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Suppose that you have an abstract for a scientific paper: we study the competition and the evolution of nodes embedded in euclidean restricted spaces . the population evolves by a branching process in which new nodes are generated when up to two new nodes are attached to the previous ones at each time unit . the competition in the population is introduced by considering the effect of overcrowding of nodes in the embedding space . the branching process is suppressed if the newborn node is closer than a distance @xmath0 of the previous nodes . this rule may be relevant to describe a competition for resources , limiting the density of individuals and therefore the total population . this results in an exponential growth in the initial period , and , after some crossover time , approaching some limiting value . our results show that the competition among the nodes associated with geometric restrictions can even , for certain conditions , lead the entire population to extinction . . And you have already written the first three sentences of the full article: a growing tree - like network can model different processes such as a technological or biological systems represented by a set of nodes , where each element in the network can create new elements . innovation and discovery @xcite , artistic expression and culture @xcite , language structures @xcite and the evolution of life @xcite can naturally be represented by a branching process in a tree @xcite describing a wide range of real - life processes and phenomena @xcite . the general branching process is defined mathematicaly as a set of objects ( nodes ) that do not interact and , at each time step , each object can give rise to new objects .. Please generate the next two sentences of the article

in contrast , interacting branching processes are much more interesting and difficult for analysis @xcite . a generalized tree with one ( or more ) ancestor(s ) have been used to depict evolutionary relationships between interacting nodes such as genes , species , cultures . besides the interaction among nodes

Suppose that you have an abstract for a scientific paper: a large position angle misalignment between the stellar bar and the distribution of dust in the late - type barred spiral was discovered , using mid - infrared images from the _ spitzer space telescope _ and optical images from the sloan digital sky survey ( sdss ) . the angle between the bar and dust patterns was measured to be 25@xmath0@xmath12@xmath0 , larger than most of the misalignments found previously in barred systems based on h@xmath2 or h i / co observations . the stellar bar is bright at optical and 3.6@xmath3 m , while the dust pattern is more prominent in the 8@xmath3 m band but also shows up in the sdss _ u _ and _ g_-band images , suggesting a rich interstellar medium environment harboring ongoing star formation . this angular misalignment is unlikely to have been caused by spontaneous bar formation . we suggest that the stellar bar and the dust pattern may have different formation histories , and that the large misalignment was triggered by a tidal interaction with a small companion . a statistical analysis of a large sample of nearby galaxies with archival _ spitzer _ data indicates that bar structure such as that seen in is quite rare in the local universe . galaxies : individual ( ) , galaxies : spiral , galaxies : structure , infrared : galaxies + 98.62.hr . And you have already written the first three sentences of the full article: bar structure as a major non - axisymmetric feature on all scales is important in studying the morphology , mass and light distributions ( e.g. , freeman 1996 ; elmegreen & elmegreen 1985 ; elmegreen 1996 ; elmegreen et al . 1996 ; eskridge et al . 2000 ; menndez - delmestre et al . 2007 ) , star formation ( e.g. , zurita et al . 2004 ; knapen 2005 ; ondrechen & van der hulst 1983 ; regan et al .. Please generate the next two sentences of the article

1996 ; sheth et al . 2000 ) , gas dynamics ( e.g. , kormendy 1983 ; bettoni & galletta 1988 ; sancisi et al .

Suppose that you have an abstract for a scientific paper: the influence of the collimating conditions of the incident beam on diffraction patterns produced by grazing scattering of fast atoms off crystal surfaces is studied within a semi - quantum approach , named surface initial value representation ( sivr ) approximation . in this approach we incorporate a realistic description of the incident particle in terms of the collimating parameters , which determine the surface area that is coherently illuminated . the model is applied to he atoms colliding with a lif(001 ) surface after passing through a rectangular aperture . as it was experimentally observed @xcite , sivr spectra as a function of the azimuthal angle are very sensitive to the width of the collimating slit . we also found that the length of the collimating aperture affects polar angle distributions , introducing additional interference structures for the longer collimating slits . . And you have already written the first three sentences of the full article: diffraction patterns produced by grazing scattering of swift atoms and molecules ( with energies in the kev range ) on surfaces are nowadays becoming a powerful surface analysis tool , which is giving rise to a technique known as grazing - incidence fast atom diffraction ( gifad or fad ) winter11,zugarramurdi15 . in recent years the fad method was successfully applied to very different kinds of materials , ranging from insulators schuller07,rousseau07,schuller12 to semiconductors khemliche09,debiossac14 and metals @xcite , as well as structured films @xcite and molecules seifertprl13 adsorbed on surfaces . however , in spite of the extensive experimental and theoretical work devoted to the research of fad since its first experimental observation @xcite , the complete understanding of the underlying quantum processes is far from being achieved . in particular , the study of the mechanisms that contribute to the coherence or decoherence of the scattered particles is still in its infancy . the observation of quantum interference effects for fast atoms impinging on crystal surfaces strongly relies on the preservation of quantum coherence @xcite and in this regard , the coherence conditions of the incident beam play an important role . motivated by ref .. Please generate the next two sentences of the article

@xcite , in this article we investigate the influence of the collimation of the incident beam on fad patterns making use of a recently developed approach , named surface - initial value representation ( sivr ) approximation @xcite . with this goal we explicitly take into account the experimental collimating conditions to determine the surface region that is _ coherently _ illuminated by the particle beam , using this information to build the initial wave packet that describes the unperturbed state of the incident particle within the sivr method .

Suppose that you have an abstract for a scientific paper: we present a proof of a conjecture about the relationship between baxter permutations and pairs of alternating sign matrices that are produced from domino tilings of aztec diamonds . it is shown that if and only if a tiling corresponds to a pair of asms that are both permutation matrices , the larger permutation matrix corresponds to a baxter permutation . there has been a thriving literature on both pattern - avoiding permutations of various kinds @xcite @xcite and tilings of regions using dominos or rhombuses as tiles @xcite @xcite . however , there have not as of yet been many links between these two areas of enumerative combinatorics . this paper gives one such link . . And you have already written the first three sentences of the full article: figure [ toad ] shows two of the 64 different ways of tiling an order three aztec diamond with dominoes . aztec diamonds are defined in `` alternating - sign matrices and domino tilings , '' by elkies , kuperberg , larsen , and propp @xcite . each tiling will be referred to as a toad , a tiling of an aztec diamond . in all of the illustrations. Please generate the next two sentences of the article

, we have rotated the aztec diamonds and drawn spurs on each corner to simplify later calculations . an alternating sign matrix ( asm ) is a square matrix whose entries are @xmath0 , @xmath1 , or @xmath2 , such that the entries of each row or column must add up to @xmath1 , and all nonzero entries must alternate in sign .

Suppose that you have an abstract for a scientific paper: one of the striking examples of episodic activity in active galactic nuclei are the double - double radio galaxies ( ddrgs ) with two pairs of oppositely - directed radio lobes from two different cycles of activity . we illustrate , using the ddrg j1453 + 3308 as an example , that observations over a wide range of frequencies using both the gmrt and the vla can be used to determine the spectra of the inner and outer lobes , estimate their spectral ages , estimate the time scales of episodic activity , and examine any difference in the injection spectra in the two cycles of activity . low - frequency gmrt observations also suggest that ddrgs and triple - double radio galaxies are rather rare . . And you have already written the first three sentences of the full article: for active galactic nuclei ( agn ) , an important and interesting issue is the duration of their active phase and the time scales for recurrence of such periods of activity . it is believed widely that the central activity is related to the feeding of a supermassive black hole in the centre of the galaxy . one of the more striking examples of episodic activity is when a new pair of radio lobes is seen closer to the nucleus in a radio loud agn before the older and more distant radio lobes have faded .. Please generate the next two sentences of the article

such sources have been named double - double radio galaxies ( ddrgs ; schoenmakers et al . a ddrg consists of a pair of double radio sources with a common core , where the two lobes of the inner double have an edge - brightened radio morphology . in such sources

Suppose that you have an abstract for a scientific paper: a deterministic mutation selection model in the sequence space approach is investigated . genotypes are identified with two - letter sequences . mutation is modelled as a markov process , fitness functions are of hopfield type , where the fitness of a sequence is determined by the hamming distances to a number of predefined patterns . using a maximum principle for the population mean fitness in equilibrium , the error threshold phenomenon is studied for quadratic hopfield - type fitness functions with small numbers of patterns . different from previous investigations of the hopfield model , the system shows error threshold behaviour not for all fitness functions , but only for certain parameter values . mutation selection model , hopfield model , error threshold , maximum principle . And you have already written the first three sentences of the full article: population genetics is concerned with the investigation of the genetic structure of populations , which is influenced by evolutionary factors such as mutation , selection , recombination , migration and genetic drift . for excellent reviews of the theoretical aspects of this field , see @xcite . in this paper , the antagonistic interplay of mutation and selection shall be investigated , with mutation generating the genetic variation upon which selection can act .. Please generate the next two sentences of the article

pure mutation selection models exclude genetic drift and are therefore deterministic models , and accurate only in the limit of an infinite population size ( for a review , see * ? ? ?

Suppose that you have an abstract for a scientific paper: rigged configurations are combinatorial objects originating from the bethe ansatz , that label highest weight crystal elements . in this paper a new _ unrestricted _ set of rigged configurations is introduced for types @xmath0 by constructing a crystal structure on the set of rigged configurations . in type @xmath1 an explicit characterization of unrestricted rigged configurations is provided which leads to a new fermionic formula for unrestricted kostka polynomials or @xmath2-supernomial coefficients . the affine crystal structure for type @xmath1 is obtained as well . . And you have already written the first three sentences of the full article: there are ( at least ) two main approaches to solvable lattice models and their associated quantum spin chains : the bethe ansatz @xcite and the corner transfer matrix method @xcite . in his 1931 paper @xcite , bethe solved the heisenberg spin chain based on the string hypothesis which asserts that the eigenvalues of the hamiltonian form certain strings in the complex plane as the size of the system tends to infinity . the bethe ansatz has been applied to many models to prove completeness of the bethe vectors .. Please generate the next two sentences of the article

the eigenvalues and eigenvectors of the hamiltonian are indexed by rigged configurations . however , numerical studies indicate that the string hypothesis is not always true @xcite .

Suppose that you have an abstract for a scientific paper: elliptical galaxies and their groups having the largest @xmath0 lie close to the locus @xmath1 expected for closed systems having baryon fractions equal to the cosmic mean value , @xmath2 . the estimated baryon fractions for several of these galaxies / groups are also close to @xmath3 when the gas density is extrapolated to the virial radius . evidently they are the least massive baryonically closed systems . gas retention in these groups implies that non - gravitational heating can not exceed about 1 kev per particle , consistent with the heating required to produce the deviation of groups from the @xmath4 correlation for more massive clusters . isolated galaxies / groups with x - ray luminosities significantly lower than baryonically closed groups may have undermassive dark halos , overactive central agns , or higher star formation efficiencies . the virial mass and hot gas temperatures of nearly or completely closed groups correlate with the group x - ray luminosities and the optical luminosities of the group - centered elliptical galaxy , i.e. @xmath5 , an expected consequence of their merging history . the ratio of halo mass to the mass of the central galaxy for x - ray luminous galaxy / groups is @xmath6 . . And you have already written the first three sentences of the full article: massive elliptical galaxies with similar optical luminosities have hot gas x - ray luminosities that range over two orders of magnitude . the origin of this scatter , shown in figure 1 , has received much attention but a full understanding remains elusive . there is evidence that gas loss by ram pressure ( and tidal ) stripping has reduced @xmath0 in elliptical galaxies or groups orbiting within rich clusters of galaxies ( biller et al .. Please generate the next two sentences of the article

2004 ; machacek et al . 2005 ; sun et al . 2005 ) .

Suppose that you have an abstract for a scientific paper: the sky distribution of cosmic rays with energies above the ` gzk cutoff ' holds important clues to their origin . the agasa data , although consistent with isotropy overall , shows evidence for small - angle clustering , and it has been argued that such clusters are aligned with bl lacertae objects , implicating these as the sources . it has also been suggested that such clusters can arise if the cosmic rays come from the decays of very massive relic particles in the galactic halo , due to the expected clumping of cold dark matter . we examine these claims and show that both are , in fact , unjustified . . And you have already written the first three sentences of the full article: the mystery of the ultra - high energy cosmic rays ( uhecrs ) with energies exceeding @xmath0 ev the greisen - zatsepin - kuzmin ( gzk ) ` cutoff ' @xcite continues to deepen . this energy sets the threshold for photomeson production on the cosmic microwave background so the observation of such uhecrs ( assumed to be protons or heavier nuclei ) would indicate that the sources are relatively nearby , within the local supercluster of galaxies @xcite . recent observations by the hires air fluorescence detector @xcite are however inconsistent with previously published data from the akeno giant air shower array ( agasa ) which ruled out such a cutoff with a significance @xmath1 @xcite .. Please generate the next two sentences of the article

hires has reported only 1 event above @xmath2 ev , whereas about 20 would have been expected on the basis of the agasa spectrum . the two spectra can be made to agree _ below _ this energy , if the energies of the agasa events are systematically lowered by 20% ( within the quoted uncertainty ) , however 5 of them still remain above this energy @xcite .

Suppose that you have an abstract for a scientific paper: we investigate the stellar disk properties of a sample of 19 nearby spiral galaxies with low inclination and late hubble type ( scd or later ) . we combine our high - resolution _ hubble space telescope _ i - band observations with existing ground - based optical images to obtain surface brightness profiles that cover a high dynamic range of galactic radius . most of these galaxies contain a nuclear star cluster , as discussed in a separate paper . the main goal of the present work is to constrain the properties of stellar bulges at these extremely late hubble types . we find that the surface brightness profiles of the latest - type spirals are complex , with a wide range in shapes . we have sorted our sample in a sequence , starting with `` pure '' disk galaxies ( approximately 30% of the sample ) . these galaxies have exponential stellar disks that extend inwards to within a few tens of pc from the nucleus , where the light from the nuclear cluster starts to dominate . they appear to be truly bulge - less systems . progressing along the sequence , the galaxies show increasingly prominent deviations from a simple exponential disk model on kpc scales . traditionally , such deviations have prompted `` bulge - disk '' decompositions . indeed , the surface brightness profiles of these galaxies are generally well fit by adding a second ( exponential ) bulge component . however , we find that most surface brightness profiles can be fit equally well ( or better ) with a single srsic - type @xmath0 profile over the entire radial range of the galaxy , without requiring a separate `` bulge '' component . we warn in a general sense against identification of bulges solely on the basis of single - band surface brightness profiles . despite the narrow range of hubble types in our sample , the surface brightness profiles are far from uniform . the differences between the various galaxies appear unrelated to their hubble - types , thus questioning the usefulness of the hubble - sequence for the.... And you have already written the first three sentences of the full article: the question whether the morphology of galaxies is imprinted by the initial conditions of their formation or rather determined by secular evolution remains a subject of intense debate . the existence of the hubble sequence has for many years provided important constraints on this issue . in very simple terms the hubble sequence tells us that galaxies are made up of two components : a bulge and a disk .. Please generate the next two sentences of the article

the canonical view of these components has long been that bulges have @xmath1 surface brightness profiles @xcite while disks have exponential surface brightness profiles . as one goes from early - type to late - type galaxies one goes from galaxies that are bulge - dominated to galaxies that are disk - dominated .

Suppose that you have an abstract for a scientific paper: we consider a graphical approach to index coding . while cycles have been shown to provide coding gain , only disjoint cycles and cliques ( a specific type of overlapping cycles ) have been exploited in existing literature . in this paper , we define a more general form of overlapping cycles , called the interlinked - cycle ( @xmath0 ) structure , that generalizes cycles and cliques . we propose a scheme , called the interlinked - cycle - cover ( @xmath1 ) scheme , that leverages @xmath0 structures in digraphs to construct scalar linear index codes . we characterize a class of infinitely many digraphs where our proposed scheme is optimal over all linear and non - linear index codes . consequently , for this class of digraphs , we indirectly prove that scalar linear index codes are optimal . furthermore , we show that the @xmath1 scheme can outperform all existing graph - based schemes ( including partial - clique - cover and fractional - local - chromatic number schemes ) , and a random - coding scheme ( namely , composite coding ) for certain graphs . shell : bare demo of ieeetran.cls for journals index coding problem , unicast , linear index codes , interlinked - cycle cover , optimal broadcast rate . . And you have already written the first three sentences of the full article: index coding ( introduced by birk and kol @xcite in 1998 ) , a sender broadcasts messages through a noiseless shared channel to multiple receivers , each knowing some messages a priori , which are known as side information . side information occurs frequently in many communication networks , e.g. , in a web browsers cache . knowing the side information of the receivers , the sender can send coded symbols , known as an index code , in such a way that all of the receivers can decode their requested messages using their side information and the received coded symbols .. Please generate the next two sentences of the article

the aim is to find the shortest ( optimal ) index code . how to optimally design an index code for an arbitrary index - coding instance is an open problem to date . in the literature

Suppose that you have an abstract for a scientific paper: all possible symmetry - determined nonlinear normal modes ( also called by simple periodic orbits , one - mode solutions etc . ) in both hard and soft fermi - pasta - ulam-@xmath0 chains are discussed . a general method for studying their stability in the thermodynamic limit , as well as its application for each of the above nonlinear normal modes are presented . . And you have already written the first three sentences of the full article: this paper is devoted to studying the stability of dynamical objects which are called by very different terms such as one - mode solutions ( omss ) @xcite , simple periodic orbits ( spos ) @xcite , low - dimensional solutions @xcite , one - dimensional bushes @xcite etc . below we refer to them as _ nonlinear normal modes _ ( nnms ) . let us comment on this terminology .. Please generate the next two sentences of the article

the concept of similar nonlinear normal modes was developed by rosenberg many years ago @xcite . each nnm represents a periodic vibrational regime in the conservative @xmath1-particle mechanical system for which the displacement @xmath2 of every particle is proportional to the displacement of an arbitrary chosen particle , say , the first particle [ @xmath3 at any instant @xmath4 : @xmath5 where @xmath6 are constant coefficients .

Suppose that you have an abstract for a scientific paper: we show that respecting the underlying lorentz structure in the parton model has very strong consequences . failure to insist on the correct lorentz covariance is responsible for the existence of contradictory results in the literature for the polarized structure function @xmath0 , whereas with the correct imposition we are able to derive the wandzura - wilczek relation for @xmath0 and the target - mass corrections for polarized deep inelastic scattering _ without _ recourse to the operator product expansion . we comment briefly on the problem of threshold behaviour in the presence of target - mass corrections . careful attention to the lorentz structure has also profound implications for the structure of the transverse momentum dependent parton densities often used in parton model treatments of hadron production , allowing the @xmath1 dependence to be _ derived explicitly_. it also leads to stronger positivity and soffer - type bounds than usually utilized for the collinear densities . . And you have already written the first three sentences of the full article: in this paper we shall show that imposition of the correct lorentz structure in the parton model allows us to relate two issues which , _ a priori _ , do not seem to be connected with each other : the derivation of a consistent expression for the polarized deep inelastic scattering ( dis ) structure function @xmath0 in the parton model , and the derivation of the higher twist target - mass corrections i.e. corrections of the form @xmath2 , where @xmath3 is the nucleon mass , to @xmath4 and @xmath5 . as will be discussed below , the target - mass corrections have previously been derived in a very complicated way from the operator product expansion ( ope ) , and the derivation of the wandzura - wilczek ( ww ) expression for @xmath0 has involved a questionable analytic continuation in the ope moments @xcite . it is thus particularly interesting that these results can be derived in a field theoretic context without use of the ope .. Please generate the next two sentences of the article

target - mass corrections for _ unpolarized _ dis were first derived by nachtmann @xcite employing a very elegant mathematical approach in which the power series expansion used in the ope was replaced by an expansion into a series of hyperspherical functions ( representation functions of the homogeneous lorentz group ) . later , also within the context of the ope , georgi and politzer @xcite re - derived nachtmann s results using what they called an alternative analysis for simple - minded souls like ourselves " i.e. based on a straightforward power series expansion but , in fact , requiring a very clever handling of the combinatoric aspects of the problem .

