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Suppose that you have an abstract for a scientific paper: the compressibility , zero sound dispersion , and effective mass of a gas of fermionic dipolar molecules is calculated at finite temperature for one- , two- , and three - dimensional uniform systems , and in a multilayer quasi - two - dimensional system . the compressibility is nonmonotonic in the reduced temperature , @xmath0 , exhibiting a maximum at finite temperature . this effect might be visible in a quasi - low - dimensional experiment , providing a clear signature of the onset of many - body quantum degeneracy effects . the collective mode dispersion and effective mass show similar nontrivial temperature and density dependence . in a quasi - low - dimensional system , the zero sound mode may propagate at experimentally attainable temperatures . . And you have already written the first three sentences of the full article: the study of ultracold atomic systems has received much attention in recent years , motivated largely by the prospect of realizing novel strongly correlated many - body physics . a series of remarkable experimental breakthroughs have produced an extremely well - controlled physics playground @xcite . the latest breakthrough is the ability to associate atoms via a feshbach resonance to form ultracold molecules in the ro - vibrational ground state @xcite , and the jila group has achieved a nearly degenerate gas of ground state polar molecules @xcite .. Please generate the next two sentences of the article

this is a true milestone in the program , since strong dipolar interactions between degenerate molecules in the presence of an external electric field allow for the design of exotic hamiltonians @xcite and are expected to give rise to exciting phenomena including roton softening @xcite , supersolidity @xcite , artificial photons @xcite , bilayer quantum phase transitions @xcite , and multi - layer self - assembled chains @xcite for bosonic molecules , and spontaneous interlayer superfluidity @xcite , itinerant ferroelectricity @xcite , fermi liquid anisotropy @xcite , fractional quantum hall effect @xcite , wigner crystallization @xcite , biaxial nematic phase @xcite , topological superfluidity @xcite , and a @xmath1 topological phase @xcite for fermionic molecules . most , if not all , of these novel quantum phases will require temperatures on the order of @xmath2 or less ( with @xmath3 the fermi temperature ) , which will require further experimental advance .

Suppose that you have an abstract for a scientific paper: the iron arsenide rbfe@xmath0as@xmath0 with the thcr@xmath0si@xmath0-type structure is found to be a bulk superconductor with @xmath1 k. the onset of diamagnetism was used to estimate the upper critical field @xmath2 , resulting in @xmath3 t / k and an extrapolated @xmath4 t. as a new representative of iron pnictide superconductors , superconducting rbfe@xmath0as@xmath0 contrasts with bafe@xmath0as@xmath0 , where the fermi level is higher and a magnetic instability is observed . thus , the solid solution series ( rb , ba)fe@xmath0as@xmath0 is a promising system to study the cross - over from superconductivity to magnetism . rbfe@xmath0as@xmath0 , iron pnictides , upper critical field , transition temperature , superconductivity 74.70.dd , 74.25.op . And you have already written the first three sentences of the full article: the family of iron oxyarsenide @xmath5feaso@xmath6f@xmath7 ( @xmath5 = lanthanide element ) exhibits superconductivity with a maximum @xmath8 up to 56 k @xcite . additionally , the iron - arsenide compounds @xmath9fe@xmath0as@xmath0 ( @xmath9 = alkaline earth element ) , crystallizing in the thcr@xmath0si@xmath0-type structure , are known to become superconducting with @xmath8 s up to 38 k upon alkali metal substitution for the @xmath9 element @xcite , or partial transition metal substitution for fe @xcite . in contrast to undoped bafe@xmath0as@xmath0 with a magnetic ground state , superconductivity with relatively low @xmath8 s was reported in the undoped alkali metal iron - arsenides kfe@xmath0as@xmath0 ( @xmath10 k ) and csfe@xmath0as@xmath0 ( @xmath1 k ) @xcite . interestingly , rbfe@xmath0as@xmath0 is known to exist as well @xcite , although its physical properties have not been reported so far . here. Please generate the next two sentences of the article

we report on the superconductivity in undoped alkali metal iron arsenide rbfe@xmath0as@xmath0 . as@xmath0 polycrystalline sample , measured in a magnetic field of 1 mt . superconductivity sets in at @xmath11 k. ] , here for 1 mt and 200 mt , measured in the zfc mode .

Suppose that you have an abstract for a scientific paper: due to the broadcast nature of wireless medium , wireless communication is extremely vulnerable to eavesdropping attack . physical - layer security is emerging as a new paradigm to prevent the eavesdropper from interception by exploiting the physical characteristics of wireless channels , which has recently attracted a lot of research attentions . in this paper , we consider the physical - layer security in cooperative wireless networks with multiple decode - and - forward ( df ) relays and investigate the best relay selection in the presence of eavesdropping attack . for the comparison purpose , we also examine the conventional direct transmission without relay and traditional max - min relay selection . we derive closed - form intercept probability expressions of the direct transmission , traditional max - min relay selection , and proposed best relay selection schemes in rayleigh fading channels . numerical results show that the proposed best relay selection scheme strictly outperforms the traditional direct transmission and max - min relay selection schemes in terms of intercept probability . in addition , as the number of relays increases , the intercept probabilities of both traditional max - min relay selection and proposed best relay selection schemes decrease significantly , showing the advantage of exploiting multiple relays against eavesdropping attack . intercept probability , best relay selection , eavesdropping attack , physical - layer security , cooperative wireless networks . . And you have already written the first three sentences of the full article: in wireless networks , radio signals can be overheard by unauthorized users due to the broadcast nature of wireless medium , which makes the wireless communication systems vulnerable to eavesdropping attack . secret key encryption techniques have been widely used to prevent eavesdropping and ensure the confidentiality of signal transmissions . however , the cryptographic techniques rely on secret keys and introduce additional complexities due to the dynamic distribution and management of secret keys . to this end , physical - layer security is emerging as an alternative paradigm to prevent the eavesdropper attack and assure the secure communication by exploiting the physical characteristics of wireless channels .. Please generate the next two sentences of the article

the physical - layer security work was pioneered by wyner [ 1 ] and further extended in [ 2 ] , where an information - theoretic framework has been established by developing achievable secrecy rates . it has been proven in [ 2 ] that in the presence of an eavesdropper , a so - called _ secrecy capacity _ is shown as the difference between the channel capacity from source to destination ( called main link ) and that from source to eavesdropper ( called wiretap link ) . if the secrecy capacity is negative , the eavesdropper can intercept the transmission from source to destination and an intercept event occurs in this case . due to the wireless fading effect , the secrecy capacity is severely limited , which results in an increase in the intercept probability . to alleviate this problem , some existing work is proposed to improve the secrecy capacity by taking advantage of multiple antennas [ 3 ] and [ 4 ] .

Suppose that you have an abstract for a scientific paper: the inclusive reaction @xmath0 was studied at ihep accelerator with @xmath1 proton beam using svd-2 detector . two different samples of @xmath2 , statistically independent and belonging to different phase space regions were used in the analyses and a narrow baryon resonance with the mass @xmath3 was observed in both samples of the data . . And you have already written the first three sentences of the full article: in last three years the observation of a narrow baryon state named @xmath4 predicted by diakonov , petrov and polyakov@xcite has been reported by a large number of experiments in the @xmath5 or @xmath6 decay channels . several experiments , mostly at high energies , did not confirm the existence of @xmath4 . the present situation and complete list of references to positive and null results can be found in the reviews@xcite .. Please generate the next two sentences of the article

here we present a new study of the reaction @xmath7 , @xmath8 , @xmath9 , with two independent samples of @xmath2 used@xcite . a detailed description of svd-2 detector and its trigger system can be found elsewhere@xcite .

Suppose that you have an abstract for a scientific paper: hh 211 is a highly collimated jet with a chain of well - defined knots , powered by a nearby young class 0 protostar . we have used 4 epochs ( 2004 , 2008 , 2010 , and 2013 ) of submillimeter array ( sma ) archive data to study the properties of the hh 211 jet in sio ( j=8 - 7 ) . the jet shows similar reflection - symmetric wiggle structures in all epochs . the wiggle structures can all be fitted by an orbiting jet source model that includes a position shift due to proper motion of the jet , indicating that the wiggle propagates along the jet axis . thus , this suggests the wiggle is indeed due to an orbital motion of the jet source . proper motions of the knots are measured by using the peak positions of the knots in four epochs , and they are roughly the same and independent of the distance from the central source . the mean proper motion of the knots is @xmath0 per year , resulting in a transverse velocity of @xmath0 114 km s@xmath1 , about 30% lower than that measured before . knots bk2 and bk3 have a well - defined linear velocity structure , with the fast jet material upstream to the slow jet material . the gradient of the velocity structure decreases from knot bk2 to bk3 . in addition , for each knot , the gradient decreases with time , as the knot propagates away from the central source . these results are both expected if the two knots trace internal shocks produced by a small periodical variation in ejection velocity of the jet . . And you have already written the first three sentences of the full article: protostellar jets play an important role in star formation . they are believed to be launched from the innermost parts of accretion disks around protostars , carrying away excess angular momentum from the disks , allowing the disk material to fall onto the protostars ( see the review by * ? ? ? the launching mechanism of the jets is still uncertain , but can be constrained with the physical properties ( e.g. , morphology and kinematics ) of the jets . in particular , since most of the jets have knotty structures ( knots ) , studying the formation of these knots may help us to constrain how the jets are launched .. Please generate the next two sentences of the article

hh 211 is a well - studied jet consisting of a chain of well - defined knots , and thus it is a good candidate for studying the physical properties of the jet and the formation of the knots . it is nearby , located in the ic 348 complex of perseus at a distance of @xmath2280 pc @xcite .

Suppose that you have an abstract for a scientific paper: we calculate core - level spectra for pristine and doped free - standing graphene sheets . instructions for how to perform the calculations are given in detail . although pristine graphene is not metallic the core - level spectrum presents low - energy tailing which is characteristic of metallic systems . the peak shapes vary with doping level in a characteristic way . the spectra are compared to experiments and show good agreement . we compare to two different pristine samples and to one doped sample . the pristine samples are one with quasi - free - standing epitaxial graphene on sic obtained by hydrogen intercalation and one with a suspended graphene sheet . the doped sample is a gold supported graphene sheet . the gold substrate acts as an acceptor so the graphene sheet gets p - doped . . And you have already written the first three sentences of the full article: in the 1970s many - body theory flourished . a topic that attracted much attention was the many - body effects on xps ( x - ray photoelectron spectroscopy ) spectra , from deep core levels in metals@xcite . related effects were singularities that appeared near edges in absorption and emission spectra@xcite .. Please generate the next two sentences of the article

the cb ( conduction - band ) electrons can have many different effects on the xps peak from the core level . if the excitation could be considered adiabatic the screening of the core hole by the cb electrons would lead to a shift of the peak to higher kinetic energy ( lower binding energy of the core level ) . now the excitation is not adiabatic , the excitation is swift .

Suppose that you have an abstract for a scientific paper: a wormhole with a quantum throat on the basis of an approximate model of the spacetime foam is presented . an effective spinor field is introduced for the description of the spacetime foam . the consequences of such model of the wormhole is preventing a `` naked '' singularity in the reissner - nordstrm solution with @xmath0 . . And you have already written the first three sentences of the full article: by definition a wormhole ( wh ) is a bridge connecting two asymptotically flat regions . usually such construction is a classical object and should satisfy to einstein equations ( see @xcite for more detailed introduction to this field ) . the topology of the 4d wh is @xmath1 , where @xmath2 is the time , @xmath3 is the radial coordinate and @xmath4 is the cross section of the wh .. Please generate the next two sentences of the article

a space region near to the minimal cross section @xmath5 is called as a throat . the basic problem for existing of the wh is concentrated on the throat : in this region a matter violates the so - called null energy condition . in this paper

Suppose that you have an abstract for a scientific paper: interstellar dust plays decisive roles in the conversion of neutral to molecular hydrogen ( @xmath0 ) , the thermodynamical evolution of interstellar medium ( ism ) , and the modification of spectral energy distributions ( seds ) of galaxies . these important roles of dust have not been self - consistently included in previous numerical simulations of galaxy formation and evolution . we have therefore developed a new model by which one can investigate whether and how galaxy formation and evolution can be influenced by dust - related physical processes such as photo - electric heating , @xmath0 formation on dust , and stellar radiation pressure on dust in detail . a novel point of the model is that different dust species in a galaxy are represented by ` live dust ' particles ( i.e. , not test particles ) . therefore , dust particles in a galaxy not only interact gravitationally with all four components of the galaxy ( i.e. , dark matter , stars , gas , and dust ) but also are grown and destroyed through physical processes of ism . first we describe a way to include dust - related physical processes in nbody+hydrodynamical simulations of galaxy evolution in detail . then we show some preliminary results of dust - regulated galaxy evolution . the preliminary results suggest that the evolution of dust distributions driven by radiation pressure of stars is very important for the evolution of star formation rates , chemical abundances , @xmath0 fractions , and gas distributions in galaxies . [ firstpage ] ism : dust , extinction galaxies : ism galaxies : evolution infrared : galaxies stars : formation . And you have already written the first three sentences of the full article: galaxy formation is a complicated combination of many different physical processes , such as gravitational collapse ( eggen et al . 1962 ) , accretion of subgalactic clumps ( e.g. , searle & zinn 1978 ) , hierarchical merging of dark matter halos ( e.g. , white & rees 1978 ) , star formation and its feedback effects ( e.g. , larson 1974 ; dekel & silk 1986 ) , growth of bars and spiral arms ( e.g. , sellwood & carlberg 1984 ; athanassoula 2003 ) , clump dynamics ( e.g. , noguchi 1999 ) , feedback effects of active galactic nuclei ( e.g. , di matteo et al . 2005 ; springel et al . 2005 ) , hot and cold mode gaseous accretion ( e.g. , keres et al . 2005 ; dekel & birmboim 2006 ) , and environmental influences of groups and clusters ( e.g. , dressler 1980 ; bekki & couch 2011 ) . it has been a key issue for galactic and extragalactic astronomy to understand the relative importance of each of these physical processes in the formation and evolution of galaxies with different masses and hubble types residing in different environments at a give cosmic time . in order to address this key issue , many theoretical studies have tried to construct as realistic galaxy formation models as possible by using sophisticated numerical simulations .. Please generate the next two sentences of the article

one of the missing elements in these previous numerical studies of galaxy formation and evolution is interstellar dust . the efficient conversion from neutral to molecular hydrogen ( @xmath0 ) is possible on the surface of dust grains ( e.g. , gould & salpeter 1963 ; hollenbach & salpeter 1971 ) , and thermodynamical evolution of ism and interstellar chemistry are also controlled by dust ( e.g. herbst 2002 ) .

Suppose that you have an abstract for a scientific paper: our article is concerned with adaptive sampling schemes for bayesian inference that update the proposal densities using previous iterates . we introduce a copula based proposal density which is made more efficient by combining it with antithetic variable sampling . we compare the copula based proposal to an adaptive proposal density based on a multivariate mixture of normals and an adaptive random walk metropolis proposal . we also introduce a refinement of the random walk proposal which performs better for multimodal target distributions . we compare the sampling schemes using challenging but realistic models and priors applied to real data examples . the results show that for the examples studied , the adaptive independent metropolis - hastings proposals are much more efficient than the adaptive random walk proposals and that in general the copula based proposal has the best acceptance rates and lowest inefficiencies . * keywords * : antithetic variables ; clustering ; metropolis - hastings ; mixture of normals ; random effects . . And you have already written the first three sentences of the full article: bayesian inference using markov chain monte carlo simulation methods is used extensively in statistical applications . in this approach , the parameters are generated from a proposal distribution , or several such proposal distributions , with the generated proposals accepted or rejected using the metropolis - hastings method ; see for example @xcite . in adaptive sampling the parameters of the proposal distribution are tuned by using previous draws .. Please generate the next two sentences of the article

our article deals with diminishing adaptation schemes , which means that the difference between successive proposals converges to zero . in practice , this usually means that the proposals themselves eventually do not change .

Suppose that you have an abstract for a scientific paper: evolution is simultaneously driven by a number of processes such as mutation , competition and random sampling . understanding which of these processes is dominating the collective evolutionary dynamics in dependence on system properties is a fundamental aim of theoretical research . recent works quantitatively studied coevolutionary dynamics of competing species with a focus on linearly frequency - dependent interactions , derived from a game - theoretic viewpoint . however , several aspects of evolutionary dynamics , e.g. limited resources , may induce effectively nonlinear frequency dependencies . here we study the impact of nonlinear frequency dependence on evolutionary dynamics in a model class that covers linear frequency dependence as a special case . we focus on the simplest non - trivial setting of two genotypes and analyze the co - action of nonlinear frequency dependence with asymmetric mutation rates . we find that their co - action may induce novel metastable states as well as stochastic switching dynamics between them . our results reveal how the different mechanisms of mutation , selection and genetic drift contribute to the dynamics and the emergence of metastable states , suggesting that multistability is a generic feature in systems with frequency - dependent fitness . * keywords : * population dynamics ; dynamic fitness ; stochastic switching ; multistability . And you have already written the first three sentences of the full article: selection , random genetic drift and mutations are the processes underlying darwinian evolution . for a long time population geneticists have analyzed the dynamics in the simplest setting consisting of two genotypes evolving under these processes @xcite . in those studies , a genotype represents an individual s genetic makeup , completely determining all relevant properties of the individual .. Please generate the next two sentences of the article

a key concept is the so - called fitness of a genotype which represents the selection pressure for the individuals . the fitness defines the expected number of offspring an individual will produce . thus , selection acts on fitness differences preferring individuals with higher fitness over individuals with lower fitness .

Suppose that you have an abstract for a scientific paper: deciding the presence of the weak lefschetz property often is a challenging problem . continuing studies in @xcite , in this work an in - depth study is carried out in the case of artinian monomial ideals with four generators in three variables . we use a connection to lozenge tilings to describe semistability of the syzygy bundle of such an ideal , to determine its generic splitting type , and to decide the presence of the weak lefschetz property . we provide results in both characteristic zero and positive characteristic . corresponding author . ] . And you have already written the first three sentences of the full article: the _ weak lefschetz property _ for a standard graded artinian algebra @xmath0 over a field @xmath1 is a natural property . it says that there is a linear form @xmath2 such that the multiplication map @xmath3_i \rightarrow [ a]_{i+1}$ ] has maximal rank for all @xmath4 ( i.e. , it is injective or surjective ) . its presence implies , for example , restrictions on the hilbert function and graded betti numbers of the algebra ( see @xcite ) .. Please generate the next two sentences of the article

recent studies have connected the weak lefschetz property to many other questions ( see , e.g. , @xcite ) . thus , a great variety of tools from representation theory , topology , vector bundle theory , hyperplane arrangements , plane partitions , splines , differential geometry , among others has been used to decide the presence of the weak lefschetz property ( see , e.g. , @xcite ) .

Suppose that you have an abstract for a scientific paper: molecular motors power directed transport of cargoes within cells . even if a single motor is sufficient to transport a cargo , motors often cooperate in small teams . we discuss the cooperative cargo transport by several motors theoretically and explore some of its properties . in particular we emphasize how motor teams can drag cargoes through a viscous environment . . And you have already written the first three sentences of the full article: life is intimately related to movement on many different time and length scales , from molecular movements to the motility of cells and organisms . one type of movement which is ubiquitous on the molecular and cellular scale , although not specific to the organic world , is brownian motion or passive diffusion : biomolecules , vesicles , organelles , and other subcellular particles constantly undergo random movements due to thermal fluctuations.@xcite within cells , these random movements depend strongly on the size of the diffusing particles , because the effective viscosity of the cytoplasm increases with increasing particle size.@xcite while proteins typically diffuse through cytoplasm with diffusion coefficients in the range of @xmath0/s to tens of @xmath0/s and therefore explore the volume of a cell within a few minutes to several tens of minutes ( for a typical cell size of a few tens of microns ) , a 100 nm sized organelle typically has a diffusion coefficient of @xmath1/s within the cell,@xcite and would need @xmath2 days to diffuse over the length of the cell . for fast and efficient transport of large cargoes , cells therefore use active transport based on the movements of molecular motors along cytoskeletal filaments.@xcite these molecular motors convert the chemical free energy released from the hydrolysis of atp ( adenosinetriphosphate ) into directed motion and into mechanical work . they move in a directed stepwise fashion along the linear tracks provided by the cytoskeletal filaments .. Please generate the next two sentences of the article

there are three large families of cytoskeletal motors , kinesins and dyneins which move along microtubules , and myosins which move along actin filaments . the filaments have polar structures and encode the direction of motion for the motors . a specific motor steps predominantly in one direction , the forward direction of that motor .

