at small masses is over estimated in simulations .
this over estimate results from a delay in mergers that lead to formation of more massive haloes . the same technique can be used to study corrections to other physical quantities .
the corrections are typically small if the scale of non - linearity is much smaller than the box - size
. however , there are some cases of physical interest in which the relative correction term is of order unity even though a simulation box much larger than the scale of non - linearity is used . within the context of the concordance model
, our analysis suggests that it is very difficult for present day simulations to resolve mass scales smaller than @xmath0 m@xmath1 accurately and the level of difficulty increases as we go to even smaller masses , though this constraint does not apply to multi - scale simulations .
methods : n - body simulations , numerical
gravitation
cosmology : theory , dark matter , large scale structure of the universe .
And you have already written the first three sentences of the full article: large scale structures like galaxies and clusters of galaxies are believed to have formed by gravitational amplification of small perturbations . for an overview and original references , see , e.g. , @xcite .
initial density perturbations were present at all scales that have been observed @xcite . understanding evolution of density perturbations for such initial conditions is essential for the study of formation of galaxies and large scale structures . the equations that describe the evolution of density perturbations in an expanding universe have been known for a long time and these are easy to solve when the amplitude of perturbations is small .
these equations describe the evolution of density contrast defined as @xmath2 . here.
Please generate the next two sentences of the article | @xmath3 is the density at point @xmath4 and time @xmath5 , and @xmath6 is the average density in the universe at time @xmath5 .
these are densities of non - relativistic matter , the component that clusters at all scales and is believed to drive the formation of large scale structures in the universe . |
7,648 | Suppose that you have an abstract for a scientific paper: based on the hadron transport frames , detailed simulations are carried out to discuss @xmath0 , @xmath1 productions and the significant enhancements in the very low @xmath2 region for some of the soft spectra in rhic .
elastic interactions are introduced in the simulations .
the elastic cross sections vary from different hadrons and energy scales , which can qualitatively explain the different collective motions of various hadrons . .
And you have already written the first three sentences of the full article: in the recent progress @xcite , we have developed a transport model to describe the hadron production in relativistic heavy ion collisions . in the model , a decoupling hypersurface of the fluid which consists of a group of splitting qgp droplets @xcite
is used to emit hadrons .
the model satisfies most of light hadrons spectra , but disagrees with the distributions of @xmath0 @xcite , @xmath1 @xcite and some heavy resonances @xcite . as another remarkable phenomenon.
Please generate the next two sentences of the article | , there seems to be significant enhancements at very low transverse momentum in some of the spectra for @xmath3 @xcite , @xmath4 and @xmath0 , to change the slopes . on the contrary ,
the model predicts a decrease when @xmath2 drops . |
7,649 | Suppose that you have an abstract for a scientific paper: we present an empirical method to derive photometric metallicity , reddening and distance to old stellar populations by using a few major features of the red giant branch ( rgb ) in near ir color magnitude diagrams .
we combine the observed rgb features with a set of equations linking the global metallicity [ m / h ] to suitable rgb parameters ( colors , magnitudes and slope ) , as calibrated from a homogeneous sample of galactic globular clusters with different metallicities .
this technique can be applied to efficiently derive the main population parameters of old stellar systems , in the view of using ground - based adaptive optics and space facilities to probe the stellar content of remote galaxies . .
And you have already written the first three sentences of the full article: stellar populations are fundamental tracers of the formation and evolution history of their parent galaxy .
the accurate determination of their basic parameters ( as age , metallicity and distance ) are then crucial , but this is restricted to a number of relatively nearby stellar systems , for which single stars are spatially resolved and whose magnitudes can be accurately determined . at least the brightest portion of the red giant branch ( rgb ) is needed in order to have hits on metallicity and distance , while the detection of the main sequence turn - off ( ms - to ) is required to get the age . in this respect ,
detailed investigations of simple stellar populations ( ssp , _.
Please generate the next two sentences of the article | i.e. _ coeval and chemically homogeneous stellar aggregates ) offer a unique opportunity to empirically calibrate suitable photometric indices and evolutionary features in terms of the overall metallicity of the system .
stellar clusters represent the best approximation of ssp known in the universe , hence they are ideal tools for this purpose . an empirical method to get simultaneously metallicity and reddening from the |
7,650 | Suppose that you have an abstract for a scientific paper: meson transition amplitudes of the vector , axial
vector , and tensor quark currents are analyzed within dispersion formulation of the constituent quark model .
the form factors in the decay region are given by relativistic double spectral representations through the wave functions of the inital and final mesons .
we perform heavy quark expansion of the quark model mesonic matrix elements with a next to leading order accuracy and demonstrate that matching this expansion to the heavy
quark expansion in qcd requires subtractions in the double spectral representations for the form factors and allows fixing the subtraction terms .
the isgur wise function and next to leading order universal form factors are calculated .
= -0.5 cm = 0.3 cm = 24.5 cm 22 .
And you have already written the first three sentences of the full article: theoretical description of hadronic amplitudes of the quark currents is one of the key problems of particle physics as such amplitudes provide a bridge between qcd formulated in the language of quarks and gluons and observable phenomena which deal with hadrons . in particular , the knowledge of such amplitudes
is necessary for extraction of the parameters of the quark mixing matrix in the standard model from the experiments on weak heavy hadron decays .
the difficulty in such calculations lie in the fact that hadron formation occurs at large distances where perturbative qcd methods are not applicable and nonperturbative consideration is necessary . various theoretical frameworks more or less directly related to qcd have been applied to the description of meson transition form factors : among them constituent quark models @xcite , lattice qcd simulations @xcite , qcd sum rules @xcite , analytical constraints @xcite ..
Please generate the next two sentences of the article | lattice qcd simulations is the most direct qcd based nonperturbative approach and thus should in principle provide most reliable results .
however it faces serious technical problems with placing heavy particles on the lattice and performing calculations with inclusion of quark loops . |
7,651 | Suppose that you have an abstract for a scientific paper: we study the three dimensional active scalar equation called the magneto - geostropic equation which was proposed by moffatt and loper as a model for the geodynamo processes in the earth s fluid core . when the viscosity of the fluid is positive , the constitutive law that relates the drift velocity @xmath0 and the scalar temperature @xmath1 produces two orders of smoothing .
we study the implications of this property .
for example , we prove that in the case of the non - diffusive ( @xmath2 ) active scalar equation , initial data @xmath3 implies the existence of unique , global weak solutions .
if @xmath4 with @xmath5 , then the solution @xmath6 for all time . in the case of positive diffusivity ( @xmath7 ) , even for singular initial data @xmath3 , the global solution is instantaneously @xmath8-smoothed and satisfies the drift - diffusion equation classically for all @xmath9 .
we demonstrate , via a particular example , that the viscous magneto - geostrophic equation permits exponentially growing dynamo type " instabilities . .
And you have already written the first three sentences of the full article: physicists have long realized the importance of the earth s magnetic field and that this field originates in the earth s fluid core .
the geodynamo is the process by which the rotating , convecting , electrically conducting molten iron in the earth s fluid core maintains the geomagnetic field against ohmic decay .
the convective processes in the core that produce the velocity fields required for dynamo action are a combination of thermal and compositional convection ..
Please generate the next two sentences of the article | the full dynamo problem requires the examination of the full three dimensional partial differential equations governing convective , incompressible magnetohydrodyamics ( mhd ) . in the past decades
computer models have been used to simulate the actual geodynamo . however , current computers and numerical methods require the imposition of diffusivities that are several orders of magnitude larger than those which are realistic . |
7,652 | Suppose that you have an abstract for a scientific paper: motivated by the recent neutron scattering experiment on rb@xmath0cu@xmath1snf@xmath2 [ nat .
phys .
@xmath3 , 865 ( 2010 ) ] , we investigate the effect of dzyaloshinskii - moriya interactions in a theoretical model for the magnetic structure of this material . considering the valence bond solid ground state , which has a 12-site unit cell , we develop the bond operator mean - field theory .
it is shown that the dzyaloshinskii - moriya interactions significantly modify the triplon dispersions around the @xmath4 point and cause a shift of the spin gap ( the minimum triplon gap ) position from the k to @xmath4 point in the first brillouin zone .
the spin gap is also evaluated in exact diagonalization studies on a 24-site cluster .
we discuss a magnetic transition induced by the dzyaloshinskii - moriya interactions in the bond operator framework .
moreover , the magnetization process under external magnetic fields is studied within the exact diagonalization and strong coupling expansion approaches .
we find that the results of all above approaches are consistent with the experimental findings . .
And you have already written the first three sentences of the full article: frustrated quantum magnets have been studied intensively to unveil possible novel phenomena which can be caused by the interplay of frustration and quantum effects .
spin-1/2 two dimensional ( 2d ) antiferromagnet on the kagome lattice is a central example of such frustrated quantum magnets . on the theoretical front ,
various studies have suggested several candidate ground states for the magnetically disordered phase of the spin-1/2 antiferromagnetic heisenberg model : a variety of spin liquids @xcite and valence bond solids @xcite ..
Please generate the next two sentences of the article | experimentally , a lot of effort has been made to realize the material system of such geometrically frustrated antiferromagnet .
the herbertsmithite @xcite zncu@xmath1(oh)@xmath5cl@xmath0 has the most ideal structure with uniform exchange couplings and shows no magnetic ordering down to much lower temperatures than the curie - weiss temperature . on the other hand , there may be several additional factors that would affect the nature of the ground state . |
7,653 | Suppose that you have an abstract for a scientific paper: we study fluctuations of particle absorption by a three - dimensional domain with multiple absorbing patches .
the domain is in contact with a gas of interacting diffusing particles .
this problem is motivated by living cell sensing via multiple receptors distributed over the cell surface .
employing the macroscopic fluctuation theory , we calculate the covariance matrix of the particle absorption by different patches , extending previous works which addressed fluctuations of a single current .
we find a condition when the sign of correlations between different patches is fully determined by the transport coefficients of the gas and is independent of the problem s geometry .
we show that the fluctuating particle flux field typically develops vorticity .
we establish a simple connection between the statistics of particle absorption by all the patches combined and the statistics of current in a non - equilibrium steady state in one dimension .
we also discuss connections between the absorption statistics and ( i ) statistics of electric currents in multi - terminal diffusive conductors and ( ii ) statistics of wave transmission through disordered media with multiple absorbers . .
And you have already written the first three sentences of the full article: fluctuations of currents of matter and energy is an important subject of nonequilibrium statistical mechanics .
a prototypical model problem , which attracted much attention , involves a diffusive lattice gas driven by two reservoirs of particles kept at different densities @xcite .
this simple setting has a direct relevance to experiment in at least two different contexts : statistics of electric current in mesoscopic conductors @xcite and statistics of wave transmission through disordered media @xcite ..
