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5,300 | Suppose that you have an abstract for a scientific paper: kondo systems are usually described by the interaction of strong correlation induced local moment with the highly itinerant conduction electrons . here , we study the role of electron correlations among conduction electrons in the electronic structure of a kondo lattice compound , ce@xmath0cosi@xmath1 , using high resolution photoemission spectroscopy and _ ab initio _ band structure calculations , where co 3@xmath2 electrons contribute in the conduction band .
high energy resolution employed in the measurements helped to reveal signature of ce 4@xmath3 states derived kondo resonance feature at the fermi level and dominance of co 3@xmath2 contributions at higher binding energies in the conduction band .
the line shape of the experimental co 3@xmath2 band is found to be significantly different from that obtained from the band structure calculations within the local density approximations , lda .
consideration of electron - electron coulomb repulsion , @xmath4 among co 3@xmath2 electrons within the lda+@xmath4 method leads to a better representation of experimental results .
signature of electron correlation induced satellite feature is also observed in the co 2@xmath5 core level spectrum .
these results clearly demonstrate the importance of the electron correlation among conduction electrons in deriving the microscopic description of such kondo systems . .
And you have already written the first three sentences of the full article: study of ce - intermetallics have drawn significant attention during past few decades due to the observation of many unusual properties such as valence fluctuations , kondo screening , heavy fermion superconductivity in these systems .
such properties arise due to the proximity of ce 4@xmath3 level to the fermi level leading to strong hybridization between the ce 4@xmath3 states and the conduction electronic states @xcite .
such hybridization often leads to a logarithmic enhancement of electrical resistivity at low temperatures in contrast to a decrease expected in a metal ..
Please generate the next two sentences of the article | this is known as kondo effect . in the case of strong kondo coupling , the antiparallel coupling of the ce moment with the conduction electrons forms a singlet ground state called kondo singlet that manifests as a sharp feature ( kondo resonance feature ) in the electronic structure in the vicinity of the fermi level , @xmath6 .
a lot of success has been achieved to describe these systems within the anderson impurity models . here , the parameters defining the hybridization between 4@xmath3 states and valence electronic states are often estimated using band structure calculations based on local density approximations ( lda)@xcite . |
5,301 | Suppose that you have an abstract for a scientific paper: we describe @xmath0-mle , a fast and efficient local search algorithm for learning finite statistical mixtures of exponential families such as gaussian mixture models .
mixture models are traditionally learned using the expectation - maximization ( em ) soft clustering technique that monotonically increases the incomplete ( expected complete ) likelihood . given prescribed mixture weights , the hard clustering @xmath0-mle algorithm iteratively assigns data to the most likely weighted component and update the component models using maximum likelihood estimators ( mles ) . using the duality between exponential families and bregman divergences ,
we prove that the local convergence of the complete likelihood of @xmath0-mle follows directly from the convergence of a dual additively weighted bregman hard clustering .
the inner loop of @xmath0-mle can be implemented using any @xmath0-means heuristic like the celebrated lloyd s batched or hartigan s greedy swap updates .
we then show how to update the mixture weights by minimizing a cross - entropy criterion that implies to update weights by taking the relative proportion of cluster points , and reiterate the mixture parameter update and mixture weight update processes until convergence .
hard em is interpreted as a special case of @xmath0-mle when both the component update and the weight update are performed successively in the inner loop . to initialize @xmath0-mle ,
we propose @xmath0-mle++ , a careful initialization of @xmath0-mle guaranteeing probabilistically a global bound on the best possible complete likelihood .
# 1#2#1,#2 # 1#2#1,#2 # 1doi:#1 exponential families , mixtures , bregman divergences , expectation - maximization ( em ) , @xmath0-means loss function , lloyd s @xmath0-means , hartigan and wong s @xmath0-means , hard em , sparse em . .
And you have already written the first three sentences of the full article: a statistical mixture model @xcite @xmath1 with @xmath2 weighted components has underlying probability distribution : @xmath3 with @xmath4 and @xmath5 denoting the mixture parameters : the @xmath6 s are positive weights summing up to one , and the @xmath7 s denote the individual component parameters . (
appendix [ sec : notations ] summarizes the notations used throughout the paper . )
mixture models of @xmath8-dimensional gaussians are the most often used statistical mixtures @xcite . in that case.
Please generate the next two sentences of the article | , each component distribution @xmath9 is parameterized by a mean vector @xmath10 and a covariance matrix @xmath11 that is symmetric and positive definite .
that is , @xmath12 . |
5,302 | Suppose that you have an abstract for a scientific paper: we study the relationship between decaying active region magnetic fields , coronal holes and the global coronal magnetic structure using global oscillations network group ( gong ) synoptic magnetograms , solar terrestrial relations observatory ( stereo ) extreme ultra - violet ( euv ) synoptic maps and coronal potential - field source - surface ( pfss ) models .
we analyze 14 decaying regions and associated coronal holes occurring between early 2007 and late 2010 , four from cycle 23 and 10 from cycle 24 .
we investigate the relationship between asymmetries in active regions positive and negative magnetic intensities , asymmetric magnetic decay rates , flux imbalances , global field structure and coronal hole formation . whereas new emerging active regions caused changes in the large - scale coronal field , the coronal fields of the 14 decaying active regions only opened under the condition that the global coronal structure remained almost unchanged .
this was because the dominant slowly - varying , low - order multipoles prevented opposing - polarity fields from opening and the remnant active - region flux preserved the regions low - order multipole moments long after the regions had decayed .
thus the polarity of each coronal hole necessarily matched the polar field on the side of the streamer belt where the corresponding active region decayed .
for magnetically isolated active regions initially located within the streamer belt , the more intense polarity generally survived to form the hole . for non - isolated regions ,
flux imbalance and topological asymmetry prompted the opposite to occur in some cases .
= 1 .
And you have already written the first three sentences of the full article: the solar coronal magnetic field is formed by active regions emerging from the solar interior and becoming distributed throughout the atmosphere by flux transport processes ( e.g. , mackay and yeates 2012 ) .
the field can become open to the heliosphere in regions where a single magnetic polarity dominates , including the polar caps and other regions of isolated polarity ( harvey and recely 2002 ) .
wherever the coronal fields extend to great heights , the magnetic tension force can be overcome by the thermal pressure of the expanding coronal plasma , and the field dragged out and opened to form a coronal hole ( parker 1958 ) . in extreme ultraviolet ( euv ) and soft x - rays ( sxr ) coronal holes appear as dark regions whereas in helium images they appear bright ..
Please generate the next two sentences of the article | harvey and recely ( 2002 ) identified three classes of coronal hole : polar coronal holes confined to high latitudes ( @xmath0 , @xmath1 ) ; isolated coronal holes at active latitudes associated with the remnant fields of decayed active regions ; and transient coronal holes that briefly form after coronal mass ejections . from a study of the polar coronal holes during cycles 22 and 23 ,
harvey and recely concluded that polar coronal holes are formed from isolated holes associated with decayed active - region field of trailing polarity . |
5,303 | Suppose that you have an abstract for a scientific paper: based on analysis of the annual averaged relative sunspot number ( asn ) during 1700 2009 , 3 kinds of solar cycles are confirmed : the well - known 11-yr cycle ( schwabe cycle ) , 103-yr secular cycle ( numbered as g1 , g2 , g3 , and g4 , respectively since 1700 ) ; and 51.5-yr cycle . from similarities ,
an extrapolation of forthcoming solar cycles is made , and found that the solar cycle 24 will be a relative long and weak schwabe cycle , which may reach to its apex around 2012 - 2014 in the vale between g3 and g4 .
additionally , most schwabe cycles are asymmetric with rapidly rising - phases and slowly decay - phases .
the comparisons between asn and the annual flare numbers with different goes classes ( c - class , m - class , x - class , and super - flare , here super - flare is defined as @xmath0 x10.0 ) and the annal averaged radio flux at frequency of 2.84 ghz indicate that solar flares have a tendency : the more powerful of the flare , the later it takes place after the onset of the schwabe cycle , and most powerful flares take place in the decay phase of schwabe cycle . some discussions on the origin of solar cycles are presented . .
And you have already written the first three sentences of the full article: it is well known that the sun is an unique star which affect the geo - space environment extremely .
any variations of solar activities may greatly affect many sides of human living , from satellite operations , radio - based communication , navigation systems , electrical power grid , and oil tubes , etc .
therefore , it is very important to understand when and how the solar activity will take place in the near future ..
Please generate the next two sentences of the article | there are many people who had made such endeavors ( hiremath , 2008 ; hathaway , 2009 ; strong , julia , & saba , 2009 ; etc ) . however , we have much of uncertainties ( pesnell , 2008 ) to present the details of the forthcoming solar cycles . the film * 2012 *
reflects public misgivings to the imminent impact of solar fierce eruptions around the year of 2012 . |
5,304 | Suppose that you have an abstract for a scientific paper: a central aim of physics is to describe the dynamics of physical systems .
schrdinger s equation does this for isolated quantum systems .
describing the time evolution of a quantum system that interacts with its environment , in its most general form , has proved to be difficult because the dynamics is dependent on the state of the environment and the correlations with it . for discrete processes , such as quantum gates or chemical reactions
, quantum process tomography provides the complete description of the dynamics , provided that the initial states of the system and the environment are independent of each other .
however , many physical systems are correlated with the environment at the beginning of the experiment . here
, we give a prescription of quantum process tomography that yields the complete description of the dynamics of the system even when the initial correlations are present .
surprisingly , our method also gives quantitative expressions for the initial correlation .
= 1 there is a rich history to the studies of decoherence of quantum systems due to the interactions with the surrounding degrees of freedom . when the dynamics of the system ( @xmath0 ) is markovian it can be described by a master equation @xcite . nowadays
many researchers are interested in systems that are non - markovian , as there is mounting evidence that some natural systems of importance may be non - markovian @xcite and such features may allow to manipulate and control quantum systems in desired ways .
there is also a great deal of interest in systems that are initially correlated with their environments ( @xmath1 ) because non - markovianity and initial system - environment ( @xmath2 ) correlations are intimately related @xcite .
grasping the mathematical and physical aspects of non - markovian systems , especially with initial @xmath2 correlations , has proved to be a tough road .
nevertheless , there is a great deal of progress on deciding whether a system is non - markovian in the....
And you have already written the first three sentences of the full article: qpt is performed out by noting how input states , that span the space of @xmath0 , map to output states .
the key insight in what follows is that it is not the input states of @xmath0 that are relevant , rather it is the preparation procedures itself , i.e. , the preparation map @xmath11 . for a @xmath20 dimensional system
there are @xmath21 linearly independent states that span its space . however , there are @xmath22 linearly independent operations ( preparations ) that span the space of preparations ..
Please generate the next two sentences of the article | if we determine the corresponding output states for a set of linearly independent preparations then by linearity we have can predict the output state for any preparation .
let us denote this map as @xmath23-map . |
5,305 | Suppose that you have an abstract for a scientific paper: despite the conceptional importance of realizing spin liquids in solid states only few compounds are known . on the other side the effect of lattice distortions and anisotropies on the magnetic exchange topology and the fluctuation spectrum
are an interesting problem .
we compare the excitation spectra of the two @xmath0 kagome lattice compounds volborthite and vesignieite using raman scattering .
we demonstrate that even small modifications of the crystal structure may have a huge effect on the phonon spectrum and low temperature properties . .
And you have already written the first three sentences of the full article: the suggestion of a resonating valence bond ground state in spin liquid systems together with possible exotic , fractional spinon excitations has triggered an intense research interest .
@xcite one of the most promising systems for studying these phenomena is the @xmath0 heisenberg antiferromagnet on the kagome lattice .
the ground states proposed by theory for this system include a valence bond crystal @xcite or a resonating valence bond with a gapped @xcite or gapless @xcite excitation spectrum . in several theoretical studies.
Please generate the next two sentences of the article | the raman response of spin liquids on the kagome lattice has been investigated .
the spectrum can consist of low energy modes as well as high energy , broad continua , depending on details of the systems . |
5,306 | Suppose that you have an abstract for a scientific paper: this talk will describe some recent results @xcite regarding the problem of uniqueness in the large ( also known as _
strong cosmic censorship _ ) for the initial value problem in general relativity .
the interest in the issue of uniqueness in this context stems from its relation to the validity of the principle of determinism in classical physics . as will be clear from below , this problem does not really have an analogue in other equations of evolution typically studied .
moreover , in order to isolate the essential analytic features of the problem from the complicated setting of gravitational collapse in which it arises , some familiarity with the conformal properties of certain celebrated special solutions of the theory of relativity will have to be developed .
this talk is an attempt to present precisely these features to an audience of non - specialists , in a way which hopefully will fully motivate a certain characteristic initial value problem for the spherically - symmetric einstein - maxwell - scalar field system .
the considerations outlined here leading to this particular initial value problem are well known in the physics relativity community , where the problem of uniqueness has been studied heuristically @xcite and numerically @xcite . in @xcite , the global behavior of generic solutions to this ivp , and in particular , the issue of uniqueness ,
is completely understood .
only a sketch of the ideas of the proof is provided here , but the reader may refer to @xcite for details . .
And you have already written the first three sentences of the full article: the general theory of relativity is thought to provide the correct classical description for the interaction of gravity with matter .
this description is embodied in a system of partial differential equations on a four dimensional manifold @xmath0 , the so - called _ einstein equations _ , which relate the ricci curvature @xmath1 of an unknown metric @xmath2 to the energy - momentum tensor @xmath3 of matter : @xmath4 to complete the classical picture of a physics based on a collection of fields satisfying a closed system of equations , one must also consider the laws which govern the evolution of the matter fields generating the energy - momentum tensor on the right hand side of @xmath5 .
( one important special case is when there is no matter , the so - called vacuum ..
Please generate the next two sentences of the article | then @xmath5 with vanishing right hand side is a closed system of quasilinear hyperbolic equations . ) in general , one arrives at quite complicated systems of equations .
however , from the perspective of classical physics , all phenomena are in principle described by the solutions of such a system . moreover , for these systems , the initial value problem is natural , just as in classical dynamics . |
5,307 | Suppose that you have an abstract for a scientific paper: we study propagators of diagonal and off - diagonal gluons in the momentum space in maximal abelian gauge of @xmath0 lattice gauge theory .
remaining @xmath1 degrees of freedom are fixed using landau gauge .
we find substantial difference between the propagator of the diagonal and the off - diagonal gluon in the infrared region .
the propagator of the off - diagonal gluon is suppressed in comparison with that of the diagonal gluon at small momenta . in the ultraviolet region
both propagators behave as in nonabelian landau gauge . .
And you have already written the first three sentences of the full article: in lattice numerical studies gauge invariant quantities are usually computed . on the other hand , gauge covariant quantities also provide important information .
the well known examples are quark and gluon propagators , requiring complete gauge fixing , monopoles and p - vortices , which study needs only partial gauge fixing .
the first lattice calculations of the gluon propagator were performed in landau gauge @xcite . nowadays these results are significantly improved , also various gauges are used ( see e.g. @xcite ) ..
Please generate the next two sentences of the article | maximal abelian gauge ( mag ) , used to demonstrate the dual super conductor confinement mechanism , is especially interesting .
propagators in this gauge were not explored carefully enough so far . |
5,308 | Suppose that you have an abstract for a scientific paper: the rings of @xmath0 invariants of configurations of vectors and linear forms in a finite - dimensional complex vector space @xmath1 were explicitly described by hermann weyl in the 1930s .
we show that when @xmath1 is @xmath2-dimensional , each of these rings carries a natural cluster algebra structure ( typically , many of them ) whose cluster variables include weyl s generators . we describe and explore these cluster structures using the combinatorial machinery of tensor diagrams .
a key role is played by the web bases introduced by g. kuperberg . .
And you have already written the first three sentences of the full article: homogeneous coordinate rings of grassmannians are among the most important examples of cluster algebras .
cluster structures in these rings @xcite play a prominent role in applications of cluster theory arising in connection with integrable systems , algebraic lie theory , poisson geometry , teichmller theory , total positivity , and beyond ; see , e.g. , @xcite and references therein . within cluster algebra theory proper ,
grassmannians provide the most concrete and accessible examples of naturally defined cluster algebras of infinite mutation type . despite their importance.
Please generate the next two sentences of the article | , cluster structures on grassmannians are not well understood at all , apart from a few special cases .
just a tiny subset of their cluster variables have been explicitly described ; we do not know which quivers appear in their seeds ; we do not understand the structure of their underlying cluster complexes ; and so on . |
5,309 | Suppose that you have an abstract for a scientific paper: to produce cartographic maps , simplification is typically used to reduce complexity of the map to a legible level . with schematic maps ,
however , this simplification is pushed far beyond the legibility threshold and is instead constrained by functional need and resemblance . moreover ,
stylistic geometry is often used to convey the schematic nature of the map . in this paper
we explore discretized approaches to computing a schematic shape @xmath0 for a simple polygon @xmath1 .
we do so by overlaying a plane graph @xmath2 on @xmath1 as the solution space for the schematic shape .
topological constraints imply that @xmath0 should describe a simple polygon .
we investigate two approaches , _ simple map matching _ and _ connected face selection _ , based on commonly used similarity metrics . with the former , @xmath0 is a simple cycle @xmath3 in @xmath2 and we quantify resemblance via the frchet distance .
we prove that it is np - hard to compute a cycle that approximates the minimal frchet distance over all simple cycles in a plane graph @xmath2 .
this result holds even if @xmath2 is a partial grid graph , if area preservation is required and if we assume a given sequence of turns is specified . with the latter
, @xmath0 is a connected face set in @xmath2 , quantifying resemblance via the symmetric difference .
though the symmetric difference seems a less strict measure , we prove that it is np - hard to compute the optimal face set .
this result holds even if @xmath2 is full grid graph or a triangular or hexagonal tiling , and if area preservation is required .
moreover , it is independent of whether we allow the set of faces to have holes or not . .
And you have already written the first three sentences of the full article: cartographic maps are an important tool for exploring , analyzing and communicating data in their geographic context .
effective maps show their main information as prominently as possible .
map elements that are not relevant to the map s purpose are abstracted or fully omitted . in _.
Please generate the next two sentences of the article | schematic maps _ , the abstraction is taken to `` extreme '' levels , representing complex geographic elements with only a few line segments .
in addition to highlighting the main aspects of the map , they are useful to avoid an `` illusion of accuracy '' @xcite which may arise when showing data on a detailed map : the schematic appearance acts as a visual cue of distortion , imprecision or uncertainty . |
5,310 | Suppose that you have an abstract for a scientific paper: graph polynomials which are definable in monadic second order logic ( @xmath0 ) on the vocabulary of graphs are fixed - parameter tractable ( @xmath1 ) with respect to clique - width .
in contrast , graph polynomials which are definable in @xmath0 on the vocabulary of hypergraphs are fixed - parameter tractable with respect to tree - width , but not necessarily with respect to clique - width .
no algorithmic meta - theorem is known for the computation of graph polynomials definable in @xmath0 on the vocabulary of hypergraphs with respect to clique - width .
we define an infinite class of such graph polynomials extending the class of graph polynomials definable in @xmath0 on the vocabulary of graphs and prove that they are fixed - parameter polynomial time ( @xmath2 ) computable , i.e. that they can be computed in time @xmath3 , where @xmath4 is the number of vertices and @xmath5 is the clique - width . .