Suppose that you have an abstract for a scientific paper: at low concentrations of methanol in ethanol - methanol binary system , the molecular interactions are seen to be uniquely complex . it is observed that the ethanol aggregates are not strictly hydrogen - bonded complexes ; dispersion forces also play a dominant role in the self - association of ethanol molecules . on the addition of small amount of methanol to ethanol , the dipolar association of ethanol is destroyed . the repulsive forces between the two moieties dominate the behavior of the binary system at lower concentration of methanol . at higher concentration of methanol @xmath0 , the strength and extent ( number ) of formation of hydrogen bonds between ethanol and methanol increases . the geometry of molecular structure at high concentration favors the fitting of component molecules with each other . intermolecular interactions in the ethanol - methanol binary system over the entire concentration range were investigated in detail using broadband dielectric spectroscopy , ftir , surface tension and refractive index studies . molecular dynamics simulations show that the hydrogen bond density is a direct function of the number of methanol molecules present , as the ethanol aggregates are not strictly hydrogen - bond constructed which is in agreement with the experimental results . . And you have already written the first three sentences of the full article: ethanol and methanol strongly self - associate due to hydrogen bonding @xcite . these primary polar liquids with c - oh group form very similar hydrogen bond acceptors and hydrogen bond donors and they exhibit extended network @xcite . on mixing , these two liquids does not form azeotropes . also , methanol does not form azeotrope with water , whereas ethanol forms an azeotrope with it .. Please generate the next two sentences of the article

although the binary system of ethanol and methanol is assumed to be ideal , their behavior at low concentrations is far from ideal @xcite . + vast experimental information is available concerning the dielectric properties , excess volume parameters , ftir spectra and refractive index of binary system of ethanol - water @xcite , methanol - water @xcite , ethanol - higher alcohols @xcite , methanol - higher alcohols @xcite , ethanol - pyrindine @xcite , methanol - pyridine @xcite , etc .

Suppose that you have an abstract for a scientific paper: we find the electric field of a point charge in ` truncated hyperbolic motion ' , in which the charge moves at a constant velocity followed by motion with a constant acceleration in its instantaneous rest frame . the same lienard - wiechert formula holds for the acceleration phase and the constant velocity phase of the charge s motion . the only modification is that the formula giving the retarded time is different for the two motions , and the acceleration is zero for the constant velocity motion . the electric field lines are continuous as the retarded time increases through the transition time between constant velocity and accelerated motion . as the transition time approaches negative infinity the electric field develops a delta function contribution that has been introduced by others as necessary to preserve gauss s law for the electric field . . And you have already written the first three sentences of the full article: a point charge with a constant acceleration @xmath0 in its instantaneous rest system follows the relativistic trajectory@xcite @xmath1 the equation relating @xmath2 and @xmath3 is a hyperbola , leading to the common designation of this motion as ` hyperbolic motion ' . the trajectory in eq . ( [ zt ] ) corresponds to a charge that comes to rest at @xmath4 at time @xmath5 after traveling an infinite distance from the infinite past where its speed @xmath61 . the electric field produced by the accelerating charge has been calculated in ref .. Please generate the next two sentences of the article

the field lines show an unusual , non - physical behavior at @xmath7 ( for observation time t=0 ) where they abruptly stop . this is because the retarded position of the charge is outside the past light cone for any @xmath8 .

Suppose that you have an abstract for a scientific paper: we have obtained a position ( at sub - arcsecond accuracy ) of the submillimeter bright source goods 850 - 5 ( also known as gn10 ) in the goods north field using the iram plateau de bure interferometer at 1.25 mm wavelengths ( mm j123633@xmath06214.1 , flux density : @xmath1 mjy ) . this source has no optical counterpart in deep acs imaging down to a limiting magnitude of i@xmath2 mag and its position is coincident with the position found in recent sub - millimeter mapping obtained at the sma @xcite . using deep vla imaging at 20 cm , we find a radio source ( @xmath3jy ) at the same position that is significantly brighter than reported in wang et al . the source is detected by spitzer in irac as well as at 24 @xmath4 m . we apply different photometric redshift estimators using measurements of the dusty , mid / far - infrared part of the sed and derive a redshift z @xmath5 . given our detection in the millimeter and radio we consider a significantly higher redshift ( e.g. , z @xmath6 * ? ? ? * ) unlikely . mm j123633@xmath06214.1 alias goods 850 - 5 nevertheless constitutes a bright representative of the high - redshift tail of the submillimeter galaxy population that may contribute a significant fraction to the ( sub)millimeter background . . And you have already written the first three sentences of the full article: research in the last decade showed that to understand the assembly and formation of massive galaxies it is critical to study submillimeter galaxies ( smgs ; see * ? ? ? * for a review ) . since their first detection ten years ago @xcite , more than three hundred dust - enshrouded high - z objects ( z @xmath72 ) have been detected by scuba and by mambo in the submillimeter and millimeter regime ( e.g. , * ? ? ? * ; * ? ? ?. Please generate the next two sentences of the article

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

Suppose that you have an abstract for a scientific paper: we consider the possibility that the gaia mission can supply data which will improve the photometric calibration of lsst . after outlining the lsst calibration process and the information that will be available from gaia , we explore two options for using gaia data . the first is to use gaia g - band photometry of selected stars , in conjunction with knowledge of the stellar parameters @xmath0 , @xmath1 , and @xmath2 , and in some cases @xmath3 , to create photometric standards in the lsst u , g , r , i , z , and y bands . we consider both main sequence ( ms ) stars and da white dwarfs ( wd ) . the accuracies of the resulting standard magnitudes from ms stars are found to be insufficient to satisfy lsst requirements using gaia data alone , but with the potential to do so when supplemented with ground based spectroscopy . the accuracies of the wd derived standards are generally adequate , but also require ground based spectroscopy . the second option is combine the lsst bandpasses into a synthetic gaia g band , which is a close approximation to the real gaia g band . this allows synthetic gaia g photometry to be directly compared with actual gaia g photometry at a level of accuracy which is useful for both verifying and improving lsst photometric calibration . . And you have already written the first three sentences of the full article: to meet its science requirements , the large synoptic survey telescope ( lsst ) @xcite places stringent requirements on the accuracy of its photometric calibration . the uniformity of photometric zeropoints across the sky is required to be 10 mmag in the grizy bands , and 20 mmag in u. additionally , color accuracy is required to be 5 mmag for colors that do not involve u , and 10 mmag for those that do . a plan for achieving these requirements is presented in @xcite .. Please generate the next two sentences of the article

achieving this plan , and verifying the accuracy of its results , relies on external data in the form of photometric standards . the goal of this paper is to explore the possibility that gaia @xcite can contribute to the external data needed for lsst photometric calibration .

Suppose that you have an abstract for a scientific paper: it is argued that a hartree - fock ( hf ) solution for coulomb interacting electrons in a simple model of the cu - o planes in la@xmath0cuo@xmath1 , is able to predict some of the most interesting properties of this material , such as its insulator character and the antiferromagnetic order . moreover , the natural appearance of pseudogaps in their paramagnetic and superconductor phases are also suggested by the discussion . these results follow after the elimination of some symmetry restrictions which are usually imposed on the single particle hf orbitals . one of them is the simplification of their spinor dependence to be of the so called @xmath2 or @xmath3 types . this constraint , seems to strongly reduce the largest space of orbitals corresponding to the rotational invariant hf formulation originally introduced by dirac . we also remove , the demand on the hf orbitals of having a bloch structure in the bravais lattice of the crystal . this procedure allows for the consideration of hf solutions having the same symmetry than the known ( symmetry breaking ) antiferromagnetic structure of the material . it turns out that the most stable hf solution of the problem corresponds to an antiferromagnetic and insulating state ( iaf ) , which magnetization rests on the experimentally determined direction . encouragingly , the evaluated magnetic moment per cell is 0.67 @xmath4 , a result that satisfactorily reproduces the experimentally measured value : 0.68 @xmath4 . another hf solution having a slightly higher energy arises and corresponds to a paramagnetic state showing a pseudogap ( ppg ) . it follows after only imposing the bloch stucture on the single particle states . finally a third paramagnetic but metallic solution ( no gap ) is also obtained by including both of the mentioned restrictions . the interesting result follows that this state only differs from the ppg pseudogap state in the form of excited empty orbitals . that is , the occupied single particle states and the hf energy.... And you have already written the first three sentences of the full article: the hubbard type of models in the theory of strongly correlated electron systems are notably successful @xcite . in particular , it is remarkable the way they reproduce the properties of mott insulators , such as metal - transitions oxides and copper - oxygen layered htc compounds @xcite . however , the efforts for developing approaches having more basic foundations had not ceased , due to the expectation that they could open the way for obtaining more exact and specific results@xcite . in this sense ,. Please generate the next two sentences of the article

methods that are grouped into the so called band theory picture are also known as first principle calculations in the literature . they are electronic structure calculations that begin with the interactions among electrons or atoms in vacuum .

Suppose that you have an abstract for a scientific paper: the high densities , long lifetimes , and narrow emission measure distributions observed in coronal loops with apex temperatures near 1mk are difficult to reconcile with physical models of the solar atmosphere . it has been proposed that the observed loops are actually composed of sub - resolution `` threads '' that have been heated impulsively and are cooling . we apply this heating scenario to nearly simultaneous observations of an evolving post - flare loop arcade observed with the euvi/_stereo _ , xrt/_hinode _ , and _ trace _ imagers and the eis spectrometer on _ hinode_. we find that it is possible to reproduce the extended loop lifetime , high electron density , and the narrow differential emission measure with a multi - thread hydrodynamic model provided that the time scale for the energy release is sufficiently short . the model , however , does not reproduce the evolution of the very high temperature emission observed with xrt . in xrt the emission appears diffuse and it may be that this discrepancy is simply due to the difficulty of isolating individual loops at these temperatures . this discrepancy may also reflect fundamental problems with our understanding of post - reconnection dynamics during the conductive cooling phase of loop evolution . . And you have already written the first three sentences of the full article: one of the principal problems in solar physics is understanding how the sun s corona is heated to very high temperatures . recent work on coronal loops indicates that they have physical properties that are difficult to reconcile with theoretical models . coronal loops with temperatures near 1mk are observed to persist longer than a characteristic cooling time , suggesting steady or quasi - steady heating ( e.g. , * ? ? ?. Please generate the next two sentences of the article

* ; * ? ? ? steady heating models , however , can not reproduce the high electron densities observed in these loops @xcite .

Suppose that you have an abstract for a scientific paper: two novel computing models based on an infinite tessellation of space - time are introduced . they consist of recursively coupled primitive building blocks . the first model is a scale - invariant generalization of cellular automata , whereas the second one utilizes self - similar petri nets . both models are capable of hypercomputations and can , for instance , `` solve '' the halting problem for turing machines . these two models are closely related , as they exhibit a step - by - step equivalence for finite computations . on the other hand , they differ greatly for computations that involve an infinite number of building blocks : the first one shows indeterministic behavior whereas the second one halts . both models are capable of challenging our understanding of computability , causality , and space - time . . And you have already written the first three sentences of the full article: every physically relevant computational model must be mapped into physical space - time and _ vice versa _ @xcite . in this line of thought , von neumann s self - reproducing cellular automata @xcite have been envisioned by zuse @xcite and other researchers @xcite as `` calculating space ; '' i.e. , as a locally connected grid of finite automata @xcite capable of universal algorithmic tasks , in which intrinsic @xcite observers are embedded @xcite . this model is conceptually discreet and noncontinuous and resolves the eleatic `` arrow '' antinomy @xcite against motion in discrete space by introducing the concept of information about the state of motion in between time steps .. Please generate the next two sentences of the article

alas , there is no direct physical evidence supporting the assumption of a tessellation of configuration space or time . given enough energy , and without the possible bound at the planck length of about @xmath0 m , physical configuration space seems to be potentially infinitely divisible .

Suppose that you have an abstract for a scientific paper: a systematic investigation of the microscopic conditions stabilizing itinerant ferromagnetism of correlated electrons in a single - band model is presented . quantitative results are obtained by quantum monte carlo simulations for a model with hubbard interaction @xmath0 and direct heisenberg exchange interaction @xmath1 within the dynamical mean - field theory . special emphasis is placed on the investigation of ( i ) the distribution of spectral weight in the density of states , ( ii ) the importance of genuine correlations , and ( iii ) the significance of the direct exchange , for the stability of itinerant ferromagnetism at finite temperatures . we find that already a moderately strong peak in the density of states near the band edge suffices to stabilize ferromagnetism at intermediate @xmath0-values in a broad range of electron densities @xmath2 . correlation effects prove to be essential : slater hartree - fock results for the transition temperature are both qualitatively and quantitatively incorrect . the nearest - neighbor heisenberg exchange does not , in general , play a decisive role . detailed results for the magnetic phase diagram as a function of @xmath0 , @xmath1 , @xmath2 , temperature @xmath3 , and the asymmetry of the density of states are presented and discussed . 2 . And you have already written the first three sentences of the full article: in contrast to conventional superconductivity and antiferromagnetism , metallic ferromagnetism is in general an intermediate or strong coupling phenomenon . since there do not exist systematic investigation schemes to solve such types of problems the stability of metallic ferromagnetism is still not sufficiently understood . this is true even within the simplest electronic correlation model , the one - band hubbard model,@xcite in spite of significant progress made recently .. Please generate the next two sentences of the article

the hubbard interaction is very unspecific , i.e. , does not depend on the lattice structure or dimension . hence the dispersion , and thereby the shape of the density of states ( dos ) , is of considerable importance for the stability of ferromagnetism .

Suppose that you have an abstract for a scientific paper: we propose a new formulation of optimal and local control algorithms which enforces the constraint of time - integrated zero - area on the control field . the fulfillment of this requirement , crucial in many physical applications , is mathematically implemented by the introduction of a lagrange multiplier aiming at penalizing the pulse area . this method allows to design a control field with an area as small as possible , while bringing the dynamical system close to the target state . we test the efficiency of this approach on two control purposes in molecular dynamics , namely , orientation and photodissociation . . And you have already written the first three sentences of the full article: in recent years , advances in quantum control have emerged through the introduction of appropriate and powerful tools coming from mathematical control theory @xcite and by the use of sophisticated experimental techniques to shape the corresponding control fields @xcite . all these efforts have lead nowadays to an unexpected and satisfactory agreement between theory and experiment . on the theoretical side , one major tool to design the control field is optimal control theory ( oct ) @xcite . over the past few years. Please generate the next two sentences of the article

, numerical iterative methods have been developed in quantum control to solve the optimization problems . basically , they can be divided into two families , the gradient ascent algorithms @xcite and the krotov @xcite or the monotonic @xcite ones .

Suppose that you have an abstract for a scientific paper: three different topics in phase - field modelling of solidification are discussed , with particular emphasis on the limitations of the currently available modelling approaches . first , thin - interface limits of two - sided phase - field models are examined , and it is shown that the antitrapping current is in general not sufficient to remove all thin - interface effects . second , orientation - field models for polycrystalline solidification are analysed , and it is shown that the standard relaxational equation of motion for the orientation field is incorrect in coherent polycrystalline matter . third , it is pointed out that the standard procedure to incorporate fluctuations into the phase - field approach can not be used in a straightforward way for a quantitative description of nucleation . . And you have already written the first three sentences of the full article: the phase - field method has become the method of choice for simulating microstructure formation during solidification . it owes its popularity mainly to its algorithmic simplicity : the cumbersome problem of tracking moving solid - liquid interfaces or grain boundaries is avoided by describing the geometry in terms of one or several phase fields . the phase fields obey simple partial differential equations that can be easily coded by standard numerical methods .. Please generate the next two sentences of the article

the foundations of the phase - field method and its application to solidification have been the subject of several recent review articles @xcite , and it seems of little use to repeat similar information here . instead , in this paper several topics are discussed where robust phase - field modelling tools are not yet available because some fundamental questions remain open . in sec .

Suppose that you have an abstract for a scientific paper: we present a comprehensive analysis of different techniques available for the spectroscopic analysis of fgk stars , and provide a recommended methodology which efficiently estimates accurate stellar atmospheric parameters for large samples of stars . our analysis includes a simultaneous equivalent width analysis of fe and fe spectral lines , and for the first time , utilises on - the - fly nlte corrections of individual fe lines . we further investigate several temperature scales , finding that estimates from balmer line measurements provide the most accurate effective temperatures at all metallicites . we apply our analysis to a large sample of both dwarf and giant stars selected from the rave survey . we then show that the difference between parameters determined by our method and that by standard 1d lte excitation - ionisation balance of fe reveals substantial systematic biases : up to @xmath0 k in effective temperature , @xmath1 dex in surface gravity , and @xmath2 dex in metallicity for stars with @xmath3 . this has large implications for the study of the stellar populations in the milky way . [ firstpage ] stars : abundances stars : late - type stars : population ii . And you have already written the first three sentences of the full article: the fundamental atmospheric ( effective temperature , surface gravity , and metallicity ) and physical ( mass and age ) parameters of stars provide the major observational foundation for chemo - dynamical studies of the milky way and other galaxies in the local group . with the dawn of large spectroscopic surveys to study individual stars , such as segue @xcite , rave @xcite , gaia - eso @xcite , and hermes @xcite , these parameters are used to infer the characteristics of different populations of stars that comprise the milky way . stellar parameters determined by spectroscopic methods are of a key importance . the only way to accurately measure metallicity is through spectroscopy , which thus underlies photometric calibrations ( e.g. , * ? ? ? * ; * ? ? ?. Please generate the next two sentences of the article

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

Suppose that you have an abstract for a scientific paper: average block entanglement in the 1d xx - model with uncorrelated random couplings is known to grow as the logarithm of the block size , in similarity to conformal systems . in this work we study random spin chains whose couplings present long range correlations , generated as gaussian fields with a power - law spectral function . ground states are always planar valence bond states , and their statistical ensembles are characterized in terms of their block entropy and their bond - length distribution , which follow power - laws . we conjecture the existence of a critical value for the spectral exponent , below which the system behavior is identical to the case of uncorrelated couplings . above that critical value , the entanglement entropy violates the area law and grows as a power law of the block size , with an exponent which increases from zero to one . similar planar bond structures are also found in statistical models of rna folding and kinetic roughening , and we trace an analogy between them and quantum valence bond states . using an inverse renormalization procedure we determine the optimal spin - chain couplings which give rise to a given planar bond structure , and study the statistical properties of the couplings whose bond structures mimic those found in rna folding . . And you have already written the first three sentences of the full article: entanglement in disordered spin chains has received much attention recently @xcite . the main reason is that , as opposed to on - site disordered systems @xcite , long - distance correlations are not destroyed in this case , but only modified in subtle ways . thus , for the 1d heisenberg and xx models with uncorrelated random couplings , the von neumann entropy of blocks of size @xmath0 is known to violate the area law and grow as @xmath1 , similarly to the conformal case @xcite .. Please generate the next two sentences of the article

the prefactor , nonetheless , is different : it is still proportional to the the central charge of the associated conformal field theory ( cft ) , but multiplied by an extra @xmath2 factor . moreover , the rnyi entropies do not satisfy the predictions of cft @xcite , because these models are not conformal invariant .

Suppose that you have an abstract for a scientific paper: we examine the scaling behavior of the entanglement entropy for the 2d quantum dimer model ( qdm ) at criticality and derive the universal finite sub - leading correction @xmath0 . we compute the value of @xmath0 without approximation working directly with the wave function of a generalized 2d qdm at the rokhsar - kivelson qcp in the continuum limit . using the replica approach , we construct the conformal boundary state corresponding to the cyclic identification of @xmath1-copies along the boundary of the observed region . we find that the universal finite term is @xmath2 where @xmath3 is the compactification radius of the bose field theory quantum lifshitz model , the effective field theory of the 2d qdm at quantum criticality . we also demonstrated that the entanglement spectrum of the critical wave function on a large but finite region is described by the characters of the underlying conformal field theory . it is shown that this is formally related to the problems of quantum brownian motion on @xmath1-dimensional lattices or equivalently a system of strings interacting with a brane containing a background electromagnetic field and can be written as an expectation value of a vertex operator . . And you have already written the first three sentences of the full article: entanglement is one of the strangest features of quantum mechanics . few would disagree that it distinguishes quantum mechanics unequivocally from classical physics . while it has played an essential role in the understanding of quantum mechanics , paradoxically it has been mostly absent from the theory of quantum phase transitions . as in the case of classical critical phenomena , the theory of a quantum phase transition is naturally based on the description of the scaling behavior of local observables .. Please generate the next two sentences of the article

indeed , much of the theory of quantum criticality is based on this extension of the framework of classical criticality allowing for the natural dynamics specified by the quantum mechanical hamiltonian of the system.@xcite in this standard description the main effect of quantum mechanics is captured by the dynamic critical exponent associated @xmath4 that governs the relative scaling of space and time and is determined by the dynamics of the quantum system . it is a major theoretical challenge is to understand the role of observables that have no classical analogue in quantum criticality .

