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Suppose that you have an abstract for a scientific paper: we demonstrate how measuring orbital period derivatives can lead to more accurate distance estimates and transverse velocities for some nearby binary pulsars . in many cases this method will estimate distances more accurately than is possible by annual parallax , as the relative error decreases as @xmath0 . unfortunately , distance uncertainties limit the degree to which nearby relativistic binary pulsars can be used for testing the general relativistic prediction of orbital period decay to a few percent . nevertheless , the measured orbital period derivative of psr b1534 + 12 agrees within the observational uncertainties with that predicted by general relativity if the proper - motion contribution is accounted for . . And you have already written the first three sentences of the full article: the most common method for determining the distances to radio pulsars is based on their dispersion measure and models of the galactic distribution of free electrons ( @xcite ) . these distance estimates typically have an uncertainty of 30% . distances may also be determined by measuring annual parallax , based on either timing ( @xcite ) or interferometric measurements ( @xcite ) .. Please generate the next two sentences of the article

hi absorption by interstellar hydrogen is also a common distance indicator ( @xcite ) . however , no pulsar has a distance estimate more accurate than @xmath2% , and for all but two , the errors are greater than 20% .

Suppose that you have an abstract for a scientific paper: we consider interacting spinless fermions in one dimension embedded in self - similar quasiperiodic potentials . we examine generalizations of the fibonacci potential known as precious mean potentials . using a bosonization technique and a renormalization group analysis , we study the low - energy physics of the system . we show that it undergoes a metal - insulator transition for any filling factor , with a critical interaction that strongly depends on the position of the fermi level in the fourier spectrum of the potential . for some positions of the fermi level the metal - insulator transition occurs at the non interacting point . the repulsive side is an insulator with a gapped spectrum whereas in the attractive side the spectrum is gapless and the properties of the system are described by a luttinger liquid . we compute the transport properties and give the characteristic exponents associated to the frequency and temperature dependence of the conductivity . . And you have already written the first three sentences of the full article: the electronic properties of quasicrystals@xcite have revealed the importance of the non crystalline order at the atomic level . indeed , the conductivity @xmath0 of these metallic alloys displays a unusual behavior since it increases when either temperature or disorder increases . it is also surprisingly low compared to that of the metals that composed them . from a theoretical point of view , the influence of quasiperiodicity on the spectral and dynamical properties of electron systems has been the subject of many studies . for independent electrons systems. Please generate the next two sentences of the article

, it has been shown that the eigenstates , which are neither localized nor extended but critical ( algebraic decay ) , are responsible of an anomalous quantum diffusion in any dimension . concerning the nature of the spectrum , it depends on the dimensionality but also exhibits specific characteristics of the quasiperiodicity . more precisely , in one dimension , the spectrum of quasiperiodic systems , such as the fibonacci or the harper chain , is made up of an infinite number of zero width bands ( singular continuous ) whereas in higher dimensions , it can be either absolutely continuous ( band - like ) , singular continuous , or any mixture .

Suppose that you have an abstract for a scientific paper: we study the luminosity function and the correlation function of about 1200 z@xmath04 lyman break galaxies ( lbgs ) with @xmath1 that are photometrically selected from deep @xmath2 imaging data of a 618 arcmin@xmath3 area in the subaru / xmm - newton deep field taken with subaru prime focus camera . the contamination and completeness of our lbg sample are evaluated , on the basis of the hubble deep field - north ( hdf - n ) objects , to be 17% and 45% , respectively . we derive the uv ( rest 1700 ) luminosity functions ( lfs ) and find a large population of uv - luminous galaxies at @xmath4 . the lfs of the red and blue subsamples imply that the bright lbgs are redder in the uv continuum than the average color of the lbgs . then we calculate the correlation function over @xmath5 and find that it is fitted fairly well by a power law , @xmath6 , with @xmath7 . we estimate the correlation length @xmath8 ( in comoving units ) of the two - point spatial correlation function @xmath9 to be @xmath10 @xmath11mpc ( @xmath12 and @xmath13 ) . the correlation function shows an excess of @xmath14 on small scales ( @xmath15 ) , departing from the power - law fit at @xmath16 significance level . interpreting this as being due to galaxy mergers , we evaluate the fraction of galaxies undergoing mergers to be @xmath17 , which is significantly smaller than those of galaxies at intermediate redshifts . . And you have already written the first three sentences of the full article: in the past several years , deep field surveys have made remarkable breakthroughs in studies on high redshift galaxies . the most successful survey would be the hubble deep fields which are deep enough to study high-_z _ galaxies up to @xmath18 . many efforts on spectroscopic and photometric follow - up observations reveal hundreds of high-_z _ galaxies and their properties ( e.g.@xcite ) .. Please generate the next two sentences of the article

however the surveyed areas of hdfs are as small as a few arcmin@xmath3 each , so they may be affected by field - to - field variations . steidel and his collaborators have pioneered in statistical studies of high-_z _ galaxies based on ground - based wide survey data @xcite .

Suppose that you have an abstract for a scientific paper: results of two years of continuous monitoring of flux density variations at 8.3 and 2.3 ghz of the galactic center super - massive black hole candidate sgr a * are reported . the average rms modulation indices are 6% and 2.5% at 8.3 & 2.3 ghz respectively . there is a certain degree of correlation between both frequencies . the timescale of variability at 8.3 & 2.3 ghz is between 50 and 200 days . we can not confirm a @xmath0 dependence of the timescale . at 2.3 ghz a quasi - periodic behaviour with a period of 57 days was discovered which is reminiscent to , though longer than , those found in some compact extragalactic radio sources . . And you have already written the first three sentences of the full article: sgr a * is believed to be the radio source associated with the @xmath1 ( haller et al . 1996 ; ghez et al . 1998 & 1999 ; eckart & genzel 1996 ; genzel & eckart 1999 ; zhao & goss 1999 ) dark mass concentration in the center of the galaxy . since we know very little about this source from other wavelengths , where it is extremely faint ( see falcke 1996 for a review ) , a detailed study of its radio properties is an important prerequisite for its interpretation .. Please generate the next two sentences of the article

the overall shape of the sgr a * radio spectrum has been discussed in many papers ( e.g. , serabyn et al . 1997 ; falcke et al .

Suppose that you have an abstract for a scientific paper: recent results of the kascade air shower experiment are presented in order to shed some light on the astrophysics of cosmic rays in the region of the knee in the energy spectrum . the results include investigations of high - energy interactions in the atmosphere , the analysis of the arrival directions of cosmic rays , the determination of the mean logarithmic mass , and the unfolding of energy spectra for elemental groups . . And you have already written the first three sentences of the full article: the origin of high - energy cosmic rays is among the most interesting questions in astrophysics . the origin of a structure in the all - particle energy spectrum around 4 pev , the so - called knee , is generally believed to be a corner stone in the understanding of the astrophysics of high - energy cosmic rays . the knee is proposed to be caused by the maximum energy reached in cosmic - ray accelerators or due to leakage of particles from the galaxy .. Please generate the next two sentences of the article

hence , an understanding of the origin of the knee reveals hints on the acceleration and propagation of cosmic rays . experimental access to the understanding of the sources , acceleration and propagation mechanisms is provided by detailed investigation of the arrival directions , energy spectra , and mass composition of the ultrarelativistic particles . while at energies below 1 pev cosmic rays can be measured directly at the top of the atmosphere

Suppose that you have an abstract for a scientific paper: many models of physics beyond the standard model yield exotic higgs decays . some of these , particularly those in which the higgs decays to light quarks or gluons , can be very difficult to discover experimentally . here we introduce a new set of jet substructure techniques designed to search for such a higgs when its dominant decay is into gluons via light , uncolored resonances . we study this scenario in both @xmath0 and @xmath1 production channels , and find both channels lead to discovery at the lhc with @xmath2 at @xmath3 . . And you have already written the first three sentences of the full article: discovering the higgs boson is one of the main physics goals of the lhc program . while collider search strategies have been well developed for the standard model ( sm ) higgs , the presence of new light degrees of freedom can dramatically alter higgs phenomenology . for instance , in a class of models with an extended higgs sector , the higgs can decay via the cascade @xmath4 , where @xmath5 is an on - shell pseudoscalar and @xmath6 is a sm state to which the pseudoscalar decays .. Please generate the next two sentences of the article

when this decay dominates , the branching fractions into the standard discovery channels such as @xmath7 are very suppressed , and new lhc strategies have to be developed to discover the higgs . previous studies have considered the pseudoscalar decaying into @xmath8 , @xmath9 , @xmath10 , and @xmath11 @xcite .

Suppose that you have an abstract for a scientific paper: raman spectra are reported for ba doped fullerides , @xmath0 ( x=3 , 4 , and 6 ) . the lowest frequency @xmath1 modes split into five components for @xmath2 and @xmath3 even at room temperature , allowing us a quantitative analysis based on the electron - phonon coupling theory . for the superconducting @xmath2 , the density of states at the fermi energy was derived as 7 @xmath4 , while the total value of electron - phonon coupling @xmath5 was found to be 1.0 , which is comparable to that of @xmath6 . the tangential @xmath7 mode , which is known as a sensitive probe for the degree of charge transfer on @xmath8 molecule , shows a remarkable shift depending on the ba concentration , being roughly consistent with the full charge transfer from ba to @xmath8 . an effect of hybridization between ba and @xmath8 @xmath9 orbitals is also discussed . = 10000 * pacs numbers : 78.30.-j , 72.80.rj , 74.70.-b * . And you have already written the first three sentences of the full article: since the discovery of superconductivity in alkali - metal doped @xmath8 , extensive research on @xmath8 and other fullerenes has been carried out worldwide , aiming at understanding the mechanism for superconductivity and other related issues in fullerenes.@xcite most of the theoretical models assumed that electron - phonon interaction is important for superconductivity.@xcite based on the analysis of the linewidths in vibronic spectra excited either by light ( raman scattering ) or by neutrons , the electron - phonon coupling constant @xmath5 for @xmath10 ( a = alkali metal ) has been estimated . recently , winter and kuzmany observed that the low frequency @xmath11 and @xmath12 modes lose all degeneracy and split into five components , each of which couples differently to the @xmath13 electrons for single crystal of @xmath6 at 80 k.@xcite these results revealed that in the superconducting state , the pairing is mediated by phonons with weak or intermediate coupling . @xcite the lowest two unoccupied molecular orbitals of @xmath8 are both triply degenerated , having @xmath13 and @xmath14 symmetry .. Please generate the next two sentences of the article

filling of @xmath13 and @xmath14 bands with electrons is achieved by intercalation of alkali metals and alkaline earth metals to @xmath8 solids , respectively . nevertheless , understanding of the `` @xmath14 superconductors '' is extremely poor in comparison with the well known @xmath13 superconductors .

Suppose that you have an abstract for a scientific paper: we investigate the evolution of the raman spectrum of defected graphene as a function of doping . polymer electrolyte gating allows us to move the fermi level up to 0.7ev , as monitored by _ in - situ _ hall - effect measurements . for a given number of defects , the intensities of the d and d peaks decrease with doping . we assign this to an increased total scattering rate of the photoexcited electrons and holes , due to the doping - dependent strength of electron - electron scattering . we present a general relation between d peak intensity and defects valid for any doping level . . And you have already written the first three sentences of the full article: raman spectroscopy is one of the most used characterization techniques in carbon science and technology@xcite . the measurement of the raman spectrum of graphene@xcite triggered a huge effort to understand phonons , electron - phonon , magneto - phonon and electron - electron interactions in graphene , as well as the influence of the number and orientation of layers , electric or magnetic fields , strain , doping , disorder , quality and types of edges , and functional groups@xcite . quantifying defects in graphene is crucial both to gain insight in fundamental properties , and for applications . ref . introduced a three - stage classification of disorder , leading from graphite to amorphous carbons , that allows to simply assess all the raman spectra of carbons : stage 1 ) graphene to nanocrystalline graphene ; stage 2 ) nanocrystalline graphene to low-@xmath0 amorphous carbon ; stage 3 ) low-@xmath0 amorphous carbon to high-@xmath0 amorphous carbon . here. Please generate the next two sentences of the article

we focus on stage 1 , the most relevant when considering the vast majority of publications dealing with graphene production , processing and applications . in stage 1 the raman spectrum evolves as follows@xcite : a ) d appears and the ratio of the d and g peak intensities , i(d)/i(g ) , increases ; b ) d appears ; c ) all peaks broaden ; e ) the d+d peak appears ; f ) at the end of stage 1 , g and d are so wide that is sometimes more convenient to consider them as a single , up - shifted , wide g band at@xmath1 . in their seminal work , tuinstra and

Suppose that you have an abstract for a scientific paper: tropical algebraic geometry is a degeneration of classical geometry which loose the property of unique factorization for polynomials . in this paper we explore a structure that is known to be a semi - degeneration between the classical algebra and the tropical algebra , and show that unique factorization fails in several variables due to geometric reasons , not just algebraic . we also show that unique factorization does hold for a certain interesting subset of polynomials . . And you have already written the first three sentences of the full article: we wish to study algebraic geometry over the max - plus or tropical algebra . in order to do so , we should look at roots of polynomials . + the common definition for tropical roots of polynomials is a point of equality between two monomials or more ( ref .. Please generate the next two sentences of the article

@xcite,@xcite ) . izhakian has built a structure that defines the sum of two equal elements as a ghost " element , and treats these ghosts as zeros since we want to view them as roots . + further research led izhakian and rowen ( @xcite ) to the idea of a graded algebra . not only

Suppose that you have an abstract for a scientific paper: we numerically construct the bps and non - bps wavefunctions of an @xmath0 quiver quantum mechanics with two abelian nodes and a single arrow . this model captures the dynamics of a pair of wrapped d - branes interacting via a single light string mode . a dimensionless parameter @xmath1 , which is inversely proportional to the the fayet - iliopoulos parameter , controls whether the bulk of the wavefunctions are supported on the higgs branch or the coulomb branch . we demonstrate how the bps and excited states morph as @xmath1 is tuned . we also numerically compute the energy gap between the ground state and the first excited states as a function of @xmath1 . an expression for the the gap , computed on the coulomb branch , matches nicely with our numerics at large @xmath1 but deviates at small @xmath1 where the higgs branch becomes the relevant description of the physics . in the appendix , we provide the schrdinger equations fully reduced via symmetries which , in principle , allow for the numerical determination of the entire spectrum at any point in moduli space . for the ground states , this numerical determination of the spectrum can be thought of as the first _ in silico _ check of various witten index calculations . mit - ctp-4731 susy in silico : numerical d - brane bound state spectroscopy tarek anous _ center for theoretical physics , massachusetts institute of technology , cambridge , ma 02139 , usa _ . And you have already written the first three sentences of the full article: the low - energy effective theory describing the dynamics of a collection of wrapped d - branes at small separations is given by quiver quantum mechanics @xcite . these d - branes form bound states and , depending on parameters , can either be well separated or on top of each other . when well separated , the theory is on the coulomb branch , parametrized by a macroscopic vev @xmath2 for the fields describing the separation between the branes . conversely , when the branes are on top of each other , the theory is on the higgs branch , parametrized by a large vev @xmath3 for the field representing the light stretched string mode between the branes . in this paper we will consider the simplest example of quiver quantum mechanics , describing the dynamics of a pair of d - branes with a single light stretched string mode between them . being a supersymmetric theory ,. Please generate the next two sentences of the article

the relative separation between the branes lives in a vector multiplet @xmath4 and the lightest stretched string mode lives in a chiral multiplet @xmath5 . these models have proven fruitful playgrounds for the study of supersymmetric black hole bound states at weak coupling @xcite .

Suppose that you have an abstract for a scientific paper: we discuss israel layers collapsing inward from rest at infinity along schwarzschild - lemaitre geodesics . the dynamics of the collapsing layer and its equation of state are developed . there is a general equation of state which is approximately polytropic in the limit of very low pressure . the equation of state establishes a new limit on the stress - density ratio . . And you have already written the first three sentences of the full article: since their introduction , israel layers @xcite,@xcite,@xcite have played an increasingly important role in gravitational physics . barrabes and israel @xcite began their paper with a description of the israel layer as a thermodynamic phase boundary , but the initial applications of israel layers considered metric matching in dynamic collapse processes involving dust shells , null shells , and cosmic string loops @xcite,@xcite,@xcite . poisson @xcite has summarized some of the early seminal work by israel @xcite,@xcite , barrabes @xcite , de la cruz @xcite , musgrave and lake @xcite , and barrabes and hogan @xcite .. Please generate the next two sentences of the article

the israel junction conditions @xcite,@xcite find wide application because they provide a simple dynamic boundary description for a variety of scenarios @xcite . the use of layers as boundaries between standard metrics has been summarized by ansoldi @xcite , and there is a growing literature that applies the thin shell formalism to new areas such as shell quantum mechanics @xcite - @xcite , layer dimensionality @xcite,@xcite,@xcite , layers in extensions of general relativity @xcite - @xcite and matching in perturbed spacetimes @xcite - @xcite .

Suppose that you have an abstract for a scientific paper: we carry out a model independent study of resonant photon scattering off dark matter ( dm ) particles . the dm particle @xmath0 can feature an electric or magnetic transition dipole moment which couples it with photons and a heavier neutral particle @xmath1 . resonant photon scattering then takes place at a special energy @xmath2 set by the masses of @xmath0 and @xmath1 , with the width of the resonance set by the size of the transition dipole moment . we compute the constraints on the parameter space of the model from stellar energy losses , data from sn 1987a , the lyman-@xmath3 forest , big bang nucleosynthesis , electro - weak precision measurements and accelerator searches . we show that the velocity broadening of the resonance plays an essential role for the possibility of the detection of a spectral feature originating from resonant photon - dm scattering . depending upon the particle setup and the dm surface mass density , the favored range of dm particle masses lies between tens of kev and a few mev , while the resonant photon absorption energy is predicted to be between tens of kev and few gev . . And you have already written the first three sentences of the full article: one of the crucial properties of the _ dark _ matter ( dm ) is the feebleness of its coupling to the electromagnetic field . the early decoupling of dm from the baryon - photon fluid is a basic ingredient of the current picture of structure formation , and various direct dm detection experiments set stringent limits on the coupling of dm with ordinary matter . the phenomenological possibilities of a charged @xcite , or a milli - charged @xcite dm species , or that of dm featuring an electric or magnetic dipole moment @xcite were considered in several recent studies , all pointing towards a severe suppression of any coupling of the dm with photons . significant absorption or scattering of photons by dm appears to ruled out , perhaps implying that _ dm does not cast shadows_. in this analysis we investigate the possibility that , while the typical scattering cross section of dm with photons is very small , photons with the right energy can resonantly scatter off dm particles .. Please generate the next two sentences of the article

we show that this resonant scattering might result in peculiar absorption features in the spectrum of distant sources . this effect can occur if the extension of the standard model of particle physics required to accommodate a ( neutral ) dm particle candidate @xmath0 also encompasses ( 1 ) a second , heavier neutral particle @xmath1 and ( 2 ) an electric and/or magnetic transition dipole moment which couples the electromagnetic field to @xmath0 and @xmath1 .

Suppose that you have an abstract for a scientific paper: we investigate hadron production and transverse hadron spectra in nucleus - nucleus collisions from 2 @xmath0gev to 21.3 @xmath0tev within two independent transport approaches ( urqmd and hsd ) based on quark , diquark , string and hadronic degrees of freedom . the enhancement of pion production in central au+au ( pb+pb ) collisions relative to scaled @xmath1 collisions ( the kink ) is described well by both approaches without involving a phase transition . however , the maximum in the @xmath2 ratio at 20 to 30 a@xmath3gev ( the horn ) is missed by @xmath4 40% . also , at energies above @xmath4 5 a@xmath3gev , the measured @xmath5 @xmath6-spectra have a larger inverse slope than expected from the models . thus the pressure generated by hadronic interactions in the transport models at high energies is too low . this finding suggests that the additional pressure - as expected from lattice qcd at finite quark chemical potential and temperature - might be generated by strong interactions in the early pre - hadronic / partonic phase of central heavy - ion collisions . finally , we discuss the emergence of density perturbations in a first - order phase transition and why they might affect relative hadron multiplicities , collective flow , and hadron mean - free paths at decoupling . a minimum in the collective flow @xmath7 excitation function was discovered experimentally at 40 a@xmath3gev - such a behavior has been predicted long ago as signature for a first order phase transition . . And you have already written the first three sentences of the full article: the phase transition from partonic degrees of freedom ( quarks and gluons ) to interacting hadrons is a central topic of modern high - energy physics . in order to understand the dynamics and relevant scales of this transition laboratory experiments under controlled conditions are presently performed with ultra - relativistic nucleus - nucleus collisions . hadronic spectra and relative hadron abundancies from these experiments reflect important aspects of the dynamics in the hot and dense zone formed in the early phase of the reaction .. Please generate the next two sentences of the article

furthermore , as has been proposed early by rafelski and mller @xcite the strangeness degree of freedom might play an important role in distinguishing hadronic and partonic dynamics . in fact , estimates based on the bjorken formula @xcite for the energy density achieved in central au+au collisions suggest that the critical energy density for the formation of a quark - gluon plasma ( qgp ) is by far exceeded during a few fm / c in the initial phase of the collision at relativistic heavy ion collider ( rhic ) energies @xcite , but sufficient energy densities ( @xmath4 0.7 - 1 gev/@xmath8 @xcite ) might already be achieved at alternating gradient synchrotron ( ags ) energies of @xmath4 10 @xmath0gev @xcite .

