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9,700 | Suppose that you have an abstract for a scientific paper: we present calculations of ground state properties of spherical , doubly closed - shell nuclei from @xmath0o to @xmath1pb employing the techniques of many - body perturbation theory using a separable density dependent monopole interaction .
the model gives results in hartree - fock order which are of similar quality to other effective density - dependent interactions .
in addition , second and third order perturbation corrections to the binding energy are calculated and are found to contribute small , but non - negligible corrections beyond the mean - field result .
the perturbation series converges quickly , suggesting that this method may be used to calculate fully correlated wavefunctions with only second or third order perturbation theory .
we discuss the quality of the results and suggest possible methods of improvement . .
And you have already written the first three sentences of the full article: the central problem of nuclear structure theory is the solution of the many - body schrdinger equation ( mbse ) . for hamiltionans of interest in the nuclear case ,
an analytic solution is impossible , and one is compelled to use some approximation , either in the numerical solution of the equation or the specification of the hamiltonian , or both . approaching the problem with the aim of using as realistic a representation of the potential as possible usually means fitting a combination of a meson exchange and phenomenological interaction to low - energy nucleon - nucleon scattering data and properties of few - body systems . to get good agreement with experiment both two- and
three - body forces seem to be necessary ..
Please generate the next two sentences of the article | recent examples of such potentials include the bonn @xcite , the argonne two - body @xcite with urbanna 3-body@xcite , nijmegen @xcite and moscow @xcite potentials , the last of which also incorporates quark degrees of freedom .
these forces share the property of having a hard repulsive core which is a natural consequence of meson - exchange . |
9,701 | Suppose that you have an abstract for a scientific paper: we have developed the _ general method _ for the description of _ separatrix chaos _ , basing on the analysis of the separatrix map dynamics . matching it with the resonant hamiltonian analysis ,
we show that , for a given amplitude of perturbation , the maximum width of the chaotic layer in energy may be much larger than it was assumed before .
we apply the above theory to explain the drastic facilitation of global chaos onset in time - periodically perturbed hamiltonian systems possessing two or more separatrices , previously discovered ( prl 90 , 174101 ( 2003 ) ) .
the theory well agrees with simulations .
we also discuss generalizations and applications .
examples of applications of the facilitation include : the increase of the dc conductivity in spatially periodic structures , the reduction of activation barriers for noise - induced transitions and the related acceleration of spatial diffusion , the facilitation of the stochastic web formation in a wave - driven or kicked oscillator . .
And you have already written the first three sentences of the full article: a weak perturbation of a hamiltonian system causes the onset of chaotic layers around separatrices of the unperturbed system and/or separatrices surrounding nonlinear resonances generated by the perturbation @xcite .
the system may be transported along the layer in a random - like fashion and this chaotic transport plays an important role in many physical phenomena @xcite . if the perturbation is sufficiently weak , then the layers are thin and the chaos is called _ local _ @xcite
. as the perturbation magnitude increases , the width of the layer grows and the layers corresponding to adjacent separatrices reconnect at some , typically non - small , critical value of the perturbation ..
Please generate the next two sentences of the article | this conventionally marks the onset of _ global _ chaos @xcite i.e. chaos in a large region of the phase space , with chaotic transport throughout the whole relevant energy range .
the reconnection of the layers around separatrices of the resonances often correlates with the overlap in energy between neighbouring resonances calculated independently in the resonant approximation . |
9,702 | Suppose that you have an abstract for a scientific paper: we review some practical aspects of measuring the amplitude of variability in ` red noise ' light curves typical of those from active galactic nuclei ( agn ) .
the quantities commonly used to estimate the variability amplitude in agn light curves , such as the fractional rms variability amplitude , @xmath0 , and excess variance , @xmath1 , are examined .
their statistical properties , relationship to the power spectrum , and uses for investigating the nature of the variability processes are discussed .
we demonstrate that @xmath1 ( or similarly @xmath0 ) shows large changes from one part of the light curve to the next , even when the variability is produced by a stationary process .
this limits the usefulness of these estimators for quantifying differences in variability amplitude between different sources or from epoch to epoch in one source .
some examples of the expected scatter in the variance are tabulated for various typical power spectral shapes , based on monte carlo simulations .
the excess variance can be useful for comparing the variability amplitudes of light curves in different energy bands from the same observation .
monte carlo simulations are used to derive a description of the uncertainty in the amplitude expected between different energy bands ( due to measurement errors ) .
finally , these estimators are used to demonstrate some variability properties of the bright seyfert 1 galaxy markarian 766 .
the source is found to show a strong , linear correlation between rms amplitude and flux , and to show significant spectral variability .
[ firstpage ] galaxies : active galaxies : seyfert galaxies : individual ( ) x - rays : galaxies methods : data analysis .
And you have already written the first three sentences of the full article: one of the defining characteristics of active galactic nuclei ( agn ) is that their x - ray emission is variable .
x - ray light curves from seyfert 1 galaxies show unpredictable and seemingly aperiodic variability ( lawrence et al . 1987 ; m@xmath2hardy 1989 ) .
such random variability is often referred to as _ noise _ , meaning that it is the result of a stochastic , as opposed to deterministic , process . in this context.
Please generate the next two sentences of the article | the ` noise ' is intrinsic to the source and not a result of measurement errors ( such as poisson noise ) , i.e. the signal itself is the output of a noise process .
one of the most common tools for examining agn variability ( and noise processes in general ) is the fluctuation power spectral density ( psd ) which represents the amount of variability power ( mean of the squared amplitude ) as a function of temporal frequency ( timescale@xmath3 ) . |
9,703 | Suppose that you have an abstract for a scientific paper: we describe a scheme for efficient large - scale electronic - structure calculations based on the combination of the pole expansion and selected inversion ( pexsi ) technique with the siesta method , which uses numerical atomic orbitals within the kohn - sham density functional theory ( ksdft ) framework .
the pexsi technique can efficiently utilize the sparsity pattern of the hamiltonian and overlap matrices generated in siesta , and for large systems has a much lower computational complexity than that associated with the matrix diagonalization procedure .
the pexsi technique can be used to evaluate the electron density , free energy , atomic forces , density of states and local density of states without computing any eigenvalue or eigenvector of the kohn - sham hamiltonian .
it can achieve accuracy fully comparable to that obtained from a matrix diagonalization procedure for general systems , including metallic systems at low temperature .
the pexsi method is also highly scalable . with the recently developed massively parallel pexsi technique , we can make efficient use of more than @xmath0 processors on high performance machines .
we demonstrate the performance and accuracy of the siesta - pexsi method using several examples of large scale electronic structure calculations , including 1d , 2d and bulk problems with insulating , semi - metallic , and metallic character . .
And you have already written the first three sentences of the full article: kohn - sham density functional theory ( ksdft ) is the most widely used framework for electronic - structure calculations , and plays an important role in the analysis of electronic , structural and optical properties of molecules , solids and nano - structures .
the efficiency of ksdft depends largely on the computational cost associated with the evaluation of the electron charge density for a given potential within a self - consistent field ( scf ) iteration .
the most straightforward way to perform such an evaluation is to partially diagonalize the kohn - sham hamiltonian by computing a set of eigenvectors corresponding to the algebraically smallest eigenvalues of the hamiltonian ..
Please generate the next two sentences of the article | the complexity of this approach is @xmath1 , where @xmath2 is the number of electrons in the atomistic system of interest . as the number of atoms or electrons in the system increases , the cost of diagonalization becomes prohibitively expensive .
although linear scaling algorithms @xcite are attractive alternatives for improving the efficiency of ksdft , they rely on using the nearsightedness principle @xcite , which asserts that the density perturbation induced by a local change in the external potential decays away from where the perturbation is applied . |
9,704 | Suppose that you have an abstract for a scientific paper: we present some recent findings concerning the use of rr lyrae as distance indicators and stellar tracers .
we outline pros and cons of field and cluster rr lyrae stars and discuss recent theoretical findings concerning the use of the bailey ( amplitude vs pulsation period ) diagram to constrain the possible occurrence of helium enhanced rr lyrae stars .
nonlinear , convective rr lyrae models indicate that the pulsation properties of rr lyrae stars are minimally affected by the helium content .
the main difference between canonical and he enhanced models is due to the increase in luminosity predicted by evolutionary models .
moreover , we focus our attention on the near - infrared period - luminosity ( pl ) relation of rr lyrae and summarize observational evidence concerning the slope of the k - band pl relation in a few globulars ( m92 , reticulum , m5 , @xmath0 cen ) covering a range in metallicity of @xmath11 dex .
current findings suggest that the slope has a mild dependence on the metal content when moving from the metal - poor to the metal - intermediate regime .
finally , we also discuss the use of rr lyrae stars either to estimate ( helium indicator : a - parameter ) or to measure ( absorption and emission lines ) the helium content .
[ 1996/06/01 ] 2@xmath2 2c ii 4c iv 2fe ii 3fe iii 1 mg i 2 mg ii 2si ii 4si iv 2al ii 3al iii 1o i 1n
i 1h i = .
And you have already written the first three sentences of the full article: even after a cursory reading of the papers published in the seminal vatican conference on stellar populations it becomes clear the key role that rr lyrae played in the development of what we now call stellar populations and in the shaping of galactic structure .
their relevance is also supported by the first sentence of one the papers given by w. baade at that conference : _ variable stars , in particular the cepheids and the cluster - type variables , have becoming increasingly important in the exploration of our own and other galaxies . _ the relevance of rr lyrae stars in stellar astrophysics is further supported by the fact that rr lyrae are the most popular old , low - mass distance indicators . in early times
it was assumed that their mean luminosity was constant , but soon after the spectroscopic investigations showed that they do obey a visual magnitude metallicity relation ..
Please generate the next two sentences of the article | therefore , the knowledge of their metallicity was fundamental for accurate estimates of their individual distances . however , high - resolution spectroscopy in single slit mode was prohibitive for large numbers of rr lyrae stars .
the @xmath3s method invented by george @xcite opened a new path in the extensive use of field rr lyrae as stellar tracers of the galactic halo @xcite and of the bulge @xcite . |
9,705 | Suppose that you have an abstract for a scientific paper: * context : * for many years , we have observed industry struggling in defining a high quality requirements engineering ( re ) and researchers trying to understand industrial expectations and problems .
although we are investigating the discipline with a plethora of empirical studies , those studies either concentrate on validating specific methods or on single companies or countries .
therefore , they allow only for limited empirical generalisations .
* objective : * to lay an empirical and generalisable foundation about the state of the practice in re , we aim at a series of open and reproducible surveys that allow us to steer future research in a problem - driven manner .
* method : * we designed a globally distributed family of surveys in joint collaborations with different researchers from different countries .
the instrument is based on an initial theory inferred from available studies . as a long - term goal ,
the survey will be regularly replicated to manifest a clear understanding on the status quo and practical needs in re . in this paper , we present the design of the family of surveys and first results of its start in germany .
* results : * our first results contain responses from 30 german companies .
the results are not yet generalisable , but already indicate several trends and problems . for instance , a commonly stated problem respondents see in their company standards are artefacts being underrepresented , and important problems they experience in their projects are incomplete and inconsistent requirements .
* conclusion : * the results suggest that the survey design and instrument are well - suited to be replicated and , thereby , to create a generalisable empirical basis of re in practice .
1000000 1000000 .
And you have already written the first three sentences of the full article: requirements engineering ( re ) is a discipline that constitutes a holistic key to successful development projects as the elicitation , specification and validation of precise and stakeholder - appropriate requirements are critical determinants of quality @xcite . at the same time , re is characterised by the involvement of interdisciplinary stakeholders and uncertainty as many things are not clear from the beginning of a project .
hence , re is highly volatile and inherently complex by nature .
although the importance of a high quality re and its continuos improvement has been recognised for many years , we can still observe industry struggling in defining and applying a high quality re @xcite ..
Please generate the next two sentences of the article | the diversity of how re is performed in various industrial environments , each having its particularities in the domains of application or the software process models used , dooms the discipline to be not only a process area difficult to improve , but also difficult to investigate for common practices and shortcomings . from a researcher s perspective
, experimental research in re thereby becomes a crucial and challenging task . |
9,706 | Suppose that you have an abstract for a scientific paper: we present results demonstrating the occurrence of changes in the collective dynamics of a hamiltonian system which describes a confined microplasma characterized by long range coulomb interactions . in its lower energy regime , we first detect macroscopically , the transition from a `` crystalline like '' to a `` liquid like '' behavior , which we call the `` melting transition '' .
we then proceed to study this transition using a microscopic chaos indicator called the _ smaller alignment index _
( sali ) , which utilizes two deviation vectors in the tangent dynamics of the flow and is nearly constant for ordered ( quasi periodic ) orbits , while it decays exponentially to zero for chaotic orbits as @xmath0 , where @xmath1 are the two largest lyapunov exponents . during the `` melting phase '' , sali exhibits a peculiar , stair like decay to zero , reminiscent of `` sticky '' orbits of hamiltonian systems near the boundaries of resonance islands
this alerts us to the importance of the @xmath2 variations in that regime and helps us identify the energy range over which `` melting '' occurs as a multi stage diffusion process through weakly chaotic layers in the phase space of the microplasma .
additional evidence supporting further the above findings is given by examining the @xmath3 indices , which generalize sali ( = @xmath4 ) to the case of @xmath5 deviation vectors and depend on the complete spectrum of lyapunov exponents of the tangent flow about the reference orbit .
@xmath6interdisciplinary center for nonlinear phenomena and complex systems ( cenoli ) , service de physique des systmes complexes et mcanique statistique , + universit libre de bruxelles , 1050 , brussels , belgium + @xmath7center for research and applications of nonlinear systems ( crans ) , + department of mathematics , + university of patras , 26500 , patras , greece .
And you have already written the first three sentences of the full article: it has long been established that microscopic deterministic chaos provides an efficient mechanism for the mixing of orbits in the phase
space of dynamical systems , leading to the decay of statistical correlations as time evolves .
thus , chaotic dynamics can magnify small scale fluctuations and justify the existence of macroscopic variables like entropy and temperature , which are of central importance in an analysis based on non equilibrium statistical mechanics @xcite ..
Please generate the next two sentences of the article | the main purpose of the work presented here is to study the `` melting transition '' in a microplasma model , using standard methods , as well as certain recently developed techniques for chaos detection , such as the _ smaller alignment index _ ( sali ) @xcite and its extension to the so called _ generalized alignment index _ ( gali ) @xcite .
this latter approach is based on geometrical aspects of the microscopic dynamics and has significant computational advantages over more classical indicators based either on local dynamics , such as the lyapunov exponents , or statistical properties , such as the mean temperature or the kolmogorov |
9,707 | Suppose that you have an abstract for a scientific paper: we compute lyapunov vectors ( lvs ) corresponding to the largest lyapunov exponents in delay - differential equations with large time delay .
we find that characteristic lvs , and backward ( gram - schmidt ) lvs , exhibit long - range correlations , identical to those already observed in dissipative extended systems .
in addition we give numerical and theoretical support to the hypothesis that the main lv belongs , under a suitable transformation , to the universality class of the kardar - parisi - zhang equation .
these facts indicate that in the large delay limit ( an important class of ) delayed equations behave exactly as dissipative systems with spatiotemporal chaos . .
And you have already written the first three sentences of the full article: delayed dynamical systems ( ddss ) serve to model diverse phenomena in physics @xcite ( prominently in optics ) , but also in other fields @xcite such as engineering , biology , climatology or ecology .
more than one decade ago @xcite it was found that delayed systems with one constant delay can be studied like extended systems , and they present not only analogies but equivalent phenomena such as pattern instabilities @xcite and high - dimensional chaos @xcite .
chaos in ddss is considered as a particular type of spatio - temporal chaos for which the delay plays the role of the system size ..
Please generate the next two sentences of the article | there are a number of studies concerning the tangent dynamics of systems with time delay .
previous works mainly focused on the lyapunov exponents ( les ) and properties obtained from them ( dimension , entropy , ... ) @xcite . |
9,708 | Suppose that you have an abstract for a scientific paper: heavier resonances are continually being added to the hadronic spectrum from the particle data group that follow an exponentially increasing mass spectrum .
however , it has been suggested that even further states predicted from quark models are needed in the hadronic spectrum in order to improve the agreement between the hadron resonance gas model predictions and lattice qcd data .
we find that the inclusion of such states with extrapolated branching ratios slightly decreases the freezeout temperature . to eliminate ambiguities , we introduce a first principle method to extract the freeze - out temperature for charged kaons from experimental data , which yields a lower bound of @xmath0145 mev for the highest collision energy at rhic . .
And you have already written the first three sentences of the full article: the hadron resonance gas model has been extremely successful in reproducing lattice quantum chromodynamics results in the hadron gas phase @xcite .
the underlying assumption is that it is possible to describe an interacting gas of hadrons in the ground states through a non - interacting gas of hadrons and resonances .
the expression for thermodynamic quantities in the hrg model is then simply a sum over the contributions from each resonance . in this sense ,.
Please generate the next two sentences of the article | the only `` variable '' in the model is the hadronic spectrum one feeds into it .
the original idea by rolf hagedorn was that a limiting temperature @xmath1 for matter exists , called hagedorn temperature , which can not be exceeded , and therefore a system of hadrons responds to an arbitrary increase in the energy density by creating more and more resonances rather than by increasing the temperature @xcite . |
9,709 | Suppose that you have an abstract for a scientific paper: it is shown that in models including the standard electroweak theory and for some particular values of the underlying parameters , electric currents can be spontaneously generated in cosmic strings , without the need of any external field ( e.g. , electric or magnetic ) as is required in most models .
this mechanism is then shown to break spontaneously the lorentz invariance along the initially goto - nambu string . the characteristic time needed for the current to build up
is estimated and found to lowest order to depend only on the mass of the intermediate @xmath0 vector boson and the fine structure constant . .
And you have already written the first three sentences of the full article: cosmic strings @xcite are linear vortex defects predicted to be formed at a cosmological phase transition during which the vacuum manifold would not be simply connected .
the first interest in studying them comes from the fact that since a typical grand unified theory ( gut ) predicts a few phase transitions ( whose order , as far as the strings are concerned , does actually not matter @xcite ) , and because the vacuum structure needed to form strings happens to be generically realized , one can , following vilenkin @xcite , reasonnably assume that cosmic strings have an existence probability of at least @xmath1 . although they are not the only possible topological defects that could be formed in such phase transitions , they have the advantage , as compared for instance with domain walls and monopoles which must be somehow inflated away @xcite , to be at present compatible ( as are as well the textures @xcite ) with all existent cosmological data @xcite , while being also possibly responsible for the formation of large scale structure @xcite and the observed anisotropies in the cosmic microwave background ( cmbr ) @xcite .
most models based on these strings assume that they are generated at the gut phase transition , so that the dimensionless parameter @xmath2 , with @xmath3 the newton constant and @xmath4 the energy per unit string length , giving the expected relative order of magnitude of any gravitational effect due to these strings ( e.g. , light deflection @xcite or cmbr temperature fluctuations @xcite ) , was assumed to be @xmath5 ..
Please generate the next two sentences of the article | another kind of strings was proposed by witten @xcite in 1985 who pointed out the possibility that bosonic or fermionic superconducting currents could be trapped in the strings , thereby inducing many electromagnetic effects , such as , for instance , a new scenario for structure formation @xcite .
shortly thereafter , it was shown by davis and shellard @xcite and independently by carter @xcite that , although the regular strings can not be potentially responsible for a cosmological catastrophe ( i.e. , the remnant mass density would not exceed the critical density ) because of gravitational radiation and the absence of any stabilising mechanism , the situation was completely different for current - carrying string loops since in the latter case , there exists centrifugally supported equilibrium configurations ( called vortons @xcite or rings @xcite ) which would overfill the universe @xcite by many orders of magnitude if they were stable ( a point which still demands further clarification and is presently under investigation @xcite ) , this stabilizing mechanism being enhanced when electromagnetic corrections are taken into account @xcite , and should not be confused with the much less efficient `` spring '' , or magnetostatic support mechanism @xcite . |
9,710 | Suppose that you have an abstract for a scientific paper: we investigate resonant spin - flavor ( rsf ) conversions of supernova neutrinos which are induced by the interaction of neutrino magnetic moment and supernova magnetic fields . from the formulation which includes all three - flavor neutrinos and anti - neutrinos , we give a new crossing diagram that includes not only ordinary msw resonance but
also magnetically - induced rsf effect . with the diagram , it is found that four conversions occur in supernova , two are induced by the rsf effect and two by the pure msw .
we also numerically calculate neutrino conversions in supernova matter , using neutrino mixing parameters inferred from recent experimental results and a realistic supernova progenitor model .
the results indicate that until 0.5 seconds after core bounce , the rsf - induced @xmath0 transition occurs efficiently ( adiabatic resonance ) , when @xmath1 , where @xmath2 is the strength of the magnetic field at the surface of iron core .
we also evaluate the energy spectrum as a function of @xmath3 at the superkamiokande detector and the sudbury neutrino observatory using the calculated conversion probabilities , and find that the spectral deformation might have possibility to provide useful information on neutrino magnetic moment as well as magnetic field strength in supernovae . .
And you have already written the first three sentences of the full article: the properties of neutrinos attract a strong attention since neutrinos alone are the elementary particles showing the evidence of new physics beyond the standard model . in particular
, recent experiments of the superkamiokande ( sk ) detector @xcite and the sudbury neutrino observatory ( sno ) @xcite have shown that neutrino have non - zero mass and mixing angles by solar @xcite and atmospheric @xcite neutrino data .
these neutrino oscillation experiments enable us to constrain the squared mass difference between mass eigenstates and mixing angles ..
Please generate the next two sentences of the article | the solar neutrino experiments strongly support the matter - induced large mixing angle ( lma ) solution ( @xmath4 @xcite ) and the atmospheric neutrino experiments have proved that @xmath5 and @xmath6 are maximally mixing ( @xmath7 @xcite ) .
however , there are several parameters which are not sufficiently constrained . |
9,711 | Suppose that you have an abstract for a scientific paper: this paper proposes and discusses a test of the chemical composition of ultra - high energy cosmic rays that relies on the anisotropy patterns measured as a function of energy . in particular
, we show that if one records an anisotropy signal produced by heavy nuclei of charge @xmath0 above an energy @xmath1 , one should record an even stronger ( possibly much stronger ) anisotropy at energies @xmath2 due to the proton component that is expected to be associated with the sources of the heavy nuclei .
this conclusion remains robust with respect to the parameters characterizing the sources and it does not depend at all on the modelling of astrophysical magnetic fields . as a concrete example , we apply this test to the most recent data of the pierre auger observatory . assuming that the anisotropy reported above 55 eev is not a statistical accident , and that no significant anisotropy has been observed at energies @xmath3eev , we show that the apparent clustering toward cen a can not be attributed to heavy nuclei .
similar conclusions are drawn regarding the apparent excess correlation with nearby active galactic nuclei .
we then discuss a robust lower bound to the magnetic luminosity that a source must possess in order to be able to accelerate particles of charge @xmath0 up to @xmath4eev , @xmath5erg / s . using this bound in conjunction with the above conclusions
, we argue that the current pao data does not support the model of cosmic ray origin in active radio - quiet or even radio - loud galaxies .
finally , we demonstrate that the apparent clustering in the direction of cen a can be explained by the contribution of the last few gamma - ray bursts or magnetars in the host galaxy thanks to the scattering of the cosmic rays on the magnetized lobes . .
