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8,900 | Suppose that you have an abstract for a scientific paper: an axial next - nearest - neighbor ising ( annni ) model is studied by using the non - equilibrium relaxation method .
we find that the incommensurate stripe phase between the ordered phase and the paramagnetic phase is negligibly narrow or may vanish in the thermodynamic limit .
the phase transition is the second - order transition if approached from the ordered phase , and it is of the kosterlitz - thouless type if approached from the paramagnetic phase .
both transition temperatures coincide with each other within the numerical errors .
the incommensurate phase which has been observed previously is a paramagnetic phase with a very long correlation length ( typically @xmath0 ) .
we could resolve this phase by treating very large systems ( @xmath1 ) , which is first made possible by employing the present method . .
And you have already written the first three sentences of the full article: of late years , incommensurate ( ic ) stripe structures have been interesting subjects in various physical phenomena . as the typical examples , we may list an alloy @xmath2 which contains heavy rare earth metals , er , tm,@xcite the incommensurate phase of dielectric material such as @xmath3 and @xmath4,@xcite and the stripe structure in @xmath5 planes of oxide superconductors.@xcite in @xmath2 , the longitudinal incommensurate oscillatory phase appears between the paramagnetic phase and the ordered phase .
the aligned holes ( domain walls ) separate antiferromagnetic stripes in @xmath5 planes of oxide superconductors , then the spin and charge are modulated . in such systems ,
cooperative effects of fluctuation and frustration are considered to play important roles ..
Please generate the next two sentences of the article | thus , we sometimes treat them with the axial next - nearest - neighbor ising ( annni ) model as the simplified theoretical model .
for instance , when a uniaxial anisotropy is strong in the dielectric material , the hamiltonian is equivalent to the annni model if we only consider the dipole interactions up to the next - nearest - neighbor distance . |
8,901 | Suppose that you have an abstract for a scientific paper: several radio galaxies are known that show radio morphological signatures that are best interpreted as restarting of nuclear activity after a period of quiescence .
the conditions surrounding the phenomenon of nuclear recurrence are not understood . in this paper
we have attempted to address this question by examining the nuclear fuelling characteristics in a sample of restarting radio galaxies .
we have examined the detection rate for molecular gas in a representative sample of nine restarting radio galaxies , for seven of which we present new upper limits to the molecular gas mass derived from co line observations we made with the iram 30-m telescope .
we derive a low co detection rate for the relatively young restarted radio galaxies suggesting that the cessation of the nuclear activity and its subsequent restarting may be a result of instabilities in the fuelling process rather than a case of depletion of fuel followed by a recent fuel acquisition .
it appears that abundant molecular gas content at the level of few @xmath0 @xmath1 does not necessarily accompany the nuclear restarting phenomenon . for comparison
we also discuss the molecular gas properties of five normal giant radio galaxies , three of which we observed using sest . despite obvious signs of interactions and nuclear dust disks
none of them has been found to host significant quantities of molecular gas .
[ firstpage ] galaxies : active radio lines : galaxies galaxies : ism galaxies : nuclei .
And you have already written the first three sentences of the full article: one of the exciting developments in radio galaxy research in recent years has been the recognition of a restarting of nuclear activity following a quiescent period .
the usual extended twin - lobe radio morphology of radio galaxies are in some cases found to be accompanied by a second pair of lobes sharing the same central radio core ( roettiger et al .
1994 ; subrahmanyan , saripalli & hunstead 1986 ; schoenmakers et al ..
Please generate the next two sentences of the article | the ` double - double ' structures were interpreted by these authors as radio galaxies that were experiencing a second epoch of activity .
detailed studies of some of the more striking examples of this class of radio galaxies ( e.g. lara et al . |
8,902 | Suppose that you have an abstract for a scientific paper: according to the gottesmann - knill theorem the non - gaussian states are necessary component for a nontrivial quantum computation .
we show two efficient and deterministic methods of @xmath0 non - gaussian state generation for a cavity mode using a single trapped ion . both require ion motional state transfer to the cavity field .
the methods are experimentally feasible .
the first is based on the well - known protocol for an ion finite motional superposition state generation .
it allows for an arbitrary good approximation of @xmath0 non - gaussian states .
we give criteria based on the wigner function which quantify the error resulting from the approximation .
the second and novel method enables an exact non - gaussian state generation using one laser pulse only . .
And you have already written the first three sentences of the full article: the gottesmann - knill theorem for continuous variables ( cv ) states that quantum computing based only on components described by one- or two - mode quadratic hamiltonians , gaussian states input , and measurements on canonical variables can be efficiently simulated by a classical computation .
that means , although some of the algorithms are of fundamentally quantum nature , they do not provide any speedup over classical processes @xcite .
it has also been proved that construction of a cv universal quantum computer for transformations that are polynomial in those variables requires cubic or higher non - linear operations @xcite ..
Please generate the next two sentences of the article | therefore , investigation of the non - gaussian transformations and states generation is crucial for a nontrivial quantum computation .
more recently it has been noted that kerr - like nonlinearities , in a variety of systems , enable high precision quantum metrology that would otherwise require entanglement to achieve it @xcite . over the last decade |
8,903 | Suppose that you have an abstract for a scientific paper: we compare the effects of temperature , disorder and parallel magnetic field on the strength of the metallic - like temperature dependence of the resistivity .
we found a similarity between the effects of disorder and parallel field : the parallel field weakens the metallic - like conduction in high mobility samples and make it similar to that for low - mobility samples .
we found a smooth continuous effect of the in - plane field on conduction , without any threshold .
while conduction remains non - activated , the parallel magnetic field restores the same resistivity value as the high temperature does .
this matching sets substantial constraints on the choice of the theoretical models developed to explain the mechanism of the metallic conduction and parallel field magnetoresistance in 2d carrier systems .
we demonstrate that the data for magneto- and temperature dependence of the resistivity of si - mos samples in parallel field may be well described by a simple mechanism of the magnetic field dependent disorder . 2 .
And you have already written the first three sentences of the full article: the apparent metallic - like temperature dependence of the resistivity is observed in various two - dimensional ( 2d ) carrier systems @xcite and remains a focus of a broad interest because it challenges the conventional theory of the metallic conduction .
the effect manifests itself in a strong drop of the resistivity over a limited range of temperatures , @xmath0 , from a high temperature value ( call it ` drude ' value ) @xmath1 to a low temperature one @xmath2 , here @xmath3 is the fermi temperature . upon lowering the temperature further , a strong ` metallic ' drop in @xmath4
was found to cross over to the conventional weak localization type dependence @xcite ..
Please generate the next two sentences of the article | recently , it was demonstrated @xcite that the ` metallic ' drop is not related to quantum interference and in this sense should have a semiclassical origin .
magnetic field applied in the plane of the 2d system causes a dramatic increase in resistivity @xcite . |
8,904 | Suppose that you have an abstract for a scientific paper: we investigate the strong vertices among @xmath0 , nucleon and @xmath1 meson as well as @xmath2 , nucleon and @xmath3 meson in qcd .
in particular , we calculate the strong coupling constants @xmath4 and @xmath5 for different dirac structures entered the calculations . in the case of @xmath6 vertex , the result is compared with the only existing prediction obtained at @xmath7 . # 1#2#3 @xmath8 # 1#2#3 @xmath8 0^*0 5_5 o _ ^0 _ pacs number(s ) : 13.30.-a , 13.30.eg , 11.55.hx .
And you have already written the first three sentences of the full article: the last decade has witnessed to significant experimental progresses on the spectrum and decay products of the hadrons containing heavy quarks .
these progresses have been stimulated the theoretical interests on the spectroscopy of these baryons via various methods ( for some of them see @xcite and references therein ) .
for a better understanding of the heavy flavor physics , it is also necessary to gain deeper insight into the radiative , strong and weak decays of the baryons containing a heavy quark ..
Please generate the next two sentences of the article | for some of the related studies , see @xcite and references therein .
the strong coupling constants are the main ingredients of the strong interactions of the heavy baryons . to improve our understanding on the strong interactions among the heavy baryons and other hadrons and gain knowledge about the nature and structure of the participated particles |
8,905 | Suppose that you have an abstract for a scientific paper: we present new age and distance determinations for the galactic globular clusters m55 and m5 , using the luminosity function method ( jimenez & padoan 1996 , padoan & jimenez 1997 ) .
we find an age of @xmath0 gyr for m55 and @xmath1 gyr for m5 .
this confirms previous results ( jimenez et al .
1996 , sandquist et al . 1996 ) and allows to conclude that * the oldest stars in the universe are not older than 14 gyr*. we also find @xmath2 for m55 , and @xmath3 for m5 .
these values agree with the ones obtained using the tip of the red giant branch ( jimenez et al .
1996 ) and the sub - dwarf fitting method ( sandquist et al . 1996 ) .
epsf globular clusters : general globular clusters : individual ( m5 , m55 ) .
And you have already written the first three sentences of the full article: an accurate determination of the ages and distances of globular clusters ( gcs ) is an important constraint for the age of the universe , and for the theory of galaxy formation . in particular
it is important to compute very accurate relative ages to understand if there is a spread in ages among the galactic gcs or not .
the use of the stellar luminosity function ( lf ) to compute ages of gcs was first proposed by paczynski ( 1984 ) ..
Please generate the next two sentences of the article | later on , jimenez & padoan ( 1996 ) and padoan & jimenez ( 1996 ) developed a method to determine _ the age and the distance of a gc simultaneously _ , using the lf .
the method is described in detail in padoan & jimenez ( 1996 ) , where it is concluded , on the basis of artificial data , that an uncertainty of about 0.6 gyr in the age and 0.06 mag in the distance modulus can be achieved , if the number of stars , in 1 mag - wide luminosity bins , is known with an uncertainty of 3% . in this paper |
8,906 | Suppose that you have an abstract for a scientific paper: we derive simple and explicit expressions for the high frequency spectrum of a classical accretion disc . both stress - free and finite stress
inner boundaries are considered .
a classical accretion disc spectrum with a stress - free inner boundary departs from a wien spectrum at large @xmath0 , scaling as @xmath1 ( as opposed to @xmath2 ) times the usual exponential cut - off .
if there is finite stress at the inner disc boundary , the maximum disc temperature generally occurs at this edge , even at relatively modest values of the stress . in this case
, the high frequency spectrum is proportional to @xmath3 times the exponential cut - off .
if the temperature maximum is a local hot spot , instead of an axisymmetric ring , then an interior maximum produces a @xmath3 prefactor while an edge maximum yields @xmath4 .
because of beaming effects , these latter findings should pertain to a classical relativistic disc .
the asymptotics are in general robust and independent of the detailed temperature profile , provided only that the liberated free energy of differential rotation is dissipated locally , and may prove useful beyond the strict domain of classical disc theory .
as observations continue to improve with time , our findings suggest the possibility of using the high energy spectral component of black hole candidates as a signature prediction of classical theory , as well as an diagnostic of the stress at the inner regions of an accretion disc . .
And you have already written the first three sentences of the full article: well into its fifth decade ( e.g. lynden - bell 1969 , shakura & sunyaev 1973 ) , classical thin disc accretion theory has withstood the test of time reasonably intact .
while it is clear that accretion is considerably more complex than allowed for in classical disc theory ( hereafter cdt ) , there are many examples in which its computed disc spectrum , a superposition of blackbody rings over the surface of the disc , is realised with some fidelity in observations .
even when there are temporal changes in the spectra , there is generally a rather well - defined thin disc state to be found ( e.g. davis et al . 2005 ) ..
Please generate the next two sentences of the article | a detailed theoretical examination of the disc spectrum is both useful and revealing . in its classical and simplest formulation ( lynden - bell 1969 , pringle 1981 , frank , king , & raine 2002 ) ,
the computation of the disc spectrum involves an integral that must in general be evaluated numerically . in this _ letter _ , we show that the integral in question may , however , be performed analytically in the astrophysically relevant limit @xmath5 , where @xmath6 is the photon energy , @xmath7 the boltzmann constant , and @xmath8 the maximum disc temperature . |
8,907 | Suppose that you have an abstract for a scientific paper: we report the discovery of a new soft gamma repeater ( sgr ) , sgr 162741 , and present batse observations of the burst emission and bepposax nfi observations of the probable persistent x - ray counterpart to this sgr .
all but one burst spectrum are well fit by an optically thin thermal bremsstrahlung ( ottb ) model with @xmath0 values between 25 and 35 kev .
the spectrum of the x - ray counterpart , sax j1635.84736 , is similar to that of other persistent sgr x - ray counterparts .
we find weak evidence for a periodic signal at 6.41 s in the light curve for this source . like other sgrs
, this source appears to be associated with a young supernova remnant g337.00.1 . based upon the peak luminosities of bursts observed from this sgr
, we find a lower limit on the dipole magnetic field of the neutron star b@xmath1 gauss . .
And you have already written the first three sentences of the full article: soft gamma repeaters ( sgrs ) are a rare type of stellar object characterized by their transient emission of bursts of hard x - rays and soft @xmath2-rays .
bursts have been detected from three such sources from 1979 ( mazets et al .
1981 ) until early 1998 ; two are in the galactic plane ( sgr 180620 , sgr 1900 + 14 ) and one is in the large magellanic cloud ( sgr 052666 ) ..
Please generate the next two sentences of the article | one of the first sgr bursts detected , the famous 1979 march 5 burst from sgr 052666 ( mazets et al . 1979 ) , provided a wealth of information about these sources ( thompson & duncan 1995 ) .
this flare started with a short initial spike followed by a 3 minute train of coherent 8 s pulsations . |
8,908 | Suppose that you have an abstract for a scientific paper: we study the ground - state properties of one - dimensional mixtures of bosonic and fermionic atoms resonantly coupled to fermionic feshbach molecules . when the particle densities of fermionic atoms and feshbach molecules differ , the system undergoes various depletion transitions between binary and ternary mixtures , as a function of the detuning parameter .
however , when the particle densities of fermionic atoms and feshbach molecules are identical , the molecular conversion and disassociation processes induce a gap in a sector of low - energy excitations , and the remaining system can be described by a two - component tomonaga - luttinger liquid . using a bosonization scheme
, we derive the effective low - energy hamiltonian for the system , which has a similar form as that of the two - chain problem of coupled tomonaga - luttinger liquids . with the help of improved perturbative renormalization group analysis of the latter problem
, we determine the ground - state phase diagram and find that it contains a phase dominated by composite superfluid or pairing correlations between the open and closed resonant channels . .
And you have already written the first three sentences of the full article: the feshbach resonance @xcite , as experimentally realized in ultracold atoms and molecules in optical lattices , has made it possible to investigate the many - body physics of multicomponent quantum degenerate mixtures of fermions and/or bosons with interspecies interactions @xcite .
operationally , a magnetic field near resonance can tune the energy splitting between different hyperfine configurations of atoms , yielding a tunable scattering amplitude with a magnitude that depends on the mismatch of the magnetic moments @xcite . in this
context , theoretical studies have introduced two primary interaction vertices : a short - ranged , one - channel density - density type interaction and a two - channel interaction that couples open - channel atoms to a molecular bound - state ( mb ) particle @xcite . recently , heteronuclear fermionic feshbach molecules composed of bosonic @xmath0na and fermionic @xmath1li @xcite and of bosonic @xmath2rb and fermionic @xmath3k @xcite have been observed experimentally and attracted the attention of theoretical studies @xcite focusing on the competition between the condensed state of unpaired bosons and the degenerate mb particles with an additional fermi surface ..
Please generate the next two sentences of the article | it has been argued that there can be depletion transitions @xcite where one or more of the atomic or molecular species can be exhausted by driving the formation or disassociation of mb particles .
furthermore , if bosons are condensed , the spectrum can be directly diagonalized , yielding mb particles that are dressed by free atomic fermions , which form low - energy quasiparticles in a fermi - liquid theory @xcite . |
8,909 | Suppose that you have an abstract for a scientific paper: results of a ground - based optical monitoring campaign on 3c390.3 in 199495 are presented . the broad - band fluxes ( @xmath0 , @xmath1 , @xmath2 , and @xmath3 ) , the spectrophotometric optical continuum flux @xmath4(5177 ) , and the integrated emission - line fluxes of h@xmath5 , h@xmath6 , h@xmath7 , i5876 hei@xmath8 , and
ii4686 heii@xmath9 all show a nearly monotonic increase with episodes of milder short - term variations superposed .
the amplitude of the continuum variations increases with decreasing wavelength ( 4400 9000 ) .
the optical continuum variations follow the variations in the ultraviolet and x - ray with time delays , measured from the centroids of the cross - correlation functions , typically around 5 days , but with uncertainties also typically around 5 days ; zero time delay between the high - energy and low - energy continuum variations can not be ruled out . the strong optical emission lines h@xmath5 ,
h@xmath6 , h@xmath7 , and i5876 hei@xmath8respond to the high - energy continuum variations with time delays typically about 20 days , with uncertainties of about 8 days . there is some evidence that ii4686 heii@xmath9 responds somewhat more rapidly , with a time delay of around 10 days , but again , the uncertainties are quite large ( @xmath108 days ) . the mean and rms spectra of the h@xmath5 and h@xmath6 line profiles provide indications for the existence of at least three distinct components located at @xmath11 and 0 ^ -1 km
s@xmath12 relative to the line peak .
the emission - line profile variations are largest near line center . .
And you have already written the first three sentences of the full article: intensive multiwavelength monitoring campaigns have shown that variability studies provide an excellent tool to investigate the innermost region of active galactic nuclei ( agns ) .
detailed studies of the continuum and emission - line variations have revealed new insights about the size , structure , and dynamics of the broad - line region ( blr ) in these sources ( see peterson 1993 for a review ) . over the last decade , a number of large space - based and ground - based agn monitoring programs have been undertaken .
our own group , the international agn watch consortium ( alloin et al ..
Please generate the next two sentences of the article | 1994 ) , has undertaken monitoring programs on several seyfert galaxies , including programs on ngc 5548 ( clavel et al .
1991 ; peterson et al . 1991 , 1993 , 1994 ; |
8,910 | Suppose that you have an abstract for a scientific paper: individuals are always limited by some inelastic resources , such as time and energy , which restrict them to dedicate to social interaction and limit their contact capacity .
contact capacity plays an important role in dynamics of social contagions , which so far has eluded theoretical analysis . in this paper , we first propose a non - markovian model to understand the effects of contact capacity on social contagions , in which each individual can only contact and transmit the information to a finite number of neighbors .
we then develop a heterogeneous edge - based compartmental theory for this model , and a remarkable agreement with simulations is obtained . through theory and simulations , we find that enlarging the contact capacity makes the network more fragile to behavior spreading .
interestingly , we find that both the continuous and discontinuous dependence of the final adoption size on the information transmission probability can arise .
and there is a crossover phenomenon between the two types of dependence .
more specifically , the crossover phenomenon can be induced by enlarging the contact capacity only when the degree exponent is above a critical degree exponent , while the the final behavior adoption size always grows continuously for any contact capacity when degree exponent is below the critical degree exponent . *
recent empirical studies of facebook communication networks , scientific cooperation networks and sexual contact networks suggest that individuals activities are limited by the time , funds , energy and other inelastic resources .
thus , individuals exhibit limited contact capacity ( i.e. , individuals can only communicate or interact with a finite number of neighbors during a short time ) in the dynamics of epidemic and behavior .
previous studies have proven that limited contact capacity enlarges the epidemic outbreak threshold and makes the theoretical prediction deviate from simulation results more easily .
unfortunately , a systematical investigation....
And you have already written the first three sentences of the full article: humans are the basic constituents of the society , and every individual can interact with his / her family , friend and peers .
these interactions among individuals can induce some interesting collective behavior , such as , spontaneous formation of a common language or culture , emergence of consensus about a specific issue , and the adoptions of innovation , healthy or microfinance behavior . understanding the mechanisms or regularities behind these collective behavior
has led to a booming subfield of research in complex network science .
Please generate the next two sentences of the article | social contagions , which has attracted much attention in recent years @xcite .
statistical physics approaches were widely used to investigate social contagions . on the one hand |
8,911 | Suppose that you have an abstract for a scientific paper: the possibility of the cdm axino is presented . from the early days of supersymmetry
, axino has been considered as hot dark matter and warm dark matter .
but the cdm axino has been considered quite recently .
it is because the low reheating temperature of the universe is gaining momentum recently from various considerations in particle cosmology .
i present a general introduction on the cdm s , in particular the axino , the calculation on the axino density in the universe , and the constraints imposed on the axino parameters . .
And you have already written the first three sentences of the full article: in this talk , i review the work collaborated with covi _
@xcite on the possibility of the cdm axino .
modern cosmology needs dark matter and dark energy in the universe : @xmath0 ..
Please generate the next two sentences of the article | there are several particle candidates for the cdm : heavy neutrino in the gev range , axion in the @xmath1 ev range , the lightest superpartner(lsp ) in the 100 gev range , wimpzilla in the @xmath2 gev range , axino , and other hypothetical heavy particles .
the particle mass and the interaction strength are provided by particle physics . in the standard big bang cosmology , |
8,912 | Suppose that you have an abstract for a scientific paper: we investigate the problem of structures formation in accretion disc zone , resulting from the tidally interaction in close binary star system .
we aim to examine the area where the incoming flow meets the matter around secondary star and the resulting effects throughout the accretion disc .
the research is based on employment of the fluid dynamics equations in conjunction with numerical simulations leading to the design of graphical models of accretion processes . for the simulation
we propose box - framed sharing schemes .
( i ) the tidal transfer of matter through the inner lagrangian point in close binary stars disturbs the flow in disc s zones and outer disc area .
calculations on the perturbed parameters of density and velocity reveal formation of a thickened zone in the contact area of interacted flows .
it appears to be stable for a number of periods and is unaffected by rotation and dissipation processes .
( ii ) the results also show development of undulations , which grow to vortical patterns in the accretion disc s zone .
it is confirmed that under the influence of tidal wave the conditions of reconfiguring of accretion flow structure are generated .
keywords : accretion ; accretion disks ; hydrodynamics ; waves ; methods : numerical ; ( stars ) : binaries : close ; .