Suppose that you have an abstract for a scientific paper: we construct the explicit one loop functional of chiral perturbation theory for two light flavours , including virtual photons . we stick to contributions where 1 or 2 mesons and at most one photon are running in the loops . with the explicit functional at hand , the evaluation of the relevant green functions boils down to performing traces over the flavour matrices . for illustration , we work out the @xmath0 scattering amplitude at threshold at order @xmath1 . butp-02/13 * explicit generating functional for pions and virtual photons * j. schweizer + institute for theoretical physics , + university of bern , + sidlerstr . 5 , ch3012 bern , switzerland + e - mail : schweizer@itp.unibe.ch march 31 , 2003 . And you have already written the first three sentences of the full article: the low energy structure of qcd may be investigated in the context of chiral perturbation theory @xcite . in refs . @xcite gasser and leutwyler constructed the generating functional of @xmath2 for @xmath3 to order @xmath4 . an explicit representation of this functional , including graphs with up to two propagators and at most four external pion fields , was also given .. Please generate the next two sentences of the article

for the first two flavours @xmath5 and @xmath6 , this construction was extended recently to include graphs with three propagators @xcite . in the case of qcd including electromagnetic interactions , the initial theory depends on the strong coupling constant @xmath7 , the fine structure constant @xmath8 and the light quark masses . the corresponding effective theory was formulated in refs . .

Suppose that you have an abstract for a scientific paper: when a source star is microlensed by one stellar component of a widely separated binary stellar components , after finishing the lensing event , the event induced by the other binary star can be additionally detected . in this paper , we investigate whether the close / wide degeneracies in binary lensing events can be resolved by detecting the additional centroid shift of the source images induced by the secondary binary star in wide binary lensing events . from this investigation , we find that if the source star passes close to the einstein ring of the secondary companion , the degeneracy can be easily resolved by using future astrometric follow - up observations with high astrometric precision . we determine the probability of detecting the additional centroid shift in binary lensing events with high magnification . from this , we find that the degeneracy of binary lensing events with a separation of @xmath0 au can be resolved with a significant efficiency . we also estimate the waiting time for the detection of the additional centroid shift in wide binary lensing events . we find that for typical galactic lensing events with a separation of @xmath0 au , the additional centroid shift can be detected within @xmath1 days , and thus the degeneracy of those events can be sufficiently broken within a year . . And you have already written the first three sentences of the full article: observations are currently being undertaken for the detection of microlensing events , with survey observations being carried out by the ogle @xcite and moa @xcite groups , and with follow - up observations being performed by the planet @xcite and microfun @xcite groups . the follow - up observations are focusing on high magnification events toward the galactic bulge , so that they are efficient for detecting events with the characteristic features of binary lens systems , such as the caustic - crossing appearing in high magnification events . moreover , if future space missions such as _ microlensing planet finder _ ( _ mpf _. Please generate the next two sentences of the article

@xcite ) with high photometric precision and monitoring cadence are carried out , the efficiency will significantly increase , and thus many more binary lensing events with the characteristic features will be found . detection of binary microlensing events is important for providing various information about the lensing parameters .

Suppose that you have an abstract for a scientific paper: the ginzburg - landau equations are solved for ideally periodic vortex lattices in superconducting films of arbitrary thickness in a perpendicular magnetic field . the order parameter , current density , magnetic moment , and the 3-dimensional magnetic field inside and outside the film are obtained in the entire ranges of the applied magnetic field , ginzburg landau parameter @xmath0 , and film thickness . the superconducting order parameter varies very little near the surface ( @xmath1 ) and the energy of the film surface is small . the shear modulus @xmath2 of the triangular vortex lattice in thin films coincides with the bulk @xmath2 taken at large @xmath0 . in thin type - i superconductor films with @xmath3 , @xmath2 can be positive at low fields and negative at high fields . the magnetization of thin films at small applied fields is enhanced beyond its bulk value @xmath4 due to the energy of the magnetic stray field . . And you have already written the first three sentences of the full article: since abrikosov s @xcite prediction of the flux - line lattice in type - ii superconductors from ginzburg - landau ( gl ) theory , most theoretical work on this vortex lattice in bulk and thin film superconductors considered the situation when the applied magnetic field and the average induction @xmath5 are close to the upper critical field @xmath6 , since analytical solutions may be obtained for this particular case . in the opposite limit of low induction @xmath7 , the properties of an isolated vortex and the interaction between vortices are obtained to good approximation from the london theory when the gl parameter @xmath0 is not too small , @xmath8 . @xcite the problem of an isolated vortex in thin films was solved analytically within london theory by pearl @xcite ; the interaction energy of such pearl vortices ( or pancake vortices @xcite ) is easily calculated by noting that within london theory the currents and magnetic fields of the vortices superimpose linearly and that the force on a vortex equals the thickness - integrated super - current density at the vortex core times the quantum of flux @xmath9 . in thin films with thickness @xmath10 smaller than the london magnetic penetration depth @xmath11 the range of the vortex vortex interaction is increased to the effective penetration depth @xmath12 since the interaction now occurs mainly via the magnetic stray field outside the film .. Please generate the next two sentences of the article

@xcite vortices in superconducting films of finite thickness ( @xmath13 and @xmath14 ) and in the superconducting half space ( @xmath15 ) were calculated from gl theory @xcite and london theory . @xcite at larger reduced induction @xmath16 when the london theory does not apply , the properties of the gl vortex lattice have to be computed numerically .

Suppose that you have an abstract for a scientific paper: a monte carlo - maximum entropy calculation of the optical conductivity of the infinite - dimensional hubbard model is presented . we show that the optical conductivity displays the anomalies found in the cuprate superconductors , including a drude width which grows linearly with temperature , a drude weight which grows linearly with doping , and a temperature and doping - dependent mid - ir peak . these anomalies arise as a consequence of the dynamical generation of a quasiparticle band at the fermi energy as @xmath0 , and are a generic property of the strongly correlated hubbard model in all dimensions greater than one . . And you have already written the first three sentences of the full article: the discovery of high - t@xmath1 superconductors based on cuo - compounds @xcite has led to a large amount of theoretical work about the peculiar properties of these materials . a major effort has focussed on the normal - state properties of these compounds . this research was largely motivated and substantiated by experiments that revealed striking anomalies in the normal - state properties @xcite .. Please generate the next two sentences of the article

most prominent among these are the linear resistivity , a linear nmr - relaxation of the cu - spins , and a hall angle that behaves @xmath2 over a rather wide temperature region . furthermore , the optical conductivity shows a drude peak with a width@xcite @xmath3 , consistent with the linearity of the resistivity , and a drude weight which grows linearly with doping , consistent with the notion of holes acting as the charge carriers .

Suppose that you have an abstract for a scientific paper: in this paper the totally asymmetric exclusion process ( tasep ) with parallel update on an open lattice of size @xmath0 is considered in the maximum - current region . a formal expression for the generating function for the weight of configurations with @xmath1 particles is given . further an interpretation in terms of @xmath2-colored weighted motzkin paths is presented . using previous results ( woelki and schreckenberg 2009 _ j. stat . mech _ p05014 , woelki 2010 _ cellular automata _ , pp 637 - 645 ) the generating function is compared with the one for a possible 2nd - class particle dynamics for the parallel tasep . it is shown that both become physically equivalent in the thermodynamic limit . . And you have already written the first three sentences of the full article: one of the very rare exactly solvable non - equilibrium systems is the totally asymmetric simple exclusion process ( tasep ) , see @xcite and references therein . the model is defined on a 1d discrete lattice with @xmath0 sites that are either occupied by a single particle or empty . in the latter case they can be thought of as occupied by a single hole . in its version with parallel update. Please generate the next two sentences of the article

the tasep is equivalent to a special case of the nagel - schreckenberg model for traffic flow @xcite . here all bonds are updated simultaneously while in the original formulation , the random - sequential update , only one particle move can occur per infinitesimal time - step . in general , particles enter the lattice on site @xmath3 with probability @xmath4 and leave the lattice from site @xmath0 with probability @xmath5 . in between particles on sites

Suppose that you have an abstract for a scientific paper: we demonstrate the injection and transport of spin - polarized electrons through n - type doped silicon with in - plane spin - valve and perpendicular magnetic field spin precession and dephasing ( `` hanle effect '' ) measurements . a voltage applied across the transport layer is used to vary the confinement potential caused by conduction band - bending and control the dominant transport mechanism between drift and diffusion . by modeling transport in this device with a monte - carlo scheme , we simulate the observed spin polarization and hanle features , showing that the average transit time across the short si transport layer can be controlled over 4 orders of magnitude with applied voltage . as a result , this modeling allows inference of a long electron spin lifetime , despite the short transit length . . And you have already written the first three sentences of the full article: it has been a longstanding goal in semiconductor spintronics to inject , transport , manipulate , and detect spin - polarized carriers in silicon - based devices.@xcite despite great success in the field over the past ten years using other semiconductors such as gaas,@xcite the goal of achieving the same with si has been reached only recently , using all - electrical hot - electron methods with undoped single - crystal silicon transport layers.@xcite later , spin injection into silicon was realized as well in an epitaxially - grown silicon n - i - p diode structure using circular polarization analysis of weak electroluminescence spectra for spin detection across a transport layer of 80 - 140nm.@xcite although our previous studies demonstrate electron spin manipulation in undoped silicon - even over a very long distance ( 350 microns)@xcite - it is necessary to investigate magnetic- and electric - field control of electron spin in _ doped _ silicon for integration of spintronics into present - day silicon - based microelectronic technology , where impurity doping plays a critical role . in this report , we present spin injection , transport and detection in an n - type doped silicon device using our all - electrical methods .. Please generate the next two sentences of the article

unlike previous studies with undoped si , the presence of ionized impurities in the depletion regions of these doped transport layers gives rise to conduction band bending that for sufficient biasing conditions confines injected electrons for long dwell times . by modeling transport with drift and diffusion in the inhomogeneous electric fields provided by the band bending with a monte - carlo method , we simulate both spin precession and spin decay , showing that the transit time distribution of spin - polarized electrons can be controlled over a very wide range with an applied voltage , and can yield a measurement of spin lifetime . fig . [ fig1 ] illustrates the structure of our device .

Suppose that you have an abstract for a scientific paper: the specific heat of liquid helium was calculated theoretically in the landau theory @xcite . the results deviate from experimental data in the temperature region of 1.3 - 2.1 k. many theorists subsequently improved the results of the landau theory by applying temperature dependence of the elementary excitation energy @xcite , @xcite . as well known , many - body system has a total energy of galilean covariant form . therefore , the total energy of liquid helium has a nonlinear form for the number distribution function . the function form can be determined using the excitation energy at zero temperature and the latent heat per helium atom at zero temperature . the nonlinear form produces new temperature dependence for the excitation energy from bose condensate . we evaluate the specific heat using iteration method . the calculation results of the second iteration show good agreement with the experimental data in the temperature region of 0 - 2.1 k , where we have only used the elementary excitation energy at 1.1 k. . And you have already written the first three sentences of the full article: liquid helium system has a total hamiltonian as @xmath0 where @xmath1 is the mass of a helium atom , @xmath2 and @xmath3 respectively signify the creation and annihilation operators . we examine the general form of the total energy via the unitary transformation @xmath4 diagonalizing the hamiltonian @xmath5 . all eigenstates are described as @xmath6 where @xmath7 denotes the vacuum state .. Please generate the next two sentences of the article

new creation and annihilation operators are defined as @xmath8 which indicate the creation and annihilation operators of a quasi - particle . we designate this quasi - particle as a `` dressed boson '' .

Suppose that you have an abstract for a scientific paper: we present a numerical solution on a 5-dimensional spherically symmetric space time , in einstein - yang - mills - gauss - bonnet theory using a two point boundary value routine . it turns out that the gauss - bonnet contribution has a profound influence on the behaviour of the particle - like solution : it increases the number of nodes of the ym field . when a negative cosmological constant in incorporated in the model , it turns out that there is no horizon and no singular behaviour of the model . for positive cosmological constant the model has singular behaviour . . And you have already written the first three sentences of the full article: in recent years higher dimensional gravity is attracting much interest . one reason is the possibility that these higher dimensions could be detectable at cern . the possibility that space time may have more than four dimensions is initiated by high energy physics and inspired by d - brane ideology in string theory .. Please generate the next two sentences of the article

our 4-dimensional space time ( brane ) is embedded in the 5-dimensional bulk . it is assumed that all the standard model degrees of freedom reside on the brane , where as gravity can propagate into the bulk @xcite . the effect of string theory on classical gravitational physics is investigated by the low - energy effective action . if our 5-dimensional space time is obtained as an effective theory , the matter fields , for example the u(1 ) field , can exists in the bulk . in general relativity(gr ) , gravitating non - abelian gauge field , i.e. , the yang - mills(ym ) field , can be regarded as the most natural generalization of einstein - maxwell(em ) theory .

Suppose that you have an abstract for a scientific paper: we give the green function , momentum distribution , two - particle correlation function , and structure factor for the bound state of @xmath0 indistinguishable bosons with an attractive delta - function interaction in one dimension , and an argument showing that this boson `` molecule '' has no excited states other than dissociation into separated pieces . . And you have already written the first three sentences of the full article: consider a system of @xmath0 identical bosons in one dimension , with an attractive delta - function interaction . there is a bound state for all @xmath0 , having the form of a well - localized `` molecule''@xcite . this result is interesting , since it is the unique example of an exactly solved localized many - body system . a possible experimental realization of this system would be in a @xmath1 vapor @xcite confined to an atomic trap which is so tight in two directions , that the system can be regarded as one - dimensional with respect to the third direction .. Please generate the next two sentences of the article

such traps are realistic prospects in the near future @xcite , and high - aspect ratio cigar - shaped traps approximating quasi - one - dimensional systems are already available experimentally @xcite . we seek the localized eigenfunctions @xmath2x@xmath3 of the hamiltonian @xmath4 wherein @xmath5 is the particle mass and @xmath6 is a positive parameter representing the strength of interparticle attraction .

Suppose that you have an abstract for a scientific paper: we compare the way one of us got spinors out of fields , which are a priori antisymmetric tensor fields , to the dirac - k " ahler rewriting . since using our grassmann formulation is simple it may be useful in describing the dirac - k " ahler formulation of spinors and in generalizing it to vector internal degrees of freedom and to charges . the cheat concerning the lorentz transformations for spinors is the same in both cases and is put clearly forward in the grassmann formulation . also the generalizations are clearly pointed out . the discrete symmetries are discussed , in particular the appearance of two kinds of the time - reversal operators as well as the unavoidability of four families . . And you have already written the first three sentences of the full article: k " ahler@xcite has shown how to pack the dirac wave function into the language of differential forms in the sense that the dirac equation is an equation in which a linear operator acts on a linear combination @xmath0 of @xmath1-forms ( p=0 , 1 , ... , d ; here d = dimension = 4 ) . this is the dirac - k " ahler formalism . one of us@xcite has long developed an a priori rather different formalism in an attempt to unify spin and charges . in this approach. Please generate the next two sentences of the article

the spin degrees of freedom come out of canonically quantizing certain grassmannian odd ( position analogue in the sense of being on an analogue footing with @xmath2 ) variables @xmath3 . these variables are denoted by a vector index @xmath4 , and there are at first to see no spinors at all ! one of the main purposes of the present article is to point out the analogy and nice relations between the two different ways of achieving the - almost miraculous - appearance of spin one half degrees of freedom in spite of starting from pure vectors and tensors . of course it is a priori impossible that vectorial and tensorial fields ( or degrees of freedom ) can be converted into spinorial ones without some cheat . the

Suppose that you have an abstract for a scientific paper: this work reports on the magnetic reversal of sub-@xmath0 m sized elements consisting of an cofeb / ru / cofeb artificial ferrimagnet ( afi ) . the elements were patterned into ellipses having a width of approximately 250 to 270 nm and a varying aspect ratio between 1.3 and 8 . the coercivity was found to decrease with an increasing imbalance of the magnetic moment of the two antiferromagnetically coupled layers and is therefore strongly affected by an increase of effective anisotropy due to the antiferromagnetic coupling of the two layers . with respect to a single layer of amorphous cofeb , patterned in comparable elements , the afi has an increased coercivity . switching asteroids comparable to single layers were only observed for samples with a high net moment . . And you have already written the first three sentences of the full article: magnetic tunnel junctions ( mtj ) have gained considerable interest in recent years due to their high potential in various applications , e.g. as reads heads @xcite , angle @xcite or strain sensors @xcite and as programmable resistance in data storage ( mram ) @xcite or even magnetic logic devices @xcite . .,width=264 ] the underlaying concept is a spin valve consisting of a hard magnetic reference electrode separated from the soft magnetic sense or storage layer by a tunnel barrier like al@xmath1o@xmath2 . the reference layer usually is an artificial ferrimagnet ( afi ) exchange biased by a natural antiferromagnet , in which the afi consists of two ferromagnetic layers coupled antiparallel via a thin non - magnetic spacer . for the soft electrode ,. Please generate the next two sentences of the article

mostly single layers of polycrystalline material , e.g nife and cofe , have been used @xcite . recently , soft electrodes of polycrystalline afis , based on ferromagnetic materials like cofe and nife , have been investigated . they show a further reduction of the stray field due to the reduced net moment , smaller switching field distribution @xcite and an easier establishment of a single domain structure in patterned elements with small aspect ratio @xcite .

Suppose that you have an abstract for a scientific paper: in quantum computation , quantum coherence must be maintained during gate operation . however , in physical implementations , various couplings with the environment are unavoidable and can lead to a dephasing of a quantum bit ( qubit ) . the background charge fluctuations are an important dephasing process , especially in a charge qubit system . we examined the dephasing rate of a qubit due to random telegraph noise . solving stochastic differential equations , we obtained the dephasing rate of a qubit constructed of a coupled - dot system ; we applied our results to the charge josephson qubit system . we examined the dephasing rates due to two types of couplings between the coupled - dot system and the background charge , namely , fluctuation in the tunnel coupling constant and fluctuation in the asymmetric bias . for a strong coupling condition , the dephasing rate was inversely proportional to the time constant of the telegraph noise . when there is fluctuation in the tunnel coupling constant , gaussian decay occurs in the initial regime . we also examined the rate of dephasing due to many impurity sites . for a weak coupling condition with fluctuation in the asymmetric bias , the obtained dephasing rate coincided with that obtained by the perturbation method using the spectral weight of a boson thermal bath , which is proportional to the inverse of the frequency . 2 . And you have already written the first three sentences of the full article: efforts to implement quantum computation have recently intensified . the application of the quantum bit ( qubit ) to solid - state materials , such as superconducting josephson junctions @xcite and quantum dots @xcite , is particularly promising , because these implementations have the advantage of scalability . in a coupled - dot system , for example , the localized states in the left and right dots are treated as a basic two - level system , in which the tunnel coupling between the two dots constructs a quantum superposition of the dots .. Please generate the next two sentences of the article

this superposition manifests itself in coherent quantum oscillation ( rabi oscillation ) , and transition can be induced between the superposed states @xcite . a nanometer - scale superconducting electrode connected to a reservoir via a josephson junction constitutes an artificial two - level system in which the charge states , coupled by tunneling , differ by @xmath0 , where @xmath1 is the electronic charge .

Suppose that you have an abstract for a scientific paper: quantum correlations between two neighbor atoms are studied . it is assumed that one atomic system comprises a single auto - ionizing level and the other atom does not contain any auto - ionizing level . the excitation of both atoms is achieved by the interaction with the same mode of the quantized field . it is shown that the long - time behavior of two atoms exhibits quantum correlations even when the atoms do not interact directly . this can be shown using the optical excitation of the neighbor atom . also a measure of entanglement of two atoms can be applied after reduction of the continuum to two levels . . And you have already written the first three sentences of the full article: in the study of atoms with at least two electrons , bound states and resonances are of interest . the resonances evolve into states with one free electron after a very short time . this phenomenon is called auto - ionization of the atom . with a revival of interest in the auto - ionization. Please generate the next two sentences of the article

, fano published an appealing theoretical paper @xcite comprising an analysis of the excitation of the @xmath0 level of helium by electrons . he argued that the natural line shape contains a zero .