And you have already written the first three sentences of the full article: the sources of ultra - high energy cosmic rays have remained elusive in spite of the enormous progress reached on the experimental side , with present day detectors reaching apertures @xmath6km@xmath7 sr yr .
the differential energy spectrum , the chemical composition and the distribution of arrival directions on the sky are as many clues to the nature of the source .
there is now a consensus on the existence of the gzk cut - off ( greisen 1966 ; zatsepin & kuzmin 1966 ) , which has been observed by two different experiments ( abbasi et al ..
Please generate the next two sentences of the article | 2008 , abraham et al .
the existence of this gzk cut - off puts on solid ground the models which attribute the origin of ultra - high energy cosmic rays to powerful astrophysical objects distributed on cosmological scales , such as powerful radio - galaxies ( rachen & biermann 1993 ) , gamma - ray bursts ( milgrom & usov 1995 , vietri 1995 , waxman 1995 ) , or magnetars ( arons 2003 ) . |
9,712 | Suppose that you have an abstract for a scientific paper: the main uncertainty in current determinations of the power spectrum normalization , @xmath0 , from abundances of x - ray luminous galaxy clusters arises from the calibration of the mass temperature relation .
we use our weak lensing mass determinations of 30 clusters from the hitherto largest sample of clusters with lensing masses , combined with x - ray temperature data from the literature , to calibrate the normalization of this relation at a temperature of 8 kev , @xmath1 .
this normalization is consistent with previous lensing - based results based on smaller cluster samples , and with some predictions from numerical simulations , but higher than most normalizations based on x - ray derived cluster masses .
assuming the theoretically expected slope @xmath2 of the mass temperature relation , we derive @xmath3 for a spatially - flat @xmath4cdm universe with @xmath5 .
the main systematic errors on the lensing masses result from extrapolating the cluster masses beyond the field - of - view used for the gravitational lensing measurements , and from the separation of cluster / background galaxies , contributing each with a scatter of 20% . taking this into account ,
there is still significant intrinsic scatter in the mass temperature relation indicating that this relation may not be very tight , at least at the high mass end .
furthermore , we find that dynamically relaxed clusters are @xmath6 hotter than non - relaxed clusters . .
And you have already written the first three sentences of the full article: the abundance of massive clusters of galaxies provides sensitive constraints on the cosmological parameters that govern structure growth in the universe .
however , a prerequisite for this is reliable mass measurements for large samples of clusters with well - understood selection criteria .
cluster mass measurements used have traditionally come from virial analysis of the velocity dispersion measurements of cluster galaxies ( e.g. , frenk et al ..
Please generate the next two sentences of the article | 1990 ; carlberg et al . 1997 ; borgani et al . 1999 ) , or x - ray temperature measurements of the hot intra - cluster gas under the assumption that the gas is in hydrostatic equilibrium ( for a review see * ? ? ?
satellite observatories such as rosat , asca , xmm - newton and _ chandra _ have made increasingly accurate x - ray temperature measurements of clusters , and have produced well - defined cluster samples of sufficient size to accurately measure the x - ray temperature and luminosity functions ( e.g. * ? ? ? |
9,713 | Suppose that you have an abstract for a scientific paper: the binary millisecond radio pulsar psr j1023 + 0038 has been recently the subject of multi - wavelength monitoring campaigns which revealed that an accretion disc has formed around the neutron star ( since 2013 june ) .
we present here the results of x - ray and uv observations carried out by the _ swift _ satellite between 2013 october and 2014 may , and of optical and nir observations performed with the rem telescope , the liverpool telescope , the 2.1-m telescope at the san pedro mrtir observatory and the 1.52-m telescope at the loiano observing station .
the x - ray spectrum is well described by an absorbed power law , which is softer than the previous quiescent epoch ( up to 2013 june ) .
the strong correlation between the x - ray and the uv emissions indicates that the same mechanism should be responsible for part of the emission in these bands .
optical and infrared photometric observations show that the companion star is strongly irradiated .
double - peaked emission lines in the optical spectra provide compelling evidence for the presence of an outer accretion disc too . the spectral energy distribution from ir to x - rays is well modelled if the contributions from the companion , the disc and the intra - binary shock emission are all considered .
our extensive data set can be interpreted in terms of an engulfed radio pulsar : the radio pulsar is still active , but undetectable in the radio band due to a large amount of ionized material surrounding the compact object .
x - rays and gamma - rays are produced in an intra - binary shock front between the relativistic pulsar wind and matter from the companion and an outer accretion disc .
the intense spin - down power irradiates the disc and the companion star , accounting for the uv and optical emissions .
[ firstpage ] stars : individual : psr j1023 + 0038 stars : neutron pulsars : general x - rays : binaries . .
And you have already written the first three sentences of the full article: first j102347.6 + 003841 ( hereafter j1023 ) was discovered by bond et al .
( 2002 ) in the radio band and initially classified as a magnetic cataclysmic variable .
optical studies revealed signs for the presence of an accretion disc in 2001 ( szkody et al . 2003 ; wang et al ..
Please generate the next two sentences of the article | 2009a ) , which led to identify this system as a neutron star low - mass x - ray binary ( lmxb ; thorstensen & armstrong 2005 ; homer et al .
no enhanced x - ray emission was reported . |
9,714 | Suppose that you have an abstract for a scientific paper: in this paper , we first describe how we can arrange any bodies on figure - eight without collision in a dense subset of @xmath0 $ ] after showing that the self - intersections of figure - eight will not happen in this subset .
then it is reasonable for us to consider the existence of generalized solutions and non - collision solutions with mixed - symmetries or with double - eight constraints , arising from figure - eight , for n - body problem .
all of the orbits we found numerically in section [ se7 ] have not been obtained by other authors as far as we know . to prove the existence of these new periodic solutions , the variational approach and critical point theory
are applied to the classical n - body equations . and along the line used in this paper
, one can construct other symmetric constraints on n - body problems and prove the existence of periodic solutions for them .
msc - class : 70f10 , 37c80 , 70g75 .
And you have already written the first three sentences of the full article: n - body problem is a classical problem in mathematics and celestial mechanics . since euler s collinear solutions and lagrange s equilateral triangle solutions , any more `` clearly '' ( including the existence and the shape of the orbit ) solutions
have not been found except figure - eight solution , a planer three - body orbits with equal masses , which was proved strictly by chenciner and montgomery in @xcite in 1999 .
this remarkable and interesting orbit arouse many authors curiosity in studying more choreography orbits or other interesting symmetric constraints acting on the orbits of n - body problems , see , etc ..
Please generate the next two sentences of the article | furthermore , some investigations of a possible star system in real space have been performed in practice ( see @xcite ) . among those authors studies ,
the variational approach and the theory of critical points perform an important role . by minimizing the lagrangian action on a space of loops symmetry with respect to a well - chosen symmetry group , which also has some simple conditions on it , |
9,715 | Suppose that you have an abstract for a scientific paper: we present high time resolution observations of single pulses from the vela pulsar ( psr b083345 ) made with a baseband recording system at observing frequencies of 660 and 1413 mhz .
we have discovered two startling features in the 1413 mhz single pulse data .
the first is the presence of giant micro - pulses which are confined to the leading edge of the pulse profile .
one of these pulses has a peak flux density in excess of 2500 jy , more than 40 times the integrated pulse peak .
the second new result is the presence of a large amplitude gaussian component on the trailing edge of the pulse profile .
this component can exceed the main pulse in intensity but is switched on only relatively rarely .
fluctutation spectra reveal a possible periodicity in this feature of 140 pulse periods .
unlike the rest of the profile , this component has low net polarization and emits predominantly in the orthogonal mode .
this feature appears to be unique to the vela pulsar .
we have also detected microstructure in the vela pulsar for the first time .
these same features are present in the 660 mhz data .
we suggest that the full width of the vela pulse profile might be as large as 10 ms but that the conal edges emit only rarely . .
And you have already written the first three sentences of the full article: the vela pulsar is one of the closest and brightest radio pulsars known .
polarization observations made shortly after its discovery showed that it is highly linearly polarized and that the position angle of the radiation followed an s - shape curve as a function of pulse longitude ( radhakrishnan & cooke 1969 ) .
this showed that the radio emission was related to the geometry of the magnetic field lines near the pole ..
Please generate the next two sentences of the article | the rotating vector model ( rvm ) of radhakrishnan & cooke has been extensively used in a large number of pulsars to obtain the spin axis - magnetic axis and the viewing angle - magnetic axis geometries . in the vela pulsar , the angle between the spin and magnetic axes ,
@xmath0 is estimated to lie between 60 and 90 , and the impact angle , @xmath1 is @xmath2 ( krishnamohan & downs 1983 ( hereafter kd83 ) ; lyne & manchester 1988 ; rankin 1993 ) . in the only detailed single pulse study of vela to have appeared in the ( recent ) literature , kd83 observed 87000 pulses at 2.3 ghz with a time resolution including dispersion smearing of 750@xmath3s . |
9,716 | Suppose that you have an abstract for a scientific paper: we made a multi - wavelength study of young massive star clusters ( yscs ) in the interacting galaxy arp 24 , using the optical and ultraviolet images from _ hubble space telescope _
( _ hst _ ) , sloan digital sky survey , and _ galaxy evolution explorer _ ; the mid - infrared images from _ spitzer space telescope _ ; and the narrow - band h@xmath0 image and optical spectra from the naoc 2.16 m telescope . based on the _ hst _ images
, we found that the brightest infrared knot in arp 24 is associated with a complex of five young massive star clusters , within a region of @xmath1 0.95@xmath2 radius ( 127pc ) in size .
the ages and masses of the star clusters in this complex and other regions were estimated using _
hst _
broadband photometries and the starburst99 synthesis models .
the star clusters in this complex are very young ( within ages of @xmath1 3 - 5 myr ) and massive ( masses of @xmath110@xmath3m@xmath4 ) .
the ionization parameter and metallicity of the complex were estimated using the emission line ratios , and the star formation rates were calculated using monochromatic 24@xmath5 m , fuv , and h@xmath0 line luminosities .
we speculate that arp 24 may formed by a retrograde fly - by encounter indicated by its one - armed appearance and fan - like structure , and the formation of the yscs in this galaxy is triggered by the interaction .
the clusters in the ysc complex may formed in a single giant molecular cloud simultaneously . from the ultraviolet to mid - infrared spectral energy distributions , we found that the region of the ysc complex is relatively bluer in optical and has higher 24@xmath5 m dust emission relative to the starlight and 8@xmath5 m emission .
this warm infrared color may due to strong uv radiation field or other mechanisms ( e.g. , shocks ) within this region which may destroy the polycyclic aromatic hydrocarbons and enhance the small grain emission at 24@xmath5 m . .
And you have already written the first three sentences of the full article: star formation in galaxies generally occurs in star clusters instead of isolated stars , at least 20@xmath6 and possibly all stars form in clusters or associations ( fall 2004 ) .
young massive star clusters ( yscs , with masses often @xmath7 10@xmath3m@xmath4 ) , which are thought to be the products of violent star - forming episodes triggered by galaxy collisions , mergers , and close encounters ( de grijs 2003,2004 , and references therein ) , or generally form in the disks of isolated spirals with higher efficiency in environments of high star formation rate ( larsen 2004a , and references therein ) , are important for studying the ongoing star formation , stellar populations , and the evolutionary histories of their parent galaxies .
yscs are thought to formed in giant molecular clouds ( gmcs ) , and concentrated in star - forming clumps ( over - dense regions , or cores ; e.g. , elmegreen 2004 ) ..
Please generate the next two sentences of the article | the majority of important studies of extragalactic star clusters in the last years have involved use of the _ hubble space telescope _ ( _ hst _ ) , with its unprecedented spatial resolution ( @xmath10.04@xmath2 ) and full uv / optical bands ( 0.1 - 1.0@xmath5 m ) access for studying stellar populations , in particular the blue coverage for age - dating young clusters ( e.g. , de grijs et al . 2003 ; larsen 2004b ) .
the ages and masses of star clusters can be estimated using color - magnitude and/or color - color diagrams and compared with stellar population synthesis models ( e.g. , johnson et al . |
9,717 | Suppose that you have an abstract for a scientific paper: we have studied the effect of dynamical correlations on the electronic structure of single co adatoms on graphene monolayers with a recently developed novel method for nanoscopic materials that combines density functional calculations with a fully dynamical treatment of the strongly interacting @xmath0-electrons .
the coupling of the co @xmath0-shell to the graphene substrate and hence the dynamic correlations are strongly dependent on the orbital symmetry and the system parameters ( temperature , distance of the adatom from the graphene sheet , gate voltage ) . when the kondo effect takes place , we find that the dynamical correlations give rise to strongly temperature - dependent peaks in the co @xmath0-spectra near the fermi level . moreover , we find that the kondo effect can be tuned by the application of a gate voltage .
it turns out that the position of the kondo peaks is pinned to the dirac points of graphene rather than to the chemical potential . .
And you have already written the first three sentences of the full article: since its recent discovery , graphene a monolayer of graphite has become the subject of intense research due to its peculiar electronic properties @xcite .
the unusual properties of graphene are largely a result of the linear dispersion of electron bands at low energies and its two - dimensionality .
this allows to describe the charge carriers in graphene as a two - dimensional gas of massless dirac - fermions ..
Please generate the next two sentences of the article | the unusual electronic properties and the fact that its chemical potential can easily be tuned by a gate voltage make graphene an ideal experimental testing ground for exotic physics as well as a promising basis for novel nano - electronics devices . for recent reviews of this rapidly developing field and additional references , see e.g. refs . .
graphene is also a good testing ground for exotic kondo physics@xcite : first , the linearly vanishing dos of graphene favours the formation of a local moment @xcite which is a necessary condition for kondo physics . also vacancies and edge defects in graphene have been predicted to give rise to magnetic moments @xcite . |
9,718 | Suppose that you have an abstract for a scientific paper: we present a theoretical study of the impact of an electrostatic field combined with non - resonant linearly polarized laser pulses on the rotational dynamics of linear molecules . within the rigid rotor approximation
, we solve the time - dependent schrdinger equation for several field configurations . using the ocs molecule as prototype
, the field - dressed dynamics is analyzed in detail for experimentally accessible static field strengths and laser pulses .
results for directional cosines are presented and compared to the predictions of the adiabatic theory .
we demonstrate that for prototypical field configuration used in current mixed - field orientation experiments , the molecular field dynamics is , in general , non - adiabatic , being mandatory a time - dependent description of these systems .
we investigate several field regimes identifying the sources of non - adiabatic effects , and provide the field parameters under which the adiabatic dynamics would be achieved . .
And you have already written the first three sentences of the full article: the creation of directional states of molecules represents an important tool to control and tailor the rotational degree of freedom .
when a molecule is oriented the molecular fixed axes are confined along laboratory fixed axes and its dipole moment is pointing in a particular direction . experimentally , the availability of oriented molecules provides a wealth of interesting applications in a variety of molecular sciences , such as in chemical reaction dynamics @xcite , photoelectron angular distributions @xcite , or high - order harmonic generation @xcite . due to this broad interest
, special efforts have been undertaken to create samples of oriented molecules and techniques based in the application of inhomogeneous @xcite , and homogeneous @xcite electric fields as well as homogeneous magnetic fields @xcite have been used ..
Please generate the next two sentences of the article | a major breakthrough came with the proposal by friedrich and herschbach @xcite of enhancing the orientation of polar molecules by exposing them to combined weak electrostatic and strong non - resonant radiative fields .
this theoretical prediction was done within an adiabatic picture assuming that the switching on time of the laser pulse is larger than the molecular rotational period . for linear molecules , |
9,719 | Suppose that you have an abstract for a scientific paper: we introduce geoplotlib , an open - source python toolbox for visualizing geographical data .
geoplotlib supports the development of hardware - accelerated interactive visualizations in pure python , and provides implementations of dot maps , kernel density estimation , spatial graphs , voronoi tesselation , shapefiles and many more common spatial visualizations .
we describe geoplotlib design , functionalities and use cases . .
And you have already written the first three sentences of the full article: geographical data visualization is a fundamental tool for communicating results related to geospatial analyses , and for generating hypotheses during exploratory data analysis @xcite .
the constantly increasing availability of geolocated data from social media , mobile devices and spatial databases implies that we need new tools for exploring , mining and visualizing large - scale spatial datasets .
the python programming language @xcite has been gaining attention as a data analysis tool in the scientific community @xcite thanks to the clarity and simplicity of its syntax , and due to an abundance of third - parties libraries e.g. within many disciplines including scientific computing @xcite , machine learning @xcite , bayesian modeling @xcite , neuroscience @xcite , and bioinformatics @xcite . currently , however , there is limited support for geographical visualization . here , we introduce geoplotlib , a python toolbox for visualizing geographical data ..
Please generate the next two sentences of the article | geoplotlib provides a simple yet powerful api to generate geographical visualizations on openstreetmap @xcite tiles .
we release geoplotlib as open - source software @xcite , accompanied by a rich set of examples and documentation . in the remainder of this paper |
9,720 | Suppose that you have an abstract for a scientific paper: the paper studies the interaction of lamb waves with the free edge of a plate .
the reflection coefficients of a lamb mode at a plate free edge are calculated using a semi - analytical method , as a function of frequency and angle of incidence .
the conversion between forward and backward lamb modes is thoroughly investigated .
it is shown that , at the zero - group velocity ( zgv ) frequency , the forward @xmath0 lamb mode fully converts into the backward @xmath1 lamb mode at normal incidence .
besides , this conversion is very efficient over most of the angular spectrum and remains dominant at frequencies just above the zgv - point .
this effect is observed experimentally on a duralumin plate .
firstly , the @xmath0 lamb mode is selectively generated using a transducer array , secondly the @xmath1 mode is excited using a single circular transducer .
the normal displacement field is probed with an interferometer .
the free edge is shown to retro - focus the incident wave at different depths depending on the wave number mismatch between the forward and backward propagating modes . in the vicinity of the zgv - point ,
wave numbers coincide and the wave is retro - reflected on the source . in this frequency range ,
the free edge acts as a perfect phase conjugating mirror . .
And you have already written the first three sentences of the full article: controlling the propagation of acoustic or elastic waves is of fundamental interest for many applications ranging from imaging the living and detecting hazardous components , to information processing and structural health monitoring . owing to this context
, the concept of negative refraction has received a great deal of attention for the last fifteen years . in a negative index material , the energy flow
as dictated by the poynting vector should be in the opposite direction to the wave vector @xcite ..
Please generate the next two sentences of the article | this property implies that at an interface between a positive and a negative index material sound is bent the unusual way relative to the normal . in this paper
, we consider a related phenomenon referred to as negative reflection . |
9,721 | Suppose that you have an abstract for a scientific paper: we prove that under @xmath0 scaling , the limiting distribution as @xmath1 of the free energy of sepplinen s log - gamma discrete directed polymer is gue tracy - widom . the main technical innovation we provide is a general identity between a class of @xmath2-fold contour integrals and a class of fredholm determinants . applying this identity to the integral formula proved in @xcite for the laplace transform of the log - gamma polymer partition function , we arrive at a fredholm determinant which lends itself to asymptotic analysis ( and thus yields the free energy limit theorem ) .
the fredholm determinant was anticipated in @xcite via the formalism of macdonald processes yet its rigorous proof was so far lacking because of the nontriviality of certain decay estimates required by that approach . .
And you have already written the first three sentences of the full article: the log - gamma polymer was introduced and studied by sepplinen @xcite .
let @xmath3 be a positive real .
a random variable @xmath4 has _ inverse - gamma distribution with parameter @xmath5 _ if it is supported on the positive reals where it has distribution @xmath6 we abbreviate this @xmath7 ..
Please generate the next two sentences of the article | the _ log - gamma polymer partition function _ with parameter @xmath8 is given by @xmath9 where @xmath10 is an up / right directed lattice path from the euclidean point @xmath11 to @xmath12 and where @xmath13 . in @xcite
it was proved that @xmath14 where @xmath15 and @xmath16 is a large constant . here |
9,722 | Suppose that you have an abstract for a scientific paper: we investigate the effects of flavor su(3)-symmetry breaking on the quark , gluon , and mixed quark - gluon condensates , based on the nonlocal effective chiral action from the instanton vacuum .
we take into account the effects of the flavor su(3 ) symmetry breaking in the effective chiral action , so that the dynamical quark mass depends on the current quark mass ( @xmath0 ) .
we compare the results of the present approach with those without the current quark mass dependence of the dynamical quark mass .
it is found that the result of the quark condensate is decreased by about 30 % as @xmath0 increases to 200 mev , while that of the quark - gluon mixed condensates is diminished by about @xmath1 .
we obtain the ratios of the quark and quark - gluon mixed condensates , respectively : @xmath2^{1/3}=0.75 $ ] and @xmath3^{1/5}=0.87 $ ] .
it turns out that the dimensional parameter @xmath4 . *
1 . *
understanding the qcd vacuum is very complicated , since both perturbative and non - perturbative fluctuations come into play . in particular ,
the quark and gluon condensates , being the lowest dimensional ones , characterize the non - perturbative structure of the qcd vacuum . the quark condensate is identified as the order parameter for spontaneous chiral - symmetry breaking ( s@xmath5sb ) which plays an essential role in describing low - energy phenomena of hadrons : in the qcd sum rule , these condensates come from the operator product expansion and are related to hadronic observables @xcite , while in chiral perturbation theory ( @xmath5pt ) , the free parameter @xmath6 is introduced in the mass term of the effective chiral lagrangian at the leading order @xcite measuring the strength of the quark condensate @xcite . on the other hand ,
the gluon condensate is not the order parameter but measures the vacuum energy density @xcite , which was first estimated by the charmonium sum rule @xcite .
while the quark and gluon condensates are well understood phenomenologically , higher....
And you have already written the first three sentences of the full article: the present work is supported by the korea research foundation grant funded by the korean government(moehrd ) ( krf-2006 - 312-c00507 ) .
the work of s.n . is supported by the brain korea 21 ( bk21 ) project in center of excellency for developing physics researchers of pusan national university , korea .
the authors are grateful to m. m. musakhanov for critical comments and discussions ..
Please generate the next two sentences of the article | 99 m. a. shifman , a. i. vainshtein and v. i. zakharov , nucl .
b * 147 * ( 1979 ) 385 ; nucl . |
9,723 | Suppose that you have an abstract for a scientific paper: based on the analysis of a large sample of rxte / pca observations of several black hole binaries in the low spectral state we show that a correlation exists between the spectral parameters and characteristic noise frequency . in particular , the amplitude of reflection increases and the slope of comptonized radiation steepens as the noise frequency increases .
we consider possible implications of these results on the accretion flow models and discuss a possible observational test aimed to discriminate between different geometries of the accretion flow .
accretion , accretion disks black hole physics stars : binaries : general stars : individual : cygnus x-1 , gx339 - 4 , gs1354 - 644 x - rays : general x - rays : stars comptonization of soft seed photons in a hot , optically thin electron cloud near the compact object is thought to produce the hard x ray radiation in the low spectral state of accreting black holes ( @xcite , @xcite ) .
the slope of the comptonized spectrum is governed by the ratio of the energy deposited into the electrons and the influx of the soft radiation into the comptonization region ; the lower the ratio the steeper the comptonized spectrum ( e.g. @xcite , @xcite , @xcite ) .
reflection of the comptonized radiation from neutral or partially ionized matter , presumably the optically thick accretion disk , leads to appearance of characteristic features in the spectra of x ray binaries ( fig.[plrat ] ) .
the main signatures of the emission reflected from cold neutral medium are well known
the fluorescent k@xmath0 line of iron at 6.4 kev , iron k - edge at 7.1 kev and a broad hump above @xmath1 kev ( basko , sunyaev & titarchuk 1974 , george & fabian 1991 ) .
the exact shape of these spectral features in the x - ray binaries depends on the ionization state of the reflecting medium ( @xcite ) and might be modified by the strong gravity effects and intrinsic motions in the reflector ( e.g. fabian et al . , 1989 ) .
the amplitude of the reflection signatures....