Suppose that you have an abstract for a scientific paper: high - statistics data on near - horizontal muons collected with russian - italian coordinate detector decor are analyzed . precise measurements of muon angular distributions in zenith angle interval from 60@xmath0 to 90@xmath0 have been performed . in total , more than 20 million muons are selected . dependences of the absolute integral muon intensity on zenith angle for several threshold energies ranging from 1.7 gev to 7.2 gev are derived . results for this region of zenith angles and threshold energies have been obtained for the first time . the dependence of integral intensity on zenith angle and threshold energy is well fitted by a simple analytical formula . . And you have already written the first three sentences of the full article: studies of angular and energy dependence of muon flux at the earth s surface give important information as about processes of muon generation and propagation in the atmosphere so about primary cosmic rays . measurements of muon flux at large zenith angles up to 90@xmath0 are especially actual since primary particles for such muons have higher energies than in the vertical direction . experimental studies of muon intensity at large zenith angles at the ground level can be conditionally separated in two groups : measurements of muon integral intensity with threshold energies less than 1 gev [ 1][8 ] and investigations of integral and differential muon spectra for muon energies higher than 10 gev ( see review [ 9 ] ) .. Please generate the next two sentences of the article

regions of measurements of muon spectrum at large zenith angles are presented in fig . it is remarkable that for threshold energies from 1 gev to 10 gev and zenith angles 60@xmath1 muon intensity data are absent . to explore this region

Suppose that you have an abstract for a scientific paper: the physical meaning of the levi - civita spacetime , for some critical values of the parameter @xmath0 , is discussed in the light of gedanken experiments performed with gyroscopes circumventing the axis of symmetry . the fact that @xmath1 corresponds to flat space described from the point of view of an accelerated frame of reference , led us to incorporate the c - metric into discussion . the interpretation of @xmath2 as an angle coordinate for any value of @xmath0 , appears to be at the origin of difficulties . . And you have already written the first three sentences of the full article: to provide physical meaning to solutions of einstein equations , is an endeavour whose relevance deserves to be emphasized @xcite . this is particularly true in the case of the levi - civita ( lc ) spacetime @xcite which after many years and a long list of works dedicated to its discussion still presents serious challenges to its interpretation ( @xcite , @xcite-@xcite , and references therein ) . this metric has two essential constants , usually denoted by @xmath3 and @xmath0 .. Please generate the next two sentences of the article

one of them , @xmath4 has to do with the topology of spacetime and , more specifically , refers to the deficit angle . it may accordingly be related to the gravitational analog of aharonov bohmm effect @xcite , @xcite .

Suppose that you have an abstract for a scientific paper: the reference rdbms for bessy ii has been set up with a device oriented data model . this has proven adequate for e.g. template based rtdb generation , modelling etc . but since assigned i / o channels have been stored outside the database ( a ) numerous specific conditions had to be maintained within the scripts generating configuration files and ( b ) several generic applications could not be set up automatically by scripts . in a larger re - design effort the i / o channels are introduced into the rdbms . that modification allows to generate a larger set of rtdbs , map specific conditions into database relations and maintain application configurations by relatively simple extraction scripts . . And you have already written the first three sentences of the full article: within the last few years _ relational database management systems _ ( rdbms or db in short ) have become essential for control system configuration . with availability of generic applications and hardware standards the interplay of components as well as the adaptation to site specific needs has become crucial . proper networking has been the central problem of the past .. Please generate the next two sentences of the article

today s challenge is a central repository of reference and configuration data as well as an appropriate standard suite of db applications . target is a management system providing consistency in a programmable , comprehensible and automatic way for development , test and production phases of the control system . instead of careful bookkeeping of innumerable hand - edited files

Suppose that you have an abstract for a scientific paper: new exact vacuum solutions with various singularities in the plane - symmetric spacetime are shown , and they are applied to the analysis of inhomogeneous cosmological models and colliding gravitational waves . one of the singularities can be true null singularities , whose existence was locally clarified by ori . these solutions may be interesting from the viewpoint of the variety of cosmological singularities and the instability problem of cauchy horizons inside black holes . . And you have already written the first three sentences of the full article: the important behavior of colliding gravitational waves was first shown in khan and penrose s pioneering work [ 1 ] in a plane - symmetric spacetime . the formulation for dynamics of colliding plane waves was given by szekeres [ 2 ] in an extended form with non - parallel polarization , and the solution , which is impulsive similarly to khan and penrose s one , was derived by nuktu and halil [ 3 ] . the plane - symmetric inhomogeneous cosmological models were , on the other hand , studied by gowdy [ 4 ] in a vacuum spacetime with compact invariant hypersurfaces , and models containing space - like and time - like singularities alternately were discussed by the present author [ 5 ] .. Please generate the next two sentences of the article

studies on impulsive colliding gravitational waves were developed by chandrasekhar and his collaborators [ 6 ] who treated not only vacuum cases but also the cases with fluids and electromagnetic fields , and derived also the solutions with a time - like singularity . yurtsever [ 7 ] derived solutions which tend to the kasner solutions asymptotically , contain the cauchy horizons , and are connected with the schwarzschild and weyl vacuum solutions .

Suppose that you have an abstract for a scientific paper: we examine the statics and dynamics of particles with repulsive yukawa interactions in the presence of a two - dimensional triangular substrate for fillings of up to twelve particles per potential minimum . we term the ordered states yukawa cluster crystals and show that they are distinct from the colloidal molecular crystal states found at low fillings . as a function of substrate and interaction strength at fixed particle density we find a series of novel crystalline states that we characterize using the structure factor . for fillings greater than four , shell and ring structures form at each potential minimum and can exhibit sample - wide orientational order . a disordered state can appear between ordered states as the substrate strength varies . under an external drive , the onsets of different orderings produce clear changes in the critical depinning force , including a peak effect phenomenon that has generally only previously been observed in systems with random substrates . we also find a rich variety of dynamic ordering transitions that can be observed via changes in the structure factor and features in the velocity - force curves . the dynamical states encompass a variety of moving structures including one - dimensional stripes , smectic ordering , polycrystalline states , triangular lattices , and symmetry locking states . despite the complexity of the system , we identify several generic features of the dynamical phase transitions which we map out in a series of phase diagrams . our results have implications for the structure and depinning of colloids on periodic substrates , vortices in superconductors and bose - einstein condensates , wigner crystals , and dusty plasmas . . And you have already written the first three sentences of the full article: the creation of new types of crystalline or partially ordered states and the dynamics of assemblies of interacting particles have attracted much attention both in terms of the basic science of self - assembly and dynamic pattern formation as well as for applications utilizing self - assembly processes . one of the most extensively studied systems exhibiting this behavior is assemblies of colloidal particles , where the equilibrium structures can be tuned by changing the directionality of the colloid - colloid interactions @xcite . since it can be difficult to control and tune the exact form of the interaction , another approach is to use colloids with well defined interactions that are placed on some type of ordered substrate . optical trapping techniques are one of the most common methods of creating periodic substrates for colloids @xcite . studies of colloidal ordering and melting for one dimensional ( 1d ) periodic substrate arrays have revealed ordered colloidal crystalline structures as well as smectic type structures where the colloids are crystalline in one direction and liquidlike in the other @xcite .. Please generate the next two sentences of the article

these experiments show that the substrate strength strongly influences the type of colloidal structure that forms and that as the substrate strength increases , the resulting enhancement of fluctuations can induce a transition from crystalline to smectic order @xcite . numerous different colloidal crystalline structures can also appear on 1d substrate arrays of fixed periodicity when the colloid density is varied @xcite .

Suppose that you have an abstract for a scientific paper: we measured the angular diameter of the lithium - rich k giant star hd 148293 using georgia state university s center for high angular resolution astronomy ( chara ) array interferometer . we used our measurement to calculate the star s effective temperature , which allowed us to place it on an h - r diagram to compare it with other li - rich giants . its placement supports the evidence presented by @xcite that it is undergoing a brief stage in its evolution where li is being created . . And you have already written the first three sentences of the full article: g and k giant stars are expected to have low lithium abundances because li is destroyed in main - sequence stars except in the outermost layers ( 1@xmath0 - 2@xmath0 by mass ) . as the star ascends the red giant branch of the h - r diagram , the convective envelope deepens , diluting the existing li and further reducing the observable li @xcite . this effect is seen in most g and k giant stars , though a small minority ( @xmath1 ) exist that are unexpectedly rich in li ( e.g. , * ? ? ?. Please generate the next two sentences of the article

* ; * ? ? ? * ; * ? ? ?

Suppose that you have an abstract for a scientific paper: a novel protocol , measurement - device - independent quantum key distribution ( mdi - qkd ) , removes all attacks from the detection system , the most vulnerable part in qkd implementations . in this paper , we present an analysis for practical aspects of mdi - qkd . to evaluate its performance , we study various error sources by developing a general system model . we find that mdi - qkd is highly practical and thus can be easily implemented with standard optical devices . moreover , we present a simple analytical method with only two ( general ) decoy states for the finite decoy - state analysis . this method can be used directly by experimentalists to demonstrate mdi - qkd . by combining the system model with the finite decoy - state method , we present a general framework for the optimal choice of the intensities of the signal and decoy states . furthermore , we consider a common situation , namely _ asymmetric _ mdi - qkd , in which the two quantum channels have different transmittances . we investigate its properties and discuss how to optimize its performance . our work is of interest not only to experiments demonstrating mdi - qkd but also to other non - qkd experiments involving quantum interference . . And you have already written the first three sentences of the full article: quantum key distribution ( qkd ) @xcite enables an unconditionally secure means of distributing secret keys between two spatially separated parties , alice and bob . the security of qkd has been rigorously proven based on the laws of quantum mechanics @xcite . nevertheless , owing to the imperfections in real - life implementations , a large gap between its theory and practice remains unfilled .. Please generate the next two sentences of the article

in particular , an eavesdropper ( eve ) may exploit these imperfections and launch specific attacks . this is commonly called quantum hacking . the first successful quantum hacking against a commercial qkd system was the time - shift attack @xcite based on a proposal in @xcite .

Suppose that you have an abstract for a scientific paper: we study the single site dynamics in stochastic particle systems of misanthrope type with bounded rates on a complete graph . in the limit of diverging system size we establish convergence to a markovian non - linear birth death chain , described by a mean - field equation known also from exchange - driven growth processes . conservation of mass in the particle system leads to conservation of the first moment for the limit dynamics , and to non - uniqueness of stationary measures . the proof is based on a coupling to branching processes via the graphical construction , and establishing uniqueness of the solution for the limit dynamics . as particularly interesting examples we discuss the dynamics of two models that exhibit a condensation transition and their connection to exchange - driven growth processes . * keywords . * mean - field equations , misanthrope processes , non - linear birth death chain , condensation . . And you have already written the first three sentences of the full article: in the physics literature , stochastic particle systems in a limit of large system size are often described by a mean - field master equation for the time evolution of a single lattice site @xcite . for conservative systems , these equations are very similar to mean - field rate equations in the study of cluster growth models ( see e.g. @xcite and the references therein ) . we focus on particle systems where only one particle jumps at a time , which corresponds to monomer exchange in cluster growth models as studied in @xcite , and also in the well - known becker - dring model @xcite . while these mean - field equations often provide the starting point for the analysis and have an intuitive form , to our knowledge their connection to underlying particle systems has not been rigorously established so far . in this paper. Please generate the next two sentences of the article

, we provide a rigorous derivation of this equation for misanthrope - type processes @xcite with bounded jump rates and homogeneous initial conditions on a complete graph . the limit equation describes the dynamics of the fraction @xmath0 $ ] of lattice sites with a given occupation number @xmath1 , and also provides the master equation of a birth death chain for the limiting single site dynamics of the process .

Suppose that you have an abstract for a scientific paper: in this paper , we show that the time evolution of the bloch vector governed by the thermal jaynes - cummings model is equivalent to a compressible inviscid flow with zero vorticity . because of its quasiperiodicity , the dynamics of the bloch vector includes countably infinite angular momenta as integrals of motion . moreover , to derive the bloch vector , we trace out the hilbert space of the cavity field and remove entanglement between the single atom and the cavity mode . these facts indicate that the dynamics of the bloch vector can be described with a hidden - variable model that has local determinism and a countably infinite number of degrees of freedom . our results fit these considerations . . And you have already written the first three sentences of the full article: in 1963 , the jaynes - cummings model ( jcm ) was proposed for describing interaction between a single two - state atom and a single near - resonant quantized cavity mode @xcite . considering the hamiltonian for a magnetic dipole in a magnetic field , assuming near resonance and applying the rotating - wave approximation to it , we obtain the hamiltonian of the jcm . the jcm has been attracting a lot of researchers attention in the field of the quantum optics since 1960s , because it is soluble and fully quantum mechanical .. Please generate the next two sentences of the article

one of the most remarkable properties of the jcm is a phenomenon of collapse and revival of rabi oscillations . if we put the cavity field into the coherent state initially , the jcm shows the spontaneous periodic collapse and revival of the rabi oscillations in the atomic population inversion during its time evolution .

Suppose that you have an abstract for a scientific paper: we investigate the problem of determining the parameters that describe a quantum channel . it is assumed that the users of the channel have at best only partial knowledge of it and make use of a finite amount of resources to estimate it . we discuss simple protocols for the estimation of the parameters of several classes of channels that are studied in the current literature . we define two different quantitative measures of the quality of the estimation schemes , one based on the standard deviation , the other one on the fidelity . the possibility of protocols that employ entangled particles is also considered . it turns out that the use of entangled particles as a new kind of nonclassical resource enhances the estimation quality of some classes of quantum channel . further , the investigated methods allow us to extend them to higher dimensional quantum systems . # 1|#1 # 1#1| # 1#2#1|#2 # 1#2#3#1|#2|#3 . And you have already written the first three sentences of the full article: quantum information processing has attracted a lot of interest in recent years , following deutsch s investigations @xcite concerning the potentiality of a quantum computer , i.e. , a computer where information is stored and processed in quantum systems . their application as quantum information carriers gives rise to outstanding possibilities , like secret communication ( quantum cryptography ) and the implementation of quantum networks and quantum algorithms that are more efficient than classical ones @xcite . many investigations concern the transmission of quantum information from one party ( usually called alice ) to another ( bob ) through a communication channel . in the most basic configuration. Please generate the next two sentences of the article

the information is encoded in qubits . if the qubits are perfectly protected from environmental influence , bob receives them in the same state prepared by alice . in the more realistic case , however , the qubits have a nontrivial dynamics during the transmission because of their interaction with the environment @xcite . therefore , bob receives a set of distorted qubits because of the disturbing action of the channel . up to

Suppose that you have an abstract for a scientific paper: any viable cosmological model must produce enough structure at early epochs to explain the amount of gas associated with high - redshift systems . we study the evolution of systems at redshifts @xmath0 in cold dark matter ( cdm ) and cold+hot dark matter ( cdm+hdm ) models using both @xmath1-body and hydrodynamic simulations . our approach incorporates the effects of gas dynamics , and we find that all earlier estimates which assumed that all the baryons in dark matter halos would contribute to absorption have overestimated the column density distribution @xmath2 and the fraction of neutral dense gas @xmath3 in systems . the differences are driven by ionization of hydrogen in the outskirts of galactic halos and by gaseous dissipation near the halo centers , and they tend to exacerbate the problem of late galaxy formation in cdm+hdm models . we only include systems up to the highest observed column density @xmath4 @xmath5 in the estimation of @xmath3 for a fair comparison with data . if the observed @xmath2 and @xmath3 inferred from a small number of confirmed and candidate absorbers are robust , the amount of gas in systems at high redshifts in the @xmath6 cdm+hdm model falls well below the observations . epsf.tex submitted to _ the astrophysical journal letters _ . And you have already written the first three sentences of the full article: high - redshift absorbers offer a glimpse of structure in the young universe . these systems dominate the mass density of neutral gas in the universe at early times and are believed to be forming galaxies ( wolfe et al . 1995 ; djorgovski et al . 1996 ) . the fraction @xmath3 of the present - day critical density residing in neutral gas in these objects increases monotonically with redshift to @xmath7 ( lanzetta , wolfe , & turnshek 1995 ; wolfe et al .. Please generate the next two sentences of the article

1995 ) . at still higher redshifts , @xmath8 , recent optical spectroscopy of 27 quasars indicates a decline in @xmath3 ( storrie - lombardi et al .

Suppose that you have an abstract for a scientific paper: the construction of the semiclassical trace formula for the resonances with the transverse electric ( te ) polarization for two - dimensional dielectric cavities is discussed . special attention is given to the derivation of the two first terms of weyl s series for the average number of such resonances . the obtained formulas agree well with numerical calculations for dielectric cavities of different shapes . . And you have already written the first three sentences of the full article: open dielectric cavities have attracted a large interest in recent years due to their numerous and potentially important applications @xcite . from a theoretical point of view , the crucial difference between dielectric cavities and much more investigated case of closed quantum billiards @xcite is that in the latter the spectrum is discrete but in the former it is continuous . indeed , the main subject of investigations in open systems is not the true spectrum but the spectrum of resonances defined as poles of the scattering @xmath0-matrix ( see e.g. @xcite ) .. Please generate the next two sentences of the article

the wavelength of electromagnetic field is usually much smaller than any characteristic cavity size ( except its height ) and semiclassical techniques are useful and adequate for a theoretical approach to such objects . it is well known that the trace formulas are a very powerful tool in the semiclassical description of closed systems , see e.g. @xcite . therefore , the generalization of trace formulas to different open systems , in particular to dielectric cavities , is of importance .

Suppose that you have an abstract for a scientific paper: the production of all identified hadrons at the cern large hadron collider ( lhc ) is studied with emphasis on the @xmath0 distributions up to 20 gev / c in central collisions . in the framework of the recombination model we find that the shower partons ( due to the fragmentation of semihard partons ) play an important role in the formation of hadrons in the low- and intermediate-@xmath0 regions . parameters that control the energy loss of minijets are determined by fitting the upper half of the @xmath0 range of the pion distribution . the resultant soft shower partons are then found to dominate over the thermal partons in the non - strange sector , but not in the strange sector . since the data on the @xmath0 spectra of all observed hadrons are well reproduced , there is no way out of the implication that any alternative dynamical model on particle production would be incomplete if it does not consider the effects of minijets even at very low @xmath0 . hydrodynamics that relies on rapid equilibration without accounting for the delayed thermalization effects of the hard and semihard partons copiously produced at lhc is an example of such models . the difference between the densities of shower partons produced at lhc and at bnl relativistic heavy - ion collider ( rhic ) is quantified and discussed . . And you have already written the first three sentences of the full article: theoretical investigation of hadron production in heavy - ion collisions at high energies is usually separated into different camps , characterized by the regions of transverse momenta @xmath0 of the produced hadrons . at low @xmath0 statistical hadronization and hydrodynamical models are generally used @xcite , whereas at high @xmath0 jet production and parton fragmentation with suitable consideration of medium effects in perturbative qcd are the central themes @xcite . the two approaches have been studied essentially independent of each other with credible success in interpreting the data , since their dynamics are decoupled at the energies investigated .. Please generate the next two sentences of the article

the situation may have changed at the cern large hadron collider ( lhc ) , where pb - pb collisions have been carried out at @xmath1 tev , resulting in thousands of soft hadrons on the one hand , and multiple hard jets on the other . minijets that are copiously produced at intermediate @xmath0 can fragment into soft partons with multiplicities so high that their effects on the hadronization of all partons created in the soft sector can not be ignored .

Suppose that you have an abstract for a scientific paper: we present the first detection of n@xmath0h@xmath1 towards a low - mass protostellar outflow , namely the l1157-b1 shock , at @xmath2 0.1 pc from the protostellar cocoon . the detection was obtained with the iram 30-m antenna . we observed emission at 93 ghz due to the @xmath3 = 10 hyperfine lines . the analysis of the emission coupled with the hifi chess multiline co observations leads to the conclusion that the observed n@xmath0h@xmath1(10 ) line originates from the dense ( @xmath4 10@xmath5 @xmath6 ) gas associated with the large ( 20@xmath725@xmath7 ) cavities opened by the protostellar wind . we find a n@xmath0h@xmath1 column density of few 10@xmath8 @xmath9 corresponding to an abundance of ( 28 ) @xmath10 10@xmath11 . the n@xmath0h@xmath1 abundance can be matched by a model of quiescent gas evolved for more than 10@xmath12 yr , i.e. for more than the shock kinematical age ( @xmath13 2000 yr ) . modelling of c - shocks confirms that the abundance of n@xmath0h@xmath1 is not increased by the passage of the shock . in summary , n@xmath0h@xmath1 is a fossil record of the pre - shock gas , formed when the density of the gas was around 10@xmath12 @xmath6 , and then further compressed and accelerated by the shock . . And you have already written the first three sentences of the full article: during the first stages of star formation , highly collimated jets from new born stars influence the physical structure of the hosting cloud by sweeping up material , compressing and accelerating the surrounding environment . the propagation of high velocity outflows generates shock fronts triggering endothermic chemical reactions and ice grain mantle sublimation or sputtering . at a distance of 250 pc ( looney et al . 2007 ) , the chemically rich l1157 bipolar outflow ( bachiller & prez gutirrez 1997 , hereafter bp97 , bachiller et al .. Please generate the next two sentences of the article

2001 ) is an ideal laboratory to observe the effects of such shocks on the gas chemistry . l1157 is driven by a low - mass ( @xmath2 4 @xmath14 ) class 0 protostar l1157-mm and it is associated with several blue - shifted ( b0 , b1 , b2 ) and red - shifted ( r0 , r1 , r2 ) shocks at different ages ( see fig . [ maps]top panel ) , and seen in both co ( gueth et al .

