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Suppose that you have an abstract for a scientific paper: we generalize the quasilocal definition of the stress energy tensor of einstein gravity to the case of third order lovelock gravity , by introducing the surface terms that make the action well - defined . we also introduce the boundary counterterm that removes the divergences of the action and the conserved quantities of the solutions of third order lovelock gravity with zero curvature boundary at constant @xmath0 and @xmath1 . then , we compute the charged rotating solutions of this theory in @xmath2 dimensions with a complete set of allowed rotation parameters . these charged rotating solutions present black hole solutions with two inner and outer event horizons , extreme black holes or naked singularities provided the parameters of the solutions are chosen suitable . we compute temperature , entropy , charge , electric potential , mass and angular momenta of the black hole solutions , and find that these quantities satisfy the first law of thermodynamics . we find a smarr - type formula and perform a stability analysis by computing the heat capacity and the determinant of hessian matrix of mass with respect to its thermodynamic variables in both the canonical and the grand - canonical ensembles , and show that the system is thermally stable . this is commensurate with the fact that there is no hawking - page phase transition for black objects with zero curvature horizon . . And you have already written the first three sentences of the full article: in four dimensions , the einstein tensor is the only conserved symmetric tensor that depends on the metric and its derivatives up to second order . however for spacetimes possessing more than four dimensions , as assumed in both string theory and brane world cosmology , this is not the case . in string theory , extra dimensions are a theoretical necessity since superstring theory requires a ten - dimensional spacetime to be consistent from the quantum point of view , while in brane world cosmology matter and gauge interactions are localized on a 3-brane , embedded into a higher dimensional spacetime in which gravity propagates throughout the whole of spacetime .. Please generate the next two sentences of the article

the most natural extension of general relativity in higher dimensional spacetimes with the assumption of einstein that the left hand side of the field equations is the most general symmetric conserved tensor containing no more than two derivatives of the metric is lovelock theory . lovelock @xcite found the most general symmetric conserved tensor satisfying this property .

Suppose that you have an abstract for a scientific paper: red clump giant stars can be used as distance indicators to trace the mass distribution of the galactic bar . we use rcg stars from 44 bulge fields from the ogle - ii microlensing collaboration database to constrain analytic tri - axial models for the galactic bar . we find the bar major axis is oriented at an angle of @xmath0 @xmath1 to the sun - galactic centre line - of - sight . the ratio of semi - major and semi - minor bar axis scale lengths in the galactic plane @xmath2 , and vertical bar scale length @xmath3 , is @xmath4 , suggesting a slightly more prolate bar structure than the working model of @xcite which gives the scale length ratios as @xmath5 . galaxy : bulge - galaxy : centre - galaxy : structure . And you have already written the first three sentences of the full article: it is now generally accepted that the galactic bulge is a tri - axial , bar - like structure . observational evidence for a bar has arisen from several sources , such as the study of gas kinematics ( e.g. @xcite ) , surface brightness ( e.g. @xcite ) , star counts ( e.g. @xcite ) and microlensing ( e.g. @xcite ) ; see @xcite for a review . observational data have been used to constrain dynamical models of the galaxy .. Please generate the next two sentences of the article

@xcite used the cobe - dirbe multi - wavelength observations of the galactic centre @xcite to constrain several analytic bar models . @xcite used optical observations of red clump giant ( rcg ) stars to constrain theoretical bar models .

Suppose that you have an abstract for a scientific paper: studies of limits on active - sterile neutrino mixing derived from big bang nucleosynthesis considerations are extended to consider the dependance of these constraints on the primordial deuterium abundance . this study is motivated by recent measurements of d / h in quasar absorption systems , which at present yield discordant results . limits on active - sterile mixing are somewhat relaxed for high d / h . for low d / h ( @xmath0 ) , no active - sterile neutrino mixing is allowed by currently popular upper limits on the primordial @xmath1he abundance @xmath2 . for such low primordial d / h values , the observational inference of active - sterile neutrino mixing by upcoming solar neutrino experiments would imply that @xmath2 has been systematically underestimated , unless there is new physics not included in standard bbn . upper limits on the abundance of @xmath1he produced in big bang nucleosynthesis ( bbn ) have been used to limit mixing between active ( @xmath3 , @xmath4 , or @xmath5 ) and sterile ( @xmath6 , no standard model interactions ) neutrinos @xcite . in this paper , we point out and discuss how these constraints are dependant on the adopted primordial deuterium abundance . previous limits on sterile neutrino mixing have assumed a value for the lower bound on the baryon - to - photon ratio @xmath7 derived from interstellar medium and solar system measurements of deuterium ( d ) and @xmath8he , and models of chemical and galactic evolution . recent measurements of d / h in quasar absorption systems ( qas ) have yielded discordant values of this ratio , some higher than previously derived ranges @xcite , and some lower @xcite . several factors make an investigation of the primordial d / h dependance of bbn constraints on active - sterile neutrino mixing timely : the discordant qas measurements of d / h ; the fact that future solar neutrino experiments may be able to distinguish and identify @xmath9 mixing @xcite ; and the use of sterile neutrinos in schemes for neutrino masses and.... And you have already written the first three sentences of the full article: this work was supported by the national science foundation through nsf grant phy-9503384 , and by a nasa theory grant . m. rugers and c. j. hogan , report astro - ph/9603084 , 1996 ( unpublished ) ; m. rugers and c. j. hogan , astrophys . j. lett . * 459 * , l1 ( 1996 ) ; e. j. wampler _ et al . _ ,. Please generate the next two sentences of the article

( to be published ) ; r. f. carswell _ et al . _ , mon . not

Suppose that you have an abstract for a scientific paper: we present simple analytical approximations to matter - effect corrected effective neutrino mixing - angles and effective mass - squared - differences . the expressions clarify the dependence of oscillation probabilities in matter to the mixing angles and mass - squared - differences in vacuum , and are useful for analyzing long - baseline neutrino oscillation experiments . . And you have already written the first three sentences of the full article: the discovery of neutrino masses and mixings through solar @xcite , atmospheric @xcite , and reactor @xcite neutrino oscillation experiments has provided new clues to solving the mysteries of the standard model . flavor mixing in the lepton - sector , together with the well - known mixing in the quark - sector , may lead to a new understanding of what ` flavor ' is , why there are three generations of fermions , and where the quark- and lepton - mass hierarchies come from . cp violation in the neutrino - sector could potentially be large enough to account for the matter - antimatter asymmetry in the universe @xcite . due to these possibilities ,. Please generate the next two sentences of the article

several long - baseline ( lbl ) neutrino oscillation experiments are in progress @xcite with many more being proposed @xcite for the purpose of better determining the neutrino masses and mixing parameters . since the neutrino beams of lbl experiments necessarily traverse the earth , the understanding of matter effects @xcite is crucial in extracting the masses and mixing parameters in vacuum from the measured oscillation probabilities in matter . the calculation of matter effects requires the diagonalization of the effective hamiltonian in matter , which is an energy- and matter - density - dependent @xmath0 matrix .

Suppose that you have an abstract for a scientific paper: the classic hii region m17 is one of the best studied across the electromagnetic spectrum . we present sensitive , high angular resolution observations made with the jansky very large array ( jvla ) at 4.96 and 8.46 ghz that reveal the presence of 38 compact radio sources , in addition to the well known hypercompact cometary hii region m17 uc1 . for this last source we find that its spectral index of value @xmath01 is due to a gradient in opacity across its face . of the 38 compact radio sources detected , 19 have stellar counterparts detected in the infrared , optical , or x - rays . finally , we discuss the nature of the radio emission from the massive binary system cen 1a and 1b , concluding that both are most probably non - thermal emitters , although the first is strongly time variable and the second is steady . . And you have already written the first three sentences of the full article: the centimeter continuum radiation from classic hii regions is dominated by strong free - free emission from the extended ionized gas present there . however , when observed with the high angular resolution provided by an interferometer , the extended emission is filtered out and one starts to detect compact sub - arcsecond sources of various natures ( see garay et al . 1987 ; churchwell et al . 1987 ; felli et al . 1993 ; zapata et al .. Please generate the next two sentences of the article

2004 for the case of orion a ) . the brightest of these sources are the hypercompact ( hc ) hii regions , that trace the ionized gas produced by young ob stars still embedded in dense molecular gas ( e.g. kurtz 2005 ; lizano 2008 ) .

Suppose that you have an abstract for a scientific paper: several puzzling aspects of interplay of the experimental lattice distortion and the the magnetic properties of four narrow @xmath0-band perovskite oxides ( ytio@xmath1 , latio@xmath1 , yvo@xmath1 , and lavo@xmath1 ) are clarified using results of first - principles electronic structure calculations . first , we derive parameters of the effective hubbard - type hamiltonian for the isolated @xmath0 bands using newly developed downfolding method for the kinetic - energy part and a hybrid approach , based on the combination of the random - phase approximation and the constraint local - density approximation , for the screened coulomb interaction part . apart form the above - mentioned approximation , the procedure of constructing the model hamiltonian is totally parameter - free . the results are discussed in terms of the wannier functions localized around transition - metal sites . the obtained hamiltonian was solved using a number of techniques , including the mean - field hartree - fock ( hf ) approximation , the second - order perturbation theory for the correlation energy , and a variational superexchange theory , which takes into account the multiplet structure of the atomic states . we argue that the crystal distortion has a profound effect not only on the values of the crystal - field ( cf ) splitting , but also on the behavior of transfer integrals and even the screened coulomb interactions . even though the cf splitting is not particularly large to quench the orbital degrees of freedom , the crystal distortion imposes a severe constraint on the form of the possible orbital states , which favor the formation of the experimentally observed magnetic structures in ytio@xmath1 , yvo@xmath1 , and lavo@xmath1 even at the level of mean - field hf approximation . it is remarkable that for all three compounds , the main results of all - electron calculations can be successfully reproduced in our minimal model derived for the isolated @xmath0 bands . we confirm that such an agreement is only.... And you have already written the first three sentences of the full article: the transition - metal perovskite oxides @xmath2o@xmath1 ( with @xmath3@xmath4 y , la , or other trivalent rare - earth ion , and @xmath5@xmath4 ti or v ) are regarded as some of the key materials for understanding the strong coupling among spin , orbital , and lattice degrees of freedom in correlated electron systems.@xcite according to the electronic structure calculations in the local - density approximation ( lda ) , all these compounds can be classified as `` @xmath0 systems '' , as all of them have a common transition - metal @xmath0-band , located near the fermi level , which is well separated from the oxygen-@xmath6 band and a hybrid transition - metal @xmath7 and either y(@xmath8 ) or la(@xmath9 ) band , located correspondingly in the lower- and upper - part of the spectrum ( fig . [ fig.dossummary ] ) . the number of electrons that are donated by each ti and v site into the @xmath0-band is correspondingly one and two .. Please generate the next two sentences of the article

these electrons are subjected to the strong intraatomic coulomb repulsion , which is not properly treated by lda and requires some considerable improvement of this approximation , which currently processes in the direction of merging lda with various model approaches for the strongly - correlated systems.@xcite nevertheless , lda continues play an important role for these systems as it naturally incorporates into the model analysis the effects of the lattice distortion , and does it formally without any adjustable parameters . although the origin of the lattice distortion in the @xmath0 perovskite oxides is not fully understood , is is definitely strong and exhibits an appreciable material - dependence , which can be seen even visually in fig .

Suppose that you have an abstract for a scientific paper: we present a modular , extensible likelihood framework for spectroscopic inference based on synthetic model spectra . the subtraction of an imperfect model from a continuously sampled spectrum introduces covariance between adjacent datapoints ( pixels ) into the residual spectrum . for the high signal - to - noise data with large spectral range that is commonly employed in stellar astrophysics , that covariant structure can lead to dramatically underestimated parameter uncertainties ( and , in some cases , biases ) . we construct a likelihood function that accounts for the structure of the covariance matrix , utilizing the machinery of gaussian process kernels . this framework specifically address the common problem of mismatches in model spectral line strengths ( with respect to data ) due to intrinsic model imperfections ( e.g. , in the atomic / molecular databases or opacity prescriptions ) by developing a novel local covariance kernel formalism that identifies and self - consistently downweights pathological spectral line outliers . " by fitting many spectra in a hierarchical manner , these local kernels provide a mechanism to learn about and build data - driven corrections to synthetic spectral libraries . an open - source software implementation of this approach is available at http://iancze.github.io/starfish , including a sophisticated probabilistic scheme for spectral interpolation when using model libraries that are sparsely sampled in the stellar parameters . we demonstrate some salient features of the framework by fitting the high resolution @xmath0-band spectrum of wasp-14 , an f5 dwarf with a transiting exoplanet , and the moderate resolution @xmath1-band spectrum of gliese 51 , an m5 field dwarf . . And you have already written the first three sentences of the full article: all astronomers recognize that spectroscopy offers a wealth of information that can help characterize the properties of the observing target . in the context of stellar astrophysics , spectroscopy plays many fundamental roles . the relative strengths and widths of stellar absorption lines provide access to physical properties like effective temperature ( @xmath2 ) and surface gravity ( @xmath3 ) , enabling model comparisons in the hertzsprung - russell diagram to estimate the masses and ages so crucial to understanding stellar evolution , as well as individual elemental abundances or the collective metallicity " ( typically parameterized as @xmath4}$ ] ) , facilitating studies of the chemical hallmarks of different stellar populations . with sufficient resolution. Please generate the next two sentences of the article

, a spectrum also conveys information about rotation ( @xmath5 ) and kinematics ( e.g. , association with a cluster or companion through the radial velocity , @xmath6 ) . while many fields benefit from such spectroscopic measurements , they are of acute interest to the exoplanet community .

Suppose that you have an abstract for a scientific paper: we investigate the sedimentation equilibrium of a charge stabilized colloidal suspension in the regime of low ionic strength . we analyze the asymptotic behaviour of the density profiles on the basis of a simple poisson boltzmann theory and show that the effective mass we can deduce from the barometric law corresponds to the actual mass of the colloidal particles , contrary to previous studies . # 1 . And you have already written the first three sentences of the full article: under the action of gravity a colloidal suspension sediments to form a stratified fluid . the equilibrium density profile of the colloidal particles results from the balance between the gravitational force and thermodynamic forces as derived from the free energy of the system . the density profiles usually exhibits a dense layer of colloidal particles at the bottom of the container above which a light cloud of colloidal particles floats . in this last regime ,. Please generate the next two sentences of the article

the density of particles is small enough to treat the fluid as an ideal gas . under the reasonable assumption that density gradients can be neglected , the equilibrium colloidal density obey the well known barometric law : @xmath0 here , @xmath1 denotes the density profile of the colloidal particles , @xmath2 is the altitude and @xmath3 is the gravitational length where @xmath4 is the inverse temperature , @xmath5 is the buoyant mass of a colloidal particle and @xmath6 the intensity of the gravitational field .

Suppose that you have an abstract for a scientific paper: we present high resolution @xmath0-band polarized intensity ( @xmath1 ; fwhm = @xmath2 : 14 au ) and @xmath3-band imaging data ( fwhm @xmath4 : 15 au ) of the circumstellar disk around the weak - lined t tauri star pds 70 in centaurus at a radial distance of 28 au ( @xmath5 ) up to 210 au ( 1.@xmath65 ) . in both images , a giant inner gap is clearly resolved for the first time , and the radius of the gap is @xmath770 au . our data show that the geometric center of the disk shifts by @xmath76 au toward the minor axis . we confirm that the brown dwarf companion candidate to the north of pds 70 is a background star based on its proper motion . as a result of sed fitting by monte carlo radiative transfer modeling , we infer the existence of an optically thick inner disk at a few au . combining our observations and modeling , we classify the disk of pds 70 as a pre - transitional disk . furthermore , based on the analysis of @xmath3-band imaging data , we put an upper limit mass of companions at @xmath730 to @xmath750@xmath8 within the gap . taking account of the presence of the large and sharp gap , we suggest that the gap could be formed by dynamical interactions of sub - stellar companions or multiple unseen giant planets in the gap . . And you have already written the first three sentences of the full article: protoplanetary disks are believed to be the birthplaces of planets ( e.g. , * ? ? ? * ) ; hence , understanding the evolution of these disks guides our understanding of the process of planet formation . disks which have substantial infrared excesses but reduced fluxes at wavelengths @xmath920 @xmath10 m , i.e. , transitional disks @xcite , could be related to the early phases of planet formation ( see a recent review of * ? ? ? * ) and are therefore particularly important for understanding how , where , and when planets form . for many transitional disks , partial inner holes or partial gaps. Please generate the next two sentences of the article

have been directly resolved by interferometry at ( sub)millimeter wavelengths ( e.g. , * ? ? ? * ; * ? ? ?

Suppose that you have an abstract for a scientific paper: we comment on some recent , yet unpublished results concerning instabilities in complex systems and their applications . in particular , we briefly describe main observations during extensive computer simulations of two lattice nonequilibrium models . one exhibits robust and efficient processes of pattern recognition under synaptic coherent activity ; the second example exhibits interesting critical behavior and simulates nucleation and spinodal decomposition processes in driven fluids . _ key words _ : neural networks , driven lattice gas , spinodal decomposition , nonequilibrium phase transitions , celular automata . _ pacs _ : 05.50.+q , 05.70.fh , 05-70.ln , 64.60.qb , 75.40.mg . And you have already written the first three sentences of the full article: nature may be viewed as a collection of _ complex systems _ @xcite . consequently , a principal question is how these systems , which typically consist of many simple interacting units , develop qualitatively new and high - level kinds of organization . this is the problem of connecting the microscopics of constituents with the coherent structures that characterize organisms and communities .. Please generate the next two sentences of the article

it may often be assumed that the fundamental laws of physics , such as hamilton and maxwell equations , are individual properties of the units . still , it is only very rare that the origin and form of natural phenomena can be inferred from basic laws .

Suppose that you have an abstract for a scientific paper: we compute the reidemeister torsion of the complement of a twist knot in @xmath0 and that of the 3-manifold obtained by a dehn surgery on a twist knot . . And you have already written the first three sentences of the full article: in a recent paper kitano @xcite gives a formula for the reidemeister torsion of the 3-manifold obtained by a dehn surgery on the figure eight knot . in this paper we generalize his result to all twist knots . specifically , we will compute the reidemeister torsion of the complement of a twist knot in @xmath0 and that of the 3-manifold obtained by a dehn surgery on a twist knot .. Please generate the next two sentences of the article

let @xmath1 be the link in figure 1 , where @xmath2 denote the numbers of half twists in the boxes . positive ( resp .

Suppose that you have an abstract for a scientific paper: we study the continuum scaling limit of the critical ising magnetization in two dimensions . we prove the existence of subsequential limits , discuss connections with the scaling limit of critical fk clusters , and describe work in progress of the author with c. garban and c.m . newman . * keywords : * continuum scaling limit , critical and near / off - critical ising model , euclidean field theory , fk clusters . * ams 2000 subject classification : * 82b27 , 60k35 , 82b43 , 60d05 . . And you have already written the first three sentences of the full article: the ising model in @xmath0 dimensions is perhaps the most studied statistical mechanical model and has a special place in the theory of critical phenomena since the groundbreaking work of onsager @xcite . its scaling limit at or near the critical point is recognized to give rise to euclidean ( quantum ) field theories . in particular , at the critical point , the lattice magnetization field should converge , in the scaling limit , to a euclidean random field @xmath1 corresponding to the simplest reflection - positive conformal field theory @xcite . as such , there have been a variety of representations in terms of free fermion fields @xcite and explicit formulas for correlation functions ( see , e.g. , @xcite and references therein ) . in @xcite , c.m . newman and the present author introduced a representation of @xmath1 in terms of random geometric objects associated with schramm - loewner evolutions ( sles ) @xcite ( see also @xcite ) and conformal loop ensembles ( cles ) @xcite namely , a gas ( or random process ) of continuum loops and associated clusters and ( renormalized ) area measures .. Please generate the next two sentences of the article

the purpose of the present paper is twofold , as we now explain . first of all , we provide a detailed proof of the existence of subsequential limits of the lattice magnetization field as a square integrable random variable and a random generalized function ( theorem [ thm : subseqential - limits ] ) following the ideas presented in @xcite .

Suppose that you have an abstract for a scientific paper: we present temporal and spectral results from monitoring with the rossi x - ray timing explorer ( rxte ) in 1998 and 1999 . we concentrate on the long term evolution of the hard state timing properties , comparing it to the 1996 soft state evolution . this leads to the following results : 1 . the hard and soft state time lag spectra are very similar , 2 . during state transitions , the lags in the 110hz range increase by more than an order of magnitude , 3 . in the hard state itself , flaring events can be seen the temporal and spectral evolution during the flare of 1998 july identifies it as a `` failed state transition '' . during ( failed ) state transitions , the time lag spectra and the power spectra change predominantly in the 110hz range . we suggest that this additional variability is produced in ejected coronal material disrupting the synchrotron radiation emitting outflows present in the hard state . . And you have already written the first three sentences of the full article: galactic black hole candidates ( bhc ) are predominantly found in two states : the hard state , in which the x - ray spectrum is a comptonization spectrum emerging from a hot electron cloud with a typical electron temperature of @xmath0150kev @xcite , and the soft state , in which the x - ray spectrum is thermal with a characteristic temperature of @xmath1kev to which a steep power - law is added ( * ? ? ? * ; * ? ? ? * and references therein ) .. Please generate the next two sentences of the article

the x - ray states are also known to be associated with radio states ( see , e.g. , * ? ? ? * for a review ) . the canonical bhc stays predominantly in the hard state , and only occasionally transits into the soft state for a few months ( * ? ? ?