And you have already written the first three sentences of the full article: study of the flow structure in astrophysics is important , because the results could be used both for consideration of the evolution status of binary stars and for the interpretation of observational data .
therefore , when investigating close components , it is necessary to include physical essence of the flow dynamics response to the interaction processes . in the astrophysics of binary stars , one of the most investigated phenomena are vortexes .
vortices and spiral configurations play a key role in the accretion disc dynamics , because they are considered as an efficient mechanism of angular momentum transportation ( baranco & marcus 2005 ) in regions where the magneto - rotational instability ( balbus & hawly 1998 ) does not operate . at present , there are many hydrodynamics studies in finding the way of vortices appear and behave in the flow ..
Please generate the next two sentences of the article | ( 2000 , 2001 ) have shown that vortices are formed by rossby waves instability and moving radially and thus transport mass through the disc .
vortices can be generated by a globally unstable radial entropy gradient ( klahr & bodenheimer 2003 ) that may result in local outward transport of angular momentum . in astrophysics , the problems of structures development have been investigated mainly numerically ( e.g. lithwick 2009 ; godon & livio 1999 ) . |
8,913 | Suppose that you have an abstract for a scientific paper: the space of positive definite symmetric matrices has been studied extensively as a means of understanding dependence in multivariate data along with the accompanying problems in statistical inference .
many books and papers have been written on this subject , and more recently there has been considerable interest in high - dimensional random matrices with particular emphasis on the distribution of certain eigenvalues . with the availability of modern data acquisition capabilities , smoothing or nonparametric techniques
are required that go beyond those applicable only to data arising in euclidean spaces .
accordingly , we present a fourier method of minimax wishart mixture density estimation on the space of positive definite symmetric matrices . , , . .
And you have already written the first three sentences of the full article: the space of positive definite symmetric matrices has been studied extensively in statistics as a means of understanding dependence in multivariate data along with the accompanying problems in statistical inference .
many books and papers , for example , @xcite and @xcite , have been written on this subject , and there has been considerable interest recently in high - dimensional random matrices with particular emphasis on the distribution of certain eigenvalues @xcite and on graphical models @xcite.=1 in this paper we consider the problem of estimating the mixing density of a continuous mixture of wishart distributions .
we construct a nonparametric estimator of that density and obtain minimax rates of convergence for the estimator . throughout this work ,.
Please generate the next two sentences of the article | we adopt , as a guide , results developed for the classical problem of deconvolution density estimation on euclidean spaces ; see , for example , @xcite and @xcite . much of the difficulty with the space of positive definite symmetric matrices is due to the fact that mathematical analysis on the space is technically demanding .
helgason @xcite and terras @xcite provide much insight and technical innovation , however , and we make extensive use of these methods . |
8,914 | Suppose that you have an abstract for a scientific paper: quantum spin models have been studied extensively in one and higher dimensions .
furthermore , these systems have been doped with holes to study @xmath0@xmath1 models of @xmath2 spin-1/2 .
their anyonic counterparts can be built from non - abelian anyons , such as fibonacci anyons described by @xmath3 theories , which are quantum deformations of the @xmath2 algebra .
inspired by the physics of @xmath2 spins , several works have explored ladders of fibonacci anyons and also one - dimensional ( 1d ) @xmath0@xmath1 models . here
we aim to explore the combined effects of extended dimensionality and doping by studying ladders composed of coupled chains of interacting itinerant fibonacci anyons .
we show analytically that in the limit of strong rung couplings these models can be mapped onto effective 1d models .
these effective models can either be gapped models of hole pairs , or gapless models described by @xmath0@xmath1 ( or modified @xmath0@xmath1@xmath4 ) chains of fibonacci anyons , whose spectrum exhibits a fractionalization into charge and anyon degrees of freedom .
the charge degrees of freedom are described by the hardcore boson spectra while the anyon sector is given by a chain of localized interacting anyons . by using exact diagonalizations for two - leg and three - leg ladders ,
we show that indeed the doped ladders show exactly the same behavior as that of @xmath0@xmath1 chains . in the strong ferromagnetic rung limit ,
we can obtain a new model that hosts two different kinds of fibonacci particles - which we denote as the _ heavy _ @xmath5 s and _ light _
@xmath5 s .
these two particle types carry the same ( non - abelian ) topological charge but different ( abelian ) electric charges . once again , we map the two - dimensional ladder onto an effective chain carrying these heavy and light @xmath5 s .
we perform a finite size scaling analysis to show the appearance of gapless modes for certain anyon densities whereas a topological gapped phase is suggested for another density....
And you have already written the first three sentences of the full article: quantum statistics is an important aspect of quantum mechanics and it lays down the rules for identifying different classes of particles . in three dimensions , the exchange of two particles in a quantum system can result in a phase change of either 0 or @xmath6 for the wave function , leading to bosons and fermions .
the scenario is very different in two - dimensions ( 2d ) and it is well known that such quantum systems give rise to anyonic quasiparticle excitations.@xcite these anyons are observed as excitations , localized disturbances of the ground state in systems with topological order .
rich behavior emerges especially for non - abelian anyons , for which the exchange of two anyons is described by a unitary matrix.@xcite models of interacting non - abelian anyons draw motivation from quantum spin models , and in particular the heisenberg model , which has been studied for a wide range of lattices including one - dimension ( 1d ) chains and ladders of @xmath2 spins ..
Please generate the next two sentences of the article | non - abelian anyons can be described as so - called quantum deformations of the usual @xmath2 spins .
formally , they are described by @xmath7 chern - simons theories . |
8,915 | Suppose that you have an abstract for a scientific paper: in this paper , we study a non - linear numerical scheme arising from the implicit time discretization of the baant - thonguthai model for hygro - thermal behavior of concrete at high temperatures . existence and uniqueness of the time - discrete solution in two dimensions
is established using the theory of pseudomonotone operators in banach spaces .
next , the spatial discretization is accomplished by the conforming finite element method .
an illustrative numerical example shows that the model reproduces well the rapid increase of pore pressure in wet concrete due to extreme heating .
such phenomenon is of particular interest for the safety assessment of concrete structures prone to thermally - induced spalling .
heat and moisture transfer phenomena in concrete at high temperatures , rothe method , pseudo - monotone operators , finite element discretization , spalling .
And you have already written the first three sentences of the full article: the hygro - thermal behavior of concrete plays a crucial role in the assessment of the reliability and lifetime of concrete structures .
the heat and mass transfer processes become particularly important at high temperatures , where the increased pressure in pores may lead to catastrophic service failures . since
high - temperature experiments are very expensive , predictive modeling of humidity migration and pore pressure developments can result in significant economic savings ..
Please generate the next two sentences of the article | the first mathematical models of concrete exposed to temperatures exceeding @xmath0c were formulated by baant and thonguthai in @xcite . since then , a considerable effort has been invested into detailed numerical simulations of concrete structures subject to high temperatures . however , much less attention has been given to the qualitative properties of the model , as well as of the related numerical methods .
in particular , the only related work the authors are aware of is due to dalk _ |
8,916 | Suppose that you have an abstract for a scientific paper: we investigate the finite temperature quark anti - quark problem in a compact space @xmath0 by considering static strings in global @xmath1 space with @xmath2 . for high temperatures we work in the black hole metric where two possible solutions show up : the big black hole and the small black hole .
using the ads / cft correspondence , we calculate the quark anti - quark potential ( free energy ) as a function of the distance .
we show that this potential can be intrepeted as confining for the @xmath3 space and deconfining for the big black hole .
we find for the small black hole a confining limit for the potential but this solution is instable following the hawking - page criteria .
our results for the free energy reinforce the witten interpretation of the confinement / deconfinement transition as the dual of the well - known hawking - page transition . .
And you have already written the first three sentences of the full article: confinement of quarks is a very old problem that until now has not been solved . at
low energies perturbative qcd can not be applied because the coupling constant is large .
effective theories and lattice qcd have given important contributions to the understanding of this problem ..
Please generate the next two sentences of the article | a very useful approach to the confinement problem is the study of large n gauge theories because of the possibility of obtaining analytical and numerical results for large ( t hooft ) coupling in a simple way via the ads / cft correspondence @xcite .
this correspondence relates large @xmath4 gauge theories on a @xmath5 dimensional manifold @xmath6 to 10-d string theories on @xmath7 being @xmath6 the boundary of @xmath3 and @xmath8 some compact space . in particular , in the context of ads / cft correspondence witten showed that @xmath9 super yang - mills ( sym ) theory in @xmath10 at strong coupling experiments a confinement / deconfinement transition that corresponds holographically to a gravitational transition between @xmath11 and black hole @xmath11 defined in global coordinates @xcite . |
8,917 | Suppose that you have an abstract for a scientific paper: we present the first high - resolution solar images in the mgiik @xmath0 line .
the images , taken through a @xmath1 broad interference filter , were obtained during the second science flight of sunrise in june 2013 by the sufi instrument .
the mgiik images display structures that look qualitatively very similar to images taken in the core of caiih .
the mgii images exhibit reversed granulation ( or shock waves ) in the internetwork regions of the quiet sun , at intensity contrasts that are similar to those found in caiih .
very prominent in mgii are bright points , both in the quiet sun and in plage regions , particularly near disk center .
these are much brighter than at other wavelengths sampled at similar resolution .
furthermore , mgiik images also show fibril structures associated with plage regions .
again , the fibrils are similar to those seen in caiih images , but tend to be more pronounced , particularly in weak plage . .
And you have already written the first three sentences of the full article: a good knowledge and understanding of the chromosphere is essential for making progress in the questions of chromospheric and coronal heating . studying the chromosphere
is made challenging by the fact that only few spectral lines in the visible and ir spectral ranges accessible from the ground are formed there . of these even fewer sample the middle and upper chromosphere ( hei 10830 , h@xmath2 , caii lines ) .
therefore , it is of considerable interest to explore further avenues ..
Please generate the next two sentences of the article | besides lines in the vacuum ultraviolet , e.g. the ly alpha and neutral carbon and oxygen lines , observed by e.g. sumer @xcite or vault @xcite , another source of information on the chromosphere are the h and k lines of mgii .
these lines are expected to sample a large height range , reaching from the lower to the upper chromosphere , but observations made in these lines are rare due to their inaccessibility from ground . in the mid-1970s , |
8,918 | Suppose that you have an abstract for a scientific paper: eruptive flares are sudden releases of magnetic energy that involve many phenomena , several of which can be explained by the standard 2d flare model and its realizations in three - dimensions .
we analyze a three - dimensional magnetohydrodynamics simulation in the framework of this model that naturally explains the contraction of coronal loops in the proximity of the flare sites , as well as the inflow towards the region above the cusp - shaped loops .
we find that two vorticity arcs located along the flanks of the erupting magnetic flux rope are generated as soon as the eruption begins .
the magnetic arcades above the flux - rope legs are then subjected to expansion , rotation or contraction depending on which part of the vortex - flow advects them .
in addition to the vortices , an inward - directed magnetic pressure gradient exists in the current sheet below the magnetic flux rope .
it results in the formation of a sink that is maintained by reconnection .
we conclude that coronal loop apparent implosions observed during eruptive flares are the result of hydro - magnetic effects related to the generation of vortex- and sink - flows when a flux rope moves in a magnetized environment . .
And you have already written the first three sentences of the full article: solar flares exhibit a multitude of observed dynamic phenomena arising from magnetic energy release ( e.g. , * ? ? ?
* ; * ? ? ?
these phenomena constitute a set of constraints that must be naturally reproduced by any physical model that aims at being generic . in the case of eruptive flares , many observed phenomena have been interpreted in the framework of the cshkp flare model @xcite both in its 2d version and in its realizations in 3d @xcite ..
Please generate the next two sentences of the article | s - shaped x - ray or euv loops seen within so - called sigmoids prior to eruptions ( e.g. * ? ? ?
* ; * ? ? ? |
8,919 | Suppose that you have an abstract for a scientific paper: let @xmath0 and @xmath1 be homogeneous trees of even degree @xmath2 .
a bm group @xmath3 is a torsion free discrete subgroup of @xmath4 which acts freely and transitively on the vertex set of @xmath5
. this article studies dynamical systems associated with bm groups .
a higher rank cuntz - krieger algebra @xmath6 is associated both with a 2-dimensional tiling system and with a boundary action of a bm group @xmath3 .
an explicit expression is given for the k - theory of @xmath6 .
in particular @xmath7 . a complete enumeration of possible bm groups @xmath8 is given for a product homogeneous trees of degree 4 , and the k - groups are computed . .
And you have already written the first three sentences of the full article: the structure of a group which acts freely and cocompactly on a tree is well understood .
any such a group is a finitely generated free group . by way of contrast
, a group which acts in a similar manner on a product of trees can have remarkably subtle properties ..
Please generate the next two sentences of the article | for example , m. burger and s. mozes @xcite have proved rigidity and arithmeticity results analogous to the theorems of margulis for lattices in semisimple lie groups .
this article will consider a discrete subgroup @xmath3 of @xmath4 where @xmath0 , @xmath1 are homogeneous trees of finite degree . |
8,920 | Suppose that you have an abstract for a scientific paper: the energy of a perfectly conducting rectangular cavity is studied by making use of pistons interactions .
the exact solution for a 3d perfectly conducting piston with an arbitrary cross section is being discussed . .
And you have already written the first three sentences of the full article: the casimir effect @xcite was studied in various specific cases and geometries @xcite .
a new geometry that recently attracted attention in the theory of the casimir effect is the piston geometry .
a piston plate is perpendicular to the walls of a semi - infinite cylinder and moves freely inside it , this geometry was first investigated in a @xmath0 dirichlet model @xcite . an exact solution for a perfectly conducting square piston at zero temperature.
Please generate the next two sentences of the article | was found in a @xmath1 model in the electromagnetic and scalar cases @xcite by making use of a geometric optics approach ; the limit of short distances between the piston and the base of a cylinder was found in @xcite for an arbitrary cross section of a piston ; rectangular geometries and finite temperatures were considered in @xcite . in this paper and our previous related papers @xcite we considered a slightly different geometry - two piston plates inside an infinite cylinder , which yielded the same results for rectangular pistons as in the case of a semi - infinite cylinder due to perfectly conducting boundary conditions . in @xcite
an exact solution for arbitrary cross sections and arbitrary distances between piston plates was found at zero and finite temperatures in the electromagnetic @xmath1 case . |
8,921 | Suppose that you have an abstract for a scientific paper: the fuzzy disc is a discretization of the algebra of functions on the two dimensional disc using finite matrices which preserves the action of the rotation group .
we define a @xmath0 scalar field theory on it and analyze numerically for three different limits for the rank of the matrix going to infinity .
the numerical simulations reveal three different phases : uniform and disordered phases already the present in the commutative scalar field theory and a nonuniform ordered phase as a noncommutative effects .
we have computed the transition curves between phases and their scaling .
this is in agreement with studies on the fuzzy sphere , although the speed of convergence for the disc seems to be better .
we have performed also three the limits for the theory in the cases of the theory going to the commutative plane or commutative disc . in this case
the theory behaves differently , showing the intimate relationship between the nonuniform phase and noncommutative geometry .
iccub-12 - 312 * noncommutative field theory : + numerical analysis with the fuzzy disc * fedele lizzi@xmath1 and bernardino spisso@xmath2 + @xmath2_dipartimento di scienze fisiche , universit di napoli _ federico ii _ _ + @xmath3_infn , sezione di napoli _ + _ monte s. angelo , via cintia , 80126 napoli , italy _
+ @xmath4 _ departament de estructura i constituents de la matria , + institut de cincies del cosmos , universitat de barcelona , + barcelona , catalonia , spain _
+ [email protected] , [email protected] 2 cm .
And you have already written the first three sentences of the full article: field theory on noncommutative spaces ( for a review see @xcite ) are a interesting arena to study the properties of noncommutative geometry @xcite .
we will not review here the motivations for a noncommutative geometry . among the applications of noncommutative geometry are fuzzy spaces .
the original fuzzy space is the fuzzy sphere @xcite , but other spaces have been built ( for a review see @xcite ) ..
Please generate the next two sentences of the article | field theory on fuzzy spaces are a way to study field theory on noncommutative spaces on a finite setting .
the fact that the approximation is based on matrices makes them ideal for numerical studies . |
8,922 | Suppose that you have an abstract for a scientific paper: we investigate integer and half - integer filling states ( uniform and unidimensional stripe states respectively ) for graphene using the hartree - fock approximation . for fixed filling factor
, the ratio between the scales of the coulomb interaction and landau level spacing @xmath0 , with @xmath1 the magnetic length , is a field - independent constant .
however , when @xmath2 decreases , the number of filled negative landau levels increases , which surprisingly turns out to decrease the amount of landau level mixing .
the resulting states at fixed filling factor @xmath3 ( for @xmath3 not too big ) have very little landau level mixing even at arbitrarily weak magnetic fields .
thus in the density - field phase diagram , many different phases may persist down to the origin , in contrast to the more standard two dimensional electron gas , in which the origin is surrounded by wigner crystal states .
we demonstrate that the stripe amplitudes scale roughly as @xmath2 , so that the density waves `` evaporate '' continuously as @xmath4 .
tight - binding calculations give the same scaling for stripe amplitude and demonstrate that the effect is not an artifact of the cutoff procedure used in the continuum calculations . .
And you have already written the first three sentences of the full article: graphene , a two - dimensional honeycomb lattice of carbon atoms , has attracted intense attention in the past few years.@xcite its properties bear some similarities with , and some striking differences from , conventional 2d electron gas ( 2deg ) systems found in semiconductor heterostructures .
it is well - known that the latter has a rich phase diagram in the quantum hall regime .
when @xmath5 , the average inter - electron distance measured in units of bohr radius , is not very big , there are integer and fractional quantum hall liquid states , as well as charge density waves ( cdws ) of various forms , including wigner crystals of quasi - electrons , bubbles and stripes at fillings around these liquid states , and analogous particle - hole conjugates of these states @xcite . in high magnetic fields , the particular state is essentially determined by the filling factor @xmath3 , defined as the ratio of the electron density to the density of magnetic flux quanta penetrating the plane . when @xmath5 is increased , these quantum hall phases undergo transitions to wigner crystal ( wc ) states with a single electron per unit cell ..
Please generate the next two sentences of the article | ( for very small @xmath3 , there may also be wigner crystals of composite fermions @xcite . )
if the phase diagram is plotted in the @xmath6 ( density ) - @xmath2 ( magnetic field ) plane , away from the origin , there is a fan of quantum hall phases , but the origin is expected to be completely surrounded by wigner crystal states @xcite [ see fig . |
8,923 | Suppose that you have an abstract for a scientific paper: we show that an ordinary semiconducting thin film with spin - orbit coupling can , under appropriate circumstances , be in a quantum topologically ordered state supporting exotic majorana excitations which follow non - abelian statistics .
the key to the quantum topological order is the coexistence of spin - orbit coupling with proximity - induced @xmath0-wave superconductivity and an externally - induced zeeman coupling of the spins . for the zeeman coupling below a critical value ,
the system is a non - topological ( proximity - induced ) @xmath0-wave superconductor .
however , for a range of zeeman coupling above the critical value , the lowest energy excited state inside a vortex is a zero - energy majorana fermion state .
the system , thus , has entered into a non - abelian @xmath0-wave superconducting state via a topological quantum phase transition ( tqpt ) tuned by the zeeman coupling . in the topological phase ,
since the time reversal symmetry is explicitly broken by the zeeman term in the hamiltonian , the edge of the film constitutes a _ chiral _ majorana wire . just like the @xmath0-wave superconductivity
, the zeeman coupling can also be proximity - induced in the film by an adjacent magnetic insulator .
we show this by an explicit model tight - binding calculation for both types of proximity effects in the heterostructure geometry . here
we show that the same tqpt can be accessed by varying the interface transparency between the film and the superconductor . for the transparency below ( above ) a critical value , the system is a topological ( regular ) @xmath0-wave superconductor . in the one - dimensional version of the same structure and for the zeeman coupling above the critical value , there are localized majorana zero - energy modes at the two ends of a semiconducting quantum nanowire . in this case , the zeeman coupling can be induced more easily by an external magnetic field parallel to the wire , obviating the need for a magnetic insulator .
we show that , despite the....
And you have already written the first three sentences of the full article: particle statistics of a collection of indistinguishable particles is a genuinely quantum mechanical concept without any classical analog . in spatial dimensions three and above ,
pairwise interchange of particle coordinates in a many - body system is equivalent to a simple permutation of the coordinates .
consequently , each interchange has the effect of either a change of sign ( fermion ) or no change at all ( boson ) on the many - body quantum wave function . in @xmath1 dimensions.
Please generate the next two sentences of the article | , however , exchanges and permutations are not necessarily equivalent .
@xcite in this case , under simple interchange of the particle coordinates , the corresponding space - time trajectories can form non - trivial braids in the @xmath1-dimensional space - time . |
8,924 | Suppose that you have an abstract for a scientific paper: following our recent study [ p.yu .
moshin , a.a .
reshetnyak , nucl . phys .
b 888 ( 2014 ) 92 ] , we discuss the notion of finite brst - antibrst transformations , with a doublet @xmath0 , @xmath1 , of anticommuting ( both global and field - dependent ) grassmann parameters .
it turns out that the global finite brst - antibrst transformations form a 2-parametric abelian supergroup .
we find an explicit jacobian corresponding to this change of variables in the theories with a gauge group .
special field - dependent brst - antibrst transformations for the yang mills path integral with @xmath2-potential ( functionally - dependent ) parameters @xmath3 generated by a finite even - valued functional @xmath4 and the anticommuting generators @xmath2 of brst - antibrst transformations , amount to a precise change of the gauge - fixing functional .
this proves the independence of the vacuum functional under such brst - antibrst transformations and leads to the presence of modified ward identities .
the form of transformation parameters that induces a change of the gauge in the path integral is found and is exactly evaluated for connecting two arbitrary @xmath5-like gauges .
the finite field - dependent brst - antibrst transformations are used to generalize the gribov horizon functional @xmath6 , in the landau gauge of the brst - antibrst setting in the gribov zwanziger model , and to find @xmath7 corresponding to general @xmath8-like gauges in the form compatible with a gauge - independent @xmath9-matrix . 2 .