Suppose that you have an abstract for a scientific paper: basis set convergence of the hartree - fock and the correlation energy is examined for the hydrogen bonded _ infinite _ bent chains ( hf)@xmath0 and ( hcl)@xmath0 . we employ series of correlation consistent basis sets up to quintuple @xmath1 quality together with a coupled cluster method ( ccsd ) to describe electron correlation on _ ab initio _ level . the hartree - fock energy converges rapidly with increasing basis set quality whereas the correlation energy is found to be slowly convergent for the same series of basis sets . we study basis set extrapolation for ( hf)@xmath0 and ( hcl)@xmath0 and show that it substantially enhances the accuracy of both the hartree - fock and the correlation energy in _ extended _ systems . , electron correlation , ab initio calculations , hydrogen fluoride , hydrogen chloride , infinite bent chains , basis set convergence , basis set extrapolation 31.15.ar , 31.25.qm , 71.15.nc , 71.20.ps . And you have already written the first three sentences of the full article: _ ab initio _ methods for polymers and crystals come more and more into focus of quantum chemists and solid state physicists @xcite . as most _ ab initio _ treatments of such extended systems rely on incomplete one - particle basis sets , we consider it timely to investigate the basis set convergence of hartree - fock and correlation energies in _ periodic _ systems . _ molecular _ hartree - fock energies are well known to converge exponentially , e.g. ref .. Please generate the next two sentences of the article

@xcite , towards the basis set limit , but molecular correlation energies turn out to converge only with the third power of the highest angular momentum employed in the basis sets @xcite . the convergence properties of the hartree - fock and the correlation energy can be exploited to extrapolate hartree - fock @xcite and correlation energies @xcite towards the basis set limit . as only standard methods of quantum chemistry

Suppose that you have an abstract for a scientific paper: an established phenomenology and theoretical interpretation of @xmath0-@xmath0 collision data at lower collision energies should provide a reference for @xmath0-@xmath0 and other collision systems at higher energies , against which claims of novel physics may be tested . the description of @xmath0-@xmath0 collisions at the relativistic heavy ion collider ( rhic ) has remained incomplete even as claims for collectivity and other novelties in data from smaller systems at the large hadron collider ( lhc ) have emerged recently . in this study we report the charge - multiplicity dependence of two - dimensional ( 2d ) angular correlations and of single - particle ( sp ) densities on transverse rapidity @xmath1 and pseudorapidity @xmath2 from 200 gev @xmath0-@xmath0 collisions . we define a comprehensive and self - consistent two - component ( soft + hard ) model ( tcm ) for hadron production and report a significant @xmath0-@xmath0 nonjet ( nj ) quadrupole component as a third ( angular - correlation ) component . our results have implications for @xmath0-@xmath0 centrality , the underlying event ( ue ) , collectivity in small systems and the existence of flows in high - energy nuclear collisions . . And you have already written the first three sentences of the full article: the hadronic final state of collisions at 200 gev may provide a reference for other high - energy nuclear collisions at the relativistic heavy ion collider ( rhic ) and large hadron collider ( lhc ) . claims for novel physics at higher energies or in , or collision systems should be based on an accurate and self - consistent phenomenology for conventional processes at 200 gev . however , current theoretical and experimental descriptions of high - energy collisions appear to be incomplete . several unresolved aspects of collisions are notable : ( a ) the role of collision centrality in relation to the low-@xmath3 gluon transverse structure of the proton @xcite , ( b ) the nature and systematics of the _ underlying event _ ( ue ) defined as complementary to contributions from an event - wise - triggered high - energy dijet @xcite , ( c ) the systematics of _ minimum - bias _. Please generate the next two sentences of the article

( mb ) dijet ( minijet ) production manifested in spectra and angular correlations @xcite and ( d ) possible existence and phenomenology of a _ nonjet azimuth quadrupole _ component in 2d angular correlations previously studied in collisions ( as quantity @xmath4 ) @xcite , especially in connection with a claimed same - side ridge observed in lhc angular correlations @xcite . a more detailed discussion of those issues is presented in sec .

Suppose that you have an abstract for a scientific paper: it is shown how any lindbladian evolution with selfadjoint lindblad operators , either markovian or nonmarkovian , can be understood as an averaged random unitary evolution . both mathematical and physical consequences are analyzed . first a simple and fast method to solve this kind of master equations is suggested and particularly illustrated with the phase - damped master equation for the multiphoton resonant jaynes - cummings model in the rotating - wave approximation . a generalization to some intrinsic decoherence models present in the literature is included . under the same philosophy a proposal to generalize the jaynes - cummings model is suggested whose predictions are in accordance with experimental results in cavity qed and in ion traps . a comparison with stochastic dynamical collapse models is also included . . And you have already written the first three sentences of the full article: since the early years of quantum mechanics @xcite the principle of quantum superposition has been recognized to play a prominent role in the theory and its applications . the destruction and preservation of these superpositions of quantum states occupy a central place in issues such as the quantum - to - classical transition @xcite and potential technological applications in quantum information , computation and cryptography @xcite . from a physical standpoint the loss of coherence in quantum systems is rooted on the pervasive action of the environment upon the system .. Please generate the next two sentences of the article

this environmental action has received a careful mathematical treatment ( cf . @xcite and multiple references therein ) going from a constructive approach based on disregarding the degrees of freedom of the environment due to their lack of control by the experimenter ( `` tracing - out '' methods ) to an axiomatic approach based on the initial setting of physically motivated axioms to derive an appropiate evolution ( master ) equation for the system @xcite .

Suppose that you have an abstract for a scientific paper: we study the andreev edge states with different pairing symmetries and boundary topologies on semi - infinite triangular lattice of na@xmath0coo@xmath1@xmath2h@xmath1o . a general mapping from the two dimensional lattice to the one dimensional tight - binding model is developed . it is shown that the phase diagram of the andreev edge states depends on the pairing symmetry and also the boundary topology . surprisingly , the structure of the phase diagram crucially relies on the nodal points on the fermi surface and can be explained by an elegant gauge argument . we compute the momentum - resolved local density of states near the edge and predict the hot spots which are measurable in fourier - transformed scanning tunneling spectroscopy . . And you have already written the first three sentences of the full article: the recent discovery of superconductivity in sodium cobalt oxide compound intercalated water molecules , na@xmath0coo@xmath1@xmath2h@xmath1o,@xcite trigged intense attentions and stimulated lots of discussions@xcite . the superconductivity induced in the planer structure of coo@xmath1 is similar with that in the cuo@xmath1 plane of cuprates@xcite . however , the underlaying triangular lattice of the co atoms is fundamentally different from the square lattice of the cu atoms in cuprates because the antiferromagnetic interactions on the triangular lattice are frustrated .. Please generate the next two sentences of the article

the carrier density in the sodium cobalt oxide can be tuned by the na concentration . by changing the sodium doping , a rich phase diagram appears and the superconductivity occurs@xcite in the doping regime @xmath3 .

Suppose that you have an abstract for a scientific paper: we determine the transfer functions of two kinds of filters that can be used in the detection of continuous gravitational radiation . the first one optimizes the signal - to - noise ratio , and the second reproduces the wave with minimum error . we analyse the behaviour of these filters in connection with actual detection schemes . . And you have already written the first three sentences of the full article: the detection of gravitational waves ( g.w . ) is one of the most fascinating and challenging subjects in physics research nowadays . besides checking the general relativity theory , the detection of this phenomenon will mark the beginning of a new phase in the comprehension of astrophysical phenomena by the use of gravitational wave astronomy . although these waves were predicted at the beginning of the century @xcite , the research on their detection only started around 1960 , with the studies of joseph weber @xcite . the major obstacle to this detection is the tiny amplitude the g.w .. Please generate the next two sentences of the article

have @xcite . even though the more sensitive detector now operating @xcite is capable to detect amplitudes near @xmath0 , this value must be decreased by several orders of magnitude so that impulsive waves can be detected regularly . on the other hand ,

Suppose that you have an abstract for a scientific paper: a simple effective model for a description of magnetically ordered insulators is analysed . the tight binding hamiltonian consists of the effective on - site interaction ( @xmath0 ) and intersite magnetic exchange interactions ( @xmath1 , @xmath2 ) between nearest - neighbours . the phase diagrams of this model have been determined within the variational approach , which treats the on - site interaction term exactly and the intersite interactions within the mean - field approximation . we show that , depending on the values of interaction parameters and the electron concentration , the system can exhibit not only homogeneous phases : ( anti-)ferromagnetic ( f@xmath3 ) and nonordered ( no ) , but also phase separated states ( ps@xmath3 : ) . . And you have already written the first three sentences of the full article: the extended hubbard model with anisotropic spin exchange interactions @xcite is a conceptually simple phenomenological model for studying correlations and for a description of magnetism and other types of electron orderings in narrow band systems with easy - plane or easy - axis magnetic anisotropy . in this report we will focus on the zero - bandwidth limit of the extended hubbard model with magnetic interactions for the case of arbitrary electron density . we consider the @xmath0-@xmath1 hamiltonian of the following form : @xmath4 where @xmath0 is the on - site density interaction , @xmath5 is @xmath6-component of the intersite magnetic exchange interaction , restricts the summation to nearest neighbours .. Please generate the next two sentences of the article

@xmath7 denotes the creation operator of an electron with spin @xmath8 at the site @xmath9 , , and . the chemical potential @xmath10 depending on the concentration of electrons is calculated from @xmath11 with and @xmath12 is the total number of lattice sites . the model ( [ row:1 ] ) can be treated as an effective model of magnetically ordered insulators . the interactions @xmath0 and @xmath1 will be assumed to include all the possible contributions and renormalizations like those coming from the strong electron - phonon coupling or from the coupling between electrons and other electronic subsystems in solid or chemical complexes . in such a general case

Suppose that you have an abstract for a scientific paper: we have analyzed numerically the localization length of light @xmath0 for nearly periodic arrangements of homogeneous stacks ( formed exclusively by right - handed materials ) and mixed stacks ( with alternating right and left - handed metamaterials ) . layers with index of refraction @xmath1 and thickness @xmath2 alternate with layers of index of refraction @xmath3 and thickness @xmath4 . positional disorder has been considered by shifting randomly the positions of the layer boundaries with respect to periodic values . for homogeneous stacks , we have shown that the localization length is modulated by the corresponding bands and that @xmath0 is enhanced at the center of each allowed band . in the limit of long - wavelengths @xmath5 , the parabolic behavior previously found in purely disordered systems is recovered , whereas for @xmath6 a saturation is reached . in the case of nearly periodic mixed stacks with the condition @xmath7 , instead of bands there is a periodic arrangement of lorenztian resonances , which again reflects itself in the behavior of the localization length . for wavelengths of several orders of magnitude greater than @xmath8 , the localization length @xmath0 depends linearly on @xmath5 with a slope inversely proportional to the modulus of the reflection amplitude between alternating layers . when the condition @xmath9 is no longer satisfied , the transmission spectrum is very irregular and this considerably affects the localization length . . And you have already written the first three sentences of the full article: during the last decades , a new type of artificial materials , the so - called left - handed metamaterials ( lh ) , have attracted a great deal of attention . they present negative indices of refraction for some wavelengths @xcite , with considerable applications in modern optics and microelectronics @xcite . metamaterials can resolve images beyond the diffraction limit @xcite , act as an electromagnetic cloak @xcite , enhance the quantum interference @xcite or yield to slow light propagation @xcite .. Please generate the next two sentences of the article

regarding the localization length in disordered systems , the presence of negative refraction in one - dimensional ( 1d ) disordered metamaterials strongly suppresses anderson localization @xcite . as a consequence , an unusual behavior of the localization length @xmath0 at long - wavelengths @xmath5 has been observed .

Suppose that you have an abstract for a scientific paper: motivated by the physical relevance of a spectral singularity of interacting many - particle system , we explore the dynamics of two bosons as well as fermions in one - dimensional system with imaginary delta interaction strength . based on the exact solution , it shows that the two - particle collision leads to amplitude - reduction of the wave function . for fermion pair , the amplitude - reduction depends on the spin configuration of two particles . in both cases , the residual amplitude can vanish when the relative group velocity of two single - particle gaussian wave packets with equal width reaches the magnitude of the interaction strength , exhibiting complete particle - pair annihilation at the spectral singularity . . And you have already written the first three sentences of the full article: non - hermitian operator has been introduced phenomenologically as an effective hamiltonian to fit experimental data in various fields of physics @xcite . in spite of the important role played non - hermitian operator in different branches of physics , it has not been paid due attention by the physics community until the discovery of non - hermitian hamiltonians with parity - time symmetry , which have a real spectrum @xcite . it has boosted the research on the complex extension of quantum mechanics on a fundamental level ann , jmp1,jpa1,jpa2,prl1,jmp2,jmp3,jmp4,jpa3,jpa4,jpa5 .. Please generate the next two sentences of the article

non - hermitian hamiltonian can possess peculiar feature that has no hermitian counterpart . a typical one is the spectral singularity ( or exceptional point for finite system ) , which is a mathematic concept .

Suppose that you have an abstract for a scientific paper: stellar feedback is often cited as the biggest uncertainty in galaxy formation models today . this uncertainty stems from a dearth of observational constraints as well as the great dynamic range between the small scales ( @xmath01 pc ) where the feedback originates and the large scales of galaxies ( @xmath11 kpc ) that are shaped by this feedback . to bridge this divide , in this paper we aim to assess observationally the role of stellar feedback at the intermediate scales of h ii regions ( @xmath210100 pc ) . in particular , we employ multiwavelength data to examine several stellar feedback mechanisms in a sample of 32 h ii regions ( with ages @xmath2310 myr ) in the large and small magellanic clouds ( lmc and smc , respectively ) . using optical , infrared , radio , and x - ray images , we measure the pressures exerted on the shells from the direct stellar radiation , the dust - processed radiation , the warm ionized gas , and the hot x - ray emitting gas . we find that the warm ionized gas dominates over the other terms in all of the sources , although two have comparable dust - processed radiation pressures to their warm gas pressures . the hot gas pressures are comparatively weak , while the direct radiation pressures are 12 orders of magnitude below the other terms . we discuss the implications of these results , particularly highlighting evidence for hot gas leakage from the h ii shells and regarding the momentum deposition from the dust - processed radiation to the warm gas . furthermore , we emphasize that similar observational work should be done on very young h ii regions to test whether direct radiation pressure and hot gas can drive the dynamics at early times . . And you have already written the first three sentences of the full article: stellar feedback the injection of energy and momentum by stars originates at the small scales of star clusters ( @xmath01 pc ) , yet it shapes the interstellar medium ( ism ) on large scales ( @xmath11 kpc ) . at large scales , stellar feedback is necessary in order to form realistic galaxies in simulations and to account for observed galaxy properties . in the absence of feedback. Please generate the next two sentences of the article

, baryonic matter cools rapidly and efficiently forms stars , producing an order of magnitude too much stellar mass and consuming most available gas in the galaxy ( e.g. , @xcite ) . stellar feedback prevents this `` cooling catastrophe '' by heating gas as well as removing low angular momentum baryons from galactic centers , thereby allowing only a small fraction of the baryonic budget of dark matter halos to be converted to stars .

Suppose that you have an abstract for a scientific paper: we propose to use a quantized version of coherent two - color photoassociation to realize a hybrid device for quantum control of light . the dynamical features of this system are exhibited , including the slowing down or storage of light and the molecular matter - wave solitons . this may indicate a hybrid atom - molecule quantum device for storage and retrieve of optical information . . And you have already written the first three sentences of the full article: the experimental realization of bose - einstein condensates ( becs ) in ultracold atomic gases has led to tremendous advances from traditional atomic , molecular , and optical ( amo ) physics @xcite to current quantum information science @xcite . recently , an intriguing atom - molecule dark state was observed in coherent two - color photoassociation ( pa ) @xcite , which has been considered as an efficient way to achieve higher production rates of molecules @xcite from ultracold atoms . in view of their internal properties and long - range anisotropic interactions @xcite , the assembly of heteronuclear molecules @xcite have also been actively pursued with various important applications @xcite , such as a polar molecular quantum computer @xcite . in the light of these developments it is timely to investigate the method of encoding and manipulating quantum optical state through the atom - molecule dark state .. Please generate the next two sentences of the article

such processes will provide new insights on current efforts of optical pa or quantum superchemistry with the goal of designing a hybrid atom - molecule device for quantum control of photonic information . in this work we study such a scenario by transferring the quantum state of an associating light to an atom - heternuclear molecule dark state @xcite .

Suppose that you have an abstract for a scientific paper: the problem of how single central " spins interact with a nuclear spin bath is essential for understanding decoherence and relaxation in many quantum systems , yet is highly nontrivial owing to the many - body couplings involved . different models yield widely varying timescales and dynamical responses ( exponential , power - law , gaussian , etc ) . here we detect the small random fluctuations of central spins in thermal equilibrium ( holes in singly - charged ( in , ga)as quantum dots ) to reveal the timescales and functional form of bath - induced spin relaxation . this spin noise indicates long ( 400 ns ) spin correlation times at zero magnetic field , that increase to @xmath05 @xmath1s as hole - nuclear coupling is suppressed with small ( 100 g ) applied fields . concomitantly , the noise lineshape evolves from lorentzian to power - law , indicating a crossover from exponential to inverse - log dynamics . single electron or hole central " spins confined in iii - v semiconductor quantum dots ( qds ) are promising candidates for solid - state qubits @xcite . although confinement suppresses momentum - dependent spin relaxation pathways , it enhances the hyperfine coupling between the central spin and the dense spin bath of @xmath010@xmath2 lattice nuclei comprising the qd . these hyperfine interactions dominate decoherence and spin relaxation at low temperatures . within a qd ensemble , each central spin feels a different effective ( overhauser ) magnetic field from nuclei , @xmath3 . trivially , this leads to rapid nanosecond - timescale ensemble dephasing of an initially - oriented ensemble of central spins @xcite . on longer timescales , however , decoherence and relaxation of the central spin within _ each _ qd occurs because @xmath3 evolves slowly in time @xcite . in large applied magnetic fields @xmath4 , the huge difference between electronic and nuclear zeeman energies suppresses flip - flop interactions between the two species , and @xmath3 evolves primarily via weak.... And you have already written the first three sentences of the full article: * quantum dot structures . * inas / gaas qds are grown by molecular - beam epitaxy on ( 001 ) gaas substrates , and then thermally annealed at 940 @xmath30c @xcite . annealing interdiffuses indium and gallium , resulting in ( in , ga)as / gaas qds with effective localization volumes of order 2000 nm@xmath31 , giving @xmath010@xmath2 nuclei within the spatial extent of the resident hole s wavefunction .. Please generate the next two sentences of the article

the sample contains 20 layers of qds , separated by 60 nm gaas barriers . each layer contains @xmath0@xmath32 qds/@xmath33 . although not intentionally doped , these qds are weakly _ p_-type due to background carbon doping ; we estimate that @xmath010% of the qds contain a single resident hole .

Suppose that you have an abstract for a scientific paper: controlled generation of entangled states of two quantum bits is a fundamental step toward the implementation of a quantum information processor . in nano - devices this operation is counteracted by the solid - state environment , characterized by broadband and non - monotonic power spectrum often @xmath0 at low frequencies . for single qubit gates , incoherent processes due to fluctuations acting on different time scales result in peculiar short- and long - time behaviors . markovian noise originates exponential decay with relaxation and decoherence times , @xmath1 and @xmath2 , simply related to the symmetry of the qubit - environment coupling hamiltonian . noise with @xmath0 power spectrum at low frequencies is instead responsible for defocusing processes and algebraic short - times behavior . in this article we identify the relevant decoherence times of an entangling operation due to the different decoherence channels originated from solid state noise . entanglement is quantified by the concurrence , which we evaluate in analytic form employing a multi - stage approach . `` optimal '' operating conditions of reduced sensitivity to noise sources are identified . we apply this analysis to a superconducting @xmath3 gate for experimental noise spectra . . And you have already written the first three sentences of the full article: the implementation of a universal two - qubit gate involving an entanglement operation on two quantum bits represents a necessary step toward the construction of a scalable quantum computer @xcite . intense research on solid state nano - devices during the last decade has established the possibility to combine quantum coherent behavior with the existing integrated - circuit fabrication technology . in particular , based on superconducting technologies , a variety of high - fidelity single qubit gates are nowadays available @xcite , two - qubit logic gates @xcite and violations of bell s inequalities @xcite have been demonstrated , high - fidelity bell states generated @xcite . the recent demonstrations of simple quantum algorithms @xcite and three - qubit entanglement @xcite are further important steps toward a practical quantum computation with superconducting circuits .. Please generate the next two sentences of the article

the requirements for building an elementary quantum processor are however quite demanding on the efficiency of the protocols . this includes both a severe constraint on readout and a sufficient isolation from fluctuations to reduce decoherence effects .