Suppose that you have an abstract for a scientific paper: we explicitly determine all magnetic curves corresponding to the killing magnetic fields on the 3-dimensional euclidean space . * keywords and phrases . * killing magnetic field , lorentz force , magnetic curve . * 2010 msc : * 53a04 , 65d17 . And you have already written the first three sentences of the full article: the geodesic flow on a riemannian manifold represents the extremals of the least action principle , namely it is determined by the motion of a certain physical system in the manifold . it is known that the geodesic equations are second order non - linear differential equations and they usually appear in the form of euler - lagrange equations of motion . magnetic curves generalize geodesics . in physics ,. Please generate the next two sentences of the article

such a curve represents a trajectory of a charged particle moving on the manifold under the action of the magnetic field . let @xmath0 be an @xmath1-dimensional riemannian manifold .

Suppose that you have an abstract for a scientific paper: this paper analyses the numerical solution of a class of non - linear schrdinger equations by galerkin finite elements in space and a mass- and energy conserving variant of the crank - nicolson method due to sanz - serna in time . the novel aspects of the analysis are the incorporation of weak and strong disorder potentials , the consideration of some general class of non - linearities , and the proof of convergence with rates in @xmath0 under moderate regularity assumptions that are compatible with discontinuous potentials . for sufficiently smooth potentials , the rates are optimal without any coupling condition between the time step size and the spatial mesh width . crank - nicolson galerkin approximations to nonlinear schrdinger equations with disorder potentials + patrick henning , daniel peterseim + . And you have already written the first three sentences of the full article: this paper is devoted to nonlinear schrdinger equations ( nls ) of the form @xmath1 here , @xmath2 is a complex valued function , @xmath3 is a possibly rough / discontinuous potential and @xmath4 is a smooth function ( in terms of the density @xmath5 ) that describes the nonlinearity . a common example is the cubic nonlinearity given by @xmath6 , for @xmath7 , for which the equation is known as the gross - pitaevskii equation modeling for instance the dynamics of bose - einstein condensates in a potential trap @xcite . in this paper we study galerkin approximations of the nls using a finite element space discretization to account for missing regularity due to a possibly discontinuous potential and we use a crank - nicolson time discretization to conserve two important invariants of the nls , namely the mass and the energy. Please generate the next two sentences of the article

. we aim at deriving rate - explicit a priori error estimates and the influence of rough potentials on these rates . the list of references to numerical approaches for solving the nls ( both time - dependent and stationary ) is long and includes @xcite and the references therein .

Suppose that you have an abstract for a scientific paper: it was recently realized @xcite that a model constructed from a lee - wick type scalar field theory yields , at the level of homogeneous and isotropic background cosmology , a bouncing cosmology . however , bouncing cosmologies induced by pressure - less matter are in general unstable to the addition of relativistic matter ( i.e. radiation ) . here we study the possibility of obtaining a bouncing cosmology if we add radiation coupled to the lee - wick scalar field . this coupling in principle would allow the energy to flow from radiation to matter , thus providing a drain for the radiation energy . however , we find that it takes an extremely unlikely fine tuning of the initial phases of the field configurations for a sufficient amount of radiative energy to flow into matter . for general initial conditions , the evolution leads to a singularity rather than a smooth bounce . . And you have already written the first three sentences of the full article: both standard @xcite and inflationary cosmology @xcite suffer from the initial singularity problem and hence can not yield complete descriptions of the very early universe . if one were able to construct a non - singular bouncing cosmology , this problem would obviously disappear . however , in order to have a chance to obtain such a non - singular cosmology , one must either go beyond einstein gravity as a theory of space - time ( see e.g. @xcite for an early construction ) , or else one must make use of matter which violates the null energy condition " ( see @xcite for a review of both types of approaches ) .. Please generate the next two sentences of the article

interest in non - singular bouncing cosmologies has increased with the realization that they can lead to alternatives to inflationary cosmology as a theory for the origin of structure in the universe . a specific scenario which can arise at the level of homogeneous and isotropic cosmology is the matter bounce " paradigm which is based on the realization @xcite that vacuum fluctuations which exit the hubble radius during a matter - dominated contracting phase evolve into a scale - invariant spectrum of curvature perturbations on super - hubble scales before the bounce .

Suppose that you have an abstract for a scientific paper: the ground state of the four - chain heisenberg ladder model is numerically investigated . hidden - order correlations suitable for the system are introduced and calculated with an emphasis on the spatially isotropic point , where a corresponding material exists . the existence of a long - range hidden correlation indicates formation of a short - range rvb state in the case of the antiferromagnetic inter - chain coupling . a transition between the phase of the ferromagnetic inter - chain coupling and that of the antiferromagnetic one is discussed . keywords : hidden correlation , ladder model , resonating valence bond , haldane phase . And you have already written the first three sentences of the full article: in recent years , considerable attention has been devoted to ground - state properties of low - dimensional quantum systems . the interest was greatly stimulated by the discovery of the high - temperature superconductivity,@xcite and by subsequent studies which revealed the importance of the cuo@xmath0 plane of high-@xmath1 materials . however , complete understanding of the high-@xmath1 mechanism still appears to be beyond our reach .. Please generate the next two sentences of the article

a possible new approach to the high-@xmath1 mechanism was provided by a recent experiment@xcite on the novel material sr@xmath2cu@xmath3o@xmath4 . this material has periodic line defects in the cuo@xmath0 plane , and thus is composed of ladders with @xmath5 legs interacting weakly with each other .

Suppose that you have an abstract for a scientific paper: the dynamical mean - field theory ( dmft ) is a widely applicable approximation scheme for the investigation of correlated quantum many - particle systems on a lattice , e.g. , electrons in solids and cold atoms in optical lattices . in particular , the combination of the dmft with conventional methods for the calculation of electronic band structures has led to a powerful numerical approach which allows one to explore the properties of correlated materials . in this introductory article we discuss the foundations of the dmft , derive the underlying self - consistency equations , and present several applications which have provided important insights into the properties of correlated matter . [ avella : vollhardt ] . And you have already written the first three sentences of the full article: already in 1937 , at the outset of modern solid state physics , de boer and verwey @xcite drew attention to the surprising properties of materials with incompletely filled 3@xmath0-bands . this observation prompted mott and peierls @xcite to discuss the interaction between the electrons . ever since transition metal oxides ( tmos ) were investigated intensively @xcite .. Please generate the next two sentences of the article

it is now well - known that in many materials with partially filled electron shells , such as the 3@xmath0 transition metals v and ni and their oxides , or 4@xmath1 rare - earth metals such as ce , electrons occupy narrow orbitals . the spatial confinement enhances the effect of the coulomb interaction between the electrons , making them `` strongly correlated '' .

Suppose that you have an abstract for a scientific paper: the relationship between the clustering of dark matter and that of luminous matter is often described using the bias parameter . here , we provide a new method to probe the bias of intermediate to high - redshift radio continuum sources for which no redshift information is available . we matched radio sources from the faint images of the radio sky at twenty centimetres ( first ) survey data to their optical counterparts in the sloan digital sky survey ( sdss ) to obtain photometric redshifts for the matched radio sources . we then use the publicly available semi - empirical simulation of extragalactic radio continuum sources ( s@xmath0 ) to infer the redshift distribution for all first sources and estimate the redshift distribution of unmatched sources by subtracting the matched distribution from the distribution of all sources . we infer that the majority of unmatched sources are at higher redshifts than the optically matched sources and demonstrate how the angular scales of the angular two - point correlation function can be used to probe different redshift ranges . we compare the angular clustering of radio sources with that expected for dark matter and estimate the bias of different samples . [ firstpage ] cosmology : methods : data analysis methods : statistical astronomical bases : miscellaneous galaxies : redshift surveys galaxies : large - scale structure of universe . . And you have already written the first three sentences of the full article: current and future radio continuum surveys typically probe redshifts out to @xmath1 and often cover a significant fraction of the sky . the large volumes accessible in these surveys provide a probe of the large - scale structure and thus can be utilised to test cosmological models . one of the most common approaches to investigate the large - scale distribution of cosmological objects is the two - point angular correlation function ( acf ) which quantifies the projected clustering of galaxies on the plane of the sky . to gain information on the three dimensional distribution of galaxies and their evolution with time , the redshift distribution of the sample needs to be known .. Please generate the next two sentences of the article

however , in general , redshifts can not be obtained from radio continuum surveys since the spectra do not show emission or absorption line features . one way to gain redshift information of these radio sources is to match them to their optical counterparts for which the redshifts are known .

Suppose that you have an abstract for a scientific paper: an eutactic star , in a @xmath0-dimensional space , is a set of @xmath1 vectors which can be viewed as the projection of @xmath1 orthogonal vectors in a @xmath1-dimensional space . by adequately associating a star of vectors to a particular sea urchin we propose that a measure of the eutacticity of the star constitutes a measure of the regularity of the sea urchin . then we study changes of regularity ( eutacticity ) in a macroevolutive and taxonomic level of sea urchins belonging to the echinoidea class . an analysis considering changes through geological time suggests a high degree of regularity in the shape of these organisms through their evolution . rare deviations from regularity measured in holasteroida order are discussed . eutactic stars , bilateral symmetry , regularity , sea urchins . And you have already written the first three sentences of the full article: this work is dealing with regularity , which is a property with deep implications in organisms . from the biological point of view regularity has been related with radial symmetry , and irregularity with bilateral symmetry @xcite . the heuristic value of radial and bilateral symmetry in biology account for taxonomic issues , however , symmetry as well as disruption symmetry have been an empirical and intuitive approach accounting for structural properties in organisms @xcite . from a mathematical point of view. Please generate the next two sentences of the article

, the property of regularity of a geometric form has not been formalized . based in previous results by @xcite , we hypothesize that _ eutacticity _ provides a measure of regularity based in the following argument .

Suppose that you have an abstract for a scientific paper: a few simply - stated rules govern the entanglement patterns that can occur in mutually unbiased basis sets ( mubs ) , and constrain the combinations of such patterns that can coexist ( , the stoichiometry ) in full complements of ( @xmath0 ) mubs . we consider hilbert spaces of prime power dimension ( as realized by systems of @xmath1 prime - state particles , or _ qupits _ ) , where full complements are known to exist , and we assume only that mubs are eigenbases of generalized pauli operators , without using a particular construction . the general rules include the following : 1 ) in any mub , a particular qupit appears either in a pure state , or totally entangled , and 2 ) in any full mub complement , each qupit is pure in ( @xmath2 ) bases ( not necessarily the same ones ) , and totally entangled in the remaining ( @xmath3 ) . it follows that the maximum number of product bases is @xmath2 , and when this number is realized , all remaining ( @xmath3 ) bases in the complement are characterized by the total entanglement of every qupit . this `` standard distribution '' is inescapable for two qupits ( of any @xmath4 ) , where only product and generalized bell bases are admissible mub types . this and the following results generalize previous results for qubits @xcite and qutrits @xcite , drawing particularly upon . with three qupits there are three mub types , and a number of combinations ( @xmath5 ) are possible in full complements . with @xmath6 , there are 6 mub types for @xmath7 , but new mub types become possible with larger @xmath4 , and these are essential to realizing full complements . with this example , we argue that new mub types , showing new entanglement characteristics , should enter with every step in @xmath1 , and when @xmath1 is a prime plus 1 , also at critical @xmath4 values , @xmath8 . such mubs should play critical roles in filling complements . . And you have already written the first three sentences of the full article: mutually unbiased basis sets are known to provide an optimal basis for quantum tomography @xcite , to play key roles in quantum cryptography @xcite , and to be instrumental in solving the mean king problem in prime power dimensions @xcite . the generalized pauli operators associated with mub s include the stabilizers of quantum error correcting codes @xcite , and serve as entanglement witnesses @xcite for the mub states . of interest for the foundations of quantum physics , the mub concept sharpens the concept of complementarity @xcite , and raises the question of existence in composite dimensions . an excellent comprehensive review of mubs has recently appeared @xcite .. Please generate the next two sentences of the article

we deal here with hilbert spaces of prime power dimensions ( @xmath9 ) , where @xmath10 mubs are known to exist @xcite . this is both the largest possible number , and also the number required for a complete operator basis ( in representing the density matrix , for example ) .

Suppose that you have an abstract for a scientific paper: the properties of randomly evolving special trees having defined and analyzed already in two earlier papers ( arxiv : cond - mat/0205650 and arxiv : cond - mat/0211092 ) have been investigated in the case when the continuous time parameter converges to infinity . equations for generating functions of the number of nodes and end - nodes in a stationary ( i.e. infinitely old ) tree have been derived . in order to solve exactly these equations we have chosen three different distributions for the number of new nodes @xmath0 produced by one dying node . by using appropriate method we have calculated step - by - step the probabilities of finding @xmath1 nodes as well as end - nodes in a stationary random tree . analyzing the results of numerical calculations we have observed that the qualitative properties of stationary random trees depend hardly on the character of distribution of @xmath0 . the conclusion to be correct that in the evolution process the formation of a rod - like stationary tree is much more probable than the formation of a tree with many branches . we have established that the probability of finding @xmath2 nodes in a stationary tree depends sensitively on the average value of @xmath0 and has a maximum the location of which is increasing with @xmath2 but remains always smaller than unity . this is also true for the end - nodes . * pacs : 02.50.-r , 02.50.ey , 05.40.-a * . And you have already written the first three sentences of the full article: in previous two papers @xcite , @xcite we defined and analyzed random processes with continuous time parameter describing the evolution of special trees consisting of _ living and dead nodes _ connected by _ lines_. it seems to be appropriate to repeat briefly the characteristic features of the evolution process . the initial state @xmath3 of the tree corresponds to a single living node called _ root _ which at the end of its life is capable of producing @xmath4 new living nodes , and after that it becomes immediately dead . if @xmath5 then the new nodes are promptly connected to the dead node and each of them _ independently of the others _ can evolve further like a root .. Please generate the next two sentences of the article

the random evolution of trees with continuous time parameter has not been investigated intensively recently . the main interest since the late 1990s has been focussed on the study of non - equilibrium networks @xcite occurring in common real world . the evolution mechanism of trees with living and dead nodes may be useful in some of biological systems where the branching processes are dominant . in what follows , we will use notations applied in @xcite and @xcite .

Suppose that you have an abstract for a scientific paper: galactic and extragalactic abundance studies of h ii regions , planetary nebulae , and supernova remnants are compiled and their implications briefly reviewed . galaxy global metallicity appears to be related directly to total mass and morphology , while gradient slopes are uncorrelated with these parameters , although barred spirals tend to have flatter profiles than non - barred spirals . n / o behavior is consistent with primary , then secondary , production of n as metallicity increases , and empirical evidence for a metallicity - sensitive c yield is seen . metallicity - invariant primary production mechanisms are suggested for s , ne , ar , and o. . And you have already written the first three sentences of the full article: abundance measurements of c , n , o , ne , s , and ar in galactic and extragalactic h ii regions , planetary nebulae , and supernova remnants represent a major source of information about elemental levels in the interstellar media of spiral disks . measured from the ground in most cases , the strengths of the numerous emission features produced by these objects can be converted in a straightforward way to ionic and elemental abundances . when the abundances for nebular objects within a single galaxy are compiled , several correlations are shown to exist either between interstellar metallicity and galactocentric distance , i.e. an abundance gradient , or between pairs of abundance ratios . since the former is directly linked to matter distribution and star formation rates , and the latter depends on the imf and stellar yields , complete abundance profile information for a galactic disk provides important constraints on galactic chemical evolution models and hence our global understanding of how elemental composition changes within a galaxy as a function of time and location .. Please generate the next two sentences of the article

the purpose of this review is to provide a summary of extant data pertaining to nebular abundance profiles in disk galaxies along with brief interpretations . readers are referred to other papers in this volume for more detailed theoretical explorations of abundance gradients .

Suppose that you have an abstract for a scientific paper: we show the utility of the weak value amplification to observe the quantum interference between two close lying atomic coherent states in a post - selected atomic cat state , produced in a system of @xmath0 identical two - level atoms weakly interacting with a single photon field . through the observation of the negative parts of the wigner distribution of the post - selected atomic cat state , we find that the post - selected atomic cat state becomes more nonclassical when the post - selected polarization state of the single photon field tends toward becoming orthogonal to its pre - selected state . we show that the small phase shift in the post - selected atomic cat state can be amplified via measuring the peak shift of its phase distribution when the post - selected state of the single photon field is nearly orthogonal to its pre - selected state . we find that the amplification factor of 15 [ 5 ] can be obtained for a sample of 10 [ 100 ] atoms . this effectively provides us with a method to discriminate two close lying states on the bloch sphere . we discuss possible experimental implementation of the scheme , and conclude with a discussion of the fisher information . + keywords : weak value amplification , the atomic cat state , the wigner distribution , the phase distribution , interference , the fisher information . And you have already written the first three sentences of the full article: the weak value amplification of the observables is finding increasing number of applications in the study of a variety of physical systems @xcite . although originally formulated for quantum systems , many past and current applications include applications to classical light beams . for example the first observation of the weak value amplification was in the context of a gaussian beam propagating through a birefringent medium @xcite .. Please generate the next two sentences of the article

other important applications of weak value amplification include observation of spin hall effect of light @xcite , goos - hnchen shifts and various generalizations @xcite , angular shifts of light beams @xcite , enhancement of interferometric results @xcite . weak value amplification has been used to measure the state of polarization of light beam on poincare sphere using optical vortex beams @xcite .

Suppose that you have an abstract for a scientific paper: we investigate the temperature and energy on holographic screens for 4-dimensional black holes with the entropic force idea proposed by verlinde . we find that the `` unruh - verlinde temperature '' is equal to the hawking temperature on the horizon and can be considered as a generalized hawking temperature on the holographic screen outside the horizons . the energy on the holographic screen is not the black hole mass @xmath0 but the reduced mass @xmath1 , which is related to the black hole parameters . with the replacement of the black hole mass @xmath0 by the reduced mass @xmath1 , the entropic force can be written as @xmath2 , which could be tested by experiments . . And you have already written the first three sentences of the full article: recently , verlinde @xcite presented a remarkable new idea that gravity can be explained as an entropic force caused by the information changes when a material body moves away from the holographic screen . this idea implies that gravity is not fundamental . with the holographic principle and the equipartition law of energy , verlinde showed that newton s law of gravitation can arise naturally and unavoidably in a theory in which space is emergent through a holographic scenario , and a relativistic generalization leads to the einstein equations .. Please generate the next two sentences of the article

in fact , the similar idea can be traced back to sakharov s work @xcite . on the other side , using the equipartition law of energy for the horizon degrees of freedom together with the thermodynamic relation @xmath3 , padmanabhan also obtained the newton s law of gravity @xcite . subsequently , with the idea of entropic force , some applications have been carried out .

Suppose that you have an abstract for a scientific paper: a graph with a trivial automorphism group is said to be _ rigid_. wright proved @xcite that for @xmath0 a random graph @xmath1 is rigid whp . it is not hard to see that this lower bound is sharp and for @xmath2 with positive probability @xmath3 is nontrivial . we show that in the sparser case @xmath4 , it holds whp that @xmath5 s @xmath6-core is rigid . we conclude that for all @xmath7 , a graph in @xmath8 is reconstrutible whp . in addition this yields for @xmath9 a canonical labeling algorithm that almost surely runs in polynomial time with @xmath10 error rate . this extends the range for which such an algorithm is currently known @xcite . . And you have already written the first three sentences of the full article: it is a truth universally acknowledged , that random objects are asymmetric . it was shown by wright @xcite that for @xmath11 a random @xmath8 graph has , whp , a trivial automorphism group . he actually worked with the @xmath12 model , but the reduction to @xmath8 is well - known and follows easily from the chernoff bound .. Please generate the next two sentences of the article

also , a graph and its complement clearly have the same automorphism group , so we can restrict ourselves to the range @xmath13 . wright s bound is tight , since a graph @xmath5 of slightly smaller density is likely to have isolated vertices , which can be swapped by a @xmath5-automorphism . this paper concerns the range of smaller @xmath7 by showing that for @xmath14 whp all of @xmath5 s automorphisms are essentially trivial . here is our main result : theoremmaintheorem[thm : maintheorem ] let @xmath15 be a @xmath8 graph with @xmath16 . then whp its @xmath6-core has a trivial automorphism group .