And you have already written the first three sentences of the full article: in recent years there has been growing interst in graph polynomials , functions from graphs to polynomial rings which are invariant under isomorphism .
graph polynomials encode information about the graphs in a compact way in their evaulations , coeffcients , degree and roots .
therefore , efficient computation of graph polynomials has received considerable attention in the literature . since most graph polynomials which naturally arise are @xmath6-hard to compute ( see e.g. @xcite ) , a natural perspective under which to study the complexity of graph polynomials.
Please generate the next two sentences of the article | is that of _
parameterized complexity_. parameterized complexity is a successful approach to tackling @xmath7-hard problems @xcite , by measuring complexity with respect to an additional _ parameter _ of the input ; we will be interested in the parameters tree - width and clique - width . |
5,311 | Suppose that you have an abstract for a scientific paper: we develop an analytical approach for non - abelian gauge models within the plaquette representation where the plaquette matrices play the role of the fundamental degrees of freedom .
we start from the original batrouni formulation and show how it can be modified in such a way that each non - abelian bianchi identity contains two connectors instead of four . using this representation
we construct the low - temperature expansion for @xmath0 and @xmath1 models on a finite lattice and discuss its uniformity in the volume .
next , we derive a dual representation for the t hooft loop in the @xmath2 model and describe monopoles in the maximal axial gauge . .
And you have already written the first three sentences of the full article: lattice gauge theory ( lgt ) can be formulated in many equivalent ways . the original wilson formulation is given in terms of group valued matrices on links as fundamental degrees of freedom @xcite .
the partition function reads @xmath3 \ } \ , \label{partfunc}\ ] ] where @xmath4 is the standard wilson action and the integral is calculated over the haar measure on the group at every link of the lattice .
several years later the dual representation for abelian lgt s was constructed in @xcite ..
Please generate the next two sentences of the article | extensions to nonabelian groups have been proposed in ninetees in @xcite-@xcite .
a closely related approach is so - called plaquette representation invented in the continuum theory by m. halpern @xcite and extended to the lattice models in @xcite . in this representation |
5,312 | Suppose that you have an abstract for a scientific paper: democracy among the same type of particles is a useful paradigm in studying masses and interactions of particles with supersymmetry(susy ) or without susy .
this simple idea predicts the presence of massless particles .
we attempt to use one of these massless pseudoscalar particles as generating the cosmological dark energy(de ) potential . to achieve the extremely shallow potential of de , the pseudoscalar boson is required not to couple to the qcd anomaly .
so , we consider two pseudoscalars , one coupling to the qcd anomaly ( _ i.e .
_ qcd axion ) and the other not coupling to the qcd anomaly . to obtain these two pseudoscalars , we introduce two approximate global u(1 ) symmetries to realize them as the pseudo - goldstone bosons of the spontaneously broken u(1 ) s .
these global symmetries are dictated by a gravity respected discrete symmetry .
specifically , we consider an @xmath0 example , and attempt to obtain the de scale in terms of two observed fundamental mass scales , the grand unification scale @xmath1 and the electroweak scale @xmath2 . .
And you have already written the first three sentences of the full article: massless particles around the electroweak(ew ) scale determine physical laws observed around us .
the recent discovery of the higgs boson @xcite almost confirms the standard model(sm ) spectrum below about 1 tev .
obtaining such a massless spectrum theoretically has a long history under the name of the ` gauge hierarchy problem ' @xcite . since quarks and leptons have the chiral structure , they can be kept massless down to the tev scale ..
Please generate the next two sentences of the article | however , the higgs boson is difficult to be kept massless in the sm framework .
the most studied solution of the gauge hierarchy problem has been supersymmetry(susy ) . even in the minimally supersymmetrized sm ( mssm ) |
5,313 | Suppose that you have an abstract for a scientific paper: we present infrared photometry and optical and infrared spectroscopy of the recently - discovered , extremely luminous nearby quasar pds 456 .
a number of broad emission features are seen in the near - infrared which we are unable to identify .
we measure a more accurate redshift from a narrow forbidden emission line and compare the optical infrared spectrum to that of 3c 273 .
the close similarity suggests that pds 456 is a radio - quiet analogue of 3c 273 , although radio observations do not support this idea . #
1to 0pt#1 galaxies : active quasars : individual ( pds 456 ) galaxies : distances and redshifts quasars : emission lines galaxies : photometry radio continuum : galaxies .
And you have already written the first three sentences of the full article: torres et al . ( 1997 ; hereafter t97 ) reported the discovery of a new bright ( @xmath0 ) quasar at relatively low redshift ( @xmath1 ) .
this object , called pds 456 , was discovered in the pico dos dias survey for young stellar objects , which uses optical magnitude and _ iras _ colours as selection criteria .
although somewhat fainter than 3c 273 , pds 456 lies close to the galactic centre and is seen through @xmath2mag of extinction ( t97 ) , and it is therefore intrinsically more luminous ..
Please generate the next two sentences of the article | it is , however , radio - quiet , with @xmath3mjy ( griffith et al .
1994 ) and @xmath4mjy ( pds 456 can be identified with nvss j172819@xmath5141555 ; condon et al . |
5,314 | Suppose that you have an abstract for a scientific paper: the sirtf nearby galaxy survey is a comprehensive infrared imaging and spectroscopic survey of 75 nearby galaxies .
its primary goal is to characterize the infrared emission of galaxies and their principal infrared - emitting components , across a broad range of galaxy properties and star formation environments .
sings will provide new insights into the physical processes connecting star formation to the interstellar medium properties of galaxies , and provide a vital foundation for understanding infrared observations of the distant universe and ultraluminous and active galaxies . the galaxy sample and observing strategy
have been designed to maximize the scientific and archival value of the data set for the sirtf user community at large .
the sirtf images and spectra will be supplemented by a comprehensive multi - wavelength library of ancillary and complementary observations , including radio continuum , hi , co , submillimeter , @xmath0 , h@xmath1 , paschen-@xmath1 , ultraviolet , and x - ray data .
this paper describes the main astrophysical issues to be addressed by sings , the galaxy sample and the observing strategy , and the sirtf and other ancillary data products . .
And you have already written the first three sentences of the full article: nearly half of the bolometric luminosity of the local universe is channeled through the mid- and far - infrared emission of galaxies ; this spectral region directly probes the youngest star - forming regions and their associated interstellar gas and dust .
however , existing infrared ( ir ) instruments have only begun to probe the full ranges in star formation rates , interstellar medium ( ism ) properties , and dynamical environments found in external galaxies .
the sirtf nearby galaxies survey ( sings ) is designed to characterize the infrared emission of present - day galaxies and probe the full range of star formation environments found locally , including regions that until now have been inaccessible at infrared wavelengths ..
Please generate the next two sentences of the article | the observations include imaging and low - resolution spectroscopy of 75 nearby galaxies ( @xmath2 mpc ) , and high - resolution spectroscopy of their centers and a representative set of extranuclear infrared - emitting regions .
these data will be supplemented with an extensive library of ground- and space - based data at other wavelengths . |
5,315 | Suppose that you have an abstract for a scientific paper: a configuration of @xmath0 points in @xmath1 is called _ typical _ if it has no collinear triples and no coconic sextuples of points .
we show that there exist @xmath2 deformation classes of such configurations .
this yields classification of real aronhold sets . .
And you have already written the first three sentences of the full article: projective configurations of points on the plane is a classical subject in algebraic geometry and its history in the context of linear systems of curves can be traced back to 18th century ( g.cramer , l.euler , etc . ) . in modern times ,
projective configurations are studied both from algebro - geometric viewpoint ( geometric invariant theory , hilbert schemes , del pezzo surfaces ) , and from combinatorial geometric viewpoint ( matroid theory ) . in the latter approach
just linear phenomena are essential , and in particular , a generic object of consideration is a _ simple @xmath4-configuration _ , that is a set of @xmath4 points in @xmath1 in which no triple of points is collinear ..
Please generate the next two sentences of the article | the dual object is _ a simple @xmath4-arrangement _ , that is a set of @xmath4 real lines containing no concurrent triples .
a combinatorial characterization of a simple @xmath4-arrangement is its _ oriented matroid _ , which is roughly speaking a description of the mutual position of its partition polygons . for simple n - configurations |
5,316 | Suppose that you have an abstract for a scientific paper: diffusion may obliterate fluctuation signals of the qcd phase transition in nuclear collisions at sps and rhic energies . we propose a hyperbolic diffusion equation to study the dissipation of net charge fluctuations .
this equation is needed in a relativistic context , because the classic parabolic diffusion equation violates causality .
we find that causality substantially limits the extent to which diffusion can dissipate these fluctuations . .
And you have already written the first three sentences of the full article: net - charge fluctuations are measured in nuclear collisions by many rhic and sps experiments @xcite .
conserved quantities such as net electric charge , baryon number , and strangeness can fluctuate when measured in limited rapidity intervals .
these fluctuations occur mainly because the number of produced particles varies with each collision event due to differences in impact parameter , energy deposition , and baryon stopping ..
Please generate the next two sentences of the article | a variety of interesting dynamic effects can also contribute to these fluctuations @xcite .
in particular , fluctuations of mean @xmath0 , net charge , and baryon number may probe the hadronization mechanism of the quark - gluon plasma @xcite . |
5,317 | Suppose that you have an abstract for a scientific paper: the munu experiment was carried out at the bugey nuclear power reactor .
the aim was the study of @xmath0 elastic scattering at low energy .
the recoil electrons were recorded in a gas time projection chamber , immersed in a tank filled with liquid scintillator serving as veto detector , suppressing in particular compton electrons . the measured electron recoil spectrum is presented .
upper limits on the neutrino magnetic moment were derived and are discussed . .
And you have already written the first three sentences of the full article: the munu experiment was designed to study @xmath1 scattering at low energy , probing in particular the magnetic moment of the neutrino .
the detector was set up near a nuclear power reactor in bugey ( france ) serving as antineutrino source .
we report here on an analysis of data corresponding to 66.6 days of live time reactor - on and 16.7 days reactor - off ..
Please generate the next two sentences of the article | many experiments now show that neutrinos have masses , and that the weak eigenstates @xmath2 are superpositions of the mass eigenstates @xmath3 : @xmath4 intense work is being done to determine more precisely the mixings @xmath5 and the masses @xmath6 .
besides masses , neutrinos can have magnetic moments . as shown in ref . |
5,318 | Suppose that you have an abstract for a scientific paper: we present a swarm model of brownian particles with harmonic interactions , where the individuals undergo canonical active brownian motion , i.e. each brownian particle can convert internal energy to mechanical energy of motion .
we assume the existence of a single global internal energy of the system .
numerical simulations show amorphous swarming behavior as well as static configurations .
analytic understanding of the system is provided by studying stability properties of equilibria . .
And you have already written the first three sentences of the full article: the concept of active brownian motion was developed to describe complex motion in various systems @xcite , @xcite .
its main idea is to assume the existence of an additional _ internal _ degree of freedom , called the internal energy @xmath0 , which can be taken up from the environment and converted to energy of motion .
former models only assumed an exchange between the internal energy and the _ kinetic _ energy of motion . in @xcite , we discussed a more general case , where @xmath0 can be also converted to the potential energy of the particle , thus to the _ full _ mechanical energy @xmath1 ..
Please generate the next two sentences of the article | the corresponding stochastic equations for the position @xmath2 and the momentum @xmath3 of the particle read @xmath4 @xmath5 where @xmath6 represents the stochastic noise , satisfying the correlations @xmath7 and therefore describing a completely irregular force .
the constants @xmath8 and @xmath9 remain to be fixed for concrete applications . |
5,319 | Suppose that you have an abstract for a scientific paper: application users have now been experiencing for about a year with the standardized resource brokering services provided by the workload management package of the eu datagrid project ( wp1 ) .
understanding , shaping and pushing the limits of the system has provided valuable feedback on both its design and implementation .
a digest of the lessons , and better practices " , that were learned , and that were applied towards the second major release of the software , is given . .
And you have already written the first three sentences of the full article: the workload management task ( work package 1 , or wp1 ) @xcite of the eu datagrid project @xcite ( also known , and referred to in the following text , as edg ) is mandated to define and implement a suitable architecture for distributed scheduling and resource management in the grid environment . during the first year and a half of the project ( 2001 - 2002 ) , and following a technology evaluation process , edg wp1 defined , implemented and deployed a set of services that integrate existing components , mostly from the condor @xcite and globus @xcite projects .
this was described in more detail at chep 2001 @xcite . in a nutshell , the core job submission component of condorg ( @xcite ) ,
talking to computing resources ( known in datagrid as computing elements , or ces ) via the globus gram protocol , is fundamentally complemented by : * a job requirement matchmaking engine ( called the _ resource broker _ , or rb ) , matching job requests to computing resource status coming from the information system and resolving data requirements against the replicated file management services provided by edg wp2 . *.
Please generate the next two sentences of the article | a job logging and book - keeping service ( lb ) , where a job state machine is kept current based on events generated during the job lifetime , and the job status is made available to the submitting user .
the lb events are generated with some redundancy to cover various cases of loss . |
5,320 | Suppose that you have an abstract for a scientific paper: the issue of asymmetric uncertainties resulting from fits , nonlinear propagation and systematic effects is reviewed .
it is shown that , in all cases , whenever a published result is given with asymmetric uncertainties , the _ value _ of the physical quantity of interest _ is biased _ with respect to what would be obtained using at best all experimental and theoretical information that contribute to evaluate the combined uncertainty .
the probabilistic solution to the problem is provided both in exact and in approximated forms .
# 1 .
And you have already written the first three sentences of the full article: we often see published results in the form @xmath0 where @xmath1 and @xmath2 are _ usually _ positive . and
@xmath2 with all combinations of signs , see public online tables of deep inelastic scattering results.@xcite i want to make clear since the very beginning that it is not my intention to blame experimental or theoretical teams which have reported in the past asymmetric uncertainty , because we are all victims of a bad tradition in data analysis .
at least , when asymmetric uncertainties have been given , there is some chance to correct the result , as described in sec ..
Please generate the next two sentences of the article | [ sec : thumb ] . since some asymmetric contributions to the global uncertainties almost unavoidably happen in complex experiments , i am more worried of collaborations that never arrive to final asymmetric uncertainties , because i must imagine they have symmetrised somehow the result but , i am afraid , without applying the proper shifts to the ` best value ' to take into account asymmetric contributions , as it will be discussed in the present paper . ] as firstly pointed out in ref .
@xcite and discussed in a simpler but more comprehensive way in ref . |
5,321 | Suppose that you have an abstract for a scientific paper: the conformal cosmological model presented by mannheim predicts a negative value for the effective gravitational constant , @xmath0 .
it also involves a scalar field , @xmath1 , which is treated classically . in this paper
we point out that a classical treatment of @xmath1 is inappropriate , because the hamiltonian is non - hermitean , and the theory must be developed in the way pioneered by bender and others .
when this is done , we arrive at a hamiltonian with an energy spectrum that is bounded below , and also a @xmath0 that is positive .
the resulting theory closely resembles the conventional cosmology based on einstein relativity . .
And you have already written the first three sentences of the full article: mannheim @xcite ( henceforth m6 ) has developed a cosmological model ( mm ) based on conformal invariance .
this model has a number of attractive features , but has not so far been accepted as a viable candidate for the correct theory of gravitation , in large part because it predicts , apparently unambiguously , a negative value for the effective gravitational constant , @xmath0 . from this
follows a thermal history markedly different from the usual one , and consequent difficulties in addressing questions such as primordial nucleosynthesis @xcite . in this paper.
Please generate the next two sentences of the article | we point out a mathematical problem in the formulation of the model , and present a new approach that yields a positive @xmath0 , so that the model closely resembles the conventional one .
the mm involves a scalar field , @xmath1 , in a friedmann - robertson - walker ( frw ) background metric . |
5,322 | Suppose that you have an abstract for a scientific paper: in this talk i will discuss non - leptonic @xmath0 decays , in particular how soft - collinear effective field theory ( scet ) can be used to constrain the non - perturbative hadronic parameters required to describe the various observables . .
And you have already written the first three sentences of the full article: the standard model ( sm ) of particle physics has proven to hold up against any experimental tests it has been subjected to so far .
the sm has several striking features for which no underlying principle has been experimentally confirmed to this date .
first , the sm requires the scale of electro - weak symmetry breaking to be of order a few hundred gev , which is many orders of magnitude below the only fundamental scale of nature we know of , the planck scale ..
Please generate the next two sentences of the article | second , to explain the masses and flavor violating transitions of fermions requires the fundamental yukawa matrices to satisfy a very particular scaling , for which no satisfactory symmetry or other underlying principle has been found so far .
while the scale of electro - weak symmetry breaking is known from the measured properties of gauge interactions , the scale of flavor violation could be completely unrelated to that scale . |
5,323 | Suppose that you have an abstract for a scientific paper: decoding sparse quantum codes can be accomplished by syndrome - based decoding using a belief propagation ( bp ) algorithm .
we significantly improve this decoding scheme by developing a new feedback adjustment strategy for the standard bp algorithm . in our feedback procedure ,
we exploit much of the information from stabilizers , not just the syndrome but also the values of the frustrated checks on individual qubits of the code and the channel model .
furthermore we show that our decoding algorithm is superior to belief propagation algorithms using only the syndrome in the feedback procedure for all cases of the depolarizing channel .
our algorithm does not increase the measurement overhead compared to the previous method , as the extra information comes for free from the requisite stabilizer measurements .
shell : bare demo of ieeetran.cls for journals sparse quantum codes , quantum error correction , quantum channels , belief propagation , stabilizers . .
And you have already written the first three sentences of the full article: is limited by noise in channels , but error correction methods can efficiently offset this restriction in both classical @xcite and quantum @xcite cases . at a simple level , multiple copies of the information can be transmitted , and a majority rule can be applied to discern the correct code , but such coding is neither practical nor efficient .
sparse graph coding , such as gallager s low - density parity - check ( ldpc ) codes , offers an efficient alternative that approaches the shannon information limit @xcite .
fortunately quantum coding and decoding strategies can be constructed from their classical counterparts , but unfortunately this mapping from classical to quantum coding can be problematic due to the requirement that quantum codes satisfy the duality - containing condition @xcite ..