And you have already written the first three sentences of the full article: the special supersymmetries known as brst symmetry @xcite and brst - antibrst symmetry @xcite provide a basis of the modern quantization methods for gauge theories @xcite .
these symmetries feature the presence of a grassmann - odd parameter @xmath10 and two grassmann - odd parameters @xmath11 , respectively .
the latter parameters in the @xmath12-covariant schemes of generalized hamiltonian @xcite and lagrangian @xcite quantization ( see @xcite as well ) @xmath13 form an @xmath14-doublet ..
Please generate the next two sentences of the article | these infinitesimal odd - valued parameters may be regarded both as constants and field - dependent functionals , used , respectively , to derive the ward identities and to establish the gauge - independence of the partition function in the path integral approach . in @xcite ,
the brst transformations with a finite field - dependent parameter ( ffdbrst ) in the gauge theories with a gauge group , i.e. , yang mills ( ym ) theories , whose quantum action is constructed by the faddeev |
8,925 | Suppose that you have an abstract for a scientific paper: properties of hot gas outflows from galaxies are generally measured from associated x - ray line emission assuming that it represents atomic transitions in thermally excited hot gas .
x - ray line emission , however , can also arise from the charge exchange between highly ionised ions and neutral species .
the k@xmath0 triplet of he - like ions can be used as a powerful diagnostic , because the charge exchange x - ray emission ( cxe ) favours the inter - combination and forbidden lines , while the thermal emission favours the resonance line .
we analyse the triplet of a sample of nine nearby star - forming galaxies observed by the reflection grating spectrometers . for most galaxies ,
the forbidden lines are comparable to or stronger than the resonance lines , which is in contrast to the thermal prediction . for ngc 253 , m51 , m83 , m61 ,
ngc 4631 , and the antennae galaxy , the observed line ratios are consistent with the ratio of the cxe ; for m94 and ngc 2903 , the observed ratios indicate multiple origins ; for m82 , different regions show different line ratios , also indicating multiple origins .
we discuss other possible mechanisms that can produce a relatively strong forbidden line , such as a collisional non - equilibrium - ionization recombining / ionizing plasma , which are not favoured .
these results suggest that the cxe may be a common process and contribute a significant fraction of the soft x - ray line emission for galaxies with massive star formation . atomic processes plasmas
ism : jets and outflows ism : abundances galaxies : starburst galaxies : individual : ( m82 , ngc 253 , m51 , m61 , m83 , m94 , ngc 2903 , ngc 4631 , the antennae ) x - rays : galaxies .
And you have already written the first three sentences of the full article: galaxies with massive star formation are the primary source that ejects metals into galactic halos and the intergalactic medium .
the properties of outflows driven by sn explosions and stellar winds are fundamental to the understanding of feedback processes of galaxies . in previous studies , the energy and metals of outflows
are generally inferred from fitting observed spectra with thermal models ..
Please generate the next two sentences of the article | the x - ray line emission , however , can arise not only from hot plasma , but also from its interaction with neutral cool gas .
for example , highly ionised ions in the solar wind can readily pick up electrons from neutral species of a comet . |
8,926 | Suppose that you have an abstract for a scientific paper: the discovery by marcy et al .
( 2001 ) of two planets in 2:1 orbital resonance about the star gj@xmath0876 has been supplemented by a dynamical fit to the data by laughlin & chambers ( 2001 ) which places the planets in coplanar orbits deep in three resonances at the 2:1 mean - motion commensurability .
the selection of this almost singular state by the dynamical fit means that the resonances are almost certainly real , and with the small amplitudes of libration of the resonance variables , indefinitely stable .
several unusual properties of the 2:1 resonances are revealed by the gj@xmath0876system .
the libration of both lowest order mean - motion resonance variables and the secular resonance variable , @xmath1 , @xmath2 , and @xmath3 , about @xmath4 ( where @xmath5 are the mean longitudes of the inner and outer planet and @xmath6 are the longitudes of periapse ) differs from the familiar geometry of the io - europa pair , where @xmath7 and @xmath8 librate about @xmath9 . by considering the condition that @xmath10 for stable simultaneous librations of @xmath11 and @xmath7 , we show that the gj@xmath0876 geometry results because of the large orbital eccentricities @xmath12 , whereas the very small eccentricities in the io - europa system lead to the latter s geometry .
surprisingly , the gj@xmath0876 configuration , with @xmath11 , @xmath7 , and @xmath8 all librating , remains stable for @xmath13 up to 0.86 and for amplitude of libration of @xmath11 approaching @xmath14 with the current eccentricities further supporting the indefinite stability of the existing system .
any process that drives originally widely separated orbits toward each other could result in capture into the observed resonances at the 2:1 commensurability .
we find that forced inward migration of the outer planet of the gj@xmath0876system results in certain capture into the observed resonances if initially @xmath15 and @xmath16 and the migration rate @xmath17 .
larger eccentricities lead to likely capture into....
And you have already written the first three sentences of the full article: marcy et al . ( 2001 ) have discovered two planets about the nearby m dwarf star gj@xmath0876 .
a preliminary fit of the stellar radial velocity ( rv ) variations due to two unperturbed kepler orbits implies that the orbital periods of the two planets are nearly in the ratio 2:1 .
this resonance is an analog to the orbital resonances among the satellites of jupiter and saturn ( e.g. , peale 1999 ) , but it is the first to be discovered among extrasolar planetary systems ..
Please generate the next two sentences of the article | table [ table1 ] shows the system parameters from the marcy et al .
analysis based on data taken at both the keck and lick observatories and an adopted stellar mass of @xmath26 . |
8,927 | Suppose that you have an abstract for a scientific paper: adoption of innovations , products or online services is commonly interpreted as a spreading process driven to large extent by social influence and conditioned by the needs and capacities of individuals .
to model this process one usually introduces behavioural threshold mechanisms , which can give rise to the evolution of global cascades if the system satisfies a set of conditions .
however , these models do not address temporal aspects of the emerging cascades , which in real systems may evolve through various pathways ranging from slow to rapid patterns .
here we fill this gap through the analysis and modelling of product adoption in the world s largest voice over internet service , the social network of skype .
we provide empirical evidence about the heterogeneous distribution of fractional behavioural thresholds , which appears to be independent of the degree of adopting egos .
we show that the structure of real - world adoption clusters is radically different from previous theoretical expectations , since vulnerable adoptions induced by a single adopting neighbour appear to be important only locally , while spontaneous adopters arriving at a constant rate and the involvement of unconcerned individuals govern the global emergence of social spreading .
* keywords : * cascading behaviour , social spreading phenomena , complex contagion , adoption thresholds .
And you have already written the first three sentences of the full article: spreading of opinions , frauds , behavioural patterns , and product adoptions are all examples of social contagion phenomena where collective patterns emerge due to correlated decisions of a large number of individuals . although these choices are personal , they are not independent but potentially driven by several processes such as social influence @xcite , homophily @xcite , and information arriving from external sources like news or mass media @xcite .
social contagion evolves over networks of interconnected individuals , where links associated with social ties transfer influence between peers @xcite .
several earlier studies aimed to identify the dominant mechanisms at play in social contagion processes @xcite ..
Please generate the next two sentences of the article | one key element , termed behavioural threshold by granovetter @xcite , is defined as _
`` the number or proportion of others who must make one decision before a given actor does so''_. following this idea various network models have been introduced @xcite to understand the threshold - driven spreading , commonly known as _ complex contagion _ @xcite . |
8,928 | Suppose that you have an abstract for a scientific paper: explicit 2-d axisymmetric solutions are found to the hydrostatic equilibrium , energy balance , and photon diffusion equations within obscuring tori around active galactic nuclei .
these solutions demonstrate that infrared radiation pressure can support geometrically thick structures in agn environments subject to certain constraints : the bolometric luminosity must be roughly @xmath0@xmath1 the eddington luminosity ; and the compton optical depth of matter in the equatorial plane should be @xmath2 , with a tolerance of about an order of magnitude up or down .
both of these constraints are at least roughly consistent with observations .
in addition , angular momentum must be redistributed so that the fractional rotational support against gravity rises from the inner edge of the torus to the outer in a manner specific to the detailed shape of the gravitational potential .
this model also predicts that the column densities observed in obscured agn should range from @xmath3 to @xmath4 @xmath5 . .
And you have already written the first three sentences of the full article: geometrically and optically thick belts of matter can be seen around many active galactic nuclei ( antonucci 1993 ) . although the evidence is best for nearby seyfert galaxies ( e.g. , the direct detection by jaffe et al .
2004 of the torus in ngc 1068 ) , there is also strong indirect evidence that this picture applies to radio galaxies ( barthel 1989 , di serego alighieri et al .
1994 ) and quasars ( e.g. , the spectropolarimetry presented in zakamska et al ..
Please generate the next two sentences of the article | the ratio of observed numbers of obscured agn to unobscured gives a measure of the fraction of opaque solid angle ; it is generally @xmath2 ( hao et al . 2005 ) .
x - ray column densities to obscured nuclei range from @xmath3 @xmath5 to in excess of @xmath6 @xmath5 ( risaliti et al . 1999 , |
8,929 | Suppose that you have an abstract for a scientific paper: the spin and layer ( pseudospin ) degrees of freedom are entangled coherently in the canted antiferromagnetic phase of the bilayer quantum hall system at the filling factor @xmath0 .
there emerges a complex goldstone mode describing such a combined degree of freedom . in the zero tunneling - interaction limit ( @xmath1 )
, its phase field provokes a supercurrent carrying both spin and charge within each layer .
the hall resistance is predicted to become anomalous precisely as in the @xmath2 bilayer system in the counterflow and drag experiments .
furthermore , it is shown that the total current flowing in the bilayer system is a supercurrent carrying solely spins in the counterflow geometry .
it is intriguing that all these phenomena occur only in imbalanced bilayer systems . .
And you have already written the first three sentences of the full article: physics of the bilayer quantum hall ( qh ) system is enormously rich owing to the intralayer and interlayer phase coherence controlled by the interplay between the spin and the layer ( pseudospin ) degrees of freedom@xcite . at the filling factor @xmath2 there arises a unique phase , the spin - ferromagnet and pseudospin - ferromagnet phase , which has well been studied both theoretically and experimentally .
one of the most intriguing phenomena is the josephson - like tunneling between the two layers predicted in refs.@xcite , whose first experimental indication was obtained in ref.@xcite .
other examples are the anomalous behavior of the hall resistance reported in counterflow experiments@xcite and in drag experiments@xcite ..
Please generate the next two sentences of the article | they are triggered by the supercurrent within each layer@xcite .
quite recently , careful experiments @xcite were performed to explore the condition for the tunneling current to be dissipationless . |
8,930 | Suppose that you have an abstract for a scientific paper: the improved quantum molecular dynamics model is further developed by introducing new parameters in interaction potential energy functional based on skyrme interaction of skm@xmath0 and sly series .
the properties of ground states of selected nuclei can be reproduced very well .
the coulomb barriers for a series of reaction systems are studied and compared with the results of the proximity potential .
the fusion excitation functions for a series of fusion reactions are calculated and the results are in good agreement with experimental data .
pacs numbers : 25.70.-z , 24.10.-i * i. introduction * recently , the study of the mechanism for heavy - ion fusion reactions at energies near the coulomb barrier , especially , the mechanism for the enhancement of fusion cross sections for neutron - rich systems has attracted a lot of attention .
the knowledge of the mechanism of the enhancement of fusion cross sections for heavy and neutron - rich systems is useful in the synthesis of superheavy elements . in heavy - ion fusion reactions ,
the excitation and deformation of projectile and target , neck formation and nucleon transfer strongly influence the dynamics of fusion processes .
these effects are more pronounced at near and below the fusion barrier . for heavy systems , in order to consider these effects a very large number of degrees of freedom of motion is involved and the situation becomes very complicated .
thus one will meet great difficulty by macroscopic dynamics models@xcite in which only few degrees of freedom of motion are included .
the difficulty is also encountered by the fusion coupled channel model@xcite for it is quite difficult even impossible to include such a large number of possible channels in practical calculations .
therefore , it is highly requisite to develop a microscopic dynamical model suitable for studying heavy ion fusion reactions by which one can consistently take account of the dynamical deformation , particle transfer , isospin and mass asymmetry....
And you have already written the first three sentences of the full article: this work is supported by national natural science foundation of china under grant nos . 10235030 , 10235020 , 10175093 , 10175089 and major state basic research development program under contract , no .
g20000774 . `
fig.1 ` : : the time evolution of binding energies and root - mean - square charge radii for @xmath46zr and @xmath51pb calculated by the imqmd - ii model with parameter set of iq1 . `.
Please generate the next two sentences of the article | fig.2 ` : : the static coulomb barriers of @xmath49ca+@xmath48ca , @xmath49ca+@xmath46zr , @xmath50o+@xmath50o and @xmath50o+@xmath51pb .
the solid and dashed curves denote the results of imqmd - ii with parameters of iq1 and those of proximity potential , respectively . ` fig.3 ` : : the static coulomb barriers of @xmath60i+@xmath60i , @xmath61cr+@xmath51pb , @xmath62s+@xmath63th and @xmath64c+@xmath65fm . |
8,931 | Suppose that you have an abstract for a scientific paper: we present a review on the mathematical methods used to theoretically study classical propagation and quantum transport in arrays of coupled photonic waveguides .
we focus on analysing two types of binary photonic lattices where self - energies or couplings are alternated . for didactic reasons
, we split the analysis in classical propagation and quantum transport but all methods can be implemented , _ mutatis mutandis _ , in any given case . on the classical side , we use coupled mode theory and present an operator approach to floquet - bloch theory in order to study the propagation of a classical electromagnetic field in two particular infinite binary lattices . on the quantum side ,
we study the transport of photons in equivalent finite and infinite binary lattices by couple mode theory and linear algebra methods involving orthogonal polynomials .
curiously the dynamics of finite size binary lattices can be expressed as roots and functions of fibonacci polynomials . .
And you have already written the first three sentences of the full article: the analogy between linear lattices and the atom - field interaction @xcite or ion - laser interactions @xcite has been a fundamental step for the emulation , via classical interactions , of quantum mechanical systems .
this is important due to both pure scientific interest and possible applications to quantum computing . in the latter ,
the properties of classical systems have been used to realize quantum computational operations by quantum - like systems and , in particular , it has been show how a controlled - not gate may be generated in nonhomogeneous optical fibers @xcite . at the fundamental level , _.
Please generate the next two sentences of the article | e.g. _ , it has been possible to the emulate the most basic atom - field interaction , the jaynes - cummings model , theoretically @xcite and experimentally @xcite with arrays of photonic waveguides and , just to give another example , it has been proposed to model non - linear coherent states @xcite in waveguide arrays @xcite ; linear coherent states have also been modelled in linear arrays of photonic waveguides @xcite . in what follows
we will take advantage of the simplest composite array of waveguides , _ |
8,932 | Suppose that you have an abstract for a scientific paper: we consider three types of subdiffusion models , namely single - term , multi - term and distributed order fractional diffusion equations , for which the maximum - principle holds and which , in particular , preserve nonnegativity .
hence the solution is nonnegative for nonnegative initial data .
following earlier work on the heat equation , our purpose is to study whether this property is inherited by certain spatially semidiscrete and fully discrete piecewise linear finite element methods , including the standard galerkin method , the lumped mass method and the finite volume element method .
it is shown that , as for the heat equation , when the mass matrix is nondiagonal , nonnegativity is not preserved for small time or time - step , but may reappear after a positivity threshold .
for the lumped mass method nonnegativity is preserved if and only if the triangulation in the finite element space is of delaunay type .
numerical experiments illustrate and complement the theoretical results .
+ * keywords * : subdiffusion , finite element method , nonnegativity preservation , caputo derivative # 1h^#1 ( ) .
And you have already written the first three sentences of the full article: in this work we consider the numerical analysis of mathematical models arising in subdiffusion .
one simple example is the single - term subdiffusion , for which the governing equation is given by @xmath0 under the initial - boundary conditions @xmath1 where @xmath2 is a bounded domain in @xmath3 which for simplicity we assume to be polygonal , and where @xmath4 is a given function on @xmath2 . here
@xmath5 denotes the caputo fractional derivative of order @xmath6 with respect to @xmath7 , defined by the convolution ( see @xcite ) @xmath8 where @xmath9 is the gamma function . by continuity.
Please generate the next two sentences of the article | we may include the standard heat equation for @xmath10 .
the fractional derivative is often used to describe anomalous diffusion , in which the mean square variance grows sublinearly with time @xmath7 , at a rate slower than that in a gaussian process . |
8,933 | Suppose that you have an abstract for a scientific paper: we study a model for quantum lightcone fluctuations in which vacuum fluctuations of the electric field and of the squared electric field in a nonlinear dielectric material produce variations in the flight times of probe pulses .
when this material has a non - zero third order polarizability , the flight time variations arise from squared electric field fluctuations , and are analogous to effects expected when the stress tensor of a quantized field drives passive spacetime geometry fluctuations .
we also discuss the dependence of the squared electric field fluctuations upon the geometry of the material , which in turn determines a sampling function for averaging the squared electric field along the path of the pulse .
this allows us to estimate the probability of especially large fluctuations , which is a measure of the probability distribution for quantum stress tensor fluctuations . .
And you have already written the first three sentences of the full article: light propagation in a nonlinear dielectric may be used to model various subtle effects involving quantum theory and gravity .
these include lightcone fluctuations @xcite and the effects of quantum stress tensor expectation values in semiclassical gravity @xcite .
a fluctuating electric field in a nonlinear material causes fluctuations of the effective speed of light of probe pulses , and is analogous to the effects of spacetime geometry fluctuations on light propagation ..
Please generate the next two sentences of the article | this analogy was developed in ref .
@xcite , where the source of the fluctuations was a squeezed state of the electromagnetic field , and in ref . |
8,934 | Suppose that you have an abstract for a scientific paper: the calculations presented here reveal that an electron probe carrying orbital angular momentum is just a particular case of a wider class of electron beams that can be used to measure electron magnetic circular dichroism ( emcd ) with atomic resolution .
it is possible to obtain an emcd signal with atomic resolution by simply breaking the symmetry of the electron probe phase distribution using the aberration - corrected optics of an scanning transmission electron microscope .
the required phase distribution of the probe depends on the magnetic symmetry and crystal structure of the sample .
the calculations indicate that emcd signals utilizing the phase of the electron probe are as strong as those obtained by nanodiffraction methods .
development of quantitative magnetic characterization techniques goes hand - in - hand with progress in nano - technology .
a terabit per square inch recording density @xcite means that the area available for one bit is not larger than a square of size @xmath0 nm@xmath1 , assuming bits arranged laterally .
this pushes demands for magnetic measurements down to few nm scale @xcite , approaching atomic resolution .
an attractive option to measure magnetism at such high spatial resolutions is an experimental technique based on electron magnetic circular dichroism @xcite ( emcd ) .
particularly , a great promise came recently from utilizing electron vortex beams @xcite ( evbs ) within an electron microscope .
with evbs it should be possible to measure emcd in the direction of the transmitted beam @xcite , which brings a substantial increase in signal to noise ratio compared to intrinsic emcd measured in between bragg spots @xcite .
however , obtaining isolated atomic - size evbs that can be used for emcd measurements have not yet been possible , although different electron optical setups have been proposed @xcite . in this letter , we show how emcd signals can be measured with atomic resolution in the electron microscope at the transmitted beam without the....
And you have already written the first three sentences of the full article: the double - differential scattering cross - section per scattering center ( assuming @xmath89 atoms in the sample ) can be written as @xmath90 where @xmath91 are the initial and final states of the crystal with energies @xmath92 , and @xmath93 is the coulomb interaction potential between the nuclei and electrons of the beam and sample .
the delta - function selects the transitions with energy - difference equal to energy - loss @xmath94 . because of the form of the initial state of the probe wavefunction @xmath95 + \nonumber \\ & + & \sum_{\mathbf{k } \in \omega_2 } ce^{i\phi_\mathbf{k+g}}e^{i(\mathbf{k+g})\cdot\mathbf{r } } \left [ 1 + i t_\mathbf{g } e^{i\mathbf{g}\cdot\mathbf{r } } \right],\end{aligned}\ ] ] the double - differential scattering cross - section contains quite a number of terms and following an explicit derivation for all of them is too lengthy and cumbersome .
however , the derivation follows the same pattern for all terms . therefore we illustrate it on a particular cross - term from the initial probe wave - function : a cross - term between @xmath96 and @xmath97 for @xmath98 . essentially we will perform a similar procedure as a textbook derivation of inelastic electron scattering cross - section of a plane wave on an atom ( see , e.g. , sakurai s _ modern quantum mechanics _.
Please generate the next two sentences of the article | @xcite ) into another plane - wave @xmath99 : @xmath100 where we introduced momentum transfer vectors @xmath28 and @xmath101 , which carry on the @xmath102-dependences .
the crystal wavefunctions are denoted @xmath103 for the initial and final state , respectively . |
8,935 | Suppose that you have an abstract for a scientific paper: the nonlinear rheology of a soft glassy material is captured by its constitutive relation , shear stress vs shear rate , which is most generally obtained by sweeping up or down the shear rate over a finite temporal window . for a huge amount of complex fluids ,
the up and down sweeps do not superimpose and define a rheological hysteresis loop . by means of extensive rheometry
coupled to time - resolved velocimetry , we unravel the local scenario involved in rheological hysteresis for various types of well - studied soft materials .
we introduce two observables that quantify the hysteresis in macroscopic rheology and local velocimetry respectively , as a function of the sweep rate @xmath0 .
strikingly , both observables present a robust maximum with @xmath1 , which defines a single material - dependent timescale that grows continuously from vanishingly small values in simple yield stress fluids to large values for strongly time - dependent materials . in line with recent theoretical arguments , these experimental results hint at a universal timescale - based framework for soft glassy materials , where inhomogeneous flows characterized by shear bands and/or pluglike flow play a central role .
when submitted to external stress , soft glassy materials such as colloidal gels , clay suspensions , concentrated emulsions , and foams , display a fascinating variety of behaviors because the applied strain may disrupt and rearrange the microstructure over a wide range of spatial and temporal scales leading to heterogeneous flow properties @xcite . for more than a decade ,
flow dynamics have been probed by combining standard rheology , e.g. through the determination of the `` constitutive relation '' between the shear stress @xmath2 and the shear rate @xmath3 , and local structural or velocity measurements @xcite .
while much progress has been made on _ steady - state _ local flow properties @xcite , _ transient _ regimes upon shear start - up have been addressed only recently @xcite .
still , in....