Suppose that you have an abstract for a scientific paper: we discuss the classical cosmological tests for a large class of frw type models driven by a decaying vacuum energy density . analytic expressions for the lookback time , age of the universe , luminosity distance , angular diameter , and galaxy number counts versus redshift are derived and their meaning discussed in detail . it is found that the standard frw results are significantly altered , showing that such tests may constrain the physical parameters of these models which are also in agreement to the accelerated expansion suggested by the latest sne type ia observations . . And you have already written the first three sentences of the full article: recent measurements from some type ia supernovae ( sne ) at intermediate and high redshifts ( perlmutter et al . 1999 , riess et al . 1998 ) indicate that the bulk of energy in the universe is repulsive and appears like a quintessence " component , that is , an unknown form of dark energy ( in addition to the ordinary cdm matter ) probably of primordial origin ( see turner 2000 for a review ) . together with the observations of cmb anisotropies ( de bernardis 2000 ) , such results seem to provide an important piece of information connecting an early inflationary stage with the astronomical observations . this state of affairs has stimulated the interest for more general models containing an extra component describing this dark energy , and simultaneously accounting for the present accelerated stage of the universe .. Please generate the next two sentences of the article

however , the absence of a convincing evidence on the nature of the dark component gave origin to an intense debate and mainly to theoretical speculations . a possible list of old and new candidates for quintessence " now include : \(i ) a decaying vacuum energy density , or a time varying @xmath0-term ( zer and taha 1987 , freese at al .

Suppose that you have an abstract for a scientific paper: the use of polarized beams enhance the possibility of the precision measurements at the international linear collider ( ilc ) @xcite . in order to preserve the degree of polarization during beam transport spin rotators are included in the current tdr ilc lattice @xcite . in this report some advantages of using a combined spin rotator / spin flipper section are discussed . a few possible lattice designs of spin flipper developed at desy in 2012 are presented . . And you have already written the first three sentences of the full article: the importance of beam polarization for the ilc experiments can be illustrated by fact that the effective luminosity is increasing by approximately @xmath0 in the case of both beam polarized @xcite . furthermore a suitable combination of polarized electron and positron beams suppresses significantly unwanted background processes and enhances signal rates . there are two important aspects which should be taken into account for polarized beams .. Please generate the next two sentences of the article

the first one is a delivery of polarized beams from the source to the interaction point . the spin transport for the different areas of the ilc were already studied @xcite and the installation of spin rotators before and after damping ring was recommended .

Suppose that you have an abstract for a scientific paper: we present [ fe / h ] abundance results that involve a sample of stars with a wide range in luminosity from luminous giants to stars near the turnoff in a globular cluster . our sample of 25 stars in m71 includes 10 giant stars more luminous than the rhb , 3 horizontal branch stars , 9 giant stars less luminous than the rhb , and 3 stars near the turnoff . we analyzed both fe i and fe ii lines in high dispersion spectra observed with hires at the w. m. keck observatory . we find that the [ fe / h ] abundances from both fe i and fe ii lines agree with each other and with earlier determinations . also the [ fe / h ] obtained from fe i and fe ii lines is constant within the rather small uncertainties for this group of stars over the full range in @xmath0 and luminosity , suggesting that nlte effects are negligible in our iron abundance determination . in this globular cluster , there is no difference among the mean [ fe / h ] of giant stars located at or above the rhb , rhb stars , giant stars located below the rhb and stars near the turnoff . . And you have already written the first three sentences of the full article: abundance determinations of stars in galactic globular clusters can provide valuable information about important astrophysical processes such as stellar evolution , stellar structure , galactic chemical evolution and the formation of the milky way . surface stellar abundances of c , n , o , and often na , mg , and al are found to be variable among red giants within a globular cluster . the physical process responsible of these star - to - star element variations is still uncertain ( see * ? ? ?. Please generate the next two sentences of the article

* paper i ) . of particular importance to the present study are the results of @xcite , who found that [ fe / h ] among m92 subgiants is a factor of two smaller than [ fe / h ] from red giants in the same cluster @xcite .

Suppose that you have an abstract for a scientific paper: in recent work , we have proposed an approach to test data generation ( tdg ) of imperative bytecode by _ partial evaluation _ ( pe ) of clp which consists in two phases : ( 1 ) the bytecode program is first transformed into an equivalent clp program by means of interpretive compilation by pe , ( 2 ) a second pe is performed in order to supervise the generation of test - cases by execution of the clp decompiled program . the main advantages of tdgby pe include flexibility to handle new coverage criteria , the possibility to obtain test - case generators and its simplicity to be implemented . the approach in principle can be directly applied for tdgof any imperative language . however , when one tries to apply it to a declarative language like prolog , we have found as a main difficulty the generation of test - cases which cover the more complex control flow of prolog . essentially , the problem is that an intrinsic feature of pe is that it only computes non - failing derivations while in tdgfor prolog it is essential to generate test - cases associated to failing computations . basically , we propose to transform the original prolog program into an equivalent prolog program with _ explicit failure _ by partially evaluating a prolog interpreter which captures failing derivations w.r.t . the input program . another issue that we discuss in the paper is that , while in the case of bytecode the underlying constraint domain only manipulates integers , in prolog it should properly handle the symbolic data manipulated by the program . the resulting scheme is of interest for bringing the advantages which are inherent in tdgby pe to the field of logic programming . . And you have already written the first three sentences of the full article: test data generation ( tdg ) aims at automatically generating test - cases for interesting test _ coverage criteria_. the coverage criteria measure how well the program is exercised by a test suite . examples of coverage criteria are : _ statement coverage _ which requires that each line of the code is executed ; _ path coverage _ which requires that every possible trace through a given part of the code is executed ; etc .. Please generate the next two sentences of the article

there are a wide variety of approaches to tdg(see @xcite for a survey ) . our work focuses on _ glass - box _

Suppose that you have an abstract for a scientific paper: a lifshitz scalar with the dynamical critical exponent @xmath0 obtains scale - invariant , super - horizon field fluctuations without the need of an inflationary era . since this mechanism is due to the special scaling of the lifshitz scalar and persists in the presence of unsuppressed self - couplings , the resulting fluctuation spectrum can deviate from a gaussian distribution . we study the non - gaussian nature of the lifshitz scalar s intrinsic field fluctuations , and show that primordial curvature perturbations sourced from such field fluctuations can have large non - gaussianity of order @xmath1 , which will be detected by upcoming cmb observations . we compute the bispectrum and trispectrum of the fluctuations , and discuss their configurations in momentum space . in particular , the bispectrum is found to take various shapes , including the local , equilateral , and orthogonal shapes . intriguingly , all integrals in the in - in formalism can be performed analytically . = 1 . And you have already written the first three sentences of the full article: hoava - lifshitz gravity @xcite is attracting much attention as one of candidates for the theory of quantum gravity because of its power - counting renormalizability , which is realized by the lifshitz scaling @xmath2 with the dynamical critical exponent @xmath3 in the ultraviolet ( uv ) . there are many attempts to investigate properties and implications of this theory @xcite . it is natural to suppose that not only gravitational fields but also other fields exhibit the same lifshitz scaling in the uv .. Please generate the next two sentences of the article

even if they classically have different scalings , quantum corrections should render them to have the same scaling . a lifshitz scalar with @xmath4 can obtain scale - invariant , super - horizon field fluctuations even without inflation @xcite , thus can source the primordial curvature perturbations through mechanisms such as the curvaton scenario @xcite or the modulated decay @xcite .

Suppose that you have an abstract for a scientific paper: in the present work we introduce a generalized lattice - gas model to study the multilayer adsorption of interacting polyatomics on heterogeneous surfaces . using an approximation in the spirit of the well - known brunauer emmet teller ( bet ) model , a new theoretical isotherm is obtained in one- and two - dimensional lattices and compared with monte carlo simulation . in addition , we use the bet approach to analyze these isotherms and to estimate the monolayer volume . in all cases , we found that the use of the bet equation leads to an underestimate of the true monolayer capacity . however , significant compensation effects were observed for heterogeneous surfaces and attractive lateral interactions . , , equilibrium thermodynamics and statistical mechanics , surface thermodynamics , adsorption isotherms , monte carlo simulations . And you have already written the first three sentences of the full article: the theoretical description of adsorption is a long - standing complex problem in surface science that presently does not have a general solution @xcite . in 1918 langmuir derived the monolayer adsorption isotherm kinetically for gas monoatomic molecules adsorbed on the homogeneous surface of adsorbents without attractions among the adsorbed molecules @xcite . later , some theories have been proposed to describe multilayer adsorption in equilibrium @xcite . among them , the one of brunauer - emmett - teller ( bet ) @xcite and the one of frenkel - halsey - hill @xcite are the simplest which provide the basis to construct more elaborate approaches .. Please generate the next two sentences of the article

those more elaborate analytic approaches take into account lateral interactions between the admolecules , differences between the energy of the first and upper layers , surface energetic heterogeneity and so forth . these leading models have played an important role in the characterization of solid surfaces by means of gas adsorption .

Suppose that you have an abstract for a scientific paper: high - frequency observations of the tailed radio galaxies ic310 , ngc1265 , 3c129 , and 3c465 have been performed with the effelsberg 100-m telescope . for the radio galaxies ic310 , ngc1265 and 3c465 , radio data obtained at low frequencies with the westerbork synthesis radio telescope are also available . these new radio data allow us to map the extended structure of the radio galaxies and obtain spectral and polarization information in the outermost regions . the multi - frequency spectra were used to study the synchrotron ageing of relativistic electrons with increasing distance from the active nucleus . we found that the spectrum in each radio galaxy progressively steepens with distance , and at each location it is steeper at high frequencies . the spectra are fitted by models involving synchrotron energy losses and the critical frequency is obtained at increasing distance from the core . assuming that the magnetic field is the equipartition value , we obtain the radiating electron lifetimes and consequently their drift velocities . our results imply the existence of reacceleration processes or bulk motions along the tails . the polarization data at 10.6 ghz give information on the intrinsic degree of polarized flux and the orientation of the magnetic field . we find that the polarization percentage increases along the tails , reflecting an increase of the degree of ordering of the magnetic field . the magnetic field in the tails is longitudinal . 27a 40l 0 1 . And you have already written the first three sentences of the full article: the study of extended radio galaxies in clusters of galaxies is important to understand the evolution of radio sources . in particular , the low - brightness lobes are at a late stage of evolution and are typically confined by the intergalactic medium , therefore synchrotron losses dominate in these regions . studies of extended radio sources often suffer from limitations of the high - resolution interferometric observations , which can properly map the low - brightness regions only at low frequencies ( 610 327 mhz or lower ) . on the other hand , information on the relativistic particle ageing and on the polarization behaviour of the extended low - brightness regions is only obtained with multiple frequencies .. Please generate the next two sentences of the article

the effelsberg 100-m radio telescope is at present the best available instrument to map the outermost regions of extended radio galaxies with good angular resolution , overcoming the problem of the lack of short spacings ( see e.g. andernach et al . 1992 and mack et al .

Suppose that you have an abstract for a scientific paper: we statistically reconstruct a three - dimensional model of a tungsten - silver composite from an experimental two - dimensional image . the effective young s modulus ( @xmath0 ) of the model is computed in the temperature range 251060@xmath1c using a finite element method . the results are in good agreement with experimental data . as a test case , we have reconstructed the microstructure and computed the moduli of the overlapping sphere model . the reconstructed and overlapping sphere models are examples of bi - continuous ( non - particulate ) media . the computed moduli of the models are not generally in good agreement with the predictions of the self - consistent method . we have also evaluated three - point variational bounds on the young s moduli of the models using the results of beran , molyneux , milton and phan thien . the measured data were close to the upper bound if the properties of the two phases were similar ( @xmath2 ) . = -27.0 mm = -30 mm * keywords : * structure - property relationships ; microstructures ( a ) ; inhomogeneous material ( b ) ; finite elements ( c ) ; probability and statistics ( c ) . . And you have already written the first three sentences of the full article: predicting the macroscopic properties of composite or porous materials with random microstructures is an important problem in a range of fields @xcite . there now exist large - scale computational methods for calculating the properties of composites given a digital representation of their microstructure ; eg . permeability @xcite , conductivity @xcite and elastic moduli @xcite .. Please generate the next two sentences of the article

a critical problem is obtaining an accurate three - dimensional ( 3d ) description of this microstructure @xcite . for particular materials it may be possible to simulate microstructure formation from first principles .

Suppose that you have an abstract for a scientific paper: the cfrs 1452 + 52 field has been deeply imaged with the infrared space observatory ( iso ) using isocam through the lw3 filter ( 12 - 18@xmath0 m ) . careful data analysis and comparison to deep optical and radio data have allowed us to generate a catalog of 78 15 @xmath0 sources with both radio and optical identifications . they are redder and lie at higher redshift than i - band selected galaxies , with most of them being star - forming galaxies . + we have considered the galaxies detected at radio and 15@xmath0 m wavelengths which potentially include all strong and heavily extincted starbursts , up to z=1 . spectral energy distributions ( sed ) for each of the sources have been derived using deep radio , mid - ir , near - ir , optical and uv photometry . the sources were then spectrally classified by comparing to seds of well known nearby galaxies . by deriving their fir luminosities by interpolation , we can estimate their star formation rate ( sfr ) in a way which does not depend sensitively on the extinction . 75% ( -40% , + 10% ) of the star formation at z@xmath1 1 is related to ir emission and the global extinction is in the range @xmath2=0.5 0.85 . while heavily extincted starbursts , with sfr in excess of 100 m@xmath3 constitute less than a percent of all galaxies , they contribute about 18% of the sfr density out to z=1 . their morphologies range from s0 to sab , and more than a third are interacting systems . + the sfr derived by fir fluxes is likely to be @xmath4 2.9 times higher than those previously estimated from uv fluxes . the derived stellar mass formed since the redshift of 1 could be too high when compared to the present day stellar mass density . this might be due to an imf in distant star - forming galaxies different from the solar neighborhood one , or to an underestimate of the local stellar mass density . . And you have already written the first three sentences of the full article: the 2800 and [ oii]3727 emission line luminosity densities have decreased by a factor of @xmath4 10 from z = 1 to the present day ( lilly et al . 1996 ; hammer et al . this has led madau et al .. Please generate the next two sentences of the article

( 1996 , 1998 ) to suggest that the cosmic star formation density has decreased by the same factor within that redshift interval , and that most of the stars seen now were formed during the first half of the universe s existence . the uv emission from galaxies is produced by a complex mix of short and moderately long - lived stars , the latter ( late b and a0 stars ) contributing more at longer uv wavelengths .

Suppose that you have an abstract for a scientific paper: quantitative models of sunspot and starspot decay predict the timescale of magnetic diffusion and may yield important constraints in stellar dynamo models . motivated by recent measurements of starspot lifetimes , we investigate the disintegration of a magnetic flux tube by nonlinear diffusion . previous theoretical studies are extended by considering two physically motivated functional forms for the nonlinear diffusion coefficient @xmath0 : an inverse power - law dependence @xmath1 and a step - function dependence of @xmath0 on the magnetic field magnitude @xmath2 . analytical self - similar solutions are presented for the power - law case , including solutions exhibiting `` superfast '' diffusion . for the step - function case , the heat - balance integral method yields approximate solutions , valid for moderately suppressed diffusion in the spot . the accuracy of the resulting solutions is confirmed numerically , using a method which provides an accurate description of long - time evolution by imposing boundary conditions at infinite distance from the spot . the new models may allow insight into differences and similarities between sunspots and starspots . . And you have already written the first three sentences of the full article: a great deal of effort has gone into observing and analyzing disintegration of sunspots ( and starspots ) . the sunspot decay is usually characterized by the rate of decrease of the sunspot area @xmath3 , and numerous observations appear to be consistent with a parabolic decay law , with @xmath4 a decreasing quadratic function of time @xmath5 . early theories invoked turbulent diffusion of the magnetic field within the spot to model the observed rate of decay , yet such models predicted a linear decay law , corresponding to a constant area decay rate @xmath6 @xcite . in order to explain a parabolic decay. Please generate the next two sentences of the article

, @xcite developed a model of sunspot disintegration by turbulent `` erosion '' of penumbral boundaries , which occurs when bits of magnetic field are sliced away from the edge of a sunspot and swept to the supergranular cell boundaries by supergranular flows @xcite . a key feature of the erosion model is that the turbulent diffusivity , associated with the flows , is suppressed within the spot .

Suppose that you have an abstract for a scientific paper: we present a simple dynamical model for describing trading interactions between agents in a social network by considering only two dynamical variables , namely money and goods or services , that are assumed conserved over the whole time span of the agents trading transactions . a key feature of the model is that agent - to - agent transactions are governed by the price in units of money per goods , which is dynamically changing , and by a trust variable , which is related to the trading history of each agent . all agents are able to sell or buy , and the decision to do either has to do with the level of trust the buyer has in the seller , the price of the goods and the amount of money and goods at the disposal of the buyer . here we show the results of extensive numerical calculations under various initial conditions in a random network of agents and compare the results with the available related data . in most cases the agreement between the model results and real data turns out to be fairly good , which allow us to draw some general conclusions as how different trading strategies could affect the distribution of wealth in different kinds of societies . + : social networks , agent - based model , wealth distribution , nonlinear dynamical systems , price effects , trust , reputation + . And you have already written the first three sentences of the full article: in human societies social life consists of the flow and exchange of norms , values , ideas , goods as well as other social and cultural resources , which are channeled through a network of interconnections . in all the social relations between people _ trust _ is a fundamental component @xcite , such that the quality of the dyadic relationships reflects the level of trust between them . from the personal perspective social networks can be considered structured in a series of layers whose sizes are determined by person s cognitive constraints and frequency and quality of interactions @xcite , which in turn correlate closely with the level of trust that the dyad of individuals share . as one moves from the inner to the outer layers of an individual s social network , emotional closeness diminishes , as does trust . despite its key role in economics , sociology , and social psychology ,. Please generate the next two sentences of the article

the detailed psychological and social mechanisms that underpin trust remain open . in order to provide a systematic framework to understand the role of trust , one needs to create metrics or quantifiable measures as well as models for describing plausible mechanisms producing complex emergent effects due to social interactions of the people in an interconnected societal structure .

Suppose that you have an abstract for a scientific paper: the full sky cosmic microwave background polarization field can be decomposed into ` electric ' and ` magnetic ' components . working in harmonic space we construct window functions that allow clean separation of the electric and magnetic modes from observations over only a portion of the sky . we explicitly demonstrate the method for azimuthally symmetric patches , but also present it in a form in principle applicable to arbitrarily - shaped patches . from the window functions we obtain variables that allow for robust estimation of the magnetic component without risk of contamination from the probably much larger electric signal . the variables have a very simple noise properties , and further analysis using them should be no harder than analysing the temperature field . for an azimuthally - symmetric patch , such as that obtained from survey missions when the galactic region is removed , the exactly - separated variables are fast to compute . we estimate the magnetic signal that could be detected by the planck satellite in the absence of extra - galactic foregrounds . we also discuss the sensitivity of future experiments to tensor modes in the presence of a magnetic signal generated by weak lensing , and give lossless methods for analysing the electric polarization field in the case that the magnetic component is negligible . a series of appendices review the spin weight formalism and give recursion relations for fast computation of the spin - weighted spherical harmonics and their inner products over azimuthally - symmetric patches of the sphere . a further appendix discusses the statistics of weak signal detection . . And you have already written the first three sentences of the full article: observations of fluctuations in the temperature of the cosmic microwave background ( cmb ) are now providing us with a direct view of the primordial inhomogeneities in the universe . the power spectrum of temperature fluctuations yields a wealth of information on the nature of the primordial perturbations , and the values of the cosmological parameters . mapping the polarization of the cosmic microwave sky is an important next step , offering a great deal of complementary information , especially regarding the character of the primordial inhomogeneities @xcite .. Please generate the next two sentences of the article

one of the most interesting questions to resolve is whether the primordial perturbations possessed a tensor ( gravitational wave ) component , as predicted by simple inflationary models . here , polarization measurements offer a unique probe @xcite .