And you have already written the first three sentences of the full article: the results presented below are based on the publicly available data of cyg x1 , gx3394 and gs1354644 observations with the proportional counter array aboard the rossi x - ray timing explorer ( @xcite ) from 19961998 during the low ( hard ) spectral state of the sources . in total
our sample included @xmath4 observations of these sources .
the energy and power density spectra were averaged for each individual observation ..
Please generate the next two sentences of the article | the energy spectra were extracted from the `` standard mode 2 '' data and arf and rmf were constructed using standard rxte ftools v.4.2 tasks .
the `` vle '' and `` q6 '' models were used for the background calculation with the preference being given to the `` vle '' model when possible . a uniform systematic error of 0.5% was added quadratically to the statistical error in each energy channel . |
9,724 | Suppose that you have an abstract for a scientific paper: hierarchical mergers of galaxies can form binary black holes ( bbhs ) since many or most galaxies have central massive black holes ( bhs ) .
it is possible that some bbhs exist in active galactic nuclei ( agns ) .
we argue that each bh may be surrounded by an accretion disc with a different inclination angle to the line of sight ( due to different bh spin directions and the bardeen - petterson effect ) .
the observed line profile from a bbh system is a combination of the lines from the inner regions of the two discs , which is significantly affected by the inclination angles of the two discs .
the line profile associated with bbhs may have an unusual shape with double or more peaks as well as short - term variability , which can be distinguished from the line properties of some other possible models .
we suggest that with the improvement of resolution in x - ray astronomy , line profiles be a potential tool to probe the existence of massive bbhs in agns . the line profile associated with bbhs
may also provide a tool to investigate the dynamics in strong gravitation field ( e.g. providing evidence of the bardeen - petterson effect ) . .
And you have already written the first three sentences of the full article: much evidence indicates that massive black holes ( bhs ) reside in the centers of many or most galaxies ( e.g. @xcite ) .
mergers of galaxies are likely to form massive binary black holes ( bbhs ) .
theoretical estimation shows that the bbh lifetime is not much shorter than the hubble time and many bbhs should be still in the centers of galaxies ( @xcite ) ..
Please generate the next two sentences of the article | the existence of bbhs in the universe will not only provide a laboratory to test gravitation radiation theory and bh physics , but also probe of the hierarchical structure model of galaxy and large - scale structure formation . currently , there is no systematic and unambiguous method to identify bbhs .
bbhs stay at a separation in the range @xmath0 cm ( e.g. @xmath1 arcsec at 10mpc ) during the slowest evolution period ( @xcite ) , and thus it is hard to resolve a bbh two very close galactic nuclei in the image with current telescope resolution . |
9,725 | Suppose that you have an abstract for a scientific paper: we investigate the action of time dependent detunings upon the excitation inversion of a cooper pair box interacting with a nanomechanical resonator .
the method employs the jaynes - cummings model with damping , assuming different decay rates of the cooper pair box and various fixed and t - dependent detunings .
it is shown that while the presence of damping plus constant detunings destroy the collapse / revival effects , convenient choices of time dependent detunings allow one to reconstruct such events in a perfect way .
it is also shown that the mean excitation of the nanomechanical resonator is more robust against damping of the cooper pair box for convenient values of t - dependent detunings . .
And you have already written the first three sentences of the full article: a popular and exactly soluble model in quantum optics is the jaynes - cumming model ( jcm ) .
it describes the interaction of a two - level atom with a single - mode of the electromagnetic field @xcite . over the last two decades
various extensions of the ordinary jcm have been used in various directions , e.g. , as adapted to : ( i ) the study of interaction of a three - level atom with a two - mode squeezed vacuum @xcite ; ( ii ) the study of atom - field interaction in the presence of a cavity damping @xcite ; ( iii ) the same as in ( i ) , including an additional ( nonlinear ) kerr medium @xcite ; ( iv ) the two - level atoms inside a cavity acted upon by an external field control @xcite ; ( v ) study of the nonlinear dynamical evolution of a driven two - photon jaynes - cummings model @xcite ; ( vi ) the study of a generalized jaynes - cummings models , including dissipation 15,16,16a and multiphoton interactions @xcite ; etc . in all these cases , with interest either on the field or on atomic properties , the theoretical approach traditionally assumes the atom - field coupling as a constant parameter ..
Please generate the next two sentences of the article | comparatively , the number of works in the literature is very small when one considers such coupling and the atomic frequency as time dependent parameters @xcite , including time dependent amplitudes @xcite .
however , this scenario is also relevant ; for example , the state of two qubits ( qubits stand for quantum bits ) with a desired degree of entanglement can be generated via a time dependent atom - field coupling @xcite . |
9,726 | Suppose that you have an abstract for a scientific paper: `` symmetry '' was one of the most important methodological themes in 20th - century physics and is probably going to play no lesser role in physics of the 21st century .
as used today , there are a variety of interpretations of this term , which differ in meaning as well as their mathematical consequences .
symmetries of crystals , for example , generally express a different kind of invariance than gauge symmetries , though in specific situations the distinctions may become quite subtle .
i will review some of the various notions of `` symmetry '' and highlight some of their uses in specific examples taken from pauli s scientific vre .
this paper is based on a talk given at the conference _
wolfgang pauli s philosophical ideas and contemporary science _ , may 20.-25 .
2007 , at monte verita , ascona , switzerland
. 10000 .
And you have already written the first three sentences of the full article: in the introduction to pauli s collected scientific papers , the editors , ralph kronig and victor weisskopf , make the following statement : _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ it is always hard to look for a leading principle in the work of a great man , in particular if his work covers all fundamental problems of physics .
pauli s work has one....
Please generate the next two sentences of the article | the search for symmetry and general validity transcend the limits of physics in pauli s work ; it penetrated his thinking and striving throughout all phases of his life , in all fields of philosophy and psychology._(@xcite , vol.1 , p.viii ) _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ indeed , if i were asked to list those of pauli s scientific contributions... |
9,727 | Suppose that you have an abstract for a scientific paper: a langevin equation of heavy quarks in high - temperature quark - gluon plasma is derived .
the dynamics of heavy quark color is coupled with the phase space dynamics and causes a macroscopic superposition state of heavy quark momentum .
decoherence of the superposition state allows one to use a classical description .
the time scale of decoherence gives an appropriate discretization time scale @xmath0 for the classical langevin equation , where @xmath1 is heavy quark mass and @xmath2 is heavy quark momentum diffusion constant . .
And you have already written the first three sentences of the full article: the transport properties of quark - gluon plasma ( qgp ) have attracted a lot of interest since nearly perfect liquid behavior has been discovered in the relativistic heavy - ion collision experiments at the relativistic heavy ion collider ( rhic ) @xcite .
further investigations in the heavy - ion collisions at higher energy are ongoing at the large hadron collider ( lhc ) .
the discovery of nearly perfect liquid behavior seems to contradict the notion of weakly interacting qgp , and it rather suggests a strongly interacting nature of the qgp . indeed , the universal lower bound of the ratio of shear viscosity to entropy density @xmath3 is proposed in the strongly interacting quantum field theories based on the conjectured duality between the gauge theory and string theory , or the anti - de - sitter space and conformal field theory ( ads / cft ) correspondence @xcite ..
Please generate the next two sentences of the article | this is close to the value @xmath4 , which is phenomenologically extracted from the experimental data by hydrodynamic simulations for the heavy - ion collisions @xcite . in the heavy - ion collisions , not only the bulk collective dynamics but also hard probes , such as heavy quarks and jets ,
reveal independent aspects of the transport properties of the qgp . for example , medium modification of heavy quark momentum spectra offers an opportunity to study drag force of the qgp acting on a test particle with color @xcite . |
9,728 | Suppose that you have an abstract for a scientific paper: in energy harvesting communication systems , an exogenous recharge process supplies energy for the data transmission and arriving energy can be buffered in a battery before consumption .
transmission is interrupted if there is not sufficient energy .
we address communication with such random energy arrivals in an information - theoretic setting . based on the classical additive white gaussian noise ( awgn ) channel model , we study the coding problem with random energy arrivals at the transmitter . we show that the capacity of the awgn channel with stochastic energy arrivals is equal to the capacity with an average power constraint equal to the average recharge rate .
we provide two different capacity achieving schemes : _ save - and - transmit _ and _ best - effort - transmit_. next , we consider the case where energy arrivals have time - varying average in a larger time scale .
we derive the optimal offline power allocation for maximum average throughput and provide an algorithm that finds the optimal power allocation . .
And you have already written the first three sentences of the full article: in this paper , we analyze point - to - point communication of energy harvesting nodes from an information - theoretic perspective .
we focus on wireless networking applications where nodes ( e.g. , sensors nodes ) can harvest energy from nature through various different sources , such as solar cells , vibration absorption devices , water mills , thermoelectric generators , microbial fuel cells , etc . in such systems ,
energy that becomes available for data transmission can be modeled as an exogenous recharge process ..
Please generate the next two sentences of the article | therefore , unlike traditional battery - powered systems , in these systems , energy is not a deterministic quantity , but is a random process which varies stochastically in time at a scale on the order of symbol duration .
the transmission can be interrupted due to lack of energy in the battery . on the other hand , |
9,729 | Suppose that you have an abstract for a scientific paper: we review recent progress in the understanding of the spin structure of the nucleon . for the free nucleon
the issues addressed include the status of the bjorken and ellis - jaffe sum - rules and the role of the axial anomaly .
we outline recent work connecting the quark models familiar from hadron spectroscopy to the spin and flavour dependence of the parton distributions .
finally we review the current understanding of nuclear spin structure functions and particularly the extraction of the neutron spin structure function from deuteron data .
= 5.5truein = 8.5truein adp-94 - 21/t161 + invited paper at spin 94 + bloomington , september 1994 .
And you have already written the first three sentences of the full article: measurements of the spin - dependent structure function of the nucleon , @xmath0 , continue to generate enormous interest .
not only has the precision with which the ellis - jaffe sum - rule is known improved , but with the addition of neutron data from slac and smc the bjorken sum - rule has also been tested @xcite .
our aim is to provide a necessarily brief review of the situation with respect to the sum - rules ..
Please generate the next two sentences of the article | ( for those interested in more detail we suggest some recent reviews @xcite . )
we then argue that the emphasis in future should be much more on the shape and momentum dependence of @xmath0 . |
9,730 | Suppose that you have an abstract for a scientific paper: with the arrival of modern internet era , large public networks of various types have come to existence to benefit the society as a whole and several research areas such as sociology , economics and geography in particular . however , the societal and research benefits of these networks have also given rise to potentially significant privacy issues in the sense that malicious entities may violate the privacy of the users of such a network by analyzing the network and deliberately using such privacy violations for deleterious purposes .
such considerations have given rise to a new active research area that deals with the quantification of privacy of users in large networks and the corresponding investigation of computational complexity issues of computing such quantified privacy measures .
in this paper , we formalize three such privacy measures for large networks and provide non - trivial theoretical computational complexity results for computing these measures .
our results show the first two measures can be computed efficiently , whereas the third measure is provably hard to compute within a logarithmic approximation factor .
furthermore , we also provide computational complexity results for the case when the privacy requirement of the network is severely restricted , including an efficient logarithmic approximation . .
And you have already written the first three sentences of the full article: social networks have certainly become an important center of attention in our modern information society by transforming human relationships into a huge interchange of , very often , _ sensitive _ data .
there are many truly beneficial consequences when social network data are released for justified mining and analytical purposes .
for example , researchers in sociology , economics and geography , as well as vendors in service - oriented systems and internet advertisers can certainly benefit and improve their performances by a fair study of the social network data ..
Please generate the next two sentences of the article | but , such benefits are definitely _ not _ free of cost as dishonest individuals or organizations may compromise the _ privacy _ of its users while scrutinizing a public social network and may deliberately use such privacy violations for harmful or other unfair commercial purposes . a common way to handle this kind of unwelcome intrusion on the user s privacy
is to somehow _ anonymize _ the data by removing most potentially identifying attributes . |
9,731 | Suppose that you have an abstract for a scientific paper: we use data from the cosmic assembly near - infrared deep extragalactic legacy survey to study how the spatial variation in the stellar populations of galaxies relate to the formation of galaxies at @xmath0 .
we use the internal color dispersion ( icd ) , measured between the rest - frame uv and optical bands , which is sensitive to age ( and dust attenuation ) variations in stellar populations .
the icd shows a relation with the stellar masses and morphologies of the galaxies .
galaxies with the largest variation in their stellar populations as evidenced by high icd have disk - dominated morphologies ( with srsic indexes @xmath1 ) and stellar masses between @xmath2 .
there is a marked decrease in the icd as the stellar mass and/or the srsic index increases . by studying the relations between the icd and other galaxy properties including sizes , total colors , star - formation rate , and dust attenuation ,
we conclude that the largest variations in stellar populations occur in galaxies where the light from newly , high star - forming clumps contrasts older stellar disk populations .
this phase reaches a peak for galaxies only with a specific stellar mass range , @xmath2 , and prior to the formation of a substantial bulge / spheroid .
in contrast , galaxies at higher or lower stellar masses , and/or higher srsic index ( @xmath3 ) show reduced icd values , implying a greater homogeneity of their stellar populations .
this indicates that if a galaxy is to have both a quiescent bulge along with a star forming disk , typical of hubble sequence galaxies , this is most common for stellar masses @xmath4 and when the bulge component remains relatively small ( @xmath5 ) . .
And you have already written the first three sentences of the full article: in the local universe , galaxies separate into two broad classes @xcite : ( 1 ) large disk - dominated galaxies show ongoing star formation rates ( sfrs ) comparable to their past averages as evidenced by their overall blue colors , and frequent spiral arms , and ( 2 ) spheroidal , or bulge - dominated galaxies with current sfrs much less than their past averages .
however , especially in the more distant universe , there exists a third class of galaxies which exhibits a large amount of stellar population diversity and irregular morphologies ( e.g. , @xcite ) .
the mechanism by which a galaxy transitions from a uniformly blue , star forming galaxy ( with either disk - dominated or irregular morphologies ) into a bulge - dominated , quiescent galaxy remains an open question ..
Please generate the next two sentences of the article | many studies have added to a growing body of evidence that the irregular morphologies are due , at least in part , to heterogeneous ( clumpy ) star formation ( e.g. , @xcite )
. believed to be formed through gravitational instabilities in gas - rich disks ( e.g. , @xcite ) , these clumps typically contribute @xmath6 of the total galaxy light @xcite and most have bluer colors and elevated specific star formation rates ( ssfr ) compared to the surrounding regions @xcite . |
9,732 | Suppose that you have an abstract for a scientific paper: new x - ray observations with xmm - newton show a lack of spectral evidence for large amounts of cooling and condensing gas in the centers of galaxy clusters believed to harbour strong cooling flows . here , we explore these diagnostics of the temperature structure of cooling cores with xmm - spectroscopy .
we further find no evidence of intrinsic absorption in the center of the cooling flows of m87 and the perseus cluster .
to explain these findings we consider the heating of the core regions of clusters by jets from a central agn .
we find that the power of the agn jets as estimated by their interaction effects with the intracluster medium in several examples is more then sufficient to heat the cooling flows .
we explore which requirements such a heating model has to fulfill and find a very promising scenario of self - regulated bondi accretion of the central black hole . in summary
it is argued that most observational evidence points towards much lower mass deposition rates than previously inferred for cooling flow clusters .
# 1_#1 _ # 1_#1 _ = # 1 1.25 in .125 in .25 in .
And you have already written the first three sentences of the full article: x - ray imaging observations have shown that the x - ray emitting , hot gas in a large fraction of all galaxy clusters reaches high enough densities in the cluster centers that the cooling time of the gas falls below the hubble time , and gas may cool and condense in the absence of a suitable fine - tuned heating source ( e.g. silk 1976 , fabian & nulsen 1977 ) . from the detailed analysis of surface brightness profiles of x - ray images of clusters obtained with the _ einstein _ , _ exosat _ , and _ rosat _ observatories , the detailed , self - consistent scenario of inhomogeneous , comoving cooling flows emerged ( e.g. fabian et al .
1984 , nulsen 1986 , thomas , fabian , & nulsen 1987 , fabian 1994 ) .
the main assumptions on which the cooling flow model is based and some important implications are : ( i ) each radial zone in the cooling flow region comprises different plasma phases covering a wide range of temperatures ..
Please generate the next two sentences of the article | the consequence of this temperature distribution is that gas will cool to low temperature and condense over a wide range of radii .
( ii ) the gas features an inflow in which all phases with different temperature move with the same flow speed . |
9,733 | Suppose that you have an abstract for a scientific paper: in this paper we show that a lattice balanced polygon of odd area can not be cut into an odd number of triangles of equal areas .
first result of this type was obtained by paul monsky in 1970 .
he proved that a square can not be cut into an odd number of triangles of equal areas . in 2000
sherman stein conjectured that the same holds for any balanced polygon .
we also show connections between the equidissection problem and tropical geometry . .
And you have already written the first three sentences of the full article: [ p. monsky , 1970 ] a square can not be cut illustrates this . ] into an odd number of triangles of equal areas .
the only known proof of this theorem was published by monsky in 1970 @xcite . the proof is based on two key ideas : the sperner s lemma and the coloring of the plane in three colors based on a 2adic valuation .
after that , several generalizations of monsky s results appear ..
Please generate the next two sentences of the article | the first generalization was conjectured by stein and proved by monsky in 1990 @xcite .
it claims that a centrally symmetric polygon can not be cut into an odd number of triangles of equal areas . |
9,734 | Suppose that you have an abstract for a scientific paper: the long - term distributions of trajectories of a flow are described by invariant densities , i.e. fixed points of an associated transfer operator . in addition
, global slowly mixing structures , such as almost - invariant sets , which partition phase space into regions that are almost dynamically disconnected , can also be identified by certain eigenfunctions of this operator .
indeed , these structures are often hard to obtain by brute - force trajectory - based analyses . in a wide variety of applications ,
transfer operators have proven to be very efficient tools for an analysis of the global behavior of a dynamical system .
the computationally most expensive step in the construction of an approximate transfer operator is the numerical integration of many short term trajectories . in this paper , we propose to directly work with the _ infinitesimal generator _ instead of the operator , completely avoiding trajectory integration .
we propose two different discretization schemes ; a cell based discretization and a spectral collocation approach .
convergence can be shown in certain circumstances .
we demonstrate numerically that our approach is much more efficient than the operator approach , sometimes by several orders of magnitude . .
And you have already written the first three sentences of the full article: analysis of the long - term behavior of flows can be broadly classified into geometric methods and statistical methods .
geometrical methods include the determination of fixed points , periodic orbits , and invariant manifolds .
invariant manifolds of fixed points or periodic orbits act as barriers to transport as trajectories may not cross the manifolds transversally ..
Please generate the next two sentences of the article | statistical methods include determining the distribution of points in very long trajectories of a very large set of initial points ( i.e. a physical invariant measure @xcite , often possessing an invariant density ) and the identification of meta - stable or almost - invariant sets @xcite .
almost - invariant sets partition the phase space into almost dynamically disconnected regions and are important for revealing global dynamical structures that are often invisible to an analysis of trajectories . |
9,735 | Suppose that you have an abstract for a scientific paper: we revisit a one - step control problem over an adversarial packet - dropping link .
the link is modeled as a set of binary channels controlled by a strategic jammer whose intention is to wage a ` denial of service ' attack on the plant by choosing a most damaging channel - switching strategy .
the paper introduces a class of zero - sum games between the jammer and controller as a scenario for such attack , and derives necessary and sufficient conditions for these games to have a nontrivial saddle - point equilibrium . at this equilibrium ,
the jammer s optimal policy is to randomize in a region of the plant s state space , thus requiring the controller to undertake a nontrivial response which is different from what one would expect in a standard stochastic control problem over a packet dropping channel . .
And you have already written the first three sentences of the full article: the topic of control over a communication channel has been extensively studied in the past decade , with issues such as the minimum data rate for stabilization @xcite and optimal quadratic closed - loop performance @xcite being the main focus .
other issues of interest concern effects of channel - induced packet drops and/or time - varying delays on closed - loop performance . the majority of papers concerned with control over networks regards the mechanism of information loss in the network as probabilistic but not strategic . in contrast , in the problem of control over an _ adversarial _ channel , the communication link is controlled by a rogue jammer whose intention is to mount a cyber attack on the system by actively jamming the communication link .
its objectives are to impose on the controller a control law which can not be expected under regular operating conditions in a packet - dropping network.
Please generate the next two sentences of the article | . if the controller is unaware of the jammer s actions and continues to follow a control policy designed for a regular network , the system performance is likely to be inferior .
it is this situation that is considered as a scenario of a successful cyber attack by the jammer . a natural way to describe |
9,736 | Suppose that you have an abstract for a scientific paper: using the collider detector at fermilab , cdf , we have measured exclusive @xmath0 production at @xmath1 = 900 gev and 1960 gev .
the @xmath0-pair is central , @xmath2 1.0 , and there are no other particles detected in @xmath3 .
we discuss the mass spectrum , showing @xmath4 and @xmath5 resonances , @xmath6-dependence , @xmath7-dependence , and angular distributions . .
And you have already written the first three sentences of the full article: in regge phenomenology , high mass single diffraction implies a non - zero triple - pomeron coupling , which in turn implies , through the optical theorem , double pomeron exchange , d@xmath8e , : @xmath9 . here
@xmath10 means a proton or antiproton , the final state protons may be quasi - elastic or they may dissociate ( @xmath11 ) , and @xmath12 represents a large rapidity gap @xmath13 with no hadrons .
see ref.@xcite for a review . by .
Please generate the next two sentences of the article | exclusive " we mean that the central state @xmath14 is simple and fully measured . at low masses , in the resonance region @xmath15 3 gev , d@xmath8e is non - perturbative and qcd ( or qcd - inspired ) calculations are challenging ; there are new efforts by the durham @xcite and cracow @xcite groups .
the quantum numbers of @xmath14 are restricted to be mostly @xmath16 , so @xmath6-channel resonances @xmath17 and @xmath18 are allowed . |
9,737 | Suppose that you have an abstract for a scientific paper: in @xcite , the first author constructed the first known examples of exotic minimal symplectic @xmath0 and minimal symplectic @xmath1-manifold that is homeomorphic but not diffeomorphic to @xmath2 .
the construction in @xcite uses y. matsumoto s genus two lefschetz fibrations on @xmath3 over @xmath4 along with the fake symplectic @xmath5 construction given in @xcite .
the main goal in this paper is to generalize the construction in @xcite using the higher genus versions of matsumoto s fibration constructed by mustafa korkmaz and yusuf gurtas on @xmath6 for any @xmath7 and @xmath8 , and @xmath9 and @xmath10 , respectively . using our building blocks
, we also construct symplectic @xmath1-manifolds with the free group of rank @xmath11 and various other finitely generated groups as the fundamental group . .