And you have already written the first three sentences of the full article: * rheological hysteresis + in soft glassy materials * five movies are provided as supplemental material to show the full data sets corresponding to figs . 1 and 2 in the main text .
the files names indicate the system under investigation ( laponite suspension or carbopol microgel ) and the value of the waiting time per point @xmath1 .
velocity profiles are shown only for @xmath54 s@xmath10 due to the limitation in the ultrasonic pulse repetition frequency to 20 khz , which sets an upper bound on the measurable velocities @xcite ..
Please generate the next two sentences of the article | at very small shear rates noise becomes too large for velocities to remain reliable .
indeed , the amount of velocity data recorded at each shear - rate step of fixed duration @xmath1 increases with @xmath3 @xcite . therefore , at small @xmath3 , the lower statistics result in significant noise in the velocity profiles . in the movies , the data corresponding to the downward ( upward resp . |
8,936 | Suppose that you have an abstract for a scientific paper: let @xmath0 be an odd prime . in this paper we provide a construction which gives four non - schurian association schemes for every @xmath1 and two for @xmath2 .
this construction is explained using incidences between points and lines of a biaffine plane and we also provide a pure algebraic model for it with the aid of finite heisenberg groups .
the obtained results are discussed in a more wide framework .
* keywords . *
coherent configuration , association scheme , biaffine plane , computer algebra , heisenberg group , non - schurian scheme , plausible reasonings .
* msc . * 05e30 , 51e15 . ' '' '' ' '' '' .
And you have already written the first three sentences of the full article: this paper reports about research conducted on the edge between algebraic graph theory ( briefly agt ) and computer algebra .
association schemes are one of the traditional areas of investigation in agt . for a good decade ,
catalogues of small association schemes have been available from the web site @xcite ..
Please generate the next two sentences of the article | it is known that all association schemes of order up to 14 are schurian , that is , they are coming from a suitable transitive permutation group in the standard manner .
first examples of non - schurian association schemes exist on 15 , 16 and 18 vertices . |
8,937 | Suppose that you have an abstract for a scientific paper: we study the two - terminal transport properties of a metallic single - walled carbon nanotube with good contacts to electrodes , which have recently been shown [ w. liang et al , nature 441 , 665 - 669 ( 2001 ) ] to conduct ballistically with weak backscattering occurring mainly at the two contacts .
the measured conductance , as a function of bias and gate voltages , shows an oscillating pattern of quantum interference .
we show how such patterns can be understood and calculated , taking into account luttinger liquid effects resulting from strong coulomb interactions in the nanotube .
we treat back - scattering in the contacts perturbatively and use the keldysh formalism to treat non - equilibrium effects due to the non - zero bias voltage . going beyond current experiments , we include the effects of possible ferromagnetic polarization of the leads to describe spin transport in carbon nanotubes .
we thereby describe both incoherent spin injection and coherent resonant spin transport between the two leads .
spin currents can be produced in both ways , but only the latter allow this spin current to be controlled using an external gate . in all cases , the spin currents , charge currents , and magnetization of the nanotube exhibit components varying quasiperiodically with bias voltage , approximately as a superposition of periodic interference oscillations of spin- and charge - carrying `` quasiparticles '' in the nanotube , each with its own period .
the amplitude of the higher - period signal is largest in single - mode quantum wires , and is somewhat suppressed in metallic nanotubes due to their sub - band degeneracy . .
And you have already written the first three sentences of the full article: spin transport represents a new branch in mesoscopic physics with several technological applications@xcite , e.g. information storage , magnetic sensors and potentially quantum computation@xcite .
while most theoretical models are based on fermi liquid theory , some work has been done on strongly correlated 1d systems using luttinger liquid theory@xcite .
this work has focused in the weak tunneling regime between the ferromagnet and the 1d system and found that spin transport may provide experimental evidence of spin charge separation , one of the main predictions of luttinger liquid theory that remains to be observed experimentally in an unambiguously accepted way . despite the possible technological applications and contributions to the study of spin charge separation in strongly correlated systems ,.
Please generate the next two sentences of the article | very little experimental work has been carried out on spin transport in 1d systems.@xcite this work is complicated by the use of multi - walled carbon nanotubes , and explored only situations with ferromagnetic contacts with parallel or antiparallel magnetizations .
early experimental work with nanotube devices was limited by poor contacts between the electrodes and the nanotube , and accordingly theoretical models focused in the weak tunneling regime . |
8,938 | Suppose that you have an abstract for a scientific paper: in order to model real ecological systems one has to consider many species that interact in complex ways .
however , most of the recent theoretical studies have been restricted to few species systems with rather trivial interactions .
the few studies dealing with larger number of species and/or more complex interaction schemes are mostly restricted to numerical explorations . in this paper
we determine , starting from the deterministic mean - field rate equations , for large classes of systems the space of coexistence fixed points at which biodiversity is maximal . for systems with a single coexistence fixed point
we derive complex ginzburg - landau equations that allow to describe space - time pattern realized in two space dimensions . for selected cases
we compare the theoretical predictions with the pattern observed in numerical simulations . .
And you have already written the first three sentences of the full article: understanding the generic conditions for biodiversity and species extinction remains a challenging problem in evolutionary and population dynamics @xcite .
whereas real world ecological systems are composed of tens or hundreds of species , theoretically well understood cases remain restricted to systems with only very few species that interact in rather simple ways .
but even these very simple cases have revealed a very rich behavior , due to the nonlinearity inherent to this type of systems ..
Please generate the next two sentences of the article | further progress in this field can be expected through the use of well established methods from nonlinear dynamics and statistical physics @xcite .
the simplest few species models , like the three - species rock - paper - scissors model or its four species variant , have been the subject of a range of in - depth studies that have unveiled many generic properties of systems with cyclic competition @xcite . |
8,939 | Suppose that you have an abstract for a scientific paper: we derive a mode - coupling theory for the slow dynamics of fluids confined in disordered porous media represented by spherical particles randomly placed in space .
its equations display the usual nonlinear structure met in this theoretical framework , except for a linear contribution to the memory kernel which adds to the usual quadratic term .
the coupling coefficients involve structural quantities which are specific of fluids evolving in random environments and have expressions which are consistent with those found in related problems .
numerical solutions for two simple models with pure hard core interactions lead to the prediction of a variety of glass transition scenarios , which are either continuous or discontinuous and include the possibility of higher - order singularities and glass - glass transitions .
the main features of the dynamics in the two most generic cases are reviewed and illustrated with detailed computations .
moreover , a reentry phenomenon is predicted in the low fluid - high matrix density regime and is interpreted as the signature of a decorrelation mechanism by fluid - fluid collisions competing with the localization effect of the solid matrix . .
And you have already written the first three sentences of the full article: over the last fifteen years , the dynamics of glassforming liquids under nanoscale confinement has attracted much attention .
a great variety of molecular systems under many different types of confinement has been subjected to virtually all available experimental techniques , while at the same time extensive studies of simple model systems using molecular dynamics simulations were undertaken @xcite .
the main reason for this rapidly growing interest is that confinement is considered as a potential tool to investigate the concept of cooperativity , a key ingredient of many glass transition theories @xcite . indeed , there are now many evidences that the dynamics of deeply supercooled liquids is inhomogeneous and that dynamically correlated groups of molecules play a crucial role in the slowing - down of the dynamics when the temperature is decreased ..
Please generate the next two sentences of the article | but , up to now , many questions pertaining , for instance , to the shape , size or temperature evolution of these dynamical heterogeneities remain essentially unanswered ( for recent progress , see , however , ref .
@xcite ) . in confinement , |
8,940 | Suppose that you have an abstract for a scientific paper: a multistable system generated by a piecewise linear ( pwl ) system based on the jerky equation is presented .
the systems behaviour is characterised by means of the nearest integer or @xmath0 function to control the switching events and to locate the corresponding equilibria among each of the commutation surfaces .
these surfaces are generated by means of the switching function dividing the space in regions equally distributed along one axis .
the trajectory of this type of system is governed by the eigenspectra of the coefficient matrix which can be adjusted by means of a bifurcation parameter .
the behaviour of the system can change from multi - scroll attractors into a mono - stable state to the coexistence of several single - scroll attractors into a multi - stable state .
numerical results of the dynamics and bifurcation analyses of their parameters are displayed to depict the multi - stable states .
multistability ; piecewise linear systems ; eigenspectra ; chaos ; multi - scroll attractor ; round function ; bifurcation . .
And you have already written the first three sentences of the full article: throughout history , the scientific community has had the task of studying the properties of different dynamical systems and their importance to the environment where they are developed .
for example , the fact that some dynamical systems are chaotic and have a critical dependence on initial conditions is known since late last century .
this important characteristic has been correlated with the coexistence of several possible final stable states for a given set of parameters @xcite . in dissipative systems , this property is called generalized multistability " so it can be distinguished from the ordinary coexistence of stationary solutions @xcite ..
Please generate the next two sentences of the article | the term multistability was first used with respect to visual perception in 1971 @xcite ; nevertheless , the occurrence of multistability is very common in various fields of science , such as chemistry @xcite , optics @xcite , physics @xcite and biological systems @xcite .
nevertheless , the importance of generating multistable structures resides in the wide variety of applications that exist : synchronization , complex networks , communication , climate , etc . in this work |
8,941 | Suppose that you have an abstract for a scientific paper: we show that a geodesic metric space is hyperbolic in the sense of gromov if and only if intersections of balls have bounded eccentricity .
in particular , @xmath0-trees are characterized among geodesic metric spaces by the property that the intersection of any two balls is always a ball .
both gromov hyperbolicity and cat(@xmath1 ) geometry can be characterised in terms of the geometry of the intersection of balls . .
And you have already written the first three sentences of the full article: it is well known that in an @xmath2-tree the intersection of any two metric balls is itself a metric ball . in this paper
we will show that this is actually a characterization of @xmath0-trees , and that , more generally , the geometry of the intersection of balls encodes information about the curvature of a geodesic metric space .
recall from @xcite , @xcite , @xcite or @xcite that a geodesic metric space is _ hyperbolic _ ( in the sense of gromov ) if there is a constant @xmath3 such that for any geodesic triangle , any one side is contained in the @xmath4-neighborhood of the union of the two other sides ..
Please generate the next two sentences of the article | we prove the following characterization of hyperbolicity .
[ qb]a geodesic metric space @xmath5 is hyperbolic if and only if the intersection of any two metric balls is at uniformly bounded hausdorff distance from a ball . studying curvature in terms of the geometry of the intersection of metric balls turns out to be very natural and both gromov hyperbolicity and the notion of cat(@xmath1 ) geometry may be characterised in theses terms ( see section [ ext ] ) . |
8,942 | Suppose that you have an abstract for a scientific paper: recently li and xia have proposed a transmission scheme for wireless relay networks based on the alamouti space time code and orthogonal frequency division multiplexing to combat the effect of timing errors at the relay nodes .
this transmission scheme is amazingly simple and achieves a diversity order of two for any number of relays .
motivated by its simplicity , this scheme is extended to a more general transmission scheme that can achieve full cooperative diversity for any number of relays .
the conditions on the distributed space time code ( dstc ) structure that admit its application in the proposed transmission scheme are identified and it is pointed out that the recently proposed full diversity four group decodable dstcs from precoded co - ordinate interleaved orthogonal designs and extended clifford algebras satisfy these conditions .
it is then shown how differential encoding at the source can be combined with the proposed transmission scheme to arrive at a new transmission scheme that can achieve full cooperative diversity in asynchronous wireless relay networks with no channel information and also no timing error knowledge at the destination node .
finally , four group decodable distributed differential space time codes applicable in this new transmission scheme for power of two number of relays are also provided . .
And you have already written the first three sentences of the full article: coding for cooperative wireless relay networks has attracted considerable attention recently . distributed space time coding was proposed as a coding strategy to achieve full cooperative diversity in @xcite assuming that the signals from all the relay nodes arrive at the destination at the same time . but this assumption is not close to practicality since the relay nodes are geographically distributed . in @xcite , a transmission scheme based on orthogonal frequency division multiplexing ( ofdm ) at the relay nodes
was proposed to combat the timing errors at the relays and a high rate space time code ( stc ) construction was also provided . however , the maximum likelihood ( ml ) decoding complexity for this scheme is prohibitively high especially for the case of large number of relays .
several other works in the literature propose methods to combat the timing offsets but most of them are based on decode and forward at the relay node and moreover fail to address the decoding complexity issue . in @xcite , a simple transmission scheme to combat timing errors at the relay nodes was proposed ..
Please generate the next two sentences of the article | this scheme is particularly interesting because of its associated low ml decoding complexity . in this scheme
, ofdm is implemented at the source node and time reversal / conjugation is performed at the relay nodes on the received ofdm symbols from the source node . |
8,943 | Suppose that you have an abstract for a scientific paper: we present modelling of line polarization to study multi - dimensional geometry of stripped - envelope core - collapse supernovae ( sne ) .
we demonstrate that a purely axisymmetric , two - dimensional geometry can not reproduce a loop in the stokes @xmath0 diagram , i.e. , a variation of the polarization angles along the velocities associated with the absorption lines . on the contrary
, three - dimensional ( 3d ) clumpy structures naturally reproduce the loop .
the fact that the loop is commonly observed in stripped - envelope sne suggests that sn ejecta generally have a 3d structure .
we study the degree of line polarization as a function of the absorption depth for various 3d clumpy models with different clump sizes and covering factors .
comparison between the calculated and observed degree of line polarization indicates that a typical size of the clump is relatively large , @xmath1 of the photospheric radius .
such large - scale clumps are similar to those observed in the sn remnant cassiopeia a. given the small size of the observed sample , the covering factor of the clumps is only weakly constrained ( @xmath2 ) .
the presence of large - scale clumpy structure suggests that the large - scale convection or standing accretion shock instability takes place at the onset of the explosion . .
And you have already written the first three sentences of the full article: [ cols="^,^,^ " , ]
next we study polarization properties of 3d models . motivated by 3d simulations of neutrino - driven explosions , where various sizes of complex structure appear , we set up 3d models by randomly placing different numbers of spherical clumps with different sizes .
here we introduce two parameters to depict the model : the size parameter of the clumps @xmath3 , i.e. , the radius of the clump normalized by the photospheric radius ( @xmath4 ) and the photospheric covering factor ( @xmath5 ) . since the optical depth near.
Please generate the next two sentences of the article | the photosphere is the most important for line formation , the covering factor is evaluated by taking into account the clumps only in a shell between @xmath6 and @xmath7 km s@xmath8 .
note that , as in the 2d cases , the line optical depth in our models has a spherical component and it is enhanced by a factor of @xmath9 within the clumps . |
8,944 | Suppose that you have an abstract for a scientific paper: this paper concerns the class of contractible open 3-manifolds which are `` locally finite strong end sums '' of eventually end - irreducible whitehead manifolds .
it is shown that whenever a 3-manifold in this class is a covering space of another 3-manifold the group of covering translations must be a free group .
it follows that such a 3-manifold can not cover a closed 3-manifold . for each countable free group a specific uncountable family of irreducible open 3-manifolds
is constructed whose fundamental groups are isomorphic to the given group and whose universal covering spaces are in this class and are pairwise non - homeomorphic . .
And you have already written the first three sentences of the full article: suppose @xmath0 is a closed , connected , orientable , irreducible 3-manifold such that @xmath1 is infinite .
the `` universal covering conjecture '' states that the universal covering space @xmath2 of @xmath0 must be homeomorphic to @xmath3 .
it is known that @xmath2 is an irreducible , contractible , open 3-manifold @xcite . a * whitehead manifold * is an irreducible , contractible , open 3-manifold which is not homeomorphic to @xmath3 ..
Please generate the next two sentences of the article | the universal covering conjecture is equivalent to the statement that whitehead manifolds can not cover closed 3-manifolds .
in @xcite the author proved that `` genus one '' whitehead manifolds can not non - trivially cover other 3-manifolds , even non - compact ones . |
8,945 | Suppose that you have an abstract for a scientific paper: let @xmath0 .
in this paper we study the right permutation action of the symmetric group @xmath1 on the set of all the brauer @xmath2-diagrams .
a new basis for the free @xmath3-module @xmath4 spanned by these brauer @xmath2-diagrams is constructed , which yields specht filtrations for @xmath4 . for any @xmath5-dimensional vector space @xmath6 over a field of arbitrary characteristic
, we give an explicit and characteristic free description of the annihilator of the @xmath2-tensor space @xmath7 in the brauer algebra @xmath8 .
in particular , we show that it is a @xmath1-submodule of @xmath8 . .
And you have already written the first three sentences of the full article: let @xmath9 be an indeterminate over @xmath3 .
the brauer algebra @xmath10 over @xmath11 $ ] is a unital associative @xmath11$]-algebra with generators @xmath12 @xmath13 and relations ( see @xcite ) : @xmath14 @xmath10 is a free @xmath11$]-module with rank @xmath15 . for any @xmath11$]-algebra @xmath16 with @xmath9 specialized to @xmath17
, we define @xmath18}{\mathfrak{b}}_n(x)$ ] ..
Please generate the next two sentences of the article | this algebra was first introduced by richard brauer ( see @xcite ) when he studied how the @xmath2-tensor space @xmath19 decomposes into irreducible modules over the orthogonal group @xmath20 or the symplectic group @xmath21 , where @xmath6 is an orthogonal vector space or a symplectic vector space . in brauer s original formulation ,
the algebra @xmath10 was defined as the complex linear space with basis the set @xmath22 of all the brauer @xmath2-diagrams , graphs on @xmath23 vertices and @xmath2 edges with the property that every vertex is incident to precisely one edge . |
8,946 | Suppose that you have an abstract for a scientific paper: we present four new exoplanets : hip 14810 b & c , hd 154345 b , and hd 187123 c. the two planets orbiting hip 14810 , from the n2k project , have masses of 3.9 and 0.76 @xmath0 .
we have searched the radial velocity time series of 90 known exoplanet systems and found new residual trends due to additional , long period companions .
two stars known to host one exoplanet have sufficient curvature in the residuals to a one planet fit to constrain the minimum mass of the outer companion to be substellar : hd 68988 c with @xmath1 and hd 187123 c with @xmath2 , both with @xmath3 y. we have also searched the velocity residuals of known exoplanet systems for prospective low - amplitude exoplanets and present some candidates .
we discuss techniques for constraining the mass and period of exoplanets in such cases , and for quantifying the significance of weak rv signals .
we also present two substellar companions with incomplete orbits and periods longer than 8 y : hd 24040 b and hd 154345 b with @xmath4 and @xmath5 @xmath0 , respectively . .
And you have already written the first three sentences of the full article: of the 151 nearby stars known to harbor one or more planets , 19 are well - characterized multiple - planet systems , and an additional 24 show radial velocity ( rv ) residuals indicative of additional companions @xcite .
for instance , @xcite reported additional companions around five stars , including two revealed by incomplete orbits apparent in the rv residuals ( hd 50499 and hd 217107 ) , and one as a short - period , low amplitude variation in the residuals of the fit to a long - period outer companion .
@xcite detected a 7.5 earth - mass mass companion to gj 876 in a 2-day period through analysis of the rv residuals to a 2-planet dynamical fit of the more massive , outer exoplanets ..
Please generate the next two sentences of the article | @xcite similarly analyzed the rv residuals of 4 stars to search for neptune - mass companions .
very little is known about the frequency or nature of exoplanets with orbital distances greater than 5 au @xcite . |
8,947 | Suppose that you have an abstract for a scientific paper: a comparison is made between conventional michaelis - menten kinetics and two models that take into account the duration of the conformational changes that take place at the molecular level during the catalytic cycle of a monomer .
the models consider the time that elapses from the moment an enzyme - substrate complex forms until the moment a product molecule is released , as well as the recovery time needed to reset the conformational change that took place . in the first model
the dynamics is described by a set of delayed differential equations , instead of the ordinary differential equations associated to michaelis - menten kinetics . in the second model the delay , the discretization inherent to enzyme reactions and the stochastic binding of substrates to enzimes at the molecular level is considered .
all three models agree at equilibrium , as expected ; however , out - of - equilibrium dynamics can differ substantially .
in particular , both delayed models show oscillations at low values of the michaelis constant which are not reproduced by the michaelis - menten model .
additionally , in certain cases , the dynamics shown by the continuous delayed model differs from the dynamics of the discrete delayed model when some reactant become scarce
. , nonlinear dynamics , enzyme dynamics , enzyme reaction simulation , enzyme kinetics .
And you have already written the first three sentences of the full article: for over a century , the conventional way to represent many enzyme reactions has been based on the michaelis - menten kinetics @xcite ( hereafter mm model ) , in which substrate s binds reversibly with enzyme e to form an enzyme - substrate complex es , which is later transformed into product p and free enzyme e. derivation of the michaelis - menten equation is based on the following scheme @xcite : however , there is strong evidence suggesting that enzime activity depends on conformational changes in the enzyme structure @xcite .
it is therefore reasonable to assume that a conformational change takes place from the moment an es complex forms to the moment a product p is released ; such change requires a certain time for its completion .
this conformational change must then be reset before the enzyme is ready to bind substrate again , and so a recovery time must elapse once p is released ..