Suppose that you have an abstract for a scientific paper: we present a new algorithm to identify fragments in computer simulations of relativistic heavy ion collisions . it is based on the simulated annealing technique and can be applied to n - body transport models like the quantum molecular dynamics . this new approach is able to predict isotope yields as well as hyper - nucleus production . in order to illustrate its predicting power , we confront this new method to experimental data , and show the sensitivity on the parameters which govern the cluster formation . . And you have already written the first three sentences of the full article: in heavy ion reactions at energies between 20 a.mev and several a.gev , many clusters are formed . this cluster formation presents a big challenge for transport models in which nucleons are the degrees of freedom which are propagated . identifying clusters in a transport code which transports nucleons is all but simple and therefore in many approaches the fragment formation is simply omitted .. Please generate the next two sentences of the article

this invalidates the prediction of single particle observables as well , because the cluster formation and therefore the modification of the single particle spectra due to the fragment formation depends on the phase space region and , as a consequence , can not be approximated by a momentum independent scaling factor . the simplest way to identify clusters is by employing coalescence or a minimum spanning tree procedure .

Suppose that you have an abstract for a scientific paper: we present a source and lens reconstruction for the optical einstein ring gravitational lens system rxs j1131 - 1231 . we resolve detail in the source , which is the host galaxy of a @xmath0 quasar , down to a resolution of 0.045 arc seconds ( this is the size of the smallest conclusively resolved structures , rather than the pixel scale ) , using a bayesian technique with a realistic model for the prior information . the source reconstruction reveals a substantial amount of complex structure in the host galaxy , which is @xmath1 8 kpc in extent and contains several bright compact substructures , with the quasar source residing in one of these bright substructures . additionally , we recover the mass distribution of the lensing galaxy , assuming a simply - parameterised model , using information from both the quasar images and the extended images . this allows a direct comparison of the amount of information about the lens that is provided by the quasar images in comparison to the extended images . in this system , we find that the extended images provide significantly more information about the lens than the quasar images alone , especially if we do not include prior constraints on the central position of the lens . [ firstpage ] gravitational lensing methods : statistical galaxies : structure . And you have already written the first three sentences of the full article: gravitational lensing can be used as a powerful astrophysical tool for probing the density profiles of galaxies , and is one of the few ways in which dark matter can be detected ( e.g. * ? ? ? in addition , it often magnifies source objects by one to two orders of magnitude . this allows us to use the intervening gravitational lens as a kind of natural telescope , magnifying the source so that we can observe more detail than we would have been able to without the lens .. Please generate the next two sentences of the article

this extra magnification provided by lensing has been very beneficial to studies of star formation and galaxy morphology at high redshift . regions of the galaxy size and luminosity distribution that are inaccessible in unlensed observations are made ( more ) visible by lensing ( e.g. * ? ? ?

Suppose that you have an abstract for a scientific paper: observations of sun - like stars rotating faster than our current sun tend to exhibit increased magnetic activity as well as magnetic cycles spanning multiple years . using global simulations in spherical shells to study the coupling of large - scale convection , rotation , and magnetism in a younger sun , we have probed effects of rotation on stellar dynamos and the nature of magnetic cycles . major 3-d mhd simulations carried out at three times the current solar rotation rate reveal hydromagnetic dynamo action that yields wreaths of strong toroidal magnetic field at low latitudes , often with opposite polarity in the two hemispheres . our recent simulations have explored behavior in systems with considerably lower diffusivities , achieved with sub - grid scale models including a dynamic smagorinsky treatment of unresolved turbulence . the lower diffusion promotes the generation of magnetic wreaths that undergo prominent temporal variations in field strength , exhibiting global magnetic cycles that involve polarity reversals . in our least diffusive simulation , we find that magnetic buoyancy coupled with advection by convective giant cells can lead to the rise of coherent loops of magnetic field toward the top of the simulated domain . . And you have already written the first three sentences of the full article: global - scale magnetic fields and cycles of magnetic activity in sun - like stars are generated by the interplay of rotation and convection . at rotation rates greater than that of the current sun , such as when our sun was younger , observations tend to show increased magnetic activity indicating a strong global dynamo may be operating ( pizzolato et al . 2003 ) . here we explore large - scale dynamo action in sun - like stars rotating at three times the current solar rate , or @xmath0 , with a rotational period of 9.32 days . as shown by helioseismology ,. Please generate the next two sentences of the article

the solar interior is in a state of prominent differential rotation in the convection zone ( roughly the outer 30% by radius ) whereas the radiative interior is in uniform rotation . a prominent shear layer , or tachocline , is evident at the interface between the convective and radiative regions .

Suppose that you have an abstract for a scientific paper: we consider @xmath0boosting , a special case of friedman s generic boosting algorithm applied to linear regression under @xmath0-loss . we study @xmath0boosting for an arbitrary regularization parameter and derive an exact closed form expression for the number of steps taken along a fixed coordinate direction . this relationship is used to describe @xmath0boosting s solution path , to describe new tools for studying its path , and to characterize some of the algorithm s unique properties , including active set cycling , a property where the algorithm spends lengthy periods of time cycling between the same coordinates when the regularization parameter is arbitrarily small . our fixed descent analysis also reveals a _ repressible condition _ that limits the effectiveness of @xmath0boosting in correlated problems by preventing desirable variables from entering the solution path . as a simple remedy , a data augmentation method similar to that used for the elastic net is used to introduce @xmath0-penalization and is shown , in combination with decorrelation , to reverse the repressible condition and circumvents @xmath0boosting s deficiencies in correlated problems . in itself , this presents a new explanation for why the elastic net is successful in correlated problems and why methods like lar and lasso can perform poorly in such settings . . . And you have already written the first three sentences of the full article: given data @xmath1 , where @xmath2 is the response and @xmath3 is the @xmath4-dimensional covariate , the goal in many analyses is to approximate the unknown function @xmath5 by minimizing a specified loss function @xmath6 [ a common choice is @xmath0-loss , @xmath7 . in trying to estimate @xmath8 , one strategy is to make use of a large system of possibly redundant functions @xmath9 . if @xmath9 is rich enough , then it is reasonable to expect @xmath8 to be well approximated by an additive expansion of the form @xmath10 where @xmath11 are base learners parameterized by @xmath12 . to estimate @xmath8 , a joint multivariable optimization over @xmath13 may be used .. Please generate the next two sentences of the article

but such an optimization may be computationally slow or even infeasible for large dictionaries . overfitting may also result . to circumvent this problem , iterative descent

Suppose that you have an abstract for a scientific paper: we consider @xmath0 anosov diffeomorphisms on a compact riemannian manifold . we define the weak pseudo - physical measures , which include the physical measures when these latter exist . we prove that ergodic weak pseudo - physical measures do exist , and that the set of invariant probability measures that satisfy pesin s entropy formula is the weak@xmath1-closed convex hull of the ergodic weak pseudo - physical measures . in brief , we give in the @xmath0-scenario of uniform hyperbolicity , a characterization of pesin s entropy formula in terms of physical - like properties . 2010 _ math . subj . class . : _ primary 37a35 , 37d20 . secondary 37d35 ; 37a05 . _ keywords and phrases : _ anosov diffeomorphisms ; pesin s entropy formula ; physical measures . . And you have already written the first three sentences of the full article: the purpose of this paper is to give , in the @xmath0-scenario of uniform hyperbolicity , a characterization of those invariant measures that satisfy pesin s entropy formula in terms of their physical - like properties . our main result works , for @xmath0 anosov diffeomorphisms , as ledrappier - young characterization @xcite of the measures @xmath2 that satisfy pesin s entropy formula ( which holds in the @xmath3 context but not in the general @xmath0 context ) , by substituting the property of absolute continuity of the unstable conditional decomposition of @xmath2 , by the weak pseudo - physical property of its ergodic decomposition . pesin theory @xcite gives relevant tools and results of the modern differentiable ergodic theory .. Please generate the next two sentences of the article

it works for @xmath3 ( or at least @xmath0 plus hlder ) dynamical systems . for instance , for @xmath3 hyperbolic systems , pesin s entropy formula computes exactly the metric entropy of a diffeomorphism in terms of the mean value of the sum of its positive lyaypunov exponents . in the @xmath3 scenario ,

Suppose that you have an abstract for a scientific paper: based on the truncated dyson - schwinger equations for fermion and massive boson propagators in qed@xmath0 , the fermion chiral condensate and the mass singularities of the fermion propagator via the schwinger function are investigated . it is shown that the critical point of chiral phase transition is apparently different from that of deconfinement phase transition and in nambu phase the fermion is confined only for small gauge boson mass . . And you have already written the first three sentences of the full article: the chiral and deconfinement phase transitions of nonperaturbative systems are important issues of continuous interests both theoretically and experimentally . although the mechanism is unknown , the originally chiral symmetric system may undergo chiral phase transition ( cpt ) into a phase with dynamical chiral symmetry breaking ( dcsb ) which explains the origin of constituent - quark masses in qcd and underlies the success of chiral effective field theory @xcite . in the chiral limit , the order parameter of cpt is defined via the fermion propagator @xmath1=\int\frac{\mathrm{d}^dp}{(2\pi)^d}\frac{4b(p^2)}{a^2(p^2)p^2+b^2(p^2)}.\ ] ] the two functions @xmath2 and @xmath3 in the above equation are related to the inverse fermion propagator @xmath4 the deconfinement phase transition is then related to the observation of the free particle and also the corresponding propagator . if the full fermion propagator has no mass singularity in the timelike region , it can never be on mass shell and the free particle can never be observed where the confinement happens @xcite . accordingly , the appearance of the mass singularity in the system directly implies deconfinement .. Please generate the next two sentences of the article

so in this way we can learn the deconfinement phase transition from the analytic structure of the fermion propagator . to indicate dcsb and confinement , it is very suggestive to study some model that reveals the general nonperaturbative features while being simpler .

Suppose that you have an abstract for a scientific paper: we report the results of magnetic measurements on a powder sample of nicu(pba)(d@xmath0o)@xmath1@xmath22d@xmath0o ( pba=1,3-propylenebis(oxamato ) ) which is one of the prototypical examples of an @xmath3=1/2 and 1 ferrimagnetic chain . susceptibility(@xmath4 ) shows a monotonous increase with decreasing temperature ( t ) and reaches a maximum at about 7 k. in the plot of @xmath4@xmath5 versus @xmath6 , the experimental data exhibit a broad minimum and are fit to the @xmath4@xmath5 curve calculated for the ferrimagnetic heisenberg chain composed of @xmath3=1/2 and 1 . from this fit , we have evaluated the nearest - neighbor exchange constant @xmath7=121 k , the g - values of ni@xmath8 and cu@xmath8 , @xmath9=2.22 and @xmath10=2.09 , respectively . applied external field dependence of @xmath4@xmath5 at low temperatures is reproduced fairly well by the calculation for the same ferrimagnetic model . extensive studies of one - dimensional systems were prompted by haldane s theoretical work @xcite in 1983 after the initial wave of studies @xcite in the late 1960s and early 1970s . recently , quantum spin systems with singlet ground states , namely haldane systems @xcite ( linear chain heisenberg antiferromagnets with integer spin values ) , inorganic spin - peierls systems @xcite and even - leg spin ladder systems , @xcite have been studied extensively . in particular , cuprate systems have attracted much attention because of the relation to high @xmath11 superconductors . in regard to the one - dimensional systems with magnetic ground states , an @xmath3=1/2 and 1 ferrimagnetic chain has been theoretically investigated recently , @xcite in addition to some pioneering theoretical works @xcite published in the 1980s . from the low dimensionality and small spin values in this system , we expect a kind of quantum effect . theoretical studies show some remarkable features as follows : ( 1 ) between two low - lying , gapless and gapped excitation branches , the gapped branch lies higher than.... And you have already written the first three sentences of the full article: this work was carried out under the visiting researcher@xmath31s program of kyokugen at osaka university and was supported in part by a grand - in - aid for scientific research from the ministry of education , science , sports and culture . m.h . would like to thank professor k. nonoyama of konan women@xmath31s junior college for information about the synthesis of na@xmath0[cu(pba)]@xmath26h@xmath0o and professor s. yamamoto of okayama university for fruitful discussions . thanks are also due to the chemical analysis units in riken . 99 f. d. m. haldane : phys . rev .. Please generate the next two sentences of the article

* 50 * ( 1983 ) 1153 . l. j. de jongh and a. r. miedema : adv .

Suppose that you have an abstract for a scientific paper: we have developed an inversion method for determination of the characteristics of the acceleration mechanism directly and non - parametrically from observations , in contrast to the usual forward fitting of parametric model variables to observations . in two recent papers @xcite , we demonstrate the efficacy of this inversion method by its application to acceleration of electrons in solar flares based on stochastic acceleration by turbulence . here we explore its application for determining the characteristics of shock acceleration in supernova remnants ( snrs ) based on the electron spectra deduced from the observed nonthermal radiation from snrs and the spectrum of the cosmic ray electrons observed near the earth . these spectra are related by the process of escape of the electrons from snrs and energy loss during their transport in the galaxy . thus , these observations allow us to determine spectral characteristics of the momentum and pitch angle diffusion coefficients , which play crucial roles in both direct acceleration by turbulence and in high mach number shocks . assuming that the average electron spectrum deduced from a few well known snrs is representative of those in the solar neighborhood we find interesting discrepancies between our deduced forms for these coefficients and those expected from well known wave - particle interactions . this may indicate that the standard assumptions made in treatment of shock acceleration need revision . in particular , the escape of particles from snrs may be more complex than generally assumed . . And you have already written the first three sentences of the full article: acceleration of charge particles in the universe happens on scales from planetary magnetospheres to clusters of galaxies and at energies ranging from nonrelativistic values to @xmath010@xmath1 ev ultra high energy cosmic rays ( uhecrs ) . the particles are observed directly as cosmic rays ( crs ) , solar energetic particles , or indirectly by their interactions with background matter and electromagnetic fields ( magnetic fields and photons ) , which give rise to heating and ionization of the plasma , and nonthermal radiation extending from long wavelength radio to @xmath0tev gamma - rays . in spite of more than a century of observations , the exact mechanism of acceleration is still being debated and the detailed model parameters are poorly constrained .. Please generate the next two sentences of the article

clearly electric fields are involved in any acceleration mechanism . large scale electric fields have been found to be important in some unusual astrophysical sources such as magnetospheres of neutron stars ( pulsars and perhaps magnetars ) and in so - called double - layers . however , here we are interested in commonly considered mechanisms based on the original fermi process @xcite , which involves scattering of particles by fluctuating electric and magnetic fields ( or plasma turbulence ) or converging flows as in shocks .

Suppose that you have an abstract for a scientific paper: several galaxies , such as dwarfs and irregulars as well as outer galactic clouds have low metallicity . at low metallicities a reduction in the amount of dust and heavy elements plays a significant role on the chemistry as well as the heating and cooling of the gas in the molecular regions , called as photon dominated regions ( pdrs ) . we present here the effects of reduced metallicity in pdrs and study the important pdr cooling lines ( [ cii ] , [ ci ] and co ) . moreover many observational evidences suggest that molecular clouds are clumpy . we model the molecular emission from galaxies incorporating a mass spectrum of clumps . we also compare our results with the semi - analytical results obtained by bolatto et al . ( 1999 ) . . And you have already written the first three sentences of the full article: photon dominated regions are predominantly molecular and atomic regions where the physical and chemical processes are dominated by uv radiation ( cf . hollenbach & tielens , 1997 , 1999 ) . the molecular clouds in the vicinity of the newly formed stars is heated by the fuv photons in the energy range from about 6 to 13.6ev . these clouds cool through the atomic and molecular spectral lines , such as [ cii]158@xmath0 , [ oi]63,146@xmath0 , [ ci]609,370@xmath0 and the milli - metric and sub - mm co rotational lines .. Please generate the next two sentences of the article

plane parallel and spherical models of pdrs have been constructed to understand the physical and chemical characteristics of these regions ( e.g. , kaufman et al . , 1999 ; kster et al . , 1994 ; le bourlot et al . ,

Suppose that you have an abstract for a scientific paper: to investigate feedback between relativistic jets emanating from active galactic nuclei ( agn ) and the stellar population of the host galaxy , we analyze the long - term evolution of the galaxy - scale simulations by @xcite of jets in massive , gas - rich galaxies at @xmath0 and of stars formed in the host galaxies . we find strong , jet - induced differences in the resulting stellar populations of galaxies that host relativistic jets and galaxies that do not , including correlations in stellar locations , velocities , and ages . jets are found to generate distributions of increased radial and vertical velocities that persist long enough to effectively extend the stellar structure of the host . the jets cause the formation of bow shocks that move out through the disk , generating rings of star formation within the disk . the bow shock often accelerates pockets of gas in which stars form , yielding populations of stars with significant radial and vertical velocities , some of which have large enough velocities to escape the galaxy . these stellar population signatures can serve to identify past jet activity as well as jet - induced star formation . . And you have already written the first three sentences of the full article: the impact that active galactic nuclei ( agn ) have on their hosts is one of the most critical components of galaxy formation theory @xcite . observationally , astronomers find fewer luminous galaxies than expected based on the evolution of a @xmath1cdm universe and frequently attribute this phenomenon to agn quenching of star formation @xcite , ultimately reducing the number of bright galaxies . some cosmological simulations use the injection of thermal energy or mechanical heating into the center of galaxies as a prescription for agn feedback ( e.g. * ? ? ?. Please generate the next two sentences of the article

* ; * ? ? ? * ) , and often derive luminosity functions that match up better with observations . however , the physical processes in agn feedback are far more complex than the introduction of heating processes .

Suppose that you have an abstract for a scientific paper: we investigated the typical time scales of the kondo correlations formation for the single - state anderson model , when coupling to the reservoir is switched on at the initial time moment . the influence of the kondo effect appearance on the system non - stationary characteristics was analyzed and discussed . . And you have already written the first three sentences of the full article: non - stationary effects now a days attract much attention and are vital both from fundamental and technological points of view . first of all , non - stationary characteristics provide more information about the properties of nanoscale systems comparing to the stationary ones . moreover , modern electronic devices design with particular set of transport parameters requires careful analysis of non - stationary effects , transient processes and time evolution of charge and spin states prepared at the initial time moment @xcite,@xcite,@xcite,@xcite,@xcite,@xcite .. Please generate the next two sentences of the article

correct analysis of the non - stationary dynamics of @xmath0local@xmath0 magnetic moment and electron occupation numbers of the correlated anderson impurity coupled to reservoir requires the investigation of the kondo correlations influence on the system time evolution . it is necessary to clarify the question how the relaxation rates of @xmath0local@xmath0 magnetic moment and charge density change with the appearance of the kondo correlations .

Suppose that you have an abstract for a scientific paper: we report on very high energy ( e @xmath0 100 gev ) gamma - ray observations of v407 cygni , a symbiotic binary that underwent a nova outburst producing 0.110 gev gamma rays during 2010 march 1026 . observations were made with the very energetic radiation imaging telescope array system during 2010 march 1926 at relatively large zenith angles , due to the position of v407 cyg . an improved reconstruction technique for large zenith angle observations is presented and used to analyze the data . we do not detect v407 cygni and place a differential upper limit on the flux at 1.6 tev of @xmath1 ( at the 95% confidence level ) . when considered jointly with data from _ fermi_-lat , this result places limits on the acceleration of very high energy particles in the nova . . And you have already written the first three sentences of the full article: in march of 2010 , the _ fermi_-lat collaboration announced a new gev transient in the galactic plane , fgl j2102 + 4542 , that was identified as a nova outburst in the symbiotic binary v407 cygni ( hereafter , v407 cyg ) . at least seven gev transients located near the galactic plane have been discovered by egret , _ fermi_-lat and agile .. Please generate the next two sentences of the article

only two have been identified at other wavelengths : v407 cyg , which is the first nova to be detected at gev energies , and j0109 + 6134 , which was likely a background blazar @xcite . the physical nature of the other five sources is unknown @xcite , and some of these gev transients may represent a new class of gamma - ray emitting objects . the _ fermi_-lat collaboration reported variable gamma - ray emission in the 0.110 gev band from fgl j2102 + 4542 during 2010 march 1026 ( mjd 5526555281 ) @xcite .