Please generate the next two sentences of the article | moreover , due to increased challenges posed by these quantum codes , performance improvement requires further progress in the proposed decoding algorithm @xcite .
the entanglement - assisted ( ea ) stabilizer formalism adds error - free entangled bits as a consumable resource for performing quantum error correction . |
5,324 | Suppose that you have an abstract for a scientific paper: the type - i x - ray bursting low mass x - ray binary was recently detected for the first time in quiescence by wijnands , following a @xmath013 yr outburst which ended in feb 2001 .
we show that the emission area radius for a h atmosphere spectrum ( possibly with a hard power - law component that dominates the emission above 3.5 kev ) is consistent with that observed from other quiescent neutron star transients , = 23(d/8 ) km , and examine possible ir counterparts for . unlike all other known transient neutron stars ( ns ) , the duration of this recent ( and the only observed ) outburst is as long as the thermal diffusion time of the crust .
the large amount of heat deposited by reactions in the crust will have heated the crust to temperatures much higher than the equilibrium core temperature . as a result ,
the thermal luminosity currently observed from the neutron star is dominated not by the core , but by the crust .
this scenario implies that the mean outburst recurrence timescale found by wijnands ( @xmath1 200 yr ) is a lower limit .
moreover , because the thermal emission is dominated by the hot crust , the level and the time evolution of quiescent luminosity is determined mostly by the amount of heat deposited in the crust during the most recent outburst ( for which reasonable constraints on the mass accretion rate exist ) , and is only weakly sensitive to the core temperature . using estimates of the outburst mass accretion rate , our calculations of the quiescent flux immediately following the end of the outburst agree with the observed quiescent flux to within a factor of a few . in this paper
, we present simulations of the evolution of the quiescent lightcurve for different scenarios of the crust microphysics , and demonstrate that monitoring observations ( with currently flying instruments ) spanning from 130 yr can measure the crust cooling timescale and the total amount of heat stored in the crust .
these quantities have not been directly measured for any neutron star .
....
And you have already written the first three sentences of the full article: 40004000 = 1000 # 1
40004000 = 1000 brown , bildsten & rutledge ( * ? ? ?
* bbr98 hereafter ) argued that the core of a transiently accreting neutron star ( ns ) ( for reviews of transient neutron stars , see ) is heated by nuclear reactions deep in the crust during the accretion outbursts ..
Please generate the next two sentences of the article | the core is heated to a steady state in @xmath1 yr ( see for a detailed calculation ) , after which the ns emits a quiescent thermal luminosity ( bbr98 ) @xmath3 where @xmath4 is the time - averaged ( over the ns core thermal timescale ) mass - accretion rate onto the ns , and @xmath5 is the amount of heat deposited in the crust per accreted nucleon (; see for a review ) . for an accretion flux onto the ns ( @xmath6 ) ,
the `` rock bottom '' quiescent flux due to deep crustal heating is then @xmath7 where @xmath8 is the accretion flux averaged over the ns core thermal timescale , and the accretion efficiency @xmath9 for accretion luminosity of @xmath10 . |
5,325 | Suppose that you have an abstract for a scientific paper: despite the dramatic progress made in neutrino oscillation studies recently , several fundamental neutrino parameters remain either unknown or poorly measured .
we discuss in detail a method for their measurement by precision studies of oscillation - caused neutrino energy spectrum distortions , for which a large underwater inverse beta decay detector appears to be a perfect tool .
results determine optimal baselines and necessary exposures in the presence of systematic uncertainties and the unavoidable background from terrestrial antineutrinos . .
And you have already written the first three sentences of the full article: neutrino flavor transformations are determined by the elements of the pmns matrix @xcite and the differences between the squares of neutrino mass eigenvalues .
pmns matrix represents the mixture between flavor and mass eigenstates of neutrinos and is conventionally decomposed as shown in ( [ pmns ] ) .
neutrino oscillation experiments can yield the best estimations for some of those parameters , which has been demonstrated by sno @xcite and kamland @xcite ..
Please generate the next two sentences of the article | @xmath0 \nonumber \\ & = & \left [ \begin{array}{ccc } 1 & 0 & 0 \\ 0 & c_{2 3 } & s_{2 3 } \\ 0 & -s_{2 3 } & c_{2 3 } \end{array } \right ] \left [ \begin{array}{ccc } c_{1 3 } & 0 & s_{1 3}e^{-i\delta } \\ 0 & 1 & 0 \\ -s_{1 3}e^{i\delta } & 0 & c_{1 3 } \end{array } \right ] \nonumber \\ & \times & \left [ \begin{array}{ccc } c_{1 2 } & s_{1 2 } & 0 \\ -s_{1 2 } & c_{1 2 } & 0 \\ 0 & 0 & 1 \end{array } \right ] \left [ \begin{array}{ccc } e^{i\alpha_1/2 } & 0 & 0
\\ 0 & e^{i\alpha_2/2 } & 0 \\ 0 & 0 & 1 \label{pmns } \end{array } \right],\end{aligned}\ ] ] where @xmath1 , @xmath2 , @xmath3 is the phase factor ( non - zero if neutrino oscillation violates cp symmetry ) . @xmath4 and @xmath5 majorana phase factors ( non - zero only if neutrinos are majorana particles ) , to which neutrino oscillation experiments are not sensitive . besides the pmns matrix , neutrino oscillations depend on mass eigenvalues or , more precisely , on the difference between the squared mass eigenvalues . |
5,326 | Suppose that you have an abstract for a scientific paper: we study the optimality of linear precoding for the two - receiver multiple - input multiple - output ( mimo ) gaussian broadcast channel ( bc ) with confidential messages .
secret dirty - paper coding ( s - dpc ) is optimal under an input covariance constraint , but there is no computable secrecy capacity expression for the general mimo case under an average power constraint . in principle , for this case , the secrecy capacity region could be found through an exhaustive search over the set of all possible matrix power constraints . clearly , this search , coupled with the complexity of dirty - paper encoding and decoding , motivates the consideration of low complexity linear precoding as an alternative .
we prove that for a two - user mimo gaussian bc under an input covariance constraint , linear precoding is optimal and achieves the same secrecy rate region as s - dpc if the input covariance constraint satisfies a specific condition , and we characterize the corresponding optimal linear precoders .
we then use this result to derive a closed - form sub - optimal algorithm based on linear precoding for an average power constraint .
numerical results indicate that the secrecy rate region achieved by this algorithm is close to that obtained by the optimal s - dpc approach with a search over all suitable input covariance matrices . .
And you have already written the first three sentences of the full article: the work of wyner @xcite led to the development of the notion of secrecy capacity , which quantifies the maximum rate at which a transmitter can reliably send a secret message to a receiver , without an eavesdropper being able to decode it .
more recently , researchers have considered secrecy for the two - user broadcast channel , where each receiver acts as an eavesdropper for the independent message transmitted to the other .
this problem was addressed in @xcite , where inner and outer bounds for the secrecy capacity region were established ..
Please generate the next two sentences of the article | further work in @xcite studied the multiple - input single - output ( miso ) gaussian case , and @xcite considered the general mimo gaussian case .
it was shown in @xcite that , under an input covariance constraint , both confidential messages can be simultaneously communicated at their respective maximum secrecy rates , where the achievablity is obtained using secret dirty - paper coding ( s - dpc ) . however , under an average power constraint , a computable secrecy capacity expression for the general mimo case has not yet been derived . in principle , the secrecy capacity for this case could be found by an exhaustive search over the set of all input covariance matrices that satisfy the average power constraint @xcite . clearly , the complexity associated with such a search and the implementation of dirty - paper encoding and decoding make such an approach prohibitive except for very simple scenarios , and motivates the study of simpler techniques based on linear precoding . |
5,327 | Suppose that you have an abstract for a scientific paper: ricci flow deformation of cosmological initial data sets in general relativity is a technique for generating families of initial data sets which potentially would allow to interpolate between distinct spacetimes .
this idea has been around since the appearance of the ricci flow on the scene , but it has been difficult to turn it into a sound mathematical procedure . in this expository talk we illustrate , how perelman s recent results in ricci flow theory can considerably improve on such a situation . from a physical point of view
this analysis can be related to the issue of finding a constant curvature template spacetime for the inhomogeneous universe , relevant to the interpretation of observational data and , hence , bears relevance to the dark energy and dark matter debates .
these techniques provide control on curvature fluctuations ( intrinsic backreaction terms ) in their relation to the averaged matter distribution . .
And you have already written the first three sentences of the full article: the ricci flow has been introduced by r. hamilton @xcite with the goal of providing an analytic approach to thurston s geometrization conjecture for three - manifolds @xcite@xmath0 . inspired by the theory of harmonic maps , he considered the geometric evolution equation obtained when one evolves a riemannian metric @xmath1 , on a three - manifold @xmath2 , in the direction of its ricci tensor@xcite @xmath3 , _
i.e. _ @xmath4 in recent years , this geometric flow has gained extreme popularity thanks to the revolutionary breakthroughs of g. perelman @xcite@xmath0 , who , taking the whole subject by storm , has brought to completion hamilton s approach to thurston s conjecture .
the prominent themes recurring in hamilton s and perelman s works converge to a proof that the ricci flow , coupled to topological surgery , provides a natural technique for factorizing and uniformizing a three - dimensional riemannian manifold @xmath5 into locally homogeneous geometries ..
Please generate the next two sentences of the article | this is a result of vast potential use also in theoretical physics , where the ricci flow often appears in disguise as a natural real - space renormalization group flow .
non - linear @xmath6-model theory , describing quantum strings propagating in a background spacetime , affords the standard case study in such a setting @xmath0 . |
5,328 | Suppose that you have an abstract for a scientific paper: a version of scattering theory that was developed many years ago to treat nuclear scattering processes , has provided a powerful tool to study universality in scattering processes involving open quantum systems with underlying classically chaotic dynamics .
recently , it has been used to make random matrix theory predictions concerning the statistical properties of scattering resonances in mesoscopic electron waveguides and electromagnetic waveguides .
we provide a simple derivation of this scattering theory and we compare its predictions to those obtained from an exactly solvable scattering model ; and we use it to study the scattering of a particle wave from a random potential .
this method may prove useful in distinguishing the effects of chaos from the effects of disorder in real scattering processes . .
And you have already written the first three sentences of the full article: interest in the dynamical properties of open quantum systems at mesoscopic and atomic scales has lead to a rebirth of a form of scattering theory which was originally developed to deal with very complicated nuclear collision processes .
the origin of the scattering theory that we consider here came from the recognition that a collision between two nucleons , one of which is very heavy , can lead to the creation of an unstable , but very long - lived , compound nucleus which eventually decays . in the late 1930 s , kapur and peierls @xcite used this fact to formulate a nonperturbative approach to scattering theory in which the compound nucleus was viewed as a stable object which was made unstable by weak coupling to the continuum .
in the late 1940 s , wigner and eisenbud @xcite developed an alternate version of the kapur - peierls theory which lead to the very widely used r - matrix approach to scattering theory @xcite ..
Please generate the next two sentences of the article | the idea behind both these theories is to decompose configuration space into an internal region ( reaction region ) and an external asymptotic scattering region .
as we shall see , this approach can be made clean and rigorous if there is an abrupt ( in configuration space ) transition between the scattering region and the asymptotic region . |
5,329 | Suppose that you have an abstract for a scientific paper: a sample of 4208 objects with magnitude @xmath0 and colors of main sequence a stars have been selected from 370 square degrees of sloan digital sky survey ( sdss ) commissioning observations . the data is from two long , narrow stripes , each with an opening angle of greater than 60@xmath1 , at galactic latitudes @xmath2 on the celestial equator .
relative photometric calibrations good to 2% and consistent absolute photometry allows this uniform sample to be treated statistically over the large area .
an examination of the sample s distribution shows that these stars trace considerable substructure in the halo .
large overdensities of a - colored stars in the north at @xmath3 and in the south at @xmath4 and extending over tens of degrees are present in the halo of the milky way .
@xcite has detected the northern structure from a sample of rr lyraes in the sdss . using photometry to separate the stars by surface gravity ,
both structures are shown to contain a sequence of low surface gravity stars consistent with identification as a blue horizontal branch ( bhb ) .
both structures also contain a population of high surface gravity stars two magnitudes fainter than the bhb stars , consistent with their identification as blue stragglers ( bss ) .
the majority of the high surface gravity stars in the galactic halo may be blue straggler stars like these .
a population of f stars associated with the a star excess in the southern structure is detected ( the f stars in the northern structure at 46 kpc would be too faint for the sdss to detect ) . from the numbers of detected bhb stars , lower limits to the implied mass of the structures are @xmath5 and @xmath6 , though one does not yet know the full spatial extent of the structures . the fact that two such large clumps have been detected in a survey of only 1% of the sky indicates that such structures are not uncommon in the halo .
simple spheroidal parameters are fit to a complete sample of the remaining unclumped bhb stars and yield ( at....
And you have already written the first three sentences of the full article: observations of distinct populations of stars in the milky way galaxy ( young , metal - rich stars in the disk and older , metal - poor stars in the halo ) led ( * ? ? ?
* els ) to propose that the galactic halo formed before the disk , during the rapid collapse of a gas cloud . in this picture , the stars in the halo are approximately the same age , with abundances which increase towards the center of the galaxy .
the model predicts a relatively smooth form and shape for the halo ..
Please generate the next two sentences of the article | simple models , for instance , parameterize the distribution of matter in the galactic halo as a flattened spheroid , where the flattening is given by an axial ratio @xmath10 ( and @xmath11 if triaxiality is considered ) , with a power - law density profile @xmath12 .
as the positions and motions of luminous objects in the galactic halo in principle provide tracers of mass within the halo potential , study of these objects is important for understanding the distribution of dark matter as well as providing clues to the formation of the galaxy . |
5,330 | Suppose that you have an abstract for a scientific paper: we consider a model with competing double - exchange ( ferromagnetic ) and super - exchange ( anti - ferromagnetic ) interactions in the regime where phase separation takes place .
the presence of a long range coulomb interaction frustrates a macroscopic phase separation , and favors microscopically inhomogeneous configurations .
we use the variational hartree - fock approach , in conjunction with monte - carlo simulations to study the geometry of such configurations in a two - dimensional system .
we find that an array of diamond shaped ferromagnetic droplets is the preferred configuration at low electronic densities , while alternating ferromagnetic and anti - ferromagnetic diagonal stripes emerge at higher densities .
these findings are expected to be relevant for thin films of colossal magneto - resistive manganates . .
And you have already written the first three sentences of the full article: in recent years , doped manganese oxides remained at the forefront of theoretical and experimental research@xcite .
the main source of interest in theses systems is the phenomenon of colossal magnetoresistance ( cmr ) , which they exhibit , and that is likely to have important technological applications . in the meantime ,
the underlying basic physics remains elusive , and probably involves the strongly - correlated nature of the doped magnetic oxides ..
Please generate the next two sentences of the article | the cmr in doped manganates is observed for intermediate hole - doping levels , typically @xmath0 , in the temperature region around the transition between low - temperature metallic ferromagnetic ( fm ) and high - temperature insulating paramagnetic phases .
in addition to double - exchange ferromagnetism@xcite , the cmr compounds also possess pronounced antiferromagnetic ( afm ) tendencies , as evident from the afm spin ordering with nel temperatures of about 100 - 200k , observed@xcite at the doping end - points ( @xmath1 and @xmath2 ) . |
5,331 | Suppose that you have an abstract for a scientific paper: the discrete unitary ( reversible ) analogues of the continuous ( irreversible ) tent maps are numerically investigated , in particular , the lengths probability distribution of their periodic orbits .
it is found that its density can be well approximated by the inverse proportional law . .
And you have already written the first three sentences of the full article: as known , many key features of continuous - time chaotic dynamics can be treated in terms of two - dimensional or even one - dimensional discrete - time maps ( see e.g. @xcite ) . among them , most simple and perfect ones are the famous bernoulli map , @xmath0 @xmath1mod@xmath2 , and the tent map , @xmath0 @xmath3 , both defined at the interval @xmath4 . almost any trajectory of both maps is chaotic , that is dense in all this interval . in computer , however , any trajectory finishes at zero after @xmath5 steps only , where @xmath6 is number of bits under use .
this contraction of the discretized phase space , from total @xmath7 points to single point @xmath8 , happens because the maps are non - invertible , i.e. relation between @xmath9 and @xmath10 is not an one - to - one correspondence . but a suitable slight distortion can make a discretized map invertible . evidently , any such map is nothing but a permutation of @xmath7 states ( @xmath11 @xmath12/n$ ] ) .
in particular , the invertible discrete versions of the bernoulli map describe the mersenne digital auto - generators of pseudo - random 0 - 1-sequences ( see e.g. @xcite ) . for example.
Please generate the next two sentences of the article | , the mersenne map in fig.1 represents transitions between 16 states of a particular `` toy '' 4-bit mersenne generator ( @xmath13 ) .
the general formula of such maps is @xmath14 where @xmath15 , @xmath16 , and any of @xmath17 , @xmath18 , equals to either zero or unit , @xmath19 ( hence this is class of @xmath20 different maps ) . to see corresponding unitary evolution matrix |
5,332 | Suppose that you have an abstract for a scientific paper: there is a growing interest in the relation between bose - einstein condensation ( bec ) and superfluidity .
a bose system confined in random media such as porous glass is suitable for studying this relation because bec and superfluidity can be suppressed and controlled in such a disordered environment .
however , it is not clear how this relation is affected by disorder and there are few theoretical studies that can be quantitatively tested by experiment . in this work ,
we develop the dilute bose gas model with a random potential that takes into account the pore size dependence of porous glass .
then we compare our model with the measured low - temperature specific heat , condensate density , and the superfluid density of @xmath0he in vycor glass .
this comparison uses no free parameters .
we predict phenomena at low temperatures that have not yet been observed .
first , the random potential causes a @xmath1-linear specific heat instead of the @xmath2 dependence that is usually caused by phonons .
second , the bec can remain even when the superfluidity disappears at low densities .
and third , the system makes a reentrant transition at low densities ; that is , the superfluid phase changes to the normal phase again as the temperature is reduced .
this reentrant transition is more likely to be observed when the strength of the random potential is increased . .
And you have already written the first three sentences of the full article: bose - einstein condensation ( bec ) and superfluidity of liquid @xmath0he in random environments including aerogel and vycor glass are active problems in quantum fluid research . in particular , finding out how spatial confinement affects the bose fluid has stimulated both experimental and theoretical studies . below the @xmath3 temperature of 2.17 k ,
liquid @xmath0he enters the superfluid state and behaves as though it has no viscosity .
superfluidity is a macroscopic quantum phenomenon as well as superconductivity , and understanding both have been one of the major goals of quantum statistical physics ..
Please generate the next two sentences of the article | the various observations of superfluidity was successfully explained by the phenomenological two fluid model , which is based on the idea that the system consists of an inviscid superfluid and a viscous normal fluid . on the other hand , the lambda transition had been thought to be caused by bec , which was confirmed by neutron scattering experiments . with a bec ,
a macroscopic number of particles occupies a single particle ground state and is described by a macroscopic wave function . |
5,333 | Suppose that you have an abstract for a scientific paper: i develop a kinetic mechanism to explain chain folding in polymer crystallization which is based on the competition between the formation of stems , which is due to frequent occupations of trans states along the chains in the supercooled polymer melt , and the random coil structure of the polymer chains .
setting equal the average formation time of stems of length @xmath0 with the rouse time of a piece of polymer of the same arc length @xmath1 yields a lower bound for the thickness of stems and bundles .
the estimated lamellar thickness is inversely proportional to the supercooling .
the present approach emphasizes the importance of repulsive interactions in polymer crystallization , which are expected to be responsible for the logarithmic lamellar thickening and the increase of lamellar thickness with pressure .
an expression for the growth rate for formation and deposition of stems is derived by considering the growth as a dynamic multistage process . .