Suppose that you have an abstract for a scientific paper: the presence of inhomogeneities modifies the cosmic distances through the gravitational lensing effect , and , indirectly , must affect the main cosmological tests . assuming that the dark energy is a smooth component , the simplest way to account for the influence of clustering is to suppose that the average evolution of the expanding universe is governed by the total matter - energy density whereas the focusing of light is only affected by a fraction of the total matter density quantified by the @xmath0 dyer - roeder parameter . by using two different samples of sne type ia data , the @xmath1 and @xmath0 parameters are constrained by applying the zeldovich - kantowski - dyer - roeder ( zkdr ) luminosity distance redshift relation for a flat ( @xmath2cdm ) model . a @xmath3-analysis using the 115 sne ia data of astier _ et al . _ sample ( 2006 ) constrains the density parameter to be @xmath4(@xmath5 ) while the @xmath0 parameter is weakly limited ( all the values @xmath6 $ ] are allowed even at 1@xmath7 ) . however , a similar analysis based the 182 sne ia data of riess _ et al . _ ( 2007 ) constrains the pair of parameters to be @xmath8 and @xmath9 ( @xmath5 ) . basically , this occurs because the riess _ et al . _ sample extends to appreciably higher redshifts . as a general result , even considering the existence of inhomogeneities as described by the smoothness @xmath0 parameter , the einstein - de sitter model is ruled out by the two samples with a high degree of statistical confidence ( @xmath10 and @xmath11 , respectively ) . the inhomogeneous hubble - sandage diagram discussed here highlight the necessity of the dark energy , and a transition deceleration / accelerating phase at @xmath12 is also required . 0.5 cm . And you have already written the first three sentences of the full article: the hubble - sandage diagram for type ia supernovae ( hereafter sneia ) , as measured by the supernova cosmology project@xcite and the high - z supernova search team@xcite , provided the first evidence that the present universe is undergoing a phase of accelerating expansion driven by an exotic component with negative pressure ( in addition to the cold dark matter ) , usually called dark energy . the idea of a dark energy - dominated universe is a direct consequence of a convergence of independent observational results , and constitutes one of the greatest challenges for our current understanding of fundamental physics@xcite . among a number of possibilities to describe this dark energy component , the simplest and most theoretically appealing way is by means of a cosmological constant @xmath2 , which acts on the einstein field equations as an isotropic and homogeneous source with a constant equation of state , @xmath13 . although cosmological scenarios with a @xmath2 term might explain most of the current astronomical observations , from the theoretical viewpoint they are plagued with at least a fundamental problem , namely , it is really difficult to reconcile the small value of the vacuum energy density required by observations ( @xmath14 ) with estimates from quantum field theories ranging from 50 - 120 orders of magnitude larger@xcite .. Please generate the next two sentences of the article

this problem sometimes called the cosmological constant problem ( pcc ) has inspired many authors to propose decaying @xmath2 models@xcite and other alternative approaches for describing dark energy@xcite . nevertheless , the present cosmic concordance model ( ccm ) which is supported by all the existing observations is a flat @xmath2cdm cosmology with a matter fraction of @xmath15 and a vacuum energy contribution of @xmath16@xcite . on the other hand ,

Suppose that you have an abstract for a scientific paper: the latest structure function results , as presented at the ichep98 conference , are reviewed . a brief introduction to the formalism and the status of global analyses of parton distributions is given . the review focuses on three experimental areas : fixed - target results and their constraints on the parton densities at high @xmath0 ; spin structure and spin parton densities as well as the status of the associated sum rules ; hera results on the dynamics of @xmath1 at low @xmath2 , charm and @xmath3 as well as the measurement and interpretation of the high-@xmath4 neutral and charged current cross - sections . _ plenary talk presented at the xxix ichep98 conference , _ _ vancouver , july 1998 . _ _ slides are available from _ _ http://www-zeus.desy.de/conferences98/#ichep98 _ 17.0 cm -1.0 in -42pt plus 2 mm minus 2 mm epsf = cmr8 1.5pt # 1#2#3#4#1 * # 2 * , # 3 ( # 4 ) glas - ppe/980716@xmath5 december 1998 . And you have already written the first three sentences of the full article: the differential cross - section @xmath6 for a lepton ( @xmath7 , @xmath8 ) with four - momentum @xmath9 scattering off a nucleon with four - momentum @xmath10 can be expressed as @xmath11 \nonumber\end{aligned}\ ] ] where @xmath4 is the four - momentum transfer squared , @xmath12 is the bjorken scaling variable , @xmath13 is the inelasticity variable and @xmath14 . the contribution from @xmath1 dominates the cross - section . the contribution from @xmath3 is a qcd correction which is important only at large @xmath15 and that from @xmath16 is negligible for @xmath17 . to investigate sensitivity to @xmath3 at large @xmath15 or @xmath16 at large @xmath4. Please generate the next two sentences of the article

, the reduced cross - section @xmath18 is adopted . in the quark parton model ( or in the dis scheme of nlo qcd ) and for @xmath17 @xmath19 is the charge - weighted sum of the quark densities @xmath20 where @xmath21 $ ] is the _ singlet _ summed quark and anti - quark distributions .

Suppose that you have an abstract for a scientific paper: in the presence of a complex scalar field scalar - tensor theory allows for scalarized rotating hairy black holes . we exhibit the domain of existence for these scalarized black holes , which is bounded by scalarized rotating boson stars and ordinary hairy black holes . we discuss the global properties of these solutions . like their counterparts in general relativity , their angular momentum may exceed the kerr bound , and their ergosurfaces may consist of a sphere and a ring , i.e. , form an ergo - saturn . . And you have already written the first three sentences of the full article: one of the major discoveries in physics during the last two decades was the accelerated expansion of the universe . general relativity and the standard model of particle physics fail to explain this phenomenon . this situation calls for new alternative ideas able to give a satisfactory explanation of the cosmological observations .. Please generate the next two sentences of the article

one of the possibilities is to go beyond general relativity and to consider more general theories of gravity . among the most natural generalizations of the original einstein theory are the scalar - tensor theories @xcite . these theories are viable gravitational theories and can pass all known experimental and observational constraints .

Suppose that you have an abstract for a scientific paper: orbital angular momentum ( oam ) is a promising degree of freedom for fundamental studies in electromagnetics and quantum mechanics . the unlimited state space of oam shows a great potential to enhance channel capacities of classical and quantum communications . by exploring the pancharatnam - berry phase concept and engineering anisotropic scatterers in a metasurface with spatially varying orientations , a plane wave with zero oam can be converted to a vortex beam carrying nonzero oam . in this paper , we proposed two types of novel pec ( perfect electric conductor)-pmc ( perfect magnetic conductor ) anisotropic metasurfaces . one is composed of azimuthally continuous loops and the other is constructed by azimuthally discontinuous dipole scatterers . both types of metasurfaces are mounted on a mushroom - type high impedance surface . compared to previous metasurface designs for generating oam , the proposed ones achieve nearly perfect conversion efficiency . in view of the eliminated vertical component of electric field , the continuous metasurface shows very smooth phase pattern at the near - field region , which can not be achieved by convectional metasurfaces composed of discrete scatterers . on the other hand , the metasurface with discrete dipole scatterers shows a great flexibility to generate oam with arbitrary topological charges . our work is fundamentally and practically important to high - performance oam generation . . And you have already written the first three sentences of the full article: electromagnetic momentum density can be decomposed in terms of orbital momentum and spin momentum densities @xcite . they are respectively responsible for the generation of the orbital angular momentum ( oam ) and spin angular momentum ( sam ) of electromagnetic ( em ) waves . left and right circularly polarized em waves carry sam of @xmath0 that is intrinsic ( origin - independent ) physical quantity . fundamentally different from sam , oam is an extrinsic origin - dependent quantity , which can be carried by vortex beams with a helical wavefront @xcite . on the other hand , the unbounded eigenstates of oam could enhance capacities of radio , optical and quantum communications @xcite . additionally , oam has various potential applications involving super - resolution imaging @xcite , optical tweezers @xcite , etc .. Please generate the next two sentences of the article

there are several approaches to generate oam of em waves . one common approach is to introduce desired phase retardation by spiral phase plates @xcite , antenna arrays @xcite , holographic plates @xcite , etc .

Suppose that you have an abstract for a scientific paper: for a sample of 96,951 galaxies from the sloan digital sky survey data release 3 , we study the distribution of apparent axis ratios as a function of @xmath0-band absolute magnitude and surface brightness profile type . we use the parameter ` fracdev ` to quantify the profile type ( @xmath1 for a pure de vaucouleurs profile ; @xmath2 for a pure exponential profile ) . when the apparent axis ratio @xmath3 is estimated from the moments of the light distribution , the roundest galaxies are very bright ( @xmath4 ) de vaucouleurs galaxies and the flattest are modestly bright ( @xmath5 ) exponential galaxies . when the axis ratio @xmath6 is estimated from the axis ratio of the 25 mag / arcsec@xmath7 isophote , we find that de vaucouleurs galaxies , at this low surface brightness , are flatter than exponential galaxies of the same absolute magnitude . for a given surface brightness profile type , very bright galaxies are rounder , on average , than fainter galaxies . we deconvolve the distributions of apparent axis ratios to find the distribution of the intrinsic short - to - long axis ratio @xmath8 , making the assumption of constant triaxiality @xmath9 . for all profile types and luminosities , the distribution of axis ratios is inconsistent with a population of oblate spheroids , but is usually consistent with a population of prolate spheroids . bright galaxies with a de vaucouleurs profile ( @xmath10 , @xmath11 ) have a distribution of @xmath3 that is consistent with triaxiality in the range @xmath12 , with mean axis ratio @xmath13 . the fainter de vaucouleurs galaxies are best fit with prolate spheroids ( @xmath14 ) with mean axis ratio @xmath15 . . And you have already written the first three sentences of the full article: the galaxy classification scheme of @xcite has proved durably useful . as modified and extended by @xcite , it is still the standard method for classifying low - redshift galaxies with high surface brightness . the hubble classification scheme was originally based on the appearance of galaxies on photographic plates . elliptical galaxies have smooth elliptical isophotes ; spiral galaxies have spiral arms that wind outward from a central bulge or bar .. Please generate the next two sentences of the article

it was later discovered that for luminous galaxies , the surface brightness profile is strongly correlated with the hubble type . if the surface brightness @xmath16 is measured along the major axis of a galaxy s image , it is found that bright elliptical galaxies have surface brightness profiles that are well fit by a de vaucouleurs , or @xmath17 law , for which @xmath18 @xcite .

Suppose that you have an abstract for a scientific paper: the key results on lepton - pair production in ultra - relativistic nuclear collisions are shortly reviewed , starting at the roots of @xmath0 collisions in the seventies , and ending at the perspectives of the colliders rhic and lhc . the presence is dominated by the recent precision results from na60 at the cern sps , culminating in the first measurement of the in - medium @xmath1 spectral function and the transverse flow of the associated thermal radiation . the seeming cut - off of the flow above the @xmath1 may well be the first direct hint for thermal radiation of partonic origin in nuclear collisions . the major milestones in the theoretical developments are also covered . relativistic heavy - ion collisions , quark - gluon plasma , lepton pairs 25.75.-q , 12.38.mh , 13.85.qk . And you have already written the first three sentences of the full article: the interest in continuum lepton - pair production in high - energy collisions dates back to the seventies , triggered by the detection of the drell - yan process @xcite and the @xmath3 . the latter , in particular , sharpened the attention to anything which might still have escaped detection , and a flood of new experimental findings on lepton pairs appeared , both for low masses ( lmr , m@xmath41 gev ) and for intermediate masses ( imr , 1@xmath4m@xmath42.5 gev ) . the results were usually compared to expectations from an `` hadron - decay cocktail '' , containing all contributions known at that time .. Please generate the next two sentences of the article

an excess of single leptons and lepton pairs above the known sources was indeed found , coined `` anomalous '' pairs , and created great excitement . a review of the situation in the lmr region as of 1984 is contained in @xcite . unfortunately , the results did not survive critical reassessment in later years , and they were finally recognized by helios-1 @xcite and , with higher precision , by ceres @xcite as due to a severe underestimate of the contribution from @xmath5 dalitz decays .

Suppose that you have an abstract for a scientific paper: in a world in which many pressing global issues require large scale cooperation , understanding the group size effect on cooperative behavior is a topic of central importance . yet , the nature of this effect remains largely unknown , with lab experiments insisting that it is either positive or negative or null , and field experiments suggesting that it is instead curvilinear . here we shed light on this apparent contradiction by considering a novel class of public goods games inspired to the realistic scenario in which the natural output limits of the public good imply that the benefit of cooperation increases fast for early contributions and then decelerates . we report on a large lab experiment providing evidence that , in this case , group size has a curvilinear effect on cooperation , according to which intermediate - size groups cooperate more than smaller groups and more than larger groups . in doing so , our findings help fill the gap between lab experiments and field experiments and suggest concrete ways to promote large scale cooperation among people . . And you have already written the first three sentences of the full article: cooperation has played a fundamental role in the early evolution of our societies@xcite and continues playing a major role still nowadays . from the individual level , where we cooperate with our romantic partner , friends , and co - workers in order to handle our individual problems , up to the global level where countries cooperate with other countries in order to handle global problems , our entire life is based on cooperation . given its importance , it is not surprising that cooperation has inspired an enormous amount of research across all biological and social sciences , spanning from theoretical accounts @xcite to experimental studies @xcite and numerical simulations@xcite .. Please generate the next two sentences of the article

since the resolution of many pressing global issues , such as global climate change and depletion of natural resources , requires cooperation among many actors , one of the most relevant questions about cooperation regards the effect of the size of the group on cooperative behavior . indeed , since the influential work by olson @xcite , scholars have recognized that the size of a group can have an effect on cooperative decision - making .

Suppose that you have an abstract for a scientific paper: we demonstrate high speed manipulation of a few - electron double quantum dot . in the one - electron regime , the double dot forms a charge qubit . microwaves are used drive transitions between the ( 1,0 ) and ( 0,1 ) charge states of the double dot . a local quantum point contact charge detector measures the photon - induced change in occupancy of the charge states . charge detection is used to measure @xmath0@xmath116 ns and also provides a lower bound estimate for @xmath2 of 400 ps for the charge qubit . in the two - electron regime we use pulsed - gate techniques to measure the singlet - triplet relaxation time for nearly - degenerate spin states . these experiments demonstrate that the hyperfine interaction leads to fast spin relaxation at low magnetic fields . finally , we discuss how two - electron spin states can be used to form a logical spin qubit . , , , , , , , and , charge qubit , spin qubit , rabi oscillation , coherent manipulation 03.67.mn , 72.25.rb , 85.35.gv semiconducting quantum dots can be used to confine single electrons in an electrically controllable potential @xcite . coupled quantum dots , containing a single electron , create a tunable two - level system for the manipulation of single charges @xcite . by a similar approach , when two electrons are confined to a double dot the relaxation and dephasing of singlet and triplet spin states can be studied @xcite . recently , we have demonstrated coherent control of two - electron spin states by using high speed pulsed gate techniques @xcite . in this paper , we review recent experiments performed by our group on few - electron quantum dots that demonstrate quantum control of just one or two electrons @xcite . samples are fabricated from a gaas / al@xmath3ga@xmath4as heterostructure grown by molecular beam epitaxy ( fig . 1(a ) ) . electron beam lithography and liftoff techniques are used to fabricate ti / au gates , which deplete the two - dimensional electron gas with.... And you have already written the first three sentences of the full article: control of the double dot using dc gate voltages is demonstrated in fig . 1 ( b d ) . figure 1(b ) shows @xmath20/@xmath28 ( numerically differentiated ) as a function of @xmath12 and @xmath11 . when an electron enters or leaves the double dot , or moves from one dot to the other , the qpc conductance changes . gate voltage derivatives of @xmath18 and @xmath19 clearly show these changes and map out the double dot charge stability diagram @xcite .. Please generate the next two sentences of the article

the nearly horizontal lines are due to charge transitions in the left dot , while the nearly vertical lines correspond to charge transitions in the right dot . for very negative values of @xmath11 and @xmath12 ( see the lower left corner of the charge stability diagram ) charge transitions no longer occur , indicating that the double dot is completely empty , denoted ( 0,0 ) .

Suppose that you have an abstract for a scientific paper: we introduce the korringa - kohn - rostocker non - local coherent potential approximation ( kkr - nlcpa ) for describing the electronic structure of disordered systems . the kkr - nlcpa systematically provides a hierarchy of improvements upon the widely used kkr - cpa approach and includes non - local correlations in the disorder configurations by means of a self - consistently embedded cluster . the kkr - nlcpa method satisfies all of the requirements for a successful cluster generalization of the kkr - cpa ; it remains fully causal , becomes exact in the limit of large cluster sizes , reduces to the kkr - cpa for a single - site cluster , is straightforward to implement numerically , and enables the effects of short - range order upon the electronic structure to be investigated . in particular , it is suitable for combination with electronic density functional theory to give an ab - initio description of disordered systems . future applications to charge correlation and lattice displacement effects in alloys and spin fluctuations in magnets amongst others are very promising . we illustrate the method by application to a simple one - dimensional model . . And you have already written the first three sentences of the full article: over the past 30 years or so the coherent potential approximation @xcite ( cpa ) has proved to be a generally reliable method for dealing with disordered systems . @xcite however , being in essence a single - site mean - field theory , @xcite the cpa fails to take into account the effect of non - local potential correlations due to the disorder in the environment of each site and hence leaves much important physics out of consideration . consequently , considerable effort has been spent in trying to find a way of improving it systematically by a multi - site or cluster generalization .. Please generate the next two sentences of the article

surprisingly this has turned out to a very difficult problem @xcite and a viable solution has been proposed only recently . the new method has emerged from the dynamical cluster approximation @xcite ( dca ) which was directed originally at describing dynamical spin and charge fluctuations in simple hubbard models of strongly - correlated electron systems .

Suppose that you have an abstract for a scientific paper: kicked double - well system is investigated both analytically and numerically . phenomenological formula for ground quasienergy splitting is obtained using resonances overlap criterion in the framework of chaotic instanton approach . results of numerical calculations of quasienergy spectrum are in good agreement with the phenomenological formula . . And you have already written the first three sentences of the full article: semiclassical properties of systems with mixed classical dynamics is a reach rapidly developing field of research . one of interesting results obtained in this direction is a chaos assisted tunneling . it was shown that the structure of the classical phase space of hamiltonian systems can influence such purely quantum processes as the tunneling @xcite .. Please generate the next two sentences of the article

it was demonstrated in numerical simulations that existence of chaotic motion region in the classical phase space of the system can increase or decrease tunneling rate by several orders of magnitude @xcite . typically one considers tunneling between kam - tori embedded into the `` chaotic sea '' .

Suppose that you have an abstract for a scientific paper: device - independent quantum key distribution ( diqkd ) is a formalism that supersedes traditional quantum key distribution , as its security does not rely on any detailed modelling of the internal working of the devices . this strong form of security is possible only using devices producing correlations that violate a bell inequality . full security proofs of diqkd have been recently reported , but they tolerate zero or small amounts of noise and are restricted to protocols based on specific bell inequalities . here , we provide a security proof of diqkd that is both more efficient and noise resistant , and also more general as it applies to protocols based on arbitrary bell inequalities and can be adapted to cover supra - quantum eavesdroppers limited by the no - signalling principle only . it requires , however , the extra assumption that the adversary does not have a long - term quantum memory , a condition that is not a limitation at present since the best existing quantum memories have very short coherence times . . And you have already written the first three sentences of the full article: quantum key distribution is the art of distilling a secret key between two distant parties , alice and bob , who have access to an untrusted quantum channel @xcite . in this scenario , one typically assumes that the equipment in alice and bob s labs can be trusted , and moreover , that its behavior is accurately described by a given theoretical model . unfortunately , this often turns out to be a very strong assumption which is not justified in practice @xcite .. Please generate the next two sentences of the article

in particular , many loopholes can be exploited by an eavesdropper to get around the usual security proofs : for instance , the state preparation might be imperfect @xcite , or the eavesdropper might perform a blinding attack to take control of the detectors at a distance @xcite . one way around such problems consists in exhaustively listing all the potential mismatches between the theoretical model and the real implementation and taking care of each one of them individually . however , this approach is dubious as it is impossible to be sure that all loopholes have really been addressed .

Suppose that you have an abstract for a scientific paper: i give a brief review of final state interactions ( fsi ) in heavy meson decays , paying particular attention to @xmath0-meson physics . available theoretical methods for dealing with the effects of fsi are discussed . . And you have already written the first three sentences of the full article: strong interaction phases play an important role in the decays of heavy mesons . they produce visible effects in many nonleptonic decays and could be important for the proper interpretation of effects of underlying fundamental physics . for example , strong phases between isospin amplitudes , @xmath1 and @xmath2 , @xmath3 affect branching ratios of individual decays , as well as ratios of rates of isospin - related transitions . more importantly , they complicate interpretations of cp - violating phases from @xmath4 transitions observed in the so - called direct cp - violating asymmetries .. Please generate the next two sentences of the article

provided that b - decay amplitude depends on at least two amplitudes with different weak and strong phases ( for example , tree @xmath5 and penguin @xmath6 amplitudes ) , @xmath7 a cp - violating asymmetry can be formed , @xmath8 which clearly depends on both , cp - conserving @xmath9 and cp - violating phase @xmath10 differences . cp - conserving phase difference is associated with strong interactions . there are , of course , many more examples .

Suppose that you have an abstract for a scientific paper: in the framework of monitoring by ocean drifters ( mondo ) project , a set of lagrangian drifters were released in proximity of the brazil current , the western branch of the subtropical gyre in the south atlantic ocean . the experimental strategy of deploying part of the buoys in clusters offers the opportunity to examine relative dispersion on a wide range of scales . adopting a dynamical systems approach , we focus our attention on scale - dependent indicators , like the finite - scale lyapunov exponent ( fsle ) and the finite - scale ( mean square ) relative velocity ( fsrv ) between two drifters as function of their separation , and compare them with classic time - dependent statistical quantities like the mean square relative displacement between two drifters and the effective diffusivity as functions of the time lag from the release . we find that , dependently on the given observable , the quasigeostrophic turbulence scenario is overall compatible with our data analysis , with discrepancies from the expected behavior of 2d turbulent trajectories likely to be ascribed to the non stationary and non homogeneous characteristics of the flow , as well as to possible ageostrophic effects . submesoscale features of @xmath0 km are considered to play a role , to some extent , in determining the properties of relative dispersion as well as the shape of the energy spectrum . we present , also , numerical simulations of an ogcm of the south atlantic , and discuss the comparison between experimental and model data about mesoscale dispersion . . And you have already written the first three sentences of the full article: detailed investigation of geophysical flows involves experimental campaigns in which buoys , in the ocean , or balloons , in the atmosphere , are released in order to collect lagrangian data against which theories and models can be tested . questions concerning oil spill fate , fish larvae distribution or search and rescue operations are only a few examples that make the study of advection and diffusion properties not only a challenging scientific task , but also a matter of general interest . in the past years , an amount of lagrangian data about the south atlantic ocean ( sao ) was collected thanks to the first global atmospheric research program ( garp ) global experiment ( fgge ) drifters , released following the major shipping lines , the southern ocean studies ( sos ) drifters , deployed in the brazil - malvinas confluence ( bmc ) and the programa nacional de bias ( pnboia ) drifters [ brazilian contribution to the global oceans observing system ( goos ) ] , released in the southeastern brazilian bight ( sbb ) . these data allowed estimates of eddy kinetic energy ( eke ) , integral time scales and diffusivities ( piola et al .. Please generate the next two sentences of the article

1987 ; figueroa and olson 1989 ; schfer and krauss 1995 ) . despite the relatively uniform coverage , the boundary currents resulted poorly populated by buoys ; furthermore , all previous studies about drifters in the south atlantic have concerned one - particle statistics only . in this regard , in the framework of monitoring by ocean drifters ( mondo ) project , a recent lagrangian experiment , consisting in the release of a set of 39 world ocean circulation experiment ( woce ) surface velocity program ( svp ) drifters , was planned in relationship with an oil drilling operation in proximity of the coast of brazil , around ( @xmath1s , @xmath2w ) . part of the drifters were deployed in 5-element clusters , some of them with initial drifter separations smaller than 1 km .