Please generate the next two sentences of the article | here we consider a different but closely related problem : transport of diffusing molecules into the living cell through receptors distributed on its surface @xcite .
the surrounding gas serves as a finite - density reservoir , whereas the cell receptors can be modeled as reservoirs kept at zero gas density . in their pioneering 1977 paper berg and purcell @xcite evaluated the expected steady - state current of non - interacting diffusing particles into a single receptor . |
7,654 | Suppose that you have an abstract for a scientific paper: exploiting the deep high - resolution imaging of all 5 candels fields , and accurate redshift information provided by 3d - hst , we investigate the relation between structure and stellar populations for a mass - selected sample of 6764 galaxies above @xmath0 , spanning the redshift range @xmath1 .
for the first time , we fit 2-dimensional models comprising a single fit and two - component ( i.e. , bulge + disk ) decompositions not only to the @xmath2-band light distributions , but also to the stellar mass maps reconstructed from resolved stellar population modeling .
we confirm that the increased bulge prominence among quiescent galaxies , as reported previously based on rest - optical observations , remains in place when considering the distributions of stellar mass .
moreover , we observe an increase of the typical index and bulge - to - total ratio ( with median @xmath3 reaching 40 - 50% ) among star - forming galaxies above @xmath4 . given that quenching for these most massive systems is likely to be imminent
, our findings suggest that significant bulge growth precedes a departure from the star - forming main sequence .
we demonstrate that the bulge mass ( and ideally knowledge of the bulge and total mass ) is a more reliable predictor of the star - forming versus quiescent state of a galaxy than the total stellar mass .
the same trends are predicted by the state - of - the - art semi - analytic model by somerville et al . in the latter , bulges and black holes
grow hand in hand through merging and/or disk instabilities , and agn - feedback shuts off star formation .
further observations will be required to pin down star formation quenching mechanisms , but our results imply they must be internal to the galaxies and closely associated with bulge growth . .
And you have already written the first three sentences of the full article: the mechanisms driving the shutdown of star - forming galaxies ( sfgs ) , quenching , remains one of the least understood puzzles in galaxy formation to date . in the low - redshift universe ,
galaxies show a bimodal color distribution , accompanied by a bimodality of morphologies ( see * ? ? ?
* ; * ? ? ?.
Please generate the next two sentences of the article | spiral galaxies have low bulge - to - disk ratios and are commonly the site of active star formation leading to blue colors .
passive galaxies are observed to be mostly spheroid - dominated . |
7,655 | Suppose that you have an abstract for a scientific paper: in this paper , the radiation field is defined for solutions to einstein vacuum equations which are close to minkowski space - time with spacial dimension @xmath0 .
the regularity properties and asymptotic behavior of those einstein vacuum solutions are established at the same time . in particular , the map from cauchy intial data to the radiation field is proved to be an isomorphism when restricting to a small neighborhood of minkowski data in suitable weighted b - sobolev spaces . .
And you have already written the first three sentences of the full article: the einstein vacuum equations determine a manifold @xmath1 with a lorentzian metric with vanishing ricci curvature : @xmath2 the set @xmath3 : standard minkowski metric @xmath4 on @xmath5 describes the minkowski space - time solution of the system ( [ eq.1 ] ) , which is stable under small perturbation according to the remarkable work @xcite of d. christodoulou and s. klainerman in 1993 . in this paper
, the authors showed that for @xmath6 given @xmath7-dimensional manifold @xmath8 with a riemannian metric @xmath9 and a symmetric two tensor @xmath10 , such that @xmath11 is close to the euclidean space , @xmath10 is close to @xmath12 and @xmath13 satisfy the constraint equations : @xmath14_j^i[k_0]_i^j+[k_0]_i^i[k_0]_j^j=0,\quad \nabla^j[k_0]_{ij}-\nabla_i[k_0]_j^j=0\ ] ] where @xmath15 is the scalar curvature of @xmath9 and @xmath16 is the covariant differentiation w.r.t .
@xmath9 , then we can find out a @xmath17-dimensional lorentzian manifold @xmath18 satisfying ( [ eq.1 ] ) and an embedding @xmath19 such that @xmath9 is the restriction of @xmath20 to @xmath8 and @xmath10 is the second fundamental form ..
Please generate the next two sentences of the article | the einstein vacuum equations are invariant under diffeomorphism . in the work of y. choquet - bruhat , @xcite followed by @xcite ,
this allows her to choose a special _ harmonic gauge _ to prove the existence and uniqueness up to diffeomorphism of a maximal globally hyperbolic smooth space - time arising from any set of smooth initial data . |
7,656 | Suppose that you have an abstract for a scientific paper: heterogeneity in biological molecules , resulting in molecule - to - molecule variations in their dynamics and function , is an emerging theme . to elucidate the consequences of heterogeneous behavior at the single molecule level
, we propose an exactly solvable model in which the unfolding rate due to mechanical force depends parametrically on an auxiliary variable representing an entropy barrier arising from fluctuations in internal dynamics . when the rate of fluctuations @xmath0 a measure of dynamical disorder @xmath0 is comparable to or smaller than the rate of force - induced unbinding , we show that there are two experimentally observable consequences : non - exponential survival probability at constant force , and a heavy - tailed rupture force distribution at constant loading rate . by fitting our analytical expressions to data from single molecule pulling experiments on proteins and dna ,
we quantify the extent of disorder .
we show that only by analyzing data over a wide range of forces and loading rates can the role of disorder due to internal dynamics be quantitatively assessed .
complex systems , characterized by processes that occur over a wide spectrum of time and length scales , often exhibit heterogeneous behavior .
spin glasses with quenched randomness @xcite and structural glasses in which randomness is self - generated @xcite are two classic examples where heterogeneity is indicated by the violation of the law of large numbers @xcite .
these systems exhibit sub - sample to sub - sample variations in measurable quantities . for biological systems
, it is increasingly becoming appreciated that there are cell - to - cell variations ( on length scales @xmath1 @xmath2 m ) @xcite as well as molecule - to - molecule variations ( @xmath1 nm scales ) .
manifestation of heterogeneous behavior on the @xmath2 m length scale is easier to fathom than on the molecular scale . in a pioneering study , evidence for disorder in enzymes
was presented using single molecule....
And you have already written the first three sentences of the full article: * derivation of the smoluchowski equation for fb model :* according to the liouville theorem ( @xmath143 ) the time evolution of probability density @xmath144 in terms of @xmath14 and @xmath13 satisfies @xmath145 insertion of two langevin equations ( eq.(1 ) in the main text ) for the fluctuating bottleneck model @xmath146 $ ] and @xmath147 into eq.[eqn : liouville ] leads to where @xmath149 and @xmath150 . using the vector notation as in the second line of eq.[eqn : liouville2 ] , one can formally solve for the probability density @xmath151 as @xmath152 averaging @xmath151 over noise after iterating @xmath151 into the noise related term in the integrand and exploiting the fluctuation - dissipation theorem , we obtain the smoluchowski equation for @xmath144 in the presence of a reaction sink , @xmath153 , @xmath154\overline{\varphi}(x , r , t ) , \label{eqn : smol}\ ] ] where @xmath155 and @xmath156 . integrating both sides of the equation over @xmath14 by defining @xmath157 leads to @xmath158 . by setting @xmath159 where @xmath160
, we get @xmath161\overline{c}(r , t ) , \label{eqn : step2}\ ] ] where @xmath162 with @xmath163 . in all likelihood , @xmath164 represents the product of diffusion coefficient @xmath165 associated with barrier crossing dynamics and the contribution of dynamics at the barrier top .
thus , under tension @xmath10 , one can set @xmath166 where @xmath167 and @xmath168 describes the correction due to geometrical information of the cross section of bottleneck @xcite ..
Please generate the next two sentences of the article | therefore , under tension @xmath10 , eq.[eqn : step2 ] becomes eq.(2 ) in the main text .
+ * solution of the smoluchowski equation with time - dependent sink :* for the problem with a constant loading rate , the sink function of our smoluchowski equation becomes time - dependent , resulting in the following equation for the flux @xmath39 , with @xmath170 . |
7,657 | Suppose that you have an abstract for a scientific paper: the euv imaging spectrometer ( eis ) on the hinode satellite is capable of measuring emission line center positions for gaussian line profiles to a fraction of a spectral pixel , resulting in relative solar doppler - shift measurements with an accuracy of less than a km s@xmath0 for strong lines .
we show an example of the application of that capability to an active region sit - and - stare observation in which the eis slit is placed at one location on the sun and many exposures are taken while the spacecraft tracking keeps the same solar location within the slit . for the active region
examined ( noaa 10930 ) , we find that significant intensity and doppler - shift fluctuations as a function of time are present at a number of locations .
these fluctuations appear to be similar to those observed in high - temperature emission lines with other space - borne spectroscopic instruments . with its increased sensitivity over earlier spectrometers and its ability to image many emission lines simultaneously
, eis should provide significant new constraints on doppler - shift oscillations in the corona . .
And you have already written the first three sentences of the full article: the euv imaging spectrometer ( eis ) on hinode uses multilayer optics to produce stigmatic spectra in two 40 wide euv bands centered at 195 and 270 .
emission lines present in these bands originate in the solar transition region and corona , permitting detailed study of the temperature , density , and dynamical structure of these regions .
the hinode mission is described in @xcite ..
Please generate the next two sentences of the article | an overall description of eis is available in @xcite .
@xcite provides more detailed information on the eis calibration , and @xcite provides details of the optics and mechanisms . |
7,658 | Suppose that you have an abstract for a scientific paper: accurate @xmath0 transition energies in molecular hydrogen were determined for transitions originating from levels with highly - excited vibrational quantum number , @xmath1 , in the ground electronic state .
doppler - free two - photon spectroscopy was applied on vibrationally excited h@xmath2 , produced via the photodissociation of h@xmath3s , yielding transition frequencies with accuracies of @xmath4 mhz or @xmath5 @xmath6 .
an important improvement is the enhanced detection efficiency by resonant excitation to autoionizing @xmath7 electronic rydberg states , resulting in narrow transitions due to reduced ac - stark effects . using known @xmath8 level energies , the level energies of @xmath9 states
are derived with accuracies of typically 0.002 @xmath6 .
these experimental values are in excellent agreement with , and are more accurate than the results obtained from the most advanced _ ab initio _ molecular theory calculations including relativistic and qed contributions . .
And you have already written the first three sentences of the full article: the advance of precision laser spectroscopy of atomic and molecular systems has , over the past decades , been closely connected to the development of experimental techniques such as tunable laser technology @xcite , saturation spectroscopy @xcite , two - photon doppler - free spectroscopy @xcite , cavity - locking techniques @xcite , and ultimately , the invention of the frequency comb laser @xcite , developments to which prof .
theodore hnsch has greatly contributed .
these inventions are being exploited to further investigate at ever - increasing precision the benchmark atomic system the hydrogen atom , evinced by the advance in spectroscopic accuracy of atomic hydrogen measurements by more than seven orders of magnitude since the invention of the laser @xcite ..
Please generate the next two sentences of the article | the spectroscopy of the 1s-2s transition in atomic hydrogen , at @xmath10 relative accuracy @xcite , provides a stringent test of fundamental physical theories , in particular quantum electrodynamics ( qed ) .
currently , the theoretical comparison to precision measurements on atomic hydrogen are limited by uncertainties in the proton charge radius @xmath11 . |
7,659 | Suppose that you have an abstract for a scientific paper: the large - alphabet quantum cryptography protocol based on the two - mode coherently correlated multi - photon beams is proposed . the alphabet extension for the protocol
is shown to result in the increase of the qkd effectiveness and security .
pacs numbers : 03.67.-a,03.67.dd,03.67.hk .
And you have already written the first three sentences of the full article: quantum cryptography @xcite , being the first practical realization of quantum physics at the single quanta level , is the art of creating data channels physically secure against eavesdropping .
most of its successful practical realizations are based on the use of single photon information coding though optical fiber links thus being based on a weak laser pulses .
the security of the protocols is based on the state perturbation during the eavesdropping @xcite or the measurement correlations analysis with the bell inequalities check @xcite . since.