And you have already written the first three sentences of the full article: the main goal of this paper is to exhibit a new family of simply connected minimal symplectic and infinitely many non - symplectic @xmath1-manifolds that is homeomorphic but not diffemorphic to @xmath12 for any @xmath13 and @xmath9 .
our construction is a generalization of the first author s work in @xcite , where he used yukio matsumoto s genus two lefschetz fibrations on @xmath3 over @xmath4 , arising from the elliptic involution of the genus two surface with two fixed points , along with the fake symplectic @xmath5 construction in @xcite obtained via knot surgery along the fibered knots . in the aforementioned paper @xcite , using the symplectic connected sum along the genus two surfaces , the first author has constructed the first known exotic minimal symplectic @xmath0 and minimal symplectic @xmath1-manifold that is homeomorphic but not diffeomorphic to @xmath2
. a straightforward generalization of these symplectic examples to an exotic @xmath14 ( for @xmath15 ) , using matsumoto s genus two fibration , can be found in @xcite , where the geography problem for simply connected minimal symplectic @xmath1-manifolds with signature less than equal @xmath16 studied in details . considering that mustafa kormaz s and yusuf gurtas higher genus lefschetz fibrations on @xmath6 , arising from the involution of the genus @xmath17 surface , are the generalizations of matsumoto s genus two fibration , it was a natural question whether the similar construction can be carried out using these higher genus lefschetz fibrations ..
Please generate the next two sentences of the article | the fundamental group of these lefschetz fibrations are not abelian if @xmath7 and the relations in the fundamental group coming from the vanishing cycles are far more complicated , thus the fundamental group computations become more difficult and delicate than in @xcite . in this article , by carefully analysing the fundamental group ,
we overcome these difficulties and prove the following theorem : [ thm : main ] let @xmath18 be @xmath12 for any @xmath13 and @xmath9 . there exists a new family of smooth closed simply - connected minimal symplectic @xmath1-manifold and an infinite family of non - symplectic @xmath1-manifolds that are homeomorphic but not diffeomorphic to @xmath18 . |
9,738 | Suppose that you have an abstract for a scientific paper: it is currently possible to fabricate crystalline silicon solar cells with the absorber thickness ranging from a few hundreds of micrometers ( conventional wafer - based cells ) to devices as thin as @xmath0 . in this work ,
we use a model single - junction solar cell to calculate the limits of energy conversion efficiency and estimate the optimal absorber thickness .
the limiting efficiency for cells in the thickness range between 40 and @xmath1 is very similar and close to 29% . in this regard , we argue that decreasing the thickness below around @xmath2 is counter - productive , as it significantly reduces the maximum achievable efficiency , even when optimal light trapping is implemented .
we analyse the roles of incomplete light trapping and extrinsic ( bulk and surface ) recombination mechanisms . for a reasonably high material quality ,
consistent with present - day fabrication techniques , the optimal thickness is always higher than a few tens of micrometers .
we identify incomplete light trapping and parasitic losses as a major roadblock in improving the efficiency upon the current record of 25.6% for silicon solar cells . finally , considering the main parameters that impact solar cell performance , we quantify the constraints and requirements for achieving a specified energy conversion efficiency , which is important for a proper design strategy of high efficiency silicon solar cells . .
And you have already written the first three sentences of the full article: in this work we focus on the efficiency limits of crystalline silicon ( c - si ) solar cells . in this regard , we consider both ideal devices ( perfect material and interfaces ) , as well as more realistic conditions , including defect - related recombinations , parasitic losses , and non - optimal light management .
it is currently possible to fabricate c - si solar cells with absorber thickness values that differ by two orders of magnitude . on the one end of the thickness range
there are conventional wafer - based c - si solar cells with the absorber thickness of the order of a few hundreds of micrometers @xcite ..
Please generate the next two sentences of the article | epitaxial growth allows fabricating solar cells with the thickness of a few tens of micrometers @xcite .
finally , epitaxy - free fabrication@xcite makes possible fabricating c - si solar cells with the absorbing layer as thin as @xmath0 . for a proper design strategy , |
9,739 | Suppose that you have an abstract for a scientific paper: we use the number density of peaks in the smoothed cosmological density field taken from the 2df galaxy redshift survey to constrain parameters related to the power spectrum of mass fluctuations , @xmath0 ( the spectral index ) , d@xmath1/dln@xmath2 ( rolling in the spectral index ) , and the neutrino mass , @xmath3 . in a companion paper
we use n - body simulations to study how the peak density responds to changes in the power spectrum , the presence of redshift distortions and the relationship between galaxies and dark matter halos . in the present paper
we make measurements of the peak density from 2df galaxy redshift survey data , for a range of smoothing filter scales from @xmath4 .
we use these measurements to constrain the cosmological parameters , finding @xmath5 , @xmath6ev , @xmath7n@xmath8k@xmath9 , at the 68 % confidence level , where @xmath3 is the total mass of three massive neutrinos . at 95% confidence
we find @xmath10 ev .
these measurements represent an alternative way to constrain cosmological parameters to the usual direct fits to the galaxy power spectrum , and are expected to be relatively insensitive to non - linear clustering evolution and galaxy biasing .
[ firstpage ] .
And you have already written the first three sentences of the full article: the space density of peaks in a cosmological density field smoothed with a filter is sensitive to the shape of the linear power spectrum of mass fluctuations , even for filter sizes where the fluctuations are in the non - linear regime ( croft & gaztaaga 1998 ) . in de & croft ( 2007 ) ,
hereafter paper i we explored the sensitivity of the peak density to parameters related to the initial power spectrum , as well as redshift distortions and variations in the galaxy halo occupation distribution ( e.g. , berlind & weinberg 2002 ) . the theory of peaks in a gaussian density field was set out in detail by bardeen ( 1986 , hereafter bbks ) .
the relationship between the peak density and power spectrum in bbks can be used to explore such parameters as the spectral index and its dependence on scale ( kosowsky and turner , 1991 ) along with the neutrino mass . in this paper.
Please generate the next two sentences of the article | we use data from the 2df galaxy redshift survey ( hereafter 2dfgrs , colless 2001 ) , to constrain cosmological parameters using the peak density . in a recent analysis of the 2dfgrs final data set cole ( 2005 ) employed a direct fourier method to compute the power spectrum .
these authors put constraints on several parameters using the directly measured power spectrum shape . |
9,740 | Suppose that you have an abstract for a scientific paper: we introduce a scheme to perform quantum - information processing that is based on a hybrid spin - photon qubit encoding .
the proposed qubits consist of spin - ensembles coherently coupled to microwave photons in coplanar waveguide resonators .
the quantum gates are performed solely by shifting the resonance frequencies of the resonators on a ns timescale .
an additional cavity containing a cooper - pair box is exploited as an auxiliary degree of freedom to implement two - qubit gates .
the generality of the scheme allows its potential implementation with a wide class of spin systems .
3 cm a classical computer is made of a variety of physical components specialized for different tasks . in the same way
, a quantum computer will probably be a hybrid device exploiting the best characteristics of distinct physical systems . in this spirit
, much work has recently been done to achieve strong coupling of high - quality factor coplanar - waveguide resonators with superconducting qubits , such as cooper - pair boxes ( cpbs ) [ ] and transmons [ ] and/or spin ensembles ( ses ) [ ] .
superconducting qubits coupled to a microwave cavity field were proposed for quantum information processing ( qip ) [ ] , using classical fields [ ] or external voltages [ ] as a manipulation tool . during the last years several theoretical works have considered the possibility of joining the fast processing of superconducting qubits to the long coherence times of ses [ ] , which can be naturally exploited as quantum memories .
cavity photons can be used as a bus to transfer the quantum state from cpbs to spin ensembles , and to couple distant cpb qubits , leading to an effective interaction necessary to perform two - qubit gates [ ] .
recently , it was theoretically shown that a minimal architecture solely based on ses can be exploited for full qip [ ] , by employing a measurement - based scheme in which photons are still used as a quantum bus .
+ here we introduce a qualitatively different approach....
And you have already written the first three sentences of the full article: the scheme for quantum information processing described in the main text exploits a cooper - pair box ( cpb ) [ ] , whose hamiltonian can be written in the basis of the charge states @xmath124 ( with @xmath125 ) [ ] as @xmath126 where @xmath127 is the josephson energy , @xmath128 is the charging energy and @xmath129 is the dimensionless gate charge .
the numerical diagonalization of ( [ cpb2 ] ) with @xmath130 , @xmath131 and @xmath132 [ ] yields a highly anharmonic spectrum .
hence , we can safely truncate the hilbert space of the cpb to the lowest three levels shown in the central part of fig ..
Please generate the next two sentences of the article | 2(b ) of the main text . in this regime coherence times of the cpb
are considerably longer than the cz gating time [ ] and the spectrum is sufficiently anharmonic to obtain high fidelities in our simulations . |
9,741 | Suppose that you have an abstract for a scientific paper: a luminous optical transient ( ot ) that appeared in ngc 300 in early 2008 had a maximum brightness , @xmath0 to @xmath1 , intermediate between classical novae and supernovae .
we present ground - based photometric and spectroscopic monitoring and adaptive - optics imaging of the ot , as well as pre- and post - outburst space - based imaging with and _ spitzer_. the optical spectrum at maximum showed an f - type supergiant photosphere with superposed emission lines of hydrogen , , and [ ] , similar to the spectra of low - luminosity type iin `` supernova impostors '' like sn 2008s , as well as cool hypergiants like irc + 10420 .
the emission lines have a complex , double structure , indicating a bipolar outflow with velocities of @xmath2@xmath3 . the luminous energy released in the eruption was @xmath2@xmath4 ergs , most of it emitted in the first 2 months . by registering new images with deep archival frames , we have precisely located the ot site , and find no detectable optical progenitor brighter than broad - band @xmath5 magnitude 28.5 .
however , archival _ spitzer _ images reveal a bright , non - variable mid - ir pre - outburst source .
we conclude that the ngc 300 ot was a heavily dust - enshrouded luminous star , of @xmath210@xmath6 , which experienced an eruption that cleared the surrounding dust and initiated a bipolar wind .
the progenitor was likely an oh / ir source which had begun to evolve on a blue loop toward higher temperatures , but the precise cause of the outburst remains uncertain . .
And you have already written the first three sentences of the full article: in recent years , eruptive objects with maximum luminosities intermediate between those of classical novae ( cne ) and supernovae ( sne ) have been discovered in increasing numbers , as surveys for galactic and extragalactic transients are made with greater depth and sky coverage by professional and amateur astronomers .
the term `` supernova impostors '' was introduced by van dyk et al.(2000 ) following the outburst of sn 1997bs .
sn 1997bs was classified as a sn iin event , `` n '' denoting narrow emission lines during outburst , in contrast to the high ejection velocities of typical sne ..
Please generate the next two sentences of the article | however , it reached an absolute magnitude at maximum of only @xmath7 , more than 3 mag fainter than a typical core - collapse sn .
van dyk et al . argued that sn 1997bs was instead a `` superoutburst '' of a massive luminous blue variable ( lbv ) , analogous to those experienced by the galactic objects p cygni and @xmath8 carinae ( see humphreys , davidson , & smith 1999 ) . |
9,742 | Suppose that you have an abstract for a scientific paper: in this paper , we study representation homology of topological spaces , that is a natural homological extension of representation varieties of fundamental groups . we give an elementary construction of representation homology in terms of classical ( abelian ) homological algebra .
our construction is parallel to the loday - pirashvili construction of higher hochschild homology @xcite ; in fact , we establish a direct geometric relation between the two theories by proving that the representation homology of the ( reduced ) suspension of a ( pointed connected ) space is isomorphic to its higher hochschild homology .
we also construct some natural maps and spectral sequences relating representation homology to other standard homology theories associated with spaces ( such as pontryagin algebras , @xmath0-equivariant homology of the free loop space and stable homology of automorphism groups of f.g .
free groups ) .
we compute representation homology explicitly ( in terms of known invariants ) in a number of interesting cases , including spheres , suspensions , complex projective spaces , riemann surfaces and some 3-dimensional manifolds ( such as link complements in @xmath1 and the lens spaces @xmath2 ) .
one of our main results , which we call the comparison theorem , expresses the representation homology of a simply - connected topological space of finite rational type in terms of its quillen and sullivan models . .
And you have already written the first three sentences of the full article: let @xmath3 be a finite - dimensional affine algebraic group defined over a field @xmath4 of characteristic zero
. for any ( discrete ) group @xmath5 , the set of all representations of @xmath5 in @xmath3 has a natural structure of an affine @xmath4-scheme called the _ representation scheme _ @xmath6 .
the representation schemes and associated representation varieties play an important role in many areas of mathematics , most notably in representation theory and low - dimensional topology . in representation theory , the fundamental problem is to understand the structure of representations of @xmath5 in @xmath3 ..
Please generate the next two sentences of the article | one can approach this problem geometrically by studying the natural ( adjoint ) action of the group @xmath3 on the variety @xmath6 .
when @xmath7 is algebraically closed and @xmath5 is finitely generated , the equivariant geometry of @xmath8 is closely related to the representation theory of @xmath5 : the equivalence classes of representations of @xmath5 in @xmath3 are in bijection with the @xmath3-orbits in @xmath8 , and the geometry of @xmath3-orbits determines the algebraic structure of representations . this relation has been extensively studied since the late 70s , and the representation varieties have become a standard tool in representation theory of groups ( see , for example , @xcite ) . in topology , |
9,743 | Suppose that you have an abstract for a scientific paper: the next generation health study investigates the dating violence of adolescents using a survey questionnaire .
each student is asked to affirm or deny multiple instances of violence in his / her dating relationship .
there is , however , evidence suggesting that students not in a relationship responded to the survey , resulting in excessive zeros in the responses .
this paper proposes likelihood - based and estimating equation approaches to analyze the zero - inflated clustered binary response data .
we adopt a mixed model method to account for the cluster effect , and the model parameters are estimated using a maximum - likelihood ( ml ) approach that requires a gaussian hermite quadrature ( ghq ) approximation for implementation .
since an incorrect assumption on the random effects distribution may bias the results , we construct generalized estimating equations ( gee ) that do not require the correct specification of within - cluster correlation . in a series of simulation studies ,
we examine the performance of ml and gee methods in terms of their bias , efficiency and robustness .
we illustrate the importance of properly accounting for this zero inflation by reanalyzing the next data where this issue has previously been ignored . , , .
And you have already written the first three sentences of the full article: in public health studies , clustered or longitudinal binary responses may be collected on a group of individuals where only a subset of these individuals are susceptible to having a positive response .
for example , questionnaires may ask teenagers who are dating to answer a series of questions about dating violence . as in the next generation health study , a larger proportion of all zero responses are observed than would occur by chance ; presumably many individuals who are not dating filled in all zeros on the questionnaire ( also known as `` structural zeros '' ) .
while there may be alternative reasons for structural zeros , for example , participants giving socially desirable responses , we believe this accounts for only a small fraction of zero inflation ..
Please generate the next two sentences of the article | interest is in making inference about the correlated binary responses for those who are susceptible ( i.e. , inference about dating violence among individuals who were dating ) .
there is an extensive literature on zero - inflated poisson and binomial models [ @xcite ; @xcite ] that provide early references , along with more recent work on zero - inflated ordinal data [ @xcite ] and zero - inflated sum score data with randomized responses [ @xcite ] . |
9,744 | Suppose that you have an abstract for a scientific paper: in the first part of this series of two papers , we proposed a theoretical formalism that enables one to model and categorize heterogeneous materials ( media ) via two - point correlation functions @xmath0 and introduced an efficient heterogeneous - medium ( re)construction algorithm called the `` lattice - point '' algorithm . here
we discuss the algorithmic details of the lattice - point procedure and an algorithm modification using surface optimization to further speed up the ( re)construction process .
the importance of the error tolerance , which indicates to what accuracy the media are ( re)constructed , is also emphasized and discussed .
we apply the algorithm to generate three - dimensional digitized realizations of a fontainebleau sandstone and a boron carbide / aluminum composite from the two - dimensional tomographic images of their slices through the materials . to ascertain whether the information contained in @xmath0 is sufficient to capture the salient structural features , we compute the two - point cluster functions of the media , which are superior signatures of the microstructure because they incorporate topological connectedness information .
we also study the reconstruction of a binary laser - speckle pattern in two dimensions , in which the algorithm fails to reproduce the pattern accurately .
we conclude that in general reconstructions using @xmath0 only work well for heterogeneous materials with single - scale structures
. however , two - point information via @xmath0 is not sufficient to accurately model multi - scale random media .
moreover , we construct realizations of hypothetical materials with desired structural characteristics obtained by manipulating their two - point correlation functions . .
And you have already written the first three sentences of the full article: random heterogeneous multiphase materials or media are ubiquitous .
examples include composites , porous media , biological materials as well as cosmological structures , and their macroscopic properties are of great interest @xcite . in the first part of this series of two papers @xcite ( henceforth referred to as paper i ) , we proposed a theoretical formalism to model and categorize heterogeneous materials via two - point correlation functions @xmath1 , which can be interpreted as the probability of finding two points separated by the the dsiplacement vector @xmath2 in one of the phases @xcite .
in particular , we introduced the idea of the two - point correlation function space and its basis functions ..
Please generate the next two sentences of the article | in general , @xmath0 of a medium can be expressed by a map @xmath3 on the associated basis functions , which is composed of convex - combination and product operations .
we also suggested a set of basis functions by examining certain known realizable analytical two - point correlation functions . |
9,745 | Suppose that you have an abstract for a scientific paper: we explore whether protoplanetary disks with self - shadowing from puffed up inner rims exhibit observable features in scattered light images .
we use both self - consistent hydrostatic equilibrium calculations and parameterized models to produce the vertically puffed up inner rims .
we find that , in general , the transition between the shadowed and flared regions occurs in a smooth manner over a broad radius range , and no sudden jump exists at the outer edge of the shadow in either the disk temperature or density structures . as a result ,
a puffed up rim can not create sharp ring / arc / spiral - arm - like features in the outer disk as have been detected in recent direct nir imaging of disks . on the other hand ,
if the puffed up rim has a sharp edge in the vertical direction , the shadowing effect can produce a distinct 3-stage broken power law in the radial intensity profile of the scattered light , with 2 steep surface brightness radial profiles in the inner and outer disk joined by a shallow transition region around the shadow edge .
these types of scattered light profiles may have already been observed , such as in the recent subaru direct imaging of the tw hydrae system . .
And you have already written the first three sentences of the full article: flattened , rotating circumstellar disks reprocess light from newly born stars in t tauri and herbig ae / be systems @xcite .
disks can modify the spectral energy distribution ( sed ) of the systems , and reveal themselves in resolved images at various wavelengths @xcite . in a disk ,
dust grains only exist outwards the sublimation radius @xmath0 , where dust reach sublimation temperature @xmath1 , leaving a dust - free hole at the center ..
Please generate the next two sentences of the article | protoplanetary disks are usually optically thick to stellar radiation ( with exceptions such as transitional disks , @xcite ) . as a result ,
most part of the disk receives direct starlight only at the surface , under a small grazing angle determined by the shape of the surface @xcite . on the other hand , |
9,746 | Suppose that you have an abstract for a scientific paper: detectability of failures of linear programming ( lp ) decoding and its potential for improvement by adding new constraints motivate the use of an adaptive approach in selecting the constraints for the lp problem . in this paper
, we make a first step in studying this method , and show that it can significantly reduce the complexity of the problem , which was originally exponential in the maximum check - node degree .
we further show that adaptively adding new constraints , e.g. by combining parity checks , can provide large gains in the performance . .
And you have already written the first three sentences of the full article: linear programming ( lp ) decoding , as an approximation to maximum - likelihood ( ml ) decoding , was proposed by feldman _ et al .
many observations suggest similarities between the performance of lp and iterative message - passing methods , e.g. in @xcite .
for example , we know that the existence of low - weight pseudo - codewords degrades the performance of both methods ( @xcite , @xcite ) . therefore , it is reasonable to make use of the simpler geometrical structure of lp decoding to make predictions on the performance of message - passing algorithms . on the other hand , there are differences which prevent us from making an explicit connection between these two approaches . for instance , given an ldpc code , adding additional parity checks that are satisfied by all the codewords can only improve lp decoding , while with message - passing algorithms , these parity checks may have a negative effect by introducing short cycles in the tanner graph ..
Please generate the next two sentences of the article | this property of lp decoding allows improvements by tightening the relaxation .
another characteristic of lp decoding ( the _ ml certificate property _ ) is that its failure to find the ml codeword is detectable . |
9,747 | Suppose that you have an abstract for a scientific paper: early observations of t tauri stars suggested that stars with evidence of circumstellar accretion disks rotated slower than stars without such evidence , but more recent results are not as clear . near - ir circumstellar disk indicators , though the most widely available , are subject to uncertainties that can result from inner disk holes and/or the system inclination .
mid - infrared observations are less sensitive to such effects , but until now , these observations have been difficult to obtain .
the spitzer space telescope now easily enables mid - infrared measurements of large samples of pms stars covering a broad mass range in nearby star - forming regions .
megeath and collaborators surveyed the orion molecular clouds ( @xmath01 myr ) with the irac instrument ( 3.6 , 4.5 , 5.8 , 8 @xmath1 ) as part of a joint irac and mips gto program .
we examine the relationship between rotation and spitzer mid - ir fluxes for @xmath0900 stars in orion for stars between 3 and 0.1 m@xmath2 .
we find in these spitzer data the clearest indication to date that stars with longer periods are more likely than those with short periods to have ir excesses suggestive of disks . .
And you have already written the first three sentences of the full article: the smallest molecular cores observed to date have at least @xmath06 orders of magnitude greater angular momentum per unit mass than the sun , suggesting that they would eventually greatly exceed the breakup velocity if no angular momentum was lost during the evolutionary process .
it is widely believed that most if not all low - mass stars form with circumstellar accretion disks ; accreting solar - like pre - main sequence ( pms ) stars have rotational velocities 1/5th to 1/10th of breakup speeds despite the angular momentum transported to the star via accretion from its circumstellar disk .
these fundamental observations lead to the conclusion that an angular momentum regulation mechanism must be at work during the accretion phase ..
Please generate the next two sentences of the article | stellar winds alone as conventionally invoked can not explain such angular momentum loss unless they operate completely differently than expected ( see , e.g. , sills et al .
2000 and references therein ) ; these young solar - like pms stars are completely convective , so winds must slow the rotation of the whole star ( not just the outer layers ) , and the timescale for winds to significantly slow a star s rotation is longer than the evolutionary timescales involved here . |
9,748 | Suppose that you have an abstract for a scientific paper: we present a time - resolved spectrophotometric study of the optical variability in the quiescent soft x - ray transient a062000 . superimposed on the double - humped continuum lightcurve
are the well known flare events which last tens of minutes
. some of the flare events that appear in the continuum lightcurve are also present in the emission line lightcurves . from the balmer line flux and variations , we find that the persistent emission is optically thin . during the flare event at phase 1.15 the balmer decrement dropped suggesting either a significant increase in temperature or that the flares are more optically thick than the continuum .
the data suggests that there are two hi emitting regions , the accretion disc and the accretion stream / disc region , with different balmer decrements .
the orbital modulation of h@xmath0 with the continuum suggests that the steeper decrement is most likely associated with the stream / disc impact region . by isolating the flare s spectrum
we find that it has a frequency power - law index of [email protected] ( 90 percent confidence ) .
the flare spectrum can also be described by an optically thin gas with a temperature in the range 1000014000k that covers 0.050.08 percent ( 90 percent confidence ) of the accretion disc s surface . given these parameters ,
the possibility that the flares arise from the bright - spot can not be ruled out .
we construct doppler images of the h@xmath0 and h@xmath2 emission lines .
apart from showing enhanced blurred emission at the region where the stream impacts the accretion disc , the maps also show significant extended structure from the opposite side of the disc .
the trailed spectra show characteristic s - wave features that can be interpreted in the context of an eccentric accretion disc .
accretion , accretion discs binaries : close stars : individual : a062000 .