Suppose that you have an abstract for a scientific paper: we study the central hyperplane arrangement whose hyperplanes are the vanishing loci of the weights of the first and the second fundamental representations of @xmath0 restricted to the dual fundamental weyl chamber . we obtain generating functions that count flats and faces of a given dimension . this counting is interpreted in physics as the enumeration of the phases of the coulomb and mixed coulomb - higgs branches of a five dimensional gauge theory with 8 supercharges in presence of hypermultiplets transforming in the fundamental and antisymmetric representation of a @xmath1 gauge group as described by the intriligator - morrison - seiberg superpotential . . And you have already written the first three sentences of the full article: the theory of hyperplane arrangements has deep connections with many areas of mathematics , such as combinatorics , representation theory , algebraic geometry , algebraic topology , singularity theory , and the theory of hypergeometric functions . one beautiful application of the use of hyperplane arrangements in algebraic geometry is the proof of brieskorn s conjecture by deligne @xcite in 1972 . real hyperplane arrangements serve as the motivation for the axioms that define oriented matroids .. Please generate the next two sentences of the article

see @xcite for detailed reviews of the theory of hyperplane arrangements . real hyperplane arrangements have been used recently in the physics literature to analyze the fiber structure and the network of flop transitions between different resolutions of elliptically fibered calabi - yau threefolds @xcite .

Suppose that you have an abstract for a scientific paper: we performed a search for @xmath0-@xmath1 bound state in @xmath2 @xmath3 and @xmath2 @xmath4 reactions with the wasa - at - cosy facility using a ramped beam technique . the measurement was carried out with high statistics and high acceptance . the signature of @xmath1-mesic nuclei was searched for by the measurement of the excitation functions in the vicinity of the @xmath1 production threshold for each of the considered channels . we did not observe the narrow structure which could be interpreted as a bound state . the preliminary upper limits of the total cross sections for the bound state production and decay varies from 21 nb to 36 nb for the @xmath2 @xmath3 channel , and from 5 nb to 9 nb for the @xmath2 @xmath4 channel for the bound state width ranging from 5 to 50 mev . . And you have already written the first three sentences of the full article: since haider and liu postulated a possible existence of @xmath1-mesic nuclei @xcite , many experimental groups performed measurements dedicated to search for the new kind of nuclear matter in which the @xmath1 meson is bound within a nucleus via the strong interaction . however , till now , none of the experiments have brought the clear evidence for the bound state existence . the status of the search was recently described in the following reviews @xcite . some of the experiments set the upper limits for the bound state production in several processes .. Please generate the next two sentences of the article

group estimated the upper limit of total cross section for @xmath5 process to the value of 270 nb and for @xmath5 @xmath6-@xmath7 @xmath8 to the value 70 nb . cosy - gem measurement of @xmath9 @xmath10 brought the upper limit of the total cross section for @xmath11-@xmath12 production equal to 0.46 @xmath13 0.16(stat ) @xmath13 0.06(syst ) nb @xcite .

Suppose that you have an abstract for a scientific paper: the current sample of high - redshift supernova type ia , which combines results from two teams , high-@xmath0 supernova search team and supernova cosmology project , is analyzed for the effects of weak lensing . after correcting sne magnitudes for cosmological distances , assuming recently published , homogeneous distance and error estimates , we find that brighter sne are preferentially found behind regions ( 5 - 15 arcmin radius ) which are overdense in foreground , @xmath1 galaxies . this is consistent with the interpretation that sne fluxes are magnified by foreground galaxy excess , and demagnified by foreground galaxy deficit , compared to a smooth universe case . the difference between most magnified and most demagnified sne is about 0.3 - 0.4 mag . the effect is significant at @xmath2 level . simple modeling reveals that the slope of the relation between sn magnitude and foreground galaxy density depends on the amount and distribution of matter along the line of sight to the sources , but does not depend on the specifics of the galaxy biasing scheme . [ firstpage ] gravitational lensing supernovae : general . And you have already written the first three sentences of the full article: the effects of weak gravitational lensing by the large - scale structure have been detected in several samples of high redshift qsos , intermediate redshift galaxies , and batse grbs . in the case of point sources , qsos and grbs , weak lensing manifests itself as angular ( anti-)correlations between these sources and foreground inhomogeneously distributed mass @xcite , while in the case of galaxies weak lensing is detected through its coherent shear effect ( see @xcite for a recent review ) . in principle , there is another , more direct way of detecting weak lensing , which uses fluxes of standard candles .. Please generate the next two sentences of the article

if the observed magnitudes of standard candles are corrected for cosmological distances then the effect of lensing can be seen : brighter sources will lie behind regions of mass density excess , while fainter ones will have mass deficits in their foregrounds . the best example of cosmological standard candle , supernovae type ia ( snia ) have been extensively observed with the purpose of determining the global geometry of the universe @xcite .

Suppose that you have an abstract for a scientific paper: we present the discovery of a triplet of quasars at @xmath0 . the whole system is well accommodated within @xmath1 ( i.e. , 200kpc in projected distance ) . the velocity differences among the three objects ( as measured through the broad emission line ) are @xmath2 , suggesting that the quasars belong to the same physical structure . broad band nir images of the field do not reveal evidence of galaxies or galaxy clusters that could act as a gravitational lens , ruling out the possibility that two or all the three quasars are multiple images of a single , strongly lensed source . is the second triplet of quasars known up to date . we estimate that these systems are extremely rare in terms of simple accidental superposition . the lack of strong galaxy overdensity suggests that this peculiar system is harboured in the seeds of a yet to be formed massive structure . + based on observations collected at the la silla observatory with the new technology telescope ( ntt ) of the european southern observatory ( eso ) and at the calar alto observatory with the 3.5 m telescope of the centro astrnmico hispano alemn ( caha ) . [ firstpage ] quasars : general . And you have already written the first three sentences of the full article: in the current hierarchical cosmological paradigm , galaxy mergers and interactions are a major route to galaxy formation . the strong tidal fields experienced during close encounters between gas rich systems trigger large scale nuclear inflows that can ultimately start the activity of the supermassive black holes ( smbhs ) residing in the central regions of the interacting systems ( e.g. , * ? ? ?. Please generate the next two sentences of the article

the existence of multiple , simultaneously active , smbhs represents a key observational test for this evolutionary scenario and for our understanding of the processes regulating the quasar ( qso ) activity and the co evolution of smbhs with their host galaxies . a number of studies demonstrated the connection between qsos and ultra luminous infrared galaxies that are mostly found in merging systems ( e.g. , * ? ? ? * ) and confirmed the signature of recent merger events in qso hosts ( e.g. , * ? ? ? * ) .

Suppose that you have an abstract for a scientific paper: the study on the linkage of elementary particle mass differences with pion - muon mass difference is explored further . in the present study we show this linkage to be equally true for the mass differences amongst the members of su(3 ) hadron multiplets and the hadrons belonging to multiplets having different spin and parity characteristics . this reinforces our contention that inter particle mass excitations are quantized as integral multiples of basic mass unit of 29.318 mev and thereby indicates the fundamental nature of pion - muon mass difference in the elementary particle mass distribution . . And you have already written the first three sentences of the full article: hadrons ; su(3 ) multiplets ; mass quantization . although the standard model is in excellent agreement with the rich experimental data , it leaves many questions unanswered . the observed mass spectrum of the elementary particles is one of the fundamental questions that has so far defied any reasonable explanation in the standard model@xcite@xmath0 @xcite .. Please generate the next two sentences of the article

the distribution of the elementary particle masses is quite bizzare and is spread from a fraction of ev s for neutrinos to hundreds of gev s for the top quark . apart from few patterns based on su(3 ) symmetry that led to the gell - mann okubo@xcite and coleman - glashow@xcite formulae interelating the masses of pseudoscalar mesons and octet baryons respectively , the standard model has not revealed any general order in the elementary mass spectrum . on the other hand

Suppose that you have an abstract for a scientific paper: we performed fully self - consistent calculations of @xmath0nuclear bound states within the relativistic mean - field ( rmf ) model . the g - parity motivated @xmath0meson coupling constants were adjusted to yield potentials consistent with @xmath0atom data . we confirmed large polarization effects of the nuclear core caused by the presence of the antiproton . the @xmath0 absorption in the nucleus was incorporated by means of the imaginary part of a phenomenological optical potential . the phase space reduction for the @xmath0 annihilation products was taken into account . the corresponding @xmath0 width in the medium significantly decreases , however , it still remains considerable for the @xmath0 potential consistent with experimental data . . And you have already written the first three sentences of the full article: the study of the antiproton nucleus interaction is an interesting issue which has attracted renewed interest in recent years at the prospect of future experiments at the fair facility . the @xmath0nuclear bound states and the possibility of their formation have been studied in refs .. Please generate the next two sentences of the article

these considerations are supported by a strongly attractive potential that the @xmath0 feels in the nuclear medium . within the rmf approach the real part of the @xmath0nucleus potential derived using the g - parity transformation is re@xmath1 mev deep at normal nuclear density . however , the experiments with @xmath0 atoms @xcite and @xmath0 scattering off nuclei at low energies @xcite favor shallower real part of the @xmath0nucleus potential in the range of @xmath2 mev in the nuclear interior . an important aspect of the @xmath0nucleus interaction is @xmath0 annihilation which appears to be the dominant part of the interaction .

Suppose that you have an abstract for a scientific paper: cosmic acceleration is one of the most remarkable cosmological findings of recent years . although a dark energy component has usually been invoked as the mechanism for the acceleration , a modification of friedmann equation from various higher dimensional models provides a feasible alternative . cardassian expansion is one of these scenarios , in which the universe is flat , matter ( and radiation ) dominated and accelerating but contains no dark energy component . this scenario is fully characterized by @xmath0 , the power index of the so - called cardassian term in the modified friedmann equation , and @xmath1 , the matter density parameter of the universe . in this work , we first consider the constraints on the parameter space from the turnaround redshift , @xmath2 , at which the universe switches from deceleration to acceleration . we show that , for every @xmath1 , there exist a unique @xmath3 , which makes @xmath2 reach its maximum value , @xmath4_{\rm max } = \exp\left[1/ ( 2 - 3n_{\rm peak})\right ] -1 $ ] , which is unlinearly inverse to @xmath1 . if the acceleration happans earlier than @xmath5 , suggested by type ia supernovae measurements , we have @xmath6 no matter what the power index is , and moreover , for reasonable matter density , @xmath7 , it is found @xmath8 . we next test this scenario using the sunyaev - zeldovich / x - ray data of a sample of 18 galaxy clusters with @xmath9 compiled by reese et al . ( 2002 ) . we determine @xmath0 and @xmath1 , as well as the hubble constant @xmath10 , using the @xmath11 minimization method . the best fit to the data gives @xmath12 , @xmath13 and @xmath14 ( @xmath15 is the baryonic matter density parameter ) . however the constraints from the current sz / x - ray data is weak , though a model with lower matter density is prefered . a certain range of the model parameters is also consistent with the data . . And you have already written the first three sentences of the full article: recent observations of type ia supernovae by two independent groups , the high - z supernova team ( riess et al . 1998 ) and the supernova cosmology project ( perlmutter et al . 1999 ) suggest that our universe is presently undergoing an accelerating expansion . the highest redshift supernova observed so far , sn 1997ff at @xmath16 , not only support this accelerating view , but also glimpse the earlier decelerating stage of the expansion ( riess et al .. Please generate the next two sentences of the article

it seems that determining a convincing mechanism with a solid basis in particle physics that explains the accelerating universe is emerging as one of the most important challenges in modern cosmology . it is well known that all known types of matter with positive pressure generate attractive forces and decelerate the expansion of the universe conventionally , a deceleration factor is always used to describe the status of the universe s expansion ( sandage 1988 ) . given this ,

Suppose that you have an abstract for a scientific paper: we consider the problem of identifying a linear deterministic operator from its response to a given probing signal . for a large class of linear operators , we show that stable identifiability is possible if the total support area of the operator s spreading function satisfies @xmath0 . this result holds for an arbitrary ( possibly fragmented ) support region of the spreading function , does not impose limitations on the total extent of the support region , and , most importantly , does not require the support region to be known prior to identification . furthermore , we prove that stable identifiability of _ almost all operators _ is possible if @xmath1 . this result is surprising as it says that there is no penalty for not knowing the support region of the spreading function prior to identification . algorithms that provably recover all operators with @xmath0 , and almost all operators with @xmath1 are presented . . And you have already written the first three sentences of the full article: the identification of a deterministic linear operator from the operator s response to a probing signal is an important problem in many fields of engineering . concrete examples include system identification in control theory and practice , the measurement of dispersive communication channels , and radar imaging . it is natural to ask under which conditions ( on the operator ) identification is possible , in principle , and how one would go about choosing the probing signal and extracting the operator from the corresponding output signal .. Please generate the next two sentences of the article

this paper addresses these questions by considering the ( large ) class of linear operators that can be represented as a continuous weighted superposition of time - frequency shift operators , i.e. , the operator s response to the signal @xmath2 can be written as @xmath3 where @xmath4 denotes the spreading function associated with the operator . the representation theorem ( * ? ? ? 14.3.5 ) states that the action of a large class of continuous ( and hence bounded ) linear operators can be represented as in . in the communications literature operators with input - output relation as in are referred to as linear time - varying ( ltv ) channels / systems and @xmath4 is the delay - doppler spreading function @xcite . for the special case of linear time - invariant ( lti ) systems , we have @xmath5 , so that reduces to the standard convolution relation @xmath6 the question of identifiability of lti systems is readily answered by noting that the system s response to the dirac delta function is given by the impulse response @xmath7 , which by fully characterizes the system s input - output relation .

Suppose that you have an abstract for a scientific paper: the paramagnetic phase of heavy fermion systems is investigated , using a non - perturbative local moment approach to the asymmetric periodic anderson model within the framework of dynamical mean field theory . the natural focus is on the strong coupling kondo - lattice regime wherein single - particle spectra , scattering rates , d.c . transport and optics are found to exhibit @xmath0 scaling in terms of a single underlying low - energy coherence scale @xmath1 . dynamics / transport on all relevant ( @xmath2)-scales are encompassed , from the low - energy behaviour characteristic of the lattice coherent fermi liquid , through incoherent effective single - impurity physics likewise found to arise in the universal scaling regime , to non - universal high - energy scales ; and which description in turn enables viable quantitative comparison to experiment . . And you have already written the first three sentences of the full article: lanthanide based heavy fermion ( hf ) metals constitute a major , long studied class of correlated electron materials @xcite . their behaviour is quite distinct from conventional clean metals , the basic physics being driven by strong spin - flip scattering from essentially localised @xmath3-levels , generating the large effective mass and attendant low - energy scale indicative of strong interactions . the low - temperature ( @xmath4 ) state is a lattice - coherent fermi liquid with well defined quasiparticles and coherently screened @xmath3-spins , crossing over with increasing @xmath4 to essentially incoherent screening via independent kondo scattering , before attaining characteristic clean metallic behaviour .. Please generate the next two sentences of the article

physical properties of hf are in consequence typically ` anomalous ' : e.g. the resistivity @xmath5 shows a strong non - monotonic @xmath4-dependence , while optics often exhibit rich structure from the microwave to the near infrared , and pronounced evolution on low temperature scales @xcite . theoretical treatments of hf centre on the periodic anderson model ( pam ) , in which a non - interacting conduction band hybridizes locally with a correlated @xmath3-level in each unit cell of the lattice ; or on its strong coupling limit , the kondo lattice model .

Suppose that you have an abstract for a scientific paper: we present new x - ray and far ultraviolet ( fuv ) observations of t tauri stars covering the age range 1 to 10 myr . our goals are to observationally constrain the intensity of radiation fields responsible for evaporating gas from the circumstellar disk and to assess the feasibility of current photoevaporation models , focusing on x - ray and uv radiation . we greatly increase the number of 710 myr old t tauri stars observed in the x - rays by including observations of the well populated 25 ori aggregate in the orion ob1a subassociation . with these new 710 myr objects , we confirm that x - ray emission remains constant from 110 myr . we also show , for the first time , observational evidence for the evolution of fuv radiation fields with a sample of 56 accreting and non - accreting young stars spanning 1 myr to 1 gyr . we find that the fuv emission decreases on timescales consistent with the decline of accretion in classical t tauri stars until reaching the chromospheric level in weak t tauri stars and debris disks . overall , we find that the observed strength of high energy radiation is consistent with that required by photoevaporation models to dissipate the disks in timescales of approximately 10 myr . finally , we find that the high energy fields that affect gas evolution are not similarly affecting dust evolution ; in particular , we find that disks with inner clearings , the transitional disks , have similar levels of fuv emission as full disks . . And you have already written the first three sentences of the full article: circumstellar disks , formed as a consequence of the star formation process , evolve from an initially gas rich phase to a system composed of small , planetary sized bodies , with little remaining gas . the physical processes responsible for depleting circumstellar gas from the initial minimum mass solar nebula ( mmsn ) to the low quantities remaining in debris disks , those with significant dust evolution and gas depletion , have been the focus of gas dispersal models @xcite . models for the evolution of the dust @xcite have been successfully utilized in the interpretation of a variety of infrared ( ir ) spectral shapes @xcite .. Please generate the next two sentences of the article

these models indicate that while some of the material is locked into planets and still more is accreted onto the star through viscous evolution , it is likely that photoevaporation is the most significant process playing a role in the dispersal of the gas disk . there are several contributors to photoevaporation , including x - rays or extreme ultraviolet ( euv ) photons from the central star and far ultraviolet ( fuv ) emission produced in an accretion shock at the stellar surface of classical t tauri stars , or ctts @xcite . at

Suppose that you have an abstract for a scientific paper: muons can serve as probes to precisely determine fundamental parameters of the standard model or search for ` new physics ' . the high intensity muon beams at the paul scherrer institut ( psi ) allow for precision measurements and searches for rare or forbidden processes . both types of experiments challenge the standard model in a way complementary to high energy physics . we give a short overview of recent results and ongoing experiments at psi , and of ideas for the future . muon physics , rare decay , muon lifetime , fermi constant , muon capture 14.60ef , 13.35bv , 12.15.-y , 21.45.bc , 25.30.mr , 13.15.+g . And you have already written the first three sentences of the full article: in 2008 the paul scherrer institut ( psi ) celebrated its 20@xmath0 anniversary and many years of delivering high intensity muon beams . several upgrades made the 590 mev/51 mhz ring cyclotron to be up to today the most powerful proton accelerator of its kind in the world , which delivers several 10@xmath1 muons per second to experiments . the accelerator runs now routinely with 2.0 ma proton current and was already pushed to 2.15 ma for tests . in the near future running at 2.3 ma is foreseen , and an extensive program was launched to boost the operating proton current to 2.6 ma , by 2011 , and ultimately to 3.0 ma , envisaged for 2012 @xcite . precision experiments should benefit from a correspondingly increased muon intensity .. Please generate the next two sentences of the article

charged lepton - flavor conservation has been empirically verified to a high precision , but is not a consequence of a known underlying symmetry . the decay @xmath3 is lepton - flavor violating and hence , excluding neutrino flavor mixing , forbidden within the standard model ( sm ) . neutrino masses and mixing , which is established now , introduce a contribution to this decay within the sm , however , on an unmeasurably small level of order @xmath410@xmath5 @xcite . on the other hand , there are several attractive theories beyond the sm , such as supersymmetry , which generally predict lepton - flavor - violating processes at a level within today s experimental reach

Suppose that you have an abstract for a scientific paper: we examine the unusual fe - k@xmath0 line profile in mcg @xmath16@xmath130@xmath115 observed by @xmath2 during a deep minimum in the source intensity . the intense red wing and depressed blue wing of the line have been interpreted as evidence for extreme gravitational redshifts in terms of emission from within six gravitational radii of a black hole . we find that the data do not uniquely support this interpretation and can be equally well explained by occultation of the continuum source and the putative line - emitting accretion disk , which we offer as an alternative hypothesis . two problems with previous modeling were that the equivalent width of the line during the deep minimum was required to be unusually large ( @xmath3 kev ) and the line intensity was thought to increase as the source became dim . the occultation model does not suffer from these problems . our results serve to highlight the hazards of over - interpreting observational results which have low statistical significance , to the extent that theoretical implications can become generally accepted when the data do not provide a strong case for them . . And you have already written the first three sentences of the full article: recently , iwasawa _ et al . _ ( 1996 ; hereafter i96 ) found an extremely broad iron k@xmath0 emission line with a particularly prominent red wing , extending down to @xmath4 kev , during an extended observation with the _ advanced satellite for cosmology and astrophysics _ ( _ asca _ ; see tanaka , inoue & holt 1994 ) . the peculiar line profile , measured during what has been dubbed a ` deep minimum ' ( or dm ) in the x - ray light curve , had much more emission in the red wing , and much less around the line rest energy ( @xmath5 kev ) , compared to the fe k@xmath0 profiles thus far measured for mcg @xmath16@xmath130@xmath115 and other agns ( e.g. tanaka _ et al .. Please generate the next two sentences of the article

_ 1995 , yaqoob _ et al . _ 1995 , nandra _ et al .