Please generate the next two sentences of the article | key bits are encoded in the single photon states the appearance of the additional photons may seriously undermine the protocol security by leading to the successful listening - in because additional photons states can be imperceptibly measured by an eavesdropper . thus the security reasons require the minimizing of the multi - photon pulses appearance probability making most of the pulses empty , which limits the key rate and results in an additional error rate caused by the single - photon counting detectors , which are inclined to `` dark counts '' , clicking when the photon is missing @xcite .
this leads to some contradiction between the effectiveness and security of the existing quantum key distribution ( qkd ) schemes . |
7,660 | Suppose that you have an abstract for a scientific paper: following an approach initially outlined by mckee & holliman @xcite , we investigate the structure and stability of dense , starless molecular cloud cores . we model those as spherical clouds in hydrostatic equilibrium and supported against gravity by thermal , turbulent , and magnetic pressure .
we determine the gas pressure by solving for thermal equilibrium between heating and cooling , while the turbulent and magnetic pressures are assumed to obey polytropic equations of state . in comparing the models to observed cloud cores we find that the observed
peak column densities often exceed the limit for stable equilibria supported by thermal pressure alone , suggesting significant non - thermal pressure if the cores are to be stable .
non - thermal support is also needed to stabilize cores embedded in molecular clouds with high average pressures . since the observed molecular linewidths of cores suggest that the turbulent pressure is lower than the thermal pressure , magnetic field are likely a dominant pressure component in many such cores . .
And you have already written the first three sentences of the full article: to model a gas cloud in hydrostatic equilibrium we make the simplified assumption that the gas pressure consists of the sum of thermal ( subscript `` th '' ) , turbulent wave ( `` w '' ) , and magnetic ( `` m '' ) pressure components , @xmath0 we compute the thermal pressure through a detailed thermal equilibrium calculation , but the wave and magnetic pressures are assumed to obey a polytropic equation of state , @xmath1 i.e. the pressure only depends on density , and @xmath2 , the polytropic exponent , is constant in a given object . given the thermal and non - thermal gas pressure , it is possible to construct hydrostatic equilibria for any surface pressure and central to surface density contrast .
we assume spherical symmetry for simplicity . whether a given hydrostatic equilibrium model cloud is gravitationally stable depends on its response to perturbations in pressure or density .
different equations of state apply for such perturbations ..
Please generate the next two sentences of the article | for example , if the perturbation occurred on a time scale shorter than the cooling time , the scaling of the thermal pressure with density would be stiffer than if the perturbation would be allowed to reach thermal equilibrium . to analyze the stability we make the simple assumption that the perturbation obeys a polytropic equation of state , but with some different `` adiabatic index '' , @xmath3 : @xmath4 where @xmath5 are infinitesimal perturbations , and the subscript `` 0 '' refers to values before the perturbation .
a hydrostatic equilibrium cloud is stable against spontaneous contraction or expansion when at any point in the cloud , the pressure increases during a compression or decreases during an expansion , i.e. , @xmath6 where @xmath7 is the radius from the cloud center . |
7,661 | Suppose that you have an abstract for a scientific paper: it is well - known that the dominant mechanism to produce hadronic bound states with large transverse momentum is fragmentation .
this mechanism is described by the fragmentation functions ( ffs ) which are the universal and process - independent functions . here
, we review the perturbative ffs formalism as an appropriate tool for studying these hadronization processes and detail the extension of this formalism at next - to - leading order ( nlo ) . using the suzuki s model
, we calculate the perturbative qcd ff for a heavy quark to fragment into a s - wave heavy meson at nlo . as an example
, we study the lo and nlo ffs for a charm quark to split into the s - wave @xmath0-meson and compare our analytic results both with experimental data and well - known phenomenological models . .
And you have already written the first three sentences of the full article: heavy quark production processes provide a powerful insight into our understanding of quantum chromodynamics ( qcd ) . the study of heavy mesons properties is also a subject of interest for understanding of quark - gluon interaction dynamics .
generally , two mechanisms are investigated for the production of heavy mesons : recombination and fragmentation @xcite . in the first scheme ,
heavy mesons are formed from heavy - heavy or heavy - light quarks which are produced independently in hard subprocesses . in the second mechanism.
Please generate the next two sentences of the article | , the fragmentation refers to the process of a parton which carries large transverse momentum and subsequently forms a jet containing the expected hadron @xcite . at sufficiently large transverse momentum of the heavy meson production , the direct leading - order production scheme ( recombination mechanism )
is normally suppressed while the fragmentation scheme becomes dominant , though it is formally of higher order in the strong coupling constant @xmath1 @xcite . |
7,662 | Suppose that you have an abstract for a scientific paper: we calculate the average single particle density of states in graphene with disorder due to impurity potentials . for unscreened short - ranged impurities ,
we use the non - self - consistent and self - consistent born and @xmath0-matrix approximations to obtain the self - energy . among these
, only the self - consistent @xmath0-matrix approximation gives a non - zero density of states at the dirac point .
the density of states at the dirac point is non - analytic in the impurity potential . for screened short - ranged and charged long - range impurity potentials ,
the density of states near the dirac point typically increases in the presence of impurities , compared to that of the pure system . .
And you have already written the first three sentences of the full article: the recent experimental realization of a single layer of carbon atoms arranged in a honey - comb lattice has prompted much excitement and activity in both the experimental and theoretical physics communities @xcite .
carriers in graphene ( both electrons and holes ) have a linear bare kinetic energy dispersion spectra around the @xmath1 and @xmath2 points ( the dirac points " ) of the brillouin zone . the ability of experimentalists to tune the chemical potential to lie above or below the dirac point energy ( by application of voltages to gates in close proximity to the graphene sheets ) allows the carriers to be changed from electrons to holes in the same sample .
this sets graphene apart from other two dimensional ( 2d ) carrier systems that have a parabolic dispersion relation , and typically have only one set of carriers , i.e. either electrons or holes ..
Please generate the next two sentences of the article | another unique electronic property , the absence of back - scattering , has led to the speculation that carrier mobilities of 2d graphene monolayers ( certainly at room temperature , but also at low temperature ) could be made to be much higher than any other field - effect type device , suggesting great potential both for graphene to be the successor to si - mosfet ( metal - oxide - semicondcutor field effect transistor ) devices and for the discovery of new phenomena that normally accompanies any significant increase in carrier mobility @xcite .
it is therefore of considerable fundamental and technological interest to understand the electronic properties of graphene @xcite . |
7,663 | Suppose that you have an abstract for a scientific paper: this paper concerns optical properties of the isotropic phase above the isotropic - cholesteric transition and of the blue phase bp iii .
we introduce an effective index , which describes spatial dispersion effects such as optical rotation , circular dichroism , and the modification of the average index due to the fluctuations .
we derive the wavelength dependance of these spatial dispersion effects quite generally without relying on an expansion in powers of the chirality and without assuming that the pitch of the cholesteric @xmath0 is much shorter than the wavelength of the light @xmath1 , an approximation which has been made in previous studies of this problem .
the theoretical predictions are supported by comparing them with experimental spectra of the optical activity in the bp iii phase . .
And you have already written the first three sentences of the full article: chirality in liquid crystals produces a fascinating variety of phases , such as the blue phases .
three blue phases ( bps ) designated bp i , bp ii , and bp iii have been identified , and their structures are now well understood .
bp i and bp ii exhibit long - range periodic order at the half micron scale and bragg scatter visible light . for these reasons ,.
Please generate the next two sentences of the article | the optical study of blue phases is an active field of research , with a particular emphasis on spatial dispersion effects such as the optical activity . the first experiments on the optical activity in the pretransitional region of the isotropic phase above the isotropic - cholesteric transition were carried out by cheng and meyer @xcite .
using a general formulation due to de gennes , they calculated and confirmed experimentally that the pretransitional optical activity depends on the temperature as @xmath2 , where @xmath3 is the metastability temperature of the isotropic phase . |
7,664 | Suppose that you have an abstract for a scientific paper: the cross sections of the processes @xmath0 , @xmath1 and @xmath2 were measured in the snd experiment at the vepp-2 m collider in the energy region near the @xmath3 meson .
these measurements were based on about @xmath4 @xmath5 , @xmath6 @xmath7 and @xmath8 @xmath9 selected events .
the measured cross sections have been analyzed in the framework of the vector meson dominance model and the main parameters of the @xmath10-resonance were obtained , such as its mass , width , the production cross section and branching ratios of the main decay modes .
the measured value of the @xmath10 meson total width , @xmath11 is lower than the present world average of @xmath12 mev .
contributions in addition to the conventional vector meson dominance model were found in the @xmath2 reaction cross section . .
And you have already written the first three sentences of the full article: cross sections of the reactions @xmath13 and @xmath2 , are determined by strong and electromagnetic interactions of the light quarks @xmath14 and can not be evaluated at present from first principles . but a rather good description of these cross sections is provided by the vector meson dominance model ( vdm ) with phenomenologically adjusted coupling constants ( @xmath15 , @xmath16 , @xmath17 , @xmath18 ) . in the vdm ,
the cross sections are determined by the amplitudes of vector meson v transitions ( @xmath19 , @xmath20 , @xmath21 ) into the final state : @xmath22 , @xmath23 . in the energy range from 980 to 1070 mev ,
the main contributions to the @xmath13 and @xmath2 cross sections come from the @xmath10-meson . therefore the measurement of these cross sections allows us to determine the @xmath10-resonance main parameters and study its interference with other vector mesons ..
Please generate the next two sentences of the article | such studies provide important information about light meson physics .
earlier these processes were studied in several experiments : @xmath24 @xcite , @xmath1 @xcite and @xmath0 @xcite . |
7,665 | Suppose that you have an abstract for a scientific paper: for the symbiotic branching model introduced in @xcite , it is shown that aging and intermittency exhibit different behaviour for negative , zero , and positive correlations .
our approach also provides an alternative , elementary proof and refinements of classical results concerning second moments of the parabolic anderson model with brownian potential . some refinements to more general ( also infinite range ) kernels of recent aging results of @xcite for interacting diffusions are given . , .
And you have already written the first three sentences of the full article: for the last three decades , equations of the type @xmath0 have been studied intensively . here ,
@xmath1 , @xmath2 , @xmath3 , @xmath4 are transition rates on @xmath5 , and @xmath6 is a familiy of independent brownian motions .
the following special cases with very different interpretations and different behaviour are quite common in the literature ..
Please generate the next two sentences of the article | [ ex1 ] the ( wright - fisher ) stepping stone model from mathematical genetics : @xmath7 .
[ ex2 ] the parabolic anderson model ( with brownian potential ) from mathematical physics : @xmath8 . |
7,666 | Suppose that you have an abstract for a scientific paper: porous silicon ( p - si ) , prepared by two routes ( metal induced etching ( mie ) and laser induced etching ( lie ) ) have been studied by comparing the surface morphologies .
a uniformly distributed smaller ( submicron sized ) pores are formed when mie technique is used because the pore formation is driven by uniformly distributed metal ( silver in present case ) nanoparticles , deposited prior to the porosification step . whereas in p - si samples prepared by lie technique , wider pores with some variation in pore size as compared to mie technique
is observed because a laser having gaussian profile of intensity is used for porosification .
uniformly distribute well - aligned si nanowires are observed in samples prepared by mie method as seen using cross - sectional sem imaging , which shows a single photoluminescence ( pl ) peak at 1.96 ev corresponding to red emission at room temperature .
the single pl peak confirms the presence of uniform sized nanowires in mie samples .
these vertically aligned si nanowires can be used for field emission application . .
And you have already written the first three sentences of the full article: attention received by porous silicon ( p - si ) from scientists is known from more than couple of decades since the discovery of its light emission properties [ 1,2 ] .
p - si is still being studied due to its applications in various fields in addition to optoelectronic devices [ 1 - 7 ] .
many reports shows applications of p - si in advanced sensing[8 - 11 ] , in making electrodes for batteries [ 12,13 ] , in carrying out mass spectroscopy [ 14 ] in carrying out mass spectroscopy [ 15 ] and in field effect transistors [ 16 , 17 ] ..