And you have already written the first three sentences of the full article: soft x - ray transients ( sxts ) are a subset of low - mass x - ray binaries ( lmxb ) that display episodic , dramatic x - ray and optical outbursts , which usually last for several months . in the interim
the sxts are in a state of quiescence during which the optical emission is dominated by the luminosity of the faint companion star @xcite . in quiescence the optical lightcurves exhibit the classical double - humped ellipsoidal modulation , which is due to the differing aspects that the tidally distorted secondary star presents to the observer throughout its orbit ( e.g. see @xcite ; @xcite ; @xcite and @xcite ) .
the lmxb sxt prototype , a062000 ( = v616mon ) was discovered in 1975 by the ariel-5 satellite @xcite during an x - ray outburst whose peak flux made it the brightest nonsolar source ever seen ..
Please generate the next two sentences of the article | the optical counterpart was subsequently identified @xcite and after the system had faded back to its quiescent level , a062000 was found to be a 7.8hr binary system containing a k - type secondary star and a non - stellar continuum source attributed to an accretion disc ( @xcite ; @xcite ) .
a radial velocity study led to the discovery of the first black hole primary in an x - ray transient @xcite . |
9,749 | Suppose that you have an abstract for a scientific paper: we consider the resonant energy transfer from a two - dimensional wannier exciton ( donor ) to a frenkel exciton of a molecular crystal overlayer ( acceptor ) when the active medias are separated by a metallic layer , possibly an electrode .
we characterize the effect of the surface plasmon on this process . using realistic values of material parameters
, we show that it is possible to change the transfer rate within typically a factor of 5 ( up to 44 according to geometrical configuration ) .
we then take into account the quenching of the organic luminescence due to the proximity with the metal .
this latter is significant and affect negatively the total internal efficiency that we discuss for different geometries . .
And you have already written the first three sentences of the full article: semiconductor leds and their counterpart solar cells are expected to play a major role in general lightning and renewable energy production .
the development of organic light emitting diodes ( oled ) has proven to be successful and they are on the market , notwithstanding the disadvantages of a poor carrier injection and transport properties compared to inorganic semiconductors . an idea to further improve such devices
is the use of an hybrid system that would combine the best properties of both materials together and potentially open new possibilities for optoelectronic devices@xcite . in the strong coupling regime ,.
Please generate the next two sentences of the article | novel hybrid quasiparticles are formed , with properties diverse from those of the individual excitons leading to new uses in particular those requiring large nonlinearities as for optical switching . in the weak coupling regime ,
in which wannier and frenkel excitons maintain their individuality , a suitable use of each component would also bring new features@xcite and could overcome the drawback presented earlier . |
9,750 | Suppose that you have an abstract for a scientific paper: we study the dynamical stability of the macroscopic quantum oscillations characterizing a system of three coupled bose - einstein condensates arranged into an open - chain geometry .
the boson interaction , the hopping amplitude and the central - well relative depth are regarded as adjustable parameters . after deriving the _ stability diagrams _ of the system , we identify three mechanisms to realize the transition from an unstable to stable behavior and analyze specific configurations that , by suitably tuning the model parameters , give rise to macroscopic effects which are expected to be accessible to experimental observation . also , we pinpoint a system regime that realizes a josephson - junction - like effect . in this regime
the system configuration do not depend on the model interaction parameters , and the population oscillation amplitude is related to the condensate - phase difference .
this fact makes possible estimating the latter quantity , since the measure of the oscillating amplitudes is experimentally accessible . .
And you have already written the first three sentences of the full article: since the first observation of bose - einstein condensates ( becs ) in dilute weakly interacting gases of bosons in 1995 , great efforts both experimental and theoretical have been addressed on this subject . thus nowadays ,
thanks to the impressive progress of experimental techniques , becs represent a source of inspiration for new challenging problems in quantum physics . a notable aspect inherent in the dynamics of coupled becs
is that the nonlinear character of their equations of motion entails a particularly rich phenomenology where nonlinear effects including chaos can be studied in a quantum environment . among the latter , in recent experiments.
Please generate the next two sentences of the article | have been observed phenomena such as super - fluidity @xcite , josephson tunneling @xcite and atom optics @xcite .
if the recent past has been prolific of experiments on becs arranged into arrays with huge number ( of the order of several hundreds ) of condensates , at the present , the experiments on chains with a few interacting becs ( of the order of several unities ) has received a limited attention @xcite-@xcite despite the increasing amount of theoretical work devoted to such systems . over the last few years , |
9,751 | Suppose that you have an abstract for a scientific paper: the usual theoretical treatments of the near - threshold @xmath0 reaction are based on various phenomenological lagrangians . in this work
we examine the relationship between these approaches and a systematic chiral perturbation method .
our chiral perturbation calculation indicates that the pion rescattering term should be significantly enhanced as compared with the traditional phenomenological treatment , and that this term should have substantial energy and momentum dependence .
an important consequence of this energy - momentum dependence is that , for a representative threshold kinematics and within the framework of our semiquantitative calculation , the rescattering term interferes destructively with the born - term in sharp contrast to the constructive interference obtained in the conventional treatment .
this destructive interference makes theoretical cross sections for @xmath0 much smaller than the experimental values , a feature that suggests the importance of the heavy - meson exchange contributions to explain the experimental data . .
And you have already written the first three sentences of the full article: recently meyer et al . @xcite carried out high - precision measurements of the total cross sections near threshold for the reaction @xmath1 these measurements were confirmed by bondar et al . @xcite .
the early theoretical calculations @xcite underestimate these s - wave @xmath2 production cross sections by a factor of @xmath35 .
the basic features of these early calculations may be summarized as follows ..
Please generate the next two sentences of the article | the pion production reactions are assumed to be described by the single nucleon process ( the born term ) , fig.1(a ) , and the @xmath4-wave pion rescattering process , fig.1(b ) .
the @xmath5-@xmath6 vertex for the born term is assumed to be given by the pseudovector interaction hamiltonian @xmath7 where @xmath8 is the axial coupling constant , and @xmath9 = 93 mev is the pion decay constant . |
9,752 | Suppose that you have an abstract for a scientific paper: the problem of the uniqueness of solutions during the evaluation of primary energy spectra in the knee region using an extensive air shower ( eas ) data set and the eas inverse approach is investigated .
it is shown that the unfolding of primary energy spectra in the knee region leads to mutually compensative pseudo solutions .
these solutions may be the reason for the observed disagreements in the elementary energy spectra of cosmic rays in the 1 - 100 pev energy range obtained from different experiments .
cosmic rays , primary energy spectra , extensive air shower , inverse problem .
96.40.pq , 96.40.de , 96.40.-z , 98.70.sa .
And you have already written the first three sentences of the full article: the extensive air shower ( eas ) inverse approach to a problem of the primary energy spectra reconstruction in the region of @xmath0 pev energies has been an essential tool in the past decade @xcite .
basically , it follows from the high accuracies of recent experiments @xcite and the availability of the eas simulation code @xcite , which was developed in the framework of contemporary interaction models in order to compute the kernel functions of a corresponding integral equation set @xcite . at the same time
, the energy spectra of primary ( @xmath1 and @xmath2 ) nuclei obtained from the kascade experiment @xcite using the eas inverse approach disagree with the same data from the ongoing gamma experiment @xcite , where parameterization of the eas inverse problem is used ..
Please generate the next two sentences of the article | + below , a peculiarity of the eas inverse problem is investigated , and one of the possible reasons for the observed disagreements between the energy spectra in @xcite and @xcite is considered in the framework of the sibyll @xcite interaction model . the paper is organized as follows : in section 2 the eas inverse approach and the definition of the problem of uniqueness is described .
it is shown , that the abundance of primary nuclear species leads to pseudo solutions for unfolded primary energy spectra . the existence and significance of the pseudo solutions |
9,753 | Suppose that you have an abstract for a scientific paper: the changes in excitation dependence of efficiency with temperature is modeled for a wurtzite ingan light - emitting diode .
the model incorporates bandstructure changes with carrier density arising from screening of quantum - confined stark effect .
bandstructure is computed by solving poisson and k@xmath0p equations in the envelop approximation .
the information is used in a dynamical model for populations in momentum - resolved electron and hole states .
application of the approach shows the interplay of quantum - well and barrier emissions giving rise to shape changes in efficiency versus current density with changing temperature , as observed in some experiments .
ocis : ( 230.3670 ) light - emitting diodes ; ( 230.5590 ) quantum - well , -wire and -dot devices ; ( 250.5590 ) quantum - well , -wire and -dot devices . .
And you have already written the first three sentences of the full article: considerable resources are being devoted to advancing ingan light - emitting diodes ( leds ) , largely because of solid - state lighting . of particular interest is improving device efficiency @xcite , especially the mitigation of efficiency degradation with increasing excitation , i.e. , efficiency droop shen , hader2,dellaney .
to arrive at a solution , it is important to understand the principal mechanism of emission together with the effects of carrier leakage @xcite , auger recombination @xcite , junction heating @xcite , carrier and defect delocalizations chichibu , smowton , hader1 . equally important
is the change in efficiency with temperature , not only for application but also for better understanding of the physics contributing to efficiency droop ..
Please generate the next two sentences of the article | this paper investigates led efficiency as functions of current density and lattice temperature .
the analysis uses a model that allows direct input of band - structure properties @xcite . |
9,754 | Suppose that you have an abstract for a scientific paper: we present @xmath0body simulations of intermediate - mass ( @xmath1 m@xmath2 ) young star clusters ( scs ) with three different metallicities ( @xmath3 , 0.1 and 1 z@xmath2 ) , including metal - dependent stellar evolution recipes and binary evolution . following recent theoretical models of wind mass loss and core collapse supernovae
, we assume that the mass of the stellar remnants depends on the metallicity of the progenitor stars .
in particular , massive metal - poor stars ( @xmath4 z@xmath2 ) are enabled to form massive stellar black holes ( msbhs , with mass @xmath5 m@xmath2 ) through direct collapse .
we find that three - body encounters , and especially dynamical exchanges , dominate the evolution of the msbhs formed in our simulations . in scs with @xmath3 and 0.1 z@xmath2 , about 75 per cent of simulated msbhs form from single stars and
become members of binaries through dynamical exchanges in the first 100 myr of the sc life .
this is a factor of @xmath6 more efficient than in the case of low - mass ( @xmath7 m@xmath2 ) stellar black holes .
a small but non - negligible fraction of msbhs power wind - accreting ( @xmath8 per cent ) and roche lobe overflow ( rlo , @xmath9 per cent ) binary systems .
the vast majority of msbh binaries that undergo wind accretion and/or rlo were born from dynamical exchange .
this result indicates that msbhs can power x - ray binaries in low - metallicity young scs , and is very promising to explain the association of many ultraluminous x - ray sources with low - metallicity and actively star forming environments .
black hole physics stars : binaries : general galaxies : star clusters : general x - rays : binaries methods : numerical stars : kinematics and dynamics . .
And you have already written the first three sentences of the full article: the mass spectrum of black holes ( bhs ) that form from the collapse of massive stars is highly uncertain .
an accurate dynamical mass estimate has been derived only for @xmath10 stellar bhs ( see table 2 of zel et al .
2010 for one of the most updated compilations , but see also lee , brown & wijers 2002 ; orosz 2003 ; narayan & mcclintock 2005 ) ..
Please generate the next two sentences of the article | most of the derived bh masses are in the range @xmath11 , with an apparent absence ( in x - ray binaries ) of bhs with @xmath12 m@xmath2 , difficult to explain with observational biases ( zel et al .
2010 ) . in the milky way ( mw ) , |
9,755 | Suppose that you have an abstract for a scientific paper: we present a simple setup to implement truly random number generator based on the measurement of the laser phase noise . from the entropy point of view
, we estimate the number of truly random bits that can be extracted from the sampled byte . with a simple method of adopting the @xmath0-least - significant - bit
, we amplify the entropy of the original bit sequence and realize a truly random bit generation rate of @xmath1 mbps .
the application of random number generator ( rng ) covers wide areas of cryptography , statistical sampling , computer simulations , etc .
traditionally , rng is implemented using the algorithm - based pseudo - random number generator ( prng ) , while in most application areas , prngs are not enough .
so far , it is commonly accepted that pure quantum process is the only solution for truly random number generator ( trng ) .
recently , two kinds of quantum noise of laser , phase noise and relaxation oscillation noise , are chosen to generate truly random bit sequence with high generation rate @xcite .
phase noise , directly measured using self - delayed homodyne detection @xcite , can be used to generate random bits with good randomness , but the final random number generation rate is limited by the laser linewidth ; relaxation oscillation noise , amplified by chaotic behavior , can be used to achieve ultra - high random bit generation rate @xcite , but the random bits generated by chaotic laser involve more classical noise ( not truly random ) and so can not have good results in three - sigma randomness tests @xcite . to generate an original random bit sequence ,
either an oscilloscope @xcite or an analog - digital - converter ( adc ) @xcite is available for high speed multi - bit per measurement data recording , but due to data size limitation in one scan process , using oscilloscope will reduce the generation rate for long random bit sequence .
multi - bit per measurement method increases the random number generation rate but introduces additional correlations....
And you have already written the first three sentences of the full article: ( color online ) schematic setup of trng based on the laser phase noise measurement using delayed self - homodyne method .
bs : beam splitter ; apd : silicon avalanche photodetector with the low ( high ) cutoff frequency of 50 khz ( 1 ghz ) ; adc : 8-bit binary analog - digital - converter working at @xmath4 mhz .
+ + fig ..
Please generate the next two sentences of the article | ( color online ) ( a ) the laser phase ( detection background ) noise of the laser field is observed at @xmath44 ma ( @xmath45 ma ) , while the threshold current is @xmath46 ma .
( b ) autocorrelation function of the beat signal vs time delay ( red line corresponds to autocorrelation of @xmath47 ) . |
9,756 | Suppose that you have an abstract for a scientific paper: the _ wind _ spacecraft carrying the transient gamma ray spectrometer ( tgrs ) moves in an extremely elliptical orbit that largely avoids earth s trapped radiation belts and albedo @xmath0-radiation .
the tgrs therefore enjoys a relatively low level of background that is also extremely stable .
we show how this stability enables modeling of the time variability of background lines , which in turn enables a novel technique of background subtraction to be used in the detection of transient astrophysical lines .
we apply a simple version of this method to the line at 478 kev that is expected to arise from nucleosynthesis of @xmath1be in nearby novae .
this search covers the entire southern ecliptic hemisphere during 19951997 , including five known individual events , and possible undiscovered individual events .
the tgrs design also uses _ wind _ s 3 s rotation period to modulate signals from the galactic center ( gc ) .
we use this feature of the instrument to search for a quasi - constant level of 478 kev emission from the accumulation of @xmath1be from several novae that are expected to occur in the direction of the gc during that isotope s 53 d half - life .
we derive upper limits on the transient ( single - nova ) emission which improve on previous limits by about an order of magnitude , and limits on the steady ( many - nova ) emission which represent a factor 2 improvement .
only weak limits can be placed on the key parameters in the nucleosynthesis and ejection of @xmath1be , however . .
And you have already written the first three sentences of the full article: although clasical novae occur rather frequently in our galaxy ( some tens of events per year ) , they are not expected to contribute greatly to the chemical enrichment of the galaxy because they eject relatively small masses of nuclear - processed material .
the rare cno nuclei @xmath2c , @xmath3n and @xmath4o are exceptions , and so is the light isotope @xmath1li , which is the topic of the present study ( hernanz & jos 2000 ) .
about 10% of the present galactic abundance of @xmath1li may have come from novae , which are one of the several sources ( mainly cosmic ray spallation and neutrino spallation in supernovae : cass , vangioni - flam & audouze 2001 ) that raise the @xmath1li abundance above the cosmologically - interesting value left by big bang nucleosynthesis ..
Please generate the next two sentences of the article | nova nucleosynthesis of @xmath1li is also of interest in that the @xmath1li is produced as unstable @xmath1be by the reaction @xmath5he(@xmath6,@xmath0)@xmath1be , where @xmath5he is another big bang isotope whose subsequent evolution must be accounted for .
the @xmath7-decay of @xmath1be with half - life 53.28 d is accompanied in 10.5% of cases by emission of a @xmath0-ray of energy 478 kev that potentially provides a direct measurement of the nova contribution if it can be detected . |
9,757 | Suppose that you have an abstract for a scientific paper: we discuss a dynamical mechanism of pion production from disoriented chiral condensates ( dcc ) .
it leads to an explosive production of pions via the parametric resonance mechanism , which is similar to the reheating mechanism in inflationary cosmology .
classically it is related with the instability in the solutions of the mathieu equation and we explore the quantum aspects of the mechanism . we show that nonlinearities and back reactions can be ignorable for sufficiently long time under the small amplitude approximations of background @xmath0 oscillations , which may be appropriate for the late stage of nonequilibrium phase transition .
it allows us to obtain an explicit quantum state of the produced pions and @xmath0 , the squeezed state of bcs type .
single particle distributions and two - pion correlation functions are computed within these approximations .
the results obtained illuminate the characteristic features of multi - pion states produced through the parametric amplification mechanism .
in particular , two - pion correlations of various charge combinations contain back - to - back correlations which can not be masked by the identical particle interference effect .
we suggest that the parametric resonance mechanism might be a cause of the long lasting amplification of low momentum modes in linear sigma model simulations .
# 1 # 1#1 # 1a^(#1)^ #1a^(#1 ) .
And you have already written the first three sentences of the full article: we now believe in quantum chromodynamics ( qcd ) as _ the _ theory of strong interaction . yet , the centauro and anti - centauro events that were found in cosmic ray experiments @xcite indicate some puzzling features .
the events are characterized by large fluctuations in the ratio of number of neutral pions to that of charged pions .
it appeared to be unlikely that such feature can be realized inside the conventional picture of hadronic interactions with `` soft '' qcd interaction , which implies more or less an independent emission of particles ..
Please generate the next two sentences of the article | however , several authors formulated a scenario which explains such features of the events based on the idea of formation of chirally misaligned domains , the disoriented chiral condensate ( dcc ) @xcite .
it requires that a `` hot '' matter forms during hadronic collisions in which the chiral symmetry is restored , and then it rapidly cools down so that chiral orientation of the pion fields can align to a random direction different from that of the vacuum . |
9,758 | Suppose that you have an abstract for a scientific paper: the recently discovered sharp peak in the @xmath0 ratio in relativistic heavy - ion collisions is discussed in the framework of the statistical model . in this model a rapid change is expected as the hadronic gas undergoes a transition from a baryon - dominated to a meson - dominated gas .
the transition occurs at a temperature @xmath1 = 140 mev and baryon chemical potential @xmath2 = 410 mev corresponding to an incident energy of @xmath3 = 8.2 gev .
the maximum in the @xmath4 ratio is well reproduced by the statistical model , but the change in the @xmath0 ratio is much less pronounced than the one observed by the na49 collaboration .
the calculated smooth increase of the @xmath5 ratio and the shape of the @xmath6 and @xmath7 ratios exhibiting maxima at different incident energies is consistent with the presently available experimental data .
we conclude that the measured particle ratios with @xmath8 deviations agree with a hadronic freeze - out scenario .
these deviations seem to occur just in the transition from baryon - dominated to meson - dominated freeze - out . , ,
, the na49 collaboration has recently performed a series of measurements of pb - pb collisions at 20 , 30 , 40 , 80 and 158 agev beam energies @xcite .
when these results are combined with measurements at lower beam energies from the ags @xcite they reveal an unusually sharp variation with beam energy in the @xmath9 , with @xmath10 , and @xmath0 ratios .
such a strong variation with energy does not occur in pp collisions and therefore indicates a major difference in heavy - ion collisions .
this transition has been referred to in ref .
@xcite as the `` horn '' .
a strong variation with energy of the @xmath9 ratio has been predicted on the basis of arguments put forward in @xcite .
it has also been suggested recently in ref .
@xcite that this is a signal of the special critical point of the qcd phase diagram @xcite at high baryon density . in this paper
we explore another , less spectacular ,....
And you have already written the first three sentences of the full article: we thank c. blume for his help with the na49 data .
we acknowledge the support of the german bundesministerium fr bildung und forschung ( bmbf ) , the polish state committee for scientific research ( kbn ) grant 2p03 ( 06925 ) , the national research foundation ( nrf , pretoria ) and the urc of the university of cape town .
50 m. gadzicki , ( na49 collaboration ) , j. phys ..
Please generate the next two sentences of the article | g : nucl . part .
phys . * 30 * ( 2004 ) s701 . |
9,759 | Suppose that you have an abstract for a scientific paper: we study a time - dependent 5d metric which contains a static 4d sub - metric whose 3d part is spherically symmetric . an expansion in the metric coefficient
allow us to obtain close - to schwarzschild approximation to a class of spherically - symmetric solutions .
using campbell s embedding theorem and the induced - matter formalism we obtain two 4d solutions .
one describes a source with the stiff equation of state believed to be applicable to dense astrophysical objects , and the other describes a spherical source with a radial heat flow .
pacs number(s ) : 04.20.jb , 11.10 kk .
And you have already written the first three sentences of the full article: campbell showed the theorem that any solution of the einstein equations in @xmath0 dimensions can be locally embedded in a ricci - flat manifold of @xmath1 dimensions whose field equations in terms of the ricci tensor are @xmath2 ( @xmath3).@xmath4 tavakol and coworkers have recently noted the relevance of this to the embedding of lower - dimensional ( possibly quantizeable ) gravity in 4d einstein gravity,@xmath5 and the technique is clearly applicable to the recovery of solutions of 4d general relativity from 10d superstrings , 11d supergravity and m - theory.@xmath6 a major application of campbell s theorem is to induced - matter theory , wherein solutions of the 4d einstein equations with matter are recovered from the 5d kaluza - klein equations in apparent vacuum.@xmath7 this approach has been applied to cosmology,@xmath8 clusters of galaxies@xmath9 and the solar system,@xmath10 where there is agreement with observational data .
it is valuable in application to general relativity , since solutions of the kaluza - klein equations can yield new solutions of the einstein equations . with regard to the latter
, spherically - symmetric sources such as stars can be modelled in the simplest way by the interior and exterior schwarzschild solutions . but to include the radiation outside a star , more complicated solutions are required.@xmath11 these include the vaidya metric which uses a retarded time coordinate to describe a radiating atmosphere,@xmath12 the metrics of herrera and coworkers wherein spheres of matter are matched to exterior spacetimes,@xmath13 and the metrics of glass and krisch which extend the vaidya solution to include both a radiation field and a string fluid.@xmath14 however , despite extensive work on star - like solutions of the 4d equations and the existence of campbell s theorem which shows that such can be embedded in the @xmath15d equations , not much work has been done on spherically - symmetric solutions of the 5d equations ..