And you have already written the first three sentences of the full article: the understanding of polymer crystallization and its theoretical description in the framework of polymer statistics remains a challenging problem since its discovery @xcite-@xcite .
the classical theories of polymer crystallization @xcite-@xcite ( see also @xcite-@xcite and citations therein ) are based on the nucleation theories developed for low molecular weight systems .
the lamellar thickness is identified ad hoc with the critical size of nuclei , and is not related with the key features of polymers in melts and solutions . despite enormous interest in polymer crystallization over many decades , the molecular mechanism of polymer crystallization is not understood , and a polymer statistics related description is not available ..
Please generate the next two sentences of the article | a review of the research in the field of polymer crystallization in the eighties can be found in @xcite .
many important specific features of polymer crystallization were established in the recent research in the field , which includes experimental work @xcite-@xcite , computer simulations @xcite-@xcite , and theoretical studies @xcite-@xcite ( and citations therein ) . |
5,334 | Suppose that you have an abstract for a scientific paper: we study associative memory of an oscillator neural network with distributed native frequencies .
the model is based on the use of the hebb learning rule with random patterns ( @xmath0 ) , and the distribution function of native frequencies is assumed to be symmetric with respect to its average .
although the system with an extensive number of stored patterns is not allowed to get entirely synchronized , long time behaviors of the macroscopic order parameters describing partial synchronization phenomena can be obtained by discarding the contribution from the desynchronized part of the system .
the oscillator network is shown to work as associative memory accompanied by synchronized oscillations . a phase diagram representing properties of memory retrieval
is presented in terms of the parameters characterizing the native frequency distribution .
our analytical calculations based on the self - consistent signal - to - noise analysis are shown to be in excellent agreement with numerical simulations , confirming the validity of our theoretical treatment . .
And you have already written the first three sentences of the full article: most of the theoretical models for associative memory of neural networks as typified by the hopfield model @xcite have been based on the idea of rate coding , which assumes that information is coded in the firing rate of a neuron at a particular time . on the other hand
, some experimental results on the visual cortex have been suggesting the possibility of another scheme of information coding , that is , the concept of temporal coding which assumes that information is coded in the relative timing of the firing pulses @xcite . stimulated by these experimental findings , studies of the temporal coding are becoming an active area of theoretical brain researches . recently , there have been an increasing number of papers reporting neurophysiological experimental findings of synchronization phenomena of neurons in animal s brain @xcite .
synchronized firings of neurons can be considered to play a key role in certain types of information processing such as the binding problem @xcite . in order to get insights into basic properties of the scheme of the temporal coding it will be necessary to study neural network models based on neurons that can be expressed by such nonlinear oscillators as limit - cycle type and integrate - and - fire type oscillators ..
Please generate the next two sentences of the article | indeed , a network of integrate - and - fire neurons , where one can be directly concerned with the spike timing of neurons , is one of such models and was previously studied @xcite to confirm its functioning as associative memory accompanied by synchronized firings
. the simplest theoretical model of synchronization of coupled oscillators will be the case of a system of phase oscillators of kuramoto et al . |
5,335 | Suppose that you have an abstract for a scientific paper: we consider the wavelet transform of a finite , rooted , node - ranked , @xmath0-way tree , focusing on the case of binary ( @xmath1 ) trees .
we study a haar wavelet transform on this tree .
wavelet transforms allow for multiresolution analysis through translation and dilation of a wavelet function .
we explore how this works in our tree context .
* keywords : * haar wavelet transform ; binary tree ; ultrametric topology ; p - adic numbers ; hierarchical clustering ; data mining ; local field ; abelian group . .
And you have already written the first three sentences of the full article: in a companion paper , which we will refer to as paper i ( `` the haar wavelet transform of a dendrogram '' ) , a new transform is applied to a hierarchical clustering .
various examples are given of uses of this transform , prior to applying the inverse transform . in this paper
, we look at linkages with other ways of understanding the wavelet transform , with the classical dmarche described in appendix 1 . our aim is to understand the wavelet transform when applied to hierarchical clustering dendrograms ( where notation and expression as ultrametric topology are summarized in appendix 2 ) ..
Please generate the next two sentences of the article | after all , both the wavelet transform and hiearchical clustering aspire to multiresolution or multiscale analysis .
the natural question is then : how do they differ and are there different aspects that they bring to the data analysis task ? |
5,336 | Suppose that you have an abstract for a scientific paper: by introducing the thermo entangled state representation , we convert the calculation of wigner function ( wf ) of density operator to an overlap between `` two pure '' states in a two - mode enlarged fock space .
furthermore , we derive a new wf evolution formula of any initial state in self - kerr medium with photon loss and find that the photon number distribution for any initial state is independent of the coupling factor with kerr medium , where the number state is not affected by the kerr nonlinearity and evolves into a density operator of binomial distribution .
* keywords : * wigner function , kerr medium , entangled state representation .
And you have already written the first three sentences of the full article: nonclassicality of optical fields has been a topic of great interest in quantum optics and quantum information processing @xcite , which is usually associated with quantum interference and entanglement .
the phase space wigner function ( wf ) @xcite of quantum states of light is a powerful tool for investigating such nonclassical effects .
the wf was first introduced by wigner in 1932 to calculate quantum corrections to a classical distribution function of a quantum - mechanical system ..
Please generate the next two sentences of the article | the partial negativity of the wf is indeed a good indication of the highly nonclassical character of the state @xcite and monitors a decoherence process of a quantum state , e. g. the excited coherent state in both photon - loss and thermal channels @xcite , the single - photon subtracted squeezed vacuum state in both amplitude decay and phase damping channels @xcite , and so on r5,r6,r7,r8,r8a .
nonlinear interaction of light in a medium provides a very useful framework to study various nonclassical properties of quantum states of radiation . |
5,337 | Suppose that you have an abstract for a scientific paper: potential games form a class of non - cooperative games where unilateral improvement dynamics are guaranteed to converge in many practical cases .
the potential game approach has been applied to a wide range of wireless network problems , particularly to a variety of channel assignment problems . in this paper ,
the properties of potential games are introduced , and games in wireless networks that have been proven to be potential games are comprehensively discussed .
potential game , game theory , radio resource management , channel assignment , transmission power control .
And you have already written the first three sentences of the full article: the broadcast nature of wireless transmissions causes co - channel interference and channel contention , which can be viewed as interactions among transceivers .
interactions among multiple decision makers can be formulated and analyzed using a branch of applied mathematics called game theory @xcite .
game - theoretic approaches have been applied to a wide range of wireless communication technologies , including transmission power control for code division multiple access ( cdma ) cellular systems @xcite and cognitive radios @xcite . for a summary of game - theoretic approaches to wireless networks ,.
Please generate the next two sentences of the article | we refer the interested reader to @xcite .
application - specific surveys of cognitive radios and sensor networks can be found in @xcite . in this paper , we focus on potential games @xcite , which form a class of strategic form games with the following desirable properties : * the existence of a nash equilibrium in potential games is guaranteed in many practical situations @xcite ( theorems [ th : existence_finite ] and [ th : existence_infinite ] in this paper ) , but is not guaranteed for general strategic form games . |
5,338 | Suppose that you have an abstract for a scientific paper: the effects of bond randomness on the phase diagram and critical behavior of the square lattice ferromagnetic blume - capel model are discussed .
the system is studied in both the pure and disordered versions by the same efficient two - stage wang - landau method for many values of the crystal field , restricted here in the second - order phase transition regime of the pure model . for the random - bond version
several disorder strengths are considered .
we present phase diagram points of both pure and random versions and for a particular disorder strength we locate the emergence of the enhancement of ferromagnetic order observed in an earlier study in the ex - first - order regime .
the critical properties of the pure model are contrasted and compared to those of the random model .
accepting , for the weak random version , the assumption of the double logarithmic scenario for the specific heat we attempt to estimate the range of universality between the pure and random - bond models .
the behavior of the strong disorder regime is also discussed and a rather complex and yet not fully understood behavior is observed .
it is pointed out that this complexity is related to the ground - state structure of the random - bond version . .
And you have already written the first three sentences of the full article: the effect of quenched randomness on the equilibrium and dynamic properties of macroscopic systems is a subject of great theoretical and practical interest .
it is well known that quenched bond randomness may produce drastic changes on phase transitions depending on the type of the transition @xcite .
thus , symmetry - breaking first - order transitions are converted to second - order phase transitions by infinitesimal bond randomness for spatial dimensionality @xmath0 @xcite and by bond randomness beyond a threshold strength in @xmath1 @xcite , as indicated by general arguments @xcite and in some cases by rigorous mathematical work @xcite ..
Please generate the next two sentences of the article | in particular , this rounding effect of first - order transitions has now been rigorously established in a unified way in low dimensions ( @xmath2 ) including a large variety of types of randomness in classical and quantum spin systems @xcite .
historically , the effects of disorder on phase transitions have been studied in two extreme cases , i.e. in the limits of weak and strong ( near the percolation point ) disorder . |
5,339 | Suppose that you have an abstract for a scientific paper: we extend a previous landau - gauge study of subtractive renormalization of the fermion propagator dyson - schwinger equation ( dse ) in strong - coupling , quenched qed@xmath0 to _ arbitrary _ covariant gauges .
we use the fermion - photon proper vertex proposed by curtis and pennington with an additional correction term included to compensate for the small gauge - dependence induced by the ultraviolet regulator .
we discuss the chiral limit and the onset of dynamical chiral symmetry breaking in the presence of nonperturbative renormalization .
we extract the critical coupling in several different gauges and find evidence of a small residual gauge - dependence in this quantity . .
And you have already written the first three sentences of the full article: strong coupling qed@xmath0 has been studied for some time within the dyson - schwinger equation ( dse ) formalism both for its intrinsic interest and also as the basis for abelianized models of nonperturbative phenomena in technicolor theories and qcd . for recent reviews of dyson - schwinger equations and their application and numerous references
see for example refs .
the usual approach is to write the dse for the fermion propagator or self - energy , possibly including equations for the photon vacuum polarization or the fermion - photon proper vertex . in a recent study.
Please generate the next two sentences of the article | @xcite it was shown for the first time how to implement nonperturbative renormalization in a numerical way within the dse formalism . in that work
the calculations were carried out in quenched approximation in landau gauge . here |
5,340 | Suppose that you have an abstract for a scientific paper: studies related to _ crowds _ of pedestrians , both those of theoretical nature and application oriented ones , have generally focused on either the _ analysis _ or the _ synthesis _ of the phenomena related to the interplay between individual pedestrians , each characterised by goals , preferences and potentially relevant relationships with others , and the environment in which they are situated . the cases in which these activities have been systematically integrated for a mutual benefit are still very few compared to the corpus of crowd related literature .
this paper presents a case study of an integrated approach to the definition of an innovative model for pedestrian and crowd simulation ( on the side of synthesis ) that was actually motivated and supported by the analyses of empirical data acquired from both experimental settings and observations in real world scenarios .
in particular , we will introduce a model for the adaptive behaviour of pedestrians that are also members of groups , that strive to maintain their cohesion even in difficult ( e.g. high density ) situations .
the paper will show how the synthesis phase also provided inputs to the analysis of empirical data , in a virtuous circle .
crowd analysis , crowd synthesis , agent based modelling and simulation , groups .
And you have already written the first three sentences of the full article: the modelling and simulation of pedestrians and crowds is a consolidated and successful application of research results in the more general area of computer simulation of complex systems .
it is an intrinsically interdisciplinary effort , with relevant contributions from disciplines ranging from physics and applied mathematics to computer science , often influenced by ( and sometimes in collaboration with ) anthropological , psychological , sociological studies and the humanities in general .
the level of maturity of these approaches was sufficient to lead to the design and development of commercial software packages , offering useful and advanced functionalities to the end user ( e.g. cad integration , cad - like functionalities , advanced visualisation and analysis tools ) in addition to a simulation engine . nonetheless , as testified by a recent survey of the field by @xcite and by a report commissioned by the cabinet office by @xcite , there is still much room for innovations in models improving their performances both in terms of _ effectiveness _ in modelling pedestrians and crowd phenomena , in terms of _ expressiveness _ of the models ( i.e. simplifying the modelling activity or introducing the possibility of representing phenomena that were still not considered by existing approaches ) , and in terms of _ efficiency _ of the simulation tools ..
Please generate the next two sentences of the article | in addition to the above directions , we want to emphasise the fact that one of the sometimes overlooked aspects of a proper simulation project is related to the _ calibration _ and _ validation _ of the results of tools related to the _ synthesis _ of the pedestrians and crowd behaviour in the considered scenario .
these phases are essentially related to the availability of proper empirical data about or , at least , relevant to , the considered scenario ranging from the pedestrian demand ( i.e. an origin destination matrix ) , preferences among different alternative movement choices ( e.g. percentage of persons employing stairs , escalators and elevators in a multiple level scenario ) , but also the average waiting times at service points ( i.e. queues ) , the average time required to cover certain paths , the spatial distribution of pedestrians in specific environmental conditions that is required to evaluate the so called `` level of service '' associated to portions of the environment as defined by @xcite . |
5,341 | Suppose that you have an abstract for a scientific paper: forthcoming advances in direct gravitational wave detection from kilohertz to nanohertz frequencies have unique capabilities to detect signatures from or set meaningful constraints on a wide range of new cosmological phenomena and new fundamental physics .
a brief survey is presented of the post - inflationary gravitational radiation backgrounds predicted in cosmologies that include intense new classical sources such as first - order phase transitions , late - ending inflation , and dynamically active mesoscopic extra dimensions .
lisa will provide the most sensitive direct probes of such phenomena near tev energies or terascale .
lisa will also deeply probe the broadband background , and possibly bursts , from loops of cosmic superstrings predicted to form in current models of brane inflation .
address= astronomy and physics departments , university of washington , seattle , washington 98195 - 1580 .
And you have already written the first three sentences of the full article: in recent years , cosmology has converged on a `` concordance '' model that continues to meet with remarkable success wherever new observational tests are introduced .
the direct data span a large dynamic range of structural scales , including power spectrum probes over about a factor of @xmath0 in linear comoving scale .
the microwave background spectrum and the products of cosmological nucleosynthesis confirm basic model assumptions and microphysics back to the first fraction of a second of the big bang ..
Please generate the next two sentences of the article | an important part of the standard scenario is inflation .
the generic inflationary predictions of near global flatness and nearly scale - invariant , gaussian fluctuations are well confirmed by the data . |
5,342 | Suppose that you have an abstract for a scientific paper: we extract information on the fluxes of be and cno neutrinos directly from solar neutrino experiments , with minimal assumptions about solar models .
next we compare these results with solar models , both standard and non standard ones .
finally we discuss the expectations for borexino , both in the case of standard and non standard neutrinos . .
And you have already written the first three sentences of the full article: the principal aim of this paper is to extract information on the fluxes of be and cno neutrinos directly from solar neutrino experiments , with minimal assumptions about solar models . in this respect
, we will update previous results @xcite and try to elucidate the role of cno neutrinos .
we will see that experimental data are more and more against the hypothesis of standard neutrinos ( without mass , mixing , magnetic moments ... ) ..
Please generate the next two sentences of the article | next we will compare these informations with solar models , both standard and non standard ones .
clearly , low ( smaller than standard ) central temperature models are ruled out , essentially because they can not reproduce the experimental data available on both be and b neutrinos . |
5,343 | Suppose that you have an abstract for a scientific paper: we show the natural relation between the wigner hamiltonian and the conformal hamiltonian . it is presented a model in ( super)conformal quantum mechanics with ( super)conformal symmetry in the wigner - heisenberg algebra picture @xmath0= i(1+c{\bf p})$ ] ( @xmath1 being the parity operator ) . in this context , the energy spectrum , the casimir operator , creation and annihilation operators are defined .
this superconformal hamiltonian is similar to the super - hamiltonian of the calogero model and it is also an extension of the super - hamiltonian for the dirac oscillator . where @xmath2,\ ] ] so that the parity operator is conserved , i.e. , @xmath3 = 0.$ ] when one introduces the following operators @xmath4 it can be shown that these operators together with the conformal quantum mechanics operators @xmath5 and @xmath6 @xmath7 satisfy the deformed superalgebra @xmath8 when we fix @xmath9 or @xmath10 .
] , viz . , @xmath11 & = & -2\imath \mathcal{h } , \nonumber\\ \left[{\mathcal{h}},k \right ] & = & -\imath d , \nonumber\\ \left[k , d \right ] & = & 2 \imath k,\nonumber\\ \{q_{c } , q_{c}^\dagger \ } & = & 2 \mathcal{h},\nonumber \\
\{q_{c } , s^\dagger\ } & = & -\imath d - \frac{1}{2 } b(1 + c { \bf p } ) + \sqrt{g } , \nonumber\\ \{q_{c}^\dagger , s \ } & = & + \imath d - \frac{1}{2 } b(1 + c { \bf p } ) + \sqrt{g } , \nonumber\\ \left[q_{c}^{\dagger } , d \right ] & = & -\imath q_{c}^\dagger,\nonumber\\ \left[q_{c}^\dagger , k \right ] & = & s^\dagger , \nonumber\\ \left[q_{c}^\dagger , b \right ] & = & 2 q_{c}^\dagger , \nonumber\\ \left[q_{c } , k \right ] & = & -s,\nonumber\\ \left[q_{c } , b \right ] & = & -2 q_{c } , \nonumber\\ \left[q_{c } , d \right ] & = & -\imath q_{c } , \nonumber\\ \left [ \mathcal{h } , s \right ] & = & q_{c } , \hspace{2 cm } \left [ \mathcal{h } , s^\dagger \right ] = -q_{c}^\dagger , \nonumber\\ \left [ b , s^\dagger \right ] & = & -2 s^\dagger , \hspace{2 cm } \left[b , s \right ] = 2s , \nonumber\\ \left[d , s \right ] & = & -\imath s ,....
And you have already written the first three sentences of the full article: [ [ section ] ] in this work , we have analyzed the connection between the conformal quantum mechanics @xcite and the wigner - heisenberg algebra @xcite . with an appropriate relationship between the coupling constant @xmath64 and real constant @xmath63
one can identify the wigner hamiltonian with the conformal hamiltonian @xmath14 .
the important result is that the introduction of the wigner - heisenberg algebra in the conformal quantum mechanics is still consistent with the conformal symmetry ..
Please generate the next two sentences of the article | the spectrum for the casimir operator , the hamiltonian @xmath14 and the ladder operators depend on the parity operator .
we also investigated the supersymmetrization of this model , in that case we obtain a new spectra for the supersymmetric and conformal hamiltonian of the calogero interaction s type . in this case the spectrum for the super - casimir operator and the superhamiltonian depend also on the parity operator . |
5,344 | Suppose that you have an abstract for a scientific paper: the offline problem of transmission completion time minimization for an energy harvesting transmitter under fading is extended to allow packet arrivals during transmission .
a method for computing an optimal power and rate allocation ( i.e. , an optimal offline schedule ) is developed and studied .
transmission of packets over a fading channel under energy harvesting energy harvesting , completion time , offline schedule , packet scheduling , causality constraints , energy constraint , unconstrained problem , sumt , sequential optimization , complexity . .