Please generate the next two sentences of the article | different methods to fabricate p - si & it s various applications / properties have been studied in depth and very good reports are available [ 18 , 19 ] .
various techniques used for the formation of p - si include strain etching [ 20 , 21 ] of si wafer in a solution of hno @xmath0 & hf acid , electrochemical etching [ 22 , 23 ] where an electrical bias is used for porosification of si wafer in etching solution of hf acid . a simpler method of photochemical etching also known as laser induced etching ( lie ) was used by choy and cheah [ 24 ] and later used by many others [ 25 - 29 ] . |
7,667 | Suppose that you have an abstract for a scientific paper: the ability to control the crystallization behaviour ( including its absence ) of particles , be they biomolecules such as globular proteins , inorganic colloids , nanoparticles , or metal atoms in an alloy , is of both fundamental and technological importance .
much can be learnt from the exquisite control that biological systems exert over the behaviour of proteins , where protein crystallization and aggregation are generally suppressed , but where in particular instances complex crystalline assemblies can be formed that have a functional purpose .
we also explore the insights that can be obtained from computational modelling , focussing on the subtle interplay between the interparticle interactions , the preferred local order and the resulting crystallization kinetics .
in particular , we highlight the role played by `` frustration '' , where there is an incompatibility between the preferred local order and the global crystalline order , using examples from atomic glass formers and model anisotropic particles . .
And you have already written the first three sentences of the full article: controlling crystallization is a subject of considerable importance both from a fundamental and an applied perspective .
chemical physicists want to understand how the interparticle interactions determine the most favoured crystal structure and the ease with which crystallization can occur .
biochemists want to know the best recipe to crystallize the protein in which they are interested , so that they can then determine its structure ..
Please generate the next two sentences of the article | nanotechnologists want to know how to get colloids or nanoparticles to self - assemble into a given target structure , such as a diamond lattice because of its potential importance in photonics .
metallurgists want to be able to predict which alloys will most readily avoid crystallization , and instead form a metallic glass.@xcite in this paper we want to take a theoretical and computer simulation perspective on the factors that control crystallization , and its absence , in these kinds of systems . |
7,668 | Suppose that you have an abstract for a scientific paper: we investigate the critical behavior of three - dimensional antiferromagnetic cp@xmath0 ( acp@xmath0 ) models in cubic lattices , which are characterized by a global u(@xmath1 ) symmetry and a local u(1 ) gauge symmetry . assuming that critical fluctuations are associated with a staggered gauge - invariant ( hermitian traceless matrix ) order parameter , we determine the corresponding landau - ginzburg - wilson ( lgw ) model . for @xmath2
this mapping allows us to conclude that the three - component acp@xmath3 model undergoes a continuous transition that belongs to the o(8 ) vector universality class , with an effective enlargement of the symmetry at the critical point .
this prediction is confirmed by a detailed numerical comparison of finite - size data for the acp@xmath3 and the o(8 ) vector models .
we also present a renormalization - group ( rg ) analysis of the lgw theories for @xmath4 .
we compute perturbative series in two different renormalization schemes and analyze the corresponding rg flow . we do not find stable fixed points that can be associated with continuous transitions . .
And you have already written the first three sentences of the full article: cp@xmath0 models are a class of models in which the fundamental field is a complex @xmath1-component unit vector ( more precisely , an element of the complex projective manifold cp@xmath0 ) , and which are characterized by a global u(@xmath1 ) symmetry and a local u(1 ) gauge symmetry .
they emerge as effective theories of su(@xmath1 ) quantum antiferromagnets @xcite and of scalar electrodynamics with a compact u(1 ) gauge group .
the simplest three - dimensional ( 3d ) cp@xmath0 lattice model is defined by the hamiltonian @xmath5 where the sum is over the nearest - neighbor sites of a cubic lattice , @xmath6 are @xmath1-component complex vectors satisfying @xmath7 ..
Please generate the next two sentences of the article | the model is ferromagnetic for @xmath8 , antiferromagnetic for @xmath9 .
the cp@xmath10 model can be mapped onto the o(3)-symmetric heisenberg model . |
7,669 | Suppose that you have an abstract for a scientific paper: any object on earth has two fundamental properties : it is finite , and it is made of atoms . structural information about an object can be obtained from diffraction amplitude measurements that account for either one of these traits .
nyquist - sampling of the fourier amplitudes is sufficient to image single particles of finite size at any resolution .
atomic resolution data is routinely used to image molecules replicated in a crystal structure . here
we report an algorithm that requires neither information , but uses the fact that an image of a natural object is compressible .
intended applications include tomographic diffractive imaging , crystallography , powder diffraction , small angle x - ray scattering and random fourier amplitude measurements . .
And you have already written the first three sentences of the full article: in a standard imaging system , light scattered from an object forms a diffraction pattern which encodes information about the object fourier components .
a lens recombines the scattered rays so that they interfere correctly to form an ) . ,
title="fig:",scaledwidth=20.0% ] , title="fig:",scaledwidth=20.0% ] these ideas , along with the development of powerful light sources , producing collimated beams of coherent x - rays , enabled the development of coherent x - ray diffraction microscopy @xcite ( aka lensless or diffractive imaging ) ..
Please generate the next two sentences of the article | this technique aims at imaging , through coherent illumination , fourier amplitude measurements and adequate sampling , macroscopic objects such as entire cellular organisms @xcite , or nanoporous aerogel structures @xcite .
see @xcite for a review . |
7,670 | Suppose that you have an abstract for a scientific paper: we study the stability properties of isolated star forming dwarf galaxies which undergo dynamically driven star bursts induced by stellar feedback . here
we focus on the impact of the adopted ism model , i.e. either a diffuse or a clumpy ism .
we apply a one - zone model extended for active dynamical evolution .
this allows for a coupling between the dynamical state of the galaxy and its internal properties like star formation activity or the thermal state ( or dynamical pressure , respectively ) of the interstellar medium ( ism ) .
we found two major types of repetitive star bursts : one set ( type a ) of quasi - periodic star bursts is related to the dynamical timescale of the galaxy . in that case , the star formation follows the variations of the gas density induced by decaying virial oscillations .
the second set ( type b ) of recurrent star bursts is characterized by a long quiescence period given by the sum of the dynamical and the dissiptional timescale : after a first burst , the inserted energy leads to a substantial expansion of the system , by this stopping any significant sf activity .
a next burst might occur , when the gas reaches high densities again , i.e. after the gas recollapsed and the energy injected by stellar feedback is dissipated . in case of a diffuse ism model , type a bursts are the most common type due to the high efficiency of radiative cooling ( no type b bursts are found ) .
bursts occur then mainly during an initial transitory phase . in case of a clumpy ism model ( i.e. dissipation by inelastic cloud - cloud collisions ) ,
the dissipative timescale is of the order of the dynamical time or longer .
this allows for both , type a and type b bursts . whereas initial transitory bursts are quite common , type b bursts are only found in a small mass range for given feedback and dissipation parameters . .
And you have already written the first three sentences of the full article: starbursts are a well known phenomenon in some dirrs ( e.g. gallagher & hunter @xcite ; for a critical discussion of the exact definition of starbursts see knapen & james @xcite ) .
they imply a mechanism to organise large - scale star formation which can not operate all the time due to fast gas consumption . moreover
, the instability leading to an episodic sfr should work in a small parameter range only , because most of the isolated dirrs seem to evolve in a highly self - regulated manner ..
Please generate the next two sentences of the article | the first theoretical models dealing with the variability of the star formation rate in galaxies were based on closed - box models . for reasonable models of the interstellar medium ( ism ) it turned out that stellar feedback is rather efficient in suppressing instabilities ( e.g. ikeuchi & tomita @xcite , scalo & struck - marcell @xcite ) .
these models only allow for a burst - like behaviour when a long time - delay between star formation and stellar feedback is introduced . |
7,671 | Suppose that you have an abstract for a scientific paper: we prove that borel qcd sum rules for heavy
light currents yield very strong correlations between the @xmath0-quark mass @xmath1 and the @xmath2-meson decay constant @xmath3 namely , @xmath4 this fact opens the possibility of an accurate sum - rule extraction of @xmath1 by using @xmath5 as input . combining precise lattice qcd determinations of @xmath5 with our sum - rule analysis based on the three - loop @xmath6 heavy
light correlation function leads to @xmath7 .
And you have already written the first three sentences of the full article: the @xmath0-quark mass for instance , the @xmath8 running mass at renormalization scale @xmath9 @xmath10 or @xmath11 is one of the fundamental parameters of the standard model and therefore its precise knowledge is highly desirable .
the latest edition of the review of particle physics reports @xmath12 @xcite .
a direct way to determine @xmath1 is by means of lattice qcd simulations ; however , since the physical @xmath0-quark is too heavy for current lattice setups , the determination of @xmath1 from pure lattice qcd requires either the extrapolation of the lattice results from lighter simulated masses or the use of the heavy - quark effective theory ( hqet ) formulated on the lattice . using the former approach ,.
Please generate the next two sentences of the article | the values @xmath13 @xcite and @xmath14 @xcite have recently been deduced , while the results @xmath15 @xcite , @xmath16 @xcite , and @xmath17 @xcite have been determined adopting the hqet - based approach .
all above findings have been obtained using unquenched gauge configurations with @xmath18 dynamical flavors in the sea . |
7,672 | Suppose that you have an abstract for a scientific paper: it has been recently realized that dissipative processes can be harnessed and exploited to the end of coherent quantum control and information processing . in this spirit
we consider strongly dissipative quantum systems admitting a non - trivial manifold of steady states .
we show how one can enact adiabatic coherent unitary manipulations e.g. , quantum logical gates , inside this manifold by adding a weak , time - rescaled , hamiltonian term into the system s liouvillian .
the effective long - time dynamics is governed by a projected hamiltonian which results from the interplay between the weak unitary control and the fast relaxation process .
the leakage outside the manifold entailed by the hamiltonian term is suppressed by an environment - induced symmetrization of the dynamics .
we present applications to quantum - computation in decoherence - free subspaces and noiseless subsystems and numerical analysis of non - adiabatic errors . _
introduction: _ weak coupling to the environmental degrees of freedom is often regarded as one of the essential prerequisites for realizing quantum information processing .
in fact decoherence and dissipation generally spoil the unitary character of the quantum dynamics and induce errors into the computational process . in order to overcome such an obstacle a variety of techniques
have been devised including quantum error correction @xcite , decoherence - free subspaces ( dfss ) @xcite and noiseless subsystems ( nss ) @xcite .
however , it has been recently realized that dissipation and decoherence may even play a positive role to the aim of coherent quantum manipulations .
indeed , it has been shown that , properly engineered , dissipative dynamics can in principle be tailored to enact quantum information primitives such as quantum state preparation @xcite , quantum simulation @xcite and computation @xcite . in this letter
we investigate the regime where the coupling of the system to the environment is very strong and the open system dynamics....
And you have already written the first three sentences of the full article: in this section we provide a proof of eq .
( 2 ) of the main text .
our approach and terminology rely heavily on the classical text @xcite ..