Please generate the next two sentences of the article | single - enzyme studies @xcite and nuclear magnetic resonance spectroscopy studies @xcite support these notions .
a scheme that considers enzyme regeneration is presented by @xcite , , + where @xmath0 represents recovering enzyme . |
8,948 | Suppose that you have an abstract for a scientific paper: we discuss the ground state properties of the system composed of a normal metal sandwiched between ferromagnet and superconductor within a tight binding hubbard model . we have solved the spin - polarized hartree - fock - gorkov equations together with the maxwell s equation ( ampere s law ) and found a proximity induced fulde - ferrell - larkin - ovchinnikov ( fflo ) state in this system . here
we show that the inclusion of the normal metal layer in between those subsystems does not necessarily lead to the suppression of the fflo phase .
moreover , we have found that depending on the thickness of the normal metal slab the system can be switched periodically between the state with the spontaneous current flowing to that one with no current .
all these effects can be explained in terms of the andreev bound states formed in such structures . .
And you have already written the first three sentences of the full article: the proximity effect between a ferromagnet and a superconductor has attracted much attention recently due to its potential applications in such areas of technology as magnetoelectronics @xcite or quantum computing @xcite . the proximity effect in ferromagnet - superconductor (
f - s ) structures is also important from the point of view of the scientific interest as it allows the study of the interplay between ferromagnetism and superconductivity @xcite .
due to time reversal symmetry breaking the proximity effect in f - s structures leads to new phenomena , not observed in usual normal metal - superconductor ( n - s ) proximity systems ..
Please generate the next two sentences of the article | those are : oscillations of the superconducting transition temperature @xcite , density of states @xcite and superconducting pairing amplitude in f - s multilayers , josephson @xmath0-junction behavior in s - f - s heterostructures @xcite , a giant mutual proximity effect in s - f systems @xcite , spin valve @xcite or spontaneous currents in f - s bilayers @xcite . for review of the literature on those and related effects see @xcite .
we have recently examined f - s proximity system and found that a spontaneously generated current flows on both sides of the interface @xcite . |
8,949 | Suppose that you have an abstract for a scientific paper: we consider analysis targets at the international linear collider in which only a single photon can be observed . for such processes , we have developed a method which uses likelihood distributions using the full event information ( photon energy and angle ) .
the method was applied to a search for neutralino pair production with a photon from initial state radiation ( isr ) in the case of supergravity in which the neutralino is the lightest supersymmetric particle .
we determine the cross section required to observe the neutralino pair production with isr as a function of the neutralino mass in the range of 100 to 250 gev . .
And you have already written the first three sentences of the full article: weakly interacting massive particles ( wimps ) are important study targets in current and future collider experiments since the wimps provide a solution to the dark matter problem . in this study , we investigate the prospects of discovering the direct pair production of wimps at the international linear collider ( ilc ) using the energy and angle spectra of the photons from initial state radiation ( isr ) @xcite .
we make the assumption that , among the particles beyond the standard model , the wimps are the only kinematically accessible at the center - of - mass ( cm ) energy of 500 gev proposed for the ilc .
similar past searches using single photons have been performed by e.g. @xcite ..
Please generate the next two sentences of the article | prospects of such measurements have been discussed in many literature @xcite and , in particular , at the ilc @xcite which uses a cut - and - count approach .
our method uses the two - dimensional energy and angle distributions of the isr photon and thus exploits the full information of the event . |
8,950 | Suppose that you have an abstract for a scientific paper: the rich variety of densest columnar structures of identical hard spheres inside a cylinder can surprisingly be constructed from a simple and computationally fast sequential deposition of cylinder - touching spheres , if the cylinder - to - sphere diameter ratio is @xmath0 $ ] .
this provides a direction for theoretically deriving _ all _ these densest structures and for constructing such densest packings with nano- , micro- , colloidal or charged particles , which all self - assemble like hard spheres . .
And you have already written the first three sentences of the full article: the problem of finding the densest configurations of identical hard spheres inside a cylinder is related to many different aspects in science and engineering : similar densest structures ( e.g. zigzags and helices ) have in recent years been observed for the self - assembly of nano - spheres inside carbon nanotubes @xcite , charged particles on cylindrical surfaces @xcite , micro - spheres inside micro - channels @xcite and colloidal particles inside cylindrical channels @xcite , and also for the formation of colloidal crystal wires @xcite , the reason being that in all such cases the particles close - pack themselves like hard spheres .
relevant problems of interest include ( i ) finding a theoretical derivation of the corresponding densest packings of hard spheres and ( ii ) finding a general methodology for constructing them in practice .
for this problem , a wide range of chiral and achiral densest structures for a diameter ratio of @xmath1 cylinder diameter / sphere diameter @xmath2 $ ] have previously been found by simulated annealing @xcite and by other computational means @xcite , where @xmath3 is a critical value of @xmath4 below which the densest configurations are entirely made up of cylinder - touching spheres . in particular ,.
Please generate the next two sentences of the article | the densest structures for @xmath5 $ ] , which have their entire structural information contained on the cylinder surface , can be described by a phyllotactic scheme @xcite that is relevant to the study of plant morphology .
$ ] : ( a ) the achiral planar zigzag at @xmath6 , ( b ) the chiral single helix at @xmath7 , ( c ) the chiral double helix at @xmath8 , and ( d ) the achiral doublets , which have two spheres located on one @xmath9 position , at @xmath10 . for each case , the required periodicity @xmath11 along @xmath12 is indicated by a solid arrow . , width=272,height=204 ] in this article , it is shown that @xmath13 the densest structures for @xmath0 $ ] can surprisingly be constructed from a simple and computationally fast sequential deposition of cylinder - touching spheres which maximizes the number of spheres per unit length everywhere along the cylinder axis ( typically less than 15 minutes of computational time for each value of @xmath4 ; much faster than simulated annealing which sometimes can take up a whole week @xcite ) . as demonstrated in fig . |
8,951 | Suppose that you have an abstract for a scientific paper: we demonstrate three - photon excitation in quantum dots with a mode - locked fiber laser operating in the telecommunications band .
we compare spectra and intensity dependence of fluorescence from one- and three - photon excitation of commercially available 640 nm quantum dots , using a 372 nm diode laser for one - photon excitation and 116 fs pulses from a mode - locked fiber laser with a center wavelength of 1575 nm for three - photon excitation . .
And you have already written the first three sentences of the full article: quantum dots are semiconductor nanocrystals , 1 - 20 nm in size @xcite , that possess a discrete energy level structure .
the level structure is determined by the size , composition and shape of the quantum dot @xcite .
particular focus has been placed on ii - vi semiconductors , such as cdse @xcite . by selecting for size.
Please generate the next two sentences of the article | , the fluorescence emission can be tailored to the application , which is attractive for use in biological labels @xcite .
in addition , the quantum dot surface can be chemically functionalized to bind to specific biomolecules . compared to other fluorescent molecules , |
8,952 | Suppose that you have an abstract for a scientific paper: almost a hundred years ago , two different expressions were proposed for the energy momentum tensor of an electromagnetic wave in a dielectric .
minkowski s tensor predicted an increase in the linear momentum of the wave on entering a dielectric medium , whereas abraham s tensor predicted its decrease .
theoretical arguments were advanced in favour of both sides , and experiments proved incapable of distinguishing between the two . yet more forms were proposed , each with their advocates who considered the form that they were proposing to be the one true tensor .
this paper reviews the debate and its eventual conclusion : that no electromagnetic wave energy
momentum tensor is complete on its own .
when the appropriate accompanying energy momentum tensor for the material medium is also considered , experimental predictions of all the various proposed tensors will always be the same , and the preferred form is therefore effectively a matter of personal choice . .
And you have already written the first three sentences of the full article: the correct form of the energy momentum tensor of an electromagnetic wave , and hence the momentum of an electromagnetic wave in a dielectric medium , has been debated for almost a century .
two different forms of the energy
momentum tensor were originally proposed by @xcite and @xcite , though more have been added in later years @xcite ..
Please generate the next two sentences of the article | the question regularly attracts experimental interest , as on initial inspection it may appear that some of the different tensors give rise to distinct and potentially useful physical consequences .
we discuss why this is not the case , reviewing the key experiments of @xcite , @xcite , and @xcite , and theoretical work including that of @xcite , @xcite , @xcite , @xcite , @xcite , and @xcite , the latter four authors demonstrating explicitly and directly the equivalence of a number of different energy momentum tensors . |
8,953 | Suppose that you have an abstract for a scientific paper: we have obtained the decay asymmetry parameters in non - mesonic weak decay of polarized @xmath0-hypernuclei by measuring the proton asymmetry .
the polarized @xmath0-hypernuclei , , , and , were produced in high statistics via the ( @xmath1,k@xmath2 ) reaction at 1.05 gev/@xmath3 in the forward angles .
preliminary analysis shows that the decay asymmetry parameters are very small for these s - shell and p - shell hypernuclei . .
And you have already written the first three sentences of the full article: the non - mesonic weak decay ( nmwd : @xmath0n@xmath4nn ) of @xmath0-hypernuclei gives us a very unique opportunity to study baryon - baryon weak interaction .
there exist several experimental observables ; life times(total decay rates ) , branching ratios(@xmath5(@xmath0p@xmath4np ) , @xmath5(@xmath0n@xmath4nn ) ) , etc .
the asymmetry parameter of decay proton from the @xmath0p@xmath4np process , , is another important observable to investigate the reaction mechanism of nmwd , because it comes from the interference between the parity - conserving and parity - violating amplitudes ..
Please generate the next two sentences of the article | the decay angular distribution of protons from the nmwd of polarized hypernuclei , @xmath6(@xmath7 ) , is expressed as @xmath8 , where @xmath9 is the asymmetry , @xmath10 denotes the polarization of a @xmath0-hypernucleus , and @xmath7 means the emission angle of protons with respect to the polarization axis .
so far , two experiments reported the asymmetry parameters of the nmwd s of @xcite and @xcite . in kek - ps e160 , |
8,954 | Suppose that you have an abstract for a scientific paper: we investigate the evolutionary status of four stars : v348 sgr , dy cen and mv sgr in the galaxy and hv 2671 in the lmc .
these stars have in common random deep declines in visual brightness which are characteristic for r coronae borealis ( rcb ) stars .
rcb stars are typically cool , hydrogen deficient supergiants .
the four stars studied in this paper are hotter ( t@xmath0 = 15 - 20 kk ) than the majority of rcb stars ( t@xmath0 = 5000 - 7000 k ) . although these are commonly grouped together as the _ hot rcb stars
_ they do not necessarily share a common evolutionary history .
we present new observational data and an extensive collection of archival and previously - published data which is reassessed to ensure internal consistency .
we find temporal variations of various properties on different time scales which will eventually help us to uncover the evolutionary history of these objects .
dy cen and mv sgr have typical rcb helium abundances which excludes any currently known post - agb evolutionary models .
moreover , their carbon and nitrogen abundances present us with further problems for their interpretation .
v348 sgr and hv 2671 are in general agreement with a born - again post - agb evolution and their abundances are similar to wolf - rayet central stars of pn .
the three galactic stars in the sample have circumstellar nebulae which produce forbidden line radiation ( for hv 2671 we have no information ) . v348
sgr and dy cen have low density , low expansion velocity nebulae ( resolved in the case of v348 sgr ) , while mv sgr has a higher density , higher expansion velocity nebula .
all three stars on the other hand have split emission lines which indicate the presence of an equatorial bulge but _ not _ of a keplerian disk . in addition , the historical light - curves for the three galactic hot rcb stars , show evidence for a significant fading in their maximum - light brightnesses of @xmath11 mag over the last 70 yr . from this we deduce that their effective....
And you have already written the first three sentences of the full article: the r coronae borealis ( rcb ) stars are hydrogen - deficient supergiants , characterized by spectacular drops in visual brightness which occur at random intervals .
rcb stars are a very rare phenomenon with only about 35 known in the galaxy .
the atmospheres of these stars are composed mostly of helium with carbon and nitrogen enrichment ..
Please generate the next two sentences of the article | their hydrogen depletion varies between undetectable hydrogen to severely depleted ( 5% by mass ) .
the declines in brightness are caused by the formation of clouds of carbon dust in front of the star ( see clayton 1996 for a review ) . to explain the existence of rcb stars , two scenarios have been proposed . in the first scenario |
8,955 | Suppose that you have an abstract for a scientific paper: cosmic strings are predicted in many models beyond the standard model of particle physics . in models which admit strings , a network of strings
will inevitably be formed in a phase transition in the early universe and will persist to the present time .
strings leave behind distinctive features in cosmology . searching for these signatures in new observational windows
provides a way to constrain particle physics at the high energy scale and is thus complementary to searches for new physics at the low energy end , for example at the lhc .
specifically , i will discuss signatures of cosmic strings in cosmic microwave background polarization maps and in 21 cm redshift surveys . .
And you have already written the first three sentences of the full article: cosmic strings @xcite are linear topological defects which arise in a range of relativistic quantum field theories ( for reviews see e.g @xcite ) .
good analogs of cosmic strings are vortex lines in superfluids and superconductors .
line defects in crystals can be viewed as another analog system ..
Please generate the next two sentences of the article | cosmic strings form lines of trapped energy density , and this energy density can curve space - time and have important effects in cosmology @xcite .
cosmic strings are predicted to form in many particle physics models beyond the standard model . in particular , they are predicted to form at the end of inflation in many inflationary models , e.g. supergravity models @xcite and brane inflation models @xcite . |
8,956 | Suppose that you have an abstract for a scientific paper: stepwise refinement of algebraic specifications is a well known formal methodology for program development . however , traditional notions of refinement based on signature morphisms are often too rigid to capture a number of relevant transformations in the context of software design , reuse , and adaptation .
this paper proposes a new approach to refinement in which signature morphisms are replaced by _
logical interpretations _ as a means to witness refinements .
the approach is first presented in the context of equational logic , and later generalised to deductive systems of arbitrary dimension .
this allows , for example , refining sentential into equational specifications and the latter into modal ones . .
And you have already written the first three sentences of the full article: the industrial demand for high - assurance software opens a window of opportunity for mathematically based development methods , able to design complex systems at ever - increasing levels of reliability and security .
this paper s contribution is placed at a specific corner of the broad landscape of formal methods for software development : that of _ algebraic specification _
@xcite , a family of methods which , having played a pioneering role , constitutes at present a large and mature body of knowledge and active research ..
Please generate the next two sentences of the article | such methods have a double origin .
on the one hand they can be traced back to early work on data abstraction and modular decomposition of programs @xcite . on the other hand , to research on semantics of program specifications building on results from algebraic logic and model theory . especially relevant in this respect is the original work of the so - called adj group @xcite whose initial algebra semantics was the first , full formal approach to software development put forward . this double origin , |
8,957 | Suppose that you have an abstract for a scientific paper: we review our recent progress in the determination of the high - density correlation energy @xmath0 in two - electron systems .
several two - electron systems are considered , such as the well known helium - like ions ( helium ) , and the hooke s law atom ( hookium ) .
we also present results regarding two electrons on the surface of a sphere ( spherium ) , and two electrons trapped in a spherical box ( ballium ) .
we also show that , in the large - dimension limit , the high - density correlation energy of two opposite - spin electrons interacting _ via _ a coulomb potential is given by @xmath1 for any radial external potential @xmath2 , where @xmath3 is the dimensionality of the space .
this result explains the similarity of @xmath0 in the previous two - electron systems for @xmath4 . .
And you have already written the first three sentences of the full article: the hartree - fock ( hf ) approximation ignores the correlation between electrons , but gives roughly 99% of the total electronic energy @xcite .
moreover , it is often accurate for the prediction of molecular structure @xcite , computationally cheap and can be applied to large systems , especially within local ( linear - scaling ) strategies @xcite . to reduce the computational cost still further ,
various numerical techniques have been developed including , for example , density fitting ( or resolution of the identity ) @xcite , pseudospectral and cholesky decomposition @xcite , dual basis methods @xcite , and both attenuation @xcite and resolution @xcite of the coulomb operator ..
Please generate the next two sentences of the article | unfortunately , the part of the energy which the hf approximation ignores can have important chemical effects and this is particularly true when bonds are formed and/or broken . consequently
, realistic model chemistries require a satisfactory treatment of electronic correlation . |
8,958 | Suppose that you have an abstract for a scientific paper: we report on the first ground - based measurement of the relativistic beaming effect ( aka doppler boosting ) .
we observed the beaming effect in the detached , non - interacting eclipsing double white dwarf ( wd ) binary nltt 11748 .
our observations were motivated by the system s high mass ratio and low luminosity ratio , leading to a large beaming - induced variability amplitude at the orbital period of 5.6 hr .
we observed the system during 3 nights at the 2.0 m faulkes telescope north with the sdss-@xmath0 filter , and fitted the data simultaneously for the beaming , ellipsoidal and reflection effects .
our fitted relative beaming amplitude is @xmath1 , consistent with the expected amplitude from a blackbody spectrum given the photometric primary radial velocity amplitude and effective temperature .
this result is a first step in testing the relation between the photometric beaming amplitude and the spectroscopic radial velocity amplitude in nltt 11748 and similar systems .
we did not identify any variability due to the ellipsoidal or reflection effects , consistent with their expected undetectable amplitude for this system .
low - mass , helium - core wds are expected to reside in binary systems where in some of those systems the binary companion is a faint c / o wd and the two stars are detached and non - interacting , as in the case of nltt 11748 .
the beaming effect can be used to search for the faint binary companion in those systems using wide - band photometry . .
And you have already written the first three sentences of the full article: the movement of a light - emitting object relative to an observer causes relativistic beaming of the light ( aka doppler boosting ) since the specific intensity is not a relativistic invariant . when the object s radial velocity ( rv ) is periodically modulated , as is the case in binary systems , a periodic sinusoidal variation in the observed flux is induced .
this effect is one of three that can be seen in light curves of binary systems , not necessarily eclipsing .
the other two are the ellipsoidal effect , when a member of the binary system is tidally affected by the gravitational pull of its companion , and the reflection effect , when light originating from one component is reflected by the other ..
Please generate the next two sentences of the article | the three effects were discussed in the context of planet - host stars by @xcite , and main sequence stellar binaries by @xcite . both studies addressed binary systems with orbital periods much longer than a day , finding that the required photometric accuracy necessitates space - based observations .
observational detections of the beaming effect are rare . |
8,959 | Suppose that you have an abstract for a scientific paper: type iip ( plateau ) supernovae are the most commonly observed variety of core collapse events .
they have been detected in a wide range of wavelengths from radio , through optical to x - rays .
the standard picture of a type iip supernova has the blastwave interacting with the progenitor s circumstellar matter to produce a hot region bounded by a forward and a reverse shock .
this region is thought to be responsible for most of the x - ray and radio emission from these objects .
yet the origin of x - rays from these supernovae is not well understood quantitatively .
the relative contributions of particle acceleration and magnetic field amplification in generating the x - ray and radio emission need to be determined . in this work
we analyze archival chandra observations of sn 2004dj , the nearest supernova since sn 1987a , along with published radio and optical information .
we determine the pre - explosion mass loss rate , blastwave velocity , electron acceleration and magnetic field amplification efficiencies .
we find that a greater fraction of the thermal energy goes into accelerating electrons than into amplifying magnetic fields .
we conclude that the x - ray emission arises out of a combination of inverse compton scattering by non - thermal electrons accelerated in the forward shock and thermal emission from supernova ejecta heated by the reverse shock . .
And you have already written the first three sentences of the full article: core collapse supernovae with hydrogen lines near maximum light and a pronounced plateau in their visible band light curve that remain within @xmath0 mag of maximum brightness for an extended period are called type iip supernovae .
the plateau duration is often 60 - 100 rest - frame days and is followed by an exponential tail powered by radioactive decay at late times .
type iip supernovae constitute about 67% of all core collapse supernovae in a volume limited sample ( @xmath1 mpc ) @xcite ..
Please generate the next two sentences of the article | their characteristic optical light curves are attributed to the hydrogen envelope of the progenitor remaining largely intact before the core collapse .
several lines of evidence suggest that these stars were red supergiants when they exploded . |
8,960 | Suppose that you have an abstract for a scientific paper: we present the first detailed study of the large , @xmath0 pc diameter , inner - galaxy region w 39 .
radio recombination line observations combined with absorption spectra and galactic rotation models show that the region lies at @xmath1 km s@xmath2 corresponding to a near kinematic distance of 4.5@xmath3 kpc .
analysis of radio continuum emission shows that the region is being powered by a cluster of ob stars with a combined hydrogen - ionizing luminosity of @xmath4 , and that there are three compact regions located on the periphery of w 39 , each with @xmath5 ( single o7 - o9 v star equivalent ) . in the infrared
, w 39 has a hierarchical bubble morphology , and is a likely site of sequential star formation involving massive stars .
kinematic models of the expansion of w 39 yield timescales of order myr consistent with a scenario where the formation of the smaller regions has been triggered by the expansion of w 39 . using _ spitzer _
glimpse and mipsgal data we show that star - formation activity is not distributed uniformly around the periphery of w 39 but is concentrated in two areas that include the compact regions as well as a number of intermediate - mass class i and class ii ysos . .
And you have already written the first three sentences of the full article: w 39 is a large region in the inner galaxy ( @xmath6 , @xmath7 ) first identified in the @xcite 1.4 ghz radio continuum survey and more recently cataloged as a large infrared `` bubble '' by both professional astronomers ( n24 ; * ? ? ?
* ) and citizen scientists ( mwp1g18908 - 003146 ; * ? ? ?
it is a significant high - mass star - forming region and a possible example of sequential or triggered star formation based on the hierarchical bubble structure seen in the infrared , but , owing to its highly obscured location in the inner galaxy , it has been poorly studied ..