Suppose that you have an abstract for a scientific paper: biopolymer looping is a dynamic process that occurs ubiquitously in cells for gene regulation , protein folding , etc . in cellular environments , biopolymers are often subject to tensions which are either static , or temporally fluctuating far away from equilibrium . we study the dynamics of semiflexible polymer looping in the presence of such tensions by using brownian dynamics simulation combined with an analytical theory . we show a minute tension dramatically changes the looping time , especially for long chains . considering a dichotomically flipping noise as a simple example of the nonequilibrium tension , we find the phenomenon of resonant activation , where the looping time can be the minimum at an optimal flipping time . we discuss our results in connection with recent experiments . . And you have already written the first three sentences of the full article: the kinetics of polymer loop formation has been studied for several decades and recently has attracted renewed attention due to the particular importance in biology . the dna loop formation is a basic process that underlies genetic expression , replication , and recombination @xcite . for example , in _ e. coli _ the _ lac _ repressor ( laci)-mediated loop is crucial for the repressive regulation of _ lac _ genes .. Please generate the next two sentences of the article

the hairpin loop formation is the elementary step in protein folding @xcite and structure formation in rna folding @xcite . a cell is crowded with a multitude of subcellular structures including globular proteins and rnas @xcite , with which dna is constantly interacting . a dna fragment about to loop is often subject to temporally fluctuating forces due to its dynamic environment including the other part of the chain .

Suppose that you have an abstract for a scientific paper: this is the second part of a detailed study of the ultracompact group cg j1720 - 67.8 : in the first part we have focused the attention on the three main galaxies of the group and we have identified a number of candidate tidal dwarf galaxies ( tdgs ) . here we concentrate on these candidate tdgs . absolute photometry of these objects in @xmath0 bands confirms their relatively blue colors , as we already expected from the inspection of optical and near - infrared color maps and from the presence of emission - lines in the optical spectra . the physical conditions in such candidate tdgs are investigated through the application of photoionization models , while the optical colors are compared with grids of spectrophotometric evolutionary synthesis models from the literature . although from our data self - gravitation can not be proved for these objects , their general properties are consistent with those of other tdg candidates . additionally we present the photometry of a few `` knots '' detected in the immediate surroundings of cg j1720 - 67.8 and consider the possibility that these objects might belong to a dwarf population associated with the compact group . . And you have already written the first three sentences of the full article: an often neglected aspect of interaction - induced galaxy evolution is the possibility of formation of dwarf galaxies out of interaction debris . the formation of self - gravitating objects in tidal tails was already announced by @xcite . however some interest in these objects has started growing only in recent years .. Please generate the next two sentences of the article

numerical simulations of galaxy encounters support two possible scenarios of tidal dwarf formation . the first one predicts the formation of massive bound condensations dominated by the stellar component along tidal tails and a subsequent infall of gas from the tail into the dwarf s potential well @xcite .

Suppose that you have an abstract for a scientific paper: restart strategies are an important factor in the performance of conflict - driven davis putnam style sat solvers . selecting a good restart strategy for a problem instance can enhance the performance of a solver . inspired by recent success applying machine learning techniques to predict the runtime of sat solvers , we present a method which uses machine learning to boost solver performance through a smart selection of the restart strategy . based on easy to compute features , we train both a satisfiability classifier and runtime models . we use these models to choose between restart strategies . we present experimental results comparing this technique with the most commonly used restart strategies . our results demonstrate that machine learning is effective in improving solver performance . . And you have already written the first three sentences of the full article: restarts have been shown to boost the performance of backtracking sat solvers ( see for example @xcite,@xcite ) . a restart strategy ( @xmath0,@xmath1,@xmath2 , ... ) is a sequence of restart lengths that the solver follows in the course of its execution . the solver first performs @xmath0 steps ( in case of sat solvers a step is usually a conflict ) . if a solution is not found , the solver abandons its current partial assignment and starts over . the second time it runs for @xmath1 steps , and so on .. Please generate the next two sentences of the article

luby , sinclair and zuckerman @xcite show that for each instance there exists @xmath3 , an optimal restart length that leads to the optimal restart strategy ( @xmath3,@xmath3,@xmath3 , ... ) . in order to calculate @xmath3 , one needs to have full knowledge of the runtime distribution ( rtd ) of the instance , a condition which is rarely met in practical cases .

Suppose that you have an abstract for a scientific paper: we investigate the origin of order in the low - lying spectra of many - body systems with random two - body interactions . our study based both on analytical as well as on numerical arguments shows that except for the most @xmath0-stretched states , the ground states in the higher @xmath0-sectors are more orderly and develop larger energy gaps than the ones in the @xmath1-sector . due to different characteristic energy scales in different @xmath0-sectors the @xmath1 ground states may predominate only when all the states are taken together . pacs numbers : 05.30.fk , 21.60.-n , 24.60.lz , 21.10.re . And you have already written the first three sentences of the full article: nature of the mechanism generating order out of randomness constitutes one of the most fundamental issues of the contemporary physics . theories based on various versions of ensembles of the random matrices provide one possible theoretical frame for studying such effects . the gaussian orthogonal ensemble ( goe ) constitutes the most common reference .. Please generate the next two sentences of the article

the related concepts originate @xcite from nuclear physics and prove very useful in the area of strongly interacting fermi systems or in quantum chaos @xcite . at present they finds even broader applications in such diverse fields like the brain research @xcite , econophysics @xcite and most recently in the `` real - world '' networks or graphs @xcite .

Suppose that you have an abstract for a scientific paper: the structure of the density singularity formed in a relativistically large amplitude plasma wave close to the wavebreaking limit leads to a refraction coefficient which has a coordinate dependence with discontinuous derivatives . this results in a non - exponentially small above - barrier reflection of an electromagnetic wave interacting with the nonlinear plasma wave . . And you have already written the first three sentences of the full article: in the first part of our paper @xcite , extending an approach formulated in ref . @xcite to the relativistic limit , we have studied systematically the structure of the singularities formed in a relativistically large amplitude plasma wave close to the wavebreaking in a thermal plasma . we have shown that typically the electron density distribution in the breaking wave has a peakon " form with a discontinuous coordinate dependence of its first derivative , similar to the profiles of nonlinear water waves @xcite and that in the above breaking limit the derivative becomes infinite .. Please generate the next two sentences of the article

this results in a finite reflectivity of an electromagnetic wave interacting with nonlinear plasma waves . in particular , this is an important property because nonlinear langmuir waves play a key role in the

Suppose that you have an abstract for a scientific paper: a sample of 8 qsos with @xmath0 has been observed with vlt / uves at a typical resolution @xmath1 and s / n @xmath2 . thanks to the two - arm design of the spectrograph , a remarkable efficiency has been achieved below 400 nm and above 800 nm , which translates immediately in the possibility of obtaining new results , especially at @xmath3 . we report here new insight gained about the evolution of the number density of ly-@xmath4 lines , their column density distribution , the ionizing uv background and the cosmic baryon density . . And you have already written the first three sentences of the full article: the swift increase of the number of absorptions ( and the average opacity ) with increasing redshift is the most impressive property of the ly-@xmath4 forest . fig . [ dndz ] shows the number density evolution of the ly-@xmath4 lines @xcite in the column density interval has been chosen to allow a comparison with the hst key - programme sample at @xmath5 @xcite for which a threshold in equivalent width of 0.24 was adopted . ] the long - dashed line is the maximum - likelihood fit to the data at @xmath7 with the customary parameterization : @xmath8 .. Please generate the next two sentences of the article

the uves @xcite observations imply that the turn - off in the evolution does occur at @xmath9 , not at @xmath10 as previously suggested . -0.2 cm the evolution of the @xmath11 is governed by two main factors : the hubble expansion and the metagalactic uv background ( uvb ) . at high @xmath12 both the expansion ,

Suppose that you have an abstract for a scientific paper: we supplement ( and critically overview ) the existing extensive analysis of antiferromagnetic solution for the hubbard model with a detailed discussion of two specific features , namely ( i ) the evolution of the magnetic ( slater ) gap ( here renormalized by the electronic correlations ) into the mott - hubbard or atomic gap , and ( ii ) a rather weak renormalization of the effective mass by the correlations in the half - filled - band case , which contrasts with that for the paramagnetic case . the mass remains strongly enhanced in the non - half - filled - band case . we also stress the difference between magnetic and non - magnetic contributions to the gap . these results are discussed within the slave boson approach in the saddle - point approximation , in which there appears a _ non - linear _ staggered molecular field due to the electronic correlations that leads to the appearance of the _ magnetic gap_. they reproduce correctly the ground - state energy in the limit of strong correlations . a brief comparison with the solution in the limit of infinite dimensions and the corresponding situation in the doubly - degenerate - band case with one electron per atom is also made . pacs nos . 71.10.fd , 75.10.lp , 75.50.ee . And you have already written the first three sentences of the full article: antiferromagnetism ( af ) appears in the hubbard and related models for an arbitrary interaction strength @xmath0 provided we are close to the half - filled - band situation ( @xmath1 in the orbitally nondegenerate case ) @xcite . this is easy to understand qualitatively , since the intraatomic hubbard interaction @xmath2 is diminished by keeping apart the electrons with the opposite spins . in the strong - correlation limit @xcite this interaction leads to an antiferromagnetic kinetic exchange for an arbitrary band filling @xmath3 . at the same time , the band energy is not increased because the concomitant nesting condition for the quasiparticle states achievable for bipartite lattices only leads to the energy decrease of the occupied states , even when going beyond the hartree - fock picture . in effect , the regime of the band filling @xmath4 for which the af state is stable at given @xmath0 has been determined for variety of theoretical approaches @xcite - @xcite .. Please generate the next two sentences of the article

the reliability of the results for the half - filled case is not in question as long as they reduce to those in the hartree - fock and to the mean - field ( heisenberg ) approximations in the weak- and strong - correlation limits , respectively , as we will discuss in the following . the theoretical results are in accord with the fact that _ all _ known mott insulators with the half - filled band configuration are also antiferromagnetic insulators .

Suppose that you have an abstract for a scientific paper: we revisit the milky way satellite problem using a semi - analytical model of galaxy formation and compare the predicted luminosity function to recent result from the sdss . with cosmic photoionization , the luminosity function can be brought into broad agreement with the data between @xmath0 . this improvement over previous semi - analytical model results ( e.g. , benson et al . 2002 ) is from our adoption of improved models for galaxy merger history and galaxy merging time - scales . the very faint satellites ( @xmath1 ) formed in halos with virial temperature over @xmath2 ( mass around @xmath3 before accretion ) , but their baryon content are strongly suppressed by photoionization . we model the mass evolution of the subhalos , and compare the predicted mass - to - light ratio with the data . we find that the measured total mass inside the luminous radii of satellites are about 5% of their present total dark matter mass . . And you have already written the first three sentences of the full article: one of the most mysterious of our milky - way galaxy is the `` missing satellite problem '' that cold dark matter scenario predicts its number of satellite galaxies to be around hundred , but only dozens are observed ( e.g. moore et al . 1999 ) . a few solutions have been proposed for this contradictory . one instant question is if we are comparing the right things , i.e , how to relate the observed stellar velocity dispersion to the measured circular velocity from n - body simulation ( hayashi et al .. Please generate the next two sentences of the article

another possible solution is that photoionization suppress the gas accretion in small halos , and only halos formed before reionization can form stars . ( e.g. gnedin 2000 ) .

Suppose that you have an abstract for a scientific paper: young super star clusters and young compact massive star forming regions can provide useful information on their burst properties ( age , burst duration , sfr ) , the upper end of the imf and yield new constraints on the evolution of massive stars . through the study of their stellar populations we can in particular extend our knowledge on massive stars to extreme metallicities unavailable for such stars in the local group . here we summarise the main results from recent studies on two metallicity extremes : wolf - rayet and o star populations in very metal - poor bcd , and metal - rich compact nuclear sf regions . . And you have already written the first three sentences of the full article: two `` modes '' of star formation are observed in ( optically or uv selected ) starburst galaxies ( e.g. meurer 1995 ) : a young unresolved population responsible for emission of diffuse uv light ( meurer 1995 , also calzetti these proceedings ) , and compact stellar clusters , losely termed super star clusters ( sscs ) hereafter . sscs have been the focus of numerous recent studies related in particular to the possibility that these clusters may represent the progenitors of globular clusters ( cf . fritze von alvensleben , miller , these proceedings ) .. Please generate the next two sentences of the article

a different aspect is emphasized in the present work . we use spectroscopic observations of young star forming ( sf ) regions to determine their massive star content with the aim of providing constraints on stellar evolution models and the upper end of the imf .

Suppose that you have an abstract for a scientific paper: we present an analysis of structural features of all known galaxies with optical polar rings . we find a clear dichotomy for objects of this peculiar class . bulge - dominated s0 galaxies possess only short narrow rings , while disk - dominated objects always have wide extended polar rings . we try by gas dynamical simulations to explain such a segregation by dependence of the ring - forming process on different galaxy potentials . it is found that the total mass captured into the ring during an encounter of a host - ring system with a gas - rich spiral galaxy of comparable mass exceeds @xmath0 ( or about 10% of all gas in the donor galaxy ) , which is of the order of that found by observation . the process of gas to gather into a steady - state ring takes approximately @xmath1 years . this time is somewhat shorter for rings forming around bulge - dominated galaxies . we also present observational arguments for s0 galaxies with extended rings to be similar to late - type spirals by their photometric properties , while numerical modelling of the extended ring formation suggests that these galaxies must possess massive dark halos as well . in this case , the sizes of the modelled rings turn out large enough ( up to 30 kpc in diameter ) , and the time scale for ring formation is prolonged up to several gyrs . . And you have already written the first three sentences of the full article: recent observations ( and especially with hst ) demonstrate that mutual interactions and mergers between galaxies at early stages of evolution of the universe were probably among the main processes leading to the observed properties of galaxies ( e.g. , keel 1996 ) . even at the present epoch , at least 5 - 10% of galaxies are members of interacting systems . many other galaxies keep signs in their structure of past interactions and mergings ( for example , elliptical and s0 galaxies with inclined gaseous disks , galaxies with faint shells and ripples , galaxies with kinematically decoupled nuclei , etc . ) . polar - ring galaxies ( prgs ) , consisting of large - scale rings of stars , gas and dust orbiting around major axes of early - type galaxies , may be considered as extreme samples of possible interaction relics . indeed , in the case of prgs , the remnants of merged galaxies are not mixed in one smooth object but stay separately in a quasi - steady state for a long time .. Please generate the next two sentences of the article

prgs are very rare objects . for example , the polar ring catalogue by whitmore et al .

Suppose that you have an abstract for a scientific paper: an explanation of the puzzling alignment effect observed in cosmic ray experiments is suggested * theoretical approach to alignment phenomenon * + * i. royzen * + p.n . lebedev physical institute of russian academy of sciences 53 leninsky prospect , 117924 moscow , russia + few years ago the observation has been made [ 1 ] in cosmic ray experiments that the alignment of the main energy fluxes along a straight line in target ( transverse ) plane exceeds significantly the background level . more precisely , at superhigh energies of initial particle ( @xmath0 ) the secondary particle superfamilies detected by deep lead x - ray emulsion chamber appeared to be situated almost along straight line in target plane ( fig.1 ) . the coplanar scattering of such a type was so surprising that an attempt has been made to revise the result but instead they were confirmed with much better confidence level [ 2 ] . the analysis of the alignment effect for 74 high energy @xmath1-families induced by hadrons above and within the chamber has been carried out . their energies energies are selected to be @xmath2 ( hadron energies being restored , accounting that the energy of induced @xmath1-family is about @xmath3 of the hadron energy it is originated from ) . this analysis suggested that superfamily production happened predominantly rather low above the chamber ( at the altitude @xmath4 , since it seemed that nuclear - electromagnetic cascade development would blur alignment , if several interactions contributed ) . it confirmed a coplanar scattering and scaling - like fragmentation spectrum of energy distinguished cores . the alignment parameter @xmath5 , @xmath6 is used as the alignment criterion where @xmath7 stands for a number of centers of highest energy and @xmath8 is the angle between the two - dimensional vectors @xmath9 and @xmath10 in target plane , an event being recognized to have alignment , if @xmath11 . actually , events with @xmath12 were chosen only because of too.... And you have already written the first three sentences of the full article: in the accordance with the conventional regge - gribov approach , the one - pomeron contribution to the differential cross section of shdid can be expressed at @xmath25 in the form : @xmath26 where @xmath27 and @xmath28 are cms total interaction energy , total cross section , transverse momentum transferred , and invariant masses of final diffractively excited states respectively , @xmath29 is three - pomeron vertex and @xmath30 is the pomeron trajectory ; the parameter @xmath31 is to be chosen to single out diffraction processes from other ones [ 7 ] . since the mean slope of the pomeron trajectory is the only dimensional parameter which can be responsible for the decrease of the function @xmath29 as @xmath32 is increased , the domain where @xmath29 is expected to be nearly constant is estimated as @xmath33 where @xmath34 is an effective mean value of the derivative @xmath35 there which is reasonably evaluated to be @xmath36 . it is why this domain is expected to be remarkably large , from @xmath37 to @xmath38 or even larger ( it has been observed long ago by comparison of the elastic and single inelastic diffraction differential cross sections that @xmath39 at @xmath40 [ 7 ] , wherefrom , in particular , a rather slow @xmath41-dependence of double inelastic diffraction differential cross section at @xmath42 follows ) .. Please generate the next two sentences of the article

the double inelastic diffraction is the only type of hadron interaction which is expected to exhibit such slow transverse momentum dependence . at still larger values of squared 4-momentum transferred pomeron is expected to be dissolved to its constituents [ 6 ] that begin to interact independently , so that the `` normal '' qcd regime @xmath43 is to be approached gradually . in what follows the logarithmic dependence on @xmath41 and rather ambiguous but definitely slow decrease of @xmath44 in the right - hand side of eq.(1 ) are accounted on the average as @xmath45 .

Suppose that you have an abstract for a scientific paper: systems with the power - law quasiparticle dispersion @xmath0 exhibit non - anderson disorder - driven transitions in dimensions @xmath1 , as exemplified by weyl semimetals , 1d and 2d arrays of ultracold ions with long - range interactions , quantum kicked rotors and semiconductor models in high dimensions . we study the wavefunction structure in such systems and demonstrate that at these transitions they exhibit fractal behaviour with an infinite set of multifractal exponents . the multifractality persists even when the wavefunction localisation is forbidden by symmetry or topology and occurs as a result of elastic scattering between all momentum states in the band on length scales shorter than the mean free path . we calculate explicitly the multifractal spectra in semiconductors and weyl semimetals using one - loop and two - loop renormalisation - group approaches slightly above the marginal dimension @xmath2 . = 1 after half a century of studies , disorder - driven transitions in conducting materials still motivate extensive research efforts . anderson localisation ( al ) transition is responsible for turning a metal into an insulator when increasing the disorder strength in dimensions @xmath3 and was believed for several decades to be the only possible disorder - driven transition in non - interacting systems . al continues to fascinate researchers by its peculiar and universal properties , such as , e.g. , _ multifractality_ fractal behaviour of the wavefunctions at the transition with an infinite set of multifractal exponents@xcite . a broad class of systems with the power - law quasiparticle dispersion @xmath0 in dimensions @xmath1 displays , however , another single - particle disorder - driven transition distinct from al@xcite . this transition , unlike al , occurs only near a band edge or at a nodal point ( in a semimetal ) . it reflects in the critical behaviour of the disorder - averaged density of states ( in contrast with al ) , as well as in other physical.... And you have already written the first three sentences of the full article: here we present a two - loop renormalisation - group analysis of the multifractal properties of a disordered weyl semimetal in @xmath19 dimensions using the minimal subtraction scheme@xcite . a similar scheme has been applied recently @xcite to compute the correlation - length and dynamical exponents for a wsm to the two - loop order , following previous studies of graphene@xcite and of the equivalent gross - neveu model@xcite . also , a similar multifractality analysis has been carried out in ref .. Please generate the next two sentences of the article

@xcite for 2d ( @xmath124 ) dirac fermions on the surface of a 3d topological insulator . although there is no disorder - driven phase transition in such a 2d system , the wavefunctions display multifractal behaviour on sufficiently short length scales .