Please generate the next two sentences of the article | let @xmath207 . for @xmath208 , @xmath2
is assumed to have a degenerate steady state manifold , i.e. @xmath209 for small non - zero @xmath210 , some eigenvalues of @xmath211 ( may ) depart from @xmath212 . |
7,673 | Suppose that you have an abstract for a scientific paper: surface wave patterns are investigated experimentally in a system geometry that has become a paradigm of quantum chaos : the stadium billiard .
linear waves in bounded geometries for which classical ray trajectories are chaotic are known to give rise to scarred patterns . here , we utilize parametrically forced surface waves ( faraday waves ) , which become progressively nonlinear beyond the wave instability threshold , to investigate the subtle interplay between boundaries and nonlinearity .
only a subset ( three main types ) of the computed linear modes of the stadium are observed in a systematic scan .
these correspond to modes in which the wave amplitudes are strongly enhanced along paths corresponding to certain periodic ray orbits .
many other modes are found to be suppressed , in general agreement with a prediction by agam and altshuler based on boundary dissipation and the lyapunov exponent of the associated orbit .
spatially asymmetric or disordered ( but time - independent ) patterns are also found even near onset . as the driving acceleration is increased ,
the time - independent scarred patterns persist , but in some cases transitions between modes are noted .
the onset of spatiotemporal chaos at higher forcing amplitude often involves a nonperiodic oscillation between spatially ordered and disordered states .
we characterize this phenomenon using the concept of pattern entropy .
the rate of change of the patterns is found to be reduced as the state passes temporarily near the ordered configurations of lower entropy .
we also report complex but highly symmetric ( time - independent ) patterns far above onset in the regime that is normally chaotic . .
And you have already written the first three sentences of the full article: parametrically forced surface waves arising as a result of the faraday instability have provided an excellent opportunity to study nonlinear pattern formation .
one of the special features of this system is that the system size relative to the basic correlation length can be varied so that both the large aspect ratio and small aspect ratio limits can be explored . at large aspect ratio ,
all of the classic ordered patterns have been found , including stripes , hexagons , and squares ; additional exotic structures such as quasicrystalline and superlattice patterns have also been found , as well as secondary instabilities giving rise to spatiotemporal chaos ..
Please generate the next two sentences of the article | extensive references can be found in @xcite .
the case of small aspect ratio has also been studied in rectangular and circular containers . |
7,674 | Suppose that you have an abstract for a scientific paper: recently we proposed a particle - number - conserving theory for nuclear pairing [ jia , phys .
rev .
c * 88 * , 044303 ( 2013 ) ] through the generalized density matrix formalism .
the relevant equations were solved for the case when each single - particle level has a distinct set of quantum numbers and could only pair with its time - reversed partner ( bcs - type hamiltonian ) . in this work we consider the more general situation when several single - particle levels could have the same set of quantum numbers and pairing among these levels
is allowed ( hfb - type hamiltonian ) .
the pair condensate wavefunction ( the hfb wavefunction projected onto good particle number ) is determined by the equations of motion for density matrix operators instead of the variation principle .
the theory is tested in the simple two - level model with factorizable pairing interactions and the semi - realistic model with the zero - range delta interaction . .
And you have already written the first three sentences of the full article: the bardeen - cooper - schrieffer ( bcs ) theory @xcite or its advanced version the hartree - fock - bogoliubov ( hfb ) theory @xcite has long been used to treat pairing correlations @xcite in atomic nuclei . in the mean field
we introduce the bogoliubov quasi - particles and write the ground state as a slater determinant of the latter .
usually the variation principle is used to determine the structure of the quasi - particles . although enjoying great success , the method has disadvantages of breaking the exact particle number and a need for an unphysical minimum pairing - force strength @xcite.
Please generate the next two sentences of the article | . the theory could be improved by the `` variation after particle - number projection '' ( vapnp ) procedure , in which the bcs or hfb wavefunction is projected onto good particle number before the variation is done @xcite . effectively , the pair condensate wavefunction [ eq . ( [ gs ] ) ]
is taken as the variational ground state . |
7,675 | Suppose that you have an abstract for a scientific paper: a stress exists in solids surfaces , similarly to liquids , also if the underlying bulk material is stress - free .
this paper investigates the surface stress effect on the measured value of the si lattice parameter used to determine the avogadro constant by counting si atoms .
an elastic - film model has been used to provide a surface load in a finite element analysis of the lattice strain of the x - ray interferometer crystal used to measure the lattice parameter .
eventually , an experiment is proposed to work a lattice parameter measurement out so that there is a visible effect of the surface stress . .
And you have already written the first three sentences of the full article: the avogadro constant , @xmath0 , is determined by dividing the molar volume of a silicon single - crystal highly enriched with @xmath1si by its unit cell volume , obtained from the measured value of the lattice parameter @xcite .
the lattice parameter is measured by means of combined x - ray and optical interferometry .
recently , the effect of surface stress was brought to our attention as a possible error source in our measurement of the lattice parameter @xcite ..
Please generate the next two sentences of the article | indeed , this issue was already taken into account but never definitely investigated @xcite . an intrinsic surface - stress exists in solid , in a similar way
as it occurs in liquids , which was first modelled by gibbs @xcite and shuttleworth @xcite , whose works were seminal in surface thermodynamics . |
7,676 | Suppose that you have an abstract for a scientific paper: out of plane vibrations are suppressed in graphene layers placed on a substrate .
these vibrations , in suspended samples , are relevant for the understanding of properties such as the electrical resistivity , the thermal expansion coefficient , and other .
we use a general framework to study the properties of the out of plane mode in graphene on different substrates , taking into account the dynamics of the substrate .
we discuss broadening of this mode and how it hybridizes with the substrate rayleigh mode , comparing our model with experimental observations .
we use the model to estimate the substrate induced changes in the thermal expansion coefficient and in the temperature dependence of the electrical resistivity . .
And you have already written the first three sentences of the full article: since its isolation in 2004 @xcite , graphene , a monolayer of carbon atoms arranged in a honeycomb lattice , has received great attention due to both its unique electrical and mechanical properties @xcite . in graphene , the carbon atoms display an sp@xmath0 hybridization , with the out of plane p@xmath1 orbitals forming a @xmath2 band which is responsible for its electrical properties , while the sp@xmath0 orbitals form strong @xmath3 in plane bonds that govern its mechanical properties .
it has been verified both experimentally and theoretically @xcite that graphene is the known material with the largest in plane elastic constants .
in freely suspended graphene samples the vibrations of the lattice can be classified into in plane and out of plane ( flexural ) modes , with the flexural mode lying at lower energies and showing a quadratic dispersion ..
Please generate the next two sentences of the article | anharmonic effects at long wavelengths strongly couple in plane and flexural modes @xcite .
the flexural mode is responsible for the significant temperature dependence of the electronic resistivity at low temperatures @xcite . |
7,677 | Suppose that you have an abstract for a scientific paper: the large area telescope ( lat ) on the _ fermi _ satellite is the first @xmath0-ray instrument to discover pulsars directly via their @xmath0-ray emission .
roughly one third of the 117 @xmath0-ray pulsars detected by the lat in its first three years were discovered in blind searches of @xmath0-ray data and most of these are undetectable with current radio telescopes .
i review some of the key lat results and highlight the specific challenges faced in @xmath0-ray ( compared to radio ) searches , most of which stem from the long , sparse data sets and the broad , energy - dependent point - spread function ( psf ) of the lat .
i discuss some ongoing lat searches for @xmath0-ray millisecond pulsars ( msps ) and @xmath0-ray pulsars around the galactic center .
finally , i outline the prospects for future @xmath0-ray pulsar discoveries as the lat enters its extended mission phase , including advantages of a possible modification of the lat observing profile . .
And you have already written the first three sentences of the full article: in the first four decades since their discovery , pulsars were almost the exclusive domain of radio ( and to a lesser extent x - ray ) astronomy .
indeed , of the @xmath12000 known pulsars , the majority were discovered in radio . since june 2008 ,
however , with the launch of the lat , on the _ fermi _ satellite , @xmath0-rays have become a viable means of discovering ( and studying ) pulsars ..
Please generate the next two sentences of the article | more important than the number of lat - detected pulsars ( a small fraction of the overall population ) , the lat sample is subject to different biases than the radio sample .
lat pulsars are typically nearby ( @xmath1few kpc ) and energetic ( @xmath2 erg s@xmath3 ) , and a large fraction are _ radio - quiet_. furthermore , @xmath0-rays , unlike the radio beams , carry a significant fraction of the rotational energy of pulsars , thus providing a powerful probe into these extreme objects . |
7,678 | Suppose that you have an abstract for a scientific paper: the implications of a large value of the effective majorana neutrino mass for a class of two texture zero neutrino mass matrices have been studied in the flavor basis .
it is found that these textures predict near maximal atmospheric neutrino mixing angle in the limit of large effective majorana neutrino mass .
it is noted that this prediction is independent of the values of solar and reactor neutrino mixing angles .
we present the symmetry realization of these textures using the discrete cyclic group @xmath0 .
it is found that the texture zeros realised in this work remain stable under renormalization group running of the neutrino mass matrix from the seesaw scale to the electroweak scale , at one loop level . .
And you have already written the first three sentences of the full article: the flavor mixing pattern in the lepton sector is quite different from the mixing pattern in the quark sector . in the quark sector ,
one of the mixing angles is around @xmath1 and the other two mixing angles are very small whereas in the lepton sector two of the mixing angles ( atmospheric mixing angle @xmath2 and solar mixing angle @xmath3 ) are large and the third mixing angle ( reactor mixing angle @xmath4 ) which was recently measured in a number of neutrino oscillation experiments @xcite is around @xmath5 . to explain the mixing pattern in the lepton sector ,
a number of theoretical ideas have been proposed ..
Please generate the next two sentences of the article | a particular approach for explaining the lepton flavor mixing pattern is based on non - abelian discrete symmetries which predict values of mixing matrix elements independent of the lepton masses and are known as mass independent textures .
some typical mixing patterns obtained using the above approach are tribimaximal mixing @xcite , bimaximal mixing @xcite , golden ratio - i @xcite , golden ratio - ii @xcite , hexagonal mixing @xcite all of which predict a vanishing reactor mixing angle . however , in the light of recent experimental data @xcite , these mixing patterns need modifications . |
7,679 | Suppose that you have an abstract for a scientific paper: a pedagogical approach for deriving the statistical mechanical partition function , in a manner that emphasizes the key role of entropy in connecting the microscopic states to thermodynamics , is introduced .
the connections between the combinatoric formula @xmath0 applied to the gibbs construction , the gibbs entropy , @xmath1 , and the microcanonical entropy expression @xmath2 are clarified .
the condition for microcanonical equilibrium , and the associated role of the entropy in the thermodynamic potential is shown to arise naturally from the postulate of equal _ a priori _ states .
the derivation of the canonical partition function follows simply by invoking the gibbs ensemble construction at constant temperature and using the first and second law of thermodynamics ( _ via _ the fundamental equation @xmath3 ) that incorporate the conditions of conservation of energy and composition without the needs for explicit constraints ; other ensemble follow easily .
the central role of the entropy in establishing equilibrium for a given ensemble emerges naturally from the current approach .
connections to generalized ensemble theory also arise and are presented in this context . .
And you have already written the first three sentences of the full article: in deriving the partition function for a desired ensemble , the most common approach is to maximize an entropy function with constraints appropriate to the thermodynamic condition . while equivalent to the approach proposed below , such a method ( called the traditional approach hereafter ) does not make clear to students the explicit role of the assumption of equal _ a priori _ states and the corresponding role of the entropy in the thermodynamic potential for the microcanonical ensemble .
indeed , @xmath2 is often taken as a postulate@xcite and its connection to the statistical formula @xmath4 ( appearing on boltzmann s tombstone ) is not obvious .
further , in the traditional approach , the role of the entropy in understanding equilibrium in non - isolated , open ensembles can be confusing ..