Suppose that you have an abstract for a scientific paper: the ground state phases of a one - dimensional su(4 ) spin - orbital hamiltonian in a generalized external field are studied on the basis of bethe - ansatz solution . introducing three land @xmath0 factors for spin , orbital and their products in the su(4 ) zeeman term , we discuss systematically the various symmetry breaking . the magnetization versus external field are obtained by solving bethe - ansatz equations numerically . the phase diagrams corresponding to distinct residual symmetries are given by means of both numerical and analytical methods . . And you have already written the first three sentences of the full article: there have been much interest in the study of spin models with orbital degeneracy @xcite due to experimental progress related to many transition - metal and rare - earth compounds such as lamno@xmath1 , ceb@xmath2 , and perovskite lattice , as in kcuf@xmath1@xcite . those systems involve orbital degree of freedom in addition to spin ones . almost three decades ago , kugel and khomskii@xcite had pointed out the possibility of orbital excitations in these systems . as a model system. Please generate the next two sentences of the article

, it exhibits some fascinating physical features which is lack without orbital degree of freedom . the isotropic case of spin system with orbital degeneracy was shown to have an enlarged su(4 ) symmetry @xcite , and one dimensional model is known to exactly solvable @xcite .

Suppose that you have an abstract for a scientific paper: a study of the reaction @xmath0 has been performed in the energy range of 18 44 mev . total cross sections and differential cross sections at six angles have been measured at 15 energies with an energy increment of 1 2 mev . this is the most systematic data set in this energy range . no structure in the energy dependence of the cross section has been observed within the accuracy of this experiment . . And you have already written the first three sentences of the full article: total and differential cross sections for the reaction @xmath1 have been measured with high accuracy at pion energies above 100 mev . currently , experimental efforts in this energy range are aimed at measuring spin dependent observables . the situation at pion energies below 100 mev is less complete , especially for energies of a few tens of mev@xcite .. Please generate the next two sentences of the article

the disagreement between the experimental data for the total cross section in some cases exceeds 20% , much larger than the quoted uncertainties . the experimental data show a deviation from smooth behavior in the total cross section of the reaction @xmath2 close to @xmath3 ( @xmath4)@xcite . more recent measurements of the partial total cross section for the inverse reaction at saturne have verified this effect@xcite . in a recent experiment of the dubna - gatchina group on pion absorption on carbon@xcite a dip in the energy dependence of the quasi - deuteron component of absorption near @xmath5=28 mev has been observed .

Suppose that you have an abstract for a scientific paper: in this paper , we analyze the structure of rrab star light curves using principal component analysis . we find this is a very efficient way to describe many aspects of rrab light curve structure : in many cases , a principal component fit with 9 parameters can describe a rrab light curve including bumps whereas a 17 parameter fourier fit is needed . as a consequence we show show statistically why the amplitude is also a good summary of the structure of these rr lyrae light curves . we also use our analysis to derive an empirical relation relating absolute magnitude to light curve structure . in comparing this formula to those derived from exactly the same dataset but using fourier parameters , we find that the principal component analysis approach has distinct advantages . these advantages are , firstly , that the errors on the coefficients multiplying the fitted parameters in such formulae are much smaller , and secondly , that the correlation between the principal components is significantly smaller than the correlation between fourier amplitudes . these two factors lead to reduced formal errors , in some cases estimated to be a factor of 2 , on the eventual fitted value of the absolute magnitude . this technique will prove very useful in the analysis of data from existing and new large scale survey projects concerning variable stars . rr lyraes stars : fundamental parameters . And you have already written the first three sentences of the full article: kanbur et al ( 2002 ) , hendry et al ( 1999 ) , tanvir et al ( 2004 ) introduced the use of principal component analysis ( pca ) in studying cepheid light curves . they showed that a major advantage of such an approach over the traditional fourier method is that it is much more efficient : an adequate fourier description requires , at best , a fourth order fit or 9 parameters , whilst a pca analysis requires only 3 or 4 parameters with as much as 81@xmath0 of the variation in light curve structure being explained by the first parameter . later , leonard et al ( 2003 ) used the pca approach to create cepheid light curve templates to estimate periods and mean magnitudes for hst observed cepheids .. Please generate the next two sentences of the article

the purpose of this paper is to apply the pca technique to the study of rr lyrae light curves . the mathematical formulation and error characteristics of pca are given in k02 and will only be summarized here .

Suppose that you have an abstract for a scientific paper: we report on a survey devoted for the search of exo - planets around young and nearby stars carried out with naco at the vlt . the detection limit for @xmath0 among the best available targets vs. the angular separation from the star is presented . the non - detection of any planetary mass companion in our survey is used to derive , for the first time , the frequency of the upper limit of the projected separation planet - stars . in particular , we find that in @xmath1@xmath2 of cases , no @xmath3m@xmath4 planet ( or more massive ) has been detected at projected separations larger than @xmath5 au and no @xmath6m@xmath4 planet ( or more massive ) has been detected at projected separations larger than @xmath7 au . in @xmath8@xmath2 of cases , these values increase to @xmath9 au and @xmath10 au respectively . the excellent sensitivity reached by our study leads to a much lower upper limit of the projected planet - star separation compared with previous studies . for example , for the @xmath11 pictoris group , ( @xmath12@xmath13 myr ) , we did not detect any @xmath6m@xmath4 planet at distances larger than @xmath14 au . a previous study carried out with @xmath15 m class telescopes put an upper limit for @xmath6m@xmath4 planets at @xmath12@xmath16 au . for our closest target ( v@xmath17 oph - d = @xmath18 pc ) it is shown that it would be possible to detect a @xmath6m@xmath4 planet at a minimum projected separation from the star of @xmath19 au and a @xmath3m@xmath4 planet at a minimum projected separation of @xmath20 au . our results are discussed with respect to mechanisms explaining planet formation and migration and to forthcoming observational strategies and future planet finder observations from the ground . . And you have already written the first three sentences of the full article: at the present time more than @xmath8 exo - planets are known which have been mostly discovered by the indirect method of the variation of the radial velocity induced by planets orbiting around the central star . it can be shown that young planets can be detected with adaptive optics ( ao ) imaging techniques at @xmath21-@xmath6 meter telescopes if they are sufficiently distant from their parent star . since it is reasonable to assume a coevality between the parent star and the planet , we can retrieve from atmospherical models ( burrows et al .. Please generate the next two sentences of the article

1997 , baraffe et al . 2003 ) that planets having a mass in the range @xmath22-@xmath6 m@xmath4 and orbiting around young late - type stars ( @xmath6-@xmath23 myr ) have a typical brightness contrast with respect to the parent star of the order of @xmath24-@xmath25 , corresponding to a magnitude difference of @xmath26 of @xmath3-@xmath14 mag . this means that a planet can be detected at a few tens of aus from parent stars having distances @xmath27 @xmath1 pc .

Suppose that you have an abstract for a scientific paper: a new type of object called very low luminosity objects ( vellos ) " has been discovered by the spitzer space telescope . vellos might be substellar objects forming by accretion . however , some vellos are associated with strong outflows , indicating the previous existence of massive accretion . the thermal history , which significantly affects the chemistry , between substellar objects with a continuous low accretion rate and objects in a quiescent phase after massive accretion ( outburst ) must be greatly different . in this study , the chemical evolution has been calculated in an episodic accretion model to show that co and n@xmath0h@xmath1 have a relation different from starless cores or class 0/i objects . furthermore , the co@xmath0 ice feature at 15.2 @xmath2 m will be a good tracer of the thermal process in vellos . . And you have already written the first three sentences of the full article: the _ spitzer space telescope ( sst ) _ , with its very high mid - infrared sensitivity , has revealed a new type of low - mass protostars called very low luminosity objects ( vellos ; e.g. , young et al . 2004 ) . defining the internal luminosity of a source , , to be the total luminosity of the central protostar and circumstellar disk ( if present ) , a vello is defined to be an object embedded within a dense core that meets the criterion @xmath3 0.1 ( di francesco et al . 2007 ) .. Please generate the next two sentences of the article

vellos are primarily being discovered in cores previously classified as starless based on observations with the _ infrared astronomical satellite ( iras ) _ and the _ infrared space observatory ( iso)_. the three most well - studied vellos to date are iram 04191 ( andr et al . 1999 ; dunham et al . 2006 ) , l1014 ( young et al . 2004

Suppose that you have an abstract for a scientific paper: we briefly review the hadronization pictures adopted in the lund string fragmentation model(lsfm ) , webber cluster fragmentation model(wcfm ) and quark combination model(qcm ) , respectively . predictions of hadron multiplicity , baryon to meson ratios and baryon - antibaryon flavor correlations , especially related to heavy hadrons at @xmath0 factory obtained by lsfm and qcm are reported . + * keywords : * @xmath0 factory ; hadronization model ; baryon to meson ratio ; @xmath1 correlation + * pacs : * 12.15.ji , 13.38.dg , 24.10.lx . And you have already written the first three sentences of the full article: the hadronization mechanism is an important but still unsolved problem up to now due to its nonperturbative nature . it is recognized that the hadronization mechanism is universal in all kinds of high energy reactions , _ e.g_. , @xmath2 annihilation , and hadron(nuclear)-hadron(nuclear ) collisions . among these reactions , @xmath2 annihilation at high energies , especially at the @xmath0 factory in the future , is best for studying the hadronization mechanism , since all the final hadrons come from primary ones , all of which are hadronization results . the @xmath3 process is generally divided into four phases ( see fig .. Please generate the next two sentences of the article

[ hdpro ] ) . 1 . in the electro - weak phase , @xmath4 pair converts into a primary quark pair @xmath5 via virtual photon or @xmath6 . this phase is described by the electro - weak theory .

Suppose that you have an abstract for a scientific paper: bi@xmath0te@xmath1 and bi@xmath0se@xmath1 are well known 3d - topological insulators . films made of these materials exhibit metal - like surface states with a dirac dispersion and possess high mobility . the high mobility metal - like surface states can serve as channel material for ti - based field effect transistors . while such a transistor offers superior terminal characteristics , they suffer from an inherent zero band gap problem . the absence of a band gap for the surface states prevents an easy turn - off mechanism . in this work , techniques that can be employed to easily open a band gap for the ti surface states is introduced . two approaches are described : 1 ) coating the surface states with a ferromagnet which has a controllable magnetization axis . the magnetization strength of the ferromagnet is incorporated as an exchange interaction term in the hamiltonian . 2 ) an _ s_-wave superconductor , because of the proximity effect , when coupled to a 3d - ti opens a band gap on the surface . this ti - superconductor heterostructure is modeled using the bogoliubov - de gennes hamiltonian . a comparison demonstrating the finite size effects on surface states of a 3d - ti and edge states of a cdte / hgte / cdte - based 2d - ti is also presented . 3d - ti nanostructures can be reduced to dimensions as low as 10.0 @xmath2 in contrast to 2d - ti structures which require a thickness of at least 100.0 @xmath2 . all calculations are performed using the continuum four - band k.p hamiltonian . . And you have already written the first three sentences of the full article: topological insulators ( ti ) are a new class of materials whose surfaces / edges host bound spin - polarized dirac fermions with high mobility . these states , in a time reversal invariant system are protected against perturbation and non - magnetic disorder . @xcite well - known examples of materials with such properties include bi@xmath0te@xmath1 , bi@xmath0se@xmath1 , sb@xmath0te@xmath1 , bi@xmath3sb@xmath4 alloy , and the cdte / hgte / cdte quantum well heterostructure .. Please generate the next two sentences of the article

bi@xmath0te@xmath1 , bi@xmath0se@xmath1 , sb@xmath0te@xmath1 , and bi@xmath3sb@xmath4 alloy belong to the class of 3d topological insulators ( 3d ti ) @xcite and host bound states on their surface . these states are characterized by a linear hamiltonian and form a band - gap closing dirac cone on each surface at the @xmath5 point . in this work , methods that alter the surface state dispersion through proximity induced ferromagnetism , superconductivity , and

Suppose that you have an abstract for a scientific paper: outer envelopes of neutron stars consist mostly of fully ionized , strongly coupled coulomb plasmas characterized by typical densities @xmath0@xmath1 and temperatures @xmath2@xmath3 k. many neutron stars possess magnetic fields @xmath4@xmath5 g. recent theoretical advances allow one to calculate thermodynamic functions and electron transport coefficients for such plasmas with an accuracy required for theoretical interpretation of observations . . And you have already written the first three sentences of the full article: envelopes of neutron stars ( nss ) are divided in the inner and outer envelopes . properties of the inner envelopes are outlined in a companion paper @xcite . here we focus on the outer ones , at typical densities @xmath6 and temperatures @xmath7 k. these envelopes are relatively thin , but they affect significantly ns evolution . in particular , they provide thermal insulation of stellar interiors .. Please generate the next two sentences of the article

bulk properties of the ns envelopes ( pressure @xmath8 , internal energy @xmath9 ) are determined mainly by degenerate electron gas . the electrons are relativistic at @xmath10 , where @xmath11 , @xmath12 is the fermi wave number , @xmath13 is the electron mass , @xmath14 is the electron number density , @xmath15 , @xmath16 and @xmath17 are the ion charge and mass numbers , respectively .

Suppose that you have an abstract for a scientific paper: the model under consideration is based on approximate analytical solution of two dimensional stationary navier - stokes and fourier - kirchhoff equations . approximations are based on the typical for natural convection assumptions : the fluid noncompressibility and bousinesq approximation . we also assume that ortogonal to the plate component ( @xmath0 ) of velocity is neglectible small . the solution of the boundary problem is represented as a taylor series in @xmath0 coordinate for velocity and temperature which introduces functions of vertical coordinate ( @xmath1 ) , as coefficients of the expansion . the correspondent boundary problem formulation depends on parameters specific for the problem : grashoff number , the plate height ( @xmath2 ) and gravity constant . the main result of the paper is the set of equations for the coefficient functions for example choice of expansion terms number . the nonzero velocity at the starting point of a flow appears in such approach as a development of convecntional boundary layer theory formulation . . And you have already written the first three sentences of the full article: a conventional boundary layer theory of fluid flow used for free convective description assumes zero velocity at leading edge of a heated plate . more advanced theories of self - similarity also accept this same boundary condition @xcite , @xcite , @xcite . however experimental visualization definitely shows that in the vicinity of edge the fluid motion exists sb , @xcite , @xcite .. Please generate the next two sentences of the article

it is obvious from the point of view of the mass conservation law . in the mentioned convection descriptions the continuity equation is not taken into account that diminishes the number of necessary variables .

Suppose that you have an abstract for a scientific paper: a quantitative theory of spectral lags for @xmath0-ray bursts ( grbs ) is given . the underlying hypothesis is that grb subpulses are photons that are scattered into our line of sight by local concentrations of baryons that are accelerated by radiation pressure . for primary spectra that are power laws with exponential cutoffs , the width of the pulse and its fast rise , slow decay asymmetry is found to increase with decreasing photon energy , and the width near the exponential cutoff scales approximately as @xmath1 , with @xmath2 , as observed . the spectral lag time is naturally inversely proportional to luminosity , all else being equal , also as observed . . And you have already written the first three sentences of the full article: the fast rise , slow decay of subpulses in grb is a common feature . there could be many ways to explain it ( e.g. impulsive energy infusion followed by slower cooling or light echoing ) . it is therefore desirable to discriminate among the different models with quantitative tests and predictions whenever possible . in a previous paper ( eichler and manis 2007 , hereafter em07 ) , it was suggested that fast rise , slow decay subpulses constitute a qualitative manifestation of baryons being accelerated by radiation pressure .. Please generate the next two sentences of the article

more generally , the basic idea can apply to any flow in which a light , fast fluid imparts energy to a clumpy , denser component of the flow by overtaking the clumps from the rear , but for convenience in this discussion we refer to the fast light component as photons that scatter off the clumps . it was proposed that the fast rise of a subpulse is the stage where a cloud of baryons scatters photons into a progressively narrowing beaming cone of width @xmath3 , where @xmath4 is the bulk lorentz factor of the accelerating cloud .

Suppose that you have an abstract for a scientific paper: in recent years argument has been made that a high fraction of early - type galaxies in the local universe experience low levels ( @xmath0 ) of star formation ( sf ) that causes strong excess in uv flux , yet leaves the optical colors red . many of these studies were based on _ galex _ imaging of sdss galaxies ( @xmath1 ) , and were thus limited by its @xmath2 fwhm . poor uv resolution left other possibilities for uv excess open , such as the old populations or an agn . here we study high - resolution far - ultraviolet _ hst_/acs images of optically quiescent early - type galaxies with strong uv excess . the new images show that three - quarters of these moderately massive ( @xmath3 ) early - type galaxies shows clear evidence of extended sf , usually in form of wide or concentric uv rings , and in some cases , striking spiral arms . sdss spectra probably miss these features due to small fiber size . uv - excess early - type galaxies have on average less dust and larger uv sizes ( @xmath4 kpc ) than other green - valley galaxies , which argues for an external origin for the gas that is driving the sf . thus , most of these galaxies appear ` rejuvenated ' ( e.g. , through minor gas - rich mergers or igm accretion ) . for a smaller subset of the sample , the declining sf ( from the original internal gas ) can not be ruled out . sf is rare in very massive early - types ( @xmath5 ) , a possible consequence of agn feedback . in addition to extended uv emission , many galaxies show a compact central source , which may be a weak , optically inconspicuous agn . . And you have already written the first three sentences of the full article: in this paper we present a discovery of significantly extended regions of star formation in some early - type galaxies ( etgs)galaxies usually thought to lie on the passive side of galaxy bimodality . bimodality in terms of morphology and color has been known since the earliest studies of galaxies , but it was not until the massive datasets of the sloan digital sky survey ( sdss ) that fuller implications in terms of galaxy evolution became evident @xcite . optical colors reflect the mean age of stellar populations and are therefore sensitive only to high levels of continuous sf @xcite .. Please generate the next two sentences of the article

if the sfr per unit stellar mass ( specific sfr ) drops below some threshold , optical colors become uniformly red and sdss photometry can not distinguish a truly passive galaxy from one that also contains a young population . these limitations are alleviated when ultraviolet ( uv ) photometry , dominated by young stars , is available .

Suppose that you have an abstract for a scientific paper: in this paper we prove a sharp distortion property of the cassinian metric under mbius transformations of a punctured ball onto another punctured ball . the paper also deals with discussion on local convexity properties of the cassinian metric balls in some specific subdomains of @xmath0 . inclusion properties of the cassinian metric balls with other hyperbolic - type metric balls are also investigated . in particular , several conjectures are also stated in response to sharpness of the inclusion relations . + * 2010 mathematics subject classification*. 30c35 , 30c20 , 30f45 , 51m10 . * keywords and phrases . * mbius transformations , cassinian metric , distortion property , inclusion property , metric balls , convexity . . And you have already written the first three sentences of the full article: conformal invariants have important roles in geometric function theory . one of the basic conformal invariants is the modulus of a curve family , which is used to define quasiconformal maps @xcite . in euclidean spaces of dimension more than two , conformal maps are nothing but the restrictions of mbius maps ; for instance , see @xcite .. Please generate the next two sentences of the article

therefore , it is natural to study mbius invariants in the higher dimensional setting . there are some metrics which are mbius invariant and some are not .

Suppose that you have an abstract for a scientific paper: we revisit the schwinger effect in de sitter , anti - de sitter spaces and charged black holes , and explore the interplay between quantum electrodynamics and the quantum gravity effect at one - loop level . we then advance a thermal interpretation of the schwinger effect in curved spacetimes . finally , we show that the schwinger effect in a near - extremal black hole differs from hawking radiation of charged particles in a non - extremal black hole and is factorized into those in an anti - de sitter space and a rindler space with the surface gravity for acceleration . . And you have already written the first three sentences of the full article: spontaneous creation of particles or charged pairs from an external gauge field or a curved spacetime is one of the most prominent phenomena in quantum field theory . a strong electric field produces pairs of charged particles and antiparticles , known as the schwinger mechanism @xcite . the more remarkable phenomenon is the emission of all species of particles from black holes , known as hawking radiation @xcite . under an influence of strong backgrounds. Please generate the next two sentences of the article

the vacuum may spontaneously breakdown due to quantum fluctuations and virtual pairs can be separated either by the energy of the fields or the causality of spacetimes . an accelerating detector measures a thermal spectrum of the unruh temperature determined by the acceleration , known as the unruh effect.@xcite the spectrum and characteristics for these effects are summarized in table [ ta1 ] .