Suppose that you have an abstract for a scientific paper: we investigate magnetic reconnection in systems simultaneously containing asymmetric ( anti - parallel ) magnetic fields , asymmetric plasma densities and temperatures , and arbitrary in - plane bulk flow of plasma in the upstream regions . such configurations are common in the high - latitudes of earth s magnetopause and in tokamaks . we investigate the convection speed of the x - line , the scaling of the reconnection rate , and the condition for which the flow suppresses reconnection as a function of upstream flow speeds . we use two - dimensional particle - in - cell simulations to capture the mixing of plasma in the outflow regions better than is possible in fluid modeling . we perform simulations with asymmetric magnetic fields , simulations with asymmetric densities , and simulations with magnetopause - like parameters where both are asymmetric . for flow speeds below the predicted cutoff velocity , we find good scaling agreement with the theory presented in doss et al . , _ j. geophys . res . _ , * 120 * , 7748 ( 2015 ) . applications to planetary magnetospheres , tokamaks , and the solar wind are discussed . . And you have already written the first three sentences of the full article: magnetic reconnection is the fundamental plasma process where a change in magnetic topology facilitates the conversion of magnetic energy to plasma kinetic energy and heat . it plays a fundamental role in causing eruptions in the coronae of the sun and other stars , in the interaction between the solar wind and the magnetospheres of earth and other planets , for confinement in toroidal fusion devices , and in a large collection of astrophysical settings @xcite . there has been increased interest in the properties of reconnection in realistic systems going beyond the simplifying assumptions of the sweet - parker model @xcite . in this classical model ,. Please generate the next two sentences of the article

the magnetic fields , densities , and temperatures are equal on either side of the reconnection site , and the upstream plasmas has no bulk flow other than the inflow in the reference frame of the reconnection site . one example of going beyond this model is to allow asymmetries in the reconnecting magnetic fields , densities and temperatures on either side of the reconnecting current sheet .

Suppose that you have an abstract for a scientific paper: gesture typing is a method of text entry that is ergonomically well - suited to the form factor of touchscreen devices and allows for much faster input than tapping each letter individually . the qwerty keyboard was , however , not designed with gesture input in mind and its particular layout results in a high frequency of gesture recognition errors . in this paper , we describe a new approach to quantifying the frequency of gesture input recognition errors through the use of modeling and simulating realistically imperfect user input . we introduce new methodologies for modeling randomized gesture inputs , efficiently reconstructing words from gestures on arbitrary keyboard layouts , and using these in conjunction with a frequency weighted lexicon to perform monte carlo evaluations of keyboard error rates or any other arbitrary metric . an open source framework , dodona , is also provided that allows for these techniques to be easily employed and customized in the evaluation of a wide spectrum of possible keyboards and input methods . finally , we perform an optimization procedure over permutations of the qwerty keyboard to demonstrate the effectiveness of this approach and describe ways that future analyses can build upon these results . touchscreen keyboards , gesture input , model - based design , monte carlo simulation . And you have already written the first three sentences of the full article: the advent of smartphones and tablets has made the use of touchscreen keyboards pervasive in modern society . however , the ubiquitous qwerty keyboard was not designed with the needs of a touchscreen keyboard in mind , namely accuracy and speed . the introduction of gesture or stroke - based input methods significantly increased the speed that text could be entered on touchscreens [ @xcite ] .. Please generate the next two sentences of the article

however , this method introduces some new problems that can occur when the gesture input patterns for two words are too similar , or sometimes completely ambiguous , leading to input errors . an example gesture input error is illustrated in figure [ fig : example - swipe - collision ] .

Suppose that you have an abstract for a scientific paper: we investigate the change in the orbital period of a binary system due to dynamical tides by taking into account the evolution of a main - sequence star . three stars with masses of one , one and a half , and two solar masses are considered . a star of one solar mass at lifetimes @xmath0 yr closely corresponds to our sun . we show that a planet of one jupiter mass revolving around a star of one solar mass will fall onto the star in the main - sequence lifetime of the star due to dynamical tides if the initial orbital period of the planet is less than @xmath1 days . planets of one jupiter mass with an orbital period@xmath2 days or shorter will fall onto a star of one and a half and two solar masses in the mainsequence lifetime of the star . . And you have already written the first three sentences of the full article: tidal interactions play an important role in dynamical processes in the two - body problem in close binary systems : star star ( binary star ) or star planet . they can lead to such phenomena as synchronization and orbital circularization ( hut 1981 ; zahn 1977 ) as well as to the tidal capture ( press and teukolsky 1977 ) or disruption of an object ( star ) ( ivanov and novikov 2001 ) and the fall of the object onto the star ( rasio et al . 1996 ; penev et al . 2012 ; bolmont and mathis 2016 ) . in this paper. Please generate the next two sentences of the article

we consider the tidal interaction of two bodies : a star and a point source . the point source can be both a star ( a neutron star , a white dwarf , etc . ) and a planet .

Suppose that you have an abstract for a scientific paper: to include the quark sector , the @xmath0 ( icosahedron ) four generation lepton model is extended to a binary icosahedral symmetry @xmath1 flavor model . we find the masses of fermions , including the heavy sectors , can be accommodated . at leading order the ckm matrix is the identity and the pmns matrix , resulting from same set of vacua , corresponds to tribimaximal mixings . . And you have already written the first three sentences of the full article: the current version of the standard model ( sm ) consists of three generations of quarks and leptons . recently we proposed @xcite a four generation lepton model based on the non - abelian discrete symmetry @xmath0 ( icosahedron ) , in which the best features of the three family @xmath2 ( tetrahedral ) model survive . besides the new heavy degrees of freedom in the @xmath3 model , which satisfy the experimental constraints , we retain tribimaximal neutrino mixings , three light neutrino masses , and three sm charged lepton masses in the three light generation sector . in this paper , we will explore a generalization of our @xmath4 model to include four generations of both quarks and leptons .. Please generate the next two sentences of the article

but before launching into that discussion we must first discuss the viability of models with four generations given recent experimental developments . a fourth generation is now being constrained @xcite by precision electroweak data @xcite , by flavor symmetries @xcite , and by the higgs - like particle at 125 gev recently reported at the lhc @xcite .

Suppose that you have an abstract for a scientific paper: we present new results from our comprehensive comparative survey of two massive , intermediate redshift galaxy clusters , cl @xmath0 ( @xmath1 ) and ms @xmath2 ( @xmath3 ) . combining _ hst _ optical and _ galex _ uv imaging with keck spectroscopy of member galaxies , we identify and study several key classes of ` transition objects ' whose stellar populations or dynamical states indicate a recent or ongoing change in morphology and star formation rate . for the first time , we have been able to conclusively identify spiral galaxies in the process of transforming into s0 galaxies . this has been accomplished by locating both spirals whose star formation is being quenched as well as their eventual successors , the recently created s0s . differences between the two clusters in both the timescales and spatial location of this conversion process allow us to evaluate the relative importance of several proposed physical mechanisms that could be responsible for the transformation . combined with other diagnostics that are sensitive to either icm - driven galaxy evolution or galaxy - galaxy interactions including the residuals from the fundamental plane and the properties of ` signpost ' compact emission line galaxies we describe a self - consistent picture of galaxy evolution in clusters . we find that spiral galaxies within infalling groups have already begun a slow process of conversion into s0s primarily via gentle galaxy - galaxy interactions that act to quench star formation . the fates of spirals upon reaching the core of the cluster depend heavily on the cluster icm , with rapid conversion of all remaining spirals into s0s via ram - pressure stripping in clusters where the icm is dense . in the presence of a less - dense icm , the conversion continues at a slower pace , with galaxy - galaxy interactions continuing to play a role along with ` starvation ' by the icm . we conclude that the buildup of the local s0 population through the transformation of spiral galaxies is a heterogeneous.... And you have already written the first three sentences of the full article: it is well - known that environmental processes play a significant role in shaping the evolution of galaxies as they assemble onto clusters . with the aid of hubble space telescope ( _ hst _ ) imaging and deep optical spectroscopy , recent studies have quantified this evolution in galaxy properties , painting a picture where the fraction of early - type ( elliptical and s0 ) galaxies and the fraction of passive non - star - forming galaxies both grow with time , and at a rate that seems to depend sensitively on the local density of galaxies @xcite . yet there are a wide variety of physical processes that may be responsible for these evolutionary trends including galaxy mergers , galaxy - galaxy harassment , gas stripping by the icm , or tidal processes @xcite .. Please generate the next two sentences of the article

observationally , it has so far been impossible to fully separate the effects of the various physical processes , in large part due to the overlapping regimes of influence for each of the proposed mechanisms ( see * ? ? ? further complicating the picture , the large scale assembly states of clusters show considerable variety @xcite , such that the dominant forces acting on galaxies are likely to vary from cluster to cluster , or over the course of an individual cluster s assembly history . but

Suppose that you have an abstract for a scientific paper: in the past year , polarized deep inelastic scattering experiments at cern and slac have obtained structure function measurements off proton , neutron and deuteron targets at a level of precision never before achieved . the measurements can be used to test the bjorken and ellis - jaffe sum rules , and also to obtain information on the parton distributions in polarized nucleons . we perform a global leading - order qcd fit to the proton deep inelastic data in order to extract the spin - dependent parton distributions . by using parametric forms which are consistent with theoretical expectations at large and small @xmath0 , we find that the quark distributions are now rather well constrained . we assume that there is no significant intrinsic polarization of the strange quark sea . the data are then consistent with a modest amount of the proton s spin carried by the gluon , although the shape of the gluon distribution is not well constrained , and several qualitatively different shapes are suggested . the spin - dependent distributions we obtain can be used as input to phenomenological studies for future polarized hadron - hadron and lepton - hadron colliders . dtp/94/38 + may 1994 + 1.cm * spin - dependent parton distributions from + polarized structure function data * 1.cm t. gehrmann .2 cm _ department of physics , university of durham + durham dh1 3le , england _ + .4 cm and .4 cm w.j . stirling .2 cm _ departments of physics and mathematical sciences , university of durham + durham dh1 3le , england _ . And you have already written the first three sentences of the full article: in the last few years there has been a resurgence of interest in the spin structure of the nucleon . this was largely initiated by the measurements of the polarized structure function @xmath1 by the slac - yale @xcite and emc @xcite collaborations . in the ` naive ' parton model , @xmath2 can , like the unpolarized structure function @xmath3 , be expressed in terms of the probability distributions for finding quarks with spin parallel or antiparallel to the longitudinally polarized parent proton : @xmath4 \\ g_1(x , q^2 ) & = & \half \sum_q\ ; e_q^2\ ; [ \delta q(x ) + \delta\bar q(x ) ] \ ; , \label{naiveg1}\end{aligned}\ ] ] where @xmath5 the renewed interest in the subject was triggered by the first precision measurement of the integral of @xmath1 by the emc collaboration @xcite , @xmath6 which was significantly lower than the ` ellis - jaffe sum rule ' value of 0.18 @xcite .. Please generate the next two sentences of the article

this latter prediction is obtained by assuming that the net contribution of strange quarks to the proton spin is negligible . in the context of this model , @xmath7 and @xmath8 , the net spin carried by up and down quarks respectively , can be obtained from the @xmath9-decay rates of the octet hyperons : @xmath10 attributing the difference between the ellis - jaffe prediction and the slac - emc measurement to a non - zero strange sea polarization leads to the rather unusual result that the net spin carried by the quarks , @xmath11\ ; , \ ] ] is very small .

Suppose that you have an abstract for a scientific paper: we propose a phenomenological field theoretical approach to the chemical etching of a disordered - solid . the theory is based on a recently proposed dynamical etching model . through the introduction of a set of langevin equations for the model evolution , we are able to map the problem into a field theory related to isotropic percolation . to the best of the authors knowledge , it constitutes the first application of field theory to a problem of chemical dynamics . by using this mapping , many of the etching process critical properties are seen to be describable in terms of the percolation renormalization group fixed point . the emerging field theory has the peculiarity of being `` _ self - organized _ '' , in the sense that without any parameter fine - tuning , the system develops fractal properties up to certain scale controlled solely by the volume , @xmath0 , of the etching solution . in the limit @xmath1 the upper cut - off goes to infinity and the system becomes scale invariant . we present also a finite size scaling analysis and discuss the relation of this particular etching mechanism with gradient percolation . finally , the possibility of considering this mechanism as a new generic path to self - organized criticality is analyzed , with the characteristics of being closely related to a real physical system and therefore more directly accessible to experiments . 2 . And you have already written the first three sentences of the full article: corrosion of solids is an everyday phenomenon of evident practical importance @xcite . the recent development of theoretical tools for the study of disordered systems and fractals in the context of statistical mechanics @xcite has triggered an outburst of activity in this subject . when an etching solution is put in contact with a disordered etchable solid , the solution corrodes the weak parts of the solid surface , while the hard , stronger , parts stay uncorroded . during this process new regions of the solid , both hard and weak , are discovered and come into contact with the etching solution . as corrosion proceeds the etching power of the solution may diminish : indeed , if the etchant is consumed in the reaction , etching becomes more and more unlikely until , finally , the solution is so impoverished and the solid surface so hardened that the corrosion process is arrested . at that moment. Please generate the next two sentences of the article

all solid points in contact with the solution are too hard to be etched by the weakened etching solution . one of the most interesting aspects of this type of phenomenon is that the final solid - liquid interface has , in general , a fractal geometry , at least up to a certain scale @xcite .

Suppose that you have an abstract for a scientific paper: the ergodic hypothesis asserts that a classical mechanical system will in time visit every available configuration in phase space . thus , for an ergodic system , an ensemble average of a thermodynamic quantity can equally well be calculated by a time average over a sufficiently long period of dynamical evolution . in this paper we describe in detail how to calculate the temperature and chemical potential from the dynamics of a microcanonical classical field , using the particular example of the classical modes of a bose - condensed gas . the accurate determination of these thermodynamics quantities is essential in measuring the shift of the critical temperature of a bose gas due to non - perturbative many - body effects . . And you have already written the first three sentences of the full article: the shift in critical temperature of the homogeneous bose gas has been the subject of numerous investigations over the past fifty years . as the density of this idealized system is constant , the shift due to the mean - field is zero , and the first order shift is due to long - wavelength critical fluctuations . the first estimates were due to lee and yang @xcite , who gave two different results for the dependence on the s - wave scattering length @xmath0 . in 1999. Please generate the next two sentences of the article

_ et al.__@xcite determined that the result should be @xmath1 where @xmath2 is the particle number density , and @xmath3 is a constant of order unity . several authors have attempted to calculate this constant , and a wide range of results have been obtained , as summarised in fig . 1 of @xcite .

Suppose that you have an abstract for a scientific paper: we provide a two - sided inequality for the @xmath0optimal partition value of a measurable space according to @xmath1 nonatomic finite measures . the result extends and often improves legut ( 1988 ) since the bounds are obtained considering several partitions that maximize the weighted sum of the partition values with varying weights , instead of a single one . . And you have already written the first three sentences of the full article: let @xmath2 be a measurable space , @xmath3 , @xmath4 and let @xmath5 be nonatomic finite measures defined on the same @xmath6algebra @xmath7 . let @xmath8 stand for the set of all measurable partitions @xmath9 of @xmath10 ( @xmath11 for all @xmath12 , @xmath13 , @xmath14 for all @xmath15 ) . let @xmath16 denote the @xmath17-dimensional simplex . for this definition and the many others taken from convex analysis , we refer to @xcite .. Please generate the next two sentences of the article

a partition @xmath18 is said to be @xmath0optimal , for @xmath19 , if @xmath20 this problem has a consolidated interpretation in economics . @xmath10 is a non - homogeneous , infinitely divisible good to be distributed among @xmath1 agents with idiosyncratic preferences , represented by the measures .

Suppose that you have an abstract for a scientific paper: we present observations of the 51 ophiuchi circumstellar disk made with the keck interferometer operating in nulling mode at n - band . we model these data simultaneously with vlti - midi visibility data and a _ spitzer _ irs spectrum using a variety of optically - thin dust cloud models and an edge - on optically - thick disk model . we find that single - component optically - thin disk models and optically - thick disk models are inadequate to reproduce the observations , but an optically - thin two - component disk model can reproduce all of the major spectral and interferometric features . our preferred disk model consists of an inner disk of blackbody grains extending to @xmath0 au and an outer disk of small silicate grains extending out to @xmath1 au . our model is consistent with an inner birth " disk of continually colliding parent bodies producing an extended envelope of ejected small grains . this picture resembles the disks around vega , au microscopii , and @xmath2 pictoris , supporting the idea that 51 ophiuchius may be a @xmath2 pictoris analog . . And you have already written the first three sentences of the full article: 51 ophiuchi ( 51 oph ) , a rapidly rotating b9.5ve star located at @xmath3 pc @xcite , shows an infrared ( ir ) excess ( @xmath4% ) in its spectral energy distribution ( sed ) due to the presence of silicate grains @xcite . this system probably represents a rare nearby example of a young debris disk with gas , a planetary system just entering the late stages of formation , after the primordial gas has substantially dissipated , but before terrestrial planets have finished accreting . its nearly edge - on disk of gas and dust and its variable absorption features @xcite suggests that 51 oph may be an analog of @xmath2 pictoris ( @xmath2 pic ) .. Please generate the next two sentences of the article

several spectroscopic observations support the presence of an edge - on gaseous disk around 51 oph . double - peaked h@xmath5

Suppose that you have an abstract for a scientific paper: we evaluate the kinematic distributions in phase space of 4-parton final - state subprocesses produced by double parton scattering , and we contrast these with the final - state distributions that originate from conventional single parton scattering . our goal is to establish the distinct topologies of events that arise from these two sources and to provide a methodology for experimental determination of the relative magnitude of the double parton and single parton contributions at large hadron collider energies . we examine two cases in detail , the @xmath0 and the 4 jet final states . after full parton - level simulations , we identify a few variables that separate the two contributions remarkably well , and we suggest their use experimentally for an empirical measurement of the relative cross section . we show that the double parton contribution falls off significantly more rapidly with the transverse momentum @xmath1 of the leading jet , but , up to issues of the relative normalization , may be dominant at modest values of @xmath1 . . And you have already written the first three sentences of the full article: double parton scattering ( dps ) means that two short - distance subprocesses occur in a given hadronic interaction , with two initial partons being active from each of the incident protons in a collision at the large hadron collider ( lhc ) . the concept is shown for illustrative purposes in fig . [ fig : feyn - diag ] , and it may be contrasted with conventional single parton scattering ( sps ) in which one short - distance subprocess occurs , with one parton active from each initial hadron .. Please generate the next two sentences of the article

since the probability of single parton scattering is itself small , it is often expected that the chances are considerably suppressed for two or more short - distance interactions in a given collision . however , expectations such as these bear quantitative re - examination at the lhc where the high overall center - of - mass energy provides access to very small values of the fractional momentum @xmath2 carried by partons , a region in which parton densities grow rapidly .

Suppose that you have an abstract for a scientific paper: this paper introduces algorithms for target tracking in wireless sensor networks ( wsns ) that enable reduction of data communication cost . the objective of the considered problem is to control movement of a mobile sink which has to reach a moving target in the shortest possible time . consumption of the wsn energy resources is reduced by transferring only necessary data readings ( target positions ) to the mobile sink . simulations were performed to evaluate the proposed algorithms against existing methods . the experimental results confirm that the introduced tracking algorithms allow the data communication cost to be considerably reduced without significant increase in the amount of time that the sink needs to catch the target . . And you have already written the first three sentences of the full article: wireless sensor networks ( wsns ) can be utilized as target tracking systems that detect a moving target , localize it and report its location to the sink . so far , the wsn - based tracking systems have found various applications , such as battlefield monitoring , wildlife monitoring , intruder detection , and traffic control @xcite . this paper deals with the problem of target tracking by a mobile sink which uses information collected from sensor nodes to catch the target .. Please generate the next two sentences of the article

main objective of the considered system is to minimize time to catch , i.e. , the number of time steps in which the sink reaches the moving target . moreover , due to the limited energy resources of wsn , also the minimization of data communication cost ( hop count ) is taken into consideration .