Please generate the next two sentences of the article | we note in passing that concerns over the rigor of the method of most probable distribution prompted darwin and fowler to develop a derivation of the partition function based upon complex analysis.@xcite also , infrequently stressed is the gibbs entropy , @xmath1 , where @xmath5 is the probability of finding a system in a given state , which can be invoked for any equilibrium ensemble and associated state probabilities.@xcite it is a direct consequence of the statistical entropy formula , @xmath4 , in conjunction with the gibbs construction of an ensemble that contains a large number of macroscopic subsystems , each consistent with the desired thermodynamic variables ; @xmath6 gives the number of possible realizations within the gibbs construction for the ensemble under consideration .
the gibbs entropy also permits the derivation of the connection between the characteristic thermodynamic function and the partition function for a given ensemble without further appeal to thermodynamic expressions , as is required in the traditional approach . in the present approach , |
7,680 | Suppose that you have an abstract for a scientific paper: we consider large mimo systems , where by ` _ large _ '
we mean number of transmit and receive antennas of the order of tens to hundreds .
such large mimo systems will be of immense interest because of the very high spectral efficiencies possible in such systems .
we present a low - complexity detector which achieves uncoded near - exponential diversity performance for hundreds of antennas ( i.e. , achieves near siso awgn performance in a large mimo fading environment ) with an average per - bit complexity of just @xmath0 , where @xmath1 and @xmath2 denote the number of transmit and receive antennas , respectively . with an outer turbo code ,
the proposed detector achieves good coded bit error performance as well .
for example , in a 600 transmit and 600 receive antennas v - blast system with a high spectral efficiency of 200 bps / hz ( using bpsk and rate-1/3 turbo code ) , our simulation results show that the proposed detector performs close to within about 4.6 db from theoretical capacity .
we also adopt the proposed detector for the low - complexity decoding of high - rate non - orthogonal space - time block codes ( stbc ) from division algebras ( da ) .
for example , we have decoded the @xmath3 full - rate non - orthogonal stbc from da using the proposed detector and show that it performs close to within about 5.5 db of the capacity using 4-qam and rate-3/4 turbo code at a spectral efficiency of 24 bps / hz . the practical feasibility of the proposed high - performance low - complexity detector could potentially trigger wide interest in the implementation of large mimo systems .
we also illustrate the applicability of the proposed detector in the low - complexity detection of large multicarrier cdma ( mc - cdma ) systems . in large mc - cdma systems with hundreds of users ,
the proposed detector is shown to achieve near single - user performance at an average per - bit complexity linear in number of users , which is quite appealing for its use in practical cdma systems .
large....
And you have already written the first three sentences of the full article: -input multiple - output ( mimo ) techniques offer transmit diversity and high data rates through the use of multiple antennas at both transmitter and receiver sides @xcite-@xcite .
a key component of a mimo system is the mimo detector at the receiver , which , in practice , is often the bottleneck for the overall performance and complexity .
mimo detectors including sphere decoder and several of its variants @xcite-@xcite achieve near maximum likelihood ( ml ) performance at the cost of high complexity ..
Please generate the next two sentences of the article | other well known detectors including zf ( zero forcing ) , mmse ( minimum mean square error ) , and zf - sic ( zf with successive interference cancellation ) detectors @xcite,@xcite are attractive from a complexity view point , but achieve relatively poor performance .
for example , the zf - sic detector ( i.e. , the well known v - blast detector with ordering @xcite,@xcite ) does not achieve the full diversity in the system . the mmse - sic detector has been shown to achieve optimal performance @xcite . however , these detectors are prohibitively complex for large number of antennas of the order of tens to hundreds . with small number of antennas , the high capacity potential of mimo |
7,681 | Suppose that you have an abstract for a scientific paper: it has been known that at least some of the observed gamma - ray bursts ( grbs ) are produced at cosmological distances and the grb production rate may follow the star formation rate .
we model the batse detected intensity distribution of long grbs in order to determine their space density distribution and opening angle distribution .
our main results are : the lower and upper distance limits to the grb production are @xmath0 and @xmath1 , respectively ; the grb opening angle follows exponential distribution and the mean opening angle is about 0.03 radian ; the peak luminosity appears a better standard candle than the total energy of a grb . .
And you have already written the first three sentences of the full article: recent research results indicate that radiation from gamma - ray bursts ( grbs ) may be constrained mostly in narrow beams @xcite , which suggests that grbs may be standard candles at cosmological distances @xcite .
previous studies of the grb space density distribution suggested that grb production rate may follow the observed star formation rate for small values of redshift @xcite , but may increase monotonically for very high values of redshift @xcite ; however neither the lower limit nor the upper limit of redshift for grb production could be determined reliably previously because these studies are either limited by statistics or have to rely on some empirical relationships between some statistical properties of selected samples of grbs . because both the space density distribution and beaming effect play important roles for the observed grb intensity distribution , here we make use of the batse / cgro grb intensity distribution , which is the largest sample of grbs collected so far , to determine directly the grb space density and opening angle distribution
for the grb space density distribution , we assume the following model , under the cosmological parameters of @xmath2 , @xmath3 km s@xmath4 mpc@xmath4 and @xmath5 , in order to compare with previous star formation rate measurements @xcite ..
Please generate the next two sentences of the article | @xmath6 the functional form is taken from the measured star formation rate @xcite with @xmath7 and @xmath8 .
our main goal in this paper is to determine @xmath9 and @xmath10 for grbs from the observed grb intensity distribution , in order to answer the question where in the universe grbs are produced predominantly . for the grb opening angle distribution , we study three cases when the grb opening angle @xmath11 follows gaussian , exponential , or power - law distributions . for a gaussian distribution of @xmath11 , |
7,682 | Suppose that you have an abstract for a scientific paper: the current paper is the second part of a series of two papers dedicated to 2d problem of diffraction of acoustic waves by a segment bearing impedance boundary conditions . in the first part
some preliminary steps were made , namely , the problem was reduced to two matrix riemann
hilbert problem . here
the riemann
hilbert problems are solved with the help of a novel method of oe equations .
each riemann hilbert problem is embedded into a family of similar problems with the same coefficient and growth condition , but with some other cuts .
the family is indexed by an artificial parameter .
it is proven that the dependence of the solution on this parameter can be described by a simple ordinary differential equation ( ode1 ) .
the boundary conditions for this equation are known and the inverse problem of reconstruction of the coefficient of ode1 from the boundary conditions is formulated .
this problem is called the oe equation . the oe
equation is solved by a simple numerical algorithm . .
And you have already written the first three sentences of the full article: this paper is the second part of a big work dedicated to diffraction of a plane wave by a thin infinite impedance strip . in @xcite ( which will be referred to as part
i hereafter ) some preliminary steps were made .
namely , the diffraction problem was formulated and symmetrized ..
Please generate the next two sentences of the article | functional problems of the wiener
hopf class with entire functions were introduced . using the method of embedding formula these problems |
7,683 | Suppose that you have an abstract for a scientific paper: we determine the wavefunctions of electrons bound to a positively charged mesoscopic metallic cluster covered by an insulating surface layer .
the radius of the metal core and the thickness of the insulating surface layer are of the order of a couple of ngstrm .
we study in particular the electromagnetic decay of externally located electrons into unoccupied internally located states which exhibits a resonance behaviour .
this resonance structure has the consequence that the lifetime of the `` mesoscopic atoms '' may vary by up to 6 orders of magnitude depending on the values of the parameters ( from sec to years ) . .
And you have already written the first three sentences of the full article: clusters consisting of some 10@xmath0 to 10@xmath1 atoms , which can be produced for instance in the course of the condensation of vapour , have attracted great interest during the last 20 years .
these mesoscopic clusters were found to exhibit classical as well as quantum mechanical features . in the special case of metallic clusters @xcite ,
the conduction electrons , which move in the average potential produced by the positively charged ions , exhibit shell effects . as a consequence ,.
Please generate the next two sentences of the article | the binding energy of the cluster becomes a function of the number of free electrons ( and thus also of the number of ions ) . in turn , this implies measurable variations of the formation probability of a cluster as a function of its mass in a thermal vapour - gas equilibrium .
other interesting types of mesoscopic systems are the so - called fullerenes which represent a crystal of atoms covering a closed , usually spherical surface @xcite . |
7,684 | Suppose that you have an abstract for a scientific paper: we study the stoke s efficiency and it s fluctuating properties in the case of a spatial asymmetric ratchet potential with a temporal asymmetric driving force from adiabatic to nonadiabatic regime .
our numerical investigations show that the average stoke s efficiency and the average current decrease with the frequency of driving .
for low frequency of driving , i.e. , in the case of an adiabatic regime , we reproduced the analytical results supporting our numerical simulations . by evaluating the probability distribution , @xmath0 for stoke s efficiency , @xmath1 we focus on the stochastic properties of stokes efficiency .
we find that in most of the parameter space , fluctuations in @xmath1 are comparable to or larger than the mean values . in such a situation
one has to study the full probability distribution of @xmath1 .
with increase in frequency of driving , the distribution becomes multipeaked . at the same time the average stoke s efficiency decreases with increase in frequency of drive . for high frequency of driving ,
the distribution develops a peak across zero .
further increase in frequency this peak gets sharper . and finally at sufficiently high frequency we get a strong peak across zero indicating that there is no effective transport in this regime .
.5 cm _ keywords_:ratchets , efficiency , fluctuations .
And you have already written the first three sentences of the full article: over the last several decades the study of interplay of noise and nonlinearity has become a major subject of research in various multidisciplinary areas@xcite .
these studies include the noise induced directed transport , stochastic resonance , noise induced stability of unstable states , noise induced phase transition , noise induced ordering etc . in most of the above mentioned cases the presence of noise is very much essential . in the literature ,
the noise induced directed transport in periodic extended structures in the absence of overall net bias has been extensively studied ..
Please generate the next two sentences of the article | two basic ingredients are required for the posilibity of such directed transport , namely , the system should be driven out of equilibrium and there should be some asymmetry ( either temporal or spatial ) along with nonlinearity in the system .
the systems consisting of brownian particles and operating with the minimal conditions for such directed transport are known as brownian ratchets / brownian motors @xcite . |
7,685 | Suppose that you have an abstract for a scientific paper: one of the main results in canonical quantum gravity is the introduction of spin network states as a basis on the space of kinematical states .
to arrive at the physical state space of the theory though we need to understand the dynamics of the quantum gravitational states . to this aim
we study a model in which we allow for the spins , labeling the edges of spin networks , to change according to simple rules .
the gauge invariance of the theory , restricting the possible values for the spins , induces propagating modes of spin changes .
we investigate these modes under various assumptions about the parameters of the model . .
And you have already written the first three sentences of the full article: there are two very important issues in the loop approach to non - perturbative canonical quantum gravity@xcite , which we have to address in our quest for a complete theory .
the first is the problem of evolution of the gravitational quantum states and the second one is the recovery of the classical continuous space from the discrete structures which appear at very short scale .
the problem of evolution in canonical quantum gravity is quite non - trivial ..
Please generate the next two sentences of the article | the underlying general covariance principle of the theory leads not to a true hamiltonian , but to a sum of constraints .
the physical states of the theory are then the ones which are annihilated by these constraints . imposing the gauge and the diffeomorphism constraints has led to a hilbert space |
7,686 | Suppose that you have an abstract for a scientific paper: it is shown that a simple bcs model with a quadrupole - quadrupole interaction provides a consistent description of the measured quadrupole moments of a sequence of odd mass sn and cd isotopes and allows the extraction of the neutron single particle occupation probabilities . .
And you have already written the first three sentences of the full article: in a recent high accuracy experimental study of electric quadrupole and magnetic dipole moments of a sequence of odd - mass cd isotopes @xcite it was noted that the electric quadrupole moments of the @xmath0 states in the cd isotopes vary linearly with neutron number and are very simply and very well described in terms of a @xmath1 orbital sequentially occupied in the seniority scheme with a large neutron effective charge @xmath2 . if this is so , the same simple physics should be manifest in the other presumed single quasi - particle states in cd and , a - fortiori , in the the sn isotopes which have a closed proton shell .
the idea that the single neutron occupation probabilities can be so simply extracted from electromagnetic properties is sufficiently attractive to warrant a more detailed second look .
the aim of this paper is to show that this can be done using a minimalist theoretical framework ..