And you have already written the first three sentences of the full article: energy harvesting communication systems involve transmitters being powered by environmental sources such as solar , vibration , and thermal effects , either alone or as supplement to the power drawn from a grid .
the ability to supply the energy storage units from environmental sources can be very useful in distributed systems such as wireless sensor networks , and m2 m networks .
recent developments in ambient energy harvesting technologies have already resulted in the practical implementation of such systems @xcite ..
Please generate the next two sentences of the article | dependence on a variable energy source ( as opposed to a constant supply of power ) poses interesting new challenges for the transmission of information .
optimal adaptation of transmission rate has been analyzed under various problem formulations @xcite-@xcite . in @xcite , |
5,345 | Suppose that you have an abstract for a scientific paper: we report superconducting properties of agsnse@xmath0 which is a conventional type - ii superconductor in the very dirty limit due to intrinsically strong electron scatterings .
while this material is an isotropic three - dimensional ( 3d ) superconductor with a not - so - short coherence length where strong vortex fluctuations are _ not _ expected , we found that the magnetic - field - induced resistive transition at fixed temperatures becomes increasingly broader toward zero temperature and , surprisingly , that this broadened transition is taking place largely _ above _ the upper critical field determined thermodynamically from the specific heat .
this result points to the existence of an anomalous metallic state possibly caused by quantum phase fluctuations in a strongly - disordered 3d superconductor . .
And you have already written the first three sentences of the full article: the interplay between disorder and superconductivity has attracted sustained interest over the past few decades . in bcs superconductors , according to anderson s theorem , @xcite the superconducting critical temperature @xmath1 and the energy gap @xmath2 remain unaffected by the presence of weak disorder , although in unconventional superconductors both @xmath1 and @xmath2 are strongly suppressed with weak disorder .
@xcite in the strongly disordered regime , things become interesting even in bcs superconductors : in two - dimensional ( 2d ) systems , strong disorder leads to a universal superconductor - to - insulator transition at a critical sheet resistance of @xmath3 ; @xcite furthermore , it has been found that , as @xmath4 tends to zero , there emerges a broad range of magnetic field where the resistivity remains finite but is much smaller than the normal - state value , which arguably signifies the importance of quantum phase fluctuations .
@xcite in three - dimensional ( 3d ) systems , strong disorder leads to a disruption of the global superconducting coherence through reductions in both the superfluid density @xmath5 and pairing interactions , which results in the superconducting order parameter to spatially fluctuate and gives rise to anomalous electronic states near the superconductor - to - metal transition ..
Please generate the next two sentences of the article | @xcite experimentally , while the 2d systems have been actively studied in the past , @xcite the role of strong disorder in 3d superconductors is just beginning to be addressed with a modern viewpoint , @xcite which naturally calls for explorations of suitable materials for such a study . in this paper , we report that agsnse@xmath6 , which is a low-@xmath7 conventional superconductor having a cubic structure , offers an ideal playground for studying the effects of strong disorder in 3d superconductors .
we show that one can synthesize high - quality samples of agsnse@xmath6 presenting a very sharp superconducting transition , which indicates that morphologically the system is homogeneous ; nonetheless , strong electron scatterings that are intrinsic to this system lead to an extremely type - ii superconductivity with the ginzburg - landau parameter @xmath8 of as large as 55 . |
5,346 | Suppose that you have an abstract for a scientific paper: this paper presents numerical results for the two - dimensional isotropic kuramoto - sivashinsky equation ( kse ) with an additional nonlinear term and a single independent parameter .
surfaces generated by this equation exhibit a certain dependence of the average saturated roughness on the system size that indicates power - law shape of the surface spectrum for small wave numbers .
this leads to a conclusion that although cellular surface patterns of definite scale dominate in the range of short distances , there are also scale - free long - range height variations present in the large systems .
the dependence of the spectral exponent on the equation parameter gives some insight into the scaling behavior for large systems . .
And you have already written the first three sentences of the full article: the kuramoto - sivashinsky equation ( kse ) in its dimensionless form for some field @xmath0 can be written as @xcite @xmath1 this equation stands as a paradigmatic model for chaotic spatially extended systems and can be used to study the connections between chaotic dynamics at small scales and apparent stochastic behavior at large scales .
it is an example of an extended , deterministic dynamical system that exhibits complex spatio - temporal phenomena .
the kse has been derived for the purpose of describing the intrinsic instabilities in laminar flame fronts @xcite and phase - dynamics in reaction - diffusion systems @xcite ..
Please generate the next two sentences of the article | the equation ( [ eq : kse ] ) in one- and two - dimensional cases has been a subject of active research for about three decades , and its scaling properties have even been an object of some controversy @xcite .
this paper presents some results obtained from a less researched _ generalized _ version of kse . |
5,347 | Suppose that you have an abstract for a scientific paper: we consider the limiting case for orbital stability of the companions to hr 8799 .
this case is only consistent with ages for the system of @xmath0 100 myr , not with the 1 gyr age proposed from astroseismology .
the discrepancy probably arises because the inclination of the star is smaller than assumed in analyzing the astroseismology data .
given this young age , the best estimates of the companion masses place them by a small margin on the planet side of the division between planets and brown dwarfs . .
And you have already written the first three sentences of the full article: hr 8799 is a late a / early f star located at 39.4 pc , with t@xmath1 @xmath0 7350k , m@xmath2 = 1.5 m@xmath3 and a @xmath4 bootis - like pattern of surface metallicity .
the star has received a very high level of attention since the imaging of three massive substellar objects in large radius orbits around it ( marois et al .
hr 8799 and fomalhaut ( kalas et al ..
Please generate the next two sentences of the article | 2008 ) are the only two firm examples of systems with separations @xmath5 50 au between the star and planetary - mass companions .
both stars also have luminous planetary debris disks that can provide further insight to the outer structures of their planetary systems ( e.g. , stapelfeldt et al . |
5,348 | Suppose that you have an abstract for a scientific paper: a systematic investigation of dust emission associated with the ionized gas has so far been performed only in our galaxy and for wavelengths longer than 60 @xmath0 .
newly available spitzer data now offer the opportunity to carry out a similar analysis in the large magellanic cloud ( lmc ) . by cross - correlating spitzer sage ( surveying the agents of a galaxy s evolution ) data with the atca /
parkes hi 21-cm data , the nanten @xmath1 ( j=1 - 0 ) data , and both the shassa h@xmath2 and the parkes 6-cm data , we investigate the physical properties of dust associated with the different phases of the gas ( atomic , molecular and ionized ) .
in particular , we study the presence and nature of dust from 3.6 to 160 @xmath0 and for various regimes of the ionized gas , spanning emission measures ( em ) from @xmath3 1 pc @xmath4 ( diffuse component ) to @xmath3 10@xmath5 pc @xmath4 ( hii regions ) . using a dust emission model , and testing our results with several radiation field spectra ,
we show that dust in the ionized gas is warmer than dust associated with other phases ( atomic and molecular ) .
we also find a decrease of the polycyclic aromatic hydrocarbons ( pah ) relative abundance with respect to big grains ( bgs ) , as well as an increase of the near infrared ( nir ) continuum .
these three results ( e.g. warmer temperature , decrease of pah abundance and increase of the nir continuum ) are found consistently for all regimes of the ionized gas . on the contrary
, the molecular phase appears to provide favorable conditions for the survival of pahs .
furthermore , the very small grain ( vsg ) relative abundance tends to increase in the ionized phase , especially in bright hii regions .
last but not least , our analysis shows that the emissivity of dust associated with the ionized gas is lower in the lmc than in our galaxy , and that this difference is not accounted for by the lower metallicity of the lmc . .
And you have already written the first three sentences of the full article: detecting dust emission associated with the diffuse ionized phase is a complex task due to two main competing factors .
first of all , large grains are expected to be selectively destroyed in the warm ionized medium ( wim ) due to the passage of multiple shock fronts which would reduce their emission .
in addition , along most line of sights ( los ) , the diffuse ionized gas is likely mixed with the other phases of the gas ( atomic and molecular ) , and its contribution is not expected to be dominant at any latitude . because of these difficulties.
Please generate the next two sentences of the article | , contradictory results concerning the presence of dust in the wim have been reported in the literature .
@xcite , looking at the high galactic latitude residuals of the ir / hi correlation between 100 and 1000 @xmath0 , claim a statistical detection . |
5,349 | Suppose that you have an abstract for a scientific paper: turbulence theory is usually concerned with the statistical moments of the velocity and its fluctuations .
one could also analyze the implicit probability distributions .
this is the purview of information theory .
here we use information theory , specifically the conditional entropy , to analyze ( quasi-)2d turbulence .
we recast richardson s eddy hypothesis " that large eddies break up into small eddies in time using the language of information theory .
in addition to confirming richardson s idea , we find that self - similarity and turbulent length scales reappear naturally .
not surprisingly , we also find that the direction of information transfer is the same as the direction of the cascade itself .
consequently , intermittency may be considered a necessary companion to all turbulent flows . .
And you have already written the first three sentences of the full article: the unpredictability of turbulence makes a deterministic analysis of the instantaneous velocity field not only impractical , but very nearly impossible .
researchers have instead studied the statistical properties of turbulence , which necessarily involves the probabilities of velocities and their fluctuations @xcite .
although information theory is the natural language for treating these probability distributions @xcite , there have been few studies that make use of it . instead.
Please generate the next two sentences of the article | , the focus has often been on the moments @xcite . in wall - bounded flows , for example
, considerable effort has been directed towards determining the mean velocity profile as a universal function of distance from the wall @xcite . in other situations , |
5,350 | Suppose that you have an abstract for a scientific paper: we applied our recently proposed empirical formula , a formula quite successful in describing essential trends of the lowest excitation energies of the natural parity even multipole states , to the lowest excitation energies of the natural parity odd multipole states in even - even nuclei throughout the entire periodic table .
even though the systematic behavior of the lowest excitation energies of odd multipole states is quite different from those of even multipole states , we have shown that the same empirical formula also holds reasonably well for the odd multipole states with the exception of a few certain instances . empirical formula ;
lowest excitation energies of natural parity odd multipole states ; valence nucleon numbers + 21.10.re ; 23.20.lv nuclear physics can be explained from two standpoints .
one is the portrait description where the excited states of an individual nucleus are studied in depth .
the traditional nuclear structure models , which have contributed significantly to the development of nuclear physics , belong to this category .
the other is the landscape description where some particular nuclear properties are examined in terms of simple nuclear variables over the wide span of the chart of nuclides .
a well - known example of a landscape description is the weizscker s semi - empirical mass formula first proposed in the early 1930 s @xcite .
it can reproduce the binding energy of the ground state of nuclei very accurately throughout the entire chart of nuclides in terms of the mass number @xmath0 and the atomic number @xmath1 with just a few fitted parameters .
however , for a very long time , no expression of a similar sort has been available for the properties of excited states in nuclei until very recently when we proposed a simple empirical formula for the lowest excitation energies @xmath2 of the natural parity even multipole states in even - even nuclei @xcite .
this formula , which depends only on the mass number @xmath0 , the valence proton number....
And you have already written the first three sentences of the full article: this work was supported by the korea science and engineering foundation(kosef ) grant funded by the korea government(mest ) ( 2006 - 8 - 0083 ) .
999 c. f. von weizscker , z. phys .
* 96 * ( 1935 ) 431 ..
Please generate the next two sentences of the article | e. ha and d. cha , j. korean phys
* 50 * ( 2007 ) 1172 . |
5,351 | Suppose that you have an abstract for a scientific paper: we investigate the dynamics of a simple epidemiological model for the invasion by a pathogen strain of a population where another strain circulates .
we assume that reinfection by the same strain is possible but occurs at a reduced rate due to acquired immunity .
the rate of reinfection by a distinct strain is also reduced due to cross - immunity .
individual based simulations of this model on a ` small - world ' network show that the host contact network structure significantly affects the outcome of such an invasion , and as a consequence will affect the patterns of pathogen evolution .
in particular , host populations interacting through a small - world network of contacts support lower prevalence of infection than well - mixed populations , and the region in parameter space for which an invading strain can become endemic and coexist with the circulating strain is smaller , reducing the potential to accommodate pathogen diversity .
we discuss the underlying mechanisms for the reported effects , and we propose an effective mean - field model to account for the contact structure of the host population in small - world networks .
keywords : pathogen diversity , reinfection threshold , spatial structure , complex networks .
And you have already written the first three sentences of the full article: pathogens that diversify and evolve over relatively short time scales are associated with specific features of infectious disease epidemiology .
epidemics of acute respiratory infection occuring each winter in temperate climates are caused in general by influenza ( hay 2001 ) and respiratory syncytial viruses ( cane 2001 ) .
rotaviruses ( iturriza - gmara 2004 ) are the single most common cause of acute infantile gastroenteritis throughout the world ..
Please generate the next two sentences of the article | these viruses undergo antigenic drift and both influenza a and rotaviruses undergo major antigenic shifts when a new virus is introduced into the human population through zoonotic transmission .
the dynamics of the epidemic is closely related to the antigenic structure and evolution of the viral population . |
5,352 | Suppose that you have an abstract for a scientific paper: we study the energy dependent photon variability from a thermal comptonizing plasma that is oscillating at khz frequencies . in particular , we solve the linearised time dependent kompaneets equation and consider the oscillatory perturbation to be either in the soft photon source or in the heating rate of the plasma . for each case , we self consistently consider the energy balance of the plasma and the soft photon source .
the model incorporates the possibility of a fraction of the comptonized photons impinging back into the soft photon source .
we find that when the oscillation is due to the soft photon source , the variation of the fractional root mean sqaure ( r.m.s ) is nearly constant with energy and the time - lags are hard .
however , for the case when the oscillation is due to variation in the heating rate of the corona , and when a significant fraction of the photons impinge back into the soft photon source , the r.m.s increases with energy and the time lags are soft . as an example , we compare the results with the @xmath0 hz oscillation observed on march 3 , 1996 for 4u 1608 - 52 and show that both the observed soft time - lags as well as the r.m.s versus energy can be well described by such a model where the size of the comptonizing plasma is @xmath1 km .
thus , modelling of the time lags as due to comptonization delays , can provide tight constraints on the size and geometry of the system .
detailed analysis would require well constrained spectral parameters . [ firstpage ] stars : neutron x - rays : binaries x - rays : individual : 4u 160852 radiation mechanisms : thermal .
And you have already written the first three sentences of the full article: x - ray binaries harbour compact objects and their x - ray luminosity is believed to be generated due to an accretion disk formed by material accreted from a companion star .
the x - ray emission is known to vary on a wide range of timescales .
it was after the launch of the _ rossi x - ray timing explorer _.
Please generate the next two sentences of the article | ( rxte ) satellite , that millisecond variability was detected in several sources ( for reviews see for e.g. * ? ? ?
* ; * ? ? ? |
5,353 | Suppose that you have an abstract for a scientific paper: the distribution of the spin of the nucleon among its constituents can be parametrized in the form of polarized parton distribution functions for quarks and gluons . using all available data on the polarized structure function @xmath0 , we determine these distributions both at leading and next to leading order in perturbation theory .
we suggest three different , equally possible scenarios for the polarized gluon distribution , which is found to be only loosely constrained by current experimental data . we examine various possibilities of measuring polarized parton distributions at future experiments .
20.5 cm dtp/95/82 + december 1995 + 1.cm * polarized parton distributions in the nucleon * 1.cm t. gehrmann and w.j . stirling .4 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: understanding the spin structure of the nucleon is one of the most important questions in strong interaction physics today .
there has been renewed interest in recent years , largely as a result of a series of high precision polarized deep inelastic scattering experiments .
so far , the bulk of the information comes from measurements of the spin - dependent structure function @xmath0 . from such measurements ,.
Please generate the next two sentences of the article | spin - dependent parton distributions can be extracted and compared with theoretical models , or used to make predictions for future experiments .
several theoretical issues have received particular attention : the predictions of various sum rules and the measurement of @xmath1 , the magnitude of the polarized gluon distribution , and the behaviour of the polarized parton distributions at small @xmath2 . in a previous study @xcite |
5,354 | Suppose that you have an abstract for a scientific paper: we report on a computer simulation and integral equation study of a simple model of patchy spheres , each of whose surfaces is decorated with two opposite attractive caps , as a function of the fraction @xmath0 of covered attractive surface .
the simple model explored the two - patch kern - frenkel model interpolates between a square - well and a hard - sphere potential on changing the coverage @xmath0 . we show that integral equation theory provides quantitative predictions in the entire explored region of temperatures and densities from the square - well limit @xmath1 down to @xmath2 . for smaller @xmath0 , good numerical convergence of the equations
is achieved only at temperatures larger than the gas - liquid critical point , where however integral equation theory provides a complete description of the angular dependence .
these results are contrasted with those for the one - patch case .
we investigate the remaining region of coverage via numerical simulation and show how the gas - liquid critical point moves to smaller densities and temperatures on decreasing @xmath0 .
below @xmath3 , crystallization prevents the possibility of observing the evolution of the line of critical points , providing the angular analog of the disappearance of the liquid as an equilibrium phase on decreasing the range for spherical potentials .
finally , we show that the stable ordered phase evolves on decreasing @xmath0 from a three - dimensional crystal of interconnected planes to a two - dimensional independent - planes structure to a one - dimensional fluid of chains when the one - bond - per - patch limit is eventually reached . .
And you have already written the first three sentences of the full article: spherically symmetric potentials have become a well - established paradigm of colloidal science in past decades .
@xcite this is because , at a sufficiently coarse - grained level , colloidal surface composition can be regarded as uniform with a good degree of confidence , so that relevant interactions depend only on relative distances among the particles .
recent advances in chemical particle synthesis @xcite have however challenged this view by emphasizing the fundamental role of surface colloidal heterogeneities and their detailed chemical compositions ..
Please generate the next two sentences of the article | this is particularly true for an important subclass of colloidal systems , namely proteins , where the presence of anisotropic interactions can not be neglected , even at the minimal level .
@xcite directional interactions introduce novel properties in such systems . |
5,355 | Suppose that you have an abstract for a scientific paper: we describe a technique for simultaneously classifying and estimating the redshift of quasars .
it can separate quasars from stars in arbitrary redshift ranges , estimate full posterior distribution functions for the redshift , and naturally incorporate flux uncertainties , missing data , and multi - wavelength photometry .
we build models of quasars in flux redshift space by applying the _ extreme deconvolution _ technique to estimate the underlying density . by integrating this density over redshift
one can obtain quasar flux
densities in different redshift ranges .
this approach allows for efficient , consistent , and fast classification and photometric redshift estimation .
this is achieved by combining the speed obtained by choosing simple analytical forms as the basis of our density model with the flexibility of non - parametric models through the use of many simple components with many parameters .
we show that this technique is competitive with the best photometric quasar classification techniques which are limited to fixed , broad redshift ranges and high signal - to - noise ratio data and with the best photometric redshift techniques when applied to broadband optical data .
we demonstrate that the inclusion of uv and nir data significantly improves photometric quasar
star separation and essentially resolves all of the redshift degeneracies for quasars inherent to the @xmath0 filter system , even when included data have a low signal - to - noise ratio . for quasars
spectroscopically confirmed by the _
sdss _ 84 and 97percent of the objects with _
_ uv and _ ukidss _
nir data have photometric redshifts within 0.1 and 0.3 , respectively , of the spectroscopic redshift ; this amounts to about a factor of three improvement over @xmath0-only photometric redshifts .
our code to calculate quasar probabilities and redshift probability distributions is publicly available . .