Suppose that you have an abstract for a scientific paper: we introduce a family of fourth order two - step methods that preserve the energy function of canonical polynomial hamiltonian systems . each method in the family may be viewed as a correction of a linear two - step method , where the correction term is @xmath0 ( @xmath1 is the stepsize of integration ) . the key tools the new methods are based upon are the line integral associated with a conservative vector field ( such as the one defined by a hamiltonian dynamical system ) and its discretization obtained by the aid of a quadrature formula . energy conservation is equivalent to the requirement that the quadrature is exact , which turns out to be always the case in the event that the hamiltonian function is a polynomial and the degree of precision of the quadrature formula is high enough . the non - polynomial case is also discussed and a number of test problems are finally presented in order to compare the behavior of the new methods to the theoretical results . ordinary differential equations , mono - implicit methods , multistep methods , canonical hamiltonian problems , hamiltonian boundary value methods , energy preserving methods , energy drift . 65l05 , 65p10 . . And you have already written the first three sentences of the full article: we consider canonical hamiltonian systems in the form @xmath2 where @xmath3 is a smooth real - valued function . our interest is in researching numerical methods that provide approximations @xmath4 to the true solution along which the energy is precisely conserved , namely @xmath5 the study of energy - preserving methods form a branch of _ geometrical numerical integration _ , a research topic whose main aim is preserving qualitative features of simulated differential equations . in this context , symplectic methods have had considerable attention due to their good long - time behavior as compared to standard methods for odes @xcite . a related interesting approach based upon. Please generate the next two sentences of the article

exponential / trigonometric fitting may be found in @xcite . unfortunately , symplecticity can not be fully combined with the energy preservation property @xcite , and this partly explains why the latter has been absent from the scene for a long time . among the first examples of energy - preserving methods we mention discrete gradient schemes @xcite which are defined by devising discrete analogs of the gradient function . the first formulae in this class had order at most two but recently discrete gradient methods of arbitrarily high order have been researched by considering the simpler case of systems with one - degree of freedom @xcite . here

Suppose that you have an abstract for a scientific paper: we study the thermodynamic casimir effect in thin films in the three dimensional xy universality class . to this end , we simulate the improved two component @xmath0 model on the simple cubic lattice . we use lattices up to the thickness @xmath1 . based on the results of our monte carlo simulations we compute the universal finite size scaling function @xmath2 that characterizes the behaviour of the thermodynamic casimir force in the neighbourhood of the critical point . we confirm that leading corrections to the universal finite size scaling behaviour due to free boundary conditions can be expressed by an effective thickness @xmath3 , with @xmath4 . our results are compared with experiments on films of @xmath5he near the @xmath6-transition , previous monte carlo simulations of the xy model on the simple cubic lattice and field - theoretic results . our result for the finite size scaling function @xmath2 is essentially consistent with the experiments on films of @xmath5he and the previous monte carlo simulations . 0.5 cm 0.5 cm * the thermodynamic casimir effect in the neighbourhood of the @xmath6-transition : + 0.2 cm a monte carlo study of an improved three dimensional lattice model * martin hasenbusch 0.3 cm _ institut fr physik , humboldt - universitt zu berlin _ _ newtonstr . 15 , 12489 berlin , germany _ _ e mail : martin.hasenbusch@physik.hu-berlin.de_ 0.4 cm * keywords : * @xmath6-transition , classical monte carlo simulation , thin films , thermodynamic casimir effect . And you have already written the first three sentences of the full article: in 1978 fisher and de gennes @xcite realized that there should be a so called `` thermodynamic '' casimir effect . this means that a force emerges when thermal fluctuations are restricted by a container . thermal fluctuations extend to large scales in the neighbourhood of critical points . in the thermodynamic limit ,. Please generate the next two sentences of the article

in the neighbourhood of the critical point , various quantities diverge following power laws . e.g. the correlation length , which measures the spatial extension of fluctuations , behaves as @xmath7 where @xmath8 is the reduced temperature and @xmath9 the critical temperature . @xmath10 and @xmath11 are the amplitude of the correlation length in the high and low temperature phase , respectively . while @xmath10 and @xmath11 depend on the microscopic details of the system , the critical exponent @xmath12 and the ratio @xmath13 are universal .

Suppose that you have an abstract for a scientific paper: construction of the japanese second - generation gravitational - wave detector kagra ( previously called lcgt ) has been started . in the next @xmath0 years , we will be able to observe the space - time ripple from faraway galaxies . kagra is equipped with the latest advanced technologies . the entire 3-km long detector is located in the underground to be isolated from the seismic motion , the core optics are cooled down to 20 k to reduce thermal fluctuations , and quantum non - demolition techniques are used to decrease quantum noise . in this paper , we introduce the detector configuration of kagra ; its design , strategy , and downselection of parameters . . And you have already written the first three sentences of the full article: kagra ( previously called lcgt for large - scale cryogenic gravitational - wave telescope ) is a japanese 3-km optical interferometer currently under construction in the kamioka mine . the aim of the detector is frequent observation of gravitational waves from faraway galaxies and to obtain unique information on the universe . the observation will be performed with other detectors in the us ( advanced ligo @xcite ) and europe ( advanced virgo @xcite and geo - hf @xcite ) , which are now being upgraded after several - year observations in the initial configurations .. Please generate the next two sentences of the article

kagra and the other three detectors are called second - generation gravitational - wave detectors . there are two unique features in the detector configuration of kagra .

Suppose that you have an abstract for a scientific paper: photosynthesis is the basic process used by plants to convert light energy in reaction centers into chemical energy . the high efficiency of this process is not yet understood today . using the formalism for the description of open quantum systems by means of a non - hermitian hamilton operator , we consider initially the interplay of gain ( acceptor ) and loss ( donor ) . near singular points it causes fluctuations of the cross section which appear without any excitation of internal degrees of freedom of the system . this process occurs therefore very quickly and with high efficiency . we then consider the excitation of resonance states of the system by means of these fluctuations . this second step of the whole process takes place much slower than the first one , because it involves the excitation of internal degrees of freedom of the system . the two - step process as a whole is highly efficient and the decay is bi - exponential . we provide , if possible , the results of analytical studies , otherwise characteristic numerical results . the similarities of the obtained results to light harvesting in photosynthetic organisms is discussed . . And you have already written the first three sentences of the full article: photosynthetic organisms capture visible light in their light - harvesting complex and transfer the excitation energy to the reaction center which stores the energy from the photon in chemical bonds . this process occurs with nearly perfect efficiency . although the primary process occurring in the light - harvesting complex , is the electron transfer between acceptor and donor , and the transfer to the reaction center appears as secondary process , the two processes should not be separated from one another .. Please generate the next two sentences of the article

both processes are nothing but two parts of the total light harvesting . a few years ago , evidence of coherent quantum energy transfer has been found experimentally @xcite .

Suppose that you have an abstract for a scientific paper: a higher dimensional lattice space can be decomposed into a number of four - dimensional lattices called as layers . the higher dimensional gauge theory on the lattice can be interpreted as four - dimensional gauge theories on the multi - layer with interactions between neighboring layers . we propose the new possibility to realize the continuum limit of a five - dimensional theory based on the property of the phase diagram . . And you have already written the first three sentences of the full article: in constructing a higher dimensional quantum field theory , the regularization and the continuum limit are two important keys . particularly , the problem of the limit associates with hard difficulty in the higher dimensional case . statistical mechanics usually insists that critical behaviors of the phase transition in the theory are equivalent to those of a mean field theory , which has only a trivial fixed point . many pioneering works on lattice gauge theories were trying to overcome the difficulty @xcite , although the continuum limit is not taken strictly . where is the continuum limit ? by using well - known 4-dimensional theories such as qed and qcd ,. Please generate the next two sentences of the article

is it possible to construct the continuum limit by the related critical behavior near the critical point ? our purpose is to construct a @xmath0-dimensional pure yang - mills theory by arranging a number of 4-dimensional yang - mills theories with appropriate couplings .

Suppose that you have an abstract for a scientific paper: we present an update of the one - meson - exchange ( ome ) results for the weak decay of s- and p - shell hypernuclei @xcite , paying special attention to the role played by final state interactions between the emitted nucleons . the present study also corrects for a mistake in the inclusion of the @xmath0 and @xmath1 exchange mechanisms , which substantially increases the ratio of neutron - induced to proton - induced transitions , @xmath2 . with the most up - to - date model ingredients , we find that the ome approach is able to describe very satisfactorily most of the measured observables , including the ratio @xmath2 . # 1#2@xmath3#2 pacs number(s ) : 21.80.+a , 24.80.+y , 13.30.eg , 13.75.ev , 13.75.cs . And you have already written the first three sentences of the full article: hypernuclei are bound systems of non - strange and strange baryons . in present facilities , hypernuclei are created with hadronic reactions as ( @xmath4,k ) at brookhaven and kek or electroproduction ones as ( e , ek ) at tjnaf. the decay of those objects proceeds via the weak interaction which is 10 orders of magnitude slower than the strong one and violates parity , isospin and strangeness . for the very light hypernuclei the mesonic decay mode ( @xmath5 ) is dominant , but as @xmath6 increases so does the pauli blocking acting on the outgoing nucleon , and hypernuclei mainly decay via the one - nucleon induced non - mesonic mode , @xmath7 . since the pioneering phenomenological model of block and dalitz @xcite. Please generate the next two sentences of the article

, many approaches have been developed to understand the dynamics of the decay , and the results have been collected in extensive review articles @xcite . many works are based on a meson exchange picture , either using a simple one - pion - exchange mechanism @xcite , or including also heavier meson exchanges , such as the @xmath8 @xcite or the complete pseudoscalar and vector meson octets @xcite .

Suppose that you have an abstract for a scientific paper: we report the first localization of diffuse , non - thermal , x - ray emission from a nearby galaxy cluster . using _ chandra _ data , we have isolated a diffuse non - thermal x - ray component with a photon index , @xmath0 = 2.21@xmath1 and a flux of 9.5@xmath2 photons @xmath3 s@xmath4 kev@xmath4 at 1 kev , that extends from @xmath51@xmath6.5 to @xmath52@xmath6.5 to the south of the x - ray flux peak . comparison to simulations implies that the diffuse non - thermal emission is produced by primary electrons , accelerated at shocks to relativistic velocities . using these results and the flux and hardness maps produced with data from the _ chandra _ advanced ccd imaging spectrometer , we conclude that a smaller subclump coming from the north merged with ic1262 . the offset of the cd galaxy from the x - ray peak and large peculiar velocity indicate that the subclump s impact parameter was to the west and on the near side of ic1262 . . And you have already written the first three sentences of the full article: recent _ chandra _ observations indicate that relativistic plasma injected into the intracluster medium ( icm ) from radio sources eventually detaches from the radio source , forming bubbles of radio plasma in the icm @xcite . in the model proposed by @xcite , these radio ghosts survive in the icm , and provide a seed population of cosmic rays(crs ) . diffuse non - thermal ( nt ) emission is produced when merger induced shocks re - accelerate , via the first order fermi process , this seed cr population .. Please generate the next two sentences of the article

current evidence suggests that these radio ghosts contain a significant population of protons as well as electrons @xcite . since @xcite demonstrated that diffuse nt x - ray emission could be produced by either primary electrons directly accelerated at shock fronts , or secondary electrons produced during proton - proton collisions , there are two possible sources for the observed diffuse nt emission . to determine the mechanism that produces diffuse nt emission requires accurate measurement of the spectrum and location of the nt emission .

Suppose that you have an abstract for a scientific paper: we investigate coupled circle maps in presence of feedback and explore various dynamical phases observed in this system of coupled high dimensional maps . we observe an interesting transition from localized chaos to spatiotemporal chaos . we study this transition as a dynamic phase transition . we observe that persistence acts as an excellent quantifier to describe this transition . taking the location of the fixed point of circle map ( which does not change with feedback ) as a reference point , we compute number of sites which have been greater than ( less than ) the fixed point till time @xmath0 . though local dynamics is high - dimensional in this case , this definition of persistence which tracks a single variable is an excellent quantifier for this transition . in most cases , we also obtain a well defined persistence exponent at the critical point and observe conventional scaling as seen in second order phase transitions . this indicates that persistence could work as good order parameter for transitions from fully or partially arrested phase . we also give an explanation of gaps in eigenvalue spectrum of the jacobian of localized state . _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _.... And you have already written the first three sentences of the full article: pattern formation in spatially extended systems has been an object of extensive study in past few decades . the reasons for the interest in pattern formation are not far to seek . pattern formation happens in several natural systems and scientists are interested in understanding it . examples could be flame propagation or occurrence of spirals in a chemical reactions or patterns on the skins of animals modeled by reaction - diffusion processes .. Please generate the next two sentences of the article

several systems like biological patterns @xcite , charge density waves or josephson junction arrays @xcite , lasers @xcite have been studied extensively from the viewpoint of dynamics and pattern formation . the practical importance of understanding above systems can not be overemphasized .

Suppose that you have an abstract for a scientific paper: we examine single chargino production in conjunction with r - parity lepton number violation in future lepton - lepton collisions . present bounds on r - parity violating couplings allow for a production cross section of the order of @xmath0 for a wide range of sneutrino and chargino masses . scenarios of chargino decay which lead to purely leptonic signals in the final state and without missing energy are also discussed . = 5000 = 5000 = 1000 @twoside -17pt eqnsel = mathrm#1#1ifundefinedmathrm#1#1 1.2 cm and . And you have already written the first three sentences of the full article: r - parity is a discrete symmetry defined by assigning to every field the number @xmath1 ( @xmath2 - baryon ( lepton ) number , @xmath3 - spin of the particle ) @xcite . if it is conserved then baryon and lepton number violating transitions are forbidden . in that case , the theory guarantees both proton stability and lepton universality . however , in supersymmetric extensions of the standard model , gauge invariance and renormalizability , the two main principles of any gauge theory , do not assure r - parity conservation . at present , wide phenomenological investigations of r - parity violating processes have been undertaken ( for reviews see e.g. @xcite ) . here. Please generate the next two sentences of the article

we will explore the possibility of discovering the lepton number violating process of single chargino production at future lepton - lepton colliders ( see fig.1(i ) for an electron - electron collision ) . to our knowledge this process has not yet been discussed , though lepton number violating charginos pair production in electron - electron collisions ( fig.1(ii ) ) has been considered @xcite .

Suppose that you have an abstract for a scientific paper: we show that standard next - to - leading order ( nlo ) perturbative qcd analyses used to extract @xmath0 from lep data do not serve to disentangle the completely unknown renormalization scheme ( rs ) invariant next - nlo ( nnlo ) and higher - order uncalculated corrections from those dependent on the renormalization scale in a predictable manner . the resulting quoted values of @xmath1 @xmath2 with attendant scheme dependence uncertainties therefore reflect the ad hoc way in which they were extracted , rather than the actual values of these parameters . choosing the scale so that the nlo coefficient vanishes ( effective charge scheme ) exposes the relative size of these unknown rs invariant higher order terms . they are seen to be sizeable for some of the lep observables , indicating that they must be estimated if @xmath3 is to be determined reliably . this can be accomplished either from nnlo calculations , at present only available for the hadronic width of the @xmath4 ( @xmath5 ) , or non - perturbatively by writing the rs - invariant uncertainty in @xmath6 in terms of the running @xmath7 of the observable r(q ) with energy using an effective charge formalism . the nnlo calculations for @xmath5 and lep data supplemented by lower energy petra data lead to @xmath8 mev . we also discuss how the effective charge approach can be used to remove scale dependence from next - to - leading logarithm resummations of some lep observables . = 11 addtoresetequationsection # 1 ( [ # 1 ] ) @=11 versim#1#20.2ex @=12 * measuring @xmath9 at lep * d.t . barclay _ department of physics , university of illinois _ _ at chicago , illinois 60680 , u.s.a _ c.j . maxwell and m.t . reader _ centre for particle theory , university of durham _ _ durham dh1 3le , england _ . And you have already written the first three sentences of the full article: the lep collaborations now all have high - statistics data samples which enable them to make accurate measurements of a wide range of @xmath10 qcd observables [ 1 - 9 ] - jet fractions , thrust distributions , the hadronic width of the @xmath4 , energy - energy correlations , etc .. for most of these quantities non - perturbative effects such as hadronization corrections are expected to be reasonably small and next - to - leading order ( nlo ) calculations are available in renormalization group ( rg ) improved qcd perturbation theory @xcite . for the hadronic width of the @xmath4 alone we have a next - nlo ( nnlo ) calculation available @xcite . by comparing such calculations with the data one hopes to be able to extract @xmath11 , the fundamental su(3 ) standard model parameter , or equivalently @xmath12 , the @xmath13 scheme coupling constant . unfortunately this intention is hampered by our rather limited current knowledge of what qcd actually predicts for any of these quantities due to the dependence of perturbative calculations at nlo on the unphysical renormalization scale @xmath14 , and more generally on the renormalization scheme ( rs ) in higher - orders . in a complete all - orders calculation of any quantity. Please generate the next two sentences of the article

the @xmath14-dependence would cancel and so it is an arbitary parameter , but our reliance on a truncated expansion in @xmath12 in which such a cancellation no longer quite occurs renders predictions ambiguous . since it was first clearly formulated in ref .

Suppose that you have an abstract for a scientific paper: using the qcd dipole picture of bfkl dynamics and the conformal invariance properties of the bfkl kernel in transverse coordinate space , we show that the @xmath0 dipole densities can be expressed in terms of dual shapiro - virasoro amplitudes @xmath1 and their generalization including non - zero conformal spins . we discuss the possibility of an effective closed string theory of interacting qcd dipoles . service de physique thorique cea - saclay f-91191 gif - sur - yvette france . And you have already written the first three sentences of the full article: the qcd `` hard pomeron '' is understood as the solution of perturbative qcd expansion at high energy ( @xmath2 ) after resumming the leading @xmath3 terms . it is known to obey the bfkl equation@xcite . it has recently attracted a lot of interest in relation with the experimental results obtained at hera for deep - inelastic scattering reactions at very low value of @xmath4 where @xmath5 is the virtuality of the photon probe @xmath6 and @xmath2 is , in this case , the c.o.m energy of the @xmath6-proton system .. Please generate the next two sentences of the article

interestingly enough , the proton structure functions increase with @xmath2 at fixed @xmath7@xcite in a way qualitatively compatible with the prediction of the bfkl equation . however , the phenomenological discussion is still under way , since scattering of a `` hard '' probe on a proton is not a fully perturbative qcd process and moreover , alternative explanations based on renormalization group evolution equations do exist@xcite . on the other hand ,

Suppose that you have an abstract for a scientific paper: the general properties of the non - thermal non - pulsed x - ray emission of rotation powered pulsars are investigated in the context of a pulsar wind nebula model . an examination of the observed x - ray emission from a sample of 23 pulsars in the energy range between 2 - 10 kev reveals that the relation of x - ray luminosity , @xmath0 , to the pulsar spin down power , @xmath1 , is steeper for the non - pulsed component than for the pulsed component . specifically , @xmath2 for the non - pulsed component , whereas @xmath3 for the pulsed component . the former relation is consistent with emission from a pulsar wind nebula model in which @xmath4 where @xmath5 is the power law index of the electron energy distribution . the relation for the pulsed component , on the other hand , is consistent with a magnetospheric emission model . in addition , the photon spectral index , @xmath6 , was found to be correlated to the conversion efficiency of spin down power to non - pulsed x - ray emission with greater efficiencies for @xmath7 than for @xmath8 . such a relation is naturally understood within the framework of a pulsar wind nebula model with the former relation corresponding to the emission of x - rays in the fast cooling regime and the latter relation corresponding to emission in the slow cooling regime . the x - ray properties of pulsar wind nebulae are sensitive to the physical conditions ( e.g. , the density and magnetic field ) of the interstellar medium and can lead to important differences between the x - ray emission characteristics ( luminosity , photon spectral index and emission morphology ) of pulsars in various environments . such wind nebulae can contribute to the non - thermal symmetric emission morphology ( point - like ) and elongated emission morphology ( tail - like ) from sources similar to geminga and psr b1757 - 24 . # 1 # 1#2#1 # 2 . And you have already written the first three sentences of the full article: the study of the emission characteristics from rotation powered pulsars has been a subject of long standing interest . our knowledge of the fundamental properties ( e.g. , mass , spin , and magnetic field ) of the underlying neutron star stems from detailed spectral and timing investigations . to facilitate an understanding of the mechanism by which the loss of rotational energy is converted into high energy radiation , many observational and theoretical studies have sought to determine the relationship between the x - ray luminosity , @xmath0 , and the rate of rotational energy loss or spin down power , @xmath1 .. Please generate the next two sentences of the article

indeed , a correlation of the form @xmath9 was found in einstein data by seward & wang ( 1988 ) . subsequent studies using a larger sample of pulsars led to a relation of the form , @xmath10 based on rosat data ( see becker & trmper 1997 ) and @xmath11 based on asca data ( see saito 1998 ) .