Please generate the next two sentences of the article | recent high - resolution ( sub - arcminute ) surveys at radio and infrared wavelengths have provided an opportunity to examine this region in detail for the first time .
this paper presents an analysis of the region itself along with an investigation of the influence of the region on star formation in its vicinity . in the next section |
8,961 | Suppose that you have an abstract for a scientific paper: one of the experimental tests of lorentz invariance violation is to measure the helicity dependence of the propagation velocity of photons originating in distant cosmological obejcts . using a recent determination of the distance of the gamma - ray burst grb 041219a , for which a high degree of polarization is observed in the prompt emission , we are able to improve by 4 orders of magnitude the existing constraint on lorentz invariance violation , arising from the phenomenon of vacuum birefringence . .
And you have already written the first three sentences of the full article: on general grounds one expects that the two fundamental theories of contemporary physics , the theory of general relativity and the quantum theory in the form of the standard model of particle physics , can be unified at the planck energy scale .
this unification requires to quantize gravity , which leads to very fundamental difficulties .
one is related with the energy of the fundamental vacumm state ..
Please generate the next two sentences of the article | another one is the status of lorentz invariance : the fuzzy nature of space time in quantum gravity may lead to violations of this fundamental symmetry . for the last two decades theoretical studies and experimental searches of lorentz invariance violation ( liv )
have received a lot of attention ( see e.g. the reviews by * ? ? ? |
8,962 | Suppose that you have an abstract for a scientific paper: this paper presents a connection between the topological properties of hardcore bosons and that of magnons in quantum spin magnets .
we utilize the haldane - like hardcore bosons on the honeycomb lattice as an example .
we show that this system maps to a spin-@xmath0 quantum xy model with a next - nearest - neighbour dzyaloshinsky - moriya interaction .
we obtain the magnon excitations of the quantum spin model and compute the edge states , berry curvature , thermal and spin nernst conductivities . due to the mapping from spin variables to bosons ,
the hardcore bosons possess the same nontrivial topological properties as those in quantum spin system .
these results are important in the study of magnetic excitations in quantum magnets and they are also useful for understanding the control of ultracold bosonic quantum gases in honeycomb optical lattices , which is experimentally accessible . .
And you have already written the first three sentences of the full article: in recent years , topologically nontrivial properties of band theory in electronic systems have become the driving force in condensed matter physics @xcite . although electronic band theory has been studied over the past decades , the topological properties associated with it have only been appreciated recently .
the haldane model @xcite was the first example of quantum anomalous hall effect ( zero magnetic field quantum hall effect ) in electronic systems that originates completely from the topology of the energy bands . for many decades ,
this model was deemed as a toy model due to lack of experimental evidence ..
Please generate the next two sentences of the article | quite recently , the experimental realization of haldane model @xcite has been reported in ultracold fermionic atoms in a periodically modulated optical honeycomb lattice @xcite .
this observation has motivated numerous theoretical studies of the effects of interactions in the so - called haldane - hubbard model @xcite . |
8,963 | Suppose that you have an abstract for a scientific paper: a supersymmetric formulation of a three - dimensional sym chern simons theory using light - cone quantization is presented , and the supercharges are calculated in light - cone gauge . the theory is dimensionally reduced by requiring all fields to be independent of the transverse dimension .
the result is a non - trivial two - dimensional supersymmetric theory with an adjoint scalar and an adjoint fermion .
we perform a numerical simulation of this sym chern simons theory in 1 + 1 dimensions using sdlcq ( supersymmetric discrete light - cone quantization ) .
we find that the character of the bound states of this theory is very different from previously considered two - dimensional supersymmetric gauge theories .
the low - energy bound states of this theory are very `` qcd - like . ''
the wave functions of some of the low mass states have a striking valence structure .
we present the valence and sea parton structure functions of these states .
in addition , we identify bps - like states which are almost independent of the coupling .
their masses are proportional to their parton number in the large - coupling limit . .
And you have already written the first three sentences of the full article: chern simons ( cs ) theories are certainly some of the most interesting field theories in 2 + 1 dimensions . among the interesting phenomena one sees in these theories
are : the quantum hall effect , landau levels , non - trivial topological structures , vortices , and anyons . for a review of these phenomena
see @xcite ..
Please generate the next two sentences of the article | some of these ( 2 + 1)-dimensional phenomena have been observed experimentally in condensed matter systems .
cs theories are also often described as topological theories @xcite since for most gauge groups the cs coupling must obey a quantization condition for the theory to remain gauge invariant . within this rich literature on cs theories |
8,964 | Suppose that you have an abstract for a scientific paper: we investigate the caesium concentrations in soils in mountain areas near gori nuclear power plant in korea , focusing on the measurement limits to the @xmath0 . in order to lower the minimum detectable amount ( mda ) of activity for the @xmath0
, we have used the ammonium molybdophosphase ( amp ) precipitation method to get rid of the @xmath1k existing in natural radioactivity , which reduces the mda of activity about ten times smaller than those without the amp precipitation method .
the mda results for the @xmath0 were found to be in the range between @xmath2 and @xmath3 bq / kg - dry weight . in order to diminish the background ,
we also have measured a part of the soil samples in yangyang , a small town in the east coast of korea .
however , it turns out that in order to detect the @xmath0 in the samples the mda should be reduced to the level of mbq / kg - dry weight .
@xmath4cs , @xmath5cs , ammonium molybdophosphate ( amp ) precipitation method , minimum detectable amount ( mda ) .
And you have already written the first three sentences of the full article: it is of great importance to study the anthropogenic caesium radioisotopes @xmath6 and @xmath0 , since their production and emission rates are much higher than other radioisotopes from nuclear fissions at nuclear power plants ( npp ) and they have rather low movility in soils .
thus , @xmath5cs are widely used as tracer radionuclides for monitoring the npp - related environmental radioactivity . the @xmath5cs nucleus ( @xmath7y )
is a long - lived beta emitter decaying a @xmath8 branching ratio to the metastable state ( @xmath9 m ) of @xmath5ba@xmath10 at 661.7kev ..
Please generate the next two sentences of the article | while the @xmath4cs nucleus is also a beta emitter , its decay time ( @xmath11y ) is much shorter and emits many gamma - rays correlated with the beta electron . due to these different life - times ,
it is possible to date the anthropogenic radioactivity with the ratio of @xmath4cs to @xmath5cs concentrations in soil measured . |
8,965 | Suppose that you have an abstract for a scientific paper: we establish a cheeger - mller theorem for unimodular representations satisfying a witt condition on a noncompact manifold with cusps .
this class of spaces includes all non - compact hyperbolic spaces of finite volume , but we do not assume that the metric has constant curvature nor that the link of the cusp is a torus .
we use renormalized traces in the sense of melrose to define the analytic torsion and we relate it to the intersection r - torsion of dar of the natural compactification to a stratified space .
our proof relies on our recent work on the behavior of the hodge laplacian spectrum on a closed manifold undergoing degeneration to a manifold with fibered cusps . .
And you have already written the first three sentences of the full article: the celebrated theorem of cheeger and mller establishes the equality of reidemeister and analytic torsion on an odd - dimensional closed manifold equipped with a flat euclidean bundle .
this was originally conjectured by ray - singer @xcite , proven by cheeger and mller @xcite and subsequently extended by mller @xcite and bismut - zhang @xcite .
the importance and usefulness of the theorem stems from the fact that the reidemeister torsion , or r - torsion , is a combinatorial invariant of simplicial complexes while the analytic torsion is a smooth invariant defined via the spectrum of the hodge laplacian ..
Please generate the next two sentences of the article | this connection is behind many applications in topology , number theory , and mathematical physics .
one particularly interesting aspect of this theorem is that it allows us to use analysis to study the size of the torsion in cohomology . |
8,966 | Suppose that you have an abstract for a scientific paper: we study the effects of the interaction between the chiral condensate and the polyakov loop on the chiral transition within an effective lagrangian .
we find that the effects of the interaction change the order of the phase transition when the explicit breaking of the @xmath0 symmetry of the polyakov loop is large .
our results suggest that the chiral transition in 2-flavor qcd may be first order . .
And you have already written the first three sentences of the full article: qcd matter with @xmath1 flavors , @xmath2 colors and zero baryon chemical potential undergoes two finite temperature phase transitions , the chiral transition and the deconfinement .
the chiral transition is associated with the spontaneous breaking of the chiral symmetry , @xmath3 , below the critical temperature ( @xmath4 ) for massless quarks .
the order parameter for this transition is the chiral condensate . on the other hand.
Please generate the next two sentences of the article | the deconfinement transition is associated with the spontaneous symmetry breaking , @xmath5 , above the critical temperature @xmath6 for infinitely heavy quarks .
the order parameter for this transition is the polyakov loop expectation value . for finite non - zero quark masses |
8,967 | Suppose that you have an abstract for a scientific paper: an energetic argument implies that a galaxy like the milky way is blowing a powerful wind that carries away most of the heavy elements currently synthesized and has impacted the igm out to at least @xmath0 .
rich clusters of galaxies appear to be closed systems in which most heavy elements are ejected from galaxies .
more supernovae are required than the yield of core - collapse sne from a salpeter imf .
x - ray observations imply that the igm in groups and clusters as been strongly preheated .
sne probably can not supply the required energy , which must come from agn . .
And you have already written the first three sentences of the full article: observations of both cool and hot intergalactic gas make it clear that heavy elements are by no means confined to galaxies .
larson ( 1974 ) predicted that late in the galaxy formation process , galactic winds would carry heavy elements out into intergalactic space .
soon afterwards x - ray spectra of intracluster gas confirmed that the gas was quite metal - rich . in recent years observations of absorption lines in qso spectra.
Please generate the next two sentences of the article | have elucidated the impact of supernovae on the diffuser gas that is found in the field , at least at high redshift .
these observations imply that , from a redshift @xmath1 onwards , there does not seem to be a parcel of gas that has not felt the impact of spernovae , probably mediated by galactic winds . while the ubiquity of the products of supernovae is beyond doubt , many aspects of the interaction of supernovae and intergalactic gas are highly uncertain . |
8,968 | Suppose that you have an abstract for a scientific paper: a general method for the direct evaluation of the temperature dependence of the quantum - mechanical reaction rate constant in many - dimensional systems is described .
the method is based on the quantum instanton approximation for the rate constant , thermodynamic integration with respect to the inverse temperature , and the path integral monte carlo evaluation .
it can describe deviations from the arrhenius law due to the coupling of rotations and vibrations , zero - point energy , tunneling , corner - cutting , and other nuclear quantum effects .
the method is tested on the eckart barrier and the full - dimensional h @xmath0h@xmath1 h@xmath2 h reaction . in the temperature range from @xmath3 to @xmath4 ,
the error of the present method remains within @xmath5 despite the very large deviations from the arrhenius law .
the direct approach makes the calculations much more efficient , and the efficiency is increased even further ( by up to two orders of magnitude in the studied reactions ) by using optimal estimators for reactant and transition state thermal energies .
which of the estimators is optimal , however , depends on the system and the strength of constraint in a constrained simulation . .
And you have already written the first three sentences of the full article: the measurement of the temperature dependence of the rate constant is one of the important tools of chemical kinetics in determining mechanisms of chemical reactions.@xcite significant deviations from a simple exponential behavior can be evidence of tunneling and of other nuclear quantum effects.@xcite these effects are particularly strong for hydrogen transfer reactions with a high activation barrier or at low temperatures .
recently , however , quantum effects have been observed also in many enzymatic reactions at physiological temperatures.@xcite it therefore becomes more and more important to have accurate theoretical methods for computing the temperature dependence of the rate constant.@xcite probably the oldest yet still the best known expression for the thermal rate constant @xmath6 at temperature @xmath7 is the empirical arrhenius law,@xcite@xmath8 here @xmath9 is the boltzmann constant , @xmath10 the activation energy , and the temperature dependence is purely exponential .
an improvement over the arrhenius law was provided by the transition state theory ( tst),@xcite in which @xmath11 where @xmath12 is the planck s constant , @xmath13 and @xmath14 are the partition functions of the transition state and the reactants , respectively , and @xmath15 is the barrier height for the reaction . here.
Please generate the next two sentences of the article | the temperature dependence includes a fractional power @xmath16 in addition to the exponential .
nevertheless , both arrhenius law and tst are basically purely classical , so they can not take into account tunneling and other nuclear quantum effects . |
8,969 | Suppose that you have an abstract for a scientific paper: a quaternionic version of quantum mechanics is constructed using the schwinger formulation based on measurements and a variational principle .
commutation relations and evolution equations are provided , and the results are compared with other formulations . .
And you have already written the first three sentences of the full article: in 1936 birkhoff and von neumann @xcite have shown the existence of a propositional calculus as fundamental ingredient of quantum mechanics ( qm ) , which could be written using only the outputs of measures .
it does not assume any set of numbers or even a particular vectorial space , but contains the essentials of qm such as uncertainty relations and complementary properties .
of course , the authors showed that there are three different realizations for this propositional calculus , corresponding to the real or complex numbers or still quaternions ..
Please generate the next two sentences of the article | octonions and higher dimensional extensions of the complex numbers are discarded , since they can not have a conservation law for the probability current @xcite .
we can ask : which of these three realizations of the general qm of birkhoff and von neumann is present in nature ? |
8,970 | Suppose that you have an abstract for a scientific paper: we propose a method for eliminating the truncation error associated with any subspace diagonalization calculation .
the new method , called stochastic error correction , uses monte carlo sampling to compute the contribution of the remaining basis vectors not included in the initial diagonalization .
the method is part of a new approach to computational quantum physics which combines both diagonalization and monte carlo techniques . .
And you have already written the first three sentences of the full article: in @xcite a new approach was proposed for finding the low - energy eigenstates of very large or infinite - dimensional quantum hamiltonians .
this proposal combines both diagonalization and monte carlo methods , each being used to solve a portion of the problem for which the technique is most efficient .
the first part of the proposal is to diagonalize the hamiltonian restricted to a subspace containing the most important basis vectors for each low energy eigenstate ..
Please generate the next two sentences of the article | this may be accomplished either through variational techniques or an _ ab initio _ method such as quasi - sparse eigenvector ( qse ) diagonalization .
the second step is to include the contribution of the remaining basis vectors by monte carlo sampling . |
8,971 | Suppose that you have an abstract for a scientific paper: starting with a zipoy - voorhees line element we construct and study the three parameter family of solutions describing a deformed black string with arbitrary tension . .
And you have already written the first three sentences of the full article: associated with string theory and higher dimensional universes , there has been a renewed interest in higher dimensional solutions to einstein field equations , among the most interesting being black rings @xcite , kk bubbles as well as black strings .
one simple way to lift the 4d schwarzschild black hole to a 5d black string is to add an extra flat dimension . in other words
it is possible to uniformly extend the 4d black hole with @xmath0 horizon into the fifth dimension producing a hypercylindrical black hole @xmath1 @xcite . a striking fact related to black strings is their generic instability and final fate and whether these end up as black holes or different objects is still not well understood @xcite , @xcite . in this sense.
Please generate the next two sentences of the article | it is interesting testing more general black string solutions both static and non - static .
some generalizations are obtained by applying a boost to the string solution , dotating the string with the momentum along the fifth coordinate @xcite . in this work |
8,972 | Suppose that you have an abstract for a scientific paper: recently han and heary proposed an approach to steady - state quantum transport through mesoscopic structures , which maps the non - equilibrium problem onto a family of auxiliary quantum impurity systems subject to imaginary voltages .
we employ continuous - time quantum monte - carlo solvers to calculate accurate imaginary time data for the auxiliary models .
the spectral function is obtained from a maximum entropy analytical continuation in both matsubara frequency and complexified voltage . to enable the analytical continuation
we construct a kernel which is compatible with the analytical structure of the theory .
while it remains a formidable task to extract reliable spectral functions from this unbiased procedure , particularly for large voltages , our results indicate that the method in principle yields results in agreement with those obtained by other methods . .
And you have already written the first three sentences of the full article: the calculation of steady - state transport properties of open quantum systems such as quantum dots is a challenging and unsolved problem .
perturbative methods @xcite may be used to study the weak correlation regime , but they fail to provide a reliable description of the competition between kondo- and coulomb - blockade physics in strongly interacting dots @xcite . to avoid these limitations of conventional perturbation theory ,
various non - perturbative numerical approaches have been developed ..
Please generate the next two sentences of the article | time - dependent density - matrix renormalization group ( tdmrg ) calculations @xcite and real - time monte carlo ( rt - mc ) approaches @xcite try to compute the relaxation into the interacting steady state after some switching of parameters , such as voltage bias or interaction . while the short - time transients can be very accurately captured with these methods @xcite , the approach to the steady - state may occur on rather long , in the worst case exponentially large times scales . due to finite - size effects in the tdmrg and an exponentially growing sign problem with increasing time in rt - mc , the access to long times
is severely limited in both approaches . |
8,973 | Suppose that you have an abstract for a scientific paper: in this research we address the problem of capturing recurring concepts in a data stream environment .
recurrence capture enables the re - use of previously learned classifiers without the need for re - learning while providing for better accuracy during the concept recurrence interval .
we capture concepts by applying the discrete fourier transform ( dft ) to decision tree classifiers to obtain highly compressed versions of the trees at concept drift points in the stream and store such trees in a repository for future use .
our empirical results on real world and synthetic data exhibiting varying degrees of recurrence show that the fourier compressed trees are more robust to noise and are able to capture recurring concepts with higher precision than a meta learning approach that chooses to re - use classifiers in their originally occurring form . .
And you have already written the first three sentences of the full article: data stream mining has been the subject of extensive research over the last decade or so
. one of the major issues with data stream mining is dealing with concept drift that causes models built by classifiers to degrade in accuracy over a period of time . while data steam environments require that models are updated to reflect current concepts , the capture and storage of recurrent concepts allows a classifier to use an older version of the model that provides a better fit with newly arriving data in place of the current model .
this approach removes the need to explicitly re - learn the model , thus improving both accuracy and computational cost ..
Please generate the next two sentences of the article | a number of methods have been proposed that deal with the capture and exploitation of recurring concepts @xcite , @xcite , @xcite , @xcite and @xcite .
although achieving higher accuracy as expected during phases of concept recurrence in the stream , a major issue with existing approaches is the setting of user defined parameters to determine whether a current concept matches with one from the past . |
8,974 | Suppose that you have an abstract for a scientific paper: this paper studies a markov chain for phylogenetic reconstruction which uses a popular transition between tree topologies known as subtree pruning - and - regrafting ( spr ) .
we analyze the markov chain in the simpler setting that the generating tree consists of very short edge lengths , short enough so that each sample from the generating tree ( or character in phylogenetic terminology ) is likely to have only one mutation , and that there enough samples so that the data looks like the generating distribution .
we prove in this setting that the markov chain is rapidly mixing , i.e. , it quickly converges to its stationary distribution , which is the posterior distribution over tree topologies .
our proofs use that the leading term of the maximum likelihood function of a tree @xmath0 is the maximum parsimony score , which is the size of the minimum cut in @xmath0 needed to realize single edge cuts of the generating tree .
our main contribution is a combinatorial proof that in our simplified setting , spr moves are guaranteed to converge quickly to the maximum parsimony tree .
our results are in contrast to recent works showing examples with heterogeneous data ( namely , the data is generated from a mixture distribution ) where many natural markov chains are exponentially slow to converge to the stationary distribution . .
And you have already written the first three sentences of the full article: we study markov chain monte carlo ( mcmc ) methods for bayesian inference of phylogeny .
we begin by presenting the relevant background material by defining phylogenetic trees , evolutionary models ( in section [ sec : evolutionary - models ] ) , and the associated mcmc methods ( in section [ sec : spr ] ) .
we refer the interested reader to semple and steel @xcite for a more comprehensive introduction to the mathematics of phylogeny . finally , we present our results and discuss related work in section [ sec : our - results ] ..
Please generate the next two sentences of the article | a phylogenetic tree is an unrooted tree @xmath0 on @xmath1 leaves ( called taxa , corresponding to @xmath1 species ) where internal vertices have degree three .
let @xmath2 denote the edges of @xmath0 and @xmath3 denote the vertices . in the phylogenetic reconstruction problem |
8,975 | Suppose that you have an abstract for a scientific paper: the motivation of this work is to improve the performance of standard stacking approaches or ensembles , which are composed of simple , heterogeneous base models , through the integration of the generation and selection stages for regression problems .
we propose two extensions to the standard stacking approach . in the first extension
we combine a set of standard stacking approaches into an ensemble of ensembles using a two - step ensemble learning in the regression setting .
the second extension consists of two parts . in the initial part
a diversity mechanism is injected into the original training data set , systematically generating different training subsets or partitions , and corresponding ensembles of ensembles . in the final part after measuring the quality of the different partitions or ensembles , a max - min rule - based selection algorithm is used to select the most appropriate ensemble / partition on which to make the final prediction .
we show , based on experiments over a broad range of data sets , that the second extension performs better than the best of the standard stacking approaches , and is as good as the oracle of databases , which has the best base model selected by cross - validation for each data set .
in addition to that , the second extension performs better than two state - of - the - art ensemble methods for regression , and it is as good as a third state - of - the - art ensemble method .
* keywords : * ensemble learning , stacked generalization , systematic cross - validation , ensemble selection , regression , max - min based rules . .
And you have already written the first three sentences of the full article: recent developments in the machine learning community have brought innovative ideas and methods to solve problems in data mining and predictive analytics with important applications in the business world such as credit risk , fraud detection , survey direct response , customer segmentation , etc .. among such methodologies ensemble learning has been an active research area within the last two decades , where it is believed that combining the predictions of different models or base models , e.g. , by weighted averaging , can bring an improvement in the prediction error in comparison to the error provided by the best individual model or base model .
alternative ways that we will be using throughout the paper to refer to base models are base learner , level-0 learner or level-0 models .
the setting of the approximation for regression we are considering is in the context of supervised learning : given an historical dataset @xmath0 with @xmath1 training samples @xmath2 , @xmath3 , where @xmath4 , and @xmath5 is a stochastic error , the task is to approximate the unknown function @xmath6 by @xmath7 , so we fit a model @xmath8 to the training data by minimizing the square error @xmath9 interested readers can consult @xcite and @xcite for a deeper discussion about this topic ..