Please generate the next two sentences of the article | notable exceptions are solutions which have an isothermal equation of state in 4d@xmath9 and ones which are flat in 5d but curved in 4d.@xmath16 we will therefore present an analysis of a class of 5d metrics , and illustrate their relevance by isolating two 4d solutions .
one describes a source with the stiff equation of state believed to be applicable to dense astrophysical objects , and the other describes a spherical source with radiation . |
9,760 | Suppose that you have an abstract for a scientific paper: we introduce a new disorder regime for directed polymers with one space and one time dimension that is accessed by scaling the inverse temperature parameter @xmath0 with the length of the polymer @xmath1 .
we scale @xmath2 for @xmath3 .
this scaling sits in between the usual weak disorder ( @xmath4 ) and strong disorder regimes ( @xmath5 ) .
the fluctuation exponents @xmath6 for the polymer endpoint and @xmath7 for the free energy depend on @xmath8 in this regime , with @xmath9 corresponding to the usual polymer exponents @xmath10 and @xmath11 corresponding to the simple random walk exponents @xmath12 . for @xmath13
the exponents interpolate linearly between these two extremes . at @xmath14
we exactly identify the limiting distribution of the free energy and the end point of the polymer . .
And you have already written the first three sentences of the full article: directed polymers in disordered media is a model of a variety of physical phenomena .
it describes vortex lines in superconductors @xcite , domain walls @xcite , roughness of crack interfaces @xcite , burgers turbulence @xcite and the kpz equation @xcite .
it provides a simple model in which the more difficult predictions of spin glasses can be tested and is related @xcite to the phase boundary in the 2d ising model . starting with @xcite.
Please generate the next two sentences of the article | , they have been the subject of intensive study @xcite over the last twenty - five years . in the setting of the @xmath15-dimensional integer lattice ,
the polymer measure is a random probability measure on the set of paths of @xmath15-dimensional nearest neighbour lattice walks . |
9,761 | Suppose that you have an abstract for a scientific paper: we have obtained a far - ultraviolet spectrum of the x - ray binary hercules x-1/hz herculis using the hopkins ultraviolet telescope aboard the astro-1 space shuttle mission in 1990 december .
this is the first spectrum of her x-1 that extends down to the lyman limit at 912 .
we observed emission lines of ovi@xmath0 , nv@xmath1 , and civ@xmath2 , and the far uv continuum extending to the lyman limit .
we examine the conditions of the emitting gas through line strengths , line ratios , and doublet ratios .
the uv flux is lower by about a factor of 2 than expected at the orbital phase of the observation .
we model the uv continuum with a simple power - law and with a detailed model of an x - ray - illuminated accretion disk and companion star .
the power - law provides a superior fit , as the detailed model predicts too little flux below 1200 .
we note , however , that there are uncertainties in the interstellar reddening , in the background airglow spectrum , and in the long - term phase of the accretion disk .
we have searched the data for uv line and continuum pulsations near the neutron star spin period but found none at a detectable level . .
And you have already written the first three sentences of the full article: hercules x-1/hz herculis is a low mass x - ray binary system consisting of a @xmath3 neutron star and a @xmath4 a dwarf star locked in orbit about each other with a period of 1.7 d ( deeter et al . 1991 , and references therein ) .
the x - ray source is eclipsed by the a star for 0.24 d of each period , indicating an orbital inclination near 90@xmath5 .
the spectral type of the a star varies with orbital phase from late b / early a to late a / early f such that the later spectral types correspond to eclipse and the earlier spectral types correspond to 1/2 an orbit later ( when x - ray heating of the a star should be most apparent see milgrom & salpeter 1975 ) ..
Please generate the next two sentences of the article | mass transfer , which may be periodic , feeds an accretion disk around the neutron star .
accretion onto the neutron star itself , which has a magnetic field of @xmath6 gauss , occurs on the magnetic poles ( gruber et al . 1980 ; voges et al . |
9,762 | Suppose that you have an abstract for a scientific paper: we present a theoretical method for a _ direct _ evaluation of the average and reliability error exponents in low - density parity - check error - correcting codes using methods of statistical physics .
results for the binary symmetric channel ( bsc ) are presented for codes of both finite and infinite connectivity . .
And you have already written the first three sentences of the full article: low - density parity - check codes ( ldpc ) have attracted significant interest in recent years due to their simplicity and exceptionally high performance @xcite .
their simplicity and inherent randomness make them amenable to analysis using established methods in the area of statistical physics .
these have been employed in a number of papers @xcite-@xcite to gain insight into the properties of ldpc codes and to evaluate their performance ..
Please generate the next two sentences of the article | these studies include the evaluation of critical noise levels for given codes @xcite , an exact calculation of weight and magnetisation enumerators @xcite , the performance of irregular codes @xcite , properties of codes in real - valued channels @xcite , and the derivation of bounds for the reliability exponent @xcite , to name but a few .
these studies also represent the interdisciplinary nature of this research area and illustrate the successful interaction between researchers in the two disciplines . |
9,763 | Suppose that you have an abstract for a scientific paper: while the mammalian- and the avian inner ears have well defined tonotopic organizations as well as hair cells specialized for motile and sensing roles , the structural organization of the avian ear is different from its mammalian cochlear counterpart .
presumably this difference stems from the difference in the way motile hair cells function .
short hair cells , whose role is considered analogous to mammalian outer hair cells , presumably depends on their hair bundles , and not motility of their cell body , in providing the motile elements of the cochlear amplifier .
this report focuses on the role of the avian tectorial membrane , specifically by addressing the question , `` why is the avian tectorial membrane tapered from the neural to the abneural direction ? ''
address = otolaryngology & head and neck surgery , stanford university , stanford , ca 93405 , usa , altaddress = nidcd , nih , bethesda , md 20892 , usa address = otolaryngology & head and neck surgery , stanford university , stanford , ca 93405 , usa , altaddress = molecular & cellular physiology , stanford university , stanford , ca 93405 , usa .
And you have already written the first three sentences of the full article: the avian and mammalian ears have similarities and differences .
the innervation pattern of avian tall hair cells resembles that of mammalian inner hair cells in having primarily afferent innervation , suggesting their role as the primary sensor .
in contrast , the innervation pattern of short hair cells in the avian ear is exclusively efferent and resembles that of outer hair cells , suggesting the role of motor element in the cochlear amplifier @xcite . since bending of hair bundles ( including tilting motion of the apical surface of hair cells @xcite ) is the only motile response in short hair cells , such a physiological role requires that the hair bundles of short hair cells exert force between the tectorial membrane and the basilar papilla ..
Please generate the next two sentences of the article | there are marked differences .
one such difference is the absence of pillar cells and the tunnel of corti in the avian ear . |
9,764 | Suppose that you have an abstract for a scientific paper: higher - order low - rank tensors naturally arise in many applications including hyperspectral data recovery , video inpainting , seismic data reconstruction , and so on . we propose a new model to recover a low - rank tensor by simultaneously performing low - rank matrix factorizations to the all - mode matricizations of the underlying tensor .
an alternating minimization algorithm is applied to solve the model , along with two adaptive rank - adjusting strategies when the exact rank is not known .
phase transition plots reveal that our algorithm can recover a variety of synthetic low - rank tensors from significantly fewer samples than the compared methods , which include a matrix completion method applied to tensor recovery and two state - of - the - art tensor completion methods .
further tests on real - world data show similar advantages .
although our model is non - convex , our algorithm performs consistently throughout the tests and gives better results than the compared methods , some of which are based on convex models . in addition , subsequence convergence of our algorithm can be established in the sense that any limit point of the iterates satisfies the kkt condtions .
yangyang xu ruru hao wotao yin zhixun su .
And you have already written the first three sentences of the full article: _ tensor _ is a generalization of _ vector _ and _ matrix_. a vector is a first - order ( also called one - way or one - mode ) tensor , and a matrix is a second - order tensor .
higher - order tensor arises in many applications such as 3d image reconstruction @xcite , video inpainting @xcite , hyperspectral data recovery @xcite , higher - order web link analysis @xcite , personalized web search @xcite , and seismic data reconstruction @xcite . in this paper
, we focus on the recovery of higher - order tensors that are ( exactly or approximately ) low - rank and have missing entries ..
Please generate the next two sentences of the article | we dub the problem as _ low - rank tensor completion _ ( lrtc ) . the introduced model and algorithm
can be extended in a rather straightforward way to recovering low - rank tensors from their linear measurements . |
9,765 | Suppose that you have an abstract for a scientific paper: we discuss how adiabatic potentials can be used to create addressable lattices on a subwavelength scale , which can be used as a tool for local operations and readout within a lattice substructure , while taking advantage of the faster timescales and higher energy and temperature scales determined by the shorter lattice spacing . for alkaline - earth - like atoms with non - zero nuclear spin ,
these potentials can be made state dependent , for which we give specific examples with @xmath0yb atoms .
we discuss in detail the limitations in generating the lattice potentials , in particular non - adiabatic losses , and show that the loss rates can always be made exponentially small by increasing the laser power . .
And you have already written the first three sentences of the full article: optical lattices in 3d generated by counterpropagating laser fields provide a periodic array of microtraps for cold atoms , and implement quantum lattice models governed by hubbard hamiltonians @xcite .
this is of interest both in the study of strongly correlated systems from condensed matter physics , and in the implementation of quantum information processing .
two key elements of cold atom dynamics in 3d optical lattices are : ( i ) the lattice spacing is bounded below by the wavelength @xmath1 . therefore , all the relevant time , energy and temperature scales are determined by the recoil energy , @xmath2 , where @xmath3 is the wavenumber , and @xmath4 is the the mass of the atom ..
Please generate the next two sentences of the article | in particular , the hopping matrix element between neighbouring sites within the region of validity of the single - band hubbard model is limited by @xmath5 .
this limits all corresponding timescales , for example the timescale over which entanglement can be generated using exchange interactions @xcite . |
9,766 | Suppose that you have an abstract for a scientific paper: we establish a general relation between dispersion forces . first , based on qed in causal media , leading - order perturbation theory
is used to express both the single - atom casimir - polder and the two - atom van der waals potentials in terms of the atomic polarizabilities and the green tensor for the body - assisted electromagnetic field .
endowed with this geometry - independent framework , we then employ the born expansion of the green tensor together with the clausius - mosotti relation to prove that the macroscopic casimir - polder potential of an atom in the presence of dielectric bodies is due to an infinite sum of its microscopic many - atom van der waals interactions with the atoms comprising the bodies .
this theorem holds for inhomogeneous , dispersing , and absorbing bodies of arbitrary shapes and arbitrary atomic composition on an arbitrary background of additional magnetodielectric bodies . .
And you have already written the first three sentences of the full article: the relation between the casimir - polder ( cp ) interaction of a single atom with a body @xcite and its van der waals ( vdw ) interaction with the atoms comprising the body @xcite was first discussed in detail by renne @xcite , with special emphasis on an atom interacting with a dielectric half space .
approaching the problem from the microscopic side and modelling all atoms by identical harmonic oscillators , he showed that the sum of all many - atom vdw interactions between the single atom and the body atoms corresponds to the result for the cp potential derived earlier on the basis of a macroscopic approach @xcite .
milonni and lerner generalised this result to bodies of arbitrary shapes @xcite ..
Please generate the next two sentences of the article | using the ewald - oseen extinction theorem which follows from the clausius - mosotti relation , they demonstrated that the cp potential of an atom in the presence of a nonabsorbing homogeneous dielectric body can be obtained by summing over an infinite series of many - atom vdw potentials . in this paper , we approach the problem from the macroscopic side and under more general conditions . to that end , based on macroscopic qed in linear , causal media ( sec .
[ sec2 ] ) , we first consider the cp interaction of an atom with a macroscopic body as well as the vdw interaction of two atoms ( sec . |
9,767 | Suppose that you have an abstract for a scientific paper: the luttinger liquid in which the concentration of electrons varies randomly with coordinate is considered .
we study the fluctuations of the tunnel conductance , caused by the randomness in the concentration .
if the concentration changes slowly on the scale of the fermi wavelength , its prime role reduces to the scattering of the plasmon waves , propagating along the system . as a result of such a scattering , plasmons get localized .
we show that the localization length , @xmath0 , of a plasmon with frequency @xmath1 is inverse proportional to the square of the interaction strength and changes with frequency as @xmath2 .
if the relative variation of the concentration is small , the randomness induced correction to the tunnel conductance , @xmath3 , where @xmath4 is the applied bias , can be expressed through the spectral characteristics of the localized plasmons .
the magnitude of the correction , @xmath5 , increases with @xmath4 as @xmath6 .
the typical period of the fluctuations in @xmath3 is of the order of @xmath4 . at a fixed @xmath4 , the correlator of @xmath7 at different points of the liquid falls off with distance as a power law and oscillates with the period which is one half of the wavelength of a plasmon with frequency @xmath8 . .
And you have already written the first three sentences of the full article: it is well known that the density of states in a pure one dimensional interacting electron gas ( luttinger liquid ) vanishes as a power law in the vicinity of the fermi level @xcite : @xmath9 , where the exponent is determined by the interaction strength .
such a behavior should reveal itself in the dependence of the differential tunnel conductance on the applied bias : @xmath10 .
it is obvious that the presence of a disorder would perturb the local value of the density of states and , thus , cause some random correction , @xmath3 , to the conductance ..
Please generate the next two sentences of the article | then the relevant questions are : \i ) what is the typical magnitude of @xmath7 for a given realization of the disorder ?
\ii ) how the values of @xmath7 at different voltages are correlated ? |
9,768 | Suppose that you have an abstract for a scientific paper: this paper is devoted to the mathematical analysis of a time - domain electromagnetic scattering by periodic structures which are known as diffraction gratings .
the scattering problem is reduced equivalently into an initial - boundary value problem in a bounded domain by using an exact transparent boundary condition .
the well - posedness and stability of the solution are established for the reduced problem . moreover , a priori energy estimates are obtained with minimum regularity requirement for the data and explicit dependence on the time . .
And you have already written the first three sentences of the full article: this paper is concerned with the mathematical analysis of an electromagnetic scattering problem in periodic structures , where the wave propagation is governed by the time - domain maxwell equations . the scattering theory in periodic diffractive structures ,
also known as diffraction gratings , has applications in many cutting - edge scientific areas including ultra - fast and high - energy lasers , space flight instruments , astronomy , and synchrotron spectrometers .
a good introduction can be found in @xcite to diffraction grating problems and various numerical approaches ..
Please generate the next two sentences of the article | the book @xcite contains descriptions of several mathematical problems that arise in diffractive optics modeling in industry .
some more recent developments are addressed in @xcite on theory , analysis , and computational techniques of diffractive optics . |
9,769 | Suppose that you have an abstract for a scientific paper: the direct nuclear x ray emission of the ultraluminous iras galaxy ngc 6240 has been observed for the first time by _ beppo_sax .
it is seen through an absorber with @xmath0 @xmath1 . the 2 - 10 kev x
ray luminosity of @xmath2 erg s@xmath3 definitely proves that a powerful agn is hosted in this galaxy , despite the liner optical appearance . assuming the typical @xmath4 ratio for quasars
, our result implies that it is the agn and not the starburst that dominates the energy output of ngc 6240 . .
And you have already written the first three sentences of the full article: one of the major open problems with ultraluminous infrared galaxies ( ulirg ) is whether they host active nuclei at their centers . in at least a fraction of objects
, there is circumstantial evidence that this is the case .
one of the best examples in this respect is ngc 6240 is the limiting criterion for ulirg , strictly speaking ngc 6240 belongs to this class only if @xmath565 km s@xmath3 mpc@xmath3 ; genzel et al ..
Please generate the next two sentences of the article | ( 1998 ) . ] , a well known source in which the presence of two nuclei ( fried & schulz 1983 ) suggests an ongoing galaxy merger .
indications of the presence of an agn come mainly from x rays : the flat 210 kev x ray spectrum and the prominent iron line complex observed by asca ( iwasawa & comastri 1998 ) are very similar to those of ngc 1068 ( iwasawa , fabian & matt 1997 ; matt et al . 1997 and references therein ) and suggest reflection from cold and warm matter of an otherwise invisible nuclear component . on the other hand , in the optical spectrum all the diagnostic line ratios point towards a classification as a liner ( e.g. veilleux et al . 1995 ) , and the iso sws diagnostic diagram places ngc 6240 in the region of star formation dominance ( genzel et al . 1998 ) . in soft x |
9,770 | Suppose that you have an abstract for a scientific paper: we have started the development of a detector system , sensitive to single photons in the ev energy range , to be suitably coupled to one of the cast magnet ports .
this system should open to cast a window on possible detection of low energy axion like particles emitted by the sun .
preliminary tests have involved a cooled photomultiplier tube coupled to the cast magnet via a galileian telescope and a switched 40 m long optical fiber .
this system has reached the limit background level of the detector alone in ideal conditions , and two solar tracking runs have been performed with it at cast .
such a measurement has never been done before with an axion helioscope .
we will present results from these runs and briefly discuss future detector developments . .
And you have already written the first three sentences of the full article: it has recently been pointed out @xcite that many phenomena taking place in the sun , especially in its corona and in its magnetic field , are far from being completely understood .
the production by the sun of axion like particles ( alps ) and their subsequent interactions in the solar environment could provide a key to interpreting the physical mechanisms underlying these phenomena . these , and other considerations led to starting a search with the cast magnetic helioscope @xcite for hypothetical alps emitted by the sun in the energy range below 100 ev . the first step of this search , which will be reported here , has involved looking for 2 - 4 ev photons produced in the cast magnet bore by the primakoff @xcite conversion into photons of solar alps in the latter energy range . the short term objective was to efficiently couple a detector system sensitive in the ev energy range to a cast magnet bore and evaluate its background in normal operating conditions .
the long term objective of the effort is attempting to detect , using sensors with the appropriate spectral sensitivity and good enough background , `` low''-energy ( tens of ev s ) photons generated in the cast helioscope by possible interactions of low - energy solar alps ..
Please generate the next two sentences of the article | we will briefly describe the detector system , which has been developed for this purpose under the barbe project financed by the italian istituto nazionale di fisica nucleare ( infn ) , along with the coupling of this system to the cast magnet .
finally , the data taking campaigns will be discussed and a summary of the data presented . |
9,771 | Suppose that you have an abstract for a scientific paper: in this paper , delay constrained performance of a multiple - input multiple - output ( mimo ) communication system in a dense environment with co - channel interference is investigated .
we apply orthogonal space - time block coding ( ostbc ) at the transmitter , and for alleviating the high complexity and cost of the mimo system , receive antenna selection ( ras ) scheme is employed in the downlink . here , for simple and cheap mobile handsets , one antenna is chosen at the receiver in each utilization of the channel . under these assumptions , a maximum constant arrival rate with the delay quality - of - service ( qos ) guarantee in a wireless channel
is extracted .
we obtain a closed - form solution for the effective capacity of the mimo - ostbc channel with the ras scheme in a quasi - static rayleigh fading conditions and co - channel interference .
after all , the numerical simulations are provided and verified the theoretical results .
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: delay sensitive applications such as audio / video conferencing and real - time control require low end - to - end delay @xcite . in these applications ,
when the ultimate delay of a data packet exceeds a certain threshold , the packet is useless and has to be dropped .
so , the delay violation probability is a suitable quality of service ( qos ) performance metric here @xcite ..
Please generate the next two sentences of the article | in wireless telecommunication systems and a proper channel condition , transmission with high data rate can be accomplished .
in contrast , in a severe condition , the data rate decreases and probably becomes zero . |
9,772 | Suppose that you have an abstract for a scientific paper: we present li abundances for 14 solar type stars in the intermediate age ( @xmath0 gyr ) clusters ic 4651 and ngc 3680 .
the @xmath1 n(li ) vs. effective temperature distributions are compared with those of the similar age cluster ngc 752 , of the younger hyades ( 600 myr ) and of the older m 67 ( 4.5 gyr ) and ngc 188 ( 67 gyr ) clusters .
neither ic 4651 nor ngc 3680 show the dispersion in li which is observed in m 67 .
the 2 gyr clusters have very similar li vs. t@xmath2 distributions ; in addition , stars in the upper envelope of the m 67 distribution have the same li content as stars in the 2 gyr clusters , suggesting that either they have not suffered any significant depletion between @xmath3 2 and 4.5 gyr or they had a much slower li depletion .
mechanisms that lead to li depletion on the main sequence are discussed in the light of these observations .
none of the existing models seem to reproduce well the observed features . .
And you have already written the first three sentences of the full article: understanding the processes that lead to lithium destruction on the main sequence ( ms ) provides powerful diagnostics of stellar structure and evolution and of mixing mechanisms in stars .
rccccl + & & & & & + + & & & & & + name & ( b@xmath4v)@xmath5 & ew(li i ) & t@xmath2 & @xmath1 n(li ) & rv + ( 1 ) & & ( m ) & ( k ) & & info . ( 2 ) + eg 7 & 0.56 & 70 @xmath6 15 & 6061 & 2.7 @xmath7 & s + eg 45 & 0.57 & 44 @xmath6 7 & 6016 & 2.4 @xmath7 & s + at 38 & 0.54 & 35 @xmath6 8 & 6122 & 2.4 @xmath8 & + at 39 & 0.54 & 49 @xmath6 10 & 6114 & 2.6 @xmath8 & + at 1108 & 0.53 & 47 @xmath6 10 & 6189 & 2.6 @xmath8 & sb + at 1109 & 0.62 & 61 @xmath6 15 & 5814 & 2.4 @xmath9 & + at 1225 & 0.51 & 64 @xmath6 7 & 6235 & 2.8 @xmath9 & s + at 2207 & 0.59 & 44 @xmath6 10 & 5908 & 2.3 @xmath9 & + at 2105 & 0.54 & 48 @xmath6 10 & 6110 & 2.5 @xmath9 & s + at 3226 & 0.58 & 49 @xmath6 8 & 5967 & 2.4 @xmath8 & nm + at 4226 & 0.62 & 31 @xmath6 10 & 5795 & 2.1 @xmath9 & + & & & & & + + + & & & & & + + & & & & & + name & ( b@xmath4v)@xmath5 & ew(li i ) & t@xmath2 & @xmath1 n(li ) & rv + & & ( m ) & ( k ) & & info .
+ 23 & 0.58 & 46@xmath6 5 & 5971 & 2.41 @xmath6 0.04 & sb1 + 60 & 0.59 & 48@xmath6 6 & 5924 & 2.38 @xmath6 0.05 & m ?.
Please generate the next two sentences of the article | + 70 & 0.60 & 42@xmath6 5 & 5884 & 2.28 @xmath6 0.04 & m + 4114 & 0.58 & 51@xmath6 6 & 5951 & 2.44 @xmath6 0.05 & m ?
+ & & & & & + + surveys of li among cluster and field stars have shown that standard models ( i.e. , those that take into account convecting mixing only ) are in contradiction with many of the observational features ( see deliyannis @xcite ; jeffries @xcite ; pasquini @xcite , and references therein for recent reviews ) . focusing on solar type stars , at least two results in strong disagreement with model predictions have been found : _ |
9,773 | Suppose that you have an abstract for a scientific paper: we present a simple protocol to purify a coherent state superposition that has undergone a linear lossy channel .
the scheme constitutes only a single beam splitter and a homodyne detector , and thus experimentally feasible . in practice
, a superposition of coherent states is transformed into a classical mixture of coherent states by linear loss , which is usually the dominant decoherence mechanism in optical systems .
we also address the possibility of producing a larger amplitude superposition state from decohered states , and show that in most cases the decoherence of the states are amplified along with the amplitude . .
And you have already written the first three sentences of the full article: in optical communication systems , information is often carried by states with gaussian statistics ; the coherent state is a simple and very important example .
the processing of these states in the quantum domain is now a major concern toward attaining ultimate capacity of bosonic channels @xcite , and also the construction of quantum networks and computers @xcite . toward these applications , it is important to generate and manipulate superpositions of pure gaussian states .
in fact , certain types of such superposition states can be used as ancillary states to build up a universal set of operations to construct an arbitrary processor @xcite ..