Suppose that you have an abstract for a scientific paper: we investigate the distribution of the number of photons emitted by a single molecule undergoing a spectral diffusion process and interacting with a continuous wave laser field . the spectral diffusion is modeled based on a stochastic approach , in the spirit of the anderson - kubo line shape theory . using a generating function formalism we solve the generalized optical bloch equations , and obtain an exact analytical formula for the line shape and mandel s q parameter . the line shape exhibits well known behaviors , including motional narrowing when the stochastic modulation is fast , and power broadening . the mandel parameter , describing the line shape fluctuations , exhibits a transition from a quantum sub - poissonian behavior in the fast modulation limit , to a classical super - poissonian behavior found in the slow modulation limit . our result is applicable for weak and strong laser field , namely for arbitrary rabi frequency . we show how to choose the rabi frequency in such a way that the quantum sub - poissonian nature of the emission process becomes strongest . a lower bound on @xmath0 is found , and simple limiting behaviors are investigated . a non - trivial behavior is obtained in the intermediate modulation limit , when the time scales for spectral diffusion and the life time of the excited state , become similar . a comparison is made between our results , and previous ones derived based on the semi - classical generalized wiener khintchine formula . . And you have already written the first three sentences of the full article: physical , chemical , and biological systems are investigated in many laboratories using single molecule spectroscopy @xcite . the investigation of the distribution of the number of photons emitted from a single molecule source is the topic of extensive theoretical research e.g. @xcite and @xcite for a review . since optical properties of single molecules are usually very sensitive to dynamics and statics of their environment , and since the technique removes the many particle averaging found in conventional measurement techniques , single molecule spectroscopy reveals interesting fluctuation phenomena .. Please generate the next two sentences of the article

an important mechanism responsible for the fluctuations in the number of photons emitted from a single molecule source is spectral diffusion e.g. @xcite . in many cases the absorption frequency of the molecule will randomly change due to different types of interactions between the molecule and its environment ( e.g. @xcite and ref .

Suppose that you have an abstract for a scientific paper: in this article , we calculate the strong coupling constants of the @xmath0 , @xmath1 and @xmath2 in the framework of the light - cone qcd sum rules approach . the strong coupling constants of the meson - baryon - baryon are the fundamental parameters in the one - boson exchange model which describes the baryon - baryon interactions successfully . the numerical values are in agreement with the existing calculations in part . the electric and magnetic @xmath3 ratios deviate from the prediction of the vector meson dominance theory , the @xmath4 symmetry breaking effects are very large . + zhi - gang wang + department of physics , north china electric power university , baoding 071003 , p. r. china pacs numbers : 24.85.+p ; 12.40.vv ; 13.75.ev ; 13.75.gx . And you have already written the first three sentences of the full article: one of the successful approaches in describing the two - baryon interactions is the one - boson exchange ( or the nijmegen soft - core potential ) model @xcite . in this model , the baryon - baryon interactions are mediated by the intermediate mesons , such as the pseudoscalar octet mesons @xmath5 , @xmath6 , @xmath7 , the vector octet mesons @xmath8 , @xmath9 , @xmath10 and the scalar octet mesons @xmath11 , @xmath12 , @xmath13 , etc . the strong coupling constants of the meson - baryon - baryon are the fundamental parameters , they have been empirically determined ( or fitted ) to reproduce the data of the nucleon - nucleon , hyperon - nucleon and hyperon - hyperon interactions .. Please generate the next two sentences of the article

the strong coupling constants of the vector mesons with the octet baryons ( thereafter we will denote them by @xmath14 ) can be written in term of the @xmath0 couplings and the electric ( and magnetic ) @xmath3 ratios . the vector meson dominance theory indicates that the electric @xmath3 ratio @xmath15 be @xmath16 via the universal coupling of the @xmath8 meson to the isospin current @xcite .

Suppose that you have an abstract for a scientific paper: in this work , we extend the analysis of brown and york to find the quasilocal energy in a spherical box in the schwarzschild spacetime . quasilocal energy is the value of the hamiltonian that generates unit magnitude proper - time translations on the box orthogonal to the spatial hypersurfaces foliating the schwarzschild spacetime . we call this hamiltonian the brown - york hamiltonian . we find different classes of foliations that correspond to time - evolution by the brown - york hamiltonian . we show that although the brown - york expression for the quasilocal energy is correct , one needs to supplement their derivation with an extra set of boundary conditions on the interior end of the spatial hypersurfaces inside the hole in order to obtain it from an action principle . replacing this set of boundary conditions with another set yields the louko - whiting hamiltonian , which corresponds to time - evolution of spatial hypersurfaces in a different foliation of the schwarzschild spacetime . we argue that in the thermodynamical picture , the brown - york hamiltonian corresponds to the _ internal energy _ whereas the louko - whiting hamiltonian corresponds to the _ helmholtz free energy _ of the system . unlike what has been the usual route to black hole thermodynamics in the past , this observation immediately allows us to obtain the partition function of such a system without resorting to any kind of euclideanization of either the hamiltonian or the action . in the process , we obtain some interesting insights into the geometrical nature of black hole thermodynamics . = 10000 epsf . And you have already written the first three sentences of the full article: after more than two decades of investigations , black hole thermodynamics is still one of the most puzzling subjects in theoretical physics . one approach to studying the thermodynamical aspects of a black hole involves considering the evolution of quantum matter fields propagating on a classical ( curved ) background spacetime . this gives rise to the phenomenon of black hole radiation that was discovered by hawking in 1974 @xcite .. Please generate the next two sentences of the article

combining hawking s discovery of black hole radiance with the classical laws of black hole mechanics @xcite , leads to the laws of black hole thermodynamics . the entropy of a black hole obtained from this approach may be interpreted as resulting from averaging over the matter field degrees of freedom lying either inside the black hole @xcite or , equivalently , outside the black hole @xcite , as was first anticipated by bekenstein @xcite even before hawking s discovery .

Suppose that you have an abstract for a scientific paper: when a quantum system is monitored in continuous time , the result of the measurement is a stochastic process . when the output process is stationary , at least in the long run , the spectrum of the process can be introduced and its properties studied . a typical continual measurement for quantum optical systems is the so called homodyne detection . in this paper we show how the heisenberg uncertainty relations give rise to characteristic bounds on the possible homodyne spectra and we discuss how this is related to the typical quantum phenomenon of squeezing . . And you have already written the first three sentences of the full article: a big achievement in the 70s-80 s was to show that , inside the axiomatic formulation of quantum mechanics , based on _ positive operator valued measures _ and _ instruments_,@xcite a consistent formulation of the theory of measurements continuous in time ( _ quantum continual measurements _ ) was possible.@xcite the main applications of quantum continual measurements are in the photon detection theory in quantum optics ( _ direct , heterodyne , homodyne detection_).@xcite a very flexible and powerful formulation of continual measurement theory was based on stochastic differential equations , of classical type ( commuting noises , it calculus ) and of quantum type ( non commuting noises , hudson - parthasarathy equation).@xcite in this paper we start by giving a short presentation of continual measurement theory based on quantum sde s . we consider only the type of observables relevant for the description of homodyne detection and we make the mathematical simplification of introducing only bounded operators on the hilbert space of the quantum system and a finite number of noises . then , we introduce the spectrum of the classical stochastic process which represents the output and we study the general properties of the spectra of such classical processes by proving characteristic bounds due to the heisenberg uncertainty principle . finally , we present the case of a two - level atom , where the spectral analysis of the output can reveal the phenomenon of squeezing of the fluorescence light , a phenomenon related to the heisenberg uncertainty relations .. Please generate the next two sentences of the article

let @xmath0 be the _ system space _ , the complex separable hilbert space associated to the observed quantum system , which we call system @xmath1 . quantum stochastic calculus and

Suppose that you have an abstract for a scientific paper: employing profits data of japanese companies in 2002 and 2003 , we identify the non - gibrat s law which holds in the middle profits region . from the law of detailed balance in all regions , gibrat s law in the high region and the non - gibrat s law in the middle region , we kinematically derive the profits distribution function in the high and middle range uniformly . the distribution function accurately fits with empirical data without any fitting parameter . pacs code : 04.60.nc + keywords : econophysics ; pareto law ; gibrat law ; detailed balance . And you have already written the first three sentences of the full article: the distribution of wealth , income or company size is one of important issues not only in economics but also in econophysics @xcite . in these distributions , a cumulative number @xmath0 obeys a power - law for @xmath1 which is larger than a certain threshold @xmath2 : @xmath3 this power - law and the exponent @xmath4 are called pareto s law and pareto index , respectively @xcite . here @xmath1 is wealth , income , profits , assets , sales , the number of employees and etc .. Please generate the next two sentences of the article

the study of power - law distributions in the high range is quite significant . because a large part of the total wealth , income or profits is occupied by persons or companies in the high region , although the number of them is a few percent .

Suppose that you have an abstract for a scientific paper: correlations between the magnification or polarization of background sources , induced by gravitational lensing due to the large - scale structure , and the positions of foreground galaxies are investigated . we found that their amplitude is enhanced with respect to correlations for a single population . we analize the dependence of the correlations with the density parameter @xmath0 considering a nonlinear evolution of the matter power spectrum . the contribution of the linear evolution is negligible at scales below several arcminutes . detailed results on the dependence of the correlations on the redshift of the foreground and background populations for different cosmological models are presented . the effect reaches its maximum amplitude for foreground populations with relatively small redshifts due to the fast increase of the nonlinear matter power spectrum at recent times . cosmology : theory - gravitational lensing - large - scale structure . And you have already written the first three sentences of the full article: the gravitational deflection of photons can be used as a probe of the matter distribution along the line of sight to the sources . the latter may be at the last scattering surface ( @xmath1 ) , in the case of the cosmic microwave background ( seljak 1996 ; martnez - gonzlez et al . 1997 ; bernardeau 1997 ) , or high@xmath2 objects as qsos or galaxies ( blanford et al . 1991 ; kaiser 1992 ; kaiser & squires 1993 ; bartelmann 1995 ; villumsen 1995b ; villumsen 1996 ; bernardeau , van waerbeke & mellier 1996 ; kaiser 1996 ; jain & seljak 1996 ) .. Please generate the next two sentences of the article

information about the matter fluctuations can be obtained on different scales ranging from galaxy haloes to the large - scale structure of the universe . many of the theoretical studies on this subject have dealt with the polarization or ellipticity produced on background galaxies by the large - scale structure of the universe , and there are currently several ongoing observational projects trying to detect and quantify this effect .

Suppose that you have an abstract for a scientific paper: the equivalence of subtractively renormalized and cut - off effective field theories is demonstrated for the example of very low energy effective field theory for the nucleon - nucleon interaction . . And you have already written the first three sentences of the full article: it is widely believed that @xmath0 is the correct theory of strong interactions . on the other hand nuclear forces are studied within different potential models . it is not clear whether or not these phenomenological approaches can be justified from fundamental theory .. Please generate the next two sentences of the article

effective field theory is thought as a bridge between @xmath0 and potential models . chiral perturbation theory serves as a low - energy effective field theory inspired by qcd .

Suppose that you have an abstract for a scientific paper: we study the real - time dynamics of vortices in a large elongated bose - einstein condensate ( bec ) of sodium atoms using a stroboscopic technique . vortices are produced via the kibble - zurek mechanism in a quench across the bec transition and they slowly precess keeping their orientation perpendicular to the long axis of the trap as expected for solitonic vortices in a highly anisotropic condensate . good agreement with theoretical predictions is found for the precession period as a function of the orbit amplitude and the number of condensed atoms . in configurations with two or more vortices , we see signatures of vortex - vortex interaction in the shape and visibility of the orbits . in addition , when more than two vortices are present , their decay is faster than the thermal decay observed for one or two vortices . the possible role of vortex reconnection processes is discussed . vortex dynamics is an essential feature of quantum fluids @xcite and plays a key role in superfluid helium @xcite , superconductors @xcite , neutron stars @xcite and magnetohydrodynamics @xcite . the interaction between vortices is crucial for understanding the formation of vortex lattices in rotating superfluids and is the basic mechanism leading to quantum turbulence _ via _ vortex reconnection @xcite . vortices have been extensively investigated in atomic gases @xcite , where a variety of techniques permits the observation of single ones up to a few hundreds , interacting in a clean environment and on a spatial scale ranging from the healing length ( core size ) @xmath0 to a few tens of @xmath0 . the fact that atoms are confined by external fields of tunable geometry makes them suitable to explore the physics of reconnection and dissipation in inhomogeneous systems and in the presence of boundaries . seminal experiments were performed in rotating bose - einstein condensates ( becs ) , where the effect of rotation and long - range interaction favors vortex alignment and the formation of vortex.... And you have already written the first three sentences of the full article: during the expansion of the outcoupled atoms , optical levitation is performed with a blue - detuned @xmath67 nm laser beam to compensate for gravity and a radio frequency dressing @xcite is used to keep the out - coupled fraction confined and clearly detectable after the @xmath9 ms expansion . in particular , the rf field is such to produce a mexican - hat potential which limits the radial expansion to about @xmath68 @xmath25 m , whereas the slower axial expansion is barely perturbed . @xmath25 m . the in - situ value can be obtained considering a scale factor of @xmath69 , given by the ratio between the in - situ and expanded tf radius at @xmath46 ms ; this because the assumption of a constant @xmath70 during the expansion .. Please generate the next two sentences of the article

this gives a mean @xmath71 of @xmath72 with a standard deviation of @xmath73 . there is no statistical difference between the single - vortex distribution and the double - vortex one . ]

Suppose that you have an abstract for a scientific paper: the coupled @xmath0 , @xmath1 , @xmath2 systems are described by a @xmath3-matrix method . the parameters in this model are adjusted to get an optimal fit to @xmath4 , @xmath5 , @xmath6 and @xmath7 data in an energy range of about 100 mev each side of the @xmath8 threshold . + the coupling of photons to the @xmath9 state is extracted and also an alternative to the current @xmath10 amplitudes suggested . expansions are given for the @xmath11 and @xmath12 amplitudes in terms of the @xmath8 momentum . effects of interference of this state with background potential interactions are discussed and experimental consequences are indicated . epsf 2ex = hip 1999 21 / th + a.m. green@xmath13 , and s. wycech@xmath13 + @xmath14department of physics and helsinki institute of physics , p.o . box 9 , + fin00014 university of helsinki , finland + @xmath15soltan institute for nuclear studies , warsaw , poland pacs numbers : 13.75.-n , 25.80.-e , 25.40.v . And you have already written the first three sentences of the full article: there is an increasing interest in @xmath8-meson physics both experimentally and theoretically . on the experimental side several facilities are now able to produce sufficient @xmath8 s to enable a study to be made of their interactions with other particles . in particular , the photon machines mami@xcite and graal@xcite are supplementing the earlier hadronic machines such as saturne@xcite , celsius@xcite and cosy@xcite . the current theoretical interest stems partly from the early indications that the @xmath16 interaction is attractive and so could possibly lead to @xmath8-nucleus quasi - bound states ( e.g. refs .. Please generate the next two sentences of the article

@xcite , @xcite ) . the theoretical approaches fall into two main categories . in the one ,

Suppose that you have an abstract for a scientific paper: we describe the spectral theory of the adjacency operator of a graph which is isomorphic to a regular tree at infinity . using some combinatorics , we reduce the problem to a scattering problem for a finite rank perturbation of the adjacency operator on a regular tree . we develop this scattering theory using the classical recipes for schrdinger operators in euclidian spaces . . And you have already written the first three sentences of the full article: the aim of this paper is to describe in an explicit way the spectral theory of the adjacency operator on an infinite graph @xmath0 which , outside of a finite sub - graph @xmath1 , looks like a regular tree @xmath2 of degree @xmath3 . we mainly adapt the case of the schrdinger operators as presented in @xcite . the proofs are often simpler here and the main results are similar .. Please generate the next two sentences of the article

this paper can be read as an introduction to the scattering theory for differential operators on smooth manifolds . even if we do not find our results in the literature , there is probably nothing really new for experts in the scattering theory of schrdinger operators , except the combinatorial part in section [ sec : combi ] .

Suppose that you have an abstract for a scientific paper: fluxon transmission through impurities of different shape in a quasi - one - dimensional long josephson junction is investigated . the junction width is significantly less than its length but , at the same time , is of the order of the josephson penetration length @xmath0 or exceeds it . the retrapping current on the impurities of the point , line and rectangular shape is computed as a function of the junction width both numerically and analytically . good agreement between the analytic formulae and the numerical simulation results for the intermediate ( several @xmath0 ) junction width is observed . solitons , josephson junctions , fluxons , impurities . And you have already written the first three sentences of the full article: the dynamics of magnetic flux propagation in a long josephson junction ( ljj ) has been and continues to be a subject of strong theoretical and practical interest during the last three decades @xcite . the magnetic flux quantum in a ljj is a soliton ( also known as _ fluxon _ ) governed by the well - known sine - gordon ( sg ) equation . the convenient way to prepare a junction with the required properties is to install various inhomogeneities into it . up to now. Please generate the next two sentences of the article

the substantial theoretical work has been devoted to the study of the fluxon motion in the one - dimensional ( 1d ) ljjs with point - like @xcite and spatially extended @xcite inhomogeneities . experimental results on the fluxon scattering on impurities are reported in @xcite spatially inhomogeneous josephson systems with trapped fluxons have been discussed as prospective applications , such as fluxon - based information devices @xcite .

Suppose that you have an abstract for a scientific paper: in this communication i describe the atlas forward physics program and the detectors , lucid , zdc and alfa that have been designed to meet this experimental challenge . in addition to their primary role in the determination of atlas luminosity these detectors - in conjunction with the main atlas detector - will be used to study soft qcd and diffractive physics in the initial low luminosity phase of atlas running . finally , i will briefly describe the atlas forward proton ( afp ) project that currently represents the future of the atlas forward physics program . . And you have already written the first three sentences of the full article: the atlas central detector @xcite consists of an inner tracking detector ( @xmath0 ) , electromagnetic and hadronic calorimeters ( @xmath1 ) and the muon spectrometer ( @xmath2 ) . in addition , atlas is also equipped with the lucid @xcite , zdc @xcite and alfa @xcite detectors which partially cover the forward rapidity region . the cross - sections for elastic and diffractive production are large . at the centre - of - mass energy of 14 tev. Please generate the next two sentences of the article

the elastic cross - section is estimated to be 25 - 30 mb . the cross - section for single and double diffraction are estimated 10 - 15 mb .

Suppose that you have an abstract for a scientific paper: we present neutral hydrogen observations of the nearby edge - on spiral galaxy ngc891 which show extended extra - planar emission up to distances of 15 kpc from the plane . 3d modeling of the galaxy shows that this emission comes from halo gas rotating more slowly than the gas in the disk . we derive the rotation curves of the gas above the plane and find a gradient in rotation velocity of @xmath015 km s@xmath1 kpc@xmath1 . we also present preliminary results of a galactic fountain model applied to ngc891 . . And you have already written the first three sentences of the full article: ngc891 is one of the best known and studied nearby edge - on spiral galaxies . it is at the distance of 9.5 mpc , is classified as a sb / sbb , and it is often referred to as a galaxy very similar to the milky way @xcite . because of its very high inclination ( i@xmath288.6@xmath3 , * ? ? ? * ) it is very suitable for the study of the distribution and kinematics of the gas above the plane .. Please generate the next two sentences of the article

ngc891 has been the subject of numerous studies at different wavelengths that have led to the detection of various halo components : an extended radio halo @xcite , an extended layer of diffuse ionised gas ( dig ) ( e.g. * ? ? ? * ) and diffuse extra - planar hot gas @xcite . also `` cold '' ism components have been detected in the halo such as hi @xcite , dust @xcite and co @xcite .

Suppose that you have an abstract for a scientific paper: we study theoretically the generation of photon pairs by spontaneous four - wave mixing ( sfwm ) in photonic crystal optical fiber . we show that it is possible to engineer two - photon states with specific spectral correlation ( `` entanglement '' ) properties suitable for quantum information processing applications . we focus on the case exhibiting no spectral correlations in the two - photon component of the state , which we call factorability , and which allows heralding of single - photon pure - state wave packets without the need for spectral post filtering . we show that spontaneous four wave mixing exhibits a remarkable flexibility , permitting a wider class of two - photon states , including ultra - broadband , highly - anticorrelated states . 99 see , for example , the review by p. kok , w. j. munro , k. nemoto , t. c. ralph , j. p. dowling and g. j. milburn , `` linear optical quantum computing with photonic qubits , '' rev . mod . phys . * 79 * , 135174 ( 2007 ) . s. e. harris , m. k. oshman , and r. l. byer , `` observation of tunable optical parametric fluorescence , '' phys . rev . lett . * 18 * , 732734 ( 1967 ) . a. b. uren , c. silberhorn , k. banaszek , i. a. walmsley , r. erdmann , w. p. grice and m. g. raymer , `` generation of pure - state single - photon wavepackets by conditional preparation based on spontaneous parametric downconversion , '' laser phys . * 15 * , 146161 ( 2005 ) . m. g. raymer , j. noh , k. banaszek and i. a. walmsley , `` pure - state single - photon wave - packet generation by parmametric down - conversion in a distributed microcavity , '' phys . rev . a * 72 * , 023825 ( 2005 ) . a. b. uren , c. silberhorn , k. banaszek and i.a . walmsley , `` efficient conditional preparation of high - fidelity single photon states for fiber - optic quantum networks , '' phys . rev . lett . * 93 * , 093601 ( 2004 ) . k. banaszek , a. b. uren and i. a. walmsley , `` generation of correlated photons in controlled spatial modes.... And you have already written the first three sentences of the full article: quantum optical technologies require photon states with specific spectral properties . for example , quantum information processing using linear optics is based upon the availability of pure - state single - photon wavepackets @xcite . single - photon wavepackets can be prepared using pair generation by means of spontaneous parametric downconversion ( pdc ) , or by spontaneous four wave mixing ( sfwm ) @xcite . in both cases individual photons. Please generate the next two sentences of the article

are heralded by the detection of their siblings . the prepared photons will not normally be in pure states unless special care is taken to remove all correlations in every degree of freedom of the photon pairs , i.e. to make the two - photon state factorable@xcite .