And you have already written the first three sentences of the full article: the last decade has seen the first instances of statistical studies with quasars using purely photometric samples .
examples of these include the measurement of the integrated sachs
wolfe effect @xcite and cosmic magnification bias @xcite , and studies of the clustering of quasars on large @xcite and small @xcite scales ..
Please generate the next two sentences of the article | the importance of photometrically classified quasar samples will only increase during the next decade as large new imaging surveys will uncover large samples of quasars at fainter magnitudes , with minimal spectroscopy for the faintest objects .
while efficient photometric classification is one requirement to facilitate studies of quasars without extensive spectroscopy , it has also been crucial to develop accurate methods for quasar redshift estimation based on broadband photometry . |
5,356 | Suppose that you have an abstract for a scientific paper: interplay between the spectator and participant matter in heavy - ion collisions is investigated within isospin dependent quantum molecular dynamics ( iqmd ) model in term of rapidity distribution of light charged particles .
the effect of different type and size rapidity distributions is studied in elliptical flow .
the elliptical flow patterns show important role of the nearby spectator matter on the participant zone .
this role is further explained on the basis of passing time of the spectator and expansion time of the participant zone .
the transition from the in - plane to out - of - plane is observed only when the mid - rapidity region is included in the rapidity bin , otherwise no transition occurs .
the transition energy is found to be highly sensitive towards the size of the rapidity bin , while weakly on the type of the rapidity distribution .
the theoretical results are also compared with the experimental findings and are found in good agreement . .
And you have already written the first three sentences of the full article: since last many years , investigation about the nuclear equation of state ( neos ) at the extreme conditions of density and temperature has been one of the primary driving forces in heavy ion studies at intermediate energies .
the interest in low energies , however , are for isospin effects in fusion process @xcite .
these investigations has been performed with the help of rare phenomena such as multifragmentation , collective flow , particle production as well as nuclear stopping @xcite ..
Please generate the next two sentences of the article | the relation between the nuclear eos and flow phenomena has been explored extensively in the simulations .
recently the analysis of transverse - momentum dependence of elliptical flow has also been put forwarded @xcite . |
5,357 | Suppose that you have an abstract for a scientific paper: we present measurements of the transverse momentum spectra , yield and @xmath0 systematics for @xmath1 , @xmath2 and @xmath3 in @xmath4 collisions at @xmath5 gev .
we show a dependence of the @xmath0 with event multiplicity and infer that this is consistent with a mini - jet dominated particle production mechanism .
these observations are compared to available data from @xmath6 experiments as well as to pqcd theoretical predictions . .
And you have already written the first three sentences of the full article: particles which contain strange quarks are valuable probes of the dynamics of @xmath4 collisions as constituent strange quarks are not present in the initial colliding nuclei .
the enhancement of the strange particle yield from @xmath4 collisions to heavy ion collisions has been suggested as a possible quark gluon plasma signature @xcite .
+ we report preliminary results from the 2001/2002 p+p run by the star experiment ..
Please generate the next two sentences of the article | the main focus of this paper is on presenting a high statistics measurement of @xmath1 , @xmath2 and @xmath3 at @xmath5 gev and obtaining the yield and @xmath0 for each species .
a discussion of appropriate parameterizations to the particle spectra will ensue . |
5,358 | Suppose that you have an abstract for a scientific paper: we investigate a class of models with a massless fermion and a self - interacting scalar field with the yukawa interaction between these two fields .
the models considered are formulated in two and four spacetime dimensions and possess a discrete symmetry .
we calculate the chiral condensates are calculated in the one - loop approximation .
we show that the models have a phase transitions as a function of the coupling constants . .
And you have already written the first three sentences of the full article: dynamical breaking of a symmetry can be described by a quantity known as the order parameter . in the case of a broken chiral symmetry
a commonly used order parameter is the chiral condensate which vanishes if the chiral symmetry is unbroken .
the investigation of the chiral condensate plays a crucial role in attempts to describe phase transitions related to the dynamical chiral symmetry breaking . in qcd chiral condensate.
Please generate the next two sentences of the article | is obtained by numerical studies , as a rule via lattice simulations .
this approach is usually employed in studies of the chiral condensate in the presence of external factors such as temperature , chemical potentials , magnetic field , finite size effects , etc ( see [ 1 - 3 ] and references therein ) . apart from numerical studies there is a lot of models employed for the investigation of the chiral condensate in various physical systems @xcite , @xcite . in the first paper on this subject @xcite nambu and |
5,359 | Suppose that you have an abstract for a scientific paper: we introduce a family of criteria to detect quantum non - gaussian states of a harmonic oscillator , that is , quantum states that can not be expressed as a convex mixture of gaussian states .
in particular we prove that , for convex mixtures of gaussian states , the value of the wigner function at the origin of phase space is bounded from below by a non - zero positive quantity , which is a function only of the average number of excitations ( photons ) of the state . as a consequence ,
if this bound is violated then the quantum state must be quantum non - gaussian .
we show that this criterion can be further generalized by considering additional gaussian operations on the state under examination .
we then apply these criteria to various non - gaussian states evolving in a noisy gaussian channel , proving that the bounds are violated for high values of losses , and thus also for states characterized by a positive wigner function . .
And you have already written the first three sentences of the full article: several criteria to detect non - classicality of quantum states of a harmonic oscillator have been introduced , mostly based on phase - space distributions @xcite , ordered moments @xcite , or on information - theoretic arguments @xcite . at the same time
, an ongoing research line addresses the characterization of quantum states according to their gaussian or non - gaussian character @xcite , and a question arises on whether those two different hierarchies are somehow linked each other . as a matter of fact ,
if we restrict our attention to pure states , hudson s theorem @xcite establishes that the border between gaussian and non - gaussian states coincides exactly with the one between states with positive and negative wigner functions ..
Please generate the next two sentences of the article | however , if we move to mixed states , the situation gets more involved .
attempts to extend hudson s theorem have been made , by looking at upper bounds on non - gaussianity measures for mixed states having positive wigner function @xcite . in this framework , by focusing on states with positive wigner function , one can define an additional border between states in the _ gaussian convex hull _ and those in the complementary set of _ quantum non - gaussian states _ |
5,360 | Suppose that you have an abstract for a scientific paper: it is generally difficult to experimentally distinguish magnetic multipolar orders in spin systems .
recently , it was proposed that the temperature dependence of the nuclear magnetic resonance relaxation rate @xmath0 can involve an indirect , but clear signature of the field - induced spin nematic or multipolar tomonaga - luttinger ( tl ) liquid phase [ phys .
rev .
b * 79 * , 060406(r ) ( 2009 ) ] . in this paper , we evaluate accurately the field and temperature dependence of @xmath0 in spin-@xmath1 frustrated @xmath2-@xmath3 chains combining field - theoretical techniques with numerical data .
our results demonstrate that isotherms of @xmath0 as a function of magnetic field also exhibit distinctive non - monotonic behavior in spin nematic tl liquid , in contrast with the standard tl liquid in the spin-@xmath1 heisenberg chain .
the relevance of our results to quasi one - dimensional edge - sharing cuprate magnets , such as @xmath4 , is discussed . .
And you have already written the first three sentences of the full article: one of the current topics in solid - state magnetism is multiple - spin ordering without any single - spin dipole moment.@xcite vector and scalar chiral orders and spin multipolar orders are typical examples expected to appear in real compounds .
the emergence of vector and scalar chiralities accompanies the spontaneous breakdown of parity or time - reversal symmetries and these two could be detected indirectly from parity- or time - reversal - odd observables and related quantities ( e.g. , electric polarization in multiferroics , asymmetric momentum dependence of spin structure factors , hall conductivity , etc ) . on the other hand ,
spin multipolar orders , for example , spin nematic and spin triatic orders , in spin-@xmath1 magnets can occur without breaking spatial symmetry , since they are characterized as condensation of bound multi - magnons@xcite or spin - triplet resonating valence bond state.@xcite the absence of both spin long - range order and lattice symmetry breaking makes it difficult to find them in experiments ..
Please generate the next two sentences of the article | furthermore , no clear experimental proof of the spin multipolar orders has ever been reported , because there is no established experimental method of probing spin multipolar orders .
thanks to recent theoretical studies , it has been gradually recognized that magnetic multipolar states occur in several geometrically frustrated spin-@xmath1 magnets , especially , in low dimensions . |
5,361 | Suppose that you have an abstract for a scientific paper: this essay discusses phenomenological aspects of the diffusion time dependence of the spectral dimension predicted by the causal dynamical triangulations ( cdt ) approach to quantum gravity .
the deformed form of the dispersion relation for the fields defined on the cdt space - time is reconstructed . using the _ fermi _ satellite observations of the grb 090510 source we find that the energy scale of the dimensional reduction is @xmath0 gev at ( 95 @xmath1 cl ) . by applying the deformed dispersion relation to the cosmological perturbations
it is shown that , for a scenario when the primordial perturbations are formed in the uv region , the scalar power spectrum @xmath2 where @xmath3 . here
, @xmath4 is obtained from the cdt value of the spectral dimension in the uv limit and @xmath5 is the tensor - to - scalar ratio .
we find that , the predicted deviation from the scale - invariance ( @xmath6 ) is in contradiction with the up to date _ planck _ and _ bicep2 _ results . .
And you have already written the first three sentences of the full article: the littleness of the planck length is indescribable .
the immense size the observable universe is paralyzing .
however , the geometric mean of the two characteristic values results in a tangible quantity ..
Please generate the next two sentences of the article | explicitly , @xmath7 , where the planck length @xmath8 m and the gigaparsec @xmath9 m. as we will show in the example discussed in the essay , better understanding of both the super - short and super - large scales can be gained thanks to this property .
so , how does it work ? |
5,362 | Suppose that you have an abstract for a scientific paper: we investigate the physical properties of molecular hydrogen ( @xmath0 ) in isolated and interacting disk galaxies with different masses and hubble types by using chemodynamical simulations with @xmath0 formation on dust grains and dust growth and destruction in interstellar medium ( ism ) .
we particularly focus on the dependences of @xmath0 gas mass fractions ( @xmath1 ) , spatial distributions of h i and @xmath0 , and local @xmath0-scaling relations on initial halo masses ( @xmath2 ) , baryonic fractions ( @xmath3 ) , gas mass fractions ( @xmath4 ) , and hubble types .
the principal results are as follows .
the final @xmath1 can be larger in disk galaxies with higher @xmath2 , @xmath3 , and @xmath4 .
some low - mass disk models with @xmath2 smaller than @xmath5 show extremely low @xmath1 and thus no / little star formation , even if initial @xmath4 is quite large ( @xmath6 ) .
big galactic bulges can severely suppress the formation of @xmath0 from h i on dust grains whereas strong stellar bars can not only enhance @xmath1 but also be responsible for the formation of @xmath0-dominated central rings .
the projected radial distributions of @xmath0 are significantly more compact than those of h i and the simulated radial profiles of @xmath0-to - h i - ratios ( @xmath7 ) follow roughly @xmath8 in mw - type disk models .
galaxy interaction can significantly increase @xmath1 and total @xmath0 mass in disk galaxies .
the local surface mass densities of @xmath0 can be correlated with those of dust in a galaxy .
the observed correlation between @xmath7 and gas pressure ( @xmath9 ) can be well reproduced in the simulated disk galaxies .
[ firstpage ] ism : molecules galaxies : ism galaxies : evolution infrared : galaxies stars : formation .
And you have already written the first three sentences of the full article: formation and evolution processes of molecular hydrogen ( @xmath0 ) and interstellar dust in galaxies can be strongly coupled , because the surface of dust grains can be the major formation sites of @xmath0 ( e.g. , gould & salpeter 1963 ; hollenbach & salpeter 1971 ) .
dust has long been considered to play decisive roles in several aspects of star and galaxy formation , such as radiative cooling processes in star - forming clouds ( e.g. , herbst 2001 ) and the formation of metal - poor low - mass stars in the early universe ( e.g. , schneider & omukai 2010 ) .
likewise , @xmath0 is an essential element in giant molecular clouds where star formation is ongoing ( e.g. , blitz et al ..
Please generate the next two sentences of the article | 2007 ; fukui & kawamura 2010 ) and its physical properties ( e.g. , mass densities ) are key parameters for the observed star - formation laws in galaxies ( e.g. , bigiel et al .
2008 ; leroy et al . |
5,363 | Suppose that you have an abstract for a scientific paper: for the lithium dimer we calculate cross sections for absorption of radiation from the vibrational - rotational levels of the ground @xmath0 electronic state to the vibrational levels and continua of the excited @xmath1 and @xmath2 electronic states .
theoretical and experimental data are used to characterize the molecular properties taking advantage of knowledge recently obtained from photoassociation spectroscopy and ultra - cold atom collision studies .
the quantum - mechanical calculations are carried out for temperatures in the range from 1000 to 2000 k and are compared with previous calculations and measurements . .
And you have already written the first three sentences of the full article: the absorption spectra of pure alkali - metal vapors at temperatures of the order 1000 k can be a rich source of information on molecular potentials and properties . achieving a high vapor pressure of lithium in experiments requires higher temperatures than the other alkali - metal atoms , but there are some data from heat pipe ovens @xcite and from a specialized apparatus @xcite .
in addition to the atomic lines the spectra exhibit gross molecular features attributable to transitions between bound levels of the ground electronic state and levels of the excited singlet states and weaker features arising from analogous triplet transitions . theoretically , the envelope of the alkali - metal molecular absorption spectra can be quantitatively reproduced using semi - classical models @xcite and ro - vibrational structure @xcite and continua @xcite can be reproduced from quantum - mechanical models . in this paper
we calculate quantum - mechanically absorption spectra for the @xmath0@xmath1 and @xmath0@xmath2 transitions in @xmath3 ..
Please generate the next two sentences of the article | although both semi - classical @xcite and quantum - mechanical @xcite calculations have been performed and compared @xcite previously for these transitions of @xmath3 , recent improvements in the molecular data prompt the present comprehensive study . from photoassociation spectroscopy and cold collision studies performed in the last few years as well as recent theoretical work
there have been significant critical tests of and improvements to the molecular potentials@xcite , particularly at long - range @xcite , and transition dipole moment data @xcite available for @xmath3 , as well as to the value of the lifetime of the li @xmath4 state @xcite . |
5,364 | Suppose that you have an abstract for a scientific paper: an introductory review on the critical behaviour of some irreversible reaction systems is given .
the study of these systems has attracted great attention during the last decades due to , on the one hand , the rich and complex underlying physics , and on the other hand , their relevance for numerous technological applications in heterogeneous catalysis , corrosion and coating , development of microelectronic devices , etc .. the review is focuses on recent advances in the understanding of irreversible phase transitions ( ipt s ) providing a survey of the theoretical development of the field during the last decade , as well as a detailed discussion of relevant numerical simulations .
the langevin formulation for the treatment of second - order ipt s is discussed .
different monte carlo approaches are also presented in detail and the finite - size scaling analysis of second - order ipt s is described .
special attention is devoted to the description of recent progress in the study of first - order ipt s observed upon catalytic oxidation of carbon monoxide and the reduction of nitrogen monoxide , using lattice gas reaction models .
only brief comments are given on other reactions such as the oxidation of hydrogen , ammonia synthesis , etc .
also , a discussion of relevant experiments is presented and measurement are compared with the numerical results .
furthermore , promising areas for further research and open questions are also addressed .
= 20pt # 1 .
And you have already written the first three sentences of the full article: the study and understanding of heterogeneously catalyzed reactions is a field that contains an enormous wealth of still unclear or even completely unexplained phenomena .
this scenario leads to an exciting and challenging domain for investigation and fundamental research .
furthermore , the occurrence of many complex and fascinating physical and chemical phenomena , such as pattern formation and self - organization @xcite , regular and irregular kinetic oscillations @xcite , propagation and interference of chemical waves and spatio - temporal structures @xcite , the transition into chaotic behaviour @xcite , fluctuation - induced transitions @xcite , irreversible phase transitions ( ipt s ) @xcite , etc , has attracted the attention of many scientists ..
Please generate the next two sentences of the article | in addition to the basic interest , heterogeneous catalysis is a field of central importance for numerous industrial ( e.g. synthesis of ammonia , sulfuric and nitric acids , cracking and reforming processes of hydrocarbons , etc . ) and practical ( e.g. catalytic control of environmental pollution such as the emission of @xmath0 , @xmath1 , @xmath2 , @xmath3 , etc . ) applications .
furthermore , information technology , material science , corrosion , energy conversion , ecology and environmental sciences , etc . |
5,365 | Suppose that you have an abstract for a scientific paper: the measurement of @xmath0 from @xmath1 does not resolve the discrete ambiguities in the angle @xmath2 .
a measurement of @xmath3 is therefore desirable .
this talk is about measuring the ckm angle @xmath4 from various @xmath5 decays to charm final states which also allow us a measurement of @xmath3 . .
And you have already written the first three sentences of the full article: we already have a precise measurement of @xmath0 from @xmath1
. however this measurement does not resolve the 4 fold ambiguity in @xmath2 : @xmath6 we want to measure the angle @xmath2 in many processes to test the sm .
also measurement of both @xmath0 and @xmath3 is clearly desirable to partly resolve the discrete ambiguity in @xmath2 . in this talk.
Please generate the next two sentences of the article | i will review the theory of measuring the ckm angle @xmath4 from various @xmath5 decays to charm final states .
i will concentrate on @xmath7 , @xmath8 . |
5,366 | Suppose that you have an abstract for a scientific paper: inspired by the recent measurement of the b(e2;@xmath0 ) and b(e0;@xmath1 ) values in @xmath2be , we give an interpretation of available spectroscopic data on both @xmath2be and @xmath3be , using a simple model which contains the essential feature of these two nuclei ; the presence of weakly - bound neutron(s ) in deformed potentials .
the agreement of the calculated results with observed data is surprisingly good , including well - known strong e1 transitions in both nuclei . .
And you have already written the first three sentences of the full article: the study of the properties of nuclei far from the line of @xmath4 stability is currently one of the most active and challenging topics in nuclear structure .
exotic ratios of z / n for a given mass number together with the presence of weakly bound nucleons lead to the phenomena which are unexpected from our common sense about stable nuclei ; among others , one finds the change of the shell structure and magic numbers . observed properties of low - lying states in @xmath5be@xmath6 and @xmath7be@xmath8 have contributed to the finding that n=8 is no longer a magic number in such unstable nuclei . though there have been already many elaborate attempts to describe the structure of be isotopes ,
in the present paper we give an interpretation of available spectroscopic data on @xmath2be and @xmath3be keeping a model as simple as possible , while taking duly into account the essential feature of these nuclei ; the presence of weakly - bound neutron(s ) in finite deformed potentials . a simplest version of bohr - mottelson model ( see chaps . 4 and 5 of ref ..