Please generate the next two sentences of the article | ( see also ref @xcite for its experimental perspectives . )
these states are essentially non - gaussian states , and are easily destroyed even by a small amount of losses . in practice , it is not easy to prepare in labs the state that preserves enough purity and useful non - gaussian properties |
9,774 | Suppose that you have an abstract for a scientific paper: we use molecular dynamic simulations to investigate the relation between the presence of packing defects in a glass - former and the spontaneous cooperative motions called dynamic heterogeneity . for that purpose
we use a simple diatomic glass - former and add a small number of larger or smaller diatomic probes .
the diluted probes modify locally the packing , inducing structural defects in the liquid , while we find that the number of defects is small enough not to disturb the average structure .
we find that a small packing modification around a few molecules can deeply influence the dynamics of the whole liquid , when supercooled .
when we use small probe molecules , the dynamics accelerates and the dynamic heterogeneity decreases .
in contrast , for large probes the dynamics slows down and the dynamic heterogeneity increases .
the induced heterogeneities and transport coefficient modification increase when the temperature decreases and disappear around the onset temperature of the cage dynamics . .
And you have already written the first three sentences of the full article: the spontaneous appearance of cooperative motions called dynamic heterogeneity ( dh ) when liquids are supercooled @xcite has been extensively studied during the last decade , as scientists were searching for a cooperative mechanism at the origin of the glass - transition . despite large efforts in that direction of research however , the origin of the dynamic heterogeneity and the effect of these cooperative motions on the liquid dynamics still remain elusive .
it is widely thought that dhs appear due to the presence of some defects inside the low temperature liquid , that could be structural ( a local packing fluctuation ) or purely dynamical ( excitations ) .
the resulting excitations ( arising directly or from structural defects ) then grow due to facilitation@xcite processes , eventually disappearing at large timescales due to thermal diffusion . in 2004 ,.
Please generate the next two sentences of the article | asaph widmer - cooper and coworkers@xcite showed that dhs appear preferentially in some regions of the liquid , a result that strongly suggests a connection between the local structure and the dhs . in 2007 ,
laura kaufman s group @xcite studied the effect of probes larger than the medium molecules on the dynamics of supercooled liquids . |
9,775 | Suppose that you have an abstract for a scientific paper: chromium based inverse heusler compounds of the type cr@xmath0yz ( y = co , fe ; z = al , ga , in , si , ge , sn ) have been proposed as fully compensated half - metallic ferrimagnets .
such materials are of large interest for spintronics because they combine small magnetic moment with high spin polarization over a wide temperature range .
we assess their thermodynamic stability by their formation enthalpies obtained from density functional theory calculations .
all compounds under investigation are unstable .
cr@xmath0fesi and cr@xmath0coal are stable with respect to the elemental constituents , but decompose into binary phases .
cr@xmath0fege , cr@xmath0coga , cr@xmath0fesn and cr@xmath0coin are found to be unstable with respect to their elemental constituents .
we identify possible binary decompositions . .
And you have already written the first three sentences of the full article: fully compensated half - metallic ferrimagnets ( also known as half - metallic antiferromagnets ) @xcite have promising properties for spintronics . due to their internal spin compensation ,
the total moment is ( nearly ) zero at low temperature , yet the possibly strong local moments allow for high curie temperatures .
however , approaching the curie temperature one expects to find a non - zero total magnetic moment @xcite . in conjunction with possible appearance of half - metallicity.
Please generate the next two sentences of the article | , such materials would be ideal electrode materials for spin transfer torque switching devices and other advanced applications @xcite . among the inverse heusler compounds ( space group @xmath1 , prototype hg@xmath0cuti ) @xcite , several compositions with 24 valence electrons
have been identified which could have these unusual properties , in particular cr@xmath0coga and cr@xmath0fege @xcite . |
9,776 | Suppose that you have an abstract for a scientific paper: recent lhc data suggest an excess in the higgs decay channels into @xmath0 and @xmath1 at @xmath2125 gev .
the current excess in the diphoton channel is twice that expected from a standard model higgs ; whilst this may well change with more statistics , it is interesting to consider the implications should the result persist . here
, we assess whether the nmssm with a neutralino dark matter candidate could explain this excess when astrophysical constraints ( e.g. no overproduction of gamma rays and radio emission in the galaxy , no anomalous excess in the dark matter direct detection experiments and no dark matter overabundance ) are imposed on the neutralino .
this enables us to disregard unphysical regions of the parameter space even though the higgs signal is compatible with the observed excess .
the result of our analysis is that there are configurations of the parameter space which can explain the signal strength reported by the atlas and cms collaborations for a higgs mass within the required range .
should the observed signal strength finally be compatible with standard model expectations , it would be difficult to distinguish between the discovery of standard model higgs and a sm - like higgs from the nmssm , unless one performs dedicated searches of very light higgs bosons and possibly investigate peculiar signatures of supersymmetric particles .
we also propose a new jets + missing @xmath3 signal for the case where the lsp is a singlino - like neutralino . .
And you have already written the first three sentences of the full article: the lhc collaborations have reported new results on the search for the standard model higgs , @xmath4 @xcite . by combining analyses ,
the atlas collaboration has excluded the sm higgs in the mass range @xmath5 and @xmath6 at 95%cl with an integrated luminosity up to @xmath7 .
similarly , the cms collaboration excluded a sm higgs in the range @xmath8 at 95%cl with integrated luminosity of @xmath9 ..
Please generate the next two sentences of the article | furthermore , atlas reported an excess at 2.8@xmath10 in the @xmath11 decay channel , consistent with a higgs mass @xmath12 gev @xcite .
this signal is larger than expected from a sm higgs ( with signal strength @xmath13 ) and might favour new physics . |
9,777 | Suppose that you have an abstract for a scientific paper: qos - aware applications can satisfy not only the functional requirements of the customers , but also the qos requirements .
qos - aware web service orchestration translates the qos requirements of the customers into those of its component web services . in a system viewpoint , we discuss issues on qos - aware web service orchestration and design a typical qos - aware web service orchestration engine called qos - wsoe .
more importantly , we establish a formal model of qos - wsoe based on actor systems theory . within the formal model
, we use a three - layered pyramidal structure to capture the requirements of the customers with a concept named qos - aware wso service , characteristics of qos - wsoe with a concept named qos - aware wso system , and structures and behaviors of qos - wsoe with a concept named qos - aware wso behavior .
conclusions showing that a system with qos - aware wso behavior is a qos - aware wso system and further can provide qos - aware wso service are drawn .
[ firstpage ] web services ; web service orchestration ; web service orchestration engine ; actor systems ; qos ; formal model .
And you have already written the first three sentences of the full article: web service ( ws ) is a new distributed component which emerged about ten years ago , which uses wsdl@xcite as its interface description language , soap@xcite as its communication protocol and uddi@xcite as its directory service . because ws uses the web as its provision platform , it is suitable to be used to develop cross - organizational business integrations .
cross - organizational business processes are usual forms in e - commerce that orchestrate some business activities into a workflow .
ws orchestration ( wso ) provides a solution for such business process based on ws technologies , hereby representing a business process where business activities are modeled as component wses . from a ws viewpoint.
Please generate the next two sentences of the article | , wso provides a workflow - like pattern to orchestrate existing wses to create a new composite ws , and embodies the added values of ws .
in particular , we use the term wso , rather than another term |
9,778 | Suppose that you have an abstract for a scientific paper: we study the dimensional reduction of fermions , both in the symmetric and in the broken phase of the 3-d gross - neveu model at large @xmath0 . in particular ,
in the broken phase we construct an exact solution for a stable brane world consisting of a domain wall and an anti - wall . a left - handed 2-d fermion localized on the domain wall and a right - handed fermion localized on the anti - wall
communicate with each other through the 3-d bulk . in this way they are bound together to form a dirac fermion of mass @xmath1 . as a consequence of asymptotic freedom of the 2-d gross - neveu model , the 2-d correlation length @xmath2 increases exponentially with the brane separation .
hence , from the low - energy point of view of a 2-d observer , the separation of the branes appears very small and the world becomes indistinguishable from a 2-d space - time .
our toy model provides a mechanism for brane stabilization : branes made of fermions may be stable due to their baryon asymmetry .
ironically , our brane world is stable only if it has an extreme baryon asymmetry with all states in this `` world '' being completely filled .
addtoresetequationsection preprint hu - ep-03/58 , sfb - cpp-03 - 40 .
And you have already written the first three sentences of the full article: why is gravity so weak ? or equivalently , why are the proton ( and other hadrons ) so light compared to the planck scale ? as wilczek has explained nicely @xcite , the solution to this hierarchy puzzle results from asymptotic freedom . without any fine - tuning of the bare gauge coupling at distances as short as the planck length ,
a 4-d non - abelian gauge theory like qcd produces a correlation length @xmath3 that is larger than the shortest length scale in the problem , by a factor exponentially large in the inverse coupling .
the inverse correlation length defines a mass scale @xmath4 the proton mass in wilczek s example that is hence exponentially smaller than the planck scale ..
Please generate the next two sentences of the article | since we consist mostly of these very light particles ( protons and neutrons ) in natural units of their mass we experience gravity as a very weak force .
lattice gauge theorists benefit from the absence of a hierarchy problem in numerical simulations of gauge theories . in this case the shortest length scale ( and hence the analog of the planck length ) is the lattice spacing . |
9,779 | Suppose that you have an abstract for a scientific paper: the main aim of this paper is to extend the early approach to quantum cosmogenesis provided by fomin .
his approach was developed independently to the well - known tryon description of the creation of the closed universe as a process of quantum fluctuation of vacuum .
we apply the fomin concept to derive the cosmological observables .
we argue that fomin s idea from his 1973 work , in contrast to tryon s one has impact on the current universe models and the proposed extension of his theory now can be tested by distant supernovae snia .
fomin s idea of the creation of the universe is based on the intersection of two fundamental theories : general relativity and quantum field theory with the contemporary cosmological models with dark energy . as a result of comparison with contemporary approaches concerning dark energy
, we found out that fomin s idea appears in the context of the present acceleration of the universe explanation : cosmological models with decaying vacuum .
contemporary it appears in the form of ricci scalar dark energy connected with the holographic principle .
we show also that the fomin model admits the bounce instead of the initial singularity .
we demonstrate that the fomin model of cosmogenesis can be falsified and using snia data the values of model parameters is in agreement with observations . .
And you have already written the first three sentences of the full article: cosmogony is defined as a study of the origin ( cosmogenesis ) of the universe in the physical aspect .
it asks the question how the universe came into being . by comparing this process with human life , we called the birth of the universe cosmogenesis @xcite . among different conceptions of cosmogenesis which offer the possibility of describing the origin of the universe as a physical process
, there are cosmogenic theories of the spontaneous creation from vacuum instability . according to these theories ,.
Please generate the next two sentences of the article | the universe was created in a spontaneous way , from a quantum fluctuation .
edward tryon @xcite is usually considered as the scientist who first supported such theories in 1973 by arguing that total mechanical energy of the closed universe is zero and effects of quantum fluctuation of the vacuum were important when the universe was coming to the existence . |
9,780 | Suppose that you have an abstract for a scientific paper: we prove the strong converse for the @xmath0-source gaussian multiple access channel ( mac ) .
in particular , we show that any rate tuple that can be supported by a sequence of codes with asymptotic average error probability less than one must lie in the cover - wyner capacity region .
our proof consists of the following .
first , we perform an expurgation step to convert any given sequence of codes with asymptotic average error probability less than one to codes with asymptotic maximal error probability less than one .
second , we quantize the input alphabets with an appropriately chosen resolution . upon quantization , we apply the wringing technique ( by ahlswede ) on the quantized inputs to obtain further subcodes from the subcodes obtained in the expurgation step so that the resultant correlations among the symbols transmitted by the different sources vanish as the blocklength grows .
finally , we derive upper bounds on achievable sum - rates of the subcodes in terms of the type - ii error of a binary hypothesis test .
these upper bounds are then simplified through judicious choices of auxiliary output distributions .
our strong converse result carries over to the gaussian interference channel under strong interference as long as the sum of the two asymptotic average error probabilities less than one .
gaussian multiple access channel , strong converse , binary hypothesis testing , expurgation , wringing technique .
And you have already written the first three sentences of the full article: the multiple access channel ( mac ) is one of the most well - studied problems in network information theory @xcite .
the capacity region of the discrete memoryless mac was independently derived by ahlswede @xcite and liao @xcite in the early 1970s . in this paper , we are interested in the gaussian version of this problem for which the channel output @xmath1 corresponding to the inputs @xmath2 is @xmath3 where @xmath4 is standard gaussian noise . we assume an average transmission power constraint of @xmath5 corresponding to each transmitter @xmath6 .
the capacity region was derived by cover @xcite and wyner @xcite and is the set of all rate tuples @xmath7 that satisfy @xmath8 for all subsets @xmath9 . for the @xmath10 case , the pentagonal region of rate tuples in is known as the _ cover - wyner _ region and.
Please generate the next two sentences of the article | is illustrated in figure [ fig : cap_reg ] . despite our seemingly complete understanding of fundamental limits of the gaussian mac ,
it is worth highlighting that in the above - mentioned seminal works @xcite , it is assumed that the average error probability tends to zero as the length of the code grows without bound . |
9,781 | Suppose that you have an abstract for a scientific paper: warm absorbers are an important new probe of the central region of active galaxies ( agn ) .
observing and modeling this component provides a wealth of information on the nature of the warm absorber itself , its relation to other components of the active nucleus , and the intrinsic agn x - ray spectral shape .
we briefly review the general properties of dusty warm gas .
for the first time , we then apply such a model to the ir loud quasar .
it was the first to be suggested to host a _ dusty _ warm absorber ( brandt et al .
1996 ) , but has not yet been modeled as such .
.... contribution to the proceedings of ` astrophysical dynamics ' ( evora , april 14 - 16 , 1999 ) ; to appear in ap&ss .
preprint available at http://www.xray.mpe.mpg.de/~skomossa .... .
And you have already written the first three sentences of the full article: so far , warm absorbers revealed their existence mainly in the soft x - ray spectral region by imprinting absorption edges on the x - ray spectra of many agn .
this highly ionized material provides an important new diagnostic tool to investigate the physical conditions in the nuclei of active galaxies .
recently , evidence has accumulated that some warm absorbers contain significant amounts of dust ..
Please generate the next two sentences of the article | this possibility was first suggested by brandt et al .
( 1996 , b96 hereafter ) to explain the lack of excess x - ray _ cold _ absorption despite strong optical reddening of the quasar iras 13349 + 2438 . a point emphasized by komossa & fink ( kofi hereafter , e.g. 1997a , b ) and komossa & bade ( koba ; 1998 ) is the strong influence of the presence of dust on the x - ray absorption spectrum which becomes drastic for high column densities @xmath0 . |
9,782 | Suppose that you have an abstract for a scientific paper: two questions about the solar magnetic field might be answered together once their connection is identified .
the first is important for large scale dynamo theory : what prevents the magnetic backreaction forces from shutting down the dynamo cycle ?
the second question is : what determines the handedness of twist and writhe in magnetized coronal ejecta ?
magnetic helicity conservation is important for answering both questions .
conservation implies that dynamo generation of large scale writhed structures is accompanied by the oppositely signed twist along these structures .
the latter is associated with the backreaction force .
we suggest that coronal mass ejections ( cmes ) simultaneously liberate small scale twist and large scale writhe of opposite sign , helping to prevent the cycle from quenching and enabling a net magnetic flux change in each hemisphere .
observations and helicity spectrum measurements from a numerical simulation of a rising flux ribbon in the presence of rotation support this idea .
we show a new pictorial of dynamo flux generation that includes the backreaction and magnetic helicity conservation by characterizing the field as a 2-d ribbon rather than a 1-d line . * subject headings * : mhd sun : activity sun : magnetic fields mhd turbulence ; stars magnetic fields ; galaxies magnetic fields ; methods .
And you have already written the first three sentences of the full article: the helical magnetic dynamo is the basis for a promising class of mechanisms to explain large scale magnetic fields observed in stars and galaxies @xcite .
the basic `` @xmath0 '' dynamo is the specific version most relevant for strongly sheared rotators ( fig . 1 ) .
interface @xmath0 dynamos ( parker 1993 ; charbonneau & macgregor 1996 ; markiel & thomas 1999 ) include the fact that , unlike for galaxies and disks , the dominant shear layer is beneath the dominant turbulent region ..
Please generate the next two sentences of the article | focusing on the simplest `` @xmath0 '' picture ( fig . 1 ) ,
consider an initially weak toroidal ( = encircling the rotation axis ) loop of the magnetic field embedded in the astrophysical plasma rotator . the magnetic field is coupled to the plasma so the field is carried or stretched in response the plasma motion . |
9,783 | Suppose that you have an abstract for a scientific paper: there is growing evidence that the unconventional spatial inhomogeneities in the doped high - tc superconductors are accompanied by the pairing of electrons , subsequent quantum phase transitions ( qpts ) , and condensation in coherent states .
we show that these superconducting states can be obtained from phase separation instabilities near the quantum critical points .
we examine electron coherent and incoherent pairing instabilities using our results on exact diagonalization in pyramidal and octahedron hubbard - like clusters under variation of chemical potential ( or doping ) , interaction strength , temperature and magnetic field .
we also evaluate the behavior of the energy gap in the vicinity of its sign change as a function of out - of - plane position of the apical oxygen atom , due to vibration of apical atom and variation of inter - site coupling .
these results provide a simple microscopic explanation of ( correlation induced ) supermodulation of the coherent pairing gap observed recently in the scanning tunneling microscopy experiments at atomic scale in @xmath0 .
the existence of possible modulation of local charge density distribution in these materials is also discussed . .
And you have already written the first three sentences of the full article: [ intro ] since the discovery of the high - temperature ( high-@xmath1 ) superconductors in 1986 , there have been many advances in the field of superconductivity due to intense worldwide research efforts .
several sets of ceramic cuprate materials have been synthesized and the transition temperature @xmath1 in some of these has exceeded @xmath2 .
they all share a common quasi - two - dimensional structure and the superconductivity is believed to originate from the electron correlations in the @xmath3 planes . in spite of intensive study of these compounds during the past decade , there is no consensus on a possible mechanism for superconductivity . at the same time , researchers have focused on out - of - plane effects as an explanation in the cuprate superconductors , because all the cuprate families share the same @xmath3 plane , but the maximum @xmath4 varies dramatically from one cuprate family to another @xcite ..
Please generate the next two sentences of the article | this variation is unlikely to be caused by the electronic interactions in the @xmath3 plane , but it is most probably due to different atomic structures between the planes and their indirect effect on the electronic structure in the @xmath3 plane .
recently , it has been argued that the non - planar apical oxygen atoms in the @xmath5 pyramid or @xmath6 octahedron play an important role in the out - of - plane atomic - scale lattice effects in high @xmath7 superconductors ( htscs ) @xcite . |
9,784 | Suppose that you have an abstract for a scientific paper: we study the propagation of electromagnetic waves in the limit of geometrical optics for a class of nearly transparent nonlinear uniaxial metamaterials for which their permittivity tensors present a negative principal component .
their permeability are assumed positive and dependent on the electric field .
we show that light waves experience triple refraction trirefringence . additionally to the ordinary wave ,
two extraordinary waves propagate in such media . .
And you have already written the first three sentences of the full article: electromagnetic waves in a material medium propagate according to maxwell s equations complemented by certain relations linking strengths and induced fields the constitutive relations . depending on the dielectric properties of the medium and also on the presence of applied external fields , a variety of optical effects can be found .
one of wide interest is the birefringence @xcite , occurring when electromagnetic waves propagate in media exhibiting two distinct refractive indexes @xcite in a same wave vector direction .
this effect occurs naturally in some well known crystalline solids , as quartz and sapphire for instance . in nonlinear media , where the dielectric coefficients are field dependent , birefringence could also be induced by the presence of external fields , leading to the known kerr , cotton mouton and magnetoelectric effects @xcite ..
Please generate the next two sentences of the article | birefringence has been widely used in technology of optical devices @xcite and as a powerful experimental technique for investigating properties of physical systems , including biological @xcite and astrophysical ones @xcite , among others .
the phenomenon of triple refraction has been much less investigated . by trirefringence in a given wave vector direction , we mean the existence of three distinct refractive indexes in that direction . in the realm of linear electrodynamics |
9,785 | Suppose that you have an abstract for a scientific paper: we study the entanglement entropy scaling of the xxz chain . while in the critical xy phase of the xxz chain the entanglement entropy scales logarithmically with a coefficient that is determined by the associated conformal field theory , at the ferromagnetic point , however , the system is not conformally invariant yet the entanglement entropy still scales logarithmically albeit with a different coefficient .
we investigate how such an nontrivial scaling at the ferromagnetic point influences the estimation of the central charge @xmath0 in the critical xy phase .
in particular we use the entanglement scaling of the finite or infinite system , as well as the finite - size scaling of the ground state energy to estimate the value of @xmath0 .
in addition , the spin - wave velocity and the scaling dimension are also estimated .
we show that in all methods the evaluations are influenced by the nearby ferromagnetic point and result in crossover behavior .
finally we discuss how to determine whether the central charge estimation is strongly influenced by the crossover behavior and how to properly evaluate the central charge . .
And you have already written the first three sentences of the full article: entanglement plays an important role in distinguishing the nature of quantum versus classical systems .
it is an essential ingredient for quantum computation .
it also connects quantum information theory to the traditional quantum many - body systems , for example , quantum critical phenomena @xcite and topological systems such as fractional quantum hall effects @xcite , topological insulators @xcite and graphene @xcite . in recent developments entanglement.
Please generate the next two sentences of the article | has also been related to numerical methods based on tensor network algorithms , ranging from the density - matrix renormalization group and matrix product state@xcite , to the projected entangled pair states , and variational renormalization group methods @xcite .
one can measure the entanglement of a pure state using bipartite entanglement entropy : consider a pure state @xmath1 of a bipartite total system @xmath2 that consists of the system @xmath3 and the environment @xmath4 . |
9,786 | Suppose that you have an abstract for a scientific paper: the magnetic state of the noncentrosymmetric antiferromagnet cenic@xmath0 has been studied by magnetic susceptibility , heat capacity , muon spin relaxation ( @xmath1sr ) and inelastic neutron scattering ( ins ) measurements .
cenic@xmath0 exhibits three magnetic phase transitions at @xmath2 = 20 k , @xmath3 = 10 k and @xmath4 = 2.5 k. the presence of long range magnetic order below 20 k is confirmed by the observation of oscillations in the @xmath1sr spectra between 10 and 20 k and a sharp increase in the muon depolarization rate .
ins studies reveal two well - defined crystal electric field ( cef ) excitations around 8 and 30 mev .
ins data have been analyzed using a cef model and the wave functions were evaluated .
we also calculated the direction and magnitude of the ground state moment using cef wave functions and compare the results with that proposed from the neutron diffraction .
our cef model correctly predicts that the moments order along the @xmath5axis ( or @xmath6-axis ) and the observed magnetic moment is 0.687(5 ) @xmath7 , which is higher than the moment observed from the neutron diffraction ( 0.25 @xmath7/ce ) .
we attribute the observed reduced moment due to the kondo screening effect . .