Suppose that you have an abstract for a scientific paper: a simple example shows that losing all money is compatible with a very high sharpe ratio ( as computed after losing all money ) . however , the only way that the sharpe ratio can be high while losing money is that there is a period in which all or almost all money is lost . this note explores the best achievable sharpe and sortino ratios for investors who lose money but whose one - period returns are bounded below ( or both below and above ) by a known constant . . And you have already written the first three sentences of the full article: sharpe ratio @xcite has become a `` gold standard '' for measuring performance of hedge funds and other institutional investors ( this note uses the generic term `` portfolio '' ) . it is sometimes argued that it is applicable only to i.i.d . gaussian returns , but we will follow a common practice of ignoring such assumptions . for simplicity. Please generate the next two sentences of the article

we assume that the benchmark return ( such as the risk - free rate ) is zero . the ( ex post ) _ sharpe ratio _ of a sequence of returns @xmath0 is defined as @xmath1 , where @xmath2 ( none of our results will be affected if we replace , assuming @xmath3 , @xmath4 by @xmath5 , as in @xcite , ( 6 ) . )

Suppose that you have an abstract for a scientific paper: the hypercat database is developed at _ observatoire de lyon _ and is distributed on the web(www - obs.univ - lyon1.fr / hypercat ) through different mirrors in europe . the goal of hypercat is to gather data necessary for studying the evolution of galaxies ( dynamics and stellar contains ) and particularly for providing a @xmath0 reference for these studies . . And you have already written the first three sentences of the full article: hypercat maintains catalogues of data collected in the literature or at the telescope , concerning the photometry , kinematics and spectrophotometry of galaxies . some catalogues contain `` global '' properties as total magnitude and other spatially resolved data . they give basic data to study the scaling relations of galaxies , as for instance the fundamental plane , and contain all the information needed to make the necessary corrections and normalizations in order to compare measurements of galaxies at different redshifts .. Please generate the next two sentences of the article

the catalogues of global properties are : * _ the catalogue of central velocity dispersions _ ( for galaxies and globular clusters ) has been presented in a preliminary form in prugniel & simien 1996 .

Suppose that you have an abstract for a scientific paper: we investigate the combined effects of distributed delay and the balance between excitatory and inhibitory nodes on the stability of synchronous oscillations in a network of coupled stuart landau oscillators . to this end a symmetric network model is proposed for which the stability can be investigated analytically . it is found that beyond a critical inhibition ratio synchronization tends to be unstable . however , increasing distributional widths can counteract this trend leading to multiple resynchronization transitions at relatively high inhibition ratios . the extended applicability of the results is confirmed by numerical studies on asymmetrically perturbed network topologies . all investigations are performed on two distribution types , a uniform distribution and a gamma distribution . . And you have already written the first three sentences of the full article: the balance between excitatory and inhibitory elements is of great relevance for processes of self - organization in various neurological structures @xcite . synchronization is one prominent phenomenon that is critically influenced by the balance of excitation and inhibition @xcite and is itself an important mechanism involved in processes such diverse as learning and visual perception on the one hand @xcite and the occurrence of parkinson s disease and epilepsy on the other hand @xcite . exploring the preconditions for synchronization on a theoretical level can be effectively performed within the framework of complex dynamical networks a field that has gained much attention during the last decades @xcite .. Please generate the next two sentences of the article

the influence of a particular network architecture can be rich and is widely studied . however , the interaction between the elements of the network can be modeled not only by the strength of the connecting links , but in addition , time - delayed coupling can be incorporated to take into account finite signal transmission times .

Suppose that you have an abstract for a scientific paper: this paper presents some statistical correlations of 72 northern spiral galaxies . the results show that early - type spirals that are brighter , and thicker , and the axis ratios ( @xmath0 ) of the disk tend to be smaller along the hubble sequence . we also find that @xmath0 correlates strongly with the galaxy s color , and early - type spirals have larger values of @xmath0 . the inclinations obtained by fitting the pattern of a spiral structure with a logarithmic spiral form are nearly the same as those obtained by using the formulas of aaronson et al . ( 1980 ) . finally , the mean measured pitch angles for the different hubble sequences in the third catalogue of bright galaxies by de vaucouleurs et al . ( 1991 ) are derived . . And you have already written the first three sentences of the full article: the inclination of a spiral galaxy ( i.e. , the angle between the galactic plane and the tangent plane of the celestial sphere ) is not only an important parameter , but also difficult to determine . a spiral galaxy consists of a thin disk , a bulge and spiral arms that are thought to be situated in the disk . if we assume that the thickness of the spiral plane is rather negligible in comparision to its extension , and that when a spiral galaxy is inclined moderately to the plane of sky , the thickness of the nucleus can be omitted , the inclination @xmath1 can be obtained by : @xmath2 where @xmath3 and @xmath4 are the apparent major and minor isophotal diameters respectively . when a spiral galaxy is seen edge - on , it is not possible to consider the thickness of the nuclear part as negligible. Please generate the next two sentences of the article

thus , eq . ( 1 ) can not be used to calculate the inclination . the reason for this is that the apparent minor isophotal - diameter consists of two parts .

Suppose that you have an abstract for a scientific paper: we study the fluctuations of the light emitted by two identical incoherent point sources in a disordered environment . the intensity - intensity correlation function and the speckle contrast , obtained after proper temporal and configurational averaging , encode the relative distance between the two sources . this suggests the intriguing possibility that intensity measurements at only one point in a speckle pattern produced by two incoherent sources can provide information about the relative distance between the sources , with a precision that is not limited by diffraction . the theory also suggests an alternative approach to green s function retrieval technique , where the correlations of the isotropic ambient noise detected by two receivers are replaced by a measurement at a single point of the noise due to two fluctuating incoherent sources . . And you have already written the first three sentences of the full article: pushing the resolution limits of light microscopy , and understanding optical phenomena on scales below the diffraction limit , has been the driving force of what is known today as nano - optics @xcite . to overcome this limit , most of the early work was focused on near - field optical microscopy and related techniques @xcite . however , in recent years , new concepts in fluorescence microscopy have pushed the resolution of far - field imaging down to the nanometer range @xcite . most of these methods @xcite rely on the accurate localization of individual fluorescent markers , that are isolated from one another on the basis of one or more distinguishing optical characteristics , or by selective or random activation of a bright and a dark state @xcite .. Please generate the next two sentences of the article

determining the location of an isolated fluorescent marker is only limited by photon noise , and not by the diffraction barrier . a key issue affecting these subwavelength imaging methods is the optical transparency of the media surrounding the light emitters .

Suppose that you have an abstract for a scientific paper: the efficiency of a thermal engine working in linear response regime in a multi - terminal configuration is discussed . for the generic three - terminal case , we provide a general definition of local and non - local transport coefficients : electrical and thermal conductances , and thermoelectric powers . within the onsager formalism , we derive analytical expressions for the efficiency at maximum power , which can be written in terms of generalized figures of merit . furthermore , using two examples , we investigate numerically how a third terminal could improve the performance of a quantum system , and under which conditions non - local thermoelectric effects can be observed . . And you have already written the first three sentences of the full article: thermoelectricity has recently received enormous attention due to the constant demand for new and powerful ways of energy conversion . increasing the efficiency of thermoelectric materials , in the whole range spanning from macro- to nano - scales , is one of the main challenges , of great importance for several different technological applications @xcite . progress in understanding thermoelectricity at the nanoscale will have important applications for ultra - sensitive all - electric heat and energy transport detectors , energy transduction , heat rectifiers and refrigerators , just to mention a few examples .. Please generate the next two sentences of the article

the search for optimisation of nano - scale heat engines and refrigerators has hence stimulated a large body of activity , recently reviewed by benenti _ et al . _

Suppose that you have an abstract for a scientific paper: we present a detailed analysis of the structure and resolved stellar populations of simulated merger remnants , and compare them to observations of compact quiescent galaxies at @xmath0 . we find that major merging is a viable mechanism to produce systems of @xmath1 and @xmath2 kpc size , provided the gas fraction at the time of final coalescence is high ( @xmath3% ) , and provided that the progenitors are compact star - forming galaxies , as expected at high redshift . their integrated spectral energy distributions and velocity dispersions are in good agreement with the observations , and their position in the @xmath4 diagram traces the upper envelope of the distribution of lower redshift early - type galaxies . the simulated merger remnants show time- and sightline - dependent @xmath5 ratio gradients that result from a superposition of radially dependent stellar age , stellar metallicity , and extinction . the median ratio of effective radius in rest - frame @xmath6-band light to that in mass surface density is @xmath7 during the quiescent remnant phase . this is typically expressed by a negative color gradient ( i.e. , red core ) , which we expect to correlate with the integrated color of the system . finally , the simulations differ from the observations in their surface brightness profile shape . the simulated remnants are typically best fit by high ( @xmath8 ) sersic indices , whereas observed quiescent galaxies at @xmath0 tend to be less cuspy ( @xmath9 ) . limiting early star formation in the progenitors may be required to prevent the simulated merger remnants from having extended wings . . And you have already written the first three sentences of the full article: recent surveys of the high - redshift universe have identified a substantial population of massive quiescent galaxies , already in place at @xmath10 ( e.g. , labb et al . 2005 ; daddi et al . 2005 ; van dokkum et al . 2006 ; kriek et al .. Please generate the next two sentences of the article

studies of their structural parameters have convincingly ruled out simple monolithic collapse models , in which little to no structural evolution is expected . instead , observational studies find galaxies , and especially quiescent galaxies , to grow significantly in size as time progresses ( e.g. , trujillo et al .

Suppose that you have an abstract for a scientific paper: thermodynamic stability of black holes , described by the rnyi formula as equilibrium compatible entropy function , is investigated . it is shown that within this approach , asymptotically flat , schwarzschild black holes can be in stable equilibrium with thermal radiation at a fixed temperature . this implies that the canonical ensemble exists just like in anti - de sitter space , and nonextensive effects can stabilize the black holes in a very similar way as it is done by the gravitational potential of an anti - de sitter space . furthermore , it is also shown that a hawking page - like black hole phase transition occurs at a critical temperature which depends on the @xmath0-parameter of the rnyi formula . non - extensive entropy , black hole thermodynamics , stability . And you have already written the first three sentences of the full article: the aim of this letter is to investigate the thermodynamic stability problem of a schwarzschild black hole based on a recent approach @xcite , where the equilibrium compatible entropy function of the black hole is considered to be the rnyi one @xcite . the nonextensive nature of the bekenstein - hawking entropy of black hole event horizons has been noticed @xcite very early on after the thermodynamic theory of black holes had been formulated @xcite , and the corresponding thermodynamic stability problem has also been investigated many times with various approaches . the standard stability analysis of extensive systems however ( with the criteria that the _ hessian _ of the entropy function has no positive eigenvalues ) , is not applicable for black holes , as it strongly depends on the _ additive _ property of the entropy function , which condition clearly fails to hold in this case .. Please generate the next two sentences of the article

the standard thermodynamic functions of a schwarzschild black hole are given by @xmath1 and @xmath2 where @xmath3 is the bekenstein - hawking entropy , @xmath4 is the hawking temperature and @xmath5 is the corresponding heat capacity of the black hole . in the classical approach ( concluding from a _ hessian _ analysis ) , schwarzschild black holes appear to be thermodynamically unstable in the canonical treatment , since the heat capacity of the hole is always negative . on the other hand , this approach is clearly not reliable , as the bekenstein - hawking entropy is not additive , and the corresponding hawking temperature is also not compatible with thermal equilibrium requirements @xcite . for a better understanding on the problem , one needs to consider the consequences of nonadditive thermodynamic effects as well . to circumvent this issue , kaburaki _

Suppose that you have an abstract for a scientific paper: tes - based bolometer and microcalorimeter arrays with thousands of pixels are under development for several space - based and ground - based applications . a linear detector response and low levels of cross talk facilitate the calibration of the instruments . in an effort to improve the properties of tes - based detectors , fixing the tes resistance in a resistance - locked loop ( rll ) under optical loading has recently been proposed . earlier theoretical work on this mode of operation has shown that the detector speed , linearity and dynamic range should improve with respect to voltage biased operation . this paper presents an experimental demonstration of multiplexed readout in this mode of operation in a tes - based detector array with noise equivalent power values ( nep ) of @xmath0w/@xmath1 . the measured noise and dynamic properties of the detector in the rll will be compared with the earlier modelling work . furthermore , the practical implementation routes for future fdm systems for the readout of bolometer and microcalorimeter arrays will be discussed . . And you have already written the first three sentences of the full article: imaging detector arrays based on transition edge sensors ( tes ) are a maturing technology for a range of both earth and space - base applications , such as infrared astronomy , x - ray astronomy , and material analysis . squid - based multiplexed readout is needed to obtain a detector noise limited readout chain . multiplexing in this context implies that multiple tes signals which overlap in time and phase space are made mathematically independent so that they can be transported through a shared readout chain without losing information , by multiplying each tes signal with an independent carrier and subsequently adding these modulated tes signals .. Please generate the next two sentences of the article

the various multiplexing variants which are being developed can be ordered based on their modulating element . we distinguish the variants in which the squid is the multiplying element which mounts the signal on a carrier , and the variant in which the tes mounts the signal on the carrier ( fdm ) .

Suppose that you have an abstract for a scientific paper: i derive precise results for absorbing - state phase transitions using exact ( numerically determined ) quasistationary probability distributions for small systems . analysis of the contact process on rings of 23 or fewer sites yields critical properties ( control parameter , order - parameter ratios , and critical exponents @xmath0 and @xmath1 ) with an accuracy of better than 0.1% ; for the exponent @xmath2 the accuracy is about 0.5% . good results are also obtained for the pair contact process . . And you have already written the first three sentences of the full article: stochastic processes with an absorbing state arise frequently in statistical physics @xcite . in systems with spatial structure , phase transitions to an absorbing state , as exemplified by the contact process @xcite , are widely studied in connection with self - organized criticality @xcite , the transition to turbulence @xcite , and issues of universality in nonequilibrium critical phenomena @xcite . interest in such transitions should continue to grow in the wake of experimental confirmation in a liquid crystal system @xcite . this letter presents a new theoretical approach to absorbing - state phase transitions via analysis of exact ( numerical ) quasistationary ( qs ) probability distributions .. Please generate the next two sentences of the article

the quasistationary probability distribution ( qsd ) provides a wealth of information about systems exhibiting an absorbing - state phase transition @xcite . ( since the only true stationary state for a finite system is the absorbing one , stationary - state " simulations in fact probe qs properties , that is , conditioned on survival . ) in particular , the order parameter and its moments , static correlation functions , and the qs lifetime are all accessible from the qsd . until now , qs properties of systems with spatial structure have been determined only via simulation @xcite ; here i develop an effective scheme for determining the qsd on rings of @xmath3 sites .

Suppose that you have an abstract for a scientific paper: we propose a simulation model to study the properties of directed percolation in two - dimensional ( 2d ) anisotropic random media . the degree of anisotropy in the model is given by the ratio @xmath0 between the axes of a semi - ellipse enclosing the bonds that promote percolation in one direction . at percolation , this simple model shows that the average number of bonds per site in 2d is an invariant equal to 2.8 independently of @xmath0 . this result suggests that sinai s theorem proposed originally for isotropic percolation is also valid for anisotropic directed percolation problems . the new invariant also yields a constant fractal dimension @xmath1 for all @xmath0 , which is the same value found in isotropic directed percolation ( _ i.e. _ , @xmath2 ) . . And you have already written the first three sentences of the full article: critical phenomena @xcite in anisotropic systems without equivalent nearest neighbors constitute an interesting research topic @xcite . a universal formula for percolation thresholds , that involves the dimension of the anisotropic lattice and an arithmetic average of the coordination number for different anisotropic lattices , has been recently postulated in ref.@xcite . the extension of these studies to more complex problems , such as directed percolation ( dp ) , and more complex systems , such as anisotropic random systems , is yet to be addressed . in this context , random systems are good candidates to model anisotropy since they do not have equivalent nearest neighbors nor equivalent sites at all lengths . in this work. Please generate the next two sentences of the article

we propose a simple simulation model to study the properties of dp in two - dimensional ( 2d ) anisotropic random media . the degree of anisotropy is computed by means of the ratio @xmath3 between the axes of a semi - ellipse enclosing the bonds that promote percolation in one direction , such that @xmath4 ( see fig.1 ) . as a function of the order parameter @xmath0 and at the percolation threshold , we measure the correlation length exponent @xmath5 and the fractal dimension @xmath6 of the largest percolating clusters ( in systems of up to 51200 random sites ) . in the present model ,

Suppose that you have an abstract for a scientific paper: structural defects in a crystal are responsible for the `` two length - scale '' behavior , in which a sharp central peak is superimposed over a broad peak in critical diffuse x - ray scattering . we have previously measured the scaling behavior of the central peak by scattering from a near - surface region of a v@xmath0h crystal , which has a first - order transition in the bulk . as the temperature is lowered toward the critical temperature , a crossover in critical behavior is seen , with the temperature range nearest to the critical point being characterized by mean field exponents . near the transition , a small two - phase coexistence region is observed . the values of transition and crossover temperatures decay with depth . an explanation of these experimental results is here proposed by means of a theory in which edge dislocations in the near - surface region occur in walls oriented in the two directions normal to the surface . the strain caused by the dislocation lines causes the ordering in the crystal to occur as growth of roughly cylindrically shaped regions . after the regions have reached a certain size , the crossover in the critical behavior occurs , and mean field behavior prevails . at a still lower temperature , the rest of the material between the cylindrical regions orders via a weak first - order transition . . And you have already written the first three sentences of the full article: since defects exist in any real system , the understanding of their influence on ordering and structural phase transitions is important . a signature of the presence of defects in a crystal near a phase transition is the so - called `` two length - scale '' behavior , in which , in the critical diffuse scattering ( cds ) of x - rays or neutrons , a narrow `` central peak '' is found on top of a broad peak @xcite . previous theoretical studies of this behavior have established that one cause of this is the presence of dislocation lines @xcite .. Please generate the next two sentences of the article

these theories argue that the strain field associated with a dislocation line results in the growth of a roughly cylindrical ordered region near the dislocation line itself . such regions order at a temperature higher than the defect - free crystal . accordingly , while the order occurs in the cylindrical regions , the broad peak in the cds is due to thermal fluctuations in regions of the material which are relatively unaffected by the strain field , while the narrow central peak is due to the fluctuations in regions where the enhanced ordering occurs .

Suppose that you have an abstract for a scientific paper: we derive the time - evolution equation that describes the brownian motion of labeled individual tracer particles in a simple model atomic liquid ( i.e. , a system of @xmath0 particles whose motion is governed by newton s second law , and interacting through spherically symmetric pairwise potentials ) . we base our derivation on the generalized langevin equation formalism , and find that the resulting time evolution equation is formally identical to the generalized langevin equation that describes the brownian motion of individual tracer particles in a colloidal suspension in the absence of hydrodynamic interactions . this formal dynamic equivalence implies the long - time indistinguishability of some dynamic properties of both systems , such as their mean squared displacement , upon a well - defined time scaling . this prediction is tested here by comparing the results of molecular and brownian dynamics simulations performed on the hard sphere system . . And you have already written the first three sentences of the full article: it is well known that under some circumstances the phenomenology of atomic liquids finds an almost perfect correspondence in the phenomenology of colloidal fluids @xcite . this seems to be particularly true regarding the rather complex dynamic behavior of these systems as they approach the glass transition @xcite . although it is clear that this analogy has some fundamental limitations ( such as the presence of many - body hydrodynamic interactions in colloidal systems ) , one can be confident , for example , that the phase behavior of colloidal and atomic systems with identical interaction potentials will , of course , be the same . thus , if one approaches this problem with a dynamic simulation technique , one is confident that the equilibrium phase diagram of a specific system ( say a lennard - jones liquid ) will be independent of the simulation technique employed in its determination ( either molecular or brownian dynamics ) @xcite .. Please generate the next two sentences of the article

time - dependent and dynamic properties , on the other hand , are expected in general to depend on the specific microscopic transport mechanisms . nevertheless , some features associated with the collective , long - time behavior of the system also seem to be rather insensitive to the microscopic short - time dynamics .