Please generate the next two sentences of the article | @xcite ) is applied to the nuclei @xmath3be and @xmath2be , using weakly - bound one - particle wave - functions estimated properly with deformed woods - saxon potentials instead of harmonic - oscillator potentials .
the present work is prompted by the recent lifetime measurements of the 0@xmath9 state in @xmath2be @xcite . |
5,367 | Suppose that you have an abstract for a scientific paper: we study coherent structures in solar photospheric flows in a plage in the vicinity of the active region ar 10930 using the horizontal velocity data derived from hinode / sot magnetograms .
eulerian and lagrangian coherent structures are detected by computing the q - criterion and the finite - time lyapunov exponents of the velocity field , respectively .
our analysis indicates that , on average , the deformation eulerian coherent structures dominate over the vortical eulerian coherent structures in the plage region .
we demonstrate the correspondence of the network of high magnetic flux concentration to the attracting lagrangian coherent structures ( a - lcs ) in the photospheric velocity based on both observations and numerical simulations .
in addition , the computation of a - lcs provides a measure of the local rate of contraction / expansion of the flow . .
And you have already written the first three sentences of the full article: the spatiotemporal patterns and transport of magnetic field in the photosphere are driven by the turbulent plasma flows in the solar convection zone .
solar magnetic fields are observed in complex and hierarchical structures covering a wide range of scales that emerge and vanish on the time - scales of turbulent convective patterns .
traditionally , they are classified by size and lifetime as patterns of granulation ( 1 mm , 0.2 h ) , mesogranulation ( 5 - 10 mm , 5 h ) and supergranulation ( 15 - 35 mm , 24 h ) ..
Please generate the next two sentences of the article | recently , the idea is emerging that meso and supergranulation are signatures of a collective interaction of granular cells @xcite .
the continuous restructuring of surface magnetic fields by photospheric turbulent flows plays a key role in determining the topology and evolution of chromospheric and coronal magnetic fields , and may influence the triggering of eruptive solar events such as flares , coronal mass ejections or sudden disappearance of filaments @xcite . |
5,368 | Suppose that you have an abstract for a scientific paper: recent work by polyanskiy et al . and chen et al . has excited new interest in using feedback to approach capacity with low latency .
polyanskiy showed that feedback identifying the first symbol at which decoding is successful allows capacity to be approached with surprisingly low latency .
this paper uses chen s rate - compatible sphere - packing ( rcsp ) analysis to study what happens when symbols must be transmitted in packets , as with a traditional hybrid arq system , and limited to relatively few ( six or fewer ) incremental transmissions .
numerical optimizations find the series of progressively growing cumulative block lengths that enable rcsp to approach capacity with the minimum possible latency .
rcsp analysis shows that five incremental transmissions are sufficient to achieve 92% of capacity with an average block length of fewer than 101 symbols on the awgn channel with snr of 2.0 db .
the rcsp analysis provides a decoding error trajectory that specifies the decoding error rate for each cumulative block length . though rcsp is an idealization , an example tail - biting convolutional code matches the rcsp decoding error trajectory and achieves 91% of capacity with an average block length of 102 symbols on the awgn channel with snr of 2.0 db .
we also show how rcsp analysis can be used in cases where packets have deadlines associated with them ( leading to an outage probability ) . .
And you have already written the first three sentences of the full article: though shannon showed in 1956 @xcite that noiseless feedback does not increase the capacity of memoryless channels , feedback s other benefits have made it a staple in modern communication systems .
feedback can simplify the encoding and decoding operations and has been incorporated into incremental redundancy ( ir ) schemes proposed as early as 1974 @xcite .
hagenauer s work on rate - compatible punctured convolutional ( rcpc ) codes allows the same encoder to be used in various channel conditions and uses feedback to determine when to send additional coded bits @xcite ..
Please generate the next two sentences of the article | the combination of ir and hybrid arq ( harq ) continues to receive attention in the literature @xcite and industry standards such as 3gpp .
although it can not increase capacity in point - to - point channels , the information - theoretic benefit of feedback for reducing latency through a significant improvement in the error exponent has been well understood for some time . |
5,369 | Suppose that you have an abstract for a scientific paper: the notion of absorption was developed a few years ago by barto and kozik and immediately found many applications , particularly in topics related to the constraint satisfaction problem .
we investigate the behavior of absorption in semigroups and @xmath0-ary semigroups ( that is , algebras with one @xmath0-ary associative operation ) . in the case of semigroups
, we give a simple necessary and sufficient condition for a semigroup to be absorbed by its subsemigroup .
we then proceed to @xmath0-ary semigroups , where we conjecture an analogue of this necessary and sufficient condition , and prove that the conjectured condition is indeed necessary and sufficient for @xmath1 to absorb @xmath2 ( where @xmath2 is an @xmath0-ary semigroup and @xmath1 is its @xmath0-ary subsemigroup ) in the following three cases : when @xmath2 is commutative , when @xmath3 and when @xmath2 is an idempotent ternary semigroup . .
And you have already written the first three sentences of the full article: let @xmath2 be an algebra and @xmath4 .
we say that @xmath1 _ absorbs _ @xmath2 , denoted by @xmath5 , iff there exists an idempotent term @xmath6 in @xmath2 ( that is , @xmath7 for each @xmath8 ) such that for each @xmath8 and @xmath9 we have @xmath10 the notion of absorption was developed a few years ago by barto and kozik , and immediately found many applications @xcite .
we would particularly like to mention that bulatov s dichotomy theorem for conservative csps @xcite , with a deep and complicated proof ( nearly 70 pages long ) , was reproved using these techniques on merely 10 pages @xcite ..
Please generate the next two sentences of the article | loosely speaking , the main idea of absorption is that , when @xmath5 where @xmath1 is a proper subalgebra of @xmath2 , then some induction - like step can often be applied .
this naturally leads to the following question : given a finite algebra @xmath2 and its subalgebra @xmath1 , is it decidable whether @xmath5 ? |
5,370 | Suppose that you have an abstract for a scientific paper: inspired by the fact that people have diverse propensities to punish wrongdoers , we study a spatial public goods game with defectors and different types of punishing cooperators . during the game , cooperators punish defectors with class - specific probabilities and subsequently share the associated costs of sanctioning .
we show that in the presence of different punishing cooperators the highest level of public cooperation is always attainable through a selection mechanism .
interestingly , the selection not necessarily favors the evolution of punishers who would be able to prevail on their own against the defectors , nor does it always hinder the evolution of punishers who would be unable to prevail on their own .
instead , the evolutionary success of punishing strategies depends sensitively on their invasion velocities , which in turn reveals fascinating examples of both competition and cooperation among them .
furthermore , we show that under favorable conditions , when punishment is not strictly necessary for the maintenance of public cooperation , the less aggressive , mild form of sanctioning is the sole victor of selection process .
our work reveals that natural strategy selection can not only promote , but sometimes also hinder competition among prosocial strategies . .
And you have already written the first three sentences of the full article: cooperation is vital for the maintenance of public goods in human societies @xcite . but according to darwin s theory of evolution , competition rather than cooperation ought to drive our actions .
the reconciliation of this theory with the fact that cooperation is widespread in human societies , as well as with the fact that it is much more common in nature as one might expect , is one of the most persistent challenges in evolutionary biology and social sciences @xcite .
past decades have seen the paradigm of punishment rise as one of the more successful strategies by means of which cooperation might be promoted @xcite ..
Please generate the next two sentences of the article | indeed , punishment is also the principle tool of institutions in human societies for maintaining cooperation and otherwise orderly behavior @xcite .
however , punishment is costly , and as such it reduces the payoffs of both the defectors as well as of those that exercise the punishment , hence yielding an overall lower income and acting as a drain on social welfare . |
5,371 | Suppose that you have an abstract for a scientific paper: we established a sample of millimeter - wave and @xmath0-ray bright active galactic nuclei matching the _ wmap _ catalog with the egret catalog , highest energy photons and the _ fermi _ bright source list .
we have monitored over 80 of these objects in the near infrared , obtaining over 2000 jhks data points directly comparable with _ fermi _ data .
we present examples of correlated near infrared and @xmath0-ray activity of known blazars and recently identified sources . .
And you have already written the first three sentences of the full article: _ cgro_-egret established the predominance of flat spectrum radio quasars ( fsrq ) as extragalactic sources of high - energy @xmath0-rays @xcite .
these are believed to be powered by supermassive black holes ejecting large amounts of material along relativistic jets perpendicular to accretion disks and producing high energy particles in these jets .
observations at the highest photon energies shown a predominance of bl lac objects over fsrq at @xmath1 ..
Please generate the next two sentences of the article | although these observations may be biased by the horizon limitation due to pair absorption with extragalactic background light ( ebl ) , the _ fermi _
@xmath0-ray space telescope , more sensitive and more responsive to gev photons than egret , reported a larger fraction of bl lac objects among blazars in its bright source list release ( 0fgl ) @xcite . |
5,372 | Suppose that you have an abstract for a scientific paper: irreversible adsorption of spheres on flat collectors having dimension @xmath0 is studied .
molecules are adsorbed on sierpinski s triangle and carpet like fractals ( @xmath1 ) , and on general cantor set ( @xmath2 ) .
adsorption process is modeled numerically using random sequential adsorption ( rsa ) algorithm .
the paper concentrates on measurement of fundamental properties of coverages , i.e. maximal random coverage ratio and density autocorrelation function , as well as rsa kinetics .
obtained results allow to improve phenomenological relation between maximal random coverage ratio and collector dimension .
moreover , simulations show that , in general , most of known dimensional properties of adsorbed monolayers are valid for non - integer dimensions . .
And you have already written the first three sentences of the full article: most of the effort in the research on irreversible adsorption is focused on flat homogeneous surfaces as it can be further directly exploited in material sciences .
however , experiments using fractal - like collectors were also made @xcite , though preparation of such surfaces is complicated . on the other hand , there are many porous media in nature and adsorption may play an important role there @xcite .
for example , coral fractal - like structure helps them to catch plankton effectively @xcite ..
Please generate the next two sentences of the article | adsorption on fractal collectors might also be applied in environmental protection in designing effective water or air filters @xcite .
hard spheres packing has a rich research history , both in physics and maths . |
5,373 | Suppose that you have an abstract for a scientific paper: the spontaneous generation of the chromomagnetic field at high temperature is investigated in a lattice formulation of the @xmath0-gluodynamics .
the procedure of studying this phenomenon is developed .
the monte carlo simulations of the free energy on the lattices @xmath1 , @xmath2 and @xmath3 at various temperatures are carried out .
the creation of the field is indicated by means of the @xmath4-analysis of the data set accumulating 5 - 10 millions mc configurations .
a comparison with the results of other approaches is done . .
And you have already written the first three sentences of the full article: among interesting problems of modern cosmology the origin of large - scale magnetic fields is intensively attacked nowadays .
various mechanisms of the field generation at different stages of the universe evolution were proposed @xcite .
basically they are grounded on the idea of fermi , chandrasekhar and zeldovich that to have the present day galaxy magnetic fields of order @xmath5 correlated on a scale @xmath6mpc seed magnetic fields must be present in the early universe ..
Please generate the next two sentences of the article | these fields had been frozen in a cosmic plasma and then amplified by some of the mechanisms of the field amplification .
one of the ways to produce seed fields is a spontaneous vacuum magnetization at high temperature @xmath7 @xcite . |
5,374 | Suppose that you have an abstract for a scientific paper: we study the infinite @xmath0 hubbard model with one hole doped away half - filling , in triangular and square lattices with frustrated hoppings that invalidate nagaoka s theorem , by means of the density matrix renormalization group .
we find that these kinetically frustrated models have antiferromagnetic ground states with classical local magnetization in the thermodynamic limit .
we identify the mechanism of this kinetic antiferromagnetism with the release of the kinetic energy frustration as the hole moves in the established antiferromagnetic background .
this release can occurs in two different ways : by a non - trivial spin - berry phase acquired by the hole or by the effective vanishing of the hopping amplitude along the frustrating loops .
itinerant magnetism has proved to be an elusive subject in condensed matter physics , since itinerant and localized aspects of electrons need to be taken into account on equal footing .
the single - band hubbard model , originally proposed to describe metallic ferromagnetism @xcite , has also been associated with antiferromagnetism of kinetic exchange origin close to half - filling . while _ virtual _ kinetic processes favor antiferromagnetism , it is a rule of thumb to link _ real _ kinetic processes with ferromagnetism @xcite .
however , there exist only few exact results ensuring the existence of itinerant ferromagnetism @xcite . among them ,
the most renowned is nagaoka s theorem @xcite , which assert that the saturated ferromagnetic state is the unique ground state when one hole is doped on the half - filled hubbard model with infinite @xmath0 coulomb repulsion .
furthermore , a connectivity condition must be fulfilled for the validity of nagaoka s theorem : the sign of the hopping amplitudes around the smallest closed loop of the lattice must be positive , otherwise the hole kinetic energy will be frustrated and the saturated ferromagnetic state will no longer be the ground state . kinetic energy frustration is a quantum mechanical....
And you have already written the first three sentences of the full article: here we present the slave - fermion mean - field results for the @xmath59 model with @xmath33 , that allow us to interpret the physical origin of the kinetic antiferromagnetism found numerically with the dmrg method .
first , we briefly introduce the slave - fermion mean - field treatment @xcite of the @xmath59 model , @xmath104 where the sum @xmath105 is over all the @xmath65 sites of the cluster and all the @xmath80 neighbors connected with @xmath65 by the exchange interaction @xmath106 and hopping term @xmath107 the @xmath59 model is the strong coupling @xmath108 limit of the hubbard model , with @xmath109 , and it is written in terms of the projected electronic operators , @xmath110 with @xmath111 forbidding the electronic double occupancy at each site . for @xmath3 , @xmath112 , and both models are identical .
the projected electronic operators can be represented in term of schwinger bosons @xmath113 and spinless fermions @xmath114 @xmath115 this replacement , together with the constraint @xmath116 at each site @xmath65 , is a faithful representation of the original fermi algebra ..
Please generate the next two sentences of the article | the spin can be written in terms of the schwinger bosons as @xmath117 , where @xmath118 is the vector of pauli matrices , while the slave fermion @xmath119 corresponds to the charge ( hole ) degree of freedom .
we replace ( [ cproj ] ) in the @xmath59 hamiltonian ( [ tj ] ) and we obtain @xmath120 , \label{tjslave}\ ] ] where we have defined the singlet @xmath6 operators @xmath121 and @xmath122 @xcite , while @xmath123 . |
5,375 | Suppose that you have an abstract for a scientific paper: the relative error of cloning of quantum states with arbitrary prior probabilities is considered .
it is assumed that the ancilla may contain some _ a priori _ information about the input state to be cloned .
the lower bound on the relative error for general cloning scenario is derived .
both the case of two - state set and case of multi - state set are analyzed in details .
the treated figure of merit is compared with other optimality criteria .
the quantum circuit for optimal cloning of a pair of pure states is constructed . .
And you have already written the first three sentences of the full article: the quantum information topics are the subject of active research @xcite .
the impressive progress have been reached in the quantum cryptography @xcite and study of quantum algorithms @xcite . due to an impact on security in quantum cryptography ,
the quantum cloning is still a significant topic . at the same time.
Please generate the next two sentences of the article | , a cloning itself is hardly sufficient for an eavesdropping @xcite .
no - copying results have been established for pure states @xcite as well as for mixed states @xcite . in view of such evidences , |
5,376 | Suppose that you have an abstract for a scientific paper: ideal hydrodynamic models of the intracluster medium ( icm ) in the core regions of galaxy clusters fail to explain both the observed temperature structure of this gas , and the observed morphology of radio - galaxy / icm interactions .
it has recently been suggested that , even in the presence of reasonable magnetic fields , thermal conduction in the icm may be crucial for reproducing the temperature floor seen in many systems .
if this is indeed correct , it raises the possibility that other transport processes may be important . with this motivation
, we present a numerical investigation of the buoyant evolution of agn - blown cavities in icm that has a non - negligible shear viscosity .
we use the zeus - mp code to follow the 3-dimensional evolution of an initially static , hot bubble in a @xmath0-model icm atmosphere with varying degrees of shear viscosity . with no explicit viscosity
, it is found that the combined action of rayleigh - taylor and kelvin - helmholtz instabilities rapidly shred the icm cavity and one does not reproduce the intact and detached `` ghost cavities '' observed in systems such as perseus - a . on the other hand , even a modest level of shear viscosity ( corresponding to approximately 25% of the spitzer value ) can be important in quenching the fluid instabilities and maintaining the integrity of the bubble .
in particular , we show that the morphology of the nw ghost cavity found in perseus - a can be reproduced , as can the flow pattern inferred from the morphology of h@xmath1 filaments .
finally , we discuss the possible relevance of icm viscosity to the fact that many of the active icm cavities ( i.e. , those currently associated with active radio - lobes ) are not bounded by strong shocks , the so - called `` shock problem '' .
= -1 cm [ firstpage ] cooling flows galaxies : jets hydrodynamics radio galaxies x - rays : galaxies : clusters .
And you have already written the first three sentences of the full article: recent years have seen a growing realization that the cores of rich galaxy clusters are complex and dynamic environments . in particular , it is becoming clear that the radio - loud active galactic nuclei ( agn ) often hosted by the cd galaxies in rich clusters can have a major influence on the hydrodynamics and thermodynamics of the core regions of the intracluster medium ( icm ) . as we discuss below , the rich datasets coming from the _ chandra x - ray observatory _ and _ xmm - newton _ now demand theoretical models that go beyond the simple picture of jet - blown `` bubbles '' rising in a static icm described by ideal hydrodynamics .
bulk icm motions ( including turbulence ) , magnetohydrodynamics ( mhd ) , thermal conductivity , and viscosity may all be relevant to data that are currently being taken . even before the launches of _ chandra _ and _ xmm - newton _ , _ einstein _ and _ rosat _ studies revealed prominent radio - galaxy / cluster interactions in three clusters ; perseus - a ( bhringer et al .
1993 ; heinz , reynolds & begelman 1998 ) , virgo - a ( feigelson et al ..
Please generate the next two sentences of the article | 1987 ; bringer et al . 1995 ) and cygnus - a ( carilli , perley & harris 1994 ; harris , carilli & perley 1994 ) .
_ rosat _ showed perseus - a and cygnus - a to possess intracluster medium ( icm ) cavities coincident with the prominent radio - lobes in these two sources , suggesting supersonic inflation of a bubble in the icm by the jetted agn ( clarke , harris & carilli 1997 ) . |
5,377 | Suppose that you have an abstract for a scientific paper: we present an extensive synthetic observational analysis of numerically - simulated radio galaxies designed to explore the effectiveness of conventional observational analyses at recovering physical source properties .
these are the first numerical simulations with sufficient physical detail to allow such a study .
the present paper focuses on extraction of magnetic field properties from nonthermal intensity information .
synchrotron and inverse - compton intensities were effective in providing meaningful information about distributions and strengths of magnetic fields , although considerable care was called for in quantitative usage of the information .
correlations between radio and x - ray surface brightness correctly revealed useful dynamical relationships between particles and fields , for example .
magnetic field strength estimates derived from the ratio of x - ray to radio intensity were mostly within about a factor of two of the rms field strength along a given line of sight .
when emissions along a given line of sight were dominated by regions close to the minimum energy / equipartition condition , the field strengths derived from the standard power - law - spectrum minimum energy calculation were also reasonably close to actual field strengths , except when spectral aging was evident .
otherwise , biases in the minimum - energy magnetic field estimation mirrored actual differences from equipartition .
the ratio of the inverse - compton - estimated magnetic field to the minimum - energy magnetic field provided a rough measure of the actual total energy in particles and fields in most instances , although this measure was accurate within only about an order of magnitude .
this may provide a practical limit to the accuracy with which one may be able to establish the internal energy density or pressure of optically thin synchrotron sources . .