Suppose that you have an abstract for a scientific paper: global transposable characteristics in the complete dna sequence of the saccharomyces cevevisiae yeast is determined by using the metric representation and recurrence plot methods . in the form of the correlation distance of nucleotide strings , 16 chromosome sequences of the yeast , which are divided into 5 groups , display 4 kinds of the fundamental transposable characteristics : a short period increasing , a long quasi - period increasing , a long major value and hardly relevant . * keywords * yeast , dna sequences , coherence structure , metric representation , recurrence plot + . And you have already written the first three sentences of the full article: the recent complete dna sequences of many organisms are available to systematically search of genome structure . for the large amount of dna sequences , developing methods for extracting meaningful information is a major challenge for bioinformatics . to understand the one - dimensional symbolic sequences composed of the four letters ` a ' , ` c ' , ` g ' and ` t ' ( or ` u ' ) , some statistical and geometrical methods were developed@xcite . in special , chaos game representation ( cgr)@xcite , which generates a two - dimensional square from a one - dimensional sequence , provides a technique to visualize the composition of dna sequences . the characteristics of cgr images was described as genomic signature , and classification of species in the whole bacteria genome was analyzed by making an euclidean metric between two cgr images@xcite . based on the genomic signature ,. Please generate the next two sentences of the article

the distance between two dna sequences depending on the length of nucleotide strings was presented@xcite and the horizontal transfers in prokaryotes and eukaryotes were detected and charaterized@xcite . recently , a one - to - one metric representation of the dna sequences@xcite , which was borrowed from the symbolic dynamics , makes an ordering of subsequences in a plane .

Suppose that you have an abstract for a scientific paper: pour lastrophysicien qui aborde le puzzle de la matire noire , celle - ci apparat sous deux aspects diffrents : dune part en cosmologie , cest - - dire trs grandes chelles , o elle semble tre forme dun bain de particules , et dautre part lchelle des galaxies , o elle est dcrite par un ensemble de phnomnes trs particuliers , qui paraissent incompatibles avec sa description en termes de particules , et qui font dire certains que lon est en prsence dune modification de la loi de la gravitation . rconcilier ces deux aspects distincts de la matire noire dans un mme formalisme thorique reprsente un dfi important qui pourrait peut - tre conduire une physique nouvelle en action aux chelles astronomiques . . And you have already written the first three sentences of the full article: dans le modle cosmologique , dit de concordance car il est en conformit avec tout un ensemble de donnes observationnelles , la matire ordinaire do nt sont constitus les toiles , le gaz , les galaxies , etc . ( essentiellement sous forme baryonique ) ne forme que 4% de la masse - nergie totale , ce qui est dduit de la nuclosynthse primordiale des lments lgers , ainsi que des mesures de fluctuations du rayonnement du fond diffus cosmologique ( cmb ) le rayonnement fossile qui date de la formation des premiers atomes neutres dans lunivers . nous savons aussi quil y a 23% de matire noire sous forme _. Please generate the next two sentences of the article

non baryonique _ et do nt nous ne connaissons pas la nature . et les 73% qui restent ?

Suppose that you have an abstract for a scientific paper: we present results from the photometric and spectroscopic identification of 122 x - ray sources recently discovered by xmm - newton in the 2 - 10 kev band ( the hellas2xmm 1df sample ) . one of the most interesting results ( which is found also in deeper sourveys ) is that @xmath0 of the sources have an x - ray to optical flux ratio ( x / o ) ten times or more higher than that of optically selected agn . unlike the faint sources found in the ultra - deep chandra and xmm - newton surveys , which reach x - ray ( and optical ) fluxes @xmath1 times lower than in the hellas2xmm sample , many of the extreme x / o sources in our sample have r@xmath2 and are therefore accessible to optical spectroscopy . we report the identification of 13 sources with extreme x / o values . while four of these sources are broad line qso , eight of them are narrow line qso , seemingly the extension to very high luminosity of the type 2 seyfert galaxies . x - ray : background , x - ray : surveys , qso : evolution . And you have already written the first three sentences of the full article: hard x - ray surveys are the most direct probe of supermassive black hole ( smbh ) accretion activity , which is recorded in the cosmic x - ray background ( cxb ) , in wide ranges of smbh masses , down to @xmath3 , and bolometric luminosities , down to @xmath4 erg / s . x - ray surveys can therefore be used to : study the evolution of the accreting sources ; measure the smbh mass density ; constrain models for the cxb @xcite , and models for the formation and evolution of the structure in the universe @xcite . these studies have so far confirmed , at least qualitatively , the predictions of standard agn synthesis models for the cxb : the 2 - 10 kev cxb is mostly made by the superposition of obscured and unobscured agns ( @xcite and references therein ) .. Please generate the next two sentences of the article

quantitatively , though , rather surprising results are emerging : a rather narrow peak in the range z=0.7 - 1 is present in the redshift distributions from ultra - deep chandra and xmm - newton pencil - beam surveys , in contrast to the broader maximum observed in previous shallower soft x - ray surveys made by rosat , and predicted by the above mentioned synthesis models . however , the optical identification of the faint sources in these ultra - deep surveys is rather incomplete , especially for the sources with very faint optical counterparts , i.e. sources with high x - ray to optical flux ratio ( x / o ) .

Suppose that you have an abstract for a scientific paper: we study numerically the effect of sequence heterogeneity on the thermodynamic properties of a poland - scheraga model for dna denaturation taking into account self - avoidance , _ i.e. _ with exponent @xmath0 for the loop length probability distribution . in complement to previous on - lattice monte carlo like studies , we consider here off - lattice numerical calculations for large sequence lengths , relying on efficient algorithmic methods . we investigate finite size effects with the definition of an appropriate _ intrinsic _ length scale @xmath1 , depending on the parameters of the model . based on the occurrence of large enough _ rare regions _ , for a given sequence length @xmath2 , this study provides a qualitative picture for the finite size behavior , suggesting that the effect of disorder could be sensed only with sequence lengths diverging exponentially with @xmath1 . we further look in detail at average quantities for the particular case @xmath3 , ensuring through this parameter choice the correspondence between the off - lattice and the on - lattice studies . taken together , the various results can be cast in a coherent picture with a crossover between a nearly _ pure system like _ behavior for small sizes @xmath4 , as observed in the on - lattice simulations , and the apparent asymptotic behavior indicative of disorder relevance , with an ( average ) correlation length exponent @xmath5 . \a ) _ ceres - erti ( plateforme environnement ) _ , + ecole normale suprieure , 24 rue lhomond , 75005 paris b)_unit de bio - informatique structurale _ , + institut pasteur , 25 - 28 rue du docteur roux , 75724 paris cedex 15 + pacs : 64.60.fr equilibrium properties near critical points , critical exponents + pacs : 82.39.pj nucleic acids , dna and rna bases + pacs : 02.60.cb numerical simulation , solution of equations . And you have already written the first three sentences of the full article: the discovery of the dna double - helical structure , some 50 years ago , motivated the elaboration of the helix - coil model to account for the separation of the two strands , on physical bases @xcite . the importance of this model from the biological point of view is obvious , since processing of the genetic information involves precisely the separation of the strands . of course , under physiological conditions , the opening of the double - helix is not under the effect of temperature , but the differential stabilities in dna sequences , as revealed by helix - coil analysis , could be sensed by biological effectors , such as proteins , under various types of constraints . the successful development of the helix - coil denaturation model required appropriate elaborations for the physics and the algorithmics , allowing accurate tests through comparisons with experimental data ( melting curves ) .. Please generate the next two sentences of the article

this field , very active in the sixties and seventies , has benefited recently from a renewed interest both from the biological side , for example in the context of genomic analysis , and from the physics side , notably in relation with questions relevant to the order of the transition in the homogeneous case and the effect of sequence heterogeneity . in the light of these still debated issues , both from the theoretical and the numerical points of view , the main focus of the present work is the numerical investigation of the relevance of disorder in a realistic dna denaturation model _ la _ poland - scheraga , in which self - avoidance between loops and the rest of the chain is also taken into account . in what follows , before further detailing the particular system considered and the open questions , we first recall briefly the general background in terms of biological models , numerical methods and previous results . _

Suppose that you have an abstract for a scientific paper: i constrain a possible supernova origin for gamma - ray bursts by modeling the dynamical interaction between a relativistic jet and a stellar envelope surrounding it . the delay in observer s time introduced by the jet traversing the envelope should not be long compared to the duration of gamma - ray emission ; also , the jet should not be swallowed by a spherical explosion it powers . the only stellar progenitors that comfortably satisfy these constraints , if one assumes that jets move ballistically within their host stars , are compact carbon - oxygen or helium post - wolf - rayet stars ( type ic or ib supernovae ) ; type ii supernovae are ruled out . notably , very massive stars do not appear capable of producing the observed bursts at any redshift unless the stellar envelope is stripped prior to collapse . the presence of a dense stellar wind places an upper limit on the lorentz factor of the jet in the internal shock model ; however , this constraint may be evaded if the wind is swept forward by a photon precursor . shock breakout and cocoon blowout are considered individually ; neither presents a likely source of precursors for cosmological grbs . these envelope constraints could conceivably be circumvented if jets are laterally pressure - confined while traversing the outer stellar envelope . if so , jets responsible for observed grbs must either have been launched from a region several hundred kilometers wide , or have mixed with envelope material as they travel . a phase of pressure confinement and mixing would imprint correlations among jets that may explain observed grb variability - luminosity and lag - luminosity correlations . [ firstpage ] gamma rays : bursts , supernovae : general , shock waves , relativity . And you have already written the first three sentences of the full article: there is presently a growing body of circumstantial evidence linking some long - duration gamma ray bursts ( grbs ) with afterglows to the explosions of massive stars . supernovae ( sn ) or supernova - like features have been identified in seven afterglows although some of these could be light echoes from dust clouds @xcite . the afterglows of six other grbs have been interpreted in terms of a wind - like ambient medium as expected around a massive star at the end of its life .. Please generate the next two sentences of the article

however these are often equally well explained by a collimated flow in a uniform medium . x - ray lines have been detected with moderate confidence in about half the afterglows for which they were investigated @xcite ; however , the data analysis has been questioned ( see * ? ? ?

Suppose that you have an abstract for a scientific paper: double parton scattering ( dps ) is studied at the example of @xmath0 pair - production in the lhcb and atlas experiments of the large hadron collider ( lhc ) at centre - of - mass energies of @xmath1 , 8 , and 13 tev . we report theoretical predictions delivered to the lhcb and atlas collaborations adjusted for the fiducial volumes of the corresponding measurements during run i and provide new predictions at 13 tev collision energy . it is shown that dps can lead to noticeable contributions in the distributions of longitudinal variables of the di-@xmath0 system , especially at 13 tev . the increased dps rate in double @xmath0 production at high energies will open up more possibilities for the separation of single parton scattering ( sps ) and dps contributions in future studies . ms - tp-16 - 21 * double parton scattering in pair - production of @xmath0 mesons at the lhc revisited * + christoph borschensky@xmath2 and anna kulesza@xmath3 _ @xmath4 institute for theoretical physics , university of tbingen , auf der morgenstelle 14 , d-72076 tbingen , germany + @xmath5 institute for theoretical physics , wwu mnster , d-48149 mnster , germany _ . And you have already written the first three sentences of the full article: the large hadron collider ( lhc ) probes collisions of protons at very high energies , resulting in a multitude of final - state particles . with increasing energy , the probability that one hadron - hadron collision leads to more than one scattering process also increases . these additional scattering processes beside the primary hard scattering belong to the group of multi - parton interactions ( mpi ) . their estimation is important for the correct determination of background from standard model processes , for instance when the signal process consists of new physics particles .. Please generate the next two sentences of the article

in particular , double parton scattering ( dps ) , where two distinct parton interactions arise from the same proton - proton collision , can become likely enough to compete with single parton scattering ( sps ) processes , see fig . [ fig : dpsfeyn ] .

Suppose that you have an abstract for a scientific paper: few - body systems , such as cold atoms and halo nuclei , share universal features at low energies , which are insensitive to the underlying inter - particle interactions at short ranges . these low - energy properties can be investigated in the framework of effective field theory with two - body and three - body contact interactions . i review the effective - field - theory studies of universal physics in three - body systems , focusing on the application in cold atoms and halo nuclei . . And you have already written the first three sentences of the full article: although physics in cold atoms and halo nuclei are driven by interactions at very different physical scales , these systems share common features in their respective low energy regimes . universal behavior occurs when a system satisfies a separation of a large length scale and a small one . the large length scale is characterized by the scattering length @xmath0 , which determines the total cross section of the two - body s - wave scattering at zero energy by @xmath1 . for identical fermions . ]. Please generate the next two sentences of the article

the small length scale is represented by the range of two - body interactions @xmath2 . in the limit @xmath3 , physics at the scale of @xmath0 is disentangled from physics at the scale of @xmath2 , and is therefore insensitive to the details of the short - range interactions .

Suppose that you have an abstract for a scientific paper: i explore entanglement dynamics in a three qubit system comparing the ability of entanglement witnesses to detect tri - partite entanglement to the phenomenon of entanglement sudden death ( esd ) . using a system subject to dephasing i invoke entanglement witnesses to detect tri - partite ghz and w - type entanglement and compare the evolution of their detection capabilites with the evolution of the negativity , bi - partite concurrence , and tri - partite negativity . interestingly , i find a state in which there is no concurrence or tri - partite negativity but there is entanglement . finally , i utilize a three qubit quantum error correction ( qec ) code to address how esd affects the abilities of quantum error correction . . And you have already written the first three sentences of the full article: entanglement is a uniquely quantum mechanical phenomenon in which quantum systems exhibit correlations not possible for classical systems . as such , entanglement is a vital resource for many aspect of quantum information processing including quantum computation , quantum metrology , and quantum communication @xcite . but despite its fundamental and practical importance and much work in the subject , there are many aspects of entanglement , especially multi - partite entanglement , that are in need of further study @xcite . a major challenge facing experimental implementations of quantum computation , sensing , and communication is decoherence , unwanted interactions between the system and environment .. Please generate the next two sentences of the article

decoherence may be especially detrimental to highly non - classical , and hence most potentially useful , entangled states @xcite . a manifestation of this is entanglement suddent death ( esd ) in which entanglement is completely lost in a finite time @xcite despite the fact that the coherence loss of the system is asymptotic .

Suppose that you have an abstract for a scientific paper: we report detailed studies of the ac susceptibility butterfly hysteresis on the ru1222 ruthenocuprate compounds . two separate contributions to these hysteresis have been identified and studied . one contribution is ferromagnetic - like and is characterized by the coercive field maximum . another contribution , represented by the so called inverted maximum , is related to the unusual inverted loops , unique feature of ru1222 butterfly hysteresis . the different nature of the two identified magnetic contributions is proved by the different temperature dependences involved . by lowering the temperature the inverted peak gradually disappears while the coercive field slowly raises . if the maximum dc field for the hysteresis is increased , the size of the inverted part of the butterfly hysteresis monotonously grows while the position of the peak saturates . in reaching saturation exponential field dependence has been demonstrated to take place . at t = 78 k the saturation field is 42 oe . . And you have already written the first three sentences of the full article: the interplay between superconducting and magnetic order in ruthenocuprates raised considerable interest for these materials . they exist in three modifications , rusr@xmath0recu@xmath0o@xmath1 ( ru1212 ) , rusr@xmath0re@xmath2ce@xmath3cu@xmath0o@xmath4 ( ru1222 ) and , recently synthesized @xcite , rusr@xmath0rece@xmath0cu@xmath0o@xmath5 ( ru1232 ) ( re = gd , eu for ru1212 and ru1222 ; re = y , dy for ru1232 ) . neutron scattering measurements on ru1212 @xcite have revealed the existence of the antiferromagnetic order in ru - sublattice below 130 k , although ferromagnetic - like features have been observed in magnetization measurements @xcite .. Please generate the next two sentences of the article

measurements of microwave absorption @xcite , ac susceptibility @xcite , nmr @xcite have shown an evidence of the spontaneous vortex phase as an explanation for the coexistence of the superconductivity and magnetism below sc transition around 30 k. on the other hand , xue et al . @xcite have suggested the nanoscale separation between ferromagnetic and antiferromagnetic islands . as for the ru1222 composition , the magnetic structure is still unknown .

Suppose that you have an abstract for a scientific paper: we deal with the asymptotic behavior of the @xmath0-perimeter of a set @xmath1 inside a domain @xmath2 as @xmath3 . we prove necessary and sufficient conditions for the existence of such limit , by also providing an explicit formulation in terms of the lebesgue measure of @xmath1 and @xmath2 . moreover , we construct examples of sets for which the limit does not exist . serena dipierro alessio figalli giampiero palatucci enrico valdinoci ( communicated by the associate editor name ) . And you have already written the first three sentences of the full article: given @xmath4 and a bounded open set @xmath5 with @xmath6-boundary , the @xmath0-perimeter of a ( measurable ) set @xmath7 in @xmath2 is defined as @xmath8 where @xmath9 denotes the complement of @xmath1 , and @xmath10 denotes the following nonlocal interaction term @xmath11 here we are using the standard convention for which @xmath12 if either @xmath13 or @xmath14 . this notion of @xmath0-perimeter and the corresponding minimization problem were introduced in @xcite ( see also the pioneering work @xcite , where some functionals related to the one in have been analyzed in connection with fractal dimensions ) . recently , the @xmath0-perimeter has inspired a variety of literature in different directions , both in the pure mathematical settings ( for instance , as regards the regularity of surfaces with minimal @xmath0-perimeter , see @xcite ) and in view of concrete applications ( such as phase transition problems with long range interactions , see @xcite ) . in general , the nonlocal behavior of the functional is the source of major difficulties , conceptual differences , and challenging technical complications .. Please generate the next two sentences of the article

we refer to @xcite for an introductory review on this subject . the limits as @xmath3 and @xmath15 are somehow the critical cases for the @xmath0-perimeter , since the functional in diverges as it is . nevertheless , when appropriately rescaled , these limits seem to give meaningful information on the problem .

Suppose that you have an abstract for a scientific paper: we report and discuss case study simulations of the rayleigh - taylor instability in the boussinesq , incompressible regime developed to turbulence . our main focus is on a statistical analysis of density and velocity fluctuations inside of the already developed and growing in size mixing zone . novel observations reported in the article concern self - similarity of the velocity and density fluctuations spectra inside of the mixing zone snapshot , independence of the spectra of the horizontal slice level , and universality showing itself in a virtual independence of the internal structure of the mixing zone , measured in the re - scaled spatial units , of the initial interface perturbations . , . And you have already written the first three sentences of the full article: the rayleigh - taylor instability occurs when a heavy fluid is being pushed by a light fluid . two plane - parallel layers of fluid , colder on top , are in equilibrium while the slightest perturbation leads to the denser fluid moving down and the lighter material being displaced upwards . the early , linear stage of the instability was described by rayleigh @xcite and taylor @xcite , and summarized in @xcite .. Please generate the next two sentences of the article

further development of the instability leads to enhancement of the mixing and to a gradual increase of the mixing zone , which is the domain where proportions of heavy in light and light in heavy are comparable . dimensional arguments , supported by large - scale modeling @xcite , suggest that the half - width of the mixing zone , @xmath0 , grows quadratically at late time , @xmath1 , where @xmath2 is the atwood number characterizing the initial density contrast , @xmath3 is the gravitational acceleration , and @xmath4 is a dimensionless coefficient .

Suppose that you have an abstract for a scientific paper: diverse models of engines energised by quantum - coherent , hence non - thermal , baths allow the engine efficiency to transgress the standard thermodynamic carnot bound . these transgressions call for an elucidation of the underlying mechanisms . here we show that non - thermal baths may impart not only heat , but also mechanical work to a machine . the carnot bound is inapplicable to such a hybrid machine . intriguingly , it may exhibit dual action , concurrently as engine and refrigerator , with up to 100% efficiency . we conclude that even though a machine powered by a quantum bath may exhibit an unconventional performance , it still abides by the traditional principles of thermodynamics . . And you have already written the first three sentences of the full article: scully and co - workers @xcite have introduced a model of a carnot heat engine based on a bath comprised of partly - coherent three - level atoms ( nicknamed `` phaseonium '' ) that interact with a cavity - mode `` working fluid '' ( wf ) while they cross the cavity . their astounding conclusion was that the efficiency of such an engine may exceed the universal carnot bound @xcite because the phaseonium bath endows the cavity mode with a temperature @xmath0 that , depending on the phase @xmath1 of the atomic coherence , may surpass the corresponding temperature of thermal atoms without coherence . this research has initiated diverse suggestions of quantum resources for boosting heat - machine efficiency above the carnot bound , with a focus on non - thermal baths possessing quantum coherence @xcite . in traditional heat engines , energy exchange between the wf and the ( hot and cold ) thermal baths are entropy - changing heat transfers , whereas parametric changes of the wf hamiltonian are isentropic processes that produce or invest work @xcite .. Please generate the next two sentences of the article

the main questions we raise here are : does the same division between heat and work necessarily hold in engines fuelled by non - thermal ( quantum - coherent ) baths and how does this division affect the engine efficiency ? to what extent is the quantum character of non - thermal baths and ( or ) the wf relevant to the engine performance ? here we address the above questions by means of the fundamental notion of _ non - passivity _ @xcite that defines the ability of a quantum state to deliver work . the maximal work extractable from a non - passive state is known as ergotropy @xcite ( [ app_ergotropy ] ) .