Suppose that you have an abstract for a scientific paper: analysis on the daily variations of cosmic ray muons with @xmath0 based on the data of two directional muon telescopes at sea level and with a rigidity of response to cosmic proton spectrum above 0.4 gv is presented . the analysis covers two months of observations and in 60% of days , abrupt transitions between a low to a high muon intensity and vice - verse is observed , the period of high muon intensity is from @xmath1 up to @xmath2 ( local time ) and coincides with the period when the interplanetary magnetic field ( imf ) lines overtake the earth . this behavior strongly suggest that the high muon intensity is due to a contribution of solar protons ( ions ) on the muon intensity produced by the galactic cosmic rays , responsible for the low muon intensity . this implies that the solar particle spectrum extends to energies beyond 1 gev . we show that this picture can explain the solar daily variation origin , and it is a most accurate scenario than the assumption of corotating galactic cosmic ray with the imf lines , specially in the high rigidity region . obtained results are consistent with the data reported in others papers . some aspects on the sensitivity of our muon telescopes are also presented . . And you have already written the first three sentences of the full article: galactic cosmic rays ( gcr ) beyond the heliosphere region are considered to be temporally and spatially isotropic at least over large timescales . they enter into the heliosphere due to random motions and they are subjected to a number of transport effects such as diffusion , adiabatic cooling , convection and drift @xcite . the relative importance of these processes varies with particle properties , such as energy , timescales and of course the position in space .. Please generate the next two sentences of the article

the size and structure of the modulation volume is assumed to be approximately a sphere with a radius of @xmath3 au . on the other hand , the term `` solar energetic particles '' ( sep ) include all particles in the heliosphere accelerated by processes related to solar activity , such as the anomalous cosmic ray ( acr ) , particles accelerated in corotating interaction region ( cir ) , as well as particles accelerated in solar flares and coronal mass ejection ( cme ) . while , it is believed that particles , continuously expelled by the sun , such as the solar wind plasma , have energies up to several gevs in the tail of the solar energy spectrum and only during transient solar events ( i.e. solar flares ) their energies can reach dozens of gevs .

Suppose that you have an abstract for a scientific paper: we study topological d - branes of type b in @xmath0 landau - ginzburg models , focusing on the case where all vacua have a mass gap . in general , tree - level topological string theory in the presence of topological d - branes is described mathematically in terms of a triangulated category . for example , it has been argued that b - branes for an @xmath0 sigma - model with a calabi - yau target space are described by the derived category of coherent sheaves on this space . m. kontsevich previously proposed a candidate category for b - branes in @xmath0 landau - ginzburg models , and our computations confirm this proposal . we also give a heuristic physical derivation of the proposal . assuming its validity , we can completely describe the category of b - branes in an arbitrary massive landau - ginzburg model in terms of modules over a clifford algebra . assuming in addition homological mirror symmetry , our results enable one to compute the fukaya category for a large class of fano varieties . we also provide a ( somewhat trivial ) counter - example to the hypothesis that given a closed string background there is a unique set of d - branes consistent with it . . And you have already written the first three sentences of the full article: topological open strings and topological d - branes have recently been enjoying the attention of both physicists and mathematicians . the most obvious physical motivation for studying topological string theory is that it is a toy - model for `` physical '' string theory . thus a better understanding of topological d - branes could shed light on the general definition of a boundary condition for a two - dimensional conformal field theory ( 2d cft ) , something which is not known at present .. Please generate the next two sentences of the article

further , if a 2d topological field theory ( 2d tft ) is obtained by twisting a 2d supersymmetric field theory , then it is possible to regard topological d - branes as a special class of `` physical '' d - branes ( bps d - branes ) . in fact , much of recent progress in string theory has resulted from studying bps d - branes . from the mathematical viewpoint ,

Suppose that you have an abstract for a scientific paper: standard solar models predict a solar luminosity that gradually increased by about 30% over the past 4.5 billion years . under the faint sun , earth should have been frozen solid for most of its existence . yet , running water is observed to have been present since very early in earth s history . this enigma is known as the faint sun paradox . we show here that it can be partially resolved once we consider the cooling effect that cosmic rays are suspected to have on the global climate and that the younger sun must have had a stronger solar wind , such that it was more effective at stopping cosmic rays from reaching earth . the paradox can then be completely resolved with the further contribution of modest greenhouse gas warming . when we add the cosmic ray flux modulation by a variable star formation rate in the milky way , we recover the long term glacial activity on earth . as to the future , we find that the average global temperature will increase by typically @xmath0k in the coming 2 gyr . . And you have already written the first three sentences of the full article: according to standard solar models , the solar luminosity increased from about 70% of the present solar luminosity at 4.5 gyr before present ( bp ) to its present value . if earth were a black body , its temperature would have been @xmath1k lower , enough to have kept large parts of it frozen until about 1 - 2 gyr bp . besides however the past eon , and the eon between 2 and 3 gyr bp , it appears that glaciations were altogether absent from the global surface .. Please generate the next two sentences of the article

this is the crux of the faint sun paradox [ _ sagan & mullen _ , 1972 ; _ pollack _ , 1991 ; _ sagan & chyba _ , 1997 ] . a common solution to this apparent paradox is that larger amounts of the greenhouse gas ( ghg ) co@xmath2 compensated for the cooler sun [ _ kuhn & kasting _ , 1983 ; _ kasting _ , 1993 ] .

Suppose that you have an abstract for a scientific paper: we provide a quantitative determination of the crystallization onset for two electrons in a parabolic two - dimensional confinement . this system is shown to be well described by a roto - vibrational model , wigner crystallization occurring when the rotational motion gets decoupled from the vibrational one . the wigner molecule thus formed is characterized by its moment of inertia and by the corresponding sequence of rotational excited states . the role of a vertical magnetic field is also considered . additional support to the analysis is given by the hartree - fock phase diagram for the ground state and by the random - phase approximation for the moment of inertia and vibron excitations . . And you have already written the first three sentences of the full article: for a low enough electron density , wigner@xcite predicted that electrons should localize creating an ordered spatial structure , thenceforth named a wigner crystal , that breaks the complete translational symmetry of the homogeneous electron gas ( also see ref . ) . indeed , the formation of the wigner crystal was observed in two - dimensional ( 2d ) distributions of electrons on the surface of liquid helium.@xcite a phase transition , induced by the magnetic field , from an electron liquid to a crystalline structure has also been reported for a 2d electron plasma at a gaas / algaas heterojunction.@xcite the existence of different phases in quantum dots , where a few electrons are confined into a small space , has become a topical subject in mesoscopic physics ( see , for a recent review , ref . ) . in fact , the high controllability of quantum dots suggests that these systems could provide an attractive opportunity to achieve the appropriate conditions for localized states .. Please generate the next two sentences of the article

it is precisely to stress this controllability that the names _ artificial atoms _ and _ quantum dots _ have been coined . there is a general persuasion that the wigner crystallization in quantum dots , whose localized states are referred to as wigner molecules , should occur at significantly larger densities than in the 2d bulk .

Suppose that you have an abstract for a scientific paper: we present results from neutral hydrogen ( hi ) observations of the tip of the magellanic stream ( ms ) , obtained with the arecibo telescope as a part of the on - going survey by the consortium for galactic studies with the arecibo l - band feed array . we find four large - scale , coherent hi streams , extending continously over a length of 20 degrees , each stream possessing different morphology and velocity gradients . the newly discovered streams provide strong support for the tidal model of the ms formation by @xcite , which suggested a spatial and kinematic bifurcation of the ms . the observed morphology and kinematics suggest that three of these streams could be interpreted as a 3-way splitting of the main ms filament , while the fourth stream appears much younger and may have originated from the magellanic bridge . we find an extensive population of hi clouds at the tip of the ms . two thirds of clouds have an angular size in the range 3.5@xmath010@xmath0 . we interpret this as being due to thermal instability , which would affect a warm tail of gas trailing through the galactic halo over a characteristic timescale of a few myrs to a few hundred myrs . we show that thermal fragments can survive in the hot halo for a long time , especially if surrounded by a @xmath1 k halo gas . if the observed clumpy structure is mainly due to thermal instability , then the tip of the ms is at a distance of @xmath2 kpc . a significant fraction of hi clouds at the tip of the ms show multi - phase velocity profiles , indicating the co - existence of cooler and warmer gas . . And you have already written the first three sentences of the full article: the magellanic stream ( ms ) , a 10 wide tail of neutral hydrogen ( hi ) emanating from the magellanic clouds and trailing for almost 100 on the sky ( dec @xmath3 to @xmath4 ) @xcite , is the only clear example of a gaseous halo stream in the milky way s close proximity . while it is well accepted that the ms is the result of interactions between the milky way ( mw ) and the magellanic clouds , the relative importance of tidal stripping and various kinds of gasdynamical interactions is still very much under debate . most recently several new attempts were made to model the observed hi column density and velocity distribution as being due to purely tidal stripping @xcite , or gravitational @xmath5 hydrodynamical interactions @xcite . these models focus on reproducing general features in the magellanic system , and gradients in hi column density and velocity along the ms . to add more excitement to this topic , recent estimates of the proper motion of the small magellanic cloud ( smc ) by @xcite and the most recent calculations of the magellanic cloud s orbits by @xcite suggest , contrary to all previous studies , that the clouds are only on their first passage around the mw .. Please generate the next two sentences of the article

the new orbits imply that neither tidal nor ram pressure stripping would have had enough time to produce the ms , calling for alternative formation mechanisms . the distance to the ms , especially to its tip , or the region the farthest away from the magellanic clouds , is another contentious question and varies greatly between models . under the ram pressure hypothesis

Suppose that you have an abstract for a scientific paper: mass models for a sample of 18 late - type dwarf and low surface brightness galaxies show that in almost all cases the contribution of the stellar disks to the rotation curves can be scaled to explain most of the observed rotation curves out to two or three disk scale lengths . the concept of a maximum disk , therefore , appears to work as well for these late - type dwarf galaxies as it does for spiral galaxies . some of the mass - to - light ratios required in our maximum disk fits are high , however , up to about 15 in the @xmath0-band , with the highest values occurring in galaxies with the lowest surface brightnesses . equally well - fitting mass models can be obtained with much lower mass - to - light ratios . regardless of the actual contribution of the stellar disk , the fact that the maximum disk can explain the inner parts of the observed rotation curves highlights the similarity in shapes of the rotation curve of the stellar disk and the observed rotation curve . this similarity implies that the distribution of the total mass density is closely coupled to that of the luminous mass density in the inner parts of late - type dwarf galaxies . . And you have already written the first three sentences of the full article: late - type dwarf galaxies are commonly thought to have slowly rising rotation curves and to be dominated by dark matter at all radii ( e.g. , carignan & beaulieu 1989 ; persic et al . 1996 ; ct et al . however , in a recent study of a large sample of late - type dwarf galaxies for which the rotation curves were derived in a uniform way , taking the effects of beam smearing into account , swaters et al .. Please generate the next two sentences of the article

( 2009 ) found that the rotation curves of late - type dwarf galaxies have shapes similar to those of late - type spiral galaxies . for the dwarf galaxies in their sample , the rotation curves , when expressed in units of disk scale lengths , rise steeply in the inner parts and start to flatten at two disk scale lengths , as is usually seen in spiral galaxies ( e.g. , broeils 1992a ; verheijen & sancisi 2001 ) .

Suppose that you have an abstract for a scientific paper: the @xmath0@xmath1 mixing angle is calculated in framework of the qcd sum rules . we find that our prediction for the mixing angle is @xmath2 which is in good agreement with the quark model prediction , and more than two times larger than the recent lattice qcd calculations . # 1#2#3 @xmath3 # 1#2#3 @xmath3 0^*0 5_5 o _ ^0 _ pacs numbers : 11.55.hx , 11.30.hv , 12.38.t , 14.20.jn . And you have already written the first three sentences of the full article: flavor symmetry plays essential role in classification of the hadrons . the light hadronic states are successfully described by using su(3 ) flavor symmetry . in the case this symmetry is exact , hadrons belonging to the same representation of su(3 ) flavor group could be degenerate . experimentally it is known that the hadrons belonging to the same representation have different masses , which leads to su(3 ) flavor symmetry breaking . at quark level. Please generate the next two sentences of the article

, this symmetry is broken due to the mass difference of the light u , d and s quarks . the breaking of the su(3 ) flavor symmetry might lead to mixing of hadrons .

Suppose that you have an abstract for a scientific paper: starting from a small number of well - motivated axioms , we derive a unique definition of sums with a noninteger number of addends . these `` fractional sums '' have properties that generalize well - known classical sum identities in a natural way . we illustrate how fractional sums can be used to derive infinite sum and special functions identities ; the corresponding proofs turn out to be particularly simple and intuitive . `` god made the integers ; all else is the work of man . '' leopold kronecker . And you have already written the first three sentences of the full article: mathematics is the art of abstraction and generalization . historically , `` numbers '' were first natural numbers ; then rational , negative , real , and complex numbers were introduced ( in some order ) . similarly , the concept of taking derivatives has been generalized from first , second , and higher order derivatives to `` fractional calculus '' of noninteger orders ( see for instance @xcite ) , and there is also some work on fractional iteration .. Please generate the next two sentences of the article

however , when we add some number of terms , this number ( of terms ) is still generally considered a natural number : we can add two , seven , or possibly zero numbers , but what is the sum of the first @xmath0 natural numbers , or the first @xmath1 terms of the harmonic series ? in this note , we show that there is a very natural way of extending summations to the case when the `` number of terms '' is real or even complex . one would think that this method should have been discovered at least two hundred years ago and that is what we initially suspected as well . to our surprise , this method does not seem to have been investigated in the literature , or to be known by the experts , apart from sporadic remarks even in euler s work @xcite ( see equation ( [ eq : euler ] ) below ) .

Suppose that you have an abstract for a scientific paper: deep surveys in many wavebands have shown that the rate at which stars were forming was at least a factor of 10 higher at redshifts @xmath0 than today . heavy elements ( ` metals ' ) are produced by stars , and the star formation history deduced by these surveys implies that a significant fraction of all metals in the universe today should already exist at @xmath1 . however , only 10% of the total metals expected to exist at this redshift have so far been accounted for ( in damped lyman alpha absorbers and the lyman forest ) . in this paper , we use the results of submillimetre surveys of the local and high redshift universe to show that there was much more dust in galaxies in the past . we find that a large proportion of the missing metals are traced by this dust , bringing the metals implied from the star formation history and observations into agreement . we also show that the observed distribution of dust masses at high redshift can be reproduced remarkably well by a simple model for the evolution of dust in spheroids , suggesting that the descendants of the dusty galaxies found in deep submm surveys are the relatively dust - free spiral bulges and ellipticals in the universe today . galaxies : evolution galaxies : ism galaxies : luminosity function , mass function submillimetre ( ism):dust , extinction . And you have already written the first three sentences of the full article: the star formation history ( sfh ) of the universe deduced from optical / uv surveys ( lilly et al . 1996 ; madau et al . 1996 , 1998 ) has recently been revised to account for dust extinction ( steidel et al . 1999 ) , largely motivated by the detection of a population of dusty star - forming objects in deep submm surveys with scuba ( hughes et al . 1998 ; eales et al . 1999 ; smail , ivison & blain 1997 ; scott et al . 2002 ) .. Please generate the next two sentences of the article

the current best estimate of the sfh is that the global star - formation rate in the universe was fairly constant over the redshift interval @xmath2 , falling by a factor @xmath3 to the present epoch , see fig . [ sfrdf ] .

Suppose that you have an abstract for a scientific paper: we elucidate the finite temperature entanglement properties of @xmath0 qubits heisenberg @xmath1 and @xmath2 models under the presence of a polarized magnetic field in @xmath3 plane by means of concurrence concept . we perform a systematic analysis for a wide range of the system parameters . our results suggest that the global phase regions which separate the entangled and non - entangled regions sensitively depend upon the spin - spin interaction term of the @xmath4 component of two neighboring spins @xmath5 , temperature as well as polarized magnetic field components . thereby , we think that polarized magnetic field can be used a control parameter to determine the amount of thermal entanglement between pair of qubits for different temperatures and spin - spin interaction terms . moreover , it has been found that the nearest - neighbor pair of qubits does not point out a re - entrant type entanglement character when one only deals with the nearest - neighbor pair of qubits . however , as one considers next - nearest neighbor pair of qubits , it is possible to see the evidences of re - entrant type entanglement behaviors . thermal entanglement , quantum correlations , @xmath6 qubit heisenberg @xmath1 and @xmath2 models , polarized magnetic field . . And you have already written the first three sentences of the full article: when the nonlocal quantum correlations become important in a many - level system , one may not extract the complete information about individual sub - levels although the total information about the whole system is known . in such a case , sub - levels become strongly correlated with each other , and this fact may allow the information between two distant points ( such as two qubits separated by large distances ) to be communicated instantly . this phenomenon is called action at a distance , and such a pair of sub - levels is called entangled . formerly , einstein and his co - authors @xcite , as well as schrdinger @xcite argued that this `` spooky action at a distance '' is a direct consequence of incomplete nature of quantum mechanics .. Please generate the next two sentences of the article

however , after three decades , bell @xcite showed that einstein s realist idea based on the locality is wrong and it pioneered consecutive experimental realizations which proved that the predictions of quantum mechanics are true regarding the entanglement phenomenon as a nonlocal property of nature . during the last two decades , a great many experimental efforts have been devoted to entanglement phenomenon in a wide variety of physical systems including entanglement of many photons , mesoscopic systems , and so on @xcite .

Suppose that you have an abstract for a scientific paper: in this work we study the @xmath0 reaction . the leading order electromagnetic contributions to this process involve the @xmath1 vertex function with a highly virtual photon . we calculate this function at low energies using @xmath2 supplemented with the anomalous term for the @xmath3 interactions . tree level contributions involve the kaon form factors and the @xmath4 transition form factors . we improve this result , valid for low photon virtualities , replacing the lowest order terms in the kaon form factors and @xmath4 transition form factors by the form factors as obtained in @xmath5 in the former case and the ones extracted from recent data on @xmath6 in the latter case . we calculate rescattering effects which involve meson - meson amplitudes . the corresponding result is improved using the unitarized meson - meson amplitudes containing the scalar poles instead of the lowest order terms . using the babar value for @xmath7 , we calculate the contribution from intermediate @xmath8 . a good description of data is obtained in the case of destructive interference between this contribution and the previous ones , but more accurate data on the isovector @xmath4 transition form factor is required in order to exclude contributions from an intermediate isovector resonance to @xmath0 around @xmath9 . . And you have already written the first three sentences of the full article: recently , using the radiative return method @xcite , a new state , the @xmath8 ( also named @xmath10 in the literature ) , was observed in @xmath11 with the dipion invariant mass close to the @xmath12 region , explicitly , for @xmath13 mev @xcite . later on this state was also detected at bes in the @xmath14 reaction @xcite and belle in @xmath15 @xcite . in an update of the analysis of ref . @xcite , results on the channel @xmath16 were presented in the form of number of events as a function of the dikaon invariant mass @xcite .. Please generate the next two sentences of the article

indeed , in this work , the cross section for @xmath17 was measured as a function of the center of mass energy up to @xmath18 and it is shown there that this reaction is dominated by events where one kaon pair comes from the decay of a @xmath19 . selecting events with a kaon pair within @xmath20 of the @xmath19 mass , an enhancement in the invariant mass of the other kaon pair close to threshold is observed and suggested to be due to the @xmath12 tail , but the low statistics and uncertainties in the @xmath21 line shape prevent the authors to present a cross section for @xmath22 using the @xmath23 final state . inspired in the physics behind the radiative @xmath24 decay @xcite , a detailed theoretical study of @xmath25 for pions in @xmath26-wave was performed in @xcite .