Suppose that you have an abstract for a scientific paper: in this paper we examine robust clustering behaviour with multiple nontrivial clusters for identically and globally coupled phase oscillators . these systems are such that the dynamics is completely determined by the number of oscillators @xmath0 and a single scalar function @xmath1 ( the coupling function ) . previous work has shown that ( a ) any clustering can stably appear via choice of a suitable coupling function and ( b ) open sets of coupling functions can generate heteroclinic network attractors between cluster states of saddle type , though there seem to be no examples where saddles with more than two nontrivial clusters are involved . in this work we clarify the relationship between the coupling function and the dynamics . we focus on cases where the clusters are inequivalent in the sense of not being related by a temporal symmetry , and demonstrate that there are coupling functions that give robust heteroclinic networks between periodic states involving three or more nontrivial clusters . we consider an example for @xmath2 oscillators where the clustering is into three inequivalent clusters . we also discuss some aspects of the bifurcation structure for periodic multi - cluster states and show that the transverse stability of inequivalent clusters can , to a large extent , be varied independently of the tangential stability . . And you have already written the first three sentences of the full article: coupled oscillator models exhibit complex dynamics that has been observed in a wide range of different fields including physical @xcite and biological @xcite models . synchronization @xcite , clustering @xcite , chaos @xcite and spontaneous switching between different cluster states @xcite have all been observed in such systems . other studies have examined coupling between two or more systems that may individually be chaotic , and a wide variety of types of synchronization have been found and analysed ; see for example @xcite .. Please generate the next two sentences of the article

we examine phase oscillator models that are appropriate if the coupling between oscillators is weak compared to the attraction onto the limit cycle ( e.g. @xcite ) . although the coupling structure and strength are important for the dynamical behaviour of the system , the exact coupling function ( which represents the nonlinearities in the oscillators and the coupling ) has a subtle effect on the collective behaviour of the system .

Suppose that you have an abstract for a scientific paper: we quantitatively examine the extent to which instanton degress of freedom , contained within standard monte - carlo generated gauge - field configurations , can maintain the characteristic features of the mass and renormalisation functions of the non - perturbative quark propagator . we use over - improved stout - link smearing to isolate instanton effects on the lattice . using a variety of measures , we illustrate how gauge fields consisting almost solely of instanton - like objects are produced after only 50 sweeps of smearing . we find a full vacuum , with a packing fraction more than three times larger than phenomenological models predict . we calculate the overlap quark propagator on these smeared configurations , and find that even at high levels of smearing the majority of the characteristic features of the propagator are reproduced . we thus conclude that instantons contained within standard monte - carlo generated gauge - field configurations are the degrees of freedom responsible for the dynamical generation of mass observed in lattice qcd . . And you have already written the first three sentences of the full article: instantons are believed to be an essential component of the long - distance physics of the qcd vacuum , and the lattice provides a unique opportunity to gain insight into their role . in this study , we will for the first time quantitatively examine the extent to which instanton degrees of freedom , contained within standard monte - carlo generated gauge - field configurations , can maintain the characteristic features of the mass and renormalisation functions of the non - perturbative quark propagator . in order to isolate the effects of instanton degrees of freedom a uv filter is required to remove topologically non - trivial fluctuations . a variety of filters have been used , including cooling@xcite , ape smearing@xcite , hyp smearing @xcite and stout link smearing @xcite , among others .. Please generate the next two sentences of the article

these algorithms can suffer from destruction of the instanton content of the vacuum , and so in this work we use over - improved stout - link smearing @xcite , a form of smearing tuned to preserve instantons . section [ sec : smearing ] briefly describes these smearing methods .

Suppose that you have an abstract for a scientific paper: this paper introduces a homology theory for links in i - bundles over an orientable surface . the theory is unique in that the elements of the chain groups are surfaces instead of diagrams . it is then shown this theory yields the same results as the homology theory constructed by asaeda , przytycki and sikora . . And you have already written the first three sentences of the full article: in [ k ] khovanov introduced a homology theory for links in @xmath0 that was a categorification of the jones polynomial . in [ aps ] asaeda , przytycki and sikora extended this theory to links embedded in i - bundles . their homology theory incorporated some of the topology of the i - bundle into their invariant . turner and turaev showed in [ t ] that the homology from [ aps ] could be recreated using embedded surfaces as elements of the chain groups instead of decorated diagrams . in this paper. Please generate the next two sentences of the article

we accomplish that in the case of i - bundles over orientable surfaces . section 2 contains definitions and explains the skein relations on surfaces that are used .

Suppose that you have an abstract for a scientific paper: let @xmath0 be a finite set of points in general position in the plane . the structure of the complete graph @xmath1 as a geometric graph includes , for any pair @xmath2,[c , d]$ ] of vertex - disjoint edges , the information whether they cross or not . the simple ( i.e. , non - crossing ) spanning trees ( ssts ) of @xmath1 are the vertices of the so - called geometric tree graph of @xmath0 , @xmath3 . two such vertices are adjacent in @xmath3 if they differ in exactly two edges , i.e. , if one can be obtained from the other by deleting an edge and adding another edge . in this paper we show how to reconstruct from @xmath3 ( regarded as an abstract graph ) the structure of @xmath1 as a geometric graph . we first identify within @xmath3 the vertices that correspond to spanning stars . then we regard each star @xmath4 with center @xmath5 as the representative in @xmath3 of the vertex @xmath5 of @xmath1 . ( this correspondence is determined only up to an automorphism of @xmath1 as a geometric graph . ) finally we determine for any four distinct stars @xmath6 and @xmath7 , by looking at their relative positions in @xmath3 , whether the corresponding segments cross . . And you have already written the first three sentences of the full article: graph reconstruction is an old and extensive research topic . it dates back to the _ reconstruction conjecture _ raised by kelly and ulam in 1941 ( see @xcite ) , which asserts that every graph on at least three vertices is uniquely determined by its collection of vertex deleted subgraphs . as a natural extension of the reconstruction conjecture , numerous papers considered either reconstruction of structures other then graphs ( a research topic proposed by ulam in 1960 ) , or reconstructions of graphs from other information . in the first direction , reconstructed objects include colored graphs , hypergraphs , matroids , relations , and other classes . in the second direction ,. Please generate the next two sentences of the article

the `` information '' may be @xmath8-vertex deleted subgraphs , edge - deleted subgraphs , elementary contractions , spanning trees , etc . in addition , various papers considered reconstruction of _ parameters of the graph _ instead of its full structure . such parameters include the order , the degree sequence , planarity , the types of spanning trees , and many others ( see the surveys @xcite for references ) . in this paper , we study the problem of reconstructing the geometric structure of a set of points in the plane from its geometric tree graph . _

Suppose that you have an abstract for a scientific paper: the three - band model relevant to high temperature copper - oxide superconductors is solved using single - site dynamical mean field theory and a tight - binding parametrization of the copper and oxygen bands . for a band filling of one hole per unit cell the metal / charge - transfer - insulator phase diagram is determined . the electron spectral function , optical conductivity and quasiparticle mass enhancement are computed as functions of electron and hole doping for parameters such that the corresponding to the paramagnetic metal and charge - transfer insulator sides of the one hole per cell phase diagram . the optical conductivity is computed using the peierls phase approximation for the optical matrix elements . the calculation includes the physics of `` zhang - rice singlets '' . the effects of antiferromagnetism on the magnitude of the gap and the relation between correlation strength and doping - induced changes in state density are determined . three band and one band models are compared . the two models are found to yield quantitatively consistent results for all energies less than about @xmath0ev , including energies in the vicinity of the charge - transfer gap . parameters on the insulating side of the metal / charge - transfer insulator phase boundary lead to gaps which are too large and near - gap conductivities which are too small relative to data . the results place the cuprates clearly in the intermediate correlation regime , on the paramagnetic metal side of the metal / charge - transfer insulator phase boundary . . And you have already written the first three sentences of the full article: the interplay of band theoretic issues of hybridization and chemical bonding with the quantum chemical issue of strong local correlations is basic to the physics of many important materials . in an important paper @xcite zaanen , sawatzky and allen classified insulating transition metal oxides as `` charge - transfer '' or `` mott '' insulators according to whether the physics could be discussed solely in terms of strong correlated transition metal @xmath1 states or whether transitions to o @xmath2 states were important to the low energy physics . the issue arises with particular force in the high temperature superconductors where the cu @xmath3 and @xmath4 states are not far in energy from o @xmath2 states , but the cu @xmath5 state is very far away in energy . in this circumstance. Please generate the next two sentences of the article

a strong particle - hole asymmetry is expected @xcite , with doped electrons residing on cu sites whereas doped holes reside mainly on the o , but may be bound to cu spins creating zhang - rice singlets".@xcite quantifying this appealing physical picture requires solving an electronic structure problem with multiple scales , including a correlation energy on the cu site @xmath6ev , a cu - o energy level difference of 2 - 4ev,@xcite and a cu - o hybridization @xmath7ev.@xcite in this paper we use single - site dynamical mean - field theory ( dmft ) to solve a model involving both copper and oxygen orbitals , developing a comprehensive theoretical picture of the electronic structure and optical conductivity of undoped and doped cuprate materials across the charge - transfer - insulator to charge - transfer metal phase diagram , including the effect of antiferromagnetism on the spectra and optics .

Suppose that you have an abstract for a scientific paper: a starquake mechanism for pulsar glitches is developed in the solid quark star model . it is found that the general glitch natures ( i.e. , the glitch amplitudes and the time intervals ) could be reproduced if solid quark matter , with high baryon density but low temperature , has properties of shear modulus @xmath0 erg/@xmath1 and critical stress @xmath2 erg/@xmath1 . the post - glitch behavior may represent a kind of damped oscillations . _ pacs codes : _ 97.60.g , 97.60.j , 11.80.f , , , , pulsars , neutron stars , elementary particles . And you have already written the first three sentences of the full article: pulsars are unique objects , with which all types of elemental interaction could be tested extremely . however , the most elementary question relevant is still open : _ what is the nature of pulsars ? _ it is conventionally thought that pulsars are simply a kind of boring big `` nuclei '' neutron stars , but more and more attention is paid to the quark star model for pulsars @xcite since _ no _ convincing work , neither in theory from first principles nor in observation , has confirmed baade - zwicky s original idea that supernovae produce neutron stars . the bare quark surface is suggested to be a new probe for identifying quark stars with strangeness , and possible observational evidence for bare strange stars appears : the drifting subpulses of radio pulsars , ultra - high luminosity of soft @xmath3-ray repeaters , non - atomic thermal spectra of isolated `` neutron '' stars @xcite . however , can the bare strange star model reproduce most of the general features of pulsars ( especially glitches ) ? the observation of free precession in psr b1828 - 11 @xcite and psr b1642 - 03 @xcite challenges astrophysicists today to re - consider the internal structure of radio pulsars @xcite . the current model for glitches involves neutron superfluid vertex pinning and the consequent fluid dynamics. Please generate the next two sentences of the article

. however , the pinning should be much weaker than predicted in the glitch models , otherwise the vortex pinning will damp out the precession on timescales being much smaller than observed . in addition the picture , that a neutron star core containing coexisting neutron vertices and proton flux tubes , is also inconsistent with observations of freely precessing pulsars @xcite .

Suppose that you have an abstract for a scientific paper: we present a sensitive diffusion cloud chamber which does not require any radioactive sources . a major difference from a commonly used chamber is use of a heat sink as its bottom plate . a result of a performance test of the chamber is given . . And you have already written the first three sentences of the full article: in most countries , learning microscopic origin of nature is considered to be an important topic in science education . however , there are not so many student experiments or demonstrations which exhibit the existence of individual atom in direct and intuitive manner . the cloud chamber experiment is a rare exception ; it provides most direct and intuitive way to convince students existence of microscopic particles . beautiful tracks of particles draw audience s attention and interest .. Please generate the next two sentences of the article

various chambers have been developed and used in classroom @xcite . most of simple chambers seem to be based on the results of needles and nielsen @xcite and cowan @xcite , which use a block of dry ice and a beaker filled with ethanol vapour .

Suppose that you have an abstract for a scientific paper: compressive sensing is considered a huge breakthrough in signal acquisition . it allows recording an image consisting of @xmath0 pixels using much fewer than @xmath0 measurements if it can be transformed to a basis where most pixels take on negligibly small values . standard compressive sensing techniques suffer from the computational overhead needed to reconstruct an image with typical computation times between hours and days and are thus not optimal for applications in physics and spectroscopy . we demonstrate an adaptive compressive sampling technique that performs measurements directly in a sparse basis . it needs much fewer than @xmath0 measurements without any computational overhead , so the result is available instantly . computational ghost imaging ( cgi ) is a novel imaging technique that has received significant attention during the last few years@xcite . it is a consequent further development of conventional ghost imaging @xcite which allows to record spatially resolved images using a detector without spatial resolution . in conventional ghost imaging the image is recorded using two spatially correlated light beams , one object and one reference beam . the object beam illuminates the object to be imaged and is then collected using a bucket detector . the reference beam never interacts with the object and is recorded using a pixelated device offering spatial resolution . as both beams are spatially correlated the coincidence count signal allows one to retrieve a ghost image of the object . ghost imaging using both entangled photons @xcite or classical light @xcite as the spatially correlated twin beam source has been demonstrated . a seminal paper by shapiro @xcite clarified that the sole purpose of the reference beam lies in determining the illumination pattern at the object position at each instant , while the object beam gives data about the transmission of this pattern through the object . therefore , if one can create a deterministic illumination pattern at the.... And you have already written the first three sentences of the full article: we demonstrate an alternative way to perform compressive cgi ( ccgi ) without any computational overhead once all measurements have been performed by using an adaptive measurement scheme . we follow a promising strategy for adaptive compressive sensing that suggests replacing the random speckle patterns by directly using the patterns that form the sparse basis @xcite . we start the discussion of our strategy by recalling the properties of the 2d haar wavelet transform of square images consisting of @xmath2 pixels .. Please generate the next two sentences of the article

the wavelet decomposition procedure is schematically depicted in figure [ monkey ] . the decomposition of the image @xmath3 is performed seperately for rows and columns . at first each row is divided into @xmath4 pairs of adjacent pixels .

Suppose that you have an abstract for a scientific paper: we consider the dynamics towards the initial singularity of bianchi type ix vacuum and orthogonal perfect fluid models with a linear equation of state . surprisingly few facts are known about the ` mixmaster ' dynamics of these models , while at the same time most of the commonly held beliefs are rather vague . in this paper , we use mixmaster facts as a base to build an infrastructure that makes it possible to sharpen the main mixmaster beliefs . we formulate explicit conjectures concerning ( i ) the past asymptotic states of type ix solutions and ( ii ) the relevance of the mixmaster / kasner map for generic past asymptotic dynamics . the evidence for the conjectures is based on a study of the stochastic properties of this map in conjunction with dynamical systems techniques . we use a dynamical systems formulation , since this approach has so far been the only successful path to obtain theorems , but we also make comparisons with the ` metric ' and hamiltonian ` billiard ' approaches . . And you have already written the first three sentences of the full article: today , bianchi type ix enjoys an almost mythical status in general relativity and cosmology , which is due to two commonly held beliefs : ( i ) type ix dynamics is believed to be essentially understood ; ( ii ) bianchi type ix is believed to be a role model that captures the generic features of generic spacelike singularities . however , we will illustrate in this paper that there are reasons to question these beliefs . the idea that type ix is essentially understood is a misconception .. Please generate the next two sentences of the article

in actuality , surprisingly little is known , i.e. , proved , about type ix asymptotic dynamics ; at the same time there exist widely held , but rather vague , beliefs about mixmaster dynamics , oscillations , and chaos , which are frequently mistaken to be facts . there is thus a need for clarification : what are the known facts and what is merely believed about type ix asymptotics ? we will address this issue in two ways : on the one hand , we will discuss the main rigorous results on mixmaster dynamics , the ` bianchi type ix attractor theorem ' , and its consequences ; in particular , we will point out the limitations of these results . on the other hand

Suppose that you have an abstract for a scientific paper: recent studies of core - collapse supernovae have revealed the existence of two distinct classes of massive supernovae ( sne ) : 1 ) very energetic sne ( hypernovae ) , whose kinetic energy ( ke ) exceeds @xmath0erg , about 10 times the ke of normal core - collapse sne , and 2 ) very faint and low energy sne ( @xmath1 0.5 @xmath2 @xmath3erg ; faint supernovae ) . these two classes of supernovae are likely to be `` black - hole - forming '' supernovae with rotating or non - rotating black holes . we compare their nucleosynthesis yields with the abundances of extremely metal - poor ( emp ) stars to identify the pop iii ( or first ) supernovae . we show that the emp stars , especially the c - rich type , are likely to be enriched by black - hole - forming supernovae . . And you have already written the first three sentences of the full article: stars more massive than @xmath4 25 @xmath5 form a black hole at the end of their evolution . stars with non - rotating black holes are likely to collapse `` quietly '' ejecting a small amount of heavy elements ( faint supernovae ) . in contrast , stars with rotating black holes are likely to give rise to very energetic supernovae ( hypernovae ) . we present distinct nucleosynthesis features of these two classes of `` black - hole - forming '' supernovae .. Please generate the next two sentences of the article

nucleosynthesis in hypernovae is characterized by larger abundance ratios ( zn , co , v , ti)/fe and smaller ( mn , cr)/fe than normal supernovae , which can explain the observed trend of these ratios in extremely metal - poor stars . nucleosynthesis in faint supernovae is characterized by a large amount of fall - back .

Suppose that you have an abstract for a scientific paper: we consider harmonics generation and wave - mixing by two - color multiphoton resonant excitation of three - level atoms / molecules in strong laser fields . the coherent part of the spectra corresponding to multicolor harmonics generation is investigated . the obtained analytical results on the basis of generalized rotating wave approximation are in a good agreement with numerical calculations . the results applied to the hydrogen atom and homonuclear diatomic molecular ion show that one can achieve efficient generation of moderately high multicolor harmonics via multiphoton resonant excitation by appropriate laser pulses . . And you have already written the first three sentences of the full article: harmonics generation and wave - mixing are one of the basic phenomena of nonlinear optics which have been extensively studied both theoretically and experimentally with the advent of lasers @xcite . recent advance in laser technologies has provided ultrahigh intensities for supershort laser pulses that makes achievable non - perturbative regime of harmonic generation , which significantly extends the spectral region accessible by lasers , in particular , for short wavelengths towards vuv / xuv or even x - ray radiation @xcite . such short wavelength radiation is of great interest due to numerous significant applications , e.g. in quantum control , spectroscopy , sensing and imaging etc .. depending on the laser - atom interaction parameters , harmonic generation may arise from bound - bound @xcite and bound - free - bound transitions via continuum spectrum @xcite .. Please generate the next two sentences of the article

bound - bound mechanism of harmonic generation without ionization is more efficient for generation of moderately high harmonics @xcite . for this mechanism resonant interaction is of importance .

Suppose that you have an abstract for a scientific paper: in this paper we construct approximations for the caputo derivative of order @xmath0 and @xmath1 . the approximations have weights @xmath2 and @xmath3 , and the higher accuracy is achieved by modifying the initial and last weights using the expansion formulas for the left and right endpoints . the approximations are applied for computing the numerical solution of ordinary fractional differential equations . the properties of the weights of the approximations of order @xmath4 are similar to the properties of the @xmath5 approximation . in all experiments presented in the paper the accuracy of the numerical solutions using the approximation of order @xmath4 which has weights @xmath3 is higher than the accuracy of the numerical solutions using the @xmath5 approximation for the caputo derivative . * 2010 math subject classification : * 26a33 , 34a08 , 34e05 , 41a25 + * key words and phrases : * fractional derivative , approximation , fourier transform , fractional differential equation . . And you have already written the first three sentences of the full article: the grnwald formula approximation and the @xmath5 approximation of the caputo derivative have been regularly used for numerical solution of fractional differential equations @xcite . the grnwald formula approximation has weights @xmath6 and accuracy @xmath7 . the @xmath5 approximation has order @xmath4 and weights @xmath8 .. Please generate the next two sentences of the article

the weights of the @xmath5 approximation are linear combinations of terms which have power @xmath9 . in the present paper we construct approximations of the caputo derivative whose weights consist of terms which have power @xmath10 and @xmath11 .