Suppose that you have an abstract for a scientific paper: we perform an exact enumeration study of polymers formed from a ( quenched ) random sequence of charged monomers @xmath0 . such polymers , known as polyampholytes , are compact when completely neutral and expanded when highly charged . our exhaustive search included all spatial conformations and quenched sequences for up to 12step ( 13site ) walks . we investigate the behavior of the polymer as a function of its overall excess charge @xmath1 , and temperature @xmath2 . at low temperatures there is a phase transition from compact to extended configurations when the charge exceeds @xmath3 . there are also indications of a transition for small @xmath1 between two compact states on varying temperature . numerical estimates are provided for the condensation energy , surface tension , and the critical exponent @xmath4 . . And you have already written the first three sentences of the full article: given their ubiquity in nature , long chain macromolecules have been the subject of considerable study . whereas there is now a reasonably firm basis for understanding the physical properties of homopolymers@xcite , considerably less is known about the heteropolymers of biological significance . from a biologist s perspective , it is the specific properties of a particular molecule that are of interest . after all the genetic information is coded by very specific sequences of nucleic acids , which are in turn translated to the chain of amino acids forming a protein@xcite .. Please generate the next two sentences of the article

the energy of the polymer is determined by the van der waals , hydrogen bonding , hydrophobic / hydrophilic , and coulomb interactions between its constituent amino acids . in accord to these interactions , the protein folds into a specific shape that is responsible for its activity .

Suppose that you have an abstract for a scientific paper: the chaotic sea below the lowest energy spanning curve of the complete fermi - ulam model ( fum ) is numerically investigated when the amplitude of oscillation @xmath0 of the moving wall is small . we use scaling analysis near the integrable to non - integrable transition to describe the average energy as function of time @xmath1 and as function of iteration ( or collision ) number @xmath2 . if @xmath1 is employed as independent variable , the exponents related to the energy scaling properties of the fum are different from the ones of a well known simplification of this model ( sfum ) . however , if @xmath2 is employed as independent variable , the exponents are the same for both fum and sfum . in the collision number analysis , we present analytical arguments supporting that the exponents @xmath3 and @xmath4 related to the initial velocity and to @xmath0 are given by @xmath5 and @xmath6 . we derive also a relation connecting the scaling exponents related to the variables time and collision number . moreover , we show that , differently from the sfum , the average energy in the fum _ saturates _ for long times and we justify the physical origins for some differences and similarities observed between the fum and its simplification . . And you have already written the first three sentences of the full article: the fermi accelerator is a dynamical system , proposed by enrico fermi @xcite to describe cosmic ray acceleration , in which a charged particle collides with a time dependent magnetic field . with base in different applications , the original model was later modified and studied by other authors . one of them is the well known fermi - ulam model ( fum ) @xcite , in which a ball is confined between a rigid fixed wall and an oscillatory moving one . in this model. Please generate the next two sentences of the article

the ball collides elastically with the walls and the system is described by an area preserving map . in high energies regime the phase space presents kolmogorov - arnold - moser ( kam ) islands surrounded by locally chaotic regions , which are limited by spanning curves . below the invariant spanning curve of lower energy

Suppose that you have an abstract for a scientific paper: the dynamical instability of new - born neutron stars is studied by evolving the linearized hydrodynamical equations . the neutron stars considered in this paper are those produced by the accretion induced collapse of rigidly rotating white dwarfs . a dynamical bar - mode ( @xmath0 ) instability is observed when the ratio of rotational kinetic energy to gravitational potential energy @xmath1 of the neutron star is greater than the critical value @xmath2 . this bar - mode instability leads to the emission of gravitational radiation that could be detected by gravitational wave detectors . however , these sources are unlikely to be detected by ligo ii interferometers if the event rate is less than @xmath3 per year per galaxy . nevertheless , if a significant fraction of the pre - supernova cores are rapidly rotating , there would be a substantial number of neutron stars produced by the core collapse undergoing bar - mode instability . this would greatly increase the chance of detecting the gravitational radiation . 0.5 cm pacs : 04.30.db , 95.30.sf , 97.60.jd 2 . And you have already written the first three sentences of the full article: neutron stars are believed to form from the core collapse of massive stars and the accretion induced collapse of massive white dwarfs . if the stellar core or white dwarf is rotating , conservation of angular momentum implies that the resulting neutron star must rotate very rapidly . it has been suggested @xcite that such a rapidly rotating star may develop a non - axisymmetric dynamical instability , emitting a substantial amount of gravitational radiation which might be detectable by gravitational wave observatories such as ligo , virgo , geo and tama .. Please generate the next two sentences of the article

rotational instabilities arise from non - axisymmetric perturbations having angular dependence @xmath4 , where @xmath5 is the azimuthal angle . the @xmath0 mode is called the bar mode , which is usually the strongest mode for stars undergoing instabilities .

Suppose that you have an abstract for a scientific paper: an _ ab initio _ hartree - fock approach aimed at directly obtaining the localized orthogonal orbitals ( wannier functions ) of a crystalline insulator is described in detail . the method is used to perform all - electron calculations on the ground states of crystalline lithium fluoride and lithium chloride , without the use of any pseudo or model potentials . quantities such as total energy , x - ray structure factors and compton profiles obtained using the localized hartree - fock orbitals are shown to be in excellent agreement with the corresponding quantities calculated using the conventional bloch - orbital based hartree - fock approach . localization characteristics of these orbitals are also discussed in detail . . And you have already written the first three sentences of the full article: electronic - structure calculations on periodic systems are conventionally done using the so - called bloch orbital based approach which consists of assuming an itinerant form for the single - electron wave functions . this approach has the merit of incorporating the translational invariance of the system under consideration , as well as its infinite character , in an elegant and transparent manner . an alternative approach to electronic - structure calculations on periodic systems was proposed by wannier @xcite . in this approach , instead of describing the electrons in terms of itinerant bloch orbitals , one describes them in terms of mutually orthogonal orbitals localized on individual atoms or bonds constituting the infinite solid . since then such orbitals have come to be known as wannier functions .. Please generate the next two sentences of the article

it can be shown that the two approaches of description of an infinite solid are completely equivalent and that the two types of orbitals are related by a unitary transformation @xcite . therefore , the two approaches differ only in terms of their practical implementation

Suppose that you have an abstract for a scientific paper: consider the celebrated lyness recurrence @xmath0 with @xmath1 . first we prove that there exist initial conditions and values of @xmath2 for which it generates periodic sequences of rational numbers with prime periods @xmath3 or @xmath4 and that these are the only periods that rational sequences @xmath5 can have . it is known that if we restrict our attention to positive rational values of @xmath2 and positive rational initial conditions the only possible periods are @xmath6 and @xmath7 . moreover 1-periodic and 5-periodic sequences are easily obtained . we prove that for infinitely many positive values of @xmath8 positive 9-period rational sequences occur . this last result is our main contribution and answers an open question left in previous works of bastien & rogalski and zeeman . we also prove that the level sets of the invariant associated to the lyness map is a two - parameter family of elliptic curves that is a universal family of the elliptic curves with a point of order @xmath9 including @xmath10 infinity . this fact implies that the lyness map is a universal normal form for most birrational maps on elliptic curves . _ 2000 mathematics subject classification : _ ` 39a20 , 39a11,14h52 . ` _ keywords : _ lyness difference equations , rational points over elliptic curves , periodic points , universal family of elliptic curves . . And you have already written the first three sentences of the full article: the dynamics of the lyness recurrence @xmath11 specially when @xmath12 has focused the attention of many researchers in the last years and it is now completely understood in its main features after the independent research of bastien & rogalski @xcite and zeeman @xcite , and the later work of beukers & cushman @xcite . see also @xcite . in particular all possible periods of the recurrences generated by are known and for any @xmath13 infinitely many different prime periods appear .. Please generate the next two sentences of the article

however there are still some open problems concerning the dynamics of rational points . with the computer experiments in mind , and following @xcite , it is interesting to know the existence of rational periodic sequences . the lyness map @xmath14 associated to , leaves invariant the elliptic curves and @xmath2 the curve is not elliptic . we study these values separately . ] @xmath15 and the map action can be described in terms of the group law action of them . in consequence

Suppose that you have an abstract for a scientific paper: synchrotron radiation x - ray absorption and emission spectroscopy techniques , complemented by high - resolution transmission electron microscopy methods and density functional theory calculations are employed to investigate the effect of mn in al@xmath0ga@xmath1n : mn samples with an al content up to 100% . the atomic and electronic structure of mn is established together with its local environment and valence state . a dilute alloy without precipitation is obtained for al@xmath0ga@xmath1n : mn with al concentrations up to 82% , and the surfactant role of mn in the epitaxial process is confirmed . + = 0 = 0 . And you have already written the first three sentences of the full article: hetero - structures based on iii - nitrides @xcite and in particular on the combination al@xmath0ga@xmath1n / gan represent the basis of a variety of state - of - the - art ( opto)electronic devices like blue and white light - emitting diodes @xcite , laser diodes @xcite , blue lasers @xcite , high - power- @xcite , and high - electron - mobility - transistors @xcite . most of the above mentioned devices are commercially available and their performance continuously improved . furthermore , iii - nitrides doped with transition metals ( tm ) have also been the focus of considerable research efforts towards the demonstration of semiconductor spintronic functionalities @xcite . in this respect , while a remarkable number of reports on gan : mn provide an overview on the structural , optical , magnetic and electric properties of this material system @xcite , little is known about al@xmath0ga@xmath1n : mn @xcite and related nanostructures @xcite .. Please generate the next two sentences of the article

recent findings @xcite indicate this alloy as particularly interesting for _ e.g. _ the self - assembling of functional multilayers and for having revealed the decisive role of mn as surfactant during the epitaxial growth of al@xmath0ga@xmath1n : mn , considerably enhancing the critical thickness of al@xmath0ga@xmath1n : mn on gan , and opening new perspectives for the realization of _ e.g. _ improved reflectors in gan - based laser structures . we report here on al@xmath0ga@xmath1n : mn grown by means of metalorganic vapor phase epitaxy ( movpe ) in a broad range of al concentrations and extensively investigated @xmath2 x - ray absorption spectroscopy ( xas ) , x - ray emission spectroscopy ( xes ) , energy - dispersive spectrometry ( eds ) , x - ray diffraction ( xrd ) , and high - resolution ( hr ) transmission electron microscopy ( tem ) , supported by density functional theory ( dft ) calculations . the results

Suppose that you have an abstract for a scientific paper: these lecture notes provide an introduction to mm / submm extragalactic astronomy , focused on agn studies , with the final goal of preparing students to their future exploitation of the alma capabilities . i first provide an overview of the current results obtained through mm / submm observations of galaxies and agns , both local and at high redshift . then i summarize the main mm / submm facilities that are currently available . alma is then presented with a general description and by providing some details on its observing capabilities . finally , i discuss some of the scientific goals that will be achievable with alma in extragalactic astronomy , and for agn studies in particular . galaxies : active , evolution , formation , high - redshift , nuclei , quasars , seyfert , starburst , millimeter , submillimeter , instrumentation : high angular resolution , interferometers 95.85.fm , 95.85.bh , 98.54.-h , 98.54.cm , 98.54.ep , 98.54.kt . And you have already written the first three sentences of the full article: the atacama large millimeter array ( alma ) is one of the largest ground - based astronomy projects of the next decade , which will revolutionize several fields of astronomy . a large community of scientists is expected to use alma to tackle several outstanding questions in astrophysics . however , mm / submm astronomy is often considered a field restricted to experts . in the case of students and young scientists in particular ,. Please generate the next two sentences of the article

the limited familiarity with mm / submm facilities and observations may prevent them to fully exploit the alma capabilities in the future . these lecture notes are aimed at providing students and young researches some background on mm / submm extragalactic astronomy , with a focus on the investigation of agns .

Suppose that you have an abstract for a scientific paper: we present calculations of the exchange interactions and curie temperatures in cr - based pnictides and chalcogenides of the form crx with x = as , sb , s , se and te , and the mixed alloys cras@xmath0x@xmath0 with x = sb , s , se , and te . the calculations are performed for zinc blende ( zb ) structure for 12 values of the lattice parameter between 5.44 and 6.62 , appropriate for some typical ii - vi and iii - v semiconducting substrates . electronic structure is calculated via the linear muffin - tin - orbitals ( lmto ) method in the atomic sphere approximation ( asa ) , using empty spheres to optimize asa - related errors . whenever necessary , the results have been verified using the full - potential version of the method , fp - lmto . the disorder effect in the as - sublattice for cras@xmath0x@xmath0 ( x = sb , s , se , te ) alloys is taken into account via the coherent potential approximation ( cpa ) . exchange interactions are calculated using the linear response method for the ferromagnetic ( fm ) reference states of the alloys , as well as the disordered local moments ( dlm ) states . these results are then used to estimate the curie temperature from the low and high temperature side of the ferromagnetic / paramagnetic transition . estimates of the curie temperature are provided , based on the mean field and the more accurate random phase approximations . dominant antiferromagnetic exchange interactions for some low values of the lattice parameter for the fm reference states in crs , crse and crte prompted us to look for antiferromagnetic ( afm ) configurations for these systems with energies lower than the corresponding fm and dlm values . results for a limited number of such afm calculations are discussed , identifying the afm[111 ] state as a likely candidate for the ground state for these cases . . And you have already written the first three sentences of the full article: half - metallic ferromagnets with high ( room temperature and above ) curie temperatures @xmath1 are ideal for spintronics applications , and as such , much experimental and theoretical@xcite effort has been devoted in recent years to the designing of and search for such materials . among these , cr - doped dilute magnetic semiconductors ( dms ) @xcite or cr - based alloys and in particular cras and crsb @xcite in zinc blende(zb ) structure have attracted particular attention , not only because of the possibility of complete spin polarization of the carriers at the fermi level , but also for their possible high @xmath1 . akinaga @xcite were able to grow zb thin films of cras on gaas ( 001 ) substrates by molecular beam epitaxy , which showed ferromagnetic behavior at temperatures in excess of 400 k and magnetic moments of 3@xmath2 per cras unit .. Please generate the next two sentences of the article

theoretical calculations by akinaga @xcite and several other theoretical calculations since then @xcite have verified the half - metallic character of cras . the high value of @xmath1 has also been supported by some of these studies@xcite .

Suppose that you have an abstract for a scientific paper: selected topics on precision tests of the standard model of the electroweak and the strong interaction at the lep @xmath0 collider are presented , including an update of the world summary of measurements of @xmath1 , representing the state of knowledge of summer 1999 . this write - up of lecture notes consists of a reproduction of slides , pictures and tables , supplemented by a short descriptive text and a list of relevant references . 0z^0 2d_2 2 ^ 2 l 2q^2 mpi - phe/2000 - 02 + january 2000 . And you have already written the first three sentences of the full article: the physics of elementary particles and forces determined the development of the early universe and thus , of the structure of our world today ( * fig . 1 * ) . according to our present knowledge , three families of quarks and leptons , four fundamental interactions , their respective exchange bosons and a yet - to - discover mechanism to generate particle masses are the ingredients ( * fig . 2 * ) which are necessary to describe our universe , both at cosmic as well as at microscopic scales . three of the four forces are relevant for particle physics at small distances : the strong , the electromagnetic and the weak force .. Please generate the next two sentences of the article

they are described by quantum field theories , quantum chromodynamics ( qcd ) for the strong , quantum - electrodynamics ( qed ) for the electromagnetic and the so - called standard model of the unified electro - weak interactions @xcite . the weakest force of the four , gravitation , is the major player only at large distances where the other three are , in general , not relevant any more : the strong and the weak force are short - ranged and thus limited to sub - nuclear distances , the electromagnetic force only acts between objects whose net electric charge is different from zero . of the objects listed in * fig .

Suppose that you have an abstract for a scientific paper: a microscopic calculation of the perpendicular current in doped multiple quantum wells is presented . interface roughness is shown to affect the resonant transitions as well as to cause a nonresonant background current . the theoretical characteristics exhibit several branches due to the formation of electric field domains in quantitative agreement with experimental data . . And you have already written the first three sentences of the full article: the electric transport in semiconductor superlattices is usually dominated by resonances between the localized energy levels inside the wells resulting in peaks in the current - field relation . this may yield complicated current - voltage characteristics exhibiting may branches due to the formation of domains of different electric field inside the sample ( see , e.g. , @xcite and references therein ) . these experimental features could be qualitatively reproduced by theoretical models combining rate equations for the transport between the wells and poisson s equation @xcite .. Please generate the next two sentences of the article

while these approaches assume interwell transition rates which are either fitted or obtained from phenomenological models , we have recently proposed a way to calculate the transport microscopically @xcite . we obtained good quantitative agreement with the experimental data of ref .

Suppose that you have an abstract for a scientific paper: high - accuracy astrometry permits the determination of not only stellar tangential motion , but also the component along the line - of - sight . such non - spectroscopic ( i.e. astrometric ) radial velocities are independent of stellar atmospheric dynamics , spectral complexity and variability , as well as of gravitational redshift . three methods are analysed : ( 1 ) changing annual parallax , ( 2 ) changing proper motion and ( 3 ) changing angular extent of a moving group of stars . all three have significant potential in planned astrometric projects . current accuracies are still inadequate for the first method , while the second is marginally feasible and is here applied to 16 stars . the third method reaches high accuracy ( @xmath0 km s@xmath1 ) already with present data , although for some clusters an accuracy limit is set by uncertainties in the cluster expansion rate . . And you have already written the first three sentences of the full article: for well over a century , radial velocities for objects outside the solar system have been determined through spectroscopy , using the ( doppler ) shifts of stellar spectral lines . the advent of high - accuracy ( sub - milliarcsec ) astrometric measurements , both on ground and in space , now permits radial velocities to be obtained by alternative methods , based on geometric principles and therefore independent of spectroscopy . the importance of such _ astrometric radial velocities _ stems from the fact that they are independent of phenomena which affect the spectroscopic method , such as line asymmetries and shifts caused by atmospheric pulsation , surface convection , stellar rotation , stellar winds , isotopic composition , pressure , and gravitational potential .. Please generate the next two sentences of the article

conversely , the differences between spectroscopic and astrometric radial velocities may provide information on these phenomena that can not be obtained by other methods . although the theoretical possibility of deducing astrometric radial velocities from geometric projection effects was noted already at the beginning of the 20th century ( if not earlier ) , it is only recently that such methods have reached an accuracy level permitting non - trivial comparison with spectroscopic measurements .

Suppose that you have an abstract for a scientific paper: dust ion acoustic solitary structures have been investigated in an unmagnetized nonthermal plasma consisting of negatively charged dust grains , adiabatic positive ions and nonthermal electrons . for isothermal electrons , the present plasma system does not support any double layer solution , whereas for nonthermal electrons , negative potential double layer starts to occur whenever the nonthermal parameter exceeds a critical value . however this double layer solution is unable to restrict the occurrence of all negative potential solitary waves of the present system . as a result , two different types of negative potential solitary waves have been observed , in which occurrence of first type of solitary wave is restricted by @xmath0 whereas the second type solitary wave exists for all @xmath1 , where @xmath2 is the lower bound of mach number @xmath3 , i.e. , solitary structures start to exist for @xmath4 and @xmath5 is the mach number corresponding to a negative potential double layer . a finite jump between the amplitudes of negative potential of solitary waves at @xmath6 and at @xmath7 has been observed , where @xmath8 and @xmath9 . as double layer solution plays an important role for the present system , an analytical theory for the existence of double layer has been presented . a numerical scheme has also been provided to find the value of mach number at which double layer solution exists and also the amplitude of that double layer . the solitary structures of both polarities can coexist whenever @xmath10 exceeds a critical value , where @xmath10 is the ratio of the unperturbed number density of electrons to that of ions . although the occurrence of coexistence of solitary structures of both polarities is restricted by @xmath11 , only negative potential solitary wave still exists for all @xmath12 , where @xmath13 is the upper bound of @xmath3 for the existence of positive potential solitary waves only . qualitatively different solution spaces , i.e. , the compositional parameter spaces.... And you have already written the first three sentences of the full article: acoustic wave modes in dusty plasma have received a great deal of attention since the last decade @xcite . depending on different time scales , there can exists two or more acoustic waves in a typical dusty plasma . dust acoustic ( da ) and dust ion - acoustic ( dia ) waves are two such acoustic waves in a plasma containing electrons , ions , and charged dust grains .. Please generate the next two sentences of the article

shukla and silin @xcite were the first to show that due to the quasi neutrality condition @xmath15 and the strong inequality @xmath16 ( @xmath17 , @xmath18 , and @xmath19 are , respectively , the number density of electrons , ions , and dust particles , where @xmath20 is the number of electrons residing on the dust grain surface ) , a dusty plasma ( with negatively charged static dust grains ) supports low - frequency dia waves with phase velocity much smaller ( larger ) than electron ( ion ) thermal velocity . in case of long wavelength limit the dispersion relation of dia wave is similar to that of ion - acoustic ( ia ) wave for a plasma with @xmath21 and @xmath22 , where @xmath23 is the average ion ( electron ) temperature . due to the usual dusty plasma approximations ( @xmath16 and @xmath24 ) , a dusty plasma can not support the usual ia waves , but the dia waves of shukla and silin @xcite can .