Suppose that you have an abstract for a scientific paper: we derive a closed - form solution for the price of an average price as well as an average strike geometric asian option , by making use of the path integral formulation . our results are compared to a numerical monte carlo simulation . we also develop a pricing formula for an asian option with a barrier on a control process , combining the method of images with a partitioning of the set of paths according to the average along the path . this formula is exact when the correlation is zero , and is approximate when the correlation increases . . And you have already written the first three sentences of the full article: since the beginning of financial science , stock prices , option prices and other quantities have been described by stochastic and partial differential equations . since the 1980s however , the path integral approach , created in the context of quantum mechanics by richard feynman @xcite , has been introduced to the field of finance @xcite . earlier , norbert wiener @xcite , in his studies on brownian motion and the langevin equation , used a type of functional integral that turns out to be a special case of the feynman path integral ( see also mark kac @xcite , and for a general overview see kleinert @xcite and schulman @xcite ) . the power of path - integration for finance ( @xcite,@xcite ) lies in its ability to naturally account for payoffs that are path - dependent .. Please generate the next two sentences of the article

this makes path integration the method of choice to treat one of the most challenging types of derivatives , the path - dependent options . feynman and kleinert @xcite showed how quantum - mechanical partition functions can be approximated by an effective classical partition function , a technique which has been successfully applied to the pricing of path - dependent options ( see ref . @xcite and references therein , and refs .

Suppose that you have an abstract for a scientific paper: we show that the electroweak symmetry can be broken in a natural and phenomenologically acceptable way by a neutrino condensate . therefore , we assume as particle content only the chiral fermions and gauge bosons of the standard model and in addition right - handed neutrinos . a fundamental higgs field is absent . we assume instead that new interactions exist that can effectively be described as four - fermion interactions and that can become critical in the neutrino sector . we discuss in detail the coupled dirac - majorana gap equations which lead to a neutrino condensate , electroweak symmetry breaking and via the dynamical see - saw mechanism to small neutrino masses . we show that the effective lagrangian is that of the standard model with massive neutrinos and with a composite higgs particle . the mass predictions are consistent with data . tum - hep-491/02 + desy 02 - 208 * dynamical electroweak symmetry breaking + by a neutrino condensate * + stefan antusch , jrn kersten , manfred lindner + _ physik - department t30 , technische universitt mnchen + james - franck - strae , 85748 garching , germany _ + michael ratz + _ deutsches elektronensynchrotron desy + 22603 hamburg , germany _ . And you have already written the first three sentences of the full article: the generalization of renormalizable relativistic gauge theories to the standard model ( sm ) was very successful and has been confirmed experimentally in an impressive way , including detailed tests of radiative corrections . , @xmath0 and @xmath1 in the neutrino sector may be the first signs of physics beyond the sm @xcite . ] however , it is important to keep in mind that the mechanism of electroweak ( ew ) symmetry breaking is still mostly untested . the postulated higgs particle has so far not been observed and there is only indirect evidence from quantum corrections that a sm higgs boson should be lighter than about @xmath2 @xcite .. Please generate the next two sentences of the article

the higgs sector has furthermore well - known theoretical problems , especially the gauge hierarchy problem , which strongly suggest that new physics exists which is connected to the mechanism of ew symmetry breaking . whatever the correct symmetry breaking mechanism is , it must satisfy by now a number of stringent direct and indirect constraints . given the success of the sm it is , however , immediately clear how an alternative symmetry breaking scenario can be consistent with data . in the limit

Suppose that you have an abstract for a scientific paper: using adaptive mesh - refinement cosmological hydrodynamic simulations with a physically motivated supernova feedback prescription we show that the standard cold dark matter model can account for extant observed properties of damped lyman alpha systems ( dlas ) . we then examine the properties of dla host galaxies . we find : ( 1 ) while dla hosts roughly trace the overall population of galaxies at all redshifts , they are always gas rich and have tendencies of being slightly smaller and bluer . ( 2 ) the history of dla evolution is cosmological in nature and reflects primarily the evolution of the underlying cosmic density , galaxy size and galaxy interactions . with higher density and more interactions at high redshift dlas are larger in both absolute terms and in relative terms with respect to virial radii of halos . ( 3 ) the variety of dlas at high redshift is richer with a large contribution coming from galactic filaments , created through close galaxy interactions . the portion of gaseous disks of galaxies where most stars reside makes relatively small contribution to dla incidence at @xmath0 . ( 4 ) the vast majority of dlas arise in halos of mass @xmath1 at @xmath2 , as these galaxies dominate the overall population of galaxies then . at @xmath0 , 20 - 30% of dla hosts are lyman break galaxies ( lbgs ) , 10 - 20% are due to galaxies more massive than lbgs and 50 - 70% are from smaller galaxies . ( 5 ) galactic winds play an indispensable role in shaping the kinematic properties of dlas . specifically , the high velocity width dlas are a mixture of those arising in high mass , high velocity dispersion halos and those arising in smaller mass systems where cold gas clouds are entrained to high velocities by galactic winds . ( 6 ) in agreement with observations , we see a weak but noticeable evolution in dla metallicity . the metallicity distribution centers at @xmath3=-1.5 $ ] to @xmath4 and spans more than three decades at @xmath0 , with the peak moving to @xmath3=-0.75 $ ] at.... And you have already written the first three sentences of the full article: damped @xmath9 systems ( dlas ) are fundamentally important , because they contain most of the neutral gas in the universe at all times since cosmological reionization ( e.g. , * ? ? ? * ; * ? ? ? * ; * ? ? ?. Please generate the next two sentences of the article

molecular clouds , within which star formation takes place , likely condense out of cold dense neutral atomic gas contained in dlas , evidenced by the fact that the neutral hydrogen ( surface ) density in dlas and molecular hydrogen ( surface ) density in molecular clouds form a continuous sequence ( e.g. , * ? ? ? * ; * ? ? ?

Suppose that you have an abstract for a scientific paper: the effect of the geomagnetic lorentz force on the muon component of extensive air shower ( eas ) has been studied in a monte carlo generated simulated data sample . this geomagnetic field affects the paths of muons in an eas , causing a local contrast or polar asymmetry in the abundance of positive and negative muons about the shower axis . the asymmetry can be approximately expressed as a function of transverse separation between the positive and negative muons barycentric positions in the eas through opposite quadrants across the shower core in the shower front plane . in the present study , it is found that the transverse muon barycenter separation and its maximum value obtained from the polar variation of the parameter are higher for iron primaries than protons for highly inclined showers . hence , in principle , these parameters can be exploited to the measurement of primary cosmic - ray chemical composition . possibility of practical realization of the proposed method in a real experiment is briefly discussed . . And you have already written the first three sentences of the full article: recent progress in astroparticle physics has improved our level of understanding of the outstanding unsolved problems concerning the origin , acceleration , and composition of primary cosmic rays ( pcrs ) during over past @xmath0 years since its discovery [ 1 ] at ultra - high energy ( uhe ) range with the continuous progress in experimental techniques and methods of measurements . nowadays we have relatively more sensitive eas experiments [ 2 - 5 ] consisting of a variety of modern detectors to observe the secondary components in an eas that contribute important results . on the other hand , to arrive at any specific conclusions about cosmic - rays ( crs ) from their indirect investigation it is very important to know how they interact with the atmosphere and how the eas develops . this knowledge is obtained by monte carlo ( mc ) simulations which are tested against data .. Please generate the next two sentences of the article

hence air shower simulations are a crucial part of the design of air shower experiments and analysis of their data . but a mc technique relies heavily on high energy hadronic models which suffer to some degree of uncertainties from one model to another and increasing primary energy . therefore , we are challenged to develop more accurate hadronic interaction models in place to predict robust results .

Suppose that you have an abstract for a scientific paper: in an effort to obtain further observational evidences for secular evolution processes in galaxies , as well as observational constraints to current theoretical models of secular evolution , we have used bvri and ks images of a sample of 18 barred galaxies to measure the lengths and colours of bars , create colour maps and estimate global colour gradients . in addition , applying a method we developed in a previous article , we could distinguish for 7 galaxies in our sample those whose bars have been recently formed from the ones with already evolved bars . we estimated an average difference in the optical colours between young and evolved bars that may be translated to an age difference of the order of 10 gyr , meaning that bars may be long standing structures . moreover , our results show that , on average , evolved bars are longer than young bars . this seems to indicate that , during its evolution , a bar grows longer by capturing stars from the disk , in agreement with recent numerical and analytical results . . And you have already written the first three sentences of the full article: the b - v colour difference between young and evolved bars is 0.4 mag , which can be translated to an age difference of 10 gyr . this means that bars can be robust structures , in agreement with recent @xmath0-body simulations and observations of barred galaxies at higher redshifts . the young bars in our sample have an average length of 5.4@xmath11.6 kpc , while the evolved bars have an average length of 7.5@xmath11.2 kpc , consistent with recent theoretical expectations that bars grow longer while aging .. Please generate the next two sentences of the article

young bars are preferentially found in late - type spirals , indicating that bar recurrence may be more frequent in gas - rich , disk - dominated galaxies . we also found that agn are preferentially hosted by galaxies with young bars , suggesting that the fueling of agn by bars happens in short timescales and that a clearer bar - agn connection would be found in a sample of galaxies with young bars .

Suppose that you have an abstract for a scientific paper: we present an analysis of the two - point angular correlation function of the elais s1 survey . the survey covers 4 deg@xmath0 and contains 462 sources detected at 15@xmath1 m to a 5@xmath2 flux limit of 0.45 mjy . using the 329 extragalactic sources not repeated in different observations , we detect a significant clustering signal ; the resulting angular correlation function can be fitted by a exponential law @xmath3 with @xmath4 and @xmath5 . assuming a redshift distribution of the objects , we invert limber s equation and deduce a spatial correlation length @xmath6mpc . this is smaller than that obtained from optical surveys but it is in agreement with results from iras . this extends to higher redshift the observational evidence that infrared selected surveys show smaller correlation lengths ( i.e. reduced clustering amplitudes ) than optical surveys . [ firstpage ] galaxies : clusters : general galaxies : evolution infrared : galaxies cosmology : observations large - scale structure of universe . And you have already written the first three sentences of the full article: theories of structure formation were strongly constrained by the statistical measurements of clustering in some of the early galaxy redshift surveys . surveys of infrared galaxies , in particular , were able to rule out the then standard cold dark matter model @xcite . present day redshift surveys such as the 2dfgrs @xcite , sdss @xcite and , in the far - infrared , the point source catalog redshift survey , psc - z @xcite are now able to provide definitive measurements of the galaxy clustering in the local universe . despite this success , we have always known that galaxies are biased tracers of the matter distribution and yet we have a poor observational or theoretical understanding of this bias , although it is assumed to be related to the process of galaxy formation and evolution . to understand bias and , by inference , galaxy formation. Please generate the next two sentences of the article

, we need to better understand the clustering of different galaxy types and the evolution of this clustering with redshift . in this paper we attempt to provide an estimate of the clustering of infrared galaxies a factor of ten deeper ( in redshift ) than those seen in the iras surveys . to do this we provide the first estimate of clustering from any of the extragalactic iso surveys .

Suppose that you have an abstract for a scientific paper: the famous fisher - kpp reaction diffusion model combines linear diffusion with the typical fisher - kpp reaction term , and appears in a number of relevant applications . it is remarkable as a mathematical model since , in the case of linear diffusion , it possesses a family of travelling waves that describe the asymptotic behaviour of a wide class solutions @xmath0 of the problem posed in the real line . the existence of propagation wave with finite speed has been confirmed in the cases of `` slow '' and `` pseudo - linear '' doubly nonlinear diffusion too , see @xcite . we investigate here the corresponding theory with `` fast '' doubly nonlinear diffusion and we find that general solutions show a non - tw asymptotic behaviour , and exponential propagation in space for large times . finally , we prove precise bounds for the level sets of general solutions , even when we work in with spacial dimension @xmath1 . in particular , we show that location of the level sets is approximately linear for large times , when we take spatial logarithmic scale , finding a strong departure from the linear case , in which appears the famous bramson logarithmic correction . . And you have already written the first three sentences of the full article: in this paper we study the doubly nonlinear ( dnl ) reaction - diffusion problem posed in the whole euclidean space @xmath2 we want to describe the asymptotic behaviour of the solution @xmath3 for large times and for a specific range of the parameters @xmath4 and @xmath5 . we recall that the @xmath6-laplacian is a nonlinear operator defined for all @xmath7 by the formula @xmath8 and we consider the more general diffusion term @xmath9 called `` doubly nonlinear''operator . here , @xmath10 is the spatial gradient while @xmath11 is the spatial divergence .. Please generate the next two sentences of the article

the doubly nonlinear operator ( which can be though as the composition of the @xmath12-th power and the @xmath6-laplacian ) is much used in the elliptic and parabolic literature ( see @xcite and their references ) and allows to recover the porous medium operator choosing @xmath13 or the @xmath6-laplacian operator choosing @xmath14 . of course , choosing @xmath15 and @xmath13 we obtain the classical laplacian . before proceeding ,

Suppose that you have an abstract for a scientific paper: we present the first detections by the nasa k2 mission of oscillations in solar - type stars , using short - cadence data collected during k2 campaign1 ( c1 ) . we understand the asteroseismic detection thresholds for c1-like levels of photometric performance , and we can detect oscillations in subgiants having dominant oscillation frequencies around @xmath0 . changes to the operation of the fine - guidance sensors are expected to give significant improvements in the high - frequency performance from c3 onwards . a reduction in the excess high - frequency noise by a factor of two - and - a - half in amplitude would bring main - sequence stars with dominant oscillation frequencies as high as @xmath1 into play as potential asteroseismic targets for k2 . . And you have already written the first three sentences of the full article: asteroseismology of solar - type stars has been one of the major successes of the nasa _ kepler _ mission ( gilliland et al . the nominal mission provided data of exquisite quality for unprecedented numbers of low - mass main - sequence stars and cool subgiants . asteroseismic detections were made in more than 600 field stars ( chaplin et al . 2011a ; 2014 ) , including a sample of _ kepler _ planet hosts ( huber et al .. Please generate the next two sentences of the article

these data have enabled a range of detailed asteroseismic studies ( see chaplin & miglio 2013 and references therein ) , many of which are ongoing . the nominal mission ended in 2013 may with the loss of a second of the spacecraft s four onboard reaction wheels . this meant the spacecraft could no longer maintain three - axis stabilized pointing .

Suppose that you have an abstract for a scientific paper: simulations estimating the brightness temperature ( @xmath0 ) of the redshifted 21-cm from the epoch of reionization ( eor ) often assume that the spin temperature ( @xmath1 ) is decoupled from the background cmb temperature and is much larger than it , i.e. , @xmath2 . although a valid assumption towards the latter stages of the reionization process , it does not necessarily hold at the earlier epochs . violation of this assumption will lead to fluctuations in @xmath3 that are neither driven by density fluctuations nor by @xmath4 regions . therefore , it is vital to calculate the spin temperature self - consistently by treating the ly@xmath5 and collisional coupling of @xmath1 to the kinetic temperature , @xmath6 . in this paper we develop an extension to the bears algorithm , originally developed to model reionization history , to include these coupling effects . here we simulate the effect in ionization and heating for three models in which the reionization is driven by stars , miniqsos or a mixture of both . we also perform a number of statistical tests to quantify the imprint of the self - consistent inclusion of the spin temperature decoupling from the cmb . we find that the evolution of the spin temperature has an impact on the measured signal specially at redshifts higher than 10 and such evolution should be taken into account when one attempts to interpret the observational data . [ firstpage ] physical data processes : radiative transfer cosmology : theory observation diffuse radiation radio lines : general . . And you have already written the first three sentences of the full article: physical processes that occur during reionization are numerous and complex . nevertheless , ionization of neutral gas ( hydrogen & helium ) and heating of the inter - galactic medium ( igm ) can be considered the two primary influences of radiating objects during reionization . currently , the most promising `` direct '' probe of reionization is the redshifted 21-cm radiation emanating from neutral hydrogen during the epoch of reionization ( eor ) , which are to be measured using upcoming telescopes like lofar , mwa , paper and 21cma . the intensity of the observed 21-cm radiation depends on the ratio between the number density of electrons in the hyperfine states in the ground state of a neutral hydrogen atom .. Please generate the next two sentences of the article

this ratio is normally expressed in terms of the so - called 21-cm spin temperature , @xmath1 . at the onset of the formation of the first reionizing objects the spin temperature is equal to the cmb temperature since at these redshifts the ratio between excited and ground hyperfine state electrons is completely determined by the cmb . however , as the number of ionizing sources increases , @xmath1 starts departing from @xmath7 ; slowly at the beginning , then rapidly approaching values larger than @xmath7 .

Suppose that you have an abstract for a scientific paper: black hole spin will have a large impact on searches for gravitational waves with advanced detectors . while only a few stellar mass black hole spins have been measured using x - ray techniques , gravitational wave detectors have the capacity to greatly increase the statistics of black hole spin measurements . we show what we might learn from these measurements and how the black hole spin values are influenced by their formation channels . . And you have already written the first three sentences of the full article: gravitational wave observations will be sensitive to the spins of black holes @xcite . simulated search pipelines indicate that accounting for black hole spin can substantially improve the sensitivity of gravitational wave searches for binaries containing one @xcite or two @xcite black holes . however , this improvement comes at a cost of increased computational resources and is only realised if the spins of black holes are indeed significant .. Please generate the next two sentences of the article

it is therefore necessary to balance the increased cost with the expectation that black holes will indeed have large spins . here we discuss that evidence .

Suppose that you have an abstract for a scientific paper: we present a general , systematic , and efficient method for decomposing any given exponential operator of bosonic mode operators , describing an arbitrary multi - mode hamiltonian evolution , into a set of universal unitary gates . although our approach is mainly oriented towards continuous - variable quantum computation , it may be used more generally whenever quantum states are to be transformed deterministically , e.g. in quantum control , discrete - variable quantum computation , or hamiltonian simulation . we illustrate our scheme by presenting decompositions for various nonlinear hamiltonians including quartic kerr interactions . finally , we conclude with two potential experiments utilizing offline - prepared optical cubic states and homodyne detections , in which quantum information is processed optically or in an atomic memory using quadratic light - atom interactions . _ introduction_ since the proposal of quantum computation as a generalization of computer science , an important theoretical challenge has been how to decompose an arbitrary gate into a universal set . the corresponding theory of discrete - variable decompositions is very extensive and mostly employs matrix representations of logic gates utilizing matrix decomposition techniques @xcite . in contrast to discrete - variable theory , there is not an established method to decompose an arbitrary operator in the continuous - variable ( cv ) regime except the proof - of - principle results on universal gate sets in refs . @xcite . in particular , ref . @xcite makes use of an exponential operator approximation and proves that by employing certain elementary gate sets ( discussed below ) one can derive any operator up to a certain error . however , none of these works intend to present a constructive and efficient decomposition recipe . the problem of decomposition is intrinsically related to the concept of universality . universality means to have a set of operators that allows you to simulate any operator on a.... And you have already written the first three sentences of the full article: @xmath55&=x^mp^n - p^nx^m\\ & = x^mp^n - p^{n-1}(x^mp-\frac{im}{2}x^{m-1})\\ & = x^mp^n+\frac{im}{2}p^{n-1}x^{m-1}-p^{n-2}px^mp\\ & = x^mp^n+\frac{im}{2}p^{n-1}x^{m-1}-p^{n-2}x^mp^2+\frac{im}{2}p^{n-2}x^{m-1}p\\ & = x^mp^n+\frac{im}{2}p^{n-1}x^{m-1}+\frac{im}{2}p^{n-2}x^{m-1}p - p^{n-2}x^mp^2\\ \vdots\\ & = \frac{im}{2}\sum_{k=0}^{n-1 } p^kx^{m-1}p^{n - k-1}\end{aligned}\ ] ] @xmath55&=\frac{im}{4}\sum_{k=0}^{n-1 } p^kx^{m-1}p^{n - k-1}+p^{n - k-1}x^{m-1}p^k\\ & = \frac{im}{4}\sum_{k=0}^{n-1 } \left ( ( x^{m-1}p^k-[x^{m-1},p^k])p^{n - k-1 } + p^{n - k-1}([x^{m-1},p^k]+p^kx^{m-1 } ) \right)\\ & = \frac{im}{4}\sum_{k=0}^{n-1 } \left ( x^{m-1}p^{n-1}-[x^{m-1},p^k]p^{n - k-1 } + p^{n - k-1}[x^{m-1},p^k]+p^{n-1}x^{m-1 } \right)\\ & = \frac{im}{4}\sum_{k=0}^{n-1 } \left ( x^{m-1}p^{n-1}+p^{n-1}x^{m-1}+ [ p^{n - k-1},[x^{m-1},p^k ] ] \right)\\ & = \frac{imn}{4 } \left ( x^{m-1}p^{n-1}+p^{n-1}x^{m-1}\right)+ \frac{im}{4}\left ( \sum_{k=1}^{n-2 } [ p^{n - k-1},[x^{m-1},p^k ] ] \right)\\\end{aligned}\ ] ] as a result : @xmath56 -\frac{1}{n+1}\sum_{k=1}^{n-1}[p^{n - k},[x^m , p^k]]\ ] ] note that for @xmath57 , the summation term in the identity above is zero . also , due to the jacobi identity , we have @xmath58=[p^{k},[x^m , p^{n - k}]]$ ] , and this may also lead to some simplification depending on the value of @xmath59 . here , we shall illustrate the necessity for having better ( than any commonly used ) approximations . the approximations that we employ. Please generate the next two sentences of the article

are explicitly introduced below in this supplemental material . for instance , for a nested commutation approximation of an interaction strength @xmath60 and a dominant error term of @xmath61 , we would need @xmath62 operations corresponding to an eighth - order approximation . for comparison , note that it is also possible to use lloyd s method @xcite .