And you have already written the first three sentences of the full article: a rich variety of novel phenomena perceptible in ce - based strongly correlated electron systems due to the duality between the localized and the itinerant nature of @xmath8-electrons , such as heavy electron and mixed valence behavior , kondo insulator or semiconductors , unconventional superconductivity , spin and charge density waves , spin and charge gap formation and metal - insulator transition of special recent interest , is the fascinating phenomena associated with magnetic quantum criticality and non - fermi liquid behavior arising from cooperative behavior at a zero temperature phase transition .
@xcite 0.4 cm rnic@xmath0 ( r = rare earth ) compounds crystallize in the noncentrosymmetric ( ncs ) orthorhombic cenic@xmath0 type structure ( space group amm2 ) in which a mirror plane is missing along the @xmath9-axis .
@xcite diverse ground states such as the superconducting , antiferromagnetic ( afm)/ferromagnetic ( fm ) and the charge density - wave ( cdw ) state are reported so far in rnic@xmath0(r = la , ce , pr , sm , gd , tb and er ) , reflecting the competition among different electronic states ..
Please generate the next two sentences of the article | @xcite no structural phase transition has been reported in these compounds , and hence the spin and charge ordering phenomena in rnic@xmath0 compounds are thus native to the ncs crystal structure .
lanic@xmath0 is a superconductor below about 2.7 k. @xcite the absence of an inversion center is believed to give rise to mixed wave pair states ( s - wave singlet and p - wave triplet ) in ncs superconductors . |
9,787 | Suppose that you have an abstract for a scientific paper: a modified f(g ) gravity model with coupling between matter and geometry is proposed , which is described by the product of the lagrange density of the matter and an arbitrary function of the gauss - bonnet term .
the field equations and the equations of motion corresponding to this model show the non - conservation of the energy - momentum tensor , the presence of an extra - force acting on test particles and the non - geodesic motion .
moreover , the energy conditions and the stability criterion at de sitter point in the modified f(g ) gravity models with curvature - matter coupling are derived , which can degenerate to the well - known energy conditions in general relativity . furthermore ,
in order to get some insight on the meaning of these energy conditions , we apply them to the specific models of f(g ) gravity and the corresponding constraints on the models are given .
in addition , the conditions and the candidate for late - time cosmic accelerated expansion in the modified f(g ) gravity are studied by means of conditions of power - law expansion and the equation of state of matter less than @xmath0 . .
And you have already written the first three sentences of the full article: according to recent observational data sets@xcite , our current universe is flat and undergoing a phase of the accelerated expansion which started about five billion years ago . in principle
, this phenomenon can be explained by either dark energy ( see , for instance , ref.@xcite for reviews ) , in which the reason of this phenomenon is due to an exotic component with large negative pressure , or modified theories of gravity@xcite .
unfortunately , up to now a satisfactory answer to the question that what dark energy is and where it came from has not yet to be obtained ..
Please generate the next two sentences of the article | alternative to dark energy , modified theories of gravity is extremely attractive , such as f(r ) gravity ( see , for instance , ref.@xcite for reviews ) , here f(r ) is an arbitrary function of the ricci scalar r. cosmic acceleration can be explained by f(r ) gravity@xcite , and the conditions of viable cosmological models have been derived in @xcite .
a general model of @xmath1 gravity has been proposed in ref.@xcite , which contains a non - minimal coupling between geometry and matter . |
9,788 | Suppose that you have an abstract for a scientific paper: in this paper , the author presents a new tool , called _ the convergence plane _ , that allows to study the real dynamics of iterative methods whose iterations depends on one parameter in an easy and compact way .
this tool can be used , inter alia , to find the elements of a family that have good convergence properties and discard the bad ones or to see how the basins of attraction changes along the elements of the family . to show the applicability of the tool an example of the dynamics of the damped newton s method applied to a cubic polynomial is presented . +
* keywords : * real dynamics , nonlinear equations , the convergence plane , iterative methods , basins of attraction . + +
ngel alberto magren + universidad de la rioja + departamento de matemticas y computacin + 26002 logroo , la rioja , spain + [email protected] + .
And you have already written the first three sentences of the full article: the main aim of the author in this paper is to present a new tool which can make easier the study of the real dynamics of families of iterative methods which depends on a certain parameter or even the study of an iterative method applied to a uniparametric family of polynomials .
this tool can be modified in order to extend , amongst other ones , to methods which needs two approximations as for example , secant - type methods , modified newton s method , etc .
the dynamics of iterative methods used for solving nonlinear equations in complex plane has been studied recently by many authors @xcite ..
Please generate the next two sentences of the article | there exists a belief that real dynamics is included in the complex dynamics but this is not true at all .
for example in the real dynamics one can proof the monotone convergence which does not exist in the complex plane , there exists also asymptotes in the real dynamics but in the complex one that concept has no sense or the point @xmath0 in the complex plane can be studied as another point but in the real line it is not possible . as a consequence |
9,789 | Suppose that you have an abstract for a scientific paper: recent work has suggested the existence of glassy behavior in a ferromagnetic model with a four - spin interaction . motivated by these findings , we have studied the dynamics of this model using monte carlo simulations with particular attention being paid to two - time quantities .
we find that the system shares many features in common with glass forming liquids .
in particular , the model exhibits : ( i ) a very long - lived metastable state , ( ii ) autocorrelation functions that show stretched exponential relaxation , ( iii ) a non - equilibrium timescale that appears to diverge at a well defined temperature , and ( iv ) low temperature aging behaviour characteristic of glasses . 2 .
And you have already written the first three sentences of the full article: many liquids when cooled below the melting temperature do not crystallize . instead , as the temperature is lowered , the relaxation time ( or the viscosity ) increases dramatically , eventually becoming so large that the liquid appears frozen on experimental timescales . for all practical purposes
the system has solidified yet there is no long range order .
the system is said to have become a glass . despite over fifty years of work , a consensus is lacking on a theory of this phenomenon@xcite . even as basic a question as the existence of a genuine thermodynamic glass transition is difficult to decide experimentally . therefore , much work in this field has been numerical ..
Please generate the next two sentences of the article | simulations in the continuum of glassy systems remain difficult , and , despite the substantial progress in this direction@xcite , there are still many unresolved issues . because of these problems it would be useful to have simplified lattice models that behave in some respects like glasses and which do not have quenched disorder . recently , lipowski@xcite and lipowski and johnston@xcite studied such a model by monte carlo simulations and provided evidence of glassy behavior .
the model is defined by the hamiltonian @xmath0 where the spins sit on a cubic lattice and the interactions are between the four spins at the corners of each plaquette . |
9,790 | Suppose that you have an abstract for a scientific paper: the degree of randomness , or partial order , present in two - dimensional supramolecular arrays of isophthalate tetracarboxylic acids is shown to vary due to subtle chemical changes such as the choice of solvent or small differences in molecular dimensions .
this variation may be quantified using an order parameter and reveals a novel phase behaviour including random tiling with varying critical properties as well as ordered phases dominated by either parallel or non - parallel alignment of neighbouring molecules , consistent with long - standing theoretical studies . the balance between order and randomness
is driven by small differences in the intermolecular interaction energies , which we show , using numerical simulations , can be related to the measured order parameter .
significant variations occur even when the energy difference is much less than the thermal energy highlighting the delicate balance between entropic and energetic effects in complex self - assembly processes .
two - dimensional molecular networks provide an attractive and highly flexible route to the formation of surfaces with specific structural arrangements and functionalities @xcite . within the broad range of structures that have been explored ,
random molecular networks have gained considerable attention recently as exemplars of two - dimensional , nonperiodic glassy systems @xcite .
although these systems are of great interest , and represent examples of complex self - assembled sytems , a quantitative measure of the degree of randomness present in a molecular array , which is required for a theoretical understanding of their properties , is not generally available . in this paper
we report a set of supramolecular arrays in which the randomness varies due to small changes in chemical environment or molecular geometry .
we define an order parameter which quantifies these variations and provides a systematic comparison between supramolecular arrays prepared using similar methodologies .
furthermore , we show....
And you have already written the first three sentences of the full article: * chemicals .
* 1,4-diphenyl-1,3-butadiyne-3,3``,5,5''-tetracarboxylic acid ( dpbdtc ) and _ p_-terphenyl-3,5,3``,5''-tetracarboxylic acid ( tptc ) were synthesized in - house , details of their synthesis can be found in the accompanying supplementary material and ref . respectively .
other chemicals used were coronene ( @xmath5695.0% , fluka ) , heptanoic acid ( @xmath5697% , sigma ) , octanoic acid ( @xmath5698% , aldrich ) , and nonanoic acid ( @xmath5695% , fluka ) ..
Please generate the next two sentences of the article | * stm experiments .
* stm images were acquired with an agilent technologies 4500 picoplus stm using a picoscan controller and stm tips formed from mechanically cut ptir ( 80:20 ) wire . |
9,791 | Suppose that you have an abstract for a scientific paper: to study the fluctuations and dynamics in chemical reaction processes , stochastic differential equations based on the rate equation involving chemical concentrations are often adopted .
when the number of molecules is very small , however , the discreteness in the number of molecules can not be neglected since the number of molecules must be an integer .
this discreteness can be important in biochemical reactions , where the total number of molecules is not significantly larger than the number of chemical species . to elucidate the effects of such discreteness , we study autocatalytic reaction systems comprising several chemical species through stochastic particle simulations . the generation of novel states is observed ; it is caused by the extinction of some molecular species due to the discreteness in their number .
we demonstrate that the reaction dynamics are switched by a single molecule , which leads to the reconstruction of the acting network structure .
we also show the strong dependence of the chemical concentrations on the system size , which is caused by transitions to discreteness - induced novel states . .
And you have already written the first three sentences of the full article: in nature , there exist various systems that involve chemical reactions .
some systems are on a geographical scale while others are on a nanoscale , in particular , the biochemical reactions in a cell . to study the dynamics of reaction systems , we often adopt rate equations in order to observe the change in the chemical concentrations . in rate equations , we consider the concentrations to be continuous variables and the rate of each reaction as a function of the concentrations .
in fact , in macroscopic systems , there are a large number of molecules ; therefore , continuous representations are usually applicable.
Please generate the next two sentences of the article | . when the concentration of a certain chemical is low , fluctuations in the reactions or flows can not be negligible .
they are usually treated by employing stochastic differential equations , in which the noise is used as a continuum description of the fluctuations @xcite . |
9,792 | Suppose that you have an abstract for a scientific paper: lensing in a spherically symmetric and static spacetime is considered , based on the lightlike geodesic equation without approximations . after fixing two radius values @xmath0 and @xmath1 ,
lensing for an observation event somewhere at @xmath0 and static light sources distributed at @xmath1 is coded in a lens equation that is explicitly given in terms of integrals over the metric coefficients .
the lens equation relates two angle variables and can be easily plotted if the metric coefficients have been specified ; this allows to visualize in a convenient way all relevant lensing properties , giving image positions , apparent brightnesses , image distortions , etc .
two examples are treated : lensing by a barriola - vilenkin monopole and lensing by an ellis wormhole . .
And you have already written the first three sentences of the full article: theoretical work on gravitational lensing is traditionally done in a quasi - newtonian approximation formalism , see , e.g. , schneider , ehlers and falco @xcite or petters , levine and wambsganss @xcite , which is based , among other things , on the approximative assumptions that the gravitational field is weak and that the bending angles are small . under these assumptions ,
lensing is described in terms of a `` lens equation '' that determines a `` lens map '' from a `` deflector plane '' to a `` source plane '' , thereby relating image positions on the observer s sky to source positions .
although for all practical purposes up to now this formalism has proven to be very successful , there are two motivations for doing gravitational lens theory beyond the quasi - newtonian approximation ..
Please generate the next two sentences of the article | first , from a methodological point of view it is desirable to investigate qualitative features of lensing , such as criteria for multiple imaging or for the formation of einstein rings , in a formalism without approximations , as far as possible , to be sure that these features are not just reflections of the approximations .
second , lensing phenomena where strong gravitational fields and large bending angles are involved are no longer as far away from observability as they have been a few years ago . in particular , the discovery that there is a black hole at the center of our galaxy @xcite , and probably at the center of most galaxies , has brought the matter of lensing in strong gravitational fields with large bending angles closer to practical astrophysical interest . |
9,793 | Suppose that you have an abstract for a scientific paper: recent studies based on unitary chiral perturbation theory ( u@xmath0pt ) found that the low - lying axial vector mesons can be dynamically generated due to the interaction of the pseudoscalar octet of the pion and the vector nonet of the rho .
in particular , two poles in the second riemann sheet have been associated to the nominal @xmath1 resonance . in this talk , we present a recent analysis of the wa3 data on @xmath2 at 63 gev using the u@xmath0pt amplitudes , and show that it is in favor of the existence of two @xmath1 s [ phys . rev .
d 75 , 014017 ( 2007 ) ] .
= 11.6pt .
And you have already written the first three sentences of the full article: the unitary extension of chiral perturbation theory , u@xmath0pt , has been successfully applied to study many meson - baryon and meson - meson interactions .
more recently , it has been used to study the lowest axial vector mesons @xmath3 , @xmath4 , @xmath5 , @xmath6 , @xmath7 , @xmath1 and @xmath8 @xcite .
both works generate most of the low - lying axial vector mesons dynamically ..
Please generate the next two sentences of the article | however , there is a surprising discovery in ref .
@xcite , i.e. , two poles are found in the second riemann sheet in the @xmath9 and @xmath10 channel and both are attributed to the @xmath1 . |
9,794 | Suppose that you have an abstract for a scientific paper: we study the effect of semicore states on the self - energy corrections and electronic energy gaps of silicon , germanium and gaas .
self - energy effects are computed within the gw approach , and electronic states are expanded in a plane - wave basis . for these materials ,
we generate _ ab initio _ pseudopotentials treating as valence states the outermost two shells of atomic orbitals , rather than only the outermost valence shell as in traditional pseudopotential calculations .
the resulting direct and indirect energy gaps are compared with experimental measurements and with previous calculations based on pseudopotential and `` all - electron '' approaches .
our results show that , contrary to recent claims , self - energy effects due to semicore states on the band gaps can be well accounted for in the standard valence - only pseudopotential formalism . .
And you have already written the first three sentences of the full article: since the early applications of the gw method to real materials ( see refs . 1 - 3 and references therein ) , the pseudopotential plane - wave approach has been the method of choice due to its accuracy and technical simplicity .
recent advances in lapw and lmto methodologies have allowed the implementation of `` all - electron '' applications of the gw method.@xcite one common feature of such calculations , using standard level of approximation for the self - energy , is an underestimation of the electronic energy gap compared to experimental measurements , whereas pseudopotential - based calculations show very good agreement with experiment . to explain this inconsistency , it was proposed that the pseudopotential approach does not correctly describe the effect of core orbitals in the self - energy corrections to the energy gaps , resulting in overestimated corrections.@xcite it is thus desirable to elucidate the effect of core orbitals in the quasiparticle band structure , and the preferred procedure is to perform a well converged all - electron calculation and compare its results with similarly converged pseudopotential - based calculations . obviously , numerical precision should not be neglected . in this work ,
we explicitly include semicore orbitals in the pseudopotential plane - wave approach and calculate the quasiparticle energy gap for three semiconductors of technical importance : si , ge and gaas ..
Please generate the next two sentences of the article | the underlying description of the ground - state electronic structure is based on density functional theory in the local density approximation ( dft / lda).@xcite throughout this work , we are careful to converge all results systematically , and the final results are compared to previous pseudopotential results and to recent all - electron calculations .
the paper is organized as follows : we outline the theoretical method in section ii . |
9,795 | Suppose that you have an abstract for a scientific paper: in this paper , we consider a class of multiterminal source coding problems , each subject to distortion constraints computed using a specific , entropy - based , distortion measure .
we provide the achievable rate distortion region for two cases and , in so doing , we demonstrate a relationship between the lossy multiterminal source coding problems with our specific distortion measure and ( 1 ) the canonical slepian - wolf lossless distributed source coding network , and ( 2 ) the ahlswede - krner - wyner source coding with side information problem in which only one of the sources is recovered losslessly . .
And you have already written the first three sentences of the full article: a complete characterization of the achievable rate distortion region for the classical lossy multiterminal source coding problem depicted in fig .
[ fig : mtsc ] has remained an open problem for over three decades .
several special cases have been solved : * the lossless case where @xmath0 ..
Please generate the next two sentences of the article | slepian and wolf solved this case in their seminal work@xcite . * the case where one source is recovered losslessly : i.e. , @xmath1 .
this case corresponds to the source coding with side information problem of ahlswede - krner - wyner @xcite,@xcite . * |
9,796 | Suppose that you have an abstract for a scientific paper: we examine the measured rates for the decays @xmath0 , @xmath1 and @xmath2 in a number of scenarios , in the framework of the heavy quark effective theory .
we attempt to find a scenario in which all of these decays are described by a single set of form factors .
once such a scenario is found , we make predictions for the rare decays @xmath3 .
while we find that many scenarios can provide adequate descriptions of all the data , somewhat surprisingly , we observe that two popular choices of form factors , namely monopolar forms and exponential forms , exhibit some shortcomings , especially when confronted with polarization observables .
we predict @xmath4 and @xmath5 .
we also make predictions for polarization observables in these decays .
= 10000 /#1#1 -0.5em / .
And you have already written the first three sentences of the full article: the decays of heavy hadrons have recently received much attention in the literature @xcite . from the experimental standpoint ,
these decays allow access to some of the fundamental parameters of the standard model , such as the elements of the cabibbo - kobayashi - maskawa ( ckm ) matrix . questions of cp violation , heavy - flavor oscillations and many others have added to this interest . from the theoretical standpoint , these processes , and the heavy hadrons themselves , allow various quark models of qcd , as well effective theories , to be tested . in particular , the heavy quark effective theory ( hqet ) has both been tested by experimental observations , and has played a major role in the extraction of @xmath6 from experimental data @xcite .
much of the success of hqet has been in the treatment of decays from one heavy flavor to another , namely @xmath7 transitions ..
Please generate the next two sentences of the article | the effective theory is more limited in scope when applied to heavy - to - light transitions , such as @xmath8 or @xmath9 .
neverthless , as we will outline in a later section , the scaling behavior of the form factors that describe various weak decays can be deduced @xcite . |
9,797 | Suppose that you have an abstract for a scientific paper: if spacetime contains large compact extra dimensions , the fundamental mass scale of nature , @xmath0 , may be close to the weak scale , allowing gravitational physics to significantly modify electroweak symmetry breaking .
operators of the form @xmath1 and @xmath2 , where @xmath3 and @xmath4 are the @xmath5 and @xmath6 field strengths and @xmath7 is the higgs field , remove the precision electroweak bound on the higgs boson mass for values of @xmath0 in a wide range : @xmath8 . within this framework
, there is no preference between a light higgs boson , a heavy higgs boson , or a non - linearly realized @xmath9 symmetry beneath @xmath0 . if there is a higgs doublet , then operators of the form @xmath10 , where @xmath11 and @xmath12 are the qcd and electromagnetic field strengths , modify the production of the higgs boson by gluon - gluon fusion , and the decay of the higgs boson to @xmath13 , respectively . at run ii of the tevatron collider ,
a @xmath13 signal for extra dimensions will be discovered if @xmath0 is below 2.5 ( 1 ) tev for a higgs boson of mass 100 ( 300 ) gev .
furthermore , such a signal would point to gravitational physics , rather than to new conventional gauge theories at @xmath0 .
the discovery potential of the lhc depends sensitively on whether the gravitational amplitudes interfere constructively or destructively with the standard model amplitudes , and ranges from @xmath14 3 10 ( 2 4 ) tev for a light ( heavy ) higgs boson .
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And you have already written the first three sentences of the full article: the conventional framework for particle physics beyond the standard model ( sm ) assumes that the fundamental mass scale of nature is the planck mass : @xmath15 gev .
it is then natural to ask : why are the masses of the elementary particles so small ? proposed solutions to this hierarchy problem have a common feature : new non - perturbative gauge interactions dynamically generate a much lower scale , @xmath16 , from which electroweak symmetry breaking is generated , and hence all the masses of the known elementary particles .
schematically , this mass hierarchy is @xmath17 in supersymmetric theories , @xmath16 is the scale at which supersymmetry is broken , and the triggering of electroweak symmetry breaking may be mediated , for example , by gravitational - scale physics , or by gauge interactions at much lower energy scales ..
Please generate the next two sentences of the article | alternatively , @xmath16 may be the scale of a new gauge force , technicolor , which forms fermion condensates that directly break @xmath9 .
finally , new strong gauge forces could bind a composite higgs boson . |
9,798 | Suppose that you have an abstract for a scientific paper: two - body bound states such as mesons are described by solutions of the bethe salpeter equation .
we discuss recent results for the pseudoscalar and vector meson masses and leptonic decay constants , ranging from pions up to @xmath0 bound states .
our results are in good agreement with data .
essential in these calculation is a momentum - dependent quark mass function , which evolves from a constituent - quark mass in the infrared region to a current - quark mass in the perturbative region .
in addition to the mass spectrum , we review the electromagnetic form factors of the light mesons . electromagnetic current conservation is manifest and the influence of intermediate vector mesons is incorporated self - consistently .
the results for the pion form factor are in excellent agreement with experiment . .
And you have already written the first three sentences of the full article: the set of dyson
schwinger equations form a poincar covariant framework within which to study hadrons @xcite . in rainbow - ladder truncation , they have been successfully applied to calculate a range of properties of the light pseudoscalar and vector mesons , see ref .
@xcite and references therein ..
Please generate the next two sentences of the article | the dse for the renormalized quark propagator @xmath1 in euclidean space is @xcite @xmath2 where @xmath3 and @xmath4 are the renormalized dressed gluon propagator and quark - gluon vertex , respectively .
the most general solution of eq . |
9,799 | Suppose that you have an abstract for a scientific paper: we study the conductance through a triangular triple quantum dot , which are connected to two noninteracting leads , using the numerical renormalization group ( nrg ) .
it is found that the system shows a variety of kondo effects depending on the filling of the triangle .
the su(4 ) kondo effect occurs at half - filling , and a sharp conductance dip due to a phase lapse appears in the gate - voltage dependence .
furthermore , when four electrons occupy the three sites on average , a local @xmath0 moment , which is caused by the nagaoka mechanism , is induced along the triangle .
the temperature dependence of the entropy and spin susceptibility of the triangle shows that this moment is screened by the conduction electrons via two separate stages at different temperatures . the two - terminal and
four - terminal conductances show a clear difference at the gate voltages , where the su(4 ) or the @xmath0 kondo effects occurring . .
And you have already written the first three sentences of the full article: the kondo effect in quantum dots has been studied in various kinds of systems in recent years , and the triple quantum dots with a triangular configuration is one of the interesting systems @xcite .
specifically , the closed path along the triangle causes a high - spin ground state with the nagaoka mechanism @xcite , and also an su(4 ) kondo effect , depending on the gate voltage . in this report
we study the triangular triple dot connected to two noninteracting leads , and present the results of the scattering phase shifts obtained with the numerical renormalization group ( nrg ) ..
Please generate the next two sentences of the article | we also calculate the temperature dependence of the entropy and spin susceptibility @xcite , which show clearly the two - stage screening process of the high - spin nagaoka state and also the feature of the kondo screening in the su(4 ) case at half - filling .
we consider a three - site hubbard model on a triangle , which is connected to two non - interacting leads on the left ( @xmath1 ) and right ( @xmath2 ) , at @xmath3 and @xmath4 ( @xmath5 ) , respectively , as shown in fig . |
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