Suppose that you have an abstract for a scientific paper: a proximity focusing ring imaging cherenkov detector using aerogel as the radiator has been studied for an upgrade of the belle detector at the kek - b - factory . we constructed a prototype cherenkov counter using a @xmath0 array of 64-channel flat - panel multi - anode pmts ( hamamatsu h8500 ) with a large effective area . the aerogel samples were made with a new technique to obtain a higher transmission length at a high refractive index ( @xmath1 ) . multi - channel pmts are read - out with analog memory chips . the detector was tested at the kek - ps @xmath2 beam line in november , 2002 . to evaluate systematically the performance of the detector , tests were carried out with various aerogel samples using pion beams with momenta between 0.5 gev/@xmath3 and 4 gev/@xmath3 . the typical angular resolution was around 14 mrad , and the average number of detected photoelectrons was around 6 . we expect that pions and kaons can be separated at a 4@xmath4 level at @xmath5 . aerogel , flat - panel pmt , ring imaging cherenkov counter , proximity focusing , particle identification , belle 29.40.ka . And you have already written the first three sentences of the full article: silica aerogel is a unique material with a refractive index ( @xmath6 ) in the range between gases and liquids or solids . its refractive index can be easily controlled from @xmath7 to @xmath8 . as a result , the refractive index of the aerogel can be chosen such that for a given momentum interval in the few gev/@xmath3 region charged pions radiate cherenkov photons , while kaons stay below the cherenkov radiation threshold @xcite . in the belle experiment at kek @xcite , a threshold type cherenkov detector ( belle - acc ) @xcite which uses aerogel as a radiator ,. Please generate the next two sentences of the article

is operated , providing at @xmath9 a kaon identification efficiency of @xmath10% with a pion missidentification probability of @xmath11% @xcite . a new production method of hydrophobic aerogel with a high transmission length and @xmath6 in the interval between @xmath12 and @xmath13 was developed during the construction period of belle - acc @xcite .

Suppose that you have an abstract for a scientific paper: the problem of the nonequivalence of the sets of equilibrium points and energy - casimir extremal points , which occurs in the noncanonical hamiltonian formulation of equations describing ideal fluid and plasma dynamics , is addressed in the context of the euler equation for an incompressible inviscid fluid . the problem is traced to a casimir deficit , where casimir elements constitute the center of the poisson algebra underlying the hamiltonian formulation , and this leads to a study of singularities of the poisson operator defining the poisson bracket . the kernel of the poisson operator , for this typical example of an infinite - dimensional hamiltonian system for media in terms of eulerian variables , is analyzed . for two - dimensional flows , a rigorously solvable system is formulated . the nonlinearity of the euler equation makes the poisson operator inhomogeneous on phase space ( the function space of the state variable ) , and it is seen that this creates a singularity where the nullity of the poisson operator ( the `` dimension '' of the center ) changes . the problem is an infinite - dimension generalization of the theory of singular differential equations . singular casimir elements stemming from this singularity are unearthed using a generalization of the functional derivative that occurs in the poisson bracket . . And you have already written the first three sentences of the full article: equations that describe ideal fluid and plasma dynamics in terms of eulerian variables are hamiltonian in terms of noncanonical poisson brackets , degenerate brackets in noncanonical coordinates . because of degeneracy , such poisson brackets possess casimir elements , invariants that have been used to construct variational principles for equilibria and stability . however , early on it was recognized that typically there are not enough casimir elements to obtain all equilibria as extremal points of these variational principles . in @xcite. Please generate the next two sentences of the article

it was noted that this casimir deficit is attributable to rank changing of the operator that defines the noncanonical poisson bracket . thus , a mathematical study of the kernel of this operator is indicated , and this is the main purpose of the present article . recognizing a hamiltonian flow as a differential operator , the point where the rank of the poisson bracket changes is a singularity , from which singular ( or intrinsic ) solutions stem .

Suppose that you have an abstract for a scientific paper: we describe a method for calculating the probability with which the wall of a plasma absorbs an electron at low energy . the method , based on an invariant embedding principle , expresses the electron absorption probability as the probability for transmission through the wall s long - range surface potential times the probability to stay inside the wall despite of internal backscattering . to illustrate the approach we apply it to a sio@xmath0 surface . besides emission of optical phonons inside the wall we take elastic scattering at imperfections of the plasma - wall interface into account and obtain absorption probabilities significantly less than unity in accordance with available electron - beam scattering data but in disagreement with the widely used perfect absorber model . . And you have already written the first three sentences of the full article: a surface facing a plasma collects electrons from the plasma more efficiently than it looses electrons due to neutralization of ions and/or de - excitation of radicals . it acquires thus a negative charge triggering in turn an electron - depletion layer in front of it the plasma sheath shielding the plasma from the surface . although known since the beginning of modern plasma physics @xcite a quantitative understanding of electron accumulation by plasma walls is still lacking @xcite .. Please generate the next two sentences of the article

this is only due partly to unresolved materials science aspects , such as , chemical contamination and/or mechanical destruction of the surface by the plasma . it is also because little is known fundamentally about the interaction of electrons with surfaces at the energies relevant for plasma applications .

Suppose that you have an abstract for a scientific paper: intermediate mass stars occupy the mass range between 0.8 - 8 . in this contribution , evolutionary models of these stars from numerous sources are compared in terms of their input physics and predicted yields . in particular , the results of renzini & voli , van den hoek & groenewegen , and marigo are discussed . generally speaking , it is shown that yields of 4 , , and 14 decrease with increasing metallicity , reduced mass loss rate , and increased rotation rate . integrated yields and recently published chemical evolution model studies are used to assess the relative importance of intermediate mass and massive stars in terms of their contributions to universal element buildup . intermediate mass stars appear to play a major role in the chemical evolution of 14 , a modest role in the case of , and a small role for 4 . furthermore , the time delay in their release of nuclear products appears to play an important part in explaining the apparent bimodality in the distribution of damped lyman-@xmath0 systems in the n/@xmath0@xmath0/h plane . [ 1996/06/01 ] a&a 4@xmath1he 14@xmath2n . And you have already written the first three sentences of the full article: intermediate - mass stars ( ims ) comprise objects with zams masses between 0.8 and 8 , corresponding to spectral types between g2 and b2 . the lower mass limit is the minimum value required for double shell ( h and he ) fusion to occur , resulting in thermal pulsations during the asymptotic giant branch ( agb ) phase and eventually planetary nebula formation . above the upper mass limit stars are capable of additional core - burning stages , and it is generally assumed that these stars become supernovae . a salpeter ( 1955 ) imf can be used to show that ims represent about 4% of all stars above 0.08 , but this may be a lower limit if the imf is flat at low stellar masses ( scalo 1998 ) .. Please generate the next two sentences of the article

ims evolution is an interesting and complex subject and the literature is extensive . a good , complete , generally accessible review of the subject is given by iben ( 1995 ) .

Suppose that you have an abstract for a scientific paper: we calculate the nucleon parameters in isospin symmetric and asymmetric nuclear matter using the qcd sum rules . the higher moments of the nucleon structure functions are included . the complete set of the nucleon expectation values of the four - quark operators is employed . we analyze the role of the lowest order radiative corrections beyond the logarithmic approximation . . And you have already written the first three sentences of the full article: we investigate the vector and scalar self - energies of nucleons in nuclear matter composed by the neutrons and protons , distributed with densities @xmath0 and @xmath1 . we calculate the dependence on the total density @xmath2 and on the asymmetry parameter @xmath3 . the qcd sum rules were invented in paper @xcite to express the hadron parameters through the vacuum expectation values of qcd operators .. Please generate the next two sentences of the article

being initially used for the mesons , the method was expanded in @xcite to the description of the baryons . the approach succeeded in describing the static characteristics as well as some of the dynamical characteristics of the hadrons in vacuum see , the reviews @xcite .

Suppose that you have an abstract for a scientific paper: many natural language processing ( nlp ) tasks can be generalized into segmentation problem . in this paper , we combine semi - crf with neural network to solve nlp segmentation tasks . our model represents a segment both by composing the input units and embedding the entire segment . we thoroughly study different composition functions and different segment embeddings . we conduct extensive experiments on two typical segmentation tasks : named entity recognition ( ner ) and chinese word segmentation ( cws ) . experimental results show that our neural semi - crf model benefits from representing the entire segment and achieves the state - of - the - art performance on cws benchmark dataset and competitive results on the conll03 dataset . . And you have already written the first three sentences of the full article: given an input sequence , _ segmentation _ is the problem of identifying and assigning tags to its subsequences . many natural language processing ( nlp ) tasks can be cast into the segmentation problem , like named entity recognition @xcite , opinion extraction @xcite , and chinese word segmentation @xcite . properly representing _ segment _ is critical for good segmentation performance . widely used sequence labeling models like conditional random fields @xcite represent the contextual information of the segment boundary as a proxy to entire segment and achieve segmentation by labeling input units ( e.g. words or characters ) with boundary tags .. Please generate the next two sentences of the article

compared with sequence labeling model , models that directly represent segment are attractive because they are not bounded by local tag dependencies and can effectively adopt segment - level information . semi - markov crf ( or semi - crf ) @xcite is one of the models that directly represent the entire segment . in semi - crf ,

Suppose that you have an abstract for a scientific paper: two - photon photoassociation of hot magnesium atoms by femtosecond laser pulses , creating electronically excited magnesium dimer molecules , is studied from first principles , combining _ ab initio _ quantum chemistry and molecular quantum dynamics . this theoretical framework allows for rationalizing the generation of molecular rovibrational coherence from thermally hot atoms [ l. rybak _ et al . _ , phys . rev . lett . * 107 * , 273001 ( 2011 ) ] . random phase thermal wave functions are employed to model the thermal ensemble of hot colliding atoms . comparing two different choices of basis functions , random phase wavefunctions built from eigenstates are found to have the fastest convergence for the photoassociation yield . the interaction of the colliding atoms with a femtosecond laser pulse is modeled non - perturbatively to account for strong - field effects . . And you have already written the first three sentences of the full article: molecules can be assembled from atoms using laser light . this process is termed photoassociation . with the advent of femtosecond lasers and pulse shaping techniques , photoassociation became a natural candidate for coherent control of a binary reaction . coherent control had been conceived as a method to determine the fate of chemical reactions using laser fields.@xcite the basic idea is to employ interference of matter waves to constructively enhance a desired outcome while destructively suppressing all undesired alternatives.@xcite control is exerted by shaping the laser pulses , the simplest control knobs being time delays and phase differences.@xcite over the last two decades , the field of coherent control has developed significantly both theoretically and experimentally.@xcite however , a critical examination of the achievements reveals that successful control has been demonstrated almost exclusively for unimolecular processes such as ionization , dissociation and fragmentation .. Please generate the next two sentences of the article

it is natural to ask why the reverse process of controlling binary reactions@xcite is so much more difficult . the main difference between unimolecular processes and a binary reaction lies in the initial state a single or few well - defined bound quantum states vs an incoherent continuum of scattering states.@xcite for a binary reaction , the nature of the scattering continuum is mainly determined by the temperature of the reactants . as temperature decreases ,

Suppose that you have an abstract for a scientific paper: we study an appell hypergeometric system @xmath0 of rank four which is reducible and show that its schwarz map admits geometric interpretations : the map can be considered as the universal abel - jacobi map of a @xmath1-dimensional family of curves of genus 2 . . And you have already written the first three sentences of the full article: schwarz maps for hypergeometric systems in single and several variables are studied by several authors ( cf . @xcite ) for more than hundred years . these systems treated were irreducible , maybe because specialists believed that reducible systems would not give interesting schwarz maps .. Please generate the next two sentences of the article

we study in this paper appell s hypergeometric system @xmath0 of rank four when its parameters satisfy @xmath2 or @xmath3 . in this case , the system @xmath0 is reducible , and has a @xmath4-dimensional subsystem isomorphic to appell s @xmath5 ( proposition [ prop : s2 ] ) . if @xmath6 then @xmath0 has two such subsystems . by proposition [ prop : s2 g ] , the intersection of these subsystems is equal to the gauss hypergeometric equation . as a consequence

Suppose that you have an abstract for a scientific paper: we derive a semi - analytic solution for the structure of conduction - mediated transition layers above an x - ray illuminated accretion disk , and calculate explicitly the x - ray line radiation resulting from both resonance line scattering and radiative recombination in these layers . the vertical thermal structure of the illuminated disk is found to depend on the illuminating continuum : for a hard power law continuum , there are two stable phases connected by a single transition layer ; while for a softer continuum , there may exist three stable phases connected by two separate transition layers , with an intermediate stable layer in between . we show that the structure can be written as a function of the electron scattering optical depth through these layers , which leads to unique predictions of the equivalent width of the resulting line radiation from both recombination cascades and resonance line scattering . we find that resonance line scattering plays an important role , especially for the case where there is no intermediate stable layer . . And you have already written the first three sentences of the full article: x - ray reflection off the surface of cold disks in active galactic nuclei ( agn ) and galactic black holes ( gbhs ) has been an active field of research since the work of @xcite . in early studies , the illuminated material was assumed to be cold and non - ionized @xcite . it was soon realized , however , that photoionization of the disk can have a great impact on both the reflected continuum and the iron fluorescence lines .. Please generate the next two sentences of the article

detailed calculations were then carried out by @xcite and @xcite . however , in all of these papers , the density of the illuminated material was assumed to be constant along the vertical direction . this assumption applies only to the simplest version of radiation - dominated shakura - sunyaev disks @xcite , and only for the portion where viscous dissipation is the dominating heating process . for the surface layers ,

Suppose that you have an abstract for a scientific paper: we present the first results of a survey of the emission line in 241 luminous infrared galaxies ( lirgs ) comprising the great observatories all - sky survey ( goals ) sample , obtained with the pacs instrument on board the _ herschel space observatory_. the luminosities , , of the lirgs in goals range from @xmath0 to 2@xmath1 . we find that lirgs show a tight correlation of /fir with far - ir flux density ratios , with a strong negative trend spanning from @xmath2 to @xmath3 , as the average temperature of dust increases . we find correlations between the /fir ratio and the strength of the 9.7@xmath4 m silicate absorption feature as well as with the luminosity surface density of the mid - ir emitting region ( @xmath5 ) , suggesting that warmer , more compact starbursts have substantially smaller /fir ratios . pure star - forming lirgs have a mean /fir@xmath6 , while galaxies with low equivalent widths ( ews ) , indicative of the presence of active galactic nuclei ( agn ) , span the full range in /fir . however , we show that even when only pure star - forming galaxies are considered , the /fir ratio still drops by an order of magnitude , from @xmath7 to @xmath8 , with @xmath5 and @xmath9 , implying that the luminosity is not a good indicator of the star formation rate ( sfr ) for most lirgs , for it does not scale linearly with the warm dust emission most likely associated to the youngest stars . moreover , even in lirgs in which we detect an agn in the mid - ir , the majority ( 2/3 ) of galaxies show /fir@xmath10 typical of high ew sources , suggesting that most agns do not contribute significantly to the far - ir emission . we provide an empirical relation between the /fir and the specific sfr ( ssfr ) for star - forming lirgs . finally , we present predictions for the starburst size based on the observed and far - ir luminosities which should be useful for comparing with results from future surveys of high - redshift galaxies with alma and ccat . . And you have already written the first three sentences of the full article: systematic spectroscopic observations of far - infrared ( ir ) cooling lines in large samples of local star - forming galaxies and active galactic nuclei ( agn ) were first carried out with _ iso _ ( e.g. , @xcite , 2001 ; @xcite ; @xcite ) . these studies showed that is the most intense far - ir emission line observed in normal , star - forming galaxies ( @xcite ) and starbursts ( e.g. , @xcite ; @xcite ) , dominating the gas cooling of their neutral inter stellar medium ( ism ) .. Please generate the next two sentences of the article

this fine - structure line arises from the @xmath11 transition ( @xmath12k ) of singley ionized carbon atoms ( ionization potential=11.26ev and critical density , @xmath13 ; @xmath14 ) which are predominantly excited by collisions with neutral hydrogen atoms ; or with free electrons and protons in regions where @xmath15 ( @xcite ) . ultraviolet ( uv ) photons with energies @xmath166ev emitted by newly formed stars are able to release the most weakly bound electrons from small dust grains via photo - electric heating ( @xcite ; @xcite ) . in particular , polycyclic aromatic hydrocarbons ( pahs )

Suppose that you have an abstract for a scientific paper: we study the distribution function of the three dimensional wormlike chain with a fixed orientation of one chain end using the exact representation of the distribution function in terms of the green s function of the quantum rigid rotator in a homogeneous external field . the transverse 1d distribution function of the free chain end displays a bimodal shape in the intermediate range of the chain lengths ( @xmath0 ) . we present also analytical results for short and long chains , which are in complete agreement with the results of previous studies obtained using different methods . . And you have already written the first three sentences of the full article: polymers with contour length @xmath1 much larger than the persistence length @xmath2 , which is the correlation length for the tangent - tangent correlation function along the polymer and is a quantitative measure of the polymer stiffness , are flexible and are described by using the tools of quantum mechanics and quantum field theory @xcite-@xcite . if the chain length decreases , the chain stiffness becomes an important factor . many polymer molecules have internal stiffness and can not be modeled by the model of flexible polymers developed by edwards @xcite .. Please generate the next two sentences of the article

the standard coarse - graining model of a wormlike polymer was proposed by kratky and porod @xcite . the essential ingredients of this model are the penalty for the bending energy and the local inextensibility .

Suppose that you have an abstract for a scientific paper: a graph is closed when its vertices have a labeling by @xmath0 $ ] with a certain property first discovered in the study of binomial edge ideals . in this article , we prove that a connected graph has a closed labeling if and only if it is chordal , claw - free , and has a property we call _ narrow _ , which holds when every vertex is distance at most one from all longest shortest paths of the graph . . And you have already written the first three sentences of the full article: in this paper , @xmath1 will be a simple graph with vertex set @xmath2 and edge set @xmath3 . [ closeddef ] a _ labeling _ of @xmath1 is a bijection @xmath4 = \{1,\dots , n\}$ ] , and given a labeling , we typically assume @xmath5 $ ] . a labeling is _ closed _ if whenever we have distinct edges @xmath6 with either @xmath7 or @xmath8 , then @xmath9 .. Please generate the next two sentences of the article

finally , a graph is _ closed _ if it has a closed labeling . a labeling of @xmath1 gives a direction to each edge @xmath10 where the arrow points from @xmath11 to @xmath12 when @xmath13 , i.e. , the arrow points to the bigger label .

Suppose that you have an abstract for a scientific paper: the advent of ultrahigh - power femtosecond lasers creates a need for optical components suitable to handle ultrahigh light intensities . due to the unavoidable laser - induced ionization of matter , these components will have to be based on a plasma medium . an archetype of such optical elements is a plasma mirror , created when an intense femtosecond laser pulse impinges on a solid target . it consists of a dense plasma , formed by the laser field itself , which specularly reflects the main part of the pulse . plasma mirrors have major potential applications as active optical elements to manipulate the temporal and spatial properties of intense laser beams , in particular for the generation of intense attosecond pulses of light . we investigate the basic physics involved in the deformation of a plasma mirror resulting from the light pressure exerted by the ultraintense laser during reflection , by deriving a simple model of this fundamental process , which we validate both numerically and experimentally . the understanding of this deformation is essential for all future applications of plasma mirrors , especially for the generation of collimated attosecond beams . we show how its effect on the attosecond beam divergence can be mitigated by using the laser phase , thus providing crucial control for future applications in attosecond science . + ultrafast laser technology now makes it possible to study the interaction of femtosecond ( fs ) laser pulses with plasmas in an extreme regime , where the motion of electrons in the laser field is relativistic @xcite . with several facilities aiming at peak powers beyond a petawatt , the study of new regimes of quantum electrodynamics should thus become feasible in the near future @xcite . the rapid growth in the number of high - power ultrashort lasers is also driven by the perspective of societal and scientific applications , such as compact laser - driven particle accelerators @xcite . these laser developments and their prospects.... And you have already written the first three sentences of the full article: properly describing the pm surface motion requires taking into account both the plasma electron and ion dynamics . the response time of electrons to the laser field is much smaller than the optical period , while ions react on a longer time scale due to their larger mass . akin to the born - oppenheimer approximation in molecular physics , this makes it possible to model the system in three steps : ( i ) we first describe the quasi - instantaneous response of electrons to the laser field , considering a given ion background ( fig.[sim1](a ) ) ; ( ii ) we then calculate the slow ion motion , resulting from the combined actions of the laser - field and of the charge separation fields it induces ( fig.[sim1](b ) ) and ( iii ) finally the influence of the slow dynamics on the fast one is included , to determine the surface motion over the entire laser pulse ( fig.[sim1](c ) ) .. Please generate the next two sentences of the article

the derivations of all formulas and their validation by particle - in - cell ( pic ) simulations are provided in the online supplementary information . qualitatively , the plasma electrons respond to the laser field as a spring , being alternatively pushed inside , and pulled outside of the ion background in each optical period @xcite .