Please generate the next two sentences of the article | the aim of this work is to approximate the unknown function @xmath10 using a linear combination of base learners , or learning algorithms .
so , instead of a single estimator @xmath7 we have a collection of them ; @xmath11 . |
8,976 | Suppose that you have an abstract for a scientific paper: we present the main results of a study of time - resolved spectra of 43 intense grbs detected by batse .
we considered the 4-parameter band model and the optically thin synchrotron shock model ( otssm ) .
we find that the large majority of time - resolved spectra of grbs are in remarkable agreement with the otssm .
however , about 15 % of _ initial grb pulses _ show an apparent low - energy photon suppression .
this phenomenon indicates that complex radiative conditions modifying optically thin emission may occur during the initial phases of some grbs . .
And you have already written the first three sentences of the full article: we study a sample of 43 grbs selected for the high - quality of their time - resolved spectra obtained with the batse spectroscopy detectors ( sensitive in the energy range @xmath0 kev ) .
the time over which each spectrum was accumulated was varied so that the signal - to - noise ratio was greater than 15 ( in the hard x - ray energy band ) .
these data provide excellent temporal resolution : in many cases we obtain more than 10 spectra per burst with accumulation times as short as 256 ms ..
Please generate the next two sentences of the article | we fitted each grb time - resolved spectrum with two models : ( 1 ) the band model [ 1 ] , and ( 2 ) the optically thin synchrotron shock model ( otssm ) @xcite . the ( purely phenomenological ) 4-parameter band model @xcite consists of two power - law components ( of spectral indexes @xmath1 and @xmath2 ) joined smoothly by an exponential roll - over near a break energy @xmath3 .
@xmath4 \left(\frac{e}{{\rm 100 \ , kev } } \right)^\beta \ ; \ ; \ ; { \rm for } \;\ ; e \geq \left ( \alpha - \beta \right ) e_{0 } \end{aligned}\ ] ] we used the ( three - parameter ) otssm of refs . |
8,977 | Suppose that you have an abstract for a scientific paper: we investigate a biologically motivated approach to fast visual classification , directly inspired by the recent work @xcite . specifically , trading - off biological accuracy for computational efficiency , we explore using wavelet and grouplet - like transforms to parallel the tuning of visual cortex v1 and v2 cells , alternated with max operations to achieve scale and translation invariance .
a feature selection procedure is applied during learning to accelerate recognition .
we introduce a simple attention - like feedback mechanism , significantly improving recognition and robustness in multiple - object scenes . in experiments ,
the proposed algorithm achieves or exceeds state - of - the - art success rate on object recognition , texture and satellite image classification , language identification and sound classification . .
And you have already written the first three sentences of the full article: automatic object recognition and image classification are important and challenging tasks .
this paper is inspired by the remarkable recent work of poggio , serre , and their colleagues @xcite , on rapid object categorization using a feedforward architecture closely modeled on the human visual system .
the main directions it departs from that work are twofold ..
Please generate the next two sentences of the article | first , trading - off biological accuracy for computational efficiency , our results exploit more engineering - motivated mathematical tools such as wavelet and grouplet transforms @xcite , allowing faster computation and limiting ad - hoc parameters .
second , the approach is generalized by adding a degree of _ feedback _ ( another known component of human perception ) , yielding significant performance and robustness improvement in multiple - object scenes . in experiments , |
8,978 | Suppose that you have an abstract for a scientific paper: we present a systematic search for ovi(1032,1037 ) absorption in a keck hires spectrum of the @xmath0 quasar q1422 + 231 , with the goal of constraining the metallicity and ionization state of the low density intergalactic medium ( igm ) .
comparison of civ absorption measurements to models of the ly@xmath1 forest based on cosmological simulations shows that absorbers with @xmath2 have a mean carbon abundance [ c / h ] @xmath3 , assuming a metagalactic photoionizing background with the spectral shape predicted by haardt & madau ( 1996 , hm ) . in these models , lower column density absorption arises in lower density gas where most civ is photoionized to cv .
therefore , ovi should be the most sensitive tracer of metallicity in ly@xmath1 absorbers with @xmath4 .
ovi lines lie at wavelengths heavily contaminated by lyman series absorption , so we interpret the search results by comparing to carefully constructed , mock q1422 spectra drawn from a hydrodynamic simulation of a @xmath5-dominated cold dark matter model . a search for deep , narrow absorption features yields only a few candidate ovi lines in the spectrum of q1422 .
hi absorption blankets the position of the doublet companion line in each case , and the total number of narrow lines is statistically consistent with that in zero - metallicity artificial spectra .
artificial spectra generated with the hm background and [ o / h ] @xmath6 predict too many narrow lines and are statistically inconsistent with the data .
we also search for ovi associated with civ systems , using the optical depth ratio technique of songaila ( 1998 ) . with this method
we _ do _ find significant ovi absorption ; matching the data requires [ o / c ] @xmath7 and corresponding [ o / h ] @xmath8 .
taken together , the narrow line and optical depth ratio results imply that ( a ) the metallicity in the low density regions of the igm is at least a factor of three below that in the overdense regions where civ absorption is detectable , and ( b ) oxygen is....
And you have already written the first three sentences of the full article: the lyman alpha ( ly@xmath1 ) forest " ( @xcite ; @xcite ) of spectral features caused by hi absorption along the line of sight to a quasar probes the state of the intergalactic medium over a wide range of physical conditions . during the past few years
, high - precision observations made using the hires spectrograph ( @xcite ) on the 10 m keck telescope have quantified the statistics of these low column density absorbers to unprecedented accuracy ( e.g. , @xcite ; @xcite ; @xcite ; @xcite ) . during the same time span ,
cosmological simulations that incorporate gas dynamics , radiative cooling , and photoionization have been able to reproduce many of the observed properties of quasar absorption spectra ( @xcite ; @xcite ; @xcite ; @xcite ; @xcite ) ..
Please generate the next two sentences of the article | the rapid progress on theoretical and observational fronts has led to the emergence of a new paradigm for the origin of the high - redshift ( @xmath12 ) ly@xmath1 forest , in which most ly@xmath1 forest lines are produced by regions of low to moderate overdensity in hierarchically collapsing structures that are not in dynamical or thermal equilibrium .
ly@xmath1 lines of lower column density generally arise in gas of lower physical density , which has a lower neutral hydrogen fraction because of the reduced recombination rate . in this paper , we use a matched comparison between a cosmological hydrodynamic simulation and a keck hires spectrum of the quasar q1422 + 231 to constrain the metal abundance of this low density gas . the recent detection of metal lines associated with ly@xmath1 forest absorbers having column densities @xmath13 ( @xcite ; @xcite ; songaila & cowie 1996 , hereafter @xcite ) has provided a new avenue for investigating the ionization state and enrichment history of the high - redshift intergalactic medium ( igm ) . |
8,979 | Suppose that you have an abstract for a scientific paper: we study several different @xmath0 topological ordered states in frustrated spin systems .
the effective theories for those different @xmath0 topological orders all have the same form a @xmath0 gauge theory which can also be written as a mutual @xmath1 chern - simons theory .
however , we find that the different @xmath0 topological orders are reflected in different projective realizations of lattice symmetry in the same effective mutual chern - simons theory .
this result is obtained by comparing the ground - state degeneracy , the ground - state quantum numbers , the gapless edge state , and the projective symmetry group of quasi - particles calculated from the slave - particle theory and from the effective mutual chern - simons theories .
our study reveals intricate relations between topological order and symmetry .
keywords : topological order , mutual chern - simons theory , spin liquid .
And you have already written the first three sentences of the full article: after the discovery of fractional quantum hall effect,@xcite , we realized that new kind of orders beyond landau s symmetry breaking paradigm is possible .
this new kind order is called topological order @xcite for gapped states and quantum order@xcite for general states .
the new orders reflect patterns of long range entanglements in the ground state . gapped @xmath0 spin liquids have the simplest kind of topological order .
Please generate the next two sentences of the article | @xmath0 topological order.@xcite those topological ordered states may appear in frustrated spin systems or dimmer models.@xcite physically , the topological orders can be ( partially ) characterized by robust ground - state degeneracy.@xcite the low energy effective theory for those @xmath0 topologically ordered states is a @xmath0 gauge theory .
topological order is a property of a many - body ground state that is robust against any perturbations , even those perturbations that break all the symmetries . in this paper , we like to study the interplay between topological order and symmetry . |
8,980 | Suppose that you have an abstract for a scientific paper: we consider 1d burgers equation driven by large - scale white - in - time random force .
the tails of the velocity gradients probability distribution function ( pdf ) are analyzed by saddle - point approximation in the path integral describing the velocity statistics .
the structure of the saddle - point ( instanton ) , that is velocity field configuration realizing the maximum of probability , is studied numerically in details .
the numerical results allow us to find analytical solution for the long - time part of the instanton .
its careful analysis confirms the result of [ phys .
. lett . * 78 * , 1452 ( 1997 ) ] based on short - time estimations that the left tail of pdf has the form @xmath0 .
pacs numbers : 47.27.gs , 05.10.-a 2 .
And you have already written the first three sentences of the full article: we consider the random forced burgers equation @xmath1 that describes weak 1d acoustic perturbations in the reference frame moving with the sound velocity @xcite .
the external force @xmath2 in this frame is generally short - correlated in time , so let us assume that @xmath3 then the statistics of @xmath2 can be thought gaussian and therefore is completely characterized by ( [ phipc ] ) .
we are interested in turbulence with a large value of reynolds number @xmath4 , where @xmath5 is the characteristic scale of the stirring force correlator @xmath6 ..
Please generate the next two sentences of the article | this problem was intensively studied during the last years @xcite .
the main feature of burgers turbulence is the formation of shock waves with large negative velocity gradient inside and small viscous width of the front . |
8,981 | Suppose that you have an abstract for a scientific paper: complex systems made of interacting elements are commonly abstracted as networks , in which nodes are associated with dynamic state variables , whose evolution is driven by interactions mediated by the edges .
markov processes have been the prevailing paradigm to model such a network - based dynamics , for instance in the form of random walks or other types of diffusions . despite the success of this modelling perspective for numerous applications
, it represents an over - simplification of several real - world systems .
importantly , simple markov models lack memory in their dynamics , an assumption often not realistic in practice . here , we explore possibilities to enrich the system description by means of second - order markov models , exploiting empirical pathway information .
we focus on the problem of community detection and show that standard network algorithms can be generalized in order to extract novel temporal information about the system under investigation .
we also apply our methodology to temporal networks , where we can uncover communities shaped by the temporal correlations in the system .
finally , we discuss relations of the framework of second order markov processes and the recently proposed formalism of using non - backtracking matrices for community detection . .
And you have already written the first three sentences of the full article: dynamics on complex networks , such as the diffusion of information in a social networks , are commonly modelled as markov processes .
an advantage of this approach is that for every ( static ) network with positive edge - weights we can define a corresponding markov process by interpreting the network as the state space of a random walker , and assigning the state - transition probabilities according to the link weights .
this direct correspondence between the state space of the markov process and the network enables us to examine the interplay between structure and dynamics from two sides . on the one hand.
Please generate the next two sentences of the article | , one can assess how the topological properties of a network influence the dynamical process .
on the other hand , this coupling between topology and dynamics allows us to explore the structure of a network by means of a dynamical process . |
8,982 | Suppose that you have an abstract for a scientific paper: black hole mass , along with mass accretion rate , is a fundamental property of active galactic nuclei .
black hole mass sets an approximate upper limit to agn energetics via the eddington limit .
we collect and compare all agn black hole mass estimates from the literature ; these 177 masses are mostly based on the virial assumption for the broad emission lines , with the broad - line region size determined from either reverberation mapping or optical luminosity .
we introduce 200 additional black hole mass estimates based on properties of the host galaxy bulges , using either the observed stellar velocity dispersion or using the fundamental plane relation to infer @xmath0 ; these methods assume that agn hosts are normal galaxies .
we compare 36 cases for which black hole mass has been generated by different methods and find , for individual objects , a scatter as high as a couple of orders of magnitude .
the less direct the method , the larger the discrepancy with other estimates , probably due to the large scatter in the underlying correlations assumed .
using published fluxes , we calculate bolometric luminosities for 234 agns and investigate the relation between black hole mass and luminosity .
in contrast to other studies , we find no significant correlation of black hole mass with luminosity , other than those induced by circular reasoning in the estimation of black hole mass .
the eddington limit defines an approximate upper envelope to the distribution of luminosities , but the lower envelope depends entirely on the sample of agn included . for any given black hole mass
, there is a range in eddington ratio of up to three orders of magnitude . .
And you have already written the first three sentences of the full article: black holes have been the leading candidate to power the central engines in agn for over three decades ( lynden - bell 1969 ) , but direct evidence for their presence has been elusive . in nearby galaxies ,
spatially resolved kinematics have provided strong evidence for the ubiquity of nuclear black holes , with dynamical black hole detections reported for 37 galaxies ( kormendy & gebhardt 2001 ) .
such observations are available only for a handful of the nearest agn ( harms et al ..
Please generate the next two sentences of the article | 1994 , miyoshi et al .
1995 , greenhill et al . |
8,983 | Suppose that you have an abstract for a scientific paper: while several arguments can be proposed against the existence of particles with energy in excess of @xmath0 ev in the cosmic ray spectrum , these particles are actually observed and their origin seeks for an explanation . after a description of the problems encountered in explaining these ultra - high energy cosmic rays ( uhecrs ) in the context of astrophysical sources , we will review the so - called _ top - down _ ( td ) models , in which uhecrs are the result of the decay of very massive unstable particles , possibly created in the early universe .
particular emphasis will be given to the signatures of the td models , likely to be accessible to upcoming experiments like auger .
= -1.2truecm = -2.5truecm = cmbx10 = cmr10 = cmti10 = cmbx10 scaled1 = cmr10 scaled1 = cmti10 scaled1 = cmbx9 = cmr9 = cmti9 = cmbx8 = cmr8 = cmti8 = cmr7 = cmti7 * opening the ultra high energy cosmic ray window * * from the top * pasquale blasi nasa / fermilab astrophysics center fermi national accelerator laboratory , box 500 , batavia , il 60510 - 0500 .
And you have already written the first three sentences of the full article: cosmic ray particles with energy in excess of @xmath1 ev have been detected during the last thirty years by several independent experiments , such as agasa ( takeda et al .
1998 ; takeda et al . 1999
; hayashida et al . 1994 ) , fly s eye ( bird et al ..
Please generate the next two sentences of the article | 1993 , 1994 , 1995 ) , haverah park ( lawrence , reid and watson 1991 ) , yakutsk ( efimov 1991 ) , volcano ranch ( linsley 1963 ) and more recently by the high resolution fly s eye experiment ( kieda et al .
these events represent now more than ever a big challenge for our understanding of particle physics and astrophysics . while hystorically the first reactions to the detection of these particles were related to the already difficult problem of accelerating particles to the highest observed energies , it became soon clear that the existence of cosmic rays having energy larger than @xmath2 ev [ the so - called ultra - high energy cosmic rays ( uhecr ) ] was more than that , and indeed represented a much more serious challenge to known physics . |
8,984 | Suppose that you have an abstract for a scientific paper: we show in this letter that relativistic dragging of inertial frames around fast rotating collapsed stars is substantial and can give rise to observable effects .
we apply this to the khz quasi periodic oscillations ( qpos ) sources , low mass x - ray binaries ( lmxrbs ) containing an accreting neutron star . within the beat frequency model , both the keplerian frequency of the innermost region of the accretion disk ( @xmath0 khz ) and the neutron star spin frequency ( @xmath1 khz )
are directly observed . from these the lense - thirring precession frequency ( tens of hz ) of the same material in the innermost disk regions which gives rise to the khz qpos is determined within a factor of @xmath2 , depending on the neutron star equation of state . the classical contribution from neutron star oblateness decreases the precession frequency slightly .
the broad peaks at frequencies @xmath3 hz in the power spectra of the atoll "- sources 4u 1728 - 34 , 4u 0614 + 091 and ks 1731 - 260 and their variations with the higher khz qpo frequency are well matched by lense - thirring precession of material in the innermost disk region .
we also suggest that the @xmath4 hz horizontal branch qpos of gx 5 - 1 and gx 17 + 2 ( and likewise other z "- type low mass x - ray binaries ) arise from the same mechanism . -1.2 cm 24.0 cm 17.cm -.5 cm .
And you have already written the first three sentences of the full article: the variety of qpo modes from old accreting neutron stars in low mass x - ray binaries ( lmxrbs ) ( see van der klis 1995 ) has been recently enriched by the discovery of kilohertz oscillations in light curves obtained with the rossi x - ray timing explorer ( rxte ) .
these are the first qpos that involve timescales comparable to the dynamical timescales in the vicinity of a collapsed star .
there are currently eleven lmxrbs from which qpos have been detected between frequencies of @xmath5 and @xmath6 khz ..
Please generate the next two sentences of the article | most of these are type i x - ray bursters with persistent luminosities in the @xmath7 ergs s@xmath8 range , that according to the classification of hasinger and van der klis ( 1989 ) either belong to ( 4u 1728 - 34 , 4u 1608 - 52 , 4u 1636 - 536 , 4u 1735 - 444 and 4u 1820 - 30 ) or are suspected members of ( 4u 0614 + 091 and ks 1731 - 260 ) the atoll " group .
sco x-1 , gx 5 - 1 and gx 17 + 2 are instead high luminosity z "- type lmxrbs . |
8,985 | Suppose that you have an abstract for a scientific paper: the shear - transformation - zone ( stz ) theory has been remarkably successful in accounting for broadly peaked , frequency - dependent , viscoelastic responses of amorphous systems near their glass temperatures @xmath0 .
this success is based on the theory s first - principles prediction of a wide range of internal stz transition rates .
here , i show that the stz rate - distribution causes the newtonian viscosity to be strongly temperature dependent ; and i propose that it is this temperature dependence , rather than any heterogeneity - induced enhancement of diffusion , that is responsible for stokes - einstein violations near @xmath0 .
i also show that stretched - exponential relaxation of density fluctuations emerges naturally from the same distribution of stz transition rates that predicts the viscoelastic behavior . to be consistent with observations of fickian diffusion near @xmath0 , however , an stz - based diffusion theory somehow must include the cascades of correlated displacement events that are seen in low - temperature numerical simulations . .
And you have already written the first three sentences of the full article: among the deepest challenges in glass physics is understanding the temperature dependence of the stokes - einstein ratio in the neighborhood of the glass temperature @xmath0 @xcite .
an apparently related phenomenon is the stretched - exponential relaxation of density fluctuations and other correlations .
both phenomena have been cited as evidence for dynamic heterogeneities @xcite , which supposedly provide rapid diffusion paths relevant to the first case , and a variety of localized , relaxation environments in the second @xcite ..
Please generate the next two sentences of the article | here , i offer a counterproposal that these phenomena can be explained more systematically by the multi - species shear - transformation - zone ( stz ) theory that bouchbinder and i @xcite invoked to understand the broad range of time scales observed in viscoelastic experiments .
a short account of this proposal has appeared in @xcite . |
8,986 | Suppose that you have an abstract for a scientific paper: a method is presented to derive electron temperatures and densities of planetary nebulae ( pne ) simultaneously , using the observed hydrogen recombination spectrum , which includes continuum and line emission . by matching theoretical spectra to observed spectra around the balmer jump at about 3646
, we determine electron temperatures and densities for 48 galactic pne .
the electron temperatures based on this method [ hereafter @xmath0(bal ) ] are found to be systematically lower than those derived from [ ] @xmath1 and [ ] @xmath2 ratios [ hereafter , @xmath0([]@xmath3 ) and @xmath0([]@xmath4 ) ] . and
the electron densities based on this method are found to be systematically higher than those derived from [ ] @xmath5 , [ ] @xmath6 , [ ] @xmath7 , [ ] @xmath8 and [ ] @xmath9 ratios .
these results suggest that temperature and density fluctuations are generally present within nebulae .
the comparison of @xmath0([]@xmath3 ) and @xmath0(bal ) suggests that the fractional mean - square temperature variation ( @xmath10 ) has a representative value of 0.031 .
a majority of temperatures derived from the [ ] @xmath2 ratio are found to be higher than @xmath0([]@xmath3 ) , which is attributed to the existence of dense clumps in nebulae those [ ] ir fine - structure lines are suppressed by collisional de - excitation in the clumps . by comparing @xmath0([]@xmath4 ) , @xmath0([]@xmath3 ) and @xmath0(bal ) and assuming a simple two - density - component model , we find that the filling factor of dense clumps has a representative value of 7@xmath11 . the discrepancies between @xmath0([]@xmath3 ) and @xmath0(bal ) are found to be anti - correlated with electron densities derived from various density indicators ; high - density nebulae have the smallest temperature discrepancies .
this suggests that temperature discrepancy is related to nebular evolution .
in addition , he / h abundances of pne are found to be positively correlated with the difference between @xmath0([]@xmath3 ) and @xmath0(bal ) ,....
And you have already written the first three sentences of the full article: accurate determinations of metal abundances in planetary nebulae ( pne ) are important for understand the chemical evolution of galaxies and the nucleosynthesis and mixing processes in low- and intermediate - mass stars . a long - standing problem in nebular abundance studies
has been that the heavy - element abundances derived from optical recombination lines ( orls ) are systematically higher than those derived from collisionally excited lines ( cels ; see liu 2001 , 2003 for recent reviews ) . in extreme cases ,
the discrepancies exceed a factor of 10 . given that cel abundances are sensitive to electron temperature and density , knowledge of temperature and density variations is an essential ingredient in understanding the abundance discrepancy problem ..