Please generate the next two sentences of the article | ultimately of course , large scale theoretical calculations , shell model or beyond - mean - field model , are required to describe the structure of these nuclei , including their electromagnetic properties .
the aim of this paper is much more modest , but the picture is nevertheless useful for its simplicty . |
7,687 | Suppose that you have an abstract for a scientific paper: we extend a theory of first order @xmath0 corrections to gutzwiller s trace formula for systems with a smooth potential to systems with discrete symmetries and , as an example , apply the method to the two - dimensional hydrogen atom in a uniform magnetic field .
we exploit the @xmath1-symmetry of the system in the calculation of the correction terms .
the numerical results for the semiclassical values will be compared with values extracted from exact quantum mechanical calculations .
the comparison shows an excellent agreement and demonstrates the power of the @xmath0 expansion method . , , and semiclassical theories , gutzwiller s trace formula , @xmath0 expansions , discrete symmetries , diamagnetic hydrogen atom 03.65.sq , 05.45.mt .
And you have already written the first three sentences of the full article: semiclassical theories have become very important for a deeper understanding of quantum systems , and gutzwiller s trace formula @xcite has become a powerful tool for classically chaotic systems .
it provides a semiclassical approximation of the quantum level density in terms of classical periodic orbits . in a systematic expansion of the level density in powers of
@xmath0 it can be considered as the leading order ..
Please generate the next two sentences of the article | higher orders of this asymptotic expansion have been developed in several studies @xcite , but for a long time were only tested for billiard systems , i.e. , systems with hard walls instead of smooth potentials . by extending an expansion which was derived by gaspard et al .
@xcite , grmaud @xcite developed @xmath0 corrections to gutzwiller s trace formula for quantum systems with a smooth potential . |
7,688 | Suppose that you have an abstract for a scientific paper: we develop , from first principles , a general and compact formalism for predicting the electromagnetic response of a metamaterial with non - magnetic inclusions in the long wavelength limit , including spatial dispersion up to the second order . specifically , by resorting to a suitable multiscale technique ,
we show that medium effective permittivity tensor and the first and second order tensors describing spatial dispersion can be evaluated by averaging suitable spatially rapidly - varying fields each satysifing electrostatic - like equations within the metamaterial unit cell . for metamaterials with negligible second - order spatial dispersion
, we exploit the equivalence of first - order spatial dispersion and reciprocal bianisotropic electromagnetic response to deduce a simple expression for the metamaterial chirality tensor .
such an expression allows us to systematically analyze the effect of the composite spatial symmetry properties on electromagnetic chirality .
we find that even if a metamaterial is geometrically achiral , i.e. it is indistinguishable from its mirror image , it shows pseudo - chiral - omega electromagnetic chirality if the rotation needed to restore the dielectric profile after the reflection is either a @xmath0 or @xmath1 rotation around an axis orthogonal to the reflection plane .
these two symmetric situations encompass two - dimensional and one - dimensional metamaterials with chiral response . as an example admitting full analytical description ,
we discuss one - dimensional metamaterials whose single chirality parameter is shown to be directly related to the metamaterial dielectric profile by quadratures . .
And you have already written the first three sentences of the full article: designing the electromagnetic response of an artificial medium is one of the main target of modern photonics and metamaterial science is probably the most important research field based on such skill .
basically the design is made possible by the physical fact that the electromagnetic field , when traveling within a nonhomogeneous medium with sub - wavelength features , is not able to follow its spatial rapidly - varying details so that the field only experiences the effect of an averaged or effective medium .
a number of different homogenization approaches have been developed for predicting the effective medium electromagnetic response and they exploit different and suitable approximation schemes . the simplest homogenization technique deals with the retrieval of the effective parameters from the scattering properties of the medium @xcite and it is based on postulating the equivalence between a complex metamaterial array and a uniform slab of same thickness with unknown constitutive parameters ..
Please generate the next two sentences of the article | another homogenization technique is the field averaging method which is based on the averaging of the electromagnetic field in a metamaterial unit cell @xcite and , in analogy with the retrieval technique , it is a numerical method for the determination of effective parameters .
in addition to numerical methods , mean - field homegenization theories are available where the effective parameters are evaluated from the distribution of the underlying metamaterial inclusions . |
7,689 | Suppose that you have an abstract for a scientific paper: we model lagrangian lateral mixing and transport of passive scalars in meandering oceanic jet currents by two - dimensional advection equations with a kinematic stream function with a time - dependent amplitude of a meander imposed .
the advection in such a model is known to be chaotic in a wide range of the meander s characteristics .
we study chaotic transport in a stochastic layer and show that it is anomalous .
the geometry of mixing is examined and shown to be fractal - like .
the scattering characteristics ( trapping time of advected particles and the number of their rotations around elliptical points ) are found to have a hierarchical fractal structure as functions of initial particle s positions .
a correspondence between the evolution of material lines in the flow and elements of the fractal is established .
chaotic advection , meandering jet , fractals 47.52.+j,47.53.+n , 92.10.ty .
And you have already written the first three sentences of the full article: major western boundary currents in the ocean are meandering jets separating water masses with different physical and biogeochemical characteristics .
the prominent examples are the gulf stream in the atlantic ocean and the kuroshio in the pacific ocean . these and similar `` heat engines '' define the climate in large regions of the planet .
similar jets in the stratosphere play important role in transport and distribution of chemical substances . from the hydrodynamic point of view.
Please generate the next two sentences of the article | , they may be considered as jet flows with running waves of different wave lengths and phase velocities imposed .
the simplest kinematic model of such a flow is a two - dimensional jet of an ideal fluid with a given velocity profile that is perturbed by an amplitude - modulated wave traveling from the west to the east . |
7,690 | Suppose that you have an abstract for a scientific paper: motion of protein drops on crystallization media during routine handling is a major factor affecting the reproducibility of crystallization conditions .
drop stability can be enhanced by chemical patterning to more effectively pin the drop s contact line . as an example
, a hydrophilic area is patterned on an initially flat hydrophobic glass slide .
the drop remains confined to the hydrophilic area , and the maximum drop size that remains stable when the slide is rotated to the vertical position increases .
this simple method is readily scalable and has the potential to significantly improve outcomes in hanging and sitting drop crystallization . .
And you have already written the first three sentences of the full article: sitting- and hanging - drop vapor diffusion methods are among the most popular techniques for protein crystallization ( hampton research co. , 2003 ; mcpherson , 1999 ) . in the sitting drop technique , protein crystals can sediment onto the glass or plastic surface supporting the drop , frequently adhering so strongly that they are damaged during retrieval .
adhered crystals are much more likely to crack during growth because of stresses associated with contact with the support .
the hanging drop method largely eliminates these problems ..
Please generate the next two sentences of the article | crystals sediment away from the supporting surface toward the liquid - air interface ( although some may still nucleate and grow on the supporting surface ) .
freely suspended crystals often have unperturbed facets , show less cracking and have smaller mosaicities , and ( in the absence of protein `` skins '' ) are easily retrieved for diffraction studies . |
7,691 | Suppose that you have an abstract for a scientific paper: for smooth manifolds equipped with various geometric structures , we construct complexes that replace the de rham complex in providing an alternative fine resolution of the sheaf of locally constant functions . in case
that the geometric structure is that of a parabolic geometry , our complexes coincide with the bernstein - gelfand - gelfand complex associated with the trivial representation .
however , at least in the cases we discuss , our constructions are relatively simple and avoid most of the machinery of parabolic geometry . moreover
, our method extends to contact and symplectic geometries ( beyond the parabolic realm ) . .
And you have already written the first three sentences of the full article: in @xcite , ap , slovk , and souek construct sequences of invariant differential operators on _ parabolic geometries _ of any type @xmath0 , one for each finite - dimensional representation @xmath1 of @xmath2 .
( here , @xmath2 is a semisimple lie group and @xmath3 a parabolic subgroup . )
these sequences are known as _ bernstein - gelfand - gelfand _ ( bgg ) sequences since , for the homogeneous model @xmath0 of such a geometry , these sequences are complexes , which are dual to a parallel construction due to these authors @xcite on the level of verma modules . in @xcite calderbank and diemer.
Please generate the next two sentences of the article | simplify the construction of bgg sequences in @xcite .
in addition they provide @xcite , for regular parabolic geometries , alternative bgg sequences , which only coincide with the ones in @xcite if the geometry is _ torsion - free_. the latter sequences not only appear to be more natural , they also have the advantage that if @xmath1 is taken to be the trivial representation , then they form complexes , providing fine resolutions of the locally constant sheaf @xmath4 ( as one sees by suitably modifying ( * ? ? ? * proposition 5.5(iv ) ) ) . for the sequences of @xcite |
7,692 | Suppose that you have an abstract for a scientific paper: the pierre auger observatory in malarge , argentina , is designed to study the origin of ultrahigh energy cosmic rays with energies above @xmath0ev .
the energy calibration of the detector is based on a system of four air fluorescence detectors . to obtain reliable calorimetric information from the fluorescence stations ,
the atmospheric conditions at the experiment s site need to be monitored continuously during operation .
one of the components of the observatory s atmospheric monitoring system is a set of four elastic backscatter lidar stations , one station at each of the fluorescence detector sites .
this paper describes the design , current status , standard operation procedure , and performance of the lidar system of the pierre auger observatory . , , , , , , , , , , , , , , , , , , , , , , , , , , , , , and ultrahigh energy cosmic rays ; air fluorescence detectors ; atmospheric monitoring ; lidar 07.60.-j , 42.68.wt , 92.60.-e , 96.50.sd .
And you have already written the first three sentences of the full article: the pierre auger observatory in malarge , argentina , the world s largest facility to detect ultrahigh energy cosmic rays with energies above @xmath0ev , is currently nearing completion .
data collection started in january 2004 , and the observatory has already accumulated an ultrahigh energy cosmic ray data set of unprecedented size . due to their extremely low flux , primary cosmic rays at ultrahigh energies can not be observed directly .
rather , they enter the atmosphere and interact with air molecules , inducing a cascade of secondary particles , called an extensive air shower ..
Please generate the next two sentences of the article | the properties of the primary particle ( energy , arrival direction , and chemical composition ) have to be deduced from indirect measurements of the extensive air shower .
two detector types have traditionally been used to measure air showers : surface detectors , which detect the particles of the air shower cascade that reach the ground ; and air fluorescence detectors , which make use of the fact that the particles in the air shower excite air molecules , causing uv fluorescence . |
7,693 | Suppose that you have an abstract for a scientific paper: in recent years , indirect evidence has emerged suggesting that many nearby non - active galaxies harbor quiescent supermassive black holes .
knowledge of the frequency of occurrence of black holes , of their masses and spins , is of broad relevance for studying black hole growth and galaxy and agn formation and evolution .
it has been suggested that an unavoidable consequence of the existence of supermassive black holes , and the best diagnostic of their presence in non - active galaxies , would be occasional tidal disruption of stars captured by the black holes .
these events manifest themselves in form of luminous flares powered by accretion of debris from the disrupted star into the black hole .
candidate events among optically non - active galaxies emerged in the past few years .
for the first time , we have looked with high spatial and spectral resolution at one of these most extreme variability events ever recorded among galaxies . here ,
we report measuring a factor @xmath0 drop in luminosity of the x - ray source rxj12421119 with the x - ray observatories _ chandra _ and _ xmm - newton _ , and perform key tests of the favored outburst scenario , tidal disruption of a star by a supermassive black hole .
we show that the detected `` low - state '' emission has properties such that it must still be related to the flare .
the power - law shaped post - flare x - ray spectrum indicates a `` hardening '' compared to outburst .
the inferred black hole mass , the amount of liberated energy , and the duration of the event favor an accretion event of the form expected from the ( partial or complete ) tidal disruption of a star . .