Suppose that you have an abstract for a scientific paper: the liquid droplet formula is applied to an analysis of the properties of geometrical ( anti)clusters formed in su(2 ) gluodynamics by the polyakov loops of the same sign . using this approach , we explain the phase transition in su(2 ) gluodynamics as a transition between two liquids during which one of the liquid droplets ( the largest cluster of a certain polyakov loop sign ) experiences a condensation , while another droplet ( the next to the largest cluster of the opposite sign of polyakov loop ) evaporates . the clusters of smaller sizes form two accompanying gases , which behave oppositely to their liquids . the liquid droplet formula is used to analyze the size distributions of the gas ( anti)clusters . the fit of these distributions allows us to extract the temperature dependence of surface tension and the value of fisher topological exponent @xmath0 for both kinds of gaseous clusters . it is shown that the surface tension coefficient of gaseous ( anti)clusters can serve as an order parameter of the deconfinement phase transition in su(2 ) gluodynamics . the fisher topological exponent @xmath0 of ( anti)clusters is found to have the same value @xmath1 . this value disagrees with the famous fisher droplet model , but it agrees well with an exactly solvable model of nuclear liquid - gas phase transition . this finding may evidence for the fact that the su(2 ) gluodynamics and this exactly solvable model of nuclear liquid - gas phase transition are in the same universality class . + * kewords : * geometrical clusters , size distributions , liquid droplet model formula , surface tension . And you have already written the first three sentences of the full article: the lattice formulation of quantum chromodynamics ( qcd ) is presently considered as the only first principle tool to investigate a transition between the confined and deconfined states of strongly interacting matter . such a phase transition ( pt ) is also expected in a pure non abelian su(n ) gauge theory which is known as gluodynamics . the svetitsky - jaffe hypothesis [ ] relates the deconfinement pt in ( d+1)-dimensional su(n ) gluodynamics to the magnetic pt in the d - dimensional z(n ) symmetric spin model .. Please generate the next two sentences of the article

the key element of this correspondence is that the role of spin in the original su(n ) gluodynamics is played by the so called polyakov loop . the latter is interpreted as the time propagator of an infinitely heavy static quark . a high level of understanding of the spin systems along with the svetitsky - jaffe hypothesis led to a significant progress in studies of the su(n ) gluodynamics properties in the pt vicinity .

Suppose that you have an abstract for a scientific paper: x - ray images and gas temperatures taken from a deep @xmath0200 ks chandra observation of the centaurus cluster are presented . multiple inner bubbles and outer semicircular edges are revealed , together with wispy filaments of soft x - ray emitting gas . the frothy central structure and eastern edge are likely due to the central radio source blowing bubbles in the intracluster gas . the semicircular edges to the surface brightness maps 32 kpc to the east and 17.5 kpc to the west are marked by sharp temperature increases and abundance drops . the edges could be due to sloshing motions of the central potential , or are possibly enhanced by earlier radio activity . the high abundance of the innermost gas ( about 2.5 times solar ) limits the amount of diffusion and mixing taking place . ps . = -0.4 in x - rays : galaxies galaxies : clusters : individual : centaurus intergalactic medium . And you have already written the first three sentences of the full article: the centaurus cluster ( abell 3526 ) is x - ray bright , being the nearest cluster ( redshift @xmath1 ) with a 210 kev luminosity exceeding @xmath2 . our earlier 31.7 ks chandra image of the centaurus cluster revealed a complex structure in the innermost few arcmin of the core , centred on the brightest cluster galaxy ngc4696 ( sanders & fabian 2002 ) . the iron abundance of the gas was found to peak at a radius of about 1 arcmin from the centre .. Please generate the next two sentences of the article

the temperature drops from 3.5 to about 1 kev over this whole region . a plume - like structure swirls clockwise to the ne beyond which there is an abrupt temperature increase ( i.e. a cold front ) . the central x - ray emission is surrounded by marked dips in emission , or bubbles , which coincide with the complex radio source ( taylor , fabian & allen 2002 ) .

Suppose that you have an abstract for a scientific paper: we present new , ntt longslit spectroscopy of the b[e ] supergiant in the binary system r4 in the small magellanic cloud . the data show extended , forbidden n and s emissions which are typical signatures of circumstellar matter . their extension along the space axis of the slit defines an angular size of 8.6@xmath0 which translates into a linear size of 2.4 pc . the n emission lines also show the velocity structure of a bipolar outflow expanding at 100 km s@xmath1 on average . this implies that , for a measured radius of 1.2 pc , the outflow originated about 1.2 @xmath2 10@xmath3 yr ago . the line flux ratio [ nii]6584/[sii]6717 indicates that the nebula is nitrogen enriched and therefore it has been ejected from the central star . this is the first bipolar , ejection nebula detected around a well - established b[e ] supergiant . the bipolar morphology and the chemical enrichment shown by the nebula associated with r4 are consistent with the picture of a binary merger ( langer & heger 1998 ) , in which r4 was originally a system composed by a close pair and a third star ( the observed a companion ) . the close pair merged into a single star and the merging process produced a circumstellar nebula that was later shaped by the ensueing b star wind . since the bipolar morphology , the kinematics and the enriched chemical composition make the nebula surrounding r4 very similar to the observed lbv nebulae , our findings imply that at least a few lbv outbursts and nebulae might well be the result of the merging process of two massive stars . . And you have already written the first three sentences of the full article: the class of b[e ] supergiants consists of about 20 luminous evolved b stars with a rich emission line spectrum and a strong infrared excess ( zickgraf et al . 1986 , lamers et al . most of the confirmed members of this class are located in the magellanic clouds , mainly for two reasons : the luminosities of the galactic objects can not be precisely determined due to the uncertain distances , and the difficulty to resolve the objects of this class from other b - type emission line stars ( be stars , herbig be stars , and other types of b[e ] stars ) .. Please generate the next two sentences of the article

gummersbach et al . ( 1995 ) were able to place 14 magellanic cloud b[e ] supergiants in the hr diagram .

Suppose that you have an abstract for a scientific paper: we present new results with a prototype detector that is being developed by the dmtpc collaboration for the measurement of the direction tag ( ) of dark matter wind . we use neutrons from a source to create low - momentum nuclear recoils in elastic scattering with the residual gas nuclei . the recoil track is imaged in low - pressure time - projection chamber with optical readout . we measure the ionization rate along the recoil trajectory , which allows us to determine the direction tag of the incoming neutrons . . And you have already written the first three sentences of the full article: the non - baryonic dark matter in the form of weakly interacting massive particles ( wimps ) still eludes detection despite recent achievements in the detection technology @xcite . aside from scaling up the size of existing detectors , the improvement in the detection sensitivity is possible by detecting the direction of the incoming dark matter particles . as the earth moves in the galactic halo , the dark matter particles appear to come from cygnus constellation .. Please generate the next two sentences of the article

the direction tag of the of the incoming particle , often referred to as the effect , increases the sensitivity of a directional detector by one order of magnitude @xcite . in this paper we present improved results for tagging the direction of low - energy nuclear recoils created by neutrons from a @xmath0cf source by using a time - projection chamber with optical readout .

Suppose that you have an abstract for a scientific paper: this paper focuses on studying the multilevel monte carlo method recently introduced by giles [ _ oper . res . _ * 56 * ( 2008 ) 607617 ] which is significantly more efficient than the classical monte carlo one . our aim is to prove a central limit theorem of lindeberg feller type for the multilevel monte carlo method associated with the euler discretization scheme . to do so , we prove first a stable law convergence theorem , in the spirit of jacod and protter [ _ ann . probab . _ * 26 * ( 1998 ) 267307 ] , for the euler scheme error on two consecutive levels of the algorithm . this leads to an accurate description of the optimal choice of parameters and to an explicit characterization of the limiting variance in the central limit theorem of the algorithm . a complexity of the multilevel monte carlo algorithm is carried out . . . And you have already written the first three sentences of the full article: in many applications , in particular in the pricing of financial securities , we are interested in the effective computation by monte carlo methods of the quantity @xmath0 , where @xmath1 is a diffusion process and @xmath2 a given function . the monte carlo euler method consists of two steps . first , approximate the diffusion process @xmath3 by the euler scheme @xmath4 with time step @xmath5 . then approximate @xmath6 by @xmath7 , where @xmath8 is a sample of @xmath9 independent copies of @xmath10 .. Please generate the next two sentences of the article

this approximation is affected , respectively , by a discretization error and a statistical error @xmath11 on one hand , talay and tubaro @xcite prove that if @xmath2 is sufficiently smooth , then @xmath12 with @xmath13 a given constant and in a more general context , kebaier @xcite proves that the rate of convergence of the discretization error @xmath14 can be @xmath15 for all values of @xmath16 $ ] ( see , e.g. , kloeden and platen @xcite for more details on discretization schemes ) . on the other hand , the statistical error is controlled by the central limit theorem with order @xmath17 .

Suppose that you have an abstract for a scientific paper: the wide - field high - resolution infrared telescope ( white ) will be dedicated in the first years of its life to carrying out a few ( well focused in terms of science objectives and time ) legacy surveys . white would have an angular resolution of @xmath0 homogeneous over @xmath1 sq . deg . in the wavelength range @xmath2 to @xmath3 , which means that we will very efficiently use all the available observational time during night time and day time . moreover , the deepest observations will be performed by summing up shorter individual frames . we will have a temporal information that can be used to study variable objects . the three key science objectives of white are : 1 ) a complete survey of the magellanic clouds to make a complete census of young stellar objects in the clouds and in the bridge and to study their star formation history and the link with the milky way . the interaction of the two clouds with our galaxy might the closest example of a minor merging event that could be the main driver of galaxy evolution in the last 5 gyrs . 2 ) the building of the first sample of dusty supernovae at @xmath4 in the near infrared range ( @xmath5 ) to constrain the equation of state from these obscured objects , study the formation of dust in galaxies and build the first high resolution sample of high redshift galaxies observed in their optical frame 3 ) a very wide weak lensing survey over that would allow to estimate the equation of state in a way that would favourably compete with space projects . . And you have already written the first three sentences of the full article: from the very first days of astrophysics , astronomers have tried to increase their understanding of the universe by building more and more powerful telescopes . however , there is another way to increase the performances which consists in keeping more or less the same type of instruments but by to install them on an observational site presenting better characteristics in terms of background , transparency , image quality , etc . this quest led astronomers to build telescopes on secluded , remote sites on mountain tops or even to launch them in space .. Please generate the next two sentences of the article

however , if we try to summarize these characteristics , keywords are probably cold , dry , stable , high , dark ( wavelength dependent ) and it seems that there is one site on earth that qualifies for all of them : antarctica . to make the best use of the above exceptional characteristics , we propose to build a wide - field ( 0.5-degree in diameter ) high - resolution ( @xmath6 arcsec using ground layer adaptive optics ) infrared ( from 0.8 to 5 @xmath7 ) 2.4-m telescope that we call white . quite a number of science topics can take advantage of those figures .

Suppose that you have an abstract for a scientific paper: a new model for neutrino oscillations is introduced , in which mass - like behavior is seen at high energies , but various behavior can be predicted at low energies . the model employs no neutrino masses , but instead relies on the lorentz - violating parameters @xmath0 and @xmath1 . oscillations into sterile neutrinos and into antineutrinos are also considered . . And you have already written the first three sentences of the full article: neutrino oscillations have been experimentally observed in a variety of situations , and are among the first evidence of physics beyond the standard model . typically , these oscillations are explained by attributing mass to neutrinos ; however , not all experiments can be explained using the same masses - notably , lsnd@xcite and miniboone@xcite require a larger mass - squared difference than the other experiments , and can not be explained using a three - flavor theory of mass . furthermore , recent results at minos and miniboone have hinted at an asymmetry between neutrinos and antineutrinos @xcite , which would be evidence for lorentz violation . it has already been shown that models incorporating lorentz violations can reproduce many of the results of the mass model@xcite .. Please generate the next two sentences of the article

examples include the bicycle model@xcite and the tandem model@xcite . here , a new model is introduced to attempt to explain these experiments .

Suppose that you have an abstract for a scientific paper: we calculate limits on the trilinear soft - breaking parameter , @xmath0 , in the minimal supersymmetric standard model by requiring the absence of nonzero top squark vacuum expectation values . assuming a low @xmath1 , which implies a large top yukawa coupling , we also calculate one - loop corrections to the effective potential . the resulting numerical calculations of the charge / color breaking limits are presented as best - fit surfaces . we compare these results with the analytical limit , @xmath2 , and find that although this is a good estimate of the charge / color breaking bounds for a simplified model of the top sector , stricter bounds are found by a numerical minimization of the minimal supersymmetric standard model potential . . And you have already written the first three sentences of the full article: the minimal supersymmetric standard model ( mssm ) may be described by a lagrangian containing interactions consistent with invariance under the gauge group @xmath3 and global supersymmetry plus a lagrangian containing a restricted set of soft supersymmetry breaking terms @xcite . these terms break supersymmetry while maintaining a useful property of a supersymmetric theory , namely the cancellation of quadratic divergences @xcite . the absence of these divergences is necessary in order to define the renormalized mass of a fundamental scalar , such as the higgs boson , without a fine - tuning of the cancellation between the bare mass and the scalar self - energy @xcite .. Please generate the next two sentences of the article

the presence of fundamental scalar fields in the mssm , besides the higgs bosons , leads to the possibility that these fields may acquire non - zero vacuum expectation values ( vevs ) . since this would violate the conservation of color and/or electric charge symmetry , this leads to forbidden regions of the parameter space of the theory .

Suppose that you have an abstract for a scientific paper: we present the final analysis of the european large area iso survey ( elais ) 15 @xmath0 m observations , carried out with the isocam instrument on board the infrared space observatory ( iso ) . the data reduction method , known as lari method , is based on a mathematical model of the detector s behaviour and was specifically designed for the detection of faint sources in iso - cam / phot data . the method is fully interactive and leads to very reliable and complete source lists . the resulting catalogue includes 1923 sources detected with @xmath1 in the flux range and over an area of 10.85 split into four fields , making it the largest non - serendipitous extragalactic source catalogue obtained to date from iso data . this paper presents the concepts underlying the data reduction method together with its latest enhancements . the data reduction process , the production and basic properties of the resulting catalogue are then discussed . [ firstpage ] infrared : galaxies galaxies : formation , evolution , active , starburst cosmology : observations methods : data analysis catalogues . . And you have already written the first three sentences of the full article: the infrared astronomical satellite ( iras , * ? ? ? * ; * ? ? ? * ) was extremely successful in characterizing for the first time the global properties of the mid- and far - infrared sky , carrying out an all - sky survey at wavelengths of 12 , 25 , 60 and 100 @xmath0 m and leading to discoveries such as those of luminous , ultraluminous and hyperluminous infrared galaxies ( lirgs , ulirg and hlirgs , respectively ) , a substantial population of evolving starbursts and the detection of large - scale structure in the galaxy distribution @xcite . unfortunately , the iras view was typically limited to the very local universe ( @xmath2 ) , thus hampering statistical studies of infrared - luminous galaxies at cosmological redshifts . only few sources were detected by iras at higher redshifts , typically ulirgs magnified by gravitational lenses , like f10214 + 4724 ( @xmath3 , * ? ? ? * ) .. Please generate the next two sentences of the article

in particular only about 1000 galaxies were detected all over the sky in iras 12 band . infrared source counts based on iras data @xcite showed some marginally significant excess of faint sources with respect to no evolution models @xcite , but not enough statistics and dynamic range in flux to discriminate between evolutionary scenarios were available . although conceived as an observatory - type mission , the infrared space observatory ( iso , * ? ? ?

Suppose that you have an abstract for a scientific paper: we propose a physical model for the nonlinear inelastic mechanics of sticky biopolymer networks with potential applications to inelastic cell mechanics . it consists in a minimal extension of the glassy wormlike chain ( ) model , which has recently been highly successful as a quantitative mathematical description of the viscoelastic properties of biopolymer networks and cells . to extend its scope to nonequilibrium situations , where the thermodynamic state variables may evolve dynamically , the is furnished with an explicit representation of the kinetics of breaking and reforming sticky bonds . in spite of its simplicity the model exhibits many experimentally established non - trivial features such as power - law rheology , stress stiffening , fluidization , and cyclic softening effects . . And you have already written the first three sentences of the full article: in many studies of cell mechanics and dynamics , the cell is characterized as a viscoelastic body @xcite . it is an intriguing question to what extent such mechanical behaviour can be rationalized in terms of comparatively simple polymer physics models . in this respect , the comparison of cell rheological data and minimalistic _ in vitro _ reconstituted constructs of the cytoskeleton , such as pure actin solutions @xcite or crosslinked actin networks @xcite , has recently provided many new insights .. Please generate the next two sentences of the article

important progress has also been achieved in the development of phenomenological mathematical descriptions . this includes approaches related to the tube model @xcite , tensegrity - based approaches @xcite , effective - medium models @xcite , and some others @xcite . in particular

Suppose that you have an abstract for a scientific paper: the electrocaloric effect ( ece ) in normal and relaxor ferroelectrics is investigated in the framework of a thermodynamic approach based on the maxwell relation and a landau - type free energy model . the static dielectric response of relaxors is described by the spherical random bond random field model , yielding the first landau coefficient @xmath0 , which differs from the usual expression for ferroelectrics . the fourth - order coefficient @xmath1 is treated as a phenomenological parameter , which is either positive or negative due to the anisotropy of the stress - mediated coupling between the polar nanoregions . when @xmath2 , the maximum ece in a relaxor is predicted near the critical point in the temperature - field phase diagram , whereas in a ferroelectric it occurs at the first order phase transition . the theoretical upper bound on the ece temperature change is estimated from the values of saturated polarization , effective curie constant , and specific heat of the material . . And you have already written the first three sentences of the full article: several articles have recently focused on the electrocaloric effect ( ece ) in ferroelectrics and related materials,@xcite which bears analogy with the well known magnetocaloric effect ( mce).@xcite here we investigate the mechanisms of ece in relaxor ferroelectrics , to be referred to as _ relaxors _ and normal ferroelectrics ( or _ ferroelectrics _ ) , and discuss the specific features of these two groups of materials . in particular , we will discuss the possibility of achieving a giant ece in bulk inorganic relaxors and ferroelectric materials as well as in organic polymers . these systems offer the prospect of practical applications , such as miniaturized and energy efficient cooling devices , without the need for large electric currents commonly associated with the mce . a crucial physical quantity in ece is the change of entropy of a polar material under the application and/or removal of an external electric field .. Please generate the next two sentences of the article

for example , when the electric field is turned on isothermally , the elementary dipolar entities in the system will become partially ordered and the entropy will be lowered . the entropy lowering of the dipolar subsystem is then compensated by an increase of the temperature of the total system , which characterizes the ece .

Suppose that you have an abstract for a scientific paper: the accurate o , mg and fe abundances derived in previous papers of this series from a homogenous reanalysis of high quality data for a large sample of stars are combined with stellar kinematics in order to discuss the history of star formation in the solar neighborhood . we found that the fe / o and fe / mg abundance ratios are roughly constant in the ( inner ) halo and the thick disk ; this means that the timescale of halo collapse was shorter than or of the same order of typical lifetime of progenitors of type ia sne ( @xmath0 gyr ) , this conclusion being somewhat relaxed ( referring to star formation in the individual fragments ) in an accretion model for the galaxy formation . both fe / o and fe / mg ratios raised by @xmath1 dex while the o / h and mg / h ratios hold constant during the transition from the thick to thin disk phases , indicating a sudden decrease in star formation in the solar neighbourhood at that epoch . these results are discussed in the framework of current views of galaxy formation ; they fit in a scenario where both dissipational collapse and accretions were active on a quite similar timescale . 12c13@xmath2c/@xmath3c enth . And you have already written the first three sentences of the full article: observations of our and outer galaxies allowed to identify various galactic populations : the halo , the thick disk , the thin disk , and the bulge . a model for the evolution of galaxies should explain the origin and properties of these populations , as well as other basic observations like e.g. the relation of hubble types with local environment , in a unifying scheme . current models for galaxy formation broadly divide into two families : those considering a dissipational collapse ( eggen et al . 1962 ; larson 1974 ) ; and those which consider galaxies as the results of the accretion of individual fragments undergoing ( some ) indipendent chemical and dynamical evolution ( toomre & toomre 1972 ; searle & zinn 1978 ) . the transition between the halo and disk phases is continuous in smooth _ dissipational collapse _ models , while disk formation is a secondary mechanism in _ accretion _ ones .. Please generate the next two sentences of the article

separation between these two classes of models may be quite artificial : in fact various properties of galaxies , like e.g. the light distribution of ellipticals , are well reproduced by inhomogenous collapses leading to some kind of violent relaxation ( lynden - bell 1967 ) ; on the other side , simulations based on cosmologies dominated by cold dark matter predict that in high density regions galaxies form hierchically by merging of smaller subunits , while in low density ones they form more gradually by infall of diffuse matter ( frenk et al . 1985 ) . within this framework