Please generate the next two sentences of the article | information on temperature and density variations can be obtained by comparing results derived from plasma diagnostics which behave differently as temperature and density vary .
traditionally , nebular electron temperatures and densities are derived from cel ratios . |
8,987 | Suppose that you have an abstract for a scientific paper: in the setting of quasi - static multiple - input multiple - output ( mimo ) channels , we consider the high signal - to - noise ratio ( snr ) asymptotic complexity required by the sphere decoding ( sd ) algorithm for decoding a large class of full rate linear space - time codes . with sd complexity having random fluctuations induced by the random channel , noise and codeword realizations ,
the introduced _ sd complexity exponent _ manages to concisely describe the computational reserves required by the sd algorithm to achieve arbitrarily close to optimal decoding performance .
bounds and exact expressions for the sd complexity exponent are obtained for the decoding of large families of codes with arbitrary performance characteristics . for the particular example of decoding
the recently introduced threaded cyclic division algebra ( cda ) based codes the only currently known explicit designs that are uniformly optimal with respect to the diversity multiplexing tradeoff ( dmt ) the sd complexity exponent is shown to take a particularly concise form as a non - monotonic function of the multiplexing gain . to date
, the sd complexity exponent also describes the minimum known complexity of any decoder that can provably achieve a gap to maximum likelihood ( ml ) performance which vanishes in the high snr limit .
diversity - multiplexing tradeoff , sphere decoding , complexity , space - time codes , large deviations . .
And you have already written the first three sentences of the full article: the past decade has seen the abundant use of the sphere decoding ( sd ) algorithm @xcite as a tool for facilitating near maximum likelihood ( ml ) decoding over the coherent delay - limited ( or quasi - static ) multiple - input multiple - output ( mimo ) channel .
the sd algorithm allows for efficient optimal or near optimal decoding of a large number of high rate space - time codes that map constituent constellation symbols linearly in space and time @xcite .
as the algorithm s computational cost depends on the fading channel , it is generally known that in implementing the sd algorithm , one can tradeoff computational complexity for error performance by selectively choosing when to decode and when not to ..
Please generate the next two sentences of the article | equivalently , in the presence of constraints on the computational reserves that may be allocated to decoding , the algorithm is faced with the prospect of encountering channel realizations that force it to violate its run - time constraints , thus having to declare decoding outages that inevitably reduce reliability .
this naturally raises the intriguing question of how large computational reserves are actually required for near ml performance . |
8,988 | Suppose that you have an abstract for a scientific paper: we construct an algebra of smooth functions over the tangent groupoid associated to any lie groupoid .
this algebra is a field of algebras over the closed interval @xmath0 $ ] which fiber at zero is the algebra of schwartz functions over the lie algebroid , whereas any fiber out of zero is the convolution algebra of the initial groupoid .
our motivation comes from index theory for lie groupoids .
in fact , our construction gives an intermediate algebra between the enveloping @xmath1-algebra and the convolution algebra of compactly supported functions of the tangent groupoid ; and it will allows us , in a further work , to define other analytic index morphisms as a sort of deformations . primary 58 - 06 , 19 - 06 ; secondary 58h15 , 19k56 .
lie groupoids , tangent groupoid , k - theory , index theory . .
And you have already written the first three sentences of the full article: the concept of groupoid is central in non commutative geometry .
groupoids generalize the concepts of spaces , groups and equivalence relations .
it is clear nowadays that groupoids are natural substitutes of singular spaces ..
Please generate the next two sentences of the article | many people have contributed to realizing this idea .
we can find for instance a groupoid - like treatment in dixmier s works on transformation groups , @xcite , or in brown - green - rieffel s work on orbit classification of relations , @xcite . |
8,989 | Suppose that you have an abstract for a scientific paper: we report heating rate measurements in a microfabricated gold - on - sapphire surface electrode ion trap with trapping height of approximately 240 @xmath0 m . using the doppler recooling method
, we characterize the trap heating rates over an extended region of the trap .
the noise spectral density of the trap falls in the range of noise spectra reported in ion traps at room temperature .
we find that during the first months of operation the heating rates increase by approximately one order of magnitude .
the increase in heating rates is largest in the ion loading region of the trap , providing a strong hint that surface contamination plays a major role for excessive heating rates .
we discuss data found in the literature and possible relation of anomalous heating to sources of noise and dissipation in other systems , namely impurity atoms adsorbed on metal surfaces and amorphous dielectrics . .
And you have already written the first three sentences of the full article: trapped ions provide a promising candidate to pursue quantum information processing .
successful implementations of basic quantum protocols as well as the creation of entangled states support this view @xcite . a promising route to scalability of ion - trap based quantum information processing was proposed in which segmented trap electrodes allow splitting , shuttling , and recombination of ion crystals @xcite .
to overcome the difficulties of assembling three - dimensional trap structures and simplify fabrication , several groups are developing planar ( surface ) ion traps where all electrodes lie within one plane and can be constructed using standard microfabrication methods @xcite . in particular , recently the nist group successfully transported ions through junctions in such planar traps @xcite . despite the recent progress.
Please generate the next two sentences of the article | , there are still a number of unresolved difficulties with planar traps . in the effort to develop this technology , one strives for miniaturization in order to easily achieve the high trap frequencies required for fast splitting of ion crystals @xcite , and to increase coupling rates in approaches where trapped ions are coupled to @xcite or via solid state elements @xcite .
thus , planar traps with ion - surface separations of less than 100 @xmath0 m are pursued . |
8,990 | Suppose that you have an abstract for a scientific paper: the study of magnetic correlations in dipolar - coupled nanomagnet systems with synchrotron scattering provides a means to uncover emergent phenomena and exotic phases , in particular in systems with thermally active magnetic moments . from the diffuse signal of soft resonant magnetic scattering
, we have measured magnetic correlations in a highly dynamic artificial kagome spin ice with sub-70 nm permalloy nanomagnets . on comparing experimental scattering patterns with monte carlo simulations based on a needle - dipole model ,
we conclude that kagome ice i phase correlations exist in our experimental system even in the presence of moment fluctuations , which is analogous to bulk spin ice and spin liquid behavior .
in addition , we describe the emergence of quasi - pinch points in the magnetic diffuse scattering in the kagome ice i phase .
these quasi - pinch points bear similarities to the fully developed pinch points with singularities of a magnetic coulomb phase , and continually evolve into the latter on lowering the temperature . the possibility to measure
magnetic diffuse scattering with soft x - rays opens the way to study magnetic correlations in a variety of nanomagnetic systems . .
And you have already written the first three sentences of the full article: artificial kagome spin ice is a well - known geometrically frustrated two - dimensional magnetic system.@xcite it consists of elongated ferromagnetic nanomagnets placed on the nodes of a kagome lattice , or equivalently on the bonds of the hexagonal lattice ( see fig . ) , and coupled via their dipolar magnetic fields .
most of the experimental studies on artificial spin ice have been performed on static systems@xcite or systems with slow magnetization dynamics@xcite using imaging techniques such as magnetic force microscopy ( mfm ) and x - ray photoemission electron microscopy ( peem ) . in recent years , however , thermally active artificial spin systems have gained a considerable interest@xcite and provided a successful route to reach the low - energy magnetic states of artificial spin ice.@xcite additionally , analysis of the thermal behavior of nanomagnetic systems is particularly important for understanding the limitations of future spintronic devices.@xcite however , as the dynamics of artificial spin systems gets faster , observations using traditional microscopy techniques become limited by their temporal resolution ( approximately 1 s for peem ) , so that the magnetic correlations of the systems with rapidly fluctuating moments can not be probed .
therefore , complementary techniques are needed to study magnetic correlations in systems with faster fluctuation timescales in order to gain information about the magnetic phases over a broad temperature range ..
Please generate the next two sentences of the article | this is particularly of interest for thermally - induced magnetization dynamics,@xcite order - disorder transitions@xcite and spin - wave excitations in magnonic crystals.@xcite here we show that soft x - ray resonant magnetic scattering ( sxrms ) is a highly sensitive momentum - resolved technique for studying magnetic correlations in mesoscopic systems with fast magnetization dynamics .
field - driven studies of athermal systems using this technique have already been reported , with measurements of the x - ray magnetic circular dichroism ( xmcd ) signals at the bragg peaks.@xcite such measurements can directly give information about the ordering in the sample or the net magnetic moment . |
8,991 | Suppose that you have an abstract for a scientific paper: we consider a nematic liquid crystal confined by two parallel flat substrates whose anchoring conditions vary periodically in one lateral direction . within the gaussian approximation
, we study the effective forces between the patterned substrates induced by the thermal fluctuations of the nematic director . the shear force oscillates as function of the lateral shift between the patterns on the lower and the upper substrates .
we compare the strength of this fluctuation - induced lateral force with the lateral van der waals force arising from chemically structured adsorbed monolayers .
the fluctuation - induced force in normal direction is either repulsive or attractive , depending on the model parameters .
[ present address : ] institute for studies in theoretical physics and mathematics ( ipm ) , school of physics , po box 19395 - 5531 , tehran , iran .
And you have already written the first three sentences of the full article: liquid crystals are characterized by large thermal fluctuations in their local orientational order arising from collective alignment of the long axis of their constituent molecules @xcite . due to such soft anisotropy
, liquid crystals tend to respond easily to external forces .
confining geometries such as thin films , on which most applications of liquid crystals are based , change the fluctuation spectrum ..
Please generate the next two sentences of the article | this can cause not only structural changes @xcite but also leads to fluctuation - induced effective forces between the substrates @xcite , also known as thermodynamic casimir effect . in correlated fluids such as liquid crystals this casimir force exhibits a universal power - law decay as a function of the separation between the substrates @xcite .
however , this behavior is modified in the presence of other characteristic scales in the system @xcite . in the case that the substrates are laterally modulated , discrete lateral modes of thermal fluctuations are also excited . under such conditions , in addition to the forces acting perpendicularly to the substrates , effective lateral forces arise @xcite with potentially interesting technological applications . |
8,992 | Suppose that you have an abstract for a scientific paper: we present new spectro - photometric nir observations of 16 post - starburst galaxies especially designed to test for the presence of strong carbon features of thermally pulsing agb ( tp - agb ) stars , as predicted by recent models of stellar population synthesis .
selection based on clear spectroscopic optical features indicating the strong predominance of stellar populations with ages between 0.5 and 1.5 gyr and redshift around 0.2 allows us to probe the spectral region that is most affected by the carbon features of tp - agb stars ( unaccessible from the ground for @xmath0 galaxies ) in the evolutionary phase when their impact on the ir luminosity is maximum . nevertheless , none of the observed galaxies display such features .
moreover the nir fluxes relative to optical are consistent with those predicted by the original bruzual & charlot ( 2003 ) models , where the impact of tp - agb stars is much lower than has been recently advocated . .
And you have already written the first three sentences of the full article: the modeling and interpretation of the spectral energy distribution ( sed ) of stellar populations via stellar population synthesis ( sps ) is a fundamental tool to understand galaxy properties and their evolution .
yet we are far from a complete comprehension and a reliable modeling of some stellar evolutionary phases which strongly affect the energy output of stellar populations . among them , the so - called thermally pulsing - asymptotic giant branch ( tp - agb for short ) phase has been the focus of debate among modelists for several years ( e.g. ( * ? ? ?
* maraston 2005 ) ; ( * ? ? ?.
Please generate the next two sentences of the article | * bruzual 2007 ) ; ( * ? ? ?
* marigo 2008 ) ) . |
8,993 | Suppose that you have an abstract for a scientific paper: polyhomeostatic adaption occurs when evolving systems try to achieve a target distribution function for certain dynamical parameters , a generalization of the notion of homeostasis . here
we consider a single rate encoding leaky integrator neuron model driven by white noise , adapting slowly its internal parameters , the threshold and the gain , in order to achieve a given target distribution for its time - average firing rate .
for the case of sparse encoding , when the target firing - rated distribution is bimodal , we observe the occurrence of spontaneous quasi - periodic adaptive oscillations resulting from fast transition between two quasi - stationary attractors .
we interpret this behavior as self - organized stochastic tipping , with noise driving the escape from the quasi - stationary attractors . .
And you have already written the first three sentences of the full article: self - regulation plays an important role in biological and technical systems .
homeostatically regulated steady states are a precondition to life , examples being the concentration of blood glucose controlled by insulin @xcite and glucagon , the ph value of blood @xcite and the body temperature @xcite , which are all autoregulated in order to maintain stable conditions .
further examples are the concentration of ions , proteins and transmitters in the brain , their respective levels are all self regulated @xcite . furthermore , homeostasis is implemented and can be found in technical systems , for example in microrobotic swarms @xcite ..
Please generate the next two sentences of the article | adaption typically introduces a slow time scale into the dynamical system @xcite , a process also denoted meta learning , a central notion in the context of neuromodulation @xcite and emotional control @xcite .
the resulting dynamical system then has both fast and slow variables and critical transitions in the form of tipping processes may occur @xcite . |
8,994 | Suppose that you have an abstract for a scientific paper: a search for axioelectric absorption of 5.5 mev solar axions produced in the @xmath0 reaction has been performed with a bgo detectors .
a model - independent limit on the product of axion - nucleon @xmath1 and axion - electron @xmath2 coupling constants has been obtained : @xmath3 for 90% c.l .. .
And you have already written the first three sentences of the full article: there are new possibilities for strong cp problem solution , which allow the existence of axions with a large mass ( 1 mev ) , while their interaction with ordinary particles remain at the level of the invisible axions .
the models rely on the hypothesis of mirror particles @xcite and susy at the tev scale @xcite .
the existence of these heavy axions is not forbidden by the laboratory experiments or astrophysical data ..
Please generate the next two sentences of the article | this article describes the experimental search for 5.5 mev solar axions , which can be produced by @xmath4 reaction .
axion flux should be proportional to the @xmath5-neutrino flux , which has been estimated with high accuracy @xcite . |
8,995 | Suppose that you have an abstract for a scientific paper: recent data on the nuclear modification factor @xmath0 of jet fragments in @xmath1 atev pb+pb collisions at the large hadron collider ( lhc ) indicate that the jet - medium coupling in a quark - gluon plasma ( qgp ) is reduced at lhc energies and not compatible with the coupling deduced from data at the relativistic hadron collider ( rhic ) .
we estimate the reduction factor from a combined fit to the available data on @xmath2 and the elliptic flow @xmath3 at @xmath4 atev over a transverse momentum range @xmath5 gev and a broad impact parameter , @xmath6 , range .
we use a simple analytic `` polytrope '' model ( @xmath7 ) to investigate the dynamical jet - energy loss model dependence . varying @xmath8 interpolates between weakly - coupled and strongly - coupled models of jet - energy dependence while @xmath9 covers a wide range of possible jet - path dependencies from elastic and radiative to holographic string mechanisms .
our fit to lhc data indicates an approximate 40% reduction of the coupling @xmath10 from rhic to lhc and excludes energy - loss models characterized by a jet - energy exponent with @xmath11 . in particular , the rapid rise of @xmath0 with @xmath12 gev combined with the slow variation of the asymptotic @xmath13 at the lhc rules out popular exponential geometric optics models ( @xmath14 ) .
the lhc data are compatible with @xmath15 pqcd - like energy - loss models where the jet - medium coupling is reduced by approximately 10% between rhic and lhc . .
And you have already written the first three sentences of the full article: first data from the large hadron collider ( lhc ) on the nuclear - size dependence of jet - medium interactions in pb+pb collisions at @xmath16 atev @xcite showed that the jet - medium coupling at the lhc is weaker than expected @xcite from fixed coupling extrapolations from @xmath17 atev data at the relativistic heavy ion collider ( rhic ) @xcite . from the factor of @xmath18 increase of global multiplicity per unit rapidity , @xmath19 in central pb+pb reactions at the lhc
relative to rhic , substantially more suppression of high-@xmath20 pions was predicted than observed . in this paper
we estimate the reduction of the jet - medium coupling implied by the new data and test the consistency for a wide variety of jet - energy loss models ..
Please generate the next two sentences of the article | an open question from studies of the nuclear modification factor of jets at rhic is whether jet - medium interactions in dense deconfined quark - gluon plasma ( qgp)-matter can be better described in terms of weakly - coupled perturbative qcd ( pqcd ) tomography or novel strongly - coupled gravity - dual anti - de - sitter / conformal field theory ( ads / cft ) string - model holography @xcite .
the first data from lhc provide stringent new tests of jet - medium interaction models for a higher qgp - density range and for an order of magnitude higher transverse momentum range . |
8,996 | Suppose that you have an abstract for a scientific paper: we report on a time regularity result for stochastic evolutionary pdes with monotone coefficients .
if the diffusion coefficient is bounded in time without additional space regularity we obtain a fractional sobolev type time regularity of order up to @xmath0 for a certain functional @xmath1 of the solution .
namely , @xmath2 in the case of the heat equation and @xmath3 for the @xmath4-laplacian .
the motivation is twofold . on the one hand
, it turns out that this is the natural time regularity result that allows to establish the optimal rates of convergence for numerical schemes based on a time discretization . on the other hand , in the linear case
, i.e. where the solution is given by a stochastic convolution , our result complements the known stochastic maximal space - time regularity results for the borderline case not covered by other methods . .
And you have already written the first three sentences of the full article: let @xmath5 be separable hilbert spaces and let @xmath6 be a banach space such that @xmath7 is a gelfand triple with continuous and dense embeddings .
we are interested in stochastic evolution equations of the form @xmath8 where @xmath9 is a @xmath10-valued cylindrical wiener process on a probability space @xmath11 with a normal filtration @xmath12 and the maps @xmath13\times v\to v',\qquad b:\omega\times[0,t]\times h\to l_2(u;h)\ ] ] are @xmath12-progressively measurable and satisfy 1 .
[ eq : mu2 ] monotonicity : there exists @xmath14 such that for all @xmath15 , @xmath16 $ ] @xmath17 2 ..
Please generate the next two sentences of the article | [ eq : mu0 ] hemicontinuity : for all @xmath18 , @xmath19 and @xmath16,$ ] the mapping @xmath20 is continuous .
[ eq : mu ] coercivity : there exist @xmath21 , @xmath22 , @xmath23 such that for all @xmath24 , @xmath16 $ ] @xmath25 4 . |
8,997 | Suppose that you have an abstract for a scientific paper: by studying the stellar population properties along the radius in 15 nearby s0 galaxies , i have found that the outer stellar disks are mostly old , with the ssp - equivalent ages of 815 gyr , being often older than the bulges .
this fact puts into doubt a currently accepted paradigm that s0 galaxies have formed at @xmath0 by quenching star formation in spiral galaxies . .
And you have already written the first three sentences of the full article: lenticular galaxies have been introduced by edwin ( * ? ? ? * hubble ( 1936 ) ) as an intermediate type between ellipticals and spirals : they have large - scale stellar disks as spirals but lack blue spiral arms and hii - regions , and they look smooth and red as ellipticals . now lenticulars are thought to be ( trans-)formed from spirals by removing gas and quenching star formation in their disks ; also dynamical heating is required to make the s0 disks stable against spiral wave perturbations .
there are some evidences that this transformation might take place at the redshift of @xmath1 , within dense environments , groups or clusters , where and when suddenly the dominance of blue ( spiral ? ) galaxies is replaced by s0 dominance ( e.g. , ( * ? ? ?
* fasano et al ..
Please generate the next two sentences of the article | 2000 ) , ( * ? ? ?
* wilman et al . 2009 ) ) . |
8,998 | Suppose that you have an abstract for a scientific paper: we evaluate the exposure during nadir observations with jem - euso , the extreme universe space observatory , on - board the japanese experiment module of the international space station . designed as a mission to explore the extreme energy universe from space
, jem - euso will monitor the earth s nighttime atmosphere to record the ultraviolet light from tracks generated by extensive air showers initiated by ultra - high energy cosmic rays . in the present work ,
we discuss the particularities of space - based observation and we compute the annual exposure in nadir observation .
the results are based on studies of the expected trigger aperture and observational duty cycle , as well as , on the investigations of the effects of clouds and different types of background light .
we show that the annual exposure is about one order of magnitude higher than those of the presently operating ground - based observatories . .
And you have already written the first three sentences of the full article: the origin and nature of ultra - high energy cosmic rays ( uhecrs ) remains unsolved in contemporary astroparticle physics .
possible indications of sources or excesses in the arrival direction distribution of uhecrs have been claimed by ground - based experiments , though not fully confirmed @xcite . in order to be identified from earth , extremely powerful sources capable of accelerating cosmic rays up to ultra - high energies must be within a limited range of distances set by the greisen - zatseptin - kuzmin ( gzk ) effect @xcite .
since the distribution of matter within the gzk range is inhomogeneous and anisotropic , one would expect uhecr arrival directions to exhibit a corresponding anisotropy . to identify the sources of uhecrs , measurements of the energy spectrum and arrival directions with high statistics are essential ..
Please generate the next two sentences of the article | this is rather challenging because of the extremely low flux of a few per km@xmath0 per century at extreme energies such as @xmath1 ev .
the observational exposure is , therefore , a critical factor . |
8,999 | Suppose that you have an abstract for a scientific paper: this paper presents the `` game theory explorer '' software tool to create and analyze games as models of strategic interaction .
a game in extensive or strategic form is created and nicely displayed with a graphical user interface in a web browser .
state - of - the - art algorithms then compute all nash equilibria of the game after a mouseclick . in tutorial fashion , we present how the program is used , and the ideas behind its main algorithms .
we report on experiences with the architecture of the software and its development as an open - source project .
* keywords * game theory , nash equilibrium , scientific software .
And you have already written the first three sentences of the full article: game theory provides mathematical concepts and tools for modeling and analyzing interactive scenarios . in _
noncooperative _ game theory , the possible actions of the players are represented explicitly , together with payoffs that the players want to maximize for themselves .
basic models are the _ extensive _ form represented by a game tree with possible imperfect information represented by information sets , and the _ strategic _ ( or `` normal '' ) form that lists the players strategies , which they choose independently , together with a table of the players payoffs for each strategy profile ..
Please generate the next two sentences of the article | the central concept for noncooperative games is the _ nash equilibrium _ which prescribes a strategy for each player that is optimal when the other players keep their prescribed strategies fixed .
every finite game has an equilibrium when players are allowed to _ mix _ ( randomize ) their actions ( nash , 1951 ) . |
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