And you have already written the first three sentences of the full article: the x - ray luminous nuclei of active galaxies ( agn ) are believed to be powered by accretion of gas onto supermassive black holes . there is now growing evidence that many nearby _ non - active _ galaxies harbor quiescent , weakly or non - accreting black holes ( see reviews by kormendy & gebhardt 2001 ; richstone 2002 ) .
studies of the abundance of black holes , of their masses and their spins , shed light on the mechanisms of black hole growth and of galaxy and agn formation and evolution .
possibly the most direct means of detecting supermassive black holes at the centers of galaxies , and an unavoidable consequence of their existence , would be occasional tidal disruption of stars and subsequent accretion of their debris by these supermassive black holes ( e.g. , hills 1975 ; gurzadyan & ozernoi 1979 ; carter & luminet 1982 ; rees 1988 , 1990 ; wang & merritt 2004 ) ..
Please generate the next two sentences of the article | the events would appear as luminous flares of radiation emitted when the stellar debris is accreted by the black hole .
stellar capture and disruption is apart from accretion of gas and black hole merging one of the three major processes studied in the context of black hole growth ( e.g. , frank & rees 1976 ) . |
7,694 | Suppose that you have an abstract for a scientific paper: we have adapted the anelastic spectral code of @xcite to simulate a turbulent convective layer with the intention of studying the effectiveness of turbulent eddies in dissipating external shear ( e.g. tides ) .
we derive the anelastic equations , show the time integration scheme we use to evolve these equations and present the tests we ran to confirm that our code does what we expect .
further we apply a perturbative approach to find an approximate scaling of the effective eddy viscosity with frequency , and find that it is in general agreement with an estimate obtained by applying the same procedure to a realistic simulation of the upper layers of the solar convective zone .
hydrodynamics , anelastic approximation , stratified flows , shear flows , spectral methods , convection , turbulence , turbulent dissipation , effective viscosity .
And you have already written the first three sentences of the full article: dissipation of stellar tides and oscillations is often considered to be mainly due to the turbulent flow in their convective zones .
usually the effects of the turbulent flow are parametrized by some sort of effective viscosity coefficient .
clearly the situation is not as simple as that and the usual `` fix '' is to allow this viscosity coefficient to depend on the perturbation being dissipated , most notably its frequency and perhaps direction of the shear it creates ..
Please generate the next two sentences of the article | completely analytical treatments start by assuming a kolmogorov spectrum for the turbulent flow and combine it with some prescription for the effectiveness of eddies in dissipating perturbations of the given period . since kolmogorov turbulence is isotropic the direction of shear is unimportant in such prescriptions .
two such prescriptions have been used . |
7,695 | Suppose that you have an abstract for a scientific paper: we study the effects of rayleigh and raman scattering on the formation of polarized spectral lines in a @xmath0-type multi - term atom .
we fully take into account the partial redistribution of frequency and the presence of atomic polarization in the lower states of the atomic model .
problems that can be modeled with this formalism include , for example , the formation of the h - k and ir triplet , the analogous system of , and the ly@xmath1-h@xmath2 system of hydrogenic ions . .
And you have already written the first three sentences of the full article: many resonance lines of the solar spectrum show complex linear polarization patterns , especially when observed near the solar limb @xcite .
these signals are generated by scattering in the upper photosphere and chromosphere , where the plasma is very rarefied and nearly collisionless , and long integration paths are involved in the production of the observed polarized signals . under these conditions ,
the ground state of the observed transitions may harbour a significant amount of atomic polarization @xcite , and coherence effects among the atomic levels become apparent in the emergent polarization profiles ( e.g. , * ? ? ?.
Please generate the next two sentences of the article | * ; * ? ? ?
* ; * ? ? ? |
7,696 | Suppose that you have an abstract for a scientific paper: discretized landscapes can be mapped onto ranked surfaces , where every element ( site or bond ) has a unique rank associated with its corresponding relative height .
by sequentially allocating these elements according to their ranks and systematically preventing the occupation of bridges , namely elements that , if occupied , would provide global connectivity , we disclose that bridges hide a new tricritical point at an occupation fraction @xmath0 , where @xmath1 is the percolation threshold of random percolation . for any value of @xmath2 in the interval @xmath3 ,
our results show that the set of bridges has a fractal dimension @xmath4 in two dimensions . in the limit @xmath5
, a self - similar fracture is revealed as a singly connected line that divides the system in two domains .
we then unveil how several seemingly unrelated physical models tumble into the same universality class and also present results for higher dimensions .
any real landscape can be duly coarse - grained and represented as a two - dimensional _ discretized map _ of regular cells ( e.g. , a square lattice of sites or bonds ) to which average heights can be associated .
this process is exemplarily shown in figs .
[ fig::rank](a)-(c ) . as such
, the concept of discretized maps has been considered as a way to delimit spatial boundaries in a wide range of seemingly unrelated problems , ranging from tracing water basins and river networks in landscapes @xcite to the identification of cancerous cells in human tissues @xcite , and the study of spatial competition in multispecies ecosystems @xcite . moreover , previous studies have shown that cracks or surviving paths through discretized maps possess a universal fractal dimension which can be physically realized in terms of optimal paths under strong disorder @xcite , optimal path cracks @xcite , loopless percolation @xcite , or minimum spanning trees @xcite . here
we show that all these problems can be understood in terms of the same universal concept of _ fracturing....
And you have already written the first three sentences of the full article: we performed simulations of fracturing ranked surfaces on square lattices .
it is worth noting that , despite the similarities with random percolation , the suppressing of connectivity poses a statistically different problem .
for example , while for @xmath13 there is only a single configuration in random percolation ( all bonds occupied ) , in ranked percolation there are @xmath14 , evenly weighted , possible configurations , where @xmath15 is the total number of bonds . in classical percolation.
Please generate the next two sentences of the article | the total number of configurations is @xmath16 .
figure [ fig::mbbsize ] shows the dependence of the number of bridge bonds @xmath17 on system size , for different fractions of occupied bonds , namely , @xmath18 , @xmath19 , and @xmath20 . |
7,697 | Suppose that you have an abstract for a scientific paper: we present the final release of the multi - wavelength _ xmm_-lss data set , covering the full survey area of 11.1 square degrees , with x - ray data processed with the latest _
xmm_-lss pipeline version .
the present publication supersedes the @xcite catalogue pertaining to the initial 5 @xmath0 .
we provide x - ray source lists in the customary energy bands ( 0.5 - 2 and 2 - 10 kev ) for a total of 6721 objects in the deep full - exposure catalogue and 5572 in the 10ks - limited one , above a detection likelihood of 15 in at least one band .
we also provide a multiwavelength catalogue , cross - correlating our list with ir , nir , optical and uv catalogues .
customary data products ( x - ray fits images , cfhtls and swire thumbnail images ) are made available together with our interactively queriable database in milan , while a static snapshot of the catalogues has been supplied to cds .
[ firstpage ] catalogues , surveys , x - rays : general .
And you have already written the first three sentences of the full article: the rationale for the _ xmm_-large scale structure ( _ xmm_-lss ) survey was presented in @xcite . a first catalogue for the 5.5 @xmath0 surveyed until year 2003 was presented in ( * ? ? ?
* hereafter paper i ) . in the present paper
, we supersede the first release with a new version which covers the entire 11.1 @xmath0area of the survey ..
Please generate the next two sentences of the article | all the data were processed or re - processed afresh with the latest version of our pipeline ( see section [ secxamin ] ) .
we release two families of x - ray database tables ( see section [ seconline ] ) , a standard catalogue ( termed 2xlss ) for event files truncated to a common uniform exposure of 10 ks , and a _ deeper _ catalogue ( termed 2xlssd ) using the full exposure time . the _ xmm_-lss survey area , located around @xmath1 @xmath2 , was covered in the optical band by the canada france hawaii telescope legacy survey wide and deep synoptic fields ( cfhtls - w1 and d1 ) ; in the nir band partially by the ukirt infrared deep sky survey ( ukidss ; @xcite ) ; in the ir by the _ |
7,698 | Suppose that you have an abstract for a scientific paper: we derive an exact deterministic nonlinear observer to compute the continuous state of an inertial navigation system based on partial discrete measurements , the so - called strapdown problem .
nonlinear contraction is used as the main analysis tool , and the hierarchical structure of the system physics is sytematically exploited .
the paper also discusses the use of nonlinear measurements , such as distances to time - varying reference points . .
And you have already written the first three sentences of the full article: this paper derives an exact deterministic nonlinear observer to compute the continuous state of an inertial navigation system based on partial discrete measurements .
the main analysis tool is nonlinear contraction theory @xcite .
recent work on nonlinear observer design for mechanical systems based on nonlinear contraction theory can be found in @xcite ..
Please generate the next two sentences of the article | specifically , we consider the classical strap - down problem in inertial navigation @xcite , where angular position ( euler angles ) @xmath0 and inertial position * r * are computed from the body turn rate @xmath1 and inertial acceleration @xmath2 , measured continuously in intrinsic ( body - fixed ) coordinates , @xmath3 with @xmath4\ ] ] and @xmath5\ ] ] as made precise in @xcite such a system lies at the boundary between convergence and divergence , much like a triple integrator . in this paper ,
the continuous measurements of @xmath1 and @xmath2 are augmented by _ |
7,699 | Suppose that you have an abstract for a scientific paper: we use observations made with the upgraded arecibo 305 m telescope in august 1998 to obtain accurate spin vector determinations for 54 nearly edge - on galaxies in the minnesota automated plate scanner pisces - perseus survey ( maps - pp ) .
we introduce a simple observational technique of determining the sense of rotation for galaxies , even when their disks are not fully resolved .
we examined the spin vector distribution of these 54 galaxies for evidence of preferential galaxy alignments .
we use the kuiper statistic , a variant of the kolmogorov
smirnov statistic , to determine the significance of any anisotropies in the distribution of galaxy spin vectors .
the possibility of `` spin vector domains '' is also investigated .
we find no significant evidence of preferential galaxy alignments in this sample .
however , we show that the small sample size places weak limits on the level of galaxy alignments . .
And you have already written the first three sentences of the full article: the search for galaxy alignments has a long history , beginning with searches for alignments in `` spiral and elliptical nebulae '' during the late 19th century .
recent scrutiny of the problem has been motivated by the understanding that establishing the level of galaxy spin vector ( @xmath0 ) alignments could offer an additional constraint on various theories of galaxy formation and evolution .
for example , `` top - down '' scenarios of large - scale structure formation can lead to ordered distributions of angular momentum on cluster and supercluster scales through a variety of mechanisms ( @xcite , @xcite , @xcite , @xcite ) ..
Please generate the next two sentences of the article | in addition to galaxy @xmath0 alignments resulting from various formation mechanisms , galaxy @xmath0 alignments may also be the evolutionary result of anisotropic merger histories ( @xcite ) , galaxy - galaxy interactions ( @xcite ) , or strong gravitational gradients ( @xcite , @xcite ) . for a summary of the history of the field , see djorgovski ( 1987 ) and cabanela & aldering ( 1998 ) [ hereafter paper i ] .
observational support exists for some forms of galaxy @xmath0 alignments with surrounding large - scale structure . |
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