Suppose that you have an abstract for a scientific paper: we present the results of a machine - learning ( ml ) based search for new r coronae borealis ( rcb ) stars and dy persei - like stars ( dypers ) in the galaxy using cataloged light curves from the all - sky automated survey ( asas ) catalog of variable stars ( acvs ) . rcb stars a rare class of hydrogen - deficient carbon - rich supergiants are of great interest owing to the insights they can provide on the late stages of stellar evolution . dypers are possibly the low - temperature , low - luminosity analogs to the rcb phenomenon , though additional examples are needed to fully establish this connection . while rcb stars and dypers are traditionally identified by epochs of extreme dimming that occur without regularity , the ml search framework more fully captures the richness and diversity of their photometric behavior . we demonstrate that our ml method can use newly discovered rcb stars to identify additional candidates within the same data set . our search yields 15 candidates that we consider likely rcb stars / dypers : new spectroscopic observations confirm that four of these candidates are rcb stars and four are dypers . our discovery of four new dypers increases the number of known galactic dypers from two to six ; noteworthy is that one of the new dypers has a measured parallax and is @xmath0 mag , making it the brightest known dyper to date . future observations of these new dypers should prove instrumental in establishing the rcb connection . we consider these results , derived from a machine - learned probabilistic classification catalog , as an important proof - of - concept for the efficient discovery of rare sources with time - domain surveys . . And you have already written the first three sentences of the full article: r coronae borealis ( rcb ) stars are hydrogen - deficient carbon ( hdc ) stars that exhibit spectacular ( @xmath1 up to @xmath28 mag ) , aperiodic declines in brightness ( for a review on rcb stars see @xcite ) . the fading occurs rapidly ( @xmath21 to few weeks ) as new dust is formed in the circumstellar environment , and the recovery is slow , sometimes taking several years , as the new dust is dispersed and removed from the line of sight . at maximum light rcb stars are bright supergiants , which in combination with the large - amplitude photometric variability should make them easy to discover . yet , to date there are only @xmath256 known rcb stars in the galaxy @xcite . the rarity of these stars suggests that they reflect a very brief phase of stellar evolution , or a bias in rcb star search methods , or both .. Please generate the next two sentences of the article

the lack of hydrogen and overabundance of carbon in rcb atmospheres implies that rcb stars are in a late stage of stellar evolution , but no consensus has yet emerged regarding their true physical nature . there are two leading theories for explaining the observed properties of rcb stars : the double degenerate ( dd ) scenario and the final helium shell flash ( ff ) scenario ( see e.g. , @xcite ) .

Suppose that you have an abstract for a scientific paper: we present accurate @xmath0-band photometry for a planetary transit of ogle - tr-111 acquired with vimos at the eso very large telescope . the measurement of this transit allows to refine the planetary radius , obtaining @xmath1 . given the mass of @xmath2 previously measured from radial velocities , we confirm that the density is @xmath3 . we also revise the ephemeris for ogle - tr-111-b , obtaining an accurate orbital period @xmath4 days , and predicting that the next observable transits would occur around december 2006 , and after that only in mid-2008 . even though this period is different from previously published values , we can not yet rule out a constant period . . And you have already written the first three sentences of the full article: the discovery of hot jupiters that transit in front of their parent stars has advanced our knowledge of extrasolar planets adding a fundamental datum : the planetary radius . there has been considerable activity revising the measured radii , owing to uncertainties in the differential image analysis ( see pont et al . 2006 ) . it is important to obtain accurate radii from photometry , in order to compare these exoplanets with the giant planets of the solar system , and with the models .. Please generate the next two sentences of the article

in addition , if accurate photometry of transits is available , one can use timing for future studies of multiplicity in these systems ( e.g. sartoretti & schneider 1999 , miralda - escude 2002 , holman & murray 2005 , agol et al . 2005 ) .

Suppose that you have an abstract for a scientific paper: in this article i review the main theoretical problems that are posed by the highest energy end of the observed cosmic ray spectrum , stressing the importance of establishing their composition in order to decide between proposed scenarios . i then discuss the possibilities that are opened by the detection of inclined showers with extensive air shower arrays . recent progress in modelling magnetic deviations for these showers has allowed the analysis of inclined showers that were detected by the haverah park experiment . this analysis disfavours models that predict a large proportion of photons in the highest energy cosmic rays and open up new possibilities for future shower array detectors particularly those , like the pierre auger observatory , using water erenkov detectors . . And you have already written the first three sentences of the full article: cosmic rays are elementary particles arriving at the earth from outside that were discovered in the beginning of the 20th century as one of the main sources of natural radiation . the cosmic ray spectrum has been observed as a continuum at all energies since their discovery . throughout this period cosmic rays have always been the source of the highest energy elementary particles known to mankind , and for this reason they have given birth to particle physics .. Please generate the next two sentences of the article

the high energy tail of the spectrum as it is known today corresponds to energies up to 3 @xmath0ev and rates of a few particles per km@xmath1 per century . it is remarkable that the cosmic rays have a quite featureless power law energy spectrum which decreases as approximately the cube of the primary energy . for energies above the few hundred tev the observed flux necessarily requires techniques that take advantage of the extensive air showers that the arriving particles develop as successive secondary particles cascade down into the atmosphere .

Suppose that you have an abstract for a scientific paper: the late - type galaxy ngc 4303 ( m61 ) is one of the most intensively studied barred galaxies in the virgo cluster . its prominent enhanced star formation throughout large areas of the disk can be nicely studied due to its low inclination of about 27 . we present observations of ngc 4303 with the rosat pspc and hri in the soft x - ray ( 0.12.4 kev ) . the bulk of the x - ray emission is located at the nuclear region . it contributes more than 80% to the total observed soft x - ray flux . the extension of the central x - ray source and the @xmath0/@xmath1 ratio point to a low luminous agn ( liner ) with a circumnuclear star - forming region . several separate disk sources can be distinguished with the hri , coinciding spatially with some of the most luminous regions outside the nucleus of ngc 4303 . the total star formation rate amounts to 12 m@xmath2 yr@xmath3 . the x - ray structure follows the distribution of star formation with enhancement at the bar - typical patterns . the best spectral fit consists of a power - law component ( agn and hmxbs ) and a thermal plasma component of hot gas from supernova remnants and superbubbles . the total 0.12.4 kev luminosity of ngc 4303 amounts to 5 erg s@xmath3 , consistent with comparable galaxies , like e.g. ngc 4569 . . And you have already written the first three sentences of the full article: barred galaxies constitute a major fraction of all disc galaxies classified in the optical , more than 50% including strong bars and intermediate morphologies ( sellwood & wilkinson @xcite ) . this fraction increases when also near - infrared images are used for classification , thus underlining the importance for the general understanding of the evolution of galaxies . the non - axisymmetric potential has a strong impact on the gas dynamics and the star formation in barred systems .. Please generate the next two sentences of the article

observations reveal a correlation between the radial abundance gradient and the strength of the bar ( martin & roy @xcite ; friedli et al . @xcite ; martinet & friedli @xcite ) .

Suppose that you have an abstract for a scientific paper: the complex structure of the light curves of _ swift _ grbs has made their interpretation and that of the blast wave caused by the burst , more difficult than in the pre-_swift _ era . we aim to constrain the blast wave parameters : electron energy distribution , @xmath0 , density profile of the circumburst medium , @xmath1 , and the continued energy injection index , @xmath2 . we do so by comparing the observed multi - wavelength light curves and x - ray spectra of a _ swift _ sample to the predictions of the blast wave model . we can successfully interpret all of the bursts in our sample of 10 , except two , within the framework of the blast wave model , and we can estimate with confidence the electron energy distribution index for 6 of the sample . furthermore we identify jet breaks in half of the bursts . a statistical analysis of the distribution of @xmath0 reveals that , even in the most conservative case of least scatter , the values are not consistent with a single , universal value . the values of @xmath1 suggest that the circumburst density profiles are not drawn from only one of the constant density or wind - like media populations . address = mullard space science laboratory , university college london , holmbury st . mary , dorking rh5 6nt , uk , altaddress = astronomical institute , university of amsterdam , kruislaan 403 , 1098sj amsterdam , the netherlands address = nasa postdoctoral program fellow , nsstc , 320 sparkman drive , huntsville , al 35805 , usa address = department of physics and astronomy , university of leicester , university road , leicester le1 7rh , uk address = astronomical institute , university of amsterdam , kruislaan 403 , 1098sj amsterdam , the netherlands . And you have already written the first three sentences of the full article: the afterglow emission of gamma - ray bursts ( grbs ) is generally well described by the blast wave model @xcite . this model details the temporal and spectral behaviour of the emission that is created by external shocks when a collimated ultra - relativistic jet ploughs into the circumburst medium , driving a blast wave ahead of it . the level of collimation , or jet opening angle , has important implications for the energetics of the underlying physical process , progenitor models , and the possible use of grbs as standard candles . the signature of this collimation is an achromatic temporal steepening or ` jet break ' at approximately one day in an otherwise decaying , power - law light curve . since the launch of the _ swift _ satellite it has become clear that this model for grbs can not , in its current form , explain the full complexity of observed light curve features and the lack of observed achromatic temporal breaks .. Please generate the next two sentences of the article

the unexpected features detected , such as steep decays , plateau phases ( e.g. , @xcite ) and a large number of x - ray flares ( e.g. , @xcite ) have revealed the complexity of these sources up to about one day since the initial event , which is yet to be fully understood . these superimposed features also make it difficult to measure the underlying power - law features on which the blast wave model is based , and may lead to misinterpretations of the afterglows . in these proceedings

Suppose that you have an abstract for a scientific paper: we discuss an exact analytical solution of a simplified version of the statistical multifragmentation model with the restriction that the largest fragment size can not exceed the finite volume of the system . a complete analysis of the isobaric partition singularities of this model is done for finite volumes . it is shown that the real part of any simple pole of the isobaric partition defines the free energy of the corresponding state , whereas its imaginary part , depending on the sign , defines the inverse decay / formation time of this state . the developed formalism allows us , for the first time , to exactly define the finite volume analogs of gaseous , liquid and mixed phases of this model from the first principles of statistical mechanics and demonstrate the pitfalls of earlier works . the finite size effects for large fragments and the role of metastable ( unstable ) states are discussed . numbers : 25.70 . pq , 21.65.+f , 24.10 . pa . And you have already written the first three sentences of the full article: a great deal of progress was recently achieved in our understanding of the multifragmentation phenomenon @xcite when an exact analytical solution of a simplified version of the statistical multifragmentation model ( smm ) @xcite was found in refs . an invention of a new powerful mathematical method @xcite , the laplace - fourier transform , allowed us not only to solve this version of smm analytically for finite volumes @xcite , but to find the surface partition and surface entropy of large clusters for a variety of statistical ensembles @xcite . it was shown @xcite that for finite volumes the analysis of the grand canonical partition ( gcp ) of the simplified smm is reduced to the analysis of the simple poles of the corresponding isobaric partition , obtained as a laplace - fourier transform of the gcp .. Please generate the next two sentences of the article

this method opens a principally new possibility to study the nuclear liquid - gas phase transition directly from the partition of finite system and without taking its thermodynamic limit . exactly solvable models with phase transitions play a special role in the statistical physics - they are the benchmarks of our understanding of critical phenomena that occur in more complicated substances .

Suppose that you have an abstract for a scientific paper: a massive star can enter the blue supergiant region either evolving directly from the main - sequence , or evolving from a previous red supergiant stage . the fractions of the blue supergiants having different histories depend on the internal mixing and mass - loss during the red supergiant stage . we study the possibility to use diagnostics based on stellar pulsation to discriminate blue supergiants having different evolution histories . for this purpose we have studied the pulsation property of massive star models calculated with the geneva stellar evolution code for initial masses ranging from 8 to 50m@xmath0 with a solar metallicity of @xmath1 . we have found that radial pulsations are excited in the blue - supergiant region only in the models that had been red - supergiants before . this would provide us with a useful mean to diagnose the history of evolution of each blue - supergiant . at a given effective temperature , much more nonradial pulsations are excited in the model after the red - supergiant stage than in the model evolving towards the red - supergiant . the properties of radial and nonradial pulsations in blue supergiants are discussed . predicted periods are compared with period ranges observed in some @xmath2-cygni variables in the galaxy and ngc300 . we have found that blue supergiant models after the red - supergiant stage roughly agree with observed period ranges in most cases . however , we are left with the puzzle that the predicted surface n / c and n / o ratios seem to be too high compared with those of deneb and rigel . [ firstpage ] stars : evolution stars : early - type stars : mass - loss stars : oscillations stars : rotation stars : abundances . And you have already written the first three sentences of the full article: the post - main - sequence evolution of massive stars depends sensitively on the helium core mass and its ratio to the envelope mass , which in turn depends on still poorly understood phenomena such as mixings in the radiative layers ( core overshooting and rotational mixing ) and wind mass loss . recent evolution models with a solar metallicity of @xmath1 by @xcite indicate that a star with a sufficiently large initial mass undergoes a blue - red - blue ( or blue - loop ) evolution before central helium exhaustion ; i.e. , the star ignites he in the center in the blue supergiant ( bsg ) stage , evolves to the red - supergiant ( rsg ) region , and returns to the blue supergiant ( bsg ) region during core he - burning . the lowest initial - mass for the blue - red - blue evolution depends on the degree of mixing in radiative layers and the strength of wind mass loss .. Please generate the next two sentences of the article

@xcite s results indicate the lower bound to be about 20m@xmath0 . the mass limit is lowered if higher mass - loss rates in the rsg phase is assumed @xcite .

Suppose that you have an abstract for a scientific paper: in this paper , we present methods for image compression on the basis of eigenvalue decomposition of normal matrices . the proposed methods are convenient and self - explanatory , requiring fewer and easier computations as compared to some existing methods . through the proposed techniques , the image is transformed to the space of normal matrices . then , the properties of spectral decomposition are dealt with to obtain compressed images . experimental results are provided to illustrate the validity of the methods . _ keywords : _ image compression , transform , normal matrix , eigenvalue . . And you have already written the first three sentences of the full article: nowadays , digital images and other multimedia files can become very large in size and , therefore , occupy a lot of storage space . in addition , owing to their size , it takes more time to move them from place to place and a larger bandwidth to download and upload them on the internet . so , digital images may pose problems if we regard the storage space as well as file sharing . to tackle this problem , _. Please generate the next two sentences of the article

image compression _ which deals with reducing the size of an image ( or any other multimedia ) file can be used . image compression actually refers to the reduction of the amount of image data ( bits ) required for representing a digital image without causing any major degradation of the image quality . by eliminating redundant data and efficiently optimizing the contents of a file image , provided that as much basic meaning as possible is preserved , image compression techniques , make image files smaller and more feasible to share and store .

Suppose that you have an abstract for a scientific paper: a clear understanding of body force densities due to external electromagnetic fields is necessary to study flow and deformation of materials exposed to the fields . in this paper , we derive an expression for stress in continua with viscous and elastic properties in presence of external , static electric or magnetic fluids . our derivation follows from fundamental thermodynamic principles . we demonstrate the soundness of our results by showing that they reduce to known expressions for newtonian fluids and elastic solids . we point out the extra care to be taken while applying these techniques to permanently polarized or magnetized materials and derive an expression for stress in a ferro - fluid . lastly , we derive expressions for ponderomotive forces in several situations of interest to fluid dynamics and rheology . . And you have already written the first three sentences of the full article: we can study the effect of electromagnetic fields on fluids only if we know the stress induced due to the fields in the fluids . despite its importance , this topic is glossed over in most works on the otherwise well - established subjects of fluid mechanics and classical electrodynamics . the resultant force and torque acting on the body as a whole are calculated but not the density of body force which affects flow and deformation of materials .. Please generate the next two sentences of the article

helmholtz and korteweg first calculated the body force density in a newtonian dielectric fluid in the presence of an electric field , in the late nineteenth century . however , their analysis was criticized by larmor , livens , einstein and laub , who favoured a different expression proposed by lord kelvin .

Suppose that you have an abstract for a scientific paper: laser cooling and trapping are now widely used in atomic physics laboratory . interestingly , cold atoms in optical lattices are now used in advanced research to mimic phenomena in condensed matter physics and also as a test laboratory for the models of these phenomena . it follows then that it is now possible and necessary to advance the atomic physics laboratory by including the use of ultracold atoms in optical lattices for instructional contents of phenomena in condensed matter physics . in this paper , we have proposed how to introduce into the atomic physics laboratory the study of quantum magnetism with cold atoms in a double well optical lattice . in particular , we demonstrates how to compare the theoretical parameters of a spin hamiltonian model with those extracted from spin ordering experiment . . And you have already written the first three sentences of the full article: cold atoms in optical lattices is the application of two formerly distinct aspects of physics : quantum gases from atomic physics @xcite and laser theory from quantum optics @xcite . the optical lattices are artificial crystals of light , that is , a periodic intensity pattern formed by interference of two or more laser beams . as an insight , a pair of these laser beams in opposite directions ( that is , two orthogonal standing waves with orthogonal polarization ) will give a one - dimensional ( 1d ) lattice , two pairs in two opposite directions can be used to create a 2d lattice and a similar three pairs in opposite directions will give a 3d lattice . atoms can be cooled and trapped in these optical lattices .. Please generate the next two sentences of the article

thus in simple form , an optical lattice looks effectively like an egg carton where the atoms , like eggs , can be be arranged one per well to form a crystal of quantum matter @xcite . though the cold atoms in optical lattices was initially used to investigate quantum behaviour such as bloch oscillations , wannier - stark ladders and tunneling phenomena usually associated with crystals in a crystalline solid @xcite , it is the theoretical proposal @xcite and consequent experimental realization @xcite of the superfluid to mott insulator ( sf - mi ) transition which is an important phenomenon in condensed matter physics that has given rise to the possibility of using it as a test laboratory for phenomena in condensed matter physics . the success of the sf - mi transition in turn emanates from the laboratory observation of bose einstein condensation ( bec ) .

Suppose that you have an abstract for a scientific paper: we present a continuum model for the propagation of cracks and fractures in brittle materials . the components of the strain tensor @xmath0 are the fundamental variables . the evolution equations are based on a free energy that reduces to that of linear elasticity for small @xmath0 , and accounts for cracks through energy saturation at large values of @xmath0 . we regularize the model by including terms dependent on gradients of @xmath0 in the free energy . no additional fields are introduced , and then the whole dynamics is perfectly defined . we show that the model is able to reproduce basic facts in fracture physics , like the griffith s dependence of the critical stress as a minus one half power of the crack length . in addition , regularization makes the results insensitive to the numerical mesh used , something not at all trivial in crack modeling . we present and example of the application of the model to predict the growth and curving of cracks in a non - trivial geometrical configuration . . And you have already written the first three sentences of the full article: there are many problems in condensed matter physics and materials science in which the aim is to describe sharp interfaces separating regions with qualitatively different properties . this occurs for instance in solidification , dendritic growth , solid - solid transformations , grain growth , etc . traditionally , two approaches have been followed to tackle these problems . in one of them ,. Please generate the next two sentences of the article

the problem is solved for a fixed position of the interface , and based on this , the expected evolution of the interface in the following time step is calculated , and the process repeated . this method has the practical drawback that the different structure of the interface at each time step makes necessary the full solution of a new problem each time .

Suppose that you have an abstract for a scientific paper: we present a fully nonlinear calculation of the waveform of the gravitational radiation emitted in the fission of a vacuum white hole . at early times , the waveforms agree with close approximation perturbative calculations but they reveal dramatic time and angular dependence in the nonlinear regime . the results pave the way for a subsequent computation of the radiation emitted after a binary black hole merger . . And you have already written the first three sentences of the full article: the omputation of gravitational radiation from the inspiral and merger of binary black holes poses a difficult boundary value problem . in the geometrically simplest and physically most natural treatment , the black holes are modeled by the gravitational collapse of a pair of stars ( or other astrophysical bodies ) . however , this is a challenging hydrodynamic problem which requires simulating a pair of orbiting bodies for a sufficient time to verify a negligible amount of incoming radiation in the initial conditions , then following their subsequent collapse to black holes and finally computing the outgoing radiation in the exterior spacetime .. Please generate the next two sentences of the article

alternatively , in the purely vacuum approach , the individual black holes form from imploding gravitational waves . this avoids hydrodynamical difficulties at the expense of a globally complicated initial value problem .

Suppose that you have an abstract for a scientific paper: using a markov chain monte carlo approach , we find the allowed parameter space of a mssm model with seven free parameters . in this model universality conditions at the gut scale are imposed on the gaugino sector . we require in particular that the relic density of dark matter saturates the value extracted from cosmological measurements assuming a standard cosmological scenario . we characterize the parameter space of the model that satisfies experimental constraints and illustrate the complementarity of the lhc searches , b - physics observables and direct dark matter searches for further probing the parameter space of the model . we also explore the different decay chains expected for the coloured particles that would be produced at lhc . _ _ date : * constraining the mssm with universal gaugino masses and implication for searches at the lhc * + g. blanger@xmath0 , f. boudjema@xmath0 , a. pukhov@xmath1 , r. k. singh@xmath2 + _ 1 ) lapth , univ . de savoie , cnrs , b.p.110 , f-74941 annecy - le - vieux , france + 2 ) skobeltsyn inst . of nuclear physics , moscow state univ . , moscow 119992 , russia + 3 ) institut fr theoretische physik und astrophysik , universitt wrzburg , + d-97074 wrzburg , germany _ + . And you have already written the first three sentences of the full article: among the large number of theoretical models proposed to either solve the hierarchy problem and/or explain dark matter with a new stable particle , the minimal supersymmetric model ( mssm ) remains one of the favourite . supersymmetry not only provides a solution to both these problems but also predicts new physics around the tev scale . the main drawback of the mssm apart from the lack of evidence for supersymmetric particles is the large number of unknown parameters most of which describe the symmetry breaking sector . with the improved sensitivities of dark matter searches in astroparticle experiments @xcite ,. Please generate the next two sentences of the article

the precise determination of the dm relic density from cosmology @xcite , the latest results from the tevatron @xcite and the precision measurements , large regions of the parameter space of the supersymmetric models are being probed . this will continue in the near future with a number of direct and indirect detection experiments improving their sensitivities @xcite and most importantly with the lhc starting to take data .