Suppose that you have an abstract for a scientific paper: we study centered and decentered nucleation of black holes in core - collapse of massive stars in binaries . by bekenstein s gravitational - radiation recoil mechanism , a newly nucleated black hole typically leaves the central core prematurely . with low probability , the black hole remains centered and matures to a high - mass black hole which spins rapidly if the binary is compact . grb030329/sn2003dh demonstrates that type ib / c supernovae are the parent population of long grbs , whose branching ratio is @xmath0 . we identify @xmath1 with the low probability of centered nucleation in compact binaries . decentered events are predicted to produce a single short burst in gravitational radiation . centered events are predicted to produce a second , long - burst in gravitational radiation powered by a luminous black hole . these signatures are of interest to ligo , virgo and tama . . And you have already written the first three sentences of the full article: grb030329/sn2003dh @xcite and grb980425/sn1998bw @xcite show that type ib / c supernovae are the parent population of long grbs . type ib / c sne are believed to represent core - collapse events of massive stars in compact binaries @xcite . they are probably part of a continuous sequence adjacent to type ii sne , ordered by increasing compactness of the binary in which the hydrogen ( ib / c ) and the helium ( ic ) envelope are removed in a common envelope phase @xcite .. Please generate the next two sentences of the article

the remaining naked star rotates rapidly at the orbital period by tidal spin - up . as the inactive iron - core succumbs to its own weight and that of the surrounding he - envelope , a rotating black hole nucleates during core - collapse @xcite . some of the binding energy liberated during gravitational collapse will be channeled to eject matter , producing an accompanying hydrogen ( and helium ) deficient type ib ( type ic ) supernova @xcite .

Suppose that you have an abstract for a scientific paper: let @xmath0 be an algebraically closed field of characteristic @xmath1 . let @xmath2 be a semi - direct product of the form @xmath3 where @xmath4 is a positive integer and @xmath5 is a prime distinct from @xmath6 . in this paper , we study galois covers @xmath7 ramified only over @xmath8 with galois group @xmath2 . we find the minimal genus of a curve @xmath9 which admits a covering map of this form and we give an explicit formula for this genus in terms of @xmath5 and @xmath6 . the minimal genus occurs when @xmath4 equals the order @xmath10 of @xmath5 modulo @xmath4 and we also prove that the number of curves @xmath9 of this minimal genus which admit such a covering map is at most @xmath11 when @xmath6 is odd . . And you have already written the first three sentences of the full article: let @xmath0 be an algebraically closed field of characteristic @xmath1 . in sharp contrast with the situation in characteristic @xmath12 , there exist galois covers @xmath7 ramified only over infinity . by abhyankar s conjecture @xcite , proved by raynaud and harbater @xcite , @xcite , a finite group @xmath2 occurs as the galois group of such a cover @xmath13 if and only if @xmath2 is quasi-@xmath6 , i.e. , @xmath2 is generated by @xmath6-groups .. Please generate the next two sentences of the article

this result classifies all the finite quotients of the fundamental group @xmath14 . it does not , however , determine the profinite group structure of @xmath14 because this fundamental group is an infinitely generated profinite group .

Suppose that you have an abstract for a scientific paper: this paper studies the joint support recovery of similar sparse vectors on the basis of a limited number of noisy linear measurements , _ i.e. _ , in a multiple measurement vector ( mmv ) model . the additive noise signals on each measurement vector are assumed to be gaussian and to exhibit different variances . the simultaneous orthogonal matching pursuit ( somp ) algorithm is generalized to weight the impact of each measurement vector on the choice of the atoms to be picked according to their noise levels . the new algorithm is referred to as somp - ns where ns stands for noise stabilization . to begin with , a theoretical framework to analyze the performance of the proposed algorithm is developed . this framework is then used to build conservative lower bounds on the probability of partial or full joint support recovery . numerical simulations show that the proposed algorithm outperforms somp and that the theoretical lower bound provides a great insight into how somp - ns behaves when the weighting strategy is modified . . And you have already written the first three sentences of the full article: the recovery of sparse signals of high dimensions on the basis of noisy linear measurements is an important problem in the field of signal acquisition and processing . when the number of linear observations is significantly lower than the dimension of the signal to be recovered , the signal recovery may exploit the property of sparsity to deliver correct results . the field of research that studies such problems is often referred to as _ compressed sensing _ or _ compressive sensing _ ( cs ) @xcite .. Please generate the next two sentences of the article

+ several computationally tractable methods to address cs problems have been developed in the last two decades @xcite . among them , greedy methods prove to be valuable choices as their complexity is significantly lower than that of algorithms based on @xmath0-minimization @xcite . + while many cs problems involve only one sparse signal and the corresponding _ measurement vector _ , _ i.e. _ , the vector gathering all the linear observations of this signal , some applications either require or at least benefit from the presence of several sparse signals and measurement vectors .

Suppose that you have an abstract for a scientific paper: the first step in the coherent control of a photoinduced binary reaction is bond making or photoassociation . we have recently demonstrated coherent control of bond making in multi - photon femtosecond photoassociation of hot magnesium atoms , using linearly chirped pulses [ levin et al . , arxiv:1411.1542 ] . the detected yield of photoassociated magnesium dimers was enhanced by positively chirped pulses which is explained theoretically by a combination of purification and chirp - dependent raman transitions . the yield could be further enhanced by pulse optimization resulting in pulses with an effective linear chirp and a sub - pulse structure , where the latter allows for exploiting vibrational coherences . here , we systematically explore the efficiency of phase - shaped pulses for the coherent control of bond making , employing a parametrization of the spectral phases in the form of cosine functions . we find up to an order of magnitude enhancement of the yield compared to the unshaped transform - limited pulse . the highly performing pulses all display an overall temporally increasing instantaneous frequency and are composed of several overlapping sub - pulses . the time delay between the first two sub - pulses almost perfectly fits the vibrational frequency of the generated intermediate wavepacket . these findings are in agreement with chirp - dependent raman transitions and exploitation of vibrational dynamics as underlying control mechanisms . . And you have already written the first three sentences of the full article: quantum coherent control of photo - induced processes @xcite directs a quantum system from its initial state to desired final state(s ) by manipulating interferences among coherent excitation pathways . when using strong femtosecond laser pulses , control can be realized based on the broad spectrum , high intensity and ultrashort duration of the pulses by tailoring their temporal shape @xcite . coherent control using tailored short pulses is nowadays successfully employed in many different areas of quantum physics , including photoionization and fragmentation , nuclear magnetic resonance and quantum information processing . however , the dream of coherently controlling photo - induced bimolecular chemical reactions @xcite which was at the origin of coherent control , still stands open .. Please generate the next two sentences of the article

for example , it is not yet understood under which conditions a bimolecular reaction can be controlled and which reaction mechanisms are particularly susceptible to control . this dream has attracted significant interest over the years including that of moshe shapiro @xcite since it holds the promise of creating a new type of photochemistry .

Suppose that you have an abstract for a scientific paper: luminosity upgrades of the fermilab tevatron @xmath0 collider have been shown to allow experimental detection of a standard model ( sm ) higgs boson up to @xmath1 gev via @xmath2 events . this limit nearly saturates the parameter space for many models of weak scale supersymmetry ( susy ) with a minimal particle content . it is therefore interesting to examine the susy higgs reach of future tevatron experiments . contours are presented of higgs boson reach for cern lep2 and tevatron luminosity upgrades for three models of weak scale susy : the minimal supersymmetric standard model ( mssm ) , the minimal supergravity model ( msugra ) and a simple gauge mediated susy breaking model ( gmsb ) . in each case we find a substantial gain in reach at the tevatron with integrated luminosity increasing from 10 fb@xmath3 to 25 - 30 fb@xmath3 . with the larger integrated luminosity , a higgs search at the tevatron should be able to probe essentially the entire parameter space of these models . while a discovery would be very exciting , a negative result would severely constrain our ideas about how weak scale supersymmetry is realized . * to appear in physical review d * . And you have already written the first three sentences of the full article: one of the mysteries of elementary particle physics is the origin of electroweak symmetry breaking ( ewsb ) . in the standard model ( sm ) , ewsb occurs via the higgs mechanism , a consequence of which is the existence of a fundamental scalar particle , the higgs boson @xmath4 @xcite . comparison of precision measurements of electroweak parameters with sm predictions indicates a preference for a light higgs boson @xmath5 gev @xcite .. Please generate the next two sentences of the article

the higgs boson has been searched for at collider experiments . the current best limit on its mass is @xmath6 gev from searches for @xmath7 at lep2@xcite .

Suppose that you have an abstract for a scientific paper: the vierbein ( tetrad ) fields for closed and open friedmann - robertson - walker cosmologies are hard to work out in most of the theories featuring absolute parallelism . the difficulty is traced in the fact that these theories are not invariant under local lorentz transformations of the vierbein . we illustrate this issue in the framework of @xmath0 theories and born - infeld determinantal gravity . in particular , we show that the early universe as described by the born - infeld scheme is singularity free and naturally inflationary as a consequence of the very nature of born - infeld gravitational action . . And you have already written the first three sentences of the full article: in the last decade a wide variety of modified theories of gravity has been studied with the aim of solving or smoothing some puzzling features of conventional gravity and cosmology . the reasons for considering such a modified gravitational schemes rely mainly on two damages that are intrinsic features of general relativity ( gr ) . on one hand , it is widely accepted by high energy physicists that the description of the gravitational field provided by general relativity must be doomed at scales of the order of the planck length , where the spacetime structure itself must be represented in terms of a quantum regime . on the other hand , and in the opposite extreme of the physical phenomena , gr also faces an intriguing dilemma in connection with the late cosmic speed up stage of the universe .. Please generate the next two sentences of the article

one of the newest extended theories of gravity is the so called @xmath0 gravity , which is a theory formulated in a spacetime possessing absolute parallelism @xcite . the first investigations within this framework can be traced back to refs .

Suppose that you have an abstract for a scientific paper: we have analyzed 3 observations of the high mass x - ray binary a0535 + 26 performed by the _ rossi x - ray timing explorer _ ( _ rxte _ ) 3 , 5 , and 6 months after the last outburst in 2011 february . we detect pulsations only in the second observation . the 320 kev spectra can be fit equally well with either an absorbed power law or absorbed thermal bremsstrahlung model . re - analysis of 2 earlier _ rxte _ observations made 4 years after the 1994 outburst , original _ bepposax _ observations 2 years later , re - analysis of 4 _ exosat _ observations made 2 years after the last 1984 outburst , and a recent _ xmm - newton _ observation in 2012 reveal a stacked , quiescent flux level decreasing from @xmath02 to @xmath1 ergs @xmath2 s@xmath3 over 6.5 years after outburst . detection of pulsations during half of the quiescent observations would imply that accretion onto the magnetic poles of the neutron star continues despite the fact that the circumstellar disk may no longer be present . the accretion could come from material built - up at the corotation radius or from an isotropic stellar wind . . And you have already written the first three sentences of the full article: a0535 + 26 is a be / x - ray binary system , discovered by _ ariel v _ during a giant outburst in 1975 @xcite . the binary system consists of the neutron star pulsar a0535 + 26 and o9.7-b0 iiie optical companion hde245770 @xcite .. Please generate the next two sentences of the article

the neutron star moves in an eccentric orbit with _ = 0.47 , an orbital period @xmath4 = 111.07@xmath50.07 days , and exhibiting a pulse period of @xmath0103.25 s ( * ? ? ?

Suppose that you have an abstract for a scientific paper: we investigate the ground state of the one - dimensional fermionic system enclosed in a hard - wall trap with attractive contact @xmath0-wave interactions . based on the bethe ansatz method , the explicit wave function is derived by numerically solving the bethe ansatz equations for the full physical regimes ( @xmath1 ) . with the exact wave function some quantities which are important in many - body physics are obtained , including the one - body density matrix and the momentum distribution of the ground state for finite system . it is shown that the shell structure of the density profiles disappears with the increase of the interaction and in the fermionic tonks - girardeau ( ftg ) limit the density distribution shows the same behavior as that of an ideal bose gas . however the one - body density matrix and the momentum distribution exhibit completely different structures compared with their bosonic counterparts . . And you have already written the first three sentences of the full article: experimental realization of trapped one - dimensional ( 1d ) cold atom systems @xcite are triggering more and more theoretical efforts to study the 1d many - body physics beyond the mean - field theory . for the ultracold quantum gases tightly confined in waveguides , the dynamics are effectively described by a 1d model due to the radial degrees of freedom are frozen @xcite . further , the ability of tuning the effective 1d interactions by feshbach resonance allows experimental access to the very strongly interacting regime where correlation effects are greatly enhanced @xcite . in the limit of the tonks - girardeau ( tg ) @xcite gas with. Please generate the next two sentences of the article

effective coupling constant @xmath2 , the many - body problem of a tg gas can be mapped to that of a free fermi gas by the bose - fermi mapping , which has been verified by two experimental groups @xcite . this bose - fermi duality was generalized to show the equivalence between a 1d fermionic system and a bosonic one with the reversed role of strong and weak couplings @xcite .

Suppose that you have an abstract for a scientific paper: using arcminute microkelvin imager ( ami ) sz observations towards ten clash clusters we investigate the influence of cluster mergers on observational galaxy cluster studies . although selected to be largely relaxed , there is disagreement in the literature on the dynamical states of clash sample members . we analyse our ami data in a fully bayesian way to produce estimated cluster parameters and consider the intrinsic correlations in our nfw / gnfw - based model . varying pressure profile shape parameters , illustrating an influence of mergers on scaling relations , induces small deviations from the canonical self - similar predictions in agreement with simulations of @xcite who found that merger activity causes only small scatter perpendicular to the relations . we demonstrate this effect observationally using the different dependencies of sz and x - ray signals to @xmath0 that cause different sensitivities to the shocking and/or fractionation produced by mergers . plotting @xmath1@xmath2 relations ( where @xmath3 ) derived from ami sz and from @xmath4 x - ray gives ratios of ami and @xmath4 @xmath1 and @xmath2 estimates that indicate movement of clusters _ along _ the scaling relation , as predicted by @xcite . clusters that have moved most along the relation have the most discrepant @xmath5 and @xmath6 estimates : all the other clusters ( apart from one ) have sz and x - ray estimates of @xmath2 , @xmath7 and @xmath1 that agree within @xmath8 . we use sz vs x - ray discrepancies in conjunction with @xmath4 maps and @xmath6 profiles , making comparisons with simulated cluster merger maps in @xcite , to identify disturbed members of our sample and estimate merger stages . = 1 [ firstpage ] galaxies : clusters : general methods : observational techniques : interferometric large - scale structure of the universe . lcclcluster & relaxed & unrelaxed & notes + + a611 & & & widely agreed relaxed , see e.g. @xcite , @xcite + & & & relaxed : e.g. classified ` non - distorted '.... And you have already written the first three sentences of the full article: physical parameters of glaxy clusters , such as total mass and gas mass , are commonly studied through scaling relations . these relations assume that both growing and mature clusters are relaxed , self - similar systems such that relations between e.g. @xmath9 , @xmath10 , @xmath11 , @xmath2 , @xmath7 , etc . are simple power laws ( see e.g. @xcite and @xcite for a recent review ) . deviations from hydrostatic equilibrium ( hse ) ( or from virialisation ) and self - similarity during cluster mergers. Please generate the next two sentences of the article

will cause scatter around the scaling relations . studies in the literature aim to use these relations to make accurate determinations of e.g. total cluster mass , and therefore often focus on minimising the scatter either by careful sample selection of low - redshift , relaxed clusters ( e.g. , , @xcite , @xcite ) , or by finding a particularly low - scatter mass proxy ( e.g. @xcite , , , @xcite ) .

Suppose that you have an abstract for a scientific paper: i review the results of hadron spectroscopy calculations from lattice qcd for an intended audience of low energy hadronic physicists . i briefly introduce the ideas of numerical lattice qcd . the various systematic errors , such as the lattice spacing and volume dependence , in lattice qcd calculations are discussed . in addition to the discussion of the properties of ground state hadrons , i also review the small amount of work done on the spectroscopy of excited hadrons and the effect of electromagnetic fields on hadron masses . i also discuss the attempts to understand the physical mechanisms behind hadron mass splittings . . And you have already written the first three sentences of the full article: qcd at low energies is hard to solve , perhaps too hard for mere mortals to solve , even when assisted with the latest supercomputers . qcd is the theory that describes the interactions of quarks and gluons . qcd has been well tested in high energy scattering experiments where perturbation theory is valid .. Please generate the next two sentences of the article

however , qcd should also describe nuclear physics and the mass spectrum of hadrons . hadron masses depend on the coupling ( @xmath0 ) like @xmath1 hence perturbation theory ca nt be used to compute the masses of hadrons such as the proton . the only technique that offers any prospect of computing masses and matrix elements non - perturbatively , from first principles , is lattice qcd . in lattice

Suppose that you have an abstract for a scientific paper: motivated by the phenomenology of transport through the golgi apparatus of cells , we study a multi - species model with boundary injection of one species of particle , interconversion between the different species of particle , and driven diffusive movement of particles through the system by chipping of a single particle from a site . the model is analysed in one dimension using equations for particle currents . it is found that , depending on the rates of various processes and the asymmetry in the hopping , the system may exist either in a steady phase , in which the average mass at each site attains a time - independent value , or in a `` growing '' phase , in which the total mass grows indefinitely in time , even in a finite system . the growing phases have interesting spatial structure . in particular , we find phases in which some spatial regions of the system have a constant average mass , while other regions show unbounded growth . . And you have already written the first three sentences of the full article: [ [ section ] ] living cells possess multiple trafficking pathways , which have in common , a regulated flux of cargo molecules , such as proteins and lipids , moving through and processed within , organized compartments or organelles . for instance , the _ secretory pathway _ consists of molecules that move from the endoplasmic reticulum ( er ) to the cell surface via an organelle system called the golgi apparatus @xcite . the golgi apparatus itself consists of distinct sub - compartments known as cisternae .. Please generate the next two sentences of the article

proteins and lipids arrive from the er , enter through one face of the golgi and undergo several chemical reactions ( processing ) ; the modified products then leave through the other face to mainly target the cell surface . [ [ section-1 ] ] there has been much discussion about what drives the flux of molecules through the golgi @xcite .

Suppose that you have an abstract for a scientific paper: we have obtained a full suite of _ spitzer _ observations to characterize the debris disk around hr 8799 and to explore how its properties are related to the recently discovered set of three massive planets orbiting the star . we distinguish three components to the debris system : ( 1 ) warm dust ( t @xmath0 150 k ) orbiting within the innermost planet ; ( 2 ) a broad zone of cold dust ( t @xmath0 45 k ) with a sharp inner edge , orbiting just outside the outermost planet and presumably sculpted by it ; and ( 3 ) a dramatic halo of small grains originating in the cold dust component . the high level of dynamical activity implied by this halo may arise due to enhanced gravitational stirring by the massive planets . the relatively young age of hr 8799 places it in an important early stage of development and may provide some help in understanding the interaction of planets and planetary debris , an important process in the evolution of our own solar system . . And you have already written the first three sentences of the full article: rapid progress has been made in the past decade in discovering other planetary systems and in building theories for their formation and evolution . more than 300 extrasolar planets have been found through measuring stellar radial velocities and about 60 planets have been observed to transit their stars ( extrasolar planets encyclopaedia , http://exoplanet.eu/ ) . however , these techniques are optimal in finding systems dramatically different from the solar system , with giant planets in orbits very close to their stars .. Please generate the next two sentences of the article

there are two primary avenues for probing systems with planets that might have structures more analogous to that of the solar system . first , giant planets have recently been imaged around fomalhaut @xcite and hr 8799 @xcite in orbits with radii of tens of au .

Suppose that you have an abstract for a scientific paper: we present a lattice boltzmann algorithm based on an underlying free energy that allows the simulation of the dynamics of a multicomponent system with an arbitrary number of components . the thermodynamic properties , such as the chemical potential of each component and the pressure of the overall system , are incorporated in the model . we derived a symmetrical convection diffusion equation for each component as well as the navier stokes equation and continuity equation for the overall system . the algorithm was verified through simulations of binary and ternary systems . the equilibrium concentrations of components of binary and ternary systems simulated with our algorithm agree well with theoretical expectations . . And you have already written the first three sentences of the full article: multicomponent systems are of great theoretical and practical importance . an example of an important ternary system , that inspired the current paper , is the formation of polymer membranes through immersion precipitation @xcite . in this process a polymer - solvent mixture is brought in contact with a non - solvent . as the non - solvent diffuses into the mixture , the mixture phase - separates , leaving behind a complex polymer morphology which depends strongly on the processing conditions .. Please generate the next two sentences of the article

the dependence of the morphology on the parameters of the system is as yet poorly understood . preliminary lattice boltzmann simulations of this system exist @xcite

Suppose that you have an abstract for a scientific paper: the origin of subdwarf b ( sdb ) stars is not fully understood yet since it requires high mass loss at the red giant stage . sdbs in close binary systems are formed via common envelope ejection , but the origin of apparently single sdb stars remains unclear . substellar companions may be able to trigger common envelope ejection and help forming sdbs that appear to be single . + using a sample of high resolution spectra we aim at detecting small radial velocity ( rv ) shifts caused by such low mass ( sub-)stellar companions . the rvs are measured with high accuracy using sharp metal lines . our goal is to test the theoretical predictions and put constraints on the population of the lowest mass companions to sdb stars . address = dr . karl remeis observatory & ecap , astronomical institute , friedrich - alexander university erlangen - nuremberg , sternwartstr . 7 , d-96049 bamberg , germany address = dr . karl remeis observatory & ecap , astronomical institute , friedrich - alexander university erlangen - nuremberg , sternwartstr . 7 , d-96049 bamberg , germany address = dr . karl remeis observatory & ecap , astronomical institute , friedrich - alexander university erlangen - nuremberg , sternwartstr . 7 , d-96049 bamberg , germany address = australian astronomical observatory , po box 296 , epping , nsw , 1710 , australia . And you have already written the first three sentences of the full article: subluminous stars are considered to be core helium - burning objects with a thin hydrogen shell . in a hertzsprung - russell diagram these stars are situated on the extreme horizontal branch ( ehb ) . the evolution of these stars is far from understood since the formation of an sdb requires extreme mass loss at the tip of the rgb . the mechanism leading to this mass loss is still under debate @xcite .. Please generate the next two sentences of the article

formation scenarios can be roughly divided into single star and binary channels . about 50% of the known sdbs are found to be in close binaries with periods of few hours to several days consistent with the predictions of the common envelope ( ce ) ejection scenario @xcite .