Suppose that you have an abstract for a scientific paper: we report a detection of statistically significant color variations for a sample of 7,531 multiply observed asteroids that are listed in the sloan digital sky survey moving object catalog . using 5-band photometric observations accurate to @xmath00.02 mag , we detect color variations in the range 0.06 - 0.11 mag ( rms ) . these variations appear uncorrelated with asteroids physical characteristics such as diameter ( in the probed 1 - 10 km range ) , taxonomic class , and family membership . despite such a lack of correlation , which implies a random nature for the cause of color variability , a suite of tests suggest that the detected variations are not instrumental effects . in particular , the observed color variations are incompatible with photometric errors , and , for objects observed at least four times , the color change in the first pair of observations is correlated with the color change in the second pair . these facts strongly suggest that the observed effect is real , and also indicate that for some asteroids color variations are larger than for others . the detected color variations can be explained as due to inhomogeneous albedo distribution over an asteroid surface . although relatively small , these variations suggest that fairly large patches with different color than their surroundings exist on a significant fraction of asteroids . this conclusion is in agreement with spatially resolved color images of several large asteroids obtained by near spacecraft and hst . . And you have already written the first three sentences of the full article: asteroids are rotating aspherical reflective bodies which thus exhibit brightness variations . as recognized long ago ( russell 1906 , metcalf 1907 ) , studies of their lightcurves provide important constraints on their physical properties , and processes that affect their evolution . for example , well - sampled and accurate lightcurves can be used to determine asteroid asphericity , spin vector , and even the albedo inhomogeneity across the surface ( magnusson 1991 ) . the current knowledge about asteroid rotation rates and lightcurve properties is well summarized by pravec & harris ( 2000 ) . the rotational periods range from @xmath02 hours to @xmath0 15 hours .. Please generate the next two sentences of the article

the lightcurve amplitudes for main - belt asteroids and near - earth objects are typically of the order 0.1 - 0.2 mag . ( peak - to - peak ) .

Suppose that you have an abstract for a scientific paper: we propose a new parametrization of the distribution of the initial eccentricity in a nucleus - nucleus collision at a fixed centrality , which we name the elliptic power distribution . it is a two - parameter distribution , where one of the parameters corresponds to the intrinsic eccentricity , while the other parameter controls the magnitude of eccentricity fluctuations . unlike the previously used bessel - gaussian distribution , which becomes worse for more peripheral collisions , the new elliptic power distribution fits several monte carlo models of the initial state for all centralities . . And you have already written the first three sentences of the full article: elliptic flow , @xmath0 , is a crucial observable of heavy - ion collisions : the large magnitude of @xmath0 at rhic @xcite and lhc @xcite provides the strongest evidence that a low - viscosity fluid is formed in these collisions @xcite . elliptic flow is determined to a good approximation by linear response to the initial eccentricity @xmath1 , which quantifies the spatial azimuthal anisotropy of the fireball created right after the collision @xcite . this initial eccentricity comes from two effects : first , the overlap area between the colliding nuclei has the shape of an almond in non - central collisions , where the smaller dimension of the almond is parallel to the reaction plane .. Please generate the next two sentences of the article

this results in an eccentricity which becomes larger as impact parameter increases , and whose magnitude is model dependent @xcite . second , even in central collisions , there is a sizable eccentricity due to quantum fluctuations in wave functions of incoming nuclei @xcite , and to the probabilistic nature of energy deposition in nucleon - nucleon collisions .

Suppose that you have an abstract for a scientific paper: qcdoc is a massively parallel supercomputer whose processing nodes are based on an application - specific integrated circuit ( asic ) . this asic was custom - designed so that crucial lattice qcd kernels achieve an overall sustained performance of 50% on machines with several 10,000 nodes . this strong scalability , together with low power consumption and a price / performance ratio of $ 1 per sustained mflops , enable qcdoc to attack the most demanding lattice qcd problems . the first asics became available in june of 2003 , and the testing performed so far has shown all systems functioning according to specification . we review the hardware and software status of qcdoc and present performance figures obtained in real hardware as well as in simulation . . And you have already written the first three sentences of the full article: continued advances in commodity processing and networking hardware make pc ( or workstation ) clusters a very attractive alternative for lattice qcd calculations @xcite . indeed , there are quite a few important problems that can be addressed on pc clusters , and many lattice physicists are taking advantage of this opportunity . however , for the most demanding problems in lattice qcd , e.g. dynamical fermion simulations with realistic quark masses , one would like to distribute the global volume over as many nodes as possible , resulting in a very small local volume per node . pc clusters are inadequate to deal with this case because the communications latency inherent in their networking hardware implies that the local volume must not be chosen too small if a reasonable sustained performance is to be achieved . in other words , for typical lattice qcd problems. Please generate the next two sentences of the article

pc clusters do not scale well beyond a few hundred nodes . in custom - designed supercomputers such as qcdoc @xcite and apenext @xcite , the communications hardware is designed to reduce the latencies and to assist critical operations ( such as global sums ) in hardware . as a result , these machines are significantly more scalable and allow for much smaller local volumes .

Suppose that you have an abstract for a scientific paper: we present here a powerful method providing simultaneous atomic spatial and nanosecond temporal resolution for investigating dynamics and structure on the atomic scale , in general . we reveal the dynamic reorganization of surface ( ad)atoms induced by radio frequency alternating charging and decharging of a metal . our method utilizes taylor - made nano - fabricated two - dimensional islands of physisorbed argon atoms , acting as motion sensors , probed by a radio frequency low - temperature scanning tunneling microscope . charge oscillations forced by voltages and currents alternating at radio frequency ( rf ) play a dominant role in practically all electronic devices used in our daily life . such charge oscillations are known to excite plasmons in the quasi - two - dimensional skin layer at the surface of metals @xcite . in addition , due to electrostriction @xcite , a periodically modulated electric ( @xmath0 ) field gives rise to forced small - amplitude mechanical oscillations of the atomic lattice , @xmath0-fields of @xmath1v / m typically generating strain of 0.1 % @xcite . such mechanical oscillations are utilized as surface acoustic waves in piezoelectric biosensors @xcite and frequency filters for telecommunication @xcite ; they enable the tuning of electronic and magnetic properties of materials @xcite as well as the operation of artificial muscles for robots and artificial limbs @xcite ; ultrasonic irradiation facilitates to control spin lattice relaxation times and peak widths in nuclear magnetic resonance @xcite . for measuring strain , macroscopic techniques such as x - ray diffraction @xcite or cantilever beam techniques @xcite are well established . detection of picometer - scale mechanical amplitudes of the surface atomic lattice has been achieved up to 1ghz by an rf - modified scanning tunneling microscope @xcite . near - field microwave microscopy has demonstrated the electrodynamical response of the material on length scales far shorter than the free - space.... And you have already written the first three sentences of the full article: the experiments were performed in ultrahigh vacuum ( base pressure : @xmath42 mbar ) with a radio - frequency low - temperature scanning tunneling microscope @xcite operated at 5k . it utilizes a sharp tungsten tip ( electrochemically etched and thermally deoxidized above 1070k ) as , both , imaging probe as well as movable ground - electrode against the flat sample . the latter is a ag(111 ) single - crystal prepared by repeated cycles of ar@xmath43 ion sputtering ( 600ev ) and thermal annealing at 720k .. Please generate the next two sentences of the article

the ag(111 ) sample is biased from independent rf- and dc - voltage sources for applying ac and dc @xmath0-fields of @xmath44@xmath45v / m at its surface . the rf - circuit and electronics are described elsewhere @xcite .

Suppose that you have an abstract for a scientific paper: high - resolution _ hubble space telescope ( hst ) _ imaging observations of star cluster systems provide a very interesting and useful alternative for stellar population analyses to spectroscopic studies with 8m - class telescopes . here , we assess the systematic uncertainties in ( young ) cluster age , mass , and to a lesser extent extinction and metallicity determinations , based on broad - band imaging observations with the _ hst_. our aim here is to intercompare the results obtained using a variety of commonly used modelling techniques , specifically with respect to our own extensively tested multi - dimensional approach . any significant differences among the resulting parameters are due to the details of the various , independently developed modelling techniques used , rather than to the stellar population models themselves . despite the model uncertainties and the selection effects inherent to most methods used , we find that the _ peaks _ in the relative age and mass distributions of a given young ( @xmath0 yr ) cluster system can be derived relatively robustly and consistently , to accuracies of @xmath1 and @xmath2 , respectively , assuming gaussian distributions in cluster ages and masses for reasons of simplicity . the peaks in the relative mass distributions can be obtained with a higher degree of confidence than those in the relative age distributions , as exemplified by the smaller spread among the peak values of the mass distributions derived . this implies that mass determinations are mostly insensitive to the approach adopted . we reiterate that as extensive a wavelength coverage as possible is required to obtain robust and internally consistent age and mass estimates for the individual objects , with reasonable uncertainties . finally , we conclude that the _ actual _ filter systems used for the observations should be used for constructing model colours , instead of using conversion equations , to achieve more accurate derivations of ages and masses . methods : data.... And you have already written the first three sentences of the full article: the _ systematic _ uncertainties in the determination of the ages , masses , and to a lesser extent extinction and metallicity of young extragalactic star clusters , based on broad - band imaging observations , but using a variety of analysis approaches are poorly understood . our aim in this paper is to intercompare the results obtained from _ hubble space telescope ( hst ) _ observations of carefully selected young star cluster samples using a variety of commonly used modelling techniques , and characterise the major differences among the techniques . we will do this specifically with respect to our own extensively tested multi - dimensional approach , which we will use as our main benchmark . at one time or another during its lifetime. Please generate the next two sentences of the article

, every galaxy will be affected by the external gravitational effects , however minor , exerted by its neighbour galaxies . irrespective of the precise interaction geometry , the results of such interactions are often striking : depending on the available gas reservoir , violent star formation will ensue , frequently predominantly in the guise of active star _ cluster

Suppose that you have an abstract for a scientific paper: the spatial power spectrum of the hi 21 cm intensity in the small magellanic cloud ( stanimirovic 1999 ) is a power law over scales as large as those of the smc itself . it was interpreted as due to turbulence by goldman ( 2000 ) and by stanimirovic & lazarian ( 2001 ) . the question is whether the power spectrum is indeed the result of a dynamical turbulence or is merely the result of a structured static density . in the turbulence interpretation of goldman ( 2000 ) the turbulence was generated by the tidal effects of the last close passage of the lmc about 0.2 gyr ago . the turbulence time - scale was estimated by goldman to be 0.4 gyr , so the turbulence has not decayed yet . staveley - smith ( 1997 ) observed in the smc about five hundreds of hi super shells . their age is more than an order of magnitude smaller than the turbulence age . therefore , if the turbulence explanation holds , their observed radial velocities should reflect the turbulence in the gas in which they formed . in the present work we analyze the observed radial velocities of the super shells . we find that the velocities indeed manifest the statistical spatial correlations expected from turbulence . the turbulence spectrum is consistent with that obtained by goldman(2000 ) . . And you have already written the first three sentences of the full article: the spatial power spectrum of the hi 21 cm intensity in the small magellanic cloud was obtained by stanimirovic ( 1999 ) . interestingly , it is a power law over scales as large as that of the smc itself . similar power laws have been observed by crovisier & dickey ( 1983 ) and by green ( 1993 ) in the galaxy .. Please generate the next two sentences of the article

the outstanding feature in the case of the smc is the large scale of the observed correlations . the power laws signal underlying long range correlations in what looks like a field of random fluctuations of the intensity . for an optically thin medium along the line of sight , the 21 cm intensity is proportional to the column density

Suppose that you have an abstract for a scientific paper: @xcite suggested an empirical relation between the magnetic field strength along the line of sight ( los ) and the dispersion of faraday rotation measure ( rm ) distribution in turbulent media with root - mean - square sonic mach number @xmath0 . in this paper , we extend the work by incorporating the mach number dependence . media with @xmath1 are considered to cover the mach number range of the warm ionized medium ( wim ) of our galaxy . three - dimensional , magnetohydrodynamic isothermal turbulence simulations with solenoidal forcing are used . we suggest a new relation among the los magnetic field strength , the dispersion of rm distribution , and the mach number , which approximately represents the relation for alfvnic perturbations . in addition , we suggest a relation between the mach number and the dispersion of log - normal distribution of emission measure ( em ) , which is basically the relation for the mach number and the density dispersion . the relations could be used for a quick and rough estimation of the los magnetic field strength in the turbulent wim . ism : magnetic fields - methods : numerical - mhd - turbulence . And you have already written the first three sentences of the full article: the ionized gas in the galaxy has been traditionally associated with bright regions surrounding hot stars , called str@xmath2mgren spheres or classical h ii regions . most h ii regions , however , are found only at low galactic latitudes with a scale height of @xmath3 pc , which is much smaller than that of the diffuse ionized gas ( dig ) or the warm ionized medium ( wim ) ( e.g. , * ? ? ? in fact , the classical h ii regions contain only @xmath4 of ionized hydrogen in the galaxy , and the remaining @xmath5 resides in warm ( @xmath6 ) and diffuse ( @xmath7 ) regions .. Please generate the next two sentences of the article

the wim occupies approximately 20 - 30 % of the volume of @xmath8-thick , plane - parallel layer of our galaxy ( e.g. , * ? ? ? * ; * ? ? ?

Suppose that you have an abstract for a scientific paper: we examine the superfluid - mott insulator ( sf - mi ) transition of antiferromagnetically interacting spin-1 bosons trapped in a square or triangular optical lattice . we perform a strong - coupling expansion up to the third order in the transfer integral @xmath0 between the nearest - neighbor lattices . as expected from previous studies , an mi phase with an even number of bosons is considerably more stable against the sf phase than it is with an odd number of bosons . results for the triangular lattice are similar to those for the square lattice , which suggests that the lattice geometry does not strongly affect the stability of the mi phase against the sf phase . . And you have already written the first three sentences of the full article: the development of optical lattice systems based on laser technology has renewed interest in strongly correlated lattice systems . one of the most striking phenomena of the optical - lattice systems is the superfluid - mott insulator ( sf - mi ) phase transition ; the sf phase ( i.e. , the coherent - matter - wave phase ) emerges when the kinetic energy is larger enough compared with the on - site repulsive interaction . otherwise , the mi phase , i.e. , the number - state phase without coherence emerges .. Please generate the next two sentences of the article

the low - lying excitations of these optical - lattice systems can be described by using the bose hubbard model . the temperature of trapped - atom systems can be extremely low , and hence , we hereafter assume the ground states of the system .

Suppose that you have an abstract for a scientific paper: in this paper we give some new criteria for identifying the components of a probability measure , in its lebesgue decomposition . this enables us to give new criteria to identify spectral types of self - adjoint operators on hilbert spaces , especially those of interest . [ theore]*theorem * [ theore]remark [ theore]proposition [ theore]lemma [ theore]definition [ theore]assumption [ theore]corollary [ theore]example [ theore]proof of theorem . And you have already written the first three sentences of the full article: let us briefly motivate our interest in determining the spectral type of a self - adjoint operator . let @xmath0 be a probability measure on the real line @xmath1 . it is well - known that this measure has a lebesgue decomposition @xmath2 , where @xmath3 is absolutely continuous with respect to the lebesgue measure on @xmath1 , @xmath4 is singular with respect to lebesgue measure , and has no atomic part , i.e. @xmath5 for all @xmath6 , and @xmath7 is purely atomic .. Please generate the next two sentences of the article

this decomposition of a probability measure has important applications in the theory of a self - adjoint operator @xmath8 on a ( separable ) hilbert space @xmath9 . associated with @xmath8 is the spectral measure @xmath10 . the spectral theorem states that we have @xmath11 if @xmath12 , then @xmath13 is a probability measure , which is supported on the spectrum @xmath14 of @xmath8 .

Suppose that you have an abstract for a scientific paper: very successful hadronization model for the production of mesons in the jets of initial quarks was proposed thirty years ago by field and feynman . the model is used so far in the design of experiments and for comparison with the experimental data . in this work it is shown that correlation function in that model , as a function of the energies of two final hadrons has interesting properties ( energies are taken in fractions of initial quark energy , and equal @xmath0 and @xmath1 , respectively ) . in particular , for some pairs of mesons there are kinematic regions over variable @xmath1 ( at fixed values of @xmath0 ) , where it is positive and unexpectedly large . the experimental investigation of the correlation functions in these kinematic regions has twofold interest , from one side it can help to investigate some delicate properties of quark jets and from the other side can help to verify the physical suppositions of model , and to obtain more precise values of parameters . . And you have already written the first three sentences of the full article: in the paper @xcite ( hereafter called ff1 ) , the authors investigated the consequences of the assumption that the high - transverse - momentum particles seen in hadron - hadron collisions are produced by a single , hard , large - angle elastic scattering of quarks , one from the target and one from the beam . the fast outgoing quarks were assumed to fragment into a cascade jet of hadrons . the distribution of quarks in the incoming hadrons were determined from lepton - hadron inelastic scattering data , together with certain theoretical constraints such as sum rules , etc .. Please generate the next two sentences of the article

the manner in which quarks cascade into hadrons was determined from particle distributions seen in lepton - hadron and lepton - lepton collisions supplemented by theoretical arguments . parameterizations for single - hadron fragmentation functions ( sff ) were obtained . in the next work @xcite a new , much simpler , parameterization for these functions was provided .

Suppose that you have an abstract for a scientific paper: this article reviews theoretical and experimental developments for one - dimensional fermi gases . specifically , the experimentally realized two - component delta - function interacting fermi gas the gaudin - yang model and its generalisations to multi - component fermi systems with larger spin symmetries . the exact results obtained for bethe ansatz integrable models of this kind enable the study of the nature and microscopic origin of a wide range of quantum many - body phenomena driven by spin population imbalance , dynamical interactions and magnetic fields . this physics includes bardeen - cooper - schrieffer - like pairing , tomonaga - luttinger liquids , spin - charge separation , fulde - ferrel - larkin - ovchinnikov - like pair correlations , quantum criticality and scaling , polarons and the few - body physics of the trimer state ( trions ) . the fascinating interplay between exactly solved models and experimental developments in one dimension promises to yield further insight into the exciting and fundamental physics of interacting fermi systems . . And you have already written the first three sentences of the full article: fundamental quantum many - body systems involve the interaction of bosonic and/or fermionic particles . the spin of a particle makes it behave very differently at ultracold temperatures below the degeneracy temperature . there are thus fundamental differences between the properties of bosons and fermions .. Please generate the next two sentences of the article

however , as bosons are not subject to the pauli exclusion principle , they can collapse under suitable conditions into the same quantum groundstate the bose - einstein condensate ( bec ) . remarkably , even a small attraction between two fermions with opposite spin states and momentum can lead to the formation of a bardeen - cooper - schrieffer ( bcs ) pair that has a bosonic nature .