Suppose that you have an abstract for a scientific paper: we investigate torsional alfvn oscillations of relativistic stars with a global dipole magnetic field , via two - dimensional numerical simulations . we find that a ) there exist two families of quasi - periodic oscillations ( qpos ) with harmonics at integer multiples of the fundamental frequency , b ) the lower - frequency qpo is related to the region of closed field lines , near the equator , while the higher - frequency qpo is generated near the magnetic axis , c ) the qpos are long - lived , d ) for the chosen form of dipolar magnetic field , the frequency ratio of the lower to upper fundamental qpos is @xmath0 , independent of the equilibrium model or of the strength of the magnetic field , and e ) within a representative sample of equations of state and of various magnetar masses , the alfvn qpo frequencies are given by accurate empirical relations that depend only on the compactness of the star and on the magnetic field strength . the lower and upper qpos can be interpreted as corresponding to the edges or turning points of an alfvn continuum , according to the model proposed by levin ( 2007 ) . several of the low - frequency qpos observed in the x - ray tail of sgr 1806 - 20 can readily be identified with the alfvn qpos we compute . in particular , one could identify the 18hz and 30hz observed frequencies with the fundamental lower and upper qpos , correspondingly , while the observed frequencies of 92hz and 150hz are then integer multiples of the fundamental upper qpo frequency ( three times and five times , correspondingly ) . with this identification , we obtain an upper limit on the strength of magnetic field of sgr 1806 - 20 ( if is dominated by a dipolar component ) between @xmath1 and @xmath2 g . furthermore , we show that an identification of the observed frequency of 26hz with the frequency of the fundamental torsional @xmath3 oscillation of the magnetar s crust is compatible with a magnetar mass of about @xmath4 to 1.6@xmath5 and an eos that is very stiff ( if the magnetic field.... And you have already written the first three sentences of the full article: the phenomenon of soft gamma repeaters ( sgrs ) may allow us in the near future to determine fundamental properties of strongly magnetized , compact stars . already , there exist at least two sources in which quasi - periodic oscillations ( qpos ) have been observed in their x - ray tail , following the initial discovery by @xcite , see @xcite for a recent review . the frequency of many of these oscillations is similar to what one would expect for torsional modes of the solid crust of a compact star .. Please generate the next two sentences of the article

this observation is in support of the proposal that sgrs are magnetars ( compact objects with very strong magnetic fields ) @xcite . during an sgr event , torsional oscillations in the solid crust of the star could be excited @xcite , leading to the observed frequencies in the x - ray tail .

Suppose that you have an abstract for a scientific paper: we present results from two observations of the cosmic microwave background ( cmb ) performed from the south pole during the 1993 - 1994 austral summer . each observation employed a 3@xmath0 peak to peak sinusoidal , single difference chop and consisted of a @xmath1 strip on the sky near our sp91 observations . the first observation used a receiver which operates in 3 bands between 38 and 45 ghz ( q - band ) with a fwhm beam which varies from @xmath2 to @xmath3 . the second observation overlapped the first observation and used a receiver which operates in 4 bands between 26 and 36 ghz ( ka - band ) with a fwhm beam which varies from @xmath4 to @xmath5 . the ka - band system has a similar beamsize and frequency coverage as the system used in our sp91 results . significant correlated structure is observed in all bands for each observation . the spectrum of the structure is consistent with a cmb spectrum and is formally inconsistent with diffuse synchrotron and free - free emission at the 5 @xmath6 level . the amplitude of the structure is inconsistent with 20 k interstellar dust ; however , the data do not discriminate against flat or inverted spectrum point sources . the root mean square amplitude ( @xmath7 ) of the combined ( ka+q ) data is @xmath8 @xmath9k for an average window function which has a peak value of @xmath10 at @xmath11 and drops to @xmath12 of the peak value at @xmath13 and @xmath14 . a band power estimate of the cmb power spectrum , @xmath15 , gives @xmath16 . the band power estimates for the individual ka and q - band results are larger than but consistent with the band power estimate of the combined ka - band sp91 results . . And you have already written the first three sentences of the full article: anisotropy measurements of the cosmic microwave background ( cmb ) are a very effective tool for testing and constraining models of cosmic structure formation . with the discovery of large angular scale anisotropy by cobe ( smoot et al . , 1992 ) , there has been an increased interest in characterizing anisotropy on degree angular scales . although all cmb measurements have to overcome a long list of systematic effects and foreground contaminants ( wilkinson , 1994 ) , they have the potential to constrain many of the global parameters of the universe and thus discriminate among the plethora of cosmic structure formation models . over the past six years , we have travelled to the south pole three times to perform these degree scale anisotropy measurements .. Please generate the next two sentences of the article

the results from our 1988 - 89 measurements are detailed in meinhold and lubin , 1991 ( sp89a ) and meinhold et al . , 1993 ( sp89b ) while the results from the 1990 - 91 measurements are detailed in gaier et al . , 1992 ( sp91a ) and schuster et al . , 1993 ( sp91b ) .

Suppose that you have an abstract for a scientific paper: we derive suitable uncertainty relations for characteristics functions of phase and number variables obtained from the weyl form of commutation relations . this is applied to finite - dimensional spin - like systems , which is the case when describing the phase difference between two field modes , as well as to the phase and number of a single - mode field . some contradictions between the product and sums of characteristic functions are noted . . And you have already written the first three sentences of the full article: uncertainty relations are a key item of the quantum theory . this is from fundamental reasons , but also regarding practical applications , since phase - number uncertainty relations are the heart of the quantum limits to the precision of signal detection schemes @xcite . typically , uncertainty relations are expressed in terms of variances and are derived directly from the heisenberg form of commutation relations . however. Please generate the next two sentences of the article

, this approach is not always useful . on the one hand , variance may not be a suitable uncertainty measure . this is specially clear regarding periodic phase - angle variables @xcite . on the other hand ,

Suppose that you have an abstract for a scientific paper: for planar integrable billiards , the eigenstates can be classified with respect to a quantity determined by the quantum numbers . given the quantum numbers as @xmath0 , the index which represents a class is @xmath1 for a natural number , @xmath2 . we show here that the entire tower of states can be generated from an initially given state by application of the operators introduced here . thus , these operators play the same role for billiards as raising and lowering operators in angular momentum algebra . quantum billiards are systems where a single particle is confined inside a boundary on which the eigenfunctions vanish @xcite . one seeks the solutions of the time - independent schrdinger equation , which is the same as the helmholtz equation in the context of general wave phenomena . the solutions of this problem for an arbirarily shaped enclosure is a very challenging open problem , even when we restrict ourselves to two - dimensional cases @xcite . there are some very interesting connections between exactly solvable models and random matrix theories , a summary may be seen in @xcite . the helmholtz operator is separable in certain coordinate systems - for these cases , the solutions can be found @xcite . the non - separable problems for which the classical dynamics is integrable have been recently studied in detail @xcite . although the solutions of these systems have been known , there remain many questions regarding the nature of nodal curves and domains . the nodal domains of the eigenfunctions of the systems for which the schrdinger equation is separable , form a checkerboard pattern @xcite . the number of crossings actually count the number of domains . moreover , the checkerboard patterns are trivially self - similar . counting the nodal domains of non - separable plane polygonal billiards is very difficult in general @xcite . even if we restrict to systems that are classically integrable , the problem poses considerable challenge . progress on this otherwise.... And you have already written the first three sentences of the full article: the solutions of the helmholtz equation for the right isosceles triangle with sidelength , @xmath3 ( chosen for convenience ) are given by @xmath4 @xmath5 . this consists of two terms , each being a product of @xmath6 functions . of course , it can be re - written in a variety of equivalent ways by employing trigonometric identities . with just one term of a product of sine functions ,. Please generate the next two sentences of the article

the nodal lines are straight lines and they form a checkerboard pattern . this would be the case also for a product of any other special function .

Suppose that you have an abstract for a scientific paper: improved wavelength calibrators for high - resolution astrophysical spectrographs will be essential for precision radial velocity ( rv ) detection of earth - like exoplanets and direct observation of cosmological deceleration . the astro - comb is a combination of an octave - spanning femtosecond laser frequency comb and a fabry - prot cavity used to achieve calibrator line spacings that can be resolved by an astrophysical spectrograph . systematic spectral shifts associated with the cavity can be 0.1 - 1 mhz , corresponding to rv errors of 10 - 100 cm / s , due to the dispersive properties of the cavity mirrors over broad spectral widths . although these systematic shifts are very stable , their correction is crucial to high accuracy astrophysical spectroscopy . here , we demonstrate an _ in - situ _ technique to determine the systematic shifts of astro - comb lines due to finite fabry - prot cavity dispersion . the technique is practical for implementation at a telescope - based spectrograph to enable wavelength calibration accuracy better than 10 cm / s . 10 c. lovis , m. mayor , f. pepe , y. alibert , w. benz , f. bouchy , a. c. m. correia , j. laskar , c. mordasini , d. queloz , n. c. santos , s. udry , j .- l . bertaux , and j .- p . sivan , `` an extrasolar planetary system with three neptune - mass planets , '' nature * 441 * , 305309 ( 2006 ) . a. sandage , `` the change of redshift and apparent luminosity of galaxies due to the deceleration of selected expanding universes , '' astrophys . j. * 136 * , 319333 ( 1962 ) . a. loeb , `` direct measurement of cosmological parameters from the cosmic deceleration of selected expanding universes , '' astrophys . j. * 499 * , l111l114 ( 1998 ) . t. udem , r. holzwarth , and t. w. hansch , `` optical frequency metrology , '' nature * 416 * , 233237 ( 2002 ) . m. t. murphy , t. udem , r. holzwarth , a. sizmann , l. pasquini , c. araujo - hauck , h. dekker , s. dodorico , m. fischer , t. w. hnsch.... And you have already written the first three sentences of the full article: high precision wavelength calibrators for astrophysical spectrographs will be key components of new precision radial velocity ( rv ) observations , including the search for earth - like extra - solar planets ( exoplanets ) @xcite and direct observation of cosmological acceleration @xcite . recent work has demonstrated the potential of octave - spanning femtosecond laser frequency combs @xcite ( astro - combs " ) to serve as wavelength calibrators for astrophysical spectrographs providing rv sensitivity down to 1 cm / s @xcite . exoplanet searches place stringent demands upon such calibrators .. Please generate the next two sentences of the article

for example , the rv amplitude of the reflex motion of a solar - mass star induced by an earth - mass planet in an orbit within the habitable zone is about 10 cm / s . the current state of the art astrophysical spectrograph , harps , has demonstrated stellar rv sensitivity @xmath2 cm / s @xcite , largely limited by its thorium argon lamp calibrator @xcite .

Suppose that you have an abstract for a scientific paper: we perform a series of high resolution n - body simulations designed to examine the density profiles of dark matter halos . from 12 simulated halos ranging the mass of @xmath0 ( represented by @xmath1 million particles within the virial radius ) , we find a clear systematic correlation between the halo mass and the slope of the density profile at 1% of the virial radius , in addition to the variations of the slope among halos of the similar mass . more specifically , the slope is @xmath2 , @xmath3 , and @xmath4 for galaxy , group , and cluster mass halos , respectively . while we confirm the earlier simulation results that the inner slope is steeper than the _ universal _ profile originally proposed by navarro , frenk & white , this mass dependence is inconsistent with the several analytical arguments attempting to link the inner slope with the primordial index of the fluctuation spectrum . thus we conclude that the dark matter density profiles , especially in the inner region , are not universal . . And you have already written the first three sentences of the full article: can one recover ( some aspects of ) the initial conditions of the universe from the distribution of galaxies at @xmath5 ? a conventional answer to this question is affirmative , _ provided _ that the effect of a spatial bias is well understood and/or if it does not significantly alter the interpretation of the observed distribution . this consensus underlies the tremendous effort in the past and at present to extract the cosmological implications from the existing and future galaxy redshift surveys .. Please generate the next two sentences of the article

the two - point correlation function @xmath6 is a good example supporting this idea ; on large scales it is trivially related to the primordial spectrum of mass fluctuations , @xmath7 . furthermore the effective power - law index of the two - point correlation function on sufficiently small scales is related to the initial power - law index @xmath8 of @xmath9 as @xmath10 ( e.g. @xcite ; @xcite ; @xcite ) . in other words ,

Suppose that you have an abstract for a scientific paper: we present a comparative study of radiative electroweak + symmetry breaking and conventional standard model breaking , and pose the question whether experiments can distinguish one breaking mode from the other . the importance of the problem lies in the fact that the two breaking modes have very different physical interpretations concerning the mechanism of spontaneous electroweak symmetry breaking and the origin of mass . _ keywords : radiative electroweak symmetry breaking _ + * pacs : 12.38.-t , * + e - mail : fndili@uh.edu . And you have already written the first three sentences of the full article: coleman and weinberg pointed out several years ago [ 1 ] that quantum loops and radiative corrections can play an important role in determining the structure of the vacuum of a quantum field or system of fields and particles . specifically they showed that while a scalar field with mass parameter @xmath0 and classical tree potential is unable to develop a vacuum expectation value ( vev ) and spontaneous symmetry breaking ( ssb ) , such vev and ssb become achievable when we take quantum loops into account . this is particularly so if the scalar field is coupled to a gauge field and dimensional transmutation can occur .. Please generate the next two sentences of the article

the overall conclusion is that an alternative electroweak symmetry breaking ( ewsb ) mechanism exists along side the standard model ewsb mechanism that is based on the classical tree potential : @xmath1 with a non - zero negative mass parameter @xmath2 . the coleman - weinberg alternative model dispenses with the mass parameter @xmath3 in equation ( 1 ) but adds quantum loops or higher order potential terms .

Suppose that you have an abstract for a scientific paper: we present evidence for improvement with tadpole improved clover fermions based on an analysis of the chiral behavior of @xmath0 and the quark condensate . also presented are a comparison of the mass splittings in the baryon octet and decuplet , a calculation of @xmath1 using standard 2-point correlation functions , and the problem of zero modes of the dirac operator . # 1#1 . And you have already written the first three sentences of the full article: with wilson fermions , straightforward calculations of @xmath0 using the 1-loop improved @xmath2 operator fail due to the large mixing with the wrong chirality operators @xcite . since this mixing is an artifact of lattice discretization , one hopes that it can be significantly reduced by improving the action . by comparing results obtained using the wilson and the tadpole improved clover action ( @xmath3 ) on the same quenched gauge lattices ( 170 lattices of size @xmath4 at @xmath5 ) we show that this is indeed the case .. Please generate the next two sentences of the article

[ f : bkw ] shows the wilson and clover data as a function of @xmath6 . for each data set , @xmath0 is written as the sum of two parts @xmath7 the contribution of the diagonal ( the 1-loop tadpole improved @xmath8 ) operator , and the mixing term which is proportional to @xmath9 .

Suppose that you have an abstract for a scientific paper: sports are spontaneous generators of stories . through skill and chance , the script of each game is dynamically written in real time by players acting out possible trajectories allowed by a sport s rules . by properly characterizing a given sport s ecology of ` game stories ' , we are able to capture the sport s capacity for unfolding interesting narratives , in part by contrasting them with random walks . here , we explore the game story space afforded by a data set of 1,310 australian football league ( afl ) score lines . we find that afl games exhibit a continuous spectrum of stories rather than distinct clusters . we show how coarse - graining reveals identifiable motifs ranging from last minute comeback wins to one - sided blowouts . through an extensive comparison with biased random walks , we show that real afl games deliver a broader array of motifs than null models , and we provide consequent insights into the narrative appeal of real games . . And you have already written the first three sentences of the full article: while sports are often analogized to a wide array of other arenas of human activity particularly war well known story lines and elements of sports are conversely invoked to describe other spheres . each game generates a probablistic , rule - based story @xcite , and the stories of games provide a range of motifs which map onto narratives found across the human experience : dominant , one - sided performances ; back - and - forth struggles ; underdog upsets ; and improbable comebacks . as fans , people enjoy watching suspenseful sporting events unscripted stories and following the fortunes of their favorite players and teams @xcite . despite the inherent story - telling nature of sporting contests and notwithstanding the vast statistical analyses surrounding professional sports including the many observations of and departures from randomness @xcite the ecology of game stories remains a largely unexplored , data - rich area @xcite . we are interested in a number of basic questions such as whether the game stories of a sport form a spectrum or a set of relatively isolated clusters , how well models such as random walks fare in reproducing the specific shapes of real game stories , whether or not these stories are compelling to fans , and how different sports compare in the stories afforded by their various rule sets . here , we focus on australian rules football , a high skills game originating in the mid 1800s .. Please generate the next two sentences of the article

we describe australian rules football in brief and then move on to extracting and evaluating the sport s possible game stories . early on , the game evolved into a winter sport quite distinct from other codes such as soccer or rugby while bearing some similarity to gaelic football

Suppose that you have an abstract for a scientific paper: we have analysed the magnitudes , kinematics and positions of a complete sample of 320 pns in the elliptical galaxy ngc 4697 . we show ( i ) that the pns in ngc 4697 do not constitute a single population that is a fair tracer of the distribution of all stars . the radial velocity distributions , mean velocities , and dispersions of bright and faint subsamples differ with high statistical confidence . ( ii ) using the combined data for pns brighter than @xmath0 , we have identified a subpopulation of pns which is azimuthally unmixed and kinematically peculiar , and which thus neither traces the distribution of all stars nor can it be in dynamical equilibrium with the galaxy potential . ( iii ) the planetary nebula luminosity functions ( pnlf ) of two kinematic subsamples in ngc 4697 differ with 99.7% confidence , ruling out a universal pnlf . we estimate that the inferred secondary pn population introduces an uncertainty in the bright cutoff magnitude of @xmath1 mag for this galaxy . we argue that this secondary pn distribution may be associated with a younger , @xmath2 gyr old stellar population , perhaps formed in tidal structures that have now fallen back onto the galaxy , as has previously been suggested for the x - ray point sources in this galaxy , or coming from a more recent merger / accretion with a red galaxy . the use of pns for extragalactic distance determinations is not necessarily compromised , but their use as dynamical tracers of dark halos will require deep observations and careful analysis of large pn samples . . And you have already written the first three sentences of the full article: planetary nebulae ( pns ) have become increasingly important in extragalactic astronomy , for distance determinations via their luminosity function ( lf ) ( * ? ? ? * ; * ? ? ? * ; * ? ? ?. Please generate the next two sentences of the article

* ; * ? ? ? * ; * ? ? ?

Suppose that you have an abstract for a scientific paper: we generalize thouless bandwidth formula to its @xmath0-th moment . we obtain a closed expression in terms of polygamma , zeta and euler numbers . ( * ) lptms , cnrs - facult des sciences dorsay , universit paris sud , 91405 orsay cedex , france . And you have already written the first three sentences of the full article: in a series of stunning papers stretching over almost a decade @xcite thouless obtained a closed expression for the bandwidth of the hofstadter spectrum @xcite in the @xmath1 limit . here the integer @xmath2 stands for the denominator of the rational flux @xmath3 of the magnetic field piercing a unit cell of the square lattice ; the numerator @xmath4 is taken to be @xmath5 ( or equivalently @xmath6 ) is understood to be equal to @xmath5 . ] . let us recall that in the commensurate case where the lattice eigenstates @xmath7 are @xmath2-periodic @xmath8 , with @xmath9 $ ] , the schrodinger equation _ m+1+_m-1 + 2(k_y+m)_m = e_m[eq ] reduces to the @xmath10 secular matrix m_p / q(e , k_x , k_y)= 2 ( k_y)-e & 1 & 0 & & 0 & e^-i q k_x + 1 & 2 ( k_y+)-e & 1 & & 0 & 0 + 0 & 1 & ( ) & & 0 & 0 + & & & & & + 0 & 0 & 0 & & ( ) & 1 + e^i q k_x & 0 & 0 & & 1 & 2 ( k_y+(q-1))-e + acting as [ sharp ] m_p / q(e , k_x , k_y).=0 on the @xmath2-dimensional eigenvector @xmath11 . thanks to the identity ( m_p / q(e , k_x , k_y))=(m_p / q(e,0,0))-2 ( -1)^q ( ( q k_x)-1 + ( q k_y)-1 ) , the schrodinger equation @xmath12 rewrites @xcite as [ eigen ] ( m_p / q(e,0,0))=2 ( -1)^q ( ( q k_x)-1 + ( q k_y)-1 ) the polynomial b_p. Please generate the next two sentences of the article

/ q(e)=-_j=0^[q2]a_p / q(2j)e^2j materializes in @xmath13 [ sososimple](m_p / q(e,0,0))+4(-1)^q=(-1)^q e^qb_p / q(1/e ) so that eq . ( [ eigen ] ) becomes @xmath14 the @xmath15 s ( with @xmath16 ) are related to the kreft coefficients @xcite : one obtains ( see @xcite ) @xmath17 with building blocks 4 ^ 2()=e^-ik_y(1-e^2 i ( k+1 ) p q)e^ik_y(1-e^-2 i ( k+1 ) p q)=_p / q(k)expressed in terms of _ p / q(k)=e^-ik_y(1-e^2 i ( k+1 ) p q ) and its complex conjugate.how to get an explicit expression for these coefficients is explained in kreft s paper .