Suppose that you have an abstract for a scientific paper: we present the reduced operator approximation : a simple , physically transparent and computationally efficient method of modelling open quantum systems . it employs the heisenberg picture of the quantum dynamics , which allows us to focus on the system degrees of freedom in a natural and easy way . we describe different variants of the method , low- and high - order ( including the interaction operators ) , defining them for either general quantum harmonic oscillators baths or specialising them for independent baths with lorentzian spectral densities . the method captures the decoherence of the system interacting with the bath , while conserving the total energy . the wide range of the method applicability is presented on the example of systems coupled to different baths with different strengths , and compared with the exact pseudomode and the popular quantum state diffusion approach . our results suggest that quantum coherence effects persist in open quantum systems for much longer times than previously thought . . And you have already written the first three sentences of the full article: the beginning of twentieth century launched a series of major paradigm shifts which heralded the era of modern physics . it will perhaps be surprising to the modern reader that in the advent of the revolutionary einsteinian theory of relativity , maxwell and boltzmann s kinetic theory and planck s hypothesis of quanta , the scientific world was not convinced of the fact that matter is grainy and can not be continuously divided ad infinitum @xcite . the seed of doubt was planted by the renowned scottish botanist , robert brown , who noticed in 1827 that pollen in water suspension which he examined under his microscope displayed a very rapid , irregular , zigzag motion .. Please generate the next two sentences of the article

the mystery of the `` vital force '' driving the brownian motions remained unsolved for nearly 80 years , evading the pincer of conventional physics . the answer came from einstein and smoluchowski , who showed how the behaviour of mechanical objects is driven by the statistical properties of thermal noise , postulating the existence of molecules in the fluid and linking the diffusion strength of their motion to the friction acting on a body moving in the fluid @xcite .

Suppose that you have an abstract for a scientific paper: this study investigates the modifications of the thermal spectrum , at low frequency , induced by an external damping on a system in heat contact with internal fluctuating impurities . those impurities can move among locations and their oscillations are associated with a loss function depending on the model . the fluctuation properties of the system are provided by a potential function shaped by wells , in such a way that jumps between the stationary positions are allowed . the power spectral density associated with this dissipation mechanism shows a @xmath0 tail . the interest of this problem is that many systems are characterized by a typical @xmath0 spectral tail at low frequency . the model presented in this article is based on a threshold type behaviour and its generality allows applications in several fields . the effects of an external force , introduced to produce damping , are studied by using both analytical techniques and numerical simulations . the results obtained with the present model show that no reduction of the power spectral density is appreciable below the main peak of the spectral density . + pacs numbers : 05.40-a , 05.10-a . And you have already written the first three sentences of the full article: since gravitational wave interferometers will sense the passage of a gravitational wave as a difference in the light path between mirrors in the two arms , every kind of excitation is a noise source . cooling the mirrors of these detectors , by measuring and controlling with a feedback loop the principal fundamental motions that may be thermally excited , may offer a means to reduce thermal noise . with this motivation in mind , we investigated models that generate frequency spectra with a tail @xmath0 for @xmath1 .. Please generate the next two sentences of the article

this dependence is found in many completely different physical systems , suggesting a possible underlying simple mechanism . the typical physical parameters are different for each of them , and especially the characteristic microscopic quantities .

Suppose that you have an abstract for a scientific paper: we discuss @xmath0-dimensional dynamical wormholes in an evolving cosmological background with a throat expanding with time . these solutions are examined in the general relativity framework . a linear relation between diagonal elements of an anisotropic energy - momentum tensor is used to obtain the solutions . the energy - momentum tensor elements approach the vacuum case when we are far from the central object for one class of solutions . finally , we discuss the energy - momentum tensor which supports this geometry , taking into account the energy conditions . . And you have already written the first three sentences of the full article: wormholes are hypothetical objects which connect two distant parts of the same spacetime or two different spacetimes by a throat - like object which has the minimum radius of the spacetime . although a wormhole solution first entered the physics literature in 1916 @xcite , the concept was first considered seriously in 1935 by einstein and rosen @xcite which was later called einstein - rosen bridge but the word wormhole was first time coined by wheeler @xcite in 1957 . a more interesting analysis of wormholes was performed by morris and thorne in 1988 and they presented a new kind of wormhole ( traversable wormhole ) for the first time @xcite .. Please generate the next two sentences of the article

it was known from before that matter we need to support such a geometry violates the weak and strong energy conditions near the throat @xcite . morris and thorne reconsidered these conditions for a traversable wormhole @xcite . since the matter that supports this geometry does nt satisfy the common energy conditions they called it exotic. an example of exotic matter is matter with negative energy density @xcite .

Suppose that you have an abstract for a scientific paper: a generic assumption of ionization models of quasar absorption systems is that radiation from local sources is negligible compared with the cosmological background . we test this assumption and find that it is unlikely to hold for absorbers as rare as lyman limit systems . assuming that the absorption systems are gas clouds centered on sources of radiation , we derive analytic estimates for the cross - section weighted moments of the flux seen by the absorbers , of the impact parameter , and of the luminosity of the central source . in addition , we compute the corresponding medians numerically . for the one class of absorbers for which the flux has been measured : damped ly@xmath0 systems at @xmath1 , our prediction is in excellent agreement with the observations if we assume that the absorption arises in clouds centered on lyman - break galaxies . finally , we show that if lyman - break galaxies dominate the uv background at redshift 3 , then consistency between observations of the uv background , the uv luminosity density from galaxies , and the number density of lyman limit systems requires escape fractions of order 10 percent . . And you have already written the first three sentences of the full article: the intergalactic medium ( igm ) is thought to be photo - ionized by the uv radiation emitted by galaxies and quasars . models of quasar absorption systems generally assume that the gas is exposed only to the mean background radiation that pervades the igm . however , given that this background is produced by discrete sources , it can not be strictly uniform . the effect of fluctuations in the uv background on the statistics of the forest of weak hi ly@xmath0 absorption lines , seen in the spectra of distant quasars , has been the subject of a large number of papers ( e.g. , zuo 1992 ; fardal & shull 1993 ; croft et al . 1999 , 2002 ;. Please generate the next two sentences of the article

gnedin & hamilton 2002 ; linder et al . 2003 ; meiksin & white 2003 , 2004 ; croft 2004 ; mcdonald et al .

Suppose that you have an abstract for a scientific paper: we have demonstrated an atom - optical lens , with the advantage of a small scale and flexible adjustment of the parameters , created by far red - detuned gaussian laser beam perpendicular to the propagation direction of the cold atomic cloud . this work presents the focusing and collimation effect of a cold atomic cloud , with uniform translational velocity and with vanishing initial translational velocity in gravity respectively , by the atom - optical lens . the object - image relation , focal length and the collimation effect of the atom - optical lens have been analyzed both theoretically and experimentally . . And you have already written the first three sentences of the full article: with the development of laser cooling and evaporative cooling techniques , it is easy to obtain ultracold atomic clouds at the temperature order of 1@xmath0k @xcite . this kind of ultralow temperature atomic cloud is suitable as a medium in atom optics studies meystre , pr240 - 143 . atom - optical lens is one of the fundamental atom - optical elements , which can focus , collimate , image and transmit the atom beam .. Please generate the next two sentences of the article

therefore it has been implemented in many ways , such as , atom lithography , atom interferometry and atom interference . up to now two kinds of atomic lens , based on magnetic or far - detuned optical fields , have been developed .

Suppose that you have an abstract for a scientific paper: we discuss the use of the bicoherence - a measure of the phase coupling of oscillations at different frequencies - as a diagnostic between different models for high frequency quasi - periodic oscillations from galactic black hole candidates . we show that this statistic is capable of finding qualitative distinctions between different hot spot models which produce nearly identical fourier power density spectra . finally , we show that proposed new timing missions should detect enough counts to make real use of this statistic . [ firstpage ] epsf methods : data analysis , methods : statistical , binaries : close , black hole physics , x - rays : binaries , stars : oscillations . And you have already written the first three sentences of the full article: it has long been hoped that x - ray binaries and active galactic nuclei would prove to be good laboratories for testing general relativity . the two most promising lines of attack for disentangling relativistic effects from the physics of accretion disks and of radiative transfer are high resolution spectroscopy of emission lines ( see e.g. reynolds & nowak 2003 for a review ) and studies of high frequency quasi - periodic oscillations ( see e.g. van der klis 2004 for a review ) . recently , high frequency quasi - periodic oscillations ( hfqpos ) have been found in low mass x - ray binaries for which the black hole masses are reasonably well measured . in one case in particular , a frequency has been identified which is too large to be a keplerian orbit around a schwarzschild black hole ( strohmayer 2001 ) .. Please generate the next two sentences of the article

furthermore , a pattern has begun emerging where these high frequency qpos are found in pairs with 2:3 ratios of frequencies . this was first pointed out by abramowicz & kluzniak ( 2001 ) , based on combining observational results from strohmayer ( 2001 ) and remillard et al .

Suppose that you have an abstract for a scientific paper: similar to the three - qubit greenberger - horne - zeilinger ( ghz ) symmetry we explore the four - qubit ghz symmetry group and its subgroup called restricted ghz symmetry group . while the set of symmetric states under the whole group transformation is represented by three real parameters , the set of symmetric states under the subgroup transformation is represented by two real parameters . after comparing the symmetric states for whole and subgroup , the entanglement is examined for the latter set . it is shown that the set has only two slocc classes , @xmath0 and @xmath1 . extension to the multi - qubit system is briefly discussed . . And you have already written the first three sentences of the full article: quantum entanglement@xcite is the most important notion in quantum technology ( qt ) and quantum information theory ( qit ) . as shown for last two decades it plays a crucial role in quantum teleportation@xcite , superdense coding@xcite , quantum cloning@xcite , and quantum cryptography@xcite . it is also quantum entanglement , which makes the quantum computer outperform the classical one@xcite .. Please generate the next two sentences of the article

thus , in order to develop qt and qit it is essential to understand how to quantify and how to characterize the multipartite entanglement . since the quantum entanglement is a non - local property of given multipartite quantum state , it should be invariant under the local unitary ( lu ) transformations , i.e. the unitary operations acted independently on each of the subsystems .

Suppose that you have an abstract for a scientific paper: the polarization dependence of nonequilibrium transitions in a multistable cavity - polariton system is studied under a nanosecond long resonant optical excitation at the normal and magic angle incidences with various polarizations of the pump beam . the temporal correlations between the frequency , intensity , and optical polarization of the intra - cavity field , which all undergo sharp threshold - like changes due to the spin dependent interaction of cavity polaritons , are visualized . the observed dynamics can not be reproduced within the conventional semi - classical model based on the gross - pitaevskii equations . to explain the observed phenomena , it is necessary to take into account the unpolarized exciton reservoir which brings on additional blueshift of bright excitons , equal in the @xmath0 and @xmath1 polarization components . this model explains the effect of polarization instability under both pulsed and continuous wave resonant excitation conditions , consistently with the spin ring pattern formation that has recently been observed under gaussian shaped excitation . . And you have already written the first three sentences of the full article: cavity polaritons are bound light - matter states that appear due to the strong coupling of 2d excitons and photons in semiconductor microcavities.@xcite the optically driven system of polaritons behaves like a weakly imperfect bose gas , which results in a spectacular row of polariton collective phenomena such as multistability,@xcite parametric scattering,@xcite pattern formation,@xcite self - organization effects,@xcite dynamical bose - einstein condensation.@xcite polariton multistability attracts much attention as a potential candidate for very fast picosecond range optical switching on a micron size scale.@xcite moreover , the sharp transitions in intra - cavity field , stemming from the multistability , can proceed concurrently with inter - mode parametric scattering , which determines interesting ways of polariton self - organization under pumping near the inflection point of the lower polariton branch ( the `` magic angle'').@xcite the polariton bistability has recently been studied in the `` scalar '' approximation neglecting the spin degrees of freedom.@xcite because of the mutual interaction of polaritons , their energy effectively depends on the intra - cavity field magnitude . the repulsion between excitons leads to the blueshift of polariton energy . when the pump is itself blue - detuned from the polariton resonance , a strong positive feedback loop between the resonance energy and the field amplitude is created in a certain range of system parameters , resulting in sharp jumps in the intra - cavity field and , hence , in the cavity transmission .. Please generate the next two sentences of the article

consequently , the transmission signal can exhibit a prominent hysteresis in the dependence on continuous - wave ( cw ) pump intensity.@xcite the response of the optically excited polariton system becomes more complicated with allowance made for exciton spin degrees of freedom ( that corresponds to arbitrary optical polarization of the intra - cavity field ) . in the general case the system has up to four stable states under a given cw pump , whereas the actual state of the system is determined by the history of the excitation process.@xcite in critical points , where a number and/or stability of stationary solutions change , the system can exhibit sharp jumps in both the amplitude and polarization of the intra - cavity field . under a spatially inhomogeneous ( e.g. , gaussian shaped ) cw excitation

Suppose that you have an abstract for a scientific paper: a mesoscopic multi - particle collision model for fluid dynamics is generalized to incorporate the chemical reactions among species that may diffuse at different rates . this generalization provides a means to simulate reaction - diffusion dynamics of complex reactive systems . the method is illustrated by a study of cubic autocatalytic fronts . the mesoscopic scheme is able to reproduce the results of reaction - diffusion descriptions under conditions where the mean field equations are valid . the model is also able to incorporate the effects of molecular fluctuations on the reactive dynamics . . And you have already written the first three sentences of the full article: mesoscopic models provide coarse - grained descriptions of the dynamics of systems that neglect certain details at microscopic scales while retaining essential dynamical features at mesoscopic and macroscopic scales . consequently , a convenient way to study of the dynamics of complex systems over a large range of interesting space and time scales is through the use of such models . in physical and biological systems we often encounter situations where mean field descriptions of reactions break down and molecular fluctuations play an important role in determining the character of the system s dynamics . such effects are especially relevant for reactions taking place in nano - scale domains or biochemical reactions at the cellular level. Please generate the next two sentences of the article

. fluctuations also play a role in far - from - equilibrium systems near bifurcation points or when the system behaves chaotically since the system is especially susceptible to perturbations in such regimes . @xcite mesoscopic models are able to capture the influence of such molecular fluctuations on the dynamics .

Suppose that you have an abstract for a scientific paper: we present the first high - resolution near - infrared images of the edge - on silhouette circumstellar disk , orion 114 - 426 , made using nicmos on the _ hubble space telescope_. images taken against the bright nebular background of the ionized hydrogen pa@xmath0 line at 1.87 show the major axis of the disk to be approximately 20% smaller than at 0.6 , from which we deduce the structure of the edge of the disk . continuum images of diffuse polar lobes above and below the plane of the disk show a morphology and evolution with wavelength consistent with predictions for reflection nebulae in a diffuse envelope with large polar cavities , surrounding a thin , massless , keplerian disk , centered on an otherwise hidden central star . we make use of our observations and reasonable assumptions about the underlying disk structure to show that the disk mass is at least 10 and plausibly @xmath1 . 6.25 in 8.9 in subject headings : accretion , accretion disks circumstellar matter ism : individual ( orion nebula ) stars : formation , pre - main sequence infrared : ism : continuum , lines and bands . And you have already written the first three sentences of the full article: the discovery of a family of circumstellar disks seen as dark silhouettes in projection against the orion nebula using the _ hubble space telescope _ provided strong confirmation of the disk paradigm of star formation ( odell 1993 ; odell & wen 1994 ; mccaughrean & odell 1996 [ mo96 ] ) . the disks range in diameter from 501000au , and thus the @xmath250au ( 0.1 arcsec at 450pc ) resolution of the hst observations was sufficient to examine their structure directly at optical wavelengths . an important finding was that the radial surface density profiles appear to be abruptly truncated at some outer radius , perhaps due to external effects from the surrounding region and dense cluster ( mo96 ) , and more detailed examination of this transition zone should lead to a greater understanding of the evolution of disks in harsh environments .. Please generate the next two sentences of the article

the discovery images were obtained over a relatively narrow wavelength range ( 50076585 ) , and further insight should be possible through hst observations at shorter and longer wavelengths . in the blue / near - uv ( @xmath220004000 ) , the spatial resolution approaches @xmath215au , while increased dust opacity at these wavelengths should also allow more tenuous structures to be traced to larger radii .

Suppose that you have an abstract for a scientific paper: matrices are said to behave as free non - commuting random variables if the action which governs their dynamics constrains only their eigenvalues , i.e. depends on traces of powers of individual matrices . the authors use recently developed mathematical techniques in combination with a standard variational principle to formulate a new variational approach for matrix models . approximate variational solutions of interacting large - n matrix models are found using the free random matrices as the variational space . several classes of classical and quantum mechanical matrix models with different types of interactions are considered and the variational solutions compared with exact monte carlo and analytical results . impressive agreement is found in a majority of cases . . And you have already written the first three sentences of the full article: the main motivation behind this work lay in developing approximate analytical tools for dealing with the long range physics of quantum chromodynamics . the large-@xmath0 approximation is an attractive candidate for this project . initiated by t hooft , ref .. Please generate the next two sentences of the article

@xcite , it was immediately applied to solve large-@xmath1 1 + 1 dimensional qcd , refs . @xcite , @xcite , @xcite , @xcite and led to extremely fruitful phenomenological insights and models , refs .

Suppose that you have an abstract for a scientific paper: by subjecting a dynamical system to a series of short pulses and varying several time delays we can obtain multidimensional characteristic measures of the system . multidimensional kullback - leibler response function ( klrf ) , which are based on the kullback - leibler distance between the initial and final states , are defined . we compare the klrf , which are nonlinear in the probability density , with ordinary response functions ( orf ) obtained from the expectation value of a dynamical variable , which are linear . we show that the klrf encode different level of information regarding the system s dynamics . for overdamped stochastic dynamics two dimensional klrf shows a qualitatively different variation with the time delays between pulses , depending on whether the system is initially in a steady state , or in thermal equilibrium . . And you have already written the first three sentences of the full article: one of the most common ways to investigate the properties of a dynamical system is to study how it responds to controlled external perturbations . the response of a system to a weak perturbing field is related to its equilibrium fluctuations by the celebrated fluctuation dissipation relation @xcite . the response provides a direct measure of system dynamics and fluctuations . in a time - domain response measurement. Please generate the next two sentences of the article

one uses a series of impulsive perturbations ( fig . [ fig1 ] ) and records some property of the system as a function of their time - delays .

Suppose that you have an abstract for a scientific paper: we review our experiments on the electronic transport properties of atomic contacts between metallic electrodes , in particular superconducting ones . despite ignorance of the exact atomic configuration , these ultimate quantum point contacts can be manipulated and well characterized in - situ . they allow performing fundamental tests of the scattering theory of quantum transport . in particular , we discuss the case of the josephson effect . atomic contacts , superconductivity , quantum transport 74.45.+c , 74.50.+r , 73.23.-b . And you have already written the first three sentences of the full article: for significant quantum effects to appear in the transport properties of a conductor , it must be shorter than the distance over which an electron propagates without losing its quantum coherence , which for usual metals at low temperatures ( < 1k ) is on the order of microns . the exploration of this quantum transport regime started in the early 1980s with the observation of aharonov - bohm interferences in submicron metallic rings @xcite . a very powerful point of view , put forward by r. landauer @xcite , describes a transport experiment across a coherent conductor as the scattering of the quantum electronic waves injected by the contact probes . in other words ,. Please generate the next two sentences of the article

the conductor is viewed as an electronic waveguide , whose modes , called `` conduction channels '' , are each characterized by a transmission probability . for example , the total conductance is given by the famous landauer formula : @xmath0 , where @xmath1 is the number of channels , the @xmath2 are the individual transmission probabilities , and @xmath3 the conductance quantum . in fact , in systems with non - interacting quasiparticles all transport quantities can be expressed in terms of the transmission probability set @xmath4 , which is viewed in this framework as the personal identity number ( pin code ) of the conductor @xcite . for most systems ,