Suppose that you have an abstract for a scientific paper: we study effects of direct interatomic interaction on cooperative processes in atom - photon dynamics . using a model of two - level atoms with ising - type interaction as an example , it is demonstrated that interparticle interaction combined with atom - field coupling can introduce additional interatomic correlations acting as a phase synchronizing factor . for the case of weakly interacting atoms with @xmath0 , where @xmath1 is the interparticle coupling constant and @xmath2 is the atomic frequency , dynamical regimes of cooperative relaxation of atoms are analyzed in the born - markov approximation both numerically and using the mean field approximation . we show that interparticle correlations induced by the direct interaction result in inhibition of incoherent spontaneous decay leading to the regime of collective pulse relaxation which differs from superradiance in nature . for superradiant transition , the synchronizing effect of interatomic interaction is found to manifest itself in enhancement of superradiance . when the interaction is strong and @xmath3 , one - particle one - photon transitions are excluded and transition to the regime of multiphoton relaxation occurs . using a simple model of two atoms in a high - q single mode cavity we show that such transition is accompanied by rabi oscillations involving many - atom multiphoton states . dephasing effect of dipole - dipole interaction and solitonic mechanism of relaxation are discussed . . And you have already written the first three sentences of the full article: the phenomenon of superradiance has a long history dating back more than 60 years to the seminal paper by dicke @xcite where the effect was predicted theoretically . over the past few decades the superradiance has been the subject of intense theoretical and experimental studies in a large variety of systems . these include molecular aggregates @xcite , cold atoms @xcite and bose - einstein condensates @xcite , atomic nuclei @xcite , magnetic nanoclusters @xcite , heterostructures @xcite and many others . the key process underlying the mechanism of superradiance is phase synchronization of initially independent atoms caused by the coupling with a common environment represented by the electromagnetic field . in order for such process to occur. Please generate the next two sentences of the article

the phase decoherence time of atoms should be longer than the photon travel time in the sample @xcite . for samples which size is smaller than the wavelength of radiation , this condition requires the density of atoms to be sufficiently high . the system - environment

Suppose that you have an abstract for a scientific paper: it has been recently suggested that magnetically affected neutrino oscillations inside a cooling protoneutron star , created in a supernova explosion , could explain the large proper motion of pulsars . we investigate whether this hypothesis is in agreement with the observed properties of pulsars and find that present data disfavor the suggested mechanism . the relevance of our results for other models proposed to understand the origin of pulsar velocities is also discussed . . And you have already written the first three sentences of the full article: one of the challenging problems in pulsar astrophysics is to find a consistent and observationally verified explanation for the high peculiar velocities of pulsars . these velocities can be as high as 1000 km / s and have a mean value of 450 km / s , much greater than the random velocities of ordinary stars ( harrison et al . @xcite ; lyne & lorimer @xcite ) . several mechanisms have been put forward in the past to explain the origin of the large proper motions .. Please generate the next two sentences of the article

since it is believed that pulsars are born during the first stages of some type ii or core - collapsing supernovae , an asymmetric core collapse or explosion could give the pulsars the observed velocities ( shklovskii @xcite ; woosley @xcite ; woosley & weaver @xcite ; janka & mller @xcite ; burrows & hayes @xcite ) . the evolution of close binary systems could also be responsible for the large pulsar velocities ( gott et al .

Suppose that you have an abstract for a scientific paper: we wonder whether mrzke - wheeler effects influence on measured data in nature . through a formula developed in this letter for the calculation of the mrzke - wheeler map of a general accelerated observer , we study the influence of the mrzke - wheeler acceleration effect on the nasa s pioneer anomaly and found that it is about a fifth of the anomaly value . due to statistical errors in the measured anomaly , it is not possible to neither confirm nor neglect the influence of the mrzke - wheeler acceleration effect on the measured pioneer data . we hope that the ideas presented here could encourage other research teams in the search for other observational objects that could finally answer the question posed in this letter . . And you have already written the first three sentences of the full article: nowadays , it is very clear how special relativity effects influence on measured data . the first celebrated example of this fact was the atmospheric muons decay explanation as a time dilation effect . this is the rossi - hall experiment @xcite . considering the mrzke - wheeler synchronization @xcite as the natural generalization to accelerated observers of einstein synchronization in special relativity ,. Please generate the next two sentences of the article

we wonder whether mrzke - wheeler effects influence on measured data in nature . this question is also motivated by the fact that recently the twin paradox was completely solved in ( 1 + 1)-spacetime by means of these effects @xcite and it is natural to ask for empirical confirmation .

Suppose that you have an abstract for a scientific paper: symmetry is a common feature of many combinatorial problems . unfortunately eliminating all symmetry from a problem is often computationally intractable . this paper argues that recent parameterized complexity results provide insight into that intractability and help identify special cases in which symmetry can be dealt with more tractably . . And you have already written the first three sentences of the full article: symmetry occurs in many constraint satisfaction problems . for example , in scheduling a round robin sports tournament , we may be able to interchange all the matches taking place in two stadia . similarly , we may be able to interchange two teams throughout the tournament . as a second example , when colouring a graph ( or equivalently when timetabling exams ) , the colours are interchangeable. Please generate the next two sentences of the article

. we can swap red with blue throughout . if we have a proper colouring , any permutation of the colours is itself a proper colouring .

Suppose that you have an abstract for a scientific paper: the dynamical heterogeneities ( dh ) in non - ergodic states of an attractive colloidal glass are studied , as a function of the waiting time . whereas the fluid states close to vitrification showed strong dh , the distribution of squared displacements of the glassy states studied here only present a tail of particles with increased mobility for the lower attraction strength at short waiting times . these particles are in the surface of the percolating cluster that comprises all of the particles , reminiscent of the fastest particles in the fluid . the quench deeper into the attractive glass is dynamically more homogeneous , in agreement with repulsive glasses ( i.e. lennard - jones glass ) . , , 64.70.pf , 82.70.dd , 61.20.lc . And you have already written the first three sentences of the full article: two distinct glasses have been predicted and identified in hard spheres with short range attractions : a repulsion driven glass at high density , and an attraction driven one , formed at low temperatures ( or high attraction strength ) @xcite . whereas the former one is caused by the steric hindrance of the particle cores and the so - called _ cage effect _ , the latter forms due to the bonding between particles . this system is realized experimentally by a colloid - polymer mixture , where the effect of the polymers is to induce an effective attraction between the colloids @xcite . both glasses have been indeed identified , although the attractive one , which at low concentrations is termed ` gel ' , often competes with ( and inhibits ) liquid - gas phase separation @xcite . dynamical heterogeneities ( dh ). Please generate the next two sentences of the article

have been found in the proximity of repulsion driven glass transitions by computer simulations , i.e. in lennard - jones mixtures @xcite , or hard spheres @xcite . in these cases , while the system is structurally liquid - like ( homogeneous ) , a population of particles of increased mobility is observed . as the glass transition is approached from the fluid side , the heterogeneities become more pronounced , but decrease again deeper in the glass @xcite . the role of these dynamical heterogeneities in the glass transition

Suppose that you have an abstract for a scientific paper: using recent polarimetric observations of the crab nebula in the hard x - ray band by integral , we show that the absence of vacuum birefringence effects constrains @xmath0 lorentz violation in qed to the level @xmath1 at @xmath2 cl , tightening by more than three orders of magnitude previous constraints . we show that planned x - ray polarimeters have the potential to probe @xmath3 by detecting polarization in active galaxies at red - shift @xmath4 . experimental constraints on the parameters quantifying lorentz invariance violation ( lv ) are of fundamental importance . because the lowest order corrections predicted in the photon dispersion relation imply the vacuum is birefringent , observations of polarized photons from distant astronomical sources provide very promising tests . in this letter we exploit the recently discovered linear polarization of hard x - rays from the crab nebula ( cn ) @xcite . these observations show a remarkably high degree of linear polarization ( @xmath5 ) and very close alignment of the polarization vector with both the optical polarization vector and the projection on the sky of the spin axis of the central neutron star . the high degree of polarization together with the lack of detectable rotation of the polarization vector of these @xmath6kev photons whilst propagating over the intervening @xmath7 cm enables us to tighten existing constraints by three orders of magnitude . recent years have witnessed a growing interest in the possible high energy violations of local lorentz invariance as well as a flourishing of observational tests . indeed , specific hints of lv arose from various approaches to quantum gravity @xcite . however , most tests require a well established theoretical framework to calculate reaction rates and describe the particle dynamics . here , we work within the framework of effective field theory with non - renormalizable , mass dimension 5 lv operators ( see @xcite and references therein ) restricted to qed , for which the most.... And you have already written the first three sentences of the full article: lm , sl and ac acknowledge the italian miur for financial support . pu wishes to thank a.j . dean and j.b . stephen for useful scientific discussions .. Please generate the next two sentences of the article

Suppose that you have an abstract for a scientific paper: the unitarity of a lorentz - invariance violating qed model with higher - order myers and pospelov photons coupled to standard fermions is studied . as expected , we find ghost states associated to the higher - order terms that may lead to the loss of unitarity . an explicit calculation to check perturbative unitarity in the process of electron - positron scattering is performed and it is found to be possible to be preserved . . And you have already written the first three sentences of the full article: in recent years , higher - order operators have become the object of intense study in the search for possible effects of lorentz invariance violation @xcite . these planck - mass suppressed higher - order operators allows to describe new physics beyond those obtainable from renormalizable operators , that is , operators with mass dimension four or less @xcite . for example , the higher - order effective theory may involve additional degrees of freedom associated to ultra - high energies which do not converge perturbatively to the normal ones when taking the limit of the dimensionless parameters in the effective terms to zero .. Please generate the next two sentences of the article

lee and wick studied these exotic modes in the context of negative metric theories @xcite and in spite of the ghost states that appear , they showed that unitarity can be preserved by demanding all stable particles to be positive norm states @xcite . here we check perturbative unitarity in a qed consisting of higher - order myers and pospelov photons @xcite and standard fermions .

Suppose that you have an abstract for a scientific paper: i use a library of controlled minor merger n - body simulations , a particle tagging technique and monte carlo generated @xmath0cdm accretion histories to study the highly stochastic process of stellar deposition onto the accreted stellar halos ( ashs ) of @xmath1 galaxies . i explore the main physical mechanisms that drive the connection between the accretion history and the density profile of the ash . i find that : i ) through dynamical friction , more massive satellites are more effective at delivering their stars deeper into the host ; ii ) as a consequence , ashs feature a negative gradient between radius and the local mass - weighed virial satellite - to - host mass ratio ; iii ) in @xmath1 galaxies , most ashs feature a density profile that steepens towards sharper logarithmic slopes at increasing radii , though with significant halo - to - halo scatter ; iv ) the ashs with the largest total ex - situ mass are such because of the chance accretion of a small number of massive satellites ( rather than of a large number of low - mass ones ) . . And you have already written the first three sentences of the full article: the accreted stellar halo ( ash ) of a galaxy represents a record of the accretion history of the galaxy itself . its assembly is determined by a large number of free parameters , including the structural properties of each accreted satellite ( virial mass , concentration , stellar content , morphology ) , the orbital properties of each accretion event ( energy and angular momentum at infall ) , the structural properties of the host itself during accretion . this implies a significant degree of stochasticity , as shown by the observed halo - to - halo scatter ( e.g. , van dokkum et al .. Please generate the next two sentences of the article

2014 ) and by the dichotomy between the ` broken ' and sharply declining density profile of the stellar halo of the milky way ( e.g. , deason et al . 2013 ) and the more extended halo of andromeda , whose density profile is well described by a single power - law ( e.g. , gilbert et al .

Suppose that you have an abstract for a scientific paper: the caustic technique measures the mass of galaxy clusters in both their virial and infall regions and , as a byproduct , yields the list of cluster galaxy members . here we use @xmath0 galaxy clusters with mass @xmath1 extracted from a cosmological @xmath2-body simulation of a @xmath3cdm universe to test the ability of the caustic technique to identify the cluster galaxy members . we identify the true three - dimensional members as the gravitationally bound galaxies . the caustic technique uses the caustic location in the redshift diagram to separate the cluster members from the interlopers . we apply the technique to mock catalogs containing 1000 galaxies in the field of view of @xmath4 mpc on a side at the cluster location . on average , this sample size roughly corresponds to 180 real galaxy members within @xmath5 , similar to recent redshift surveys of cluster regions . the caustic technique yields a completeness , the fraction of identified true members , @xmath6 within @xmath5 . the contamination , the fraction of interlopers in the observed catalog of members , increases from @xmath7 at @xmath8 to @xmath9 at @xmath5 . no other technique for the identification of the members of a galaxy cluster provides such large completeness and small contamination at these large radii . the caustic technique assumes spherical symmetry and the asphericity of the cluster is responsible for most of the spread of the completeness and the contamination . by applying the technique to an approximately spherical system obtained by stacking the individual clusters , the spreads decrease by at least a factor of two . we finally estimate the cluster mass within @xmath5 after removing the interlopers : for individual clusters , the mass estimated with the virial theorem is unbiased and within 30% of the actual mass ; this spread decreases to less than 10% for the spherically symmetric stacked cluster . cosmology : miscellaneous dark matter galaxies : clusters : general gravitation large - scale.... And you have already written the first three sentences of the full article: galaxy clusters provide crucial information to our understanding of the large - scale cosmic structure and to constrain cosmological models . they populate the high - mass tail of the mass function of virialized galaxy systems ; their abundance and redshift distribution depend on the average density of the universe and the normalization of the power spectrum of the initial density perturbations ( e.g. , * ? ? ? * ; * ? ? ?. Please generate the next two sentences of the article

* ; * ? ? ? clusters are a hostile environment to galaxies and are thus also a unique tool to investigate the connection between environment and galaxy properties ( e.g. , * ? ? ?

Suppose that you have an abstract for a scientific paper: we present an extended study of single impurity atoms at the interface between the half - metallic ferromagnetic zinc - blende cras compound and the zinc - blende binary inas and cdse semiconductors in the form of very thin multilayers . contrary to the case of impurities in the perfect bulk cras studied in [ i. galanakis and s.g . pouliasis , j. magn . magn . mat . 321 ( 2009 ) 1084 ] defects at the interfaces do not alter in general the half - metallic character of the perfect systems . the only exception are void impurities at cr or in(cd ) sites which lead , due to the lower - dimensionality of the interfaces with respect to the bulk cras , to a shift of the @xmath0 bands of the nearest neighboring as(se ) atom to higher energies and thus to the loss of the half - metallicity . but void impurities are schottky - type and should exhibit high formation energies and thus we expect the interfaces in the case of thin multilayers to exhibit a robust half - metallic character . electronic structure , half - metals , cras 75.47.np , 75.50.cc , 75.30.et . And you have already written the first three sentences of the full article: the discovery of giant magnetoteresistance in 1998 by the groups of fert and grnberg led to new reading heads for hard disks @xcite . moreover for the first time , a device based on magnetic phenomena replaced a conventional electronics device based on the movement of the electrons charge and thus opened the way to the field of spintronics or magnetoelectronics . the aim is to replace conventional electronics with new devices where magnetism plays a central role leading to smaller energy consumption . several architectures have been proposed @xcite but only in 2009 dash and collaborators managed to inject spin - polarized current from a metallic electrode into si , which is a key issue in current research in this field . showing that spintronic devices can be incorporated into conventional electronics @xcite . in order to maximize the efficiency of spintronic devices ,. Please generate the next two sentences of the article

the injected current should have as high spin - polarization as possible @xcite . to this respect half - metallic compounds have attracted a lot of interest ( for a review see reference @xcite ) .

Suppose that you have an abstract for a scientific paper: the purpose of this work is simulation of magnetised plasmas in the iter project framework . in this context , kinetic vlasov - poisson like models are used to simulate core turbulence in the tokamak in a toroidal geometry . this leads to heavy simulations because a 6d dimensional problem has to be solved , even if reduced to a 5d in so called gyrokinetic models . accurate schemes , parallel algorithms need to be designed to bear these simulations . this paper describes the numerical studies to improve robustness of the conservative psm scheme in the context of its development in the gysela code . in this paper , we only consider the 4d drift - kinetic model which is the backbone of the 5d gyrokinetic models and relevant to build a robust and accurate numerical method . numerical simulation , conservative scheme , maximum principle , plasma turbulence 65m08 , 76m12 , 76n99 . And you have already written the first three sentences of the full article: the iter device is a tokamak designed to study controlled thermonuclear fusion . roughly speaking , it is a toroidal vessel containing a magnetised plasma where fusion reactions occur . the plasma is kept out of the vessel walls by a magnetic field which lines have a specific helicoidal geometry. Please generate the next two sentences of the article

. however , turbulence develops in the plasma and leads to thermal transport which decreases the confinement efficiency and thus needs a careful study . plasma is constituted of ions and electrons , which motion is induced by the magnetic field .

Suppose that you have an abstract for a scientific paper: we prove an infinite - dimensional generalization of zenger s lemma that was used in the proof of the fact that the convex hull of the point spectrum of a linear operator is contained in its numerical range . two relevant examples are given , and possible application in the arrow - debreu model is also discussed . 6.6 mm norms , sequence spaces , arrow - debreu model . And you have already written the first three sentences of the full article: in 1968 , zenger @xcite proved the following result that is known as zenger s lemma . [ zenger_finite ] let @xmath0 be a norm on @xmath1 , let @xmath2 for all @xmath3 , and let @xmath4 . then there exists a vector @xmath5 with @xmath6 and @xmath7 such that the functional @xmath8 on @xmath1 defined by @xmath9 has norm one .. Please generate the next two sentences of the article

zenger applied theorem [ zenger_finite ] in the proof of the fact that the convex hull of the point spectrum of a linear operator is contained in its numerical range ; see also ( * ? ? ? * section 19 ) .

Suppose that you have an abstract for a scientific paper: we theoretically give an infinite number of metastable crystal structures for the superconducting sulfur hydride h@xmath0s under pressure . previously predicted crystalline phases of h@xmath1s and h@xmath2s have been thought to have important roles for the experimentally observed low and high @xmath3 , respectively . the newly found structures are long - period modulated crystals where slab - like h@xmath1s and h@xmath2s regions intergrow in a microscopic scale . the extremely small formation enthalpy for the h@xmath1s h@xmath2s boundary indicated with the first - principles calculations suggests possible alloying of these phases through formation of local h@xmath2s regions . the modulated structures and gradual alloying transformations between them explain peculiar pressure dependence of @xmath3 in sulfur hydride observed experimentally , as well as could they prevail in the experimental samples under various compression schemes . sulfur hydride has recently been found to become superconductor at extremely high pressure around 200 k @xcite . this is the first achievement of superconducting transition temperature ( @xmath3 ) exceeding the nitrogen boiling point among the conventional phonon mediated superconductors @xcite , as well as it has broken the long - standing record of 160 k in mercury - cuprate @xcite . a remarkable feature observed in this superconducting phenomenon is pressure and annealing - scheme dependences of @xmath3 @xcite . ( i ) when the pressure ( @xmath4@xmath5100 gpa ) is applied to the h@xmath1s sample at room temperatures and afterwards cooled down , the observed @xmath3s amount to over 150 k , with 203k being the maximum value ( open circle in fig . [ fig : crystals ] ) . ( ii ) by pressurizing at temperature around 100 k , on the other hand , the observed @xmath3 remains low and next rapidly increases ( open square in fig . [ fig : crystals ] ) . although this behavior suggests a variety of structural phases and their peculiar properties ,.... And you have already written the first three sentences of the full article: " . ] here we summarize which permutations yield equivalent and nonequivalent metastable structures . ( i ) the cyclic variants of any permutations give equivalent structures because of the periodicity of the crystal . ( ii ) pairs of permutations exchanged by @xmath68 ( e.g. , @xmath69 " and @xmath70 " ) yield pairs of structures exchanged by the mirror plane @xmath71 ( plane perpendicular to the units , see fig .. Please generate the next two sentences of the article

s[fig : permutation - op ] ) . ( iii ) pairs of permutations exchanged by inversion ( e.g. , @xmath69 " and @xmath72 " ) yields structures interchanged by global inversion ( @xmath73 ) .

Suppose that you have an abstract for a scientific paper: i review how the top quark is embedded in the standard model and some its proposed extensions , and how it manifests itself in various hadron collider signals . . And you have already written the first three sentences of the full article: of the particles seen so far in collider experiments , the top quark is no doubt the most expensive , and the most glamorous . it is therefore the center of attention at the tevatron and the lhc , until of course a new star , higgs , comes along . expressed less colloquially , the top quark is considered an interesting study object because it has many quantum numbers and thus couples to almost all other particles , through various ( chiral , vector , scalar ) structures , all of which bear scrutiny for deviations .. Please generate the next two sentences of the article

precise scrutiny is feasible because the large top mass implies , first , that it couples strongly to whatever breaks the electroweak symmetry , and second , the resulting large width minimizes obscuring hadronization effects and allows preservation of spin information . top is also a troublemaker for the standard model , contributing significantly to the quadratic divergences of the higgs self energy , but is at the same time an life raft for beyond the standard model ( bsm ) theories such as the mssm ( raising the upper limit on the light higgs in that theory ) . with