And you have already written the first three sentences of the full article: the synchrotron emission from extragalactic radio sources is a function of both the local magnetic fields and the relativistic particle populations residing within .
these two components are important to the energy budget of such objects .
so , pinning down their relative contributions is crucial to understanding their overall behavior ..
Please generate the next two sentences of the article | unfortunately , the optically - thin synchrotron emission alone can not be used to extract the individual particle and field components .
however , it has long been known that in principle radio synchrotron observations can be combined with x - ray observations of inverse - compton scattered cosmic microwave background photons ( hereafter ic/3k ) to extract information about particles and fields in emission regions ( e.g. , * ? ? ? |
5,378 | Suppose that you have an abstract for a scientific paper: in this article we consider commuting graphs of involution conjugacy classes in the affine weyl group of type @xmath0 .
we show that where the graph is connected the diameter is at most @xmath1 .
+ msc(2000 ) : 20f55 , 05c25 , 20d60 . .
And you have already written the first three sentences of the full article: consider @xmath2 a subset of a group @xmath3 .
the elements of @xmath2 constitute the vertices of the commuting graph @xmath4 , in which @xmath5 are joined by an edge whenever @xmath6 .
if @xmath2 is a set of involutions then we call @xmath4 a commuting involution graph ..
Please generate the next two sentences of the article | commuting graphs have been studied by many authors in various contexts .
for example fischer @xcite studied commuting involution graphs for the case when @xmath2 is a conjugacy class of involutions , in his work on 3-transposition groups . |
5,379 | Suppose that you have an abstract for a scientific paper: we investigate the exchange bias and training effects in the fm / af heterostructures using a unified monte carlo dynamical approach .
this real dynamical method has been proved reliable and effective in simulating dynamical magnetization of nanoscale magnetic systems .
the magnetization of the uncompensated af layer is still open after the first field cycling is finished .
our simulated results show obvious shift of hysteresis loops ( exchange bias ) and cycling dependence of exchange bias ( training effect ) when the temperature is below 45 k. the exchange bias fields decrease with decreasing the cooling rate or increasing the temperature and the number of the field cycling . with the simulations
, we show the exchange bias can be manipulated by controlling the cooling rate , the distributive width of the anisotropy energy , or the magnetic coupling constants .
essentially , these two effects can be explained on the basis of the microscopical coexistence of both reversible and irreversible moment reversals of the af domains .
our simulated results are useful to really understand the magnetization dynamics of such magnetic heterostructures .
this unified nonequilibrium dynamical method should be applicable to other exchange bias systems . .
And you have already written the first three sentences of the full article: usually , when the heterostructure consisting of coupled ferromagnetic ( fm ) and antiferromagnetic ( af ) layers is cooled in field below the neel temperature of its af component , it shows the asymmetric magnetization @xcite , which is referred to as the exchange bias effect .
furthermore , the exchange bias field , defined as the average of the two coercive fields , is observed to decrease with increasing the number of the consecutive field cycling , which is referred to as the training effect@xcite .
the exchange bias and training effects are very interesting and could be used in future spintronics@xcite and data storage ..
Please generate the next two sentences of the article | usually , the fm layer is taken as a whole and the af layer consists of many grains .
the af grain is small enough to consists of a single domain , and some uncompensated domains ( or grains ) may be formed by defects or impurities@xcite and couple with each other and with the fm domains . as the heterostructure is cooled to a low temperature , |
5,380 | Suppose that you have an abstract for a scientific paper: it is well known that boundary conditions on quantum fields produce divergences in the renormalized energy - momentum tensor near the boundaries .
although irrelevant for the computation of casimir forces between different bodies , the self - energy couples to gravity , and the divergences may , in principle , generate large gravitational effects .
we present an analysis of the problem in the context of quantum field theory in curved spaces .
our model consists of a quantum scalar field coupled to a classical field that , in a certain limit , imposes dirichlet boundary conditions on the quantum field .
we show that the model is renormalizable and that the divergences in the renormalized energy - momentum tensor disappear for sufficiently smooth interfaces . .
And you have already written the first three sentences of the full article: the vacuum energy produces measurable forces between neutral bodies @xcite . but even in the presence of a single body , the modes of the electromagnetic field are disturbed and produce a self - energy .
although irrelevant for the calculation of forces between different objects , this self - energy is in principle observable through its coupling to gravity . in the case of perfect conductors , the vacuum energy density , or more generally the energy - momentum tensor ,
diverges near the boundaries , as noted for the first time by deutsch and candelas a long time ago @xcite ..
Please generate the next two sentences of the article | these divergences are not the usual ones in quantum field theory , because they are present in the _ already renormalized _ energy - momentum tensor .
the origin of the divergences is the unphysical assumption of perfect conductivity for all modes of the electromagnetic field since , on physical grounds , one expects any material to become transparent at high energies . |
5,381 | Suppose that you have an abstract for a scientific paper: correlation functions of discrete primary fields in the @xmath0 boundary conformal field theory of a scalar field in a critical periodic boundary potential are computed using the underlying @xmath1 symmetry of the model .
bulk amplitudes are unambigously determined and we give a prescription for amplitudes involving discrete boundary fields . .
And you have already written the first three sentences of the full article: we consider a two - dimensional scalar field @xmath2 defined on the upper - half - plane , @xmath3 , which is free in the two - dimensional bulk but subject to a periodic boundary potential .
the action is @xmath4 where @xmath5 is a complex parameter which dials the strength and the phase of the periodic boundary interaction .
the period of the potential is chosen such that the interaction has dimension one under boundary scaling ..
Please generate the next two sentences of the article | this ensures that the boundary theory preserves half of the conformal symmetry of the bulk system .
this model arises in various contexts , for example , in connection with critical behavior in dissipative quantum mechanics @xcite , quantum hall edge states @xcite , and open string theory in an on - shell tachyon background @xcite . |
5,382 | Suppose that you have an abstract for a scientific paper: the distribution of votes of one of the corporate parties in mexico during elections of 2000 , 2003 and 2006 is analyzed .
after proper normalization and unfolding , the agreement of the votes distributions with those of daisy models of several ranks is good .
these models are generated by retaining each @xmath0 level in a sequence which follows a poisson distribution .
beyond the fact that rank @xmath1 daisy model resembles the distribution of the quasi - optimal distances for the traveling salesman problem , no clear explanation exists for this behavior , but the agreement is not fortuitous and the possibility of a universal phenomena for corporate vote is discussed . .
And you have already written the first three sentences of the full article: several recent efforts have been done in order to understand the subyacent dynamics in electoral systems and opinion formation @xcite , from the contrarian effect@xcite to the , so called , small world behavior@xcite . in the brazilian elections , for instance , power law was found for the proportional vote@xcite .
however , to establish a proper description of an electoral process is a hard issue since many factors and interactions appear and several aspects of them must be studied
. statistical characterization of actual processes is an important issue as well , mainly with the increasing possibility of obtaining the vote data . in the present work.
Please generate the next two sentences of the article | we incorporate the analysis on the corporate vote with a study on the statistical properties of the federal mexican elections of 2000(e-2000 ) , 2003(e-2003 ) , and 2006(e-2006 ) . since their distributions are smooth , the existence of an analytical distribution that describes them and a model which explains them , are very tempting issues .
we were successful in the first topic but the answers to the second remain open . |
5,383 | Suppose that you have an abstract for a scientific paper: the high - energy gamma - ray emission discovered using the h.e.s.s .
telescopes from the binary system psr b1259 @xmath063 , is modelled using an extension of the approach that successfully predicted it .
we find that the simultaneous integral and h.e.s.s .
data permit both a model with dominant radiative losses , high pulsar wind lorentz factor and modest efficiency as well as one with dominant adiabatic losses , a slower wind and higher efficiency .
additional , simultaneous , x - ray and tev data sets are needed to lift this degeneracy . .
And you have already written the first three sentences of the full article: the radio pulsar psr b1259 @xmath063 is in a highly elliptical orbit about the luminous be star ss2883 .
pulsar winds are expected to accelerate electrons to lorentz factors of up to @xmath1 , leading to up - scattering of the ultra - violet photons from the be star into the tev range @xcite .
this can happen before or after the wind passes through its termination shock @xcite ..
Please generate the next two sentences of the article | however , in the case of psr b1259 @xmath063 , the time spent by an individual electron in the unshocked wind is short compared to the time spent in the vicinity of the be star after passing the shock .
thus , even if the shock simply isotropises the electrons without energising them , the post - shock emission should dominate over the pre - shock emission . |
5,384 | Suppose that you have an abstract for a scientific paper: we demonstrate superadditivity in the communication capacity of a binary alphabet consisting of two nonorthogonal quantum states . for this scheme ,
collective decoding is performed two transmissions at a time .
this improves upon the previous schemes of sasaki _
et al_. [ phys .
rev .
a * 58 * , 146 ( 1998 ) ] where superadditivity was not achieved until a decoding of three or more transmissions at a time .
this places superadditivity within the regime of a near - term laboratory demonstration .
we propose an experimental test based upon an alphabet of low photon - number coherent states where the signal decoding is done with atomic state measurements on a single atom in a high - finesse optical cavity .
pacs number(s ) : 03.67.-a , 03.67.dd , 03.67.lx , 03.67.hk , 03.65.bz , 32.80.-t , 33.55.ad , 42.65.pc .
And you have already written the first three sentences of the full article: this paper is about achieving the maximal information transfer rate possible when information is encoded into quantum systems via the preparation of one or another of two nonorthogonal states .
this might at first seem like a questionable thing to consider : for transmissions through a noiseless medium , the maximal transfer rate ( or capacity ) of 1 bit / transmission is clearly achieved _ only _ with orthogonal alphabets .
this is because nonorthogonal preparations can not be identified with complete reliability ..
Please generate the next two sentences of the article | however , there are instances in which it is neither practical nor desirable to use such an alphabet .
the most obvious example is when a simple laser transmitter is located a great distance from the receiver . |
5,385 | Suppose that you have an abstract for a scientific paper: motion of vortices in two - dimensional superfluids in the classical limit is studied by solving the gross - pitaevskii equation numerically on a uniform lattice .
we find that , in the presence of a superflow directed along one of the main lattice periods , vortices move with the superflow on fine lattices but perpendicular to it on coarse ones .
we interpret this result as a transition from the full magnus force in the galilean - invariant limit to vanishing effective magnus force in a discrete system , in agreement with the existing experiments on vortex motion in josephson junction arrays . .
And you have already written the first three sentences of the full article: there is a long - standing interest in how the magnus force , acting on vortices in superfluids and superconductors , changes as the system moves away from the galilean - invariant ( gi ) limit .
indeed , experiments indicate that the effective magnus force is very small both in conventional bulk superconductors except for very clean ones and in `` discrete '' superconductors , formed by josephson - junction arrays ( jja).@xcite in the first instance , there is a convincing explanation for this smallness , based on the spectral flow of fermions at the vortex core.@xcite the spectral flow creates an additional force on the vortex that reduces the total , effective magnus force nearly to zero .
however , the second case has remained something of a mystery ..
Please generate the next two sentences of the article | various explanations of the smallness of the magnus force in jja have been reviewed in ref . .
one proposal is that in this case the magnus force is proportional not to the total density of electrons , but only to the `` offset charges '' , given by the deviation of the system from electrical neutrality.@xcite another proposal is that the effective magnus force vanishes exactly as a consequence of the particle - hole symmetry.@xcite however , volovik @xcite has argued that the particle - hole symmetry in these systems is not exact , and as a result the effective magnus force is nonzero , although small . |
5,386 | Suppose that you have an abstract for a scientific paper: using time- and angle - resolved photoemission spectroscopy with selective near- and mid - infrared photon excitations , we investigate the femtosecond dynamics of the charge density wave ( cdw ) phase in 1_t_-tise@xmath0 , as well as the dynamics of cdw fluctuations at 240 k. in the cdw phase , we observe the coherent oscillation of the cdw amplitude mode . at 240 k
, we single out an ultrafast component in the recovery of the cdw correlations , which we explain as the manifestation of electron - hole correlations .
our momentum - resolved study of femtosecond electron dynamics supports a mechanism for the cdw phase resulting from the cooperation between the interband coulomb interaction , the mechanism of excitonic insulator phase formation , and electron - phonon coupling . .
And you have already written the first three sentences of the full article: materials which exhibit a metal - insulator transition concomitant with a structural phase transition naturally raise questions about the driving mechanism of the phase transition , i.e. if it is possible to single out what is the role played by the electronic or lattice degrees of freedom and how they affect the electronic structure of such materials . in this context
, studies of the non - equilibrium dynamics have opened a new dimension in the investigation of correlated materials in recent years .
time- and angle - resolved photoemission spectroscopy ( trarpes ) has proved to be a major technique , giving access to the momentum - resolved electronic band structure of solids out of equilibrium @xcite . in the case of charge density wave ( cdw ) materials.
Please generate the next two sentences of the article | , the most direct approach follows the photoinduced changes of the cdw spectral features , namely the closing of the cdw gap or the disappearance of the cdw backfolded bands directly in the time - domain .
many studies have focussed on the first hundred femtoseconds following the photoexcitation , in order to figure out whether these changes occur faster or not than the lattice motion related to the structural distortion , the timing of which is given by the period of the relevant phonon mode . |
5,387 | Suppose that you have an abstract for a scientific paper: a formalism is developed which allows to determine the locations of all local symmetry axes of three - dimensional particles with overall icosahedral symmetry .
it relies on the fact that the root system of the non - crystallographic coxeter group @xmath0 encodes the locations of the planes of reflection that generate the discrete rotational symmetries of the particles . via an appropriate extension of the root system , new planes of reflection
are introduced which determine local axes of rotational symmetry .
an easy - to - implement formalism is derived that allows to compute the surface structure of any three - dimensional icosahedral particle with local symmetries .
it can be used also for particles with overall octahedral and tetrahedral symmetry in conjunction with the root systems of the corresponding reflection groups .
applications to viruses are discussed explicitly .
it is shown that the concept of quasi - equivalence in caspar - klug theory corresponds to the special case of local six - fold symmetry axes contained in the theory developed here , and the corresponding geometries can hence be obtained with this formalism based on the root system of @xmath0 . moreover , as a by - product , the theory answers the long - standing open question why only certain types of capsomeres , i.e. clusters of protein subunits , are observed in the surface structures of viruses .
since the types of the capsomeres are determined by the orders of the local symmetry axes on which they are located , the possible types of capsomeres are restricted by the spectrum of local symmetry axes allowed by the theory .
based on this we determine the spectrum of all capsomere types that may occur in viral capsids and give explicit examples for the lower - order cases .
+ + + .
And you have already written the first three sentences of the full article: icosahedrally symmetric particles with local symmetries play a crucial role in virology , because viruses encapsulate their genome in protein containers , called viral capsids , that are organised in protein clusters centred on the symmetry axes of the capsids .
these axes of symmetry may be global , i.e. corresponding to rotations that leave the whole structure invariant and are described by the overall group structure , or local , in which case only the local environments around the symmetry axes .
an example of a local symmetry is the discrete rotation about the centre of the capsomere , that leaves only the capsomere itself , but not the whole capsid , invariant ..
Please generate the next two sentences of the article | the classification of all possible local symmetries of icosahedral surface structures hence determines the spectrum of possible viral capsids with icosahedral symmetry .
viruses with icosahedrally symmetric capsids occur predominantly in nature @xcite . by making use of symmetry |
5,388 | Suppose that you have an abstract for a scientific paper: an appearance of a direct current perpendicularly to a constant component of an electric field in material with rashba hamiltonian under the influence of an elliptically polarized wave is investigated in one - subband approximation . on its physical nature
this effect is close to a circular photogalvanic effect ( cpge ) on intraband transitions .
the effect is studied on the base of two approaches : investigations of boltzmann kinetic equation in a constant collision frequency approximation and semiclassical monte carlo simulations , which immediately takes into account microscopic processes of charge carriers scattering on optical and acoustical phonons .
monte carlo modelling allows us to determine a mean relaxation time and its dependencies on electric field strengths and on the energy of optical phonons . on the base of these estimations a possibility of using a constant relaxation time approximation
is justified .
it is confirmed that the main contribution to the effects of transverse rectification is made by inelastic scattering of electrons on optical phonons .
a comparison of results of monte carlo simulations and calculations on the base of a constant collision frequency approximation is presented .
example.eps !
ps - adobe-3.0 epsf-3.0 gsave newpath 20 20 moveto 20 220 lineto 220 220 lineto 220 20 lineto closepath 2 setlinewidth gsave .4 setgray fill grestore stroke grestore .
And you have already written the first three sentences of the full article: a progress in telecommunications , using of new methods in data transfer , creation of medical equipment are in need of the development of microelectronic devices for generation , commutation and detection of different kinds of signals .
the most actual problem is an engineering of equipments working in terahertz and far infrared range of electromagnetic waves ( see , for example , @xcite ) .
one way to determine the characteristics of high frequency electromagnetic waves ( amplitude , frequency , phase ) is a study of the direct current response which can occur under certain conditions in solid - state structures with non - linear properties ( for example , ) . among the similar phenomena.
Please generate the next two sentences of the article | it should be noted a circular photogalvanic effect ( cpge ) ( see reviews @xcite ) , which was investigated in surface layers of bulk materials @xcite , in thin films @xcite , quantum wells @xcite , in graphene @xcite . without going into details , this effect is consisted in the appearance of a direct current under the influence of elliptically polarized electromagnetic wave with oblique incidence to the surface of the sample .
the current flows perpendicularly to the projection of wave vector on the plane of the sample . by the magnitude of direct current |
5,389 | Suppose that you have an abstract for a scientific paper: cobalt clusters covered with benzene in the form of rice - ball structures have recently been synthesized using laser ablation . here , we investigate the types of magnetic order such clusters have , and whether they retain any magnetic order at all .
we use different density functional theory ( dft ) methods to study the experimentally relevant three cobalt atoms surrounded by benzene rings .
we found that the benzene rings induce a ground state with non - collinear magnetization , with the magnetic moments localized on the cobalt centers and lying on the plane formed by the three cobalt atoms .
this is surprising because nanostructures and small clusters based on pure cobalt typically have a predominantly ferromagnetic order , and additional organic ligands such as benzene tend to remove the magnetization .
we analyse the magnetism of such a cluster using an anisotropic heisenberg model where the involved parameters are obtained by a comparison with the dft results .
moreover , we propose electron paramagnetic resonance as an experimental tool to study the anisotropic response . .
And you have already written the first three sentences of the full article: in recent years , a great deal of attention has been devoted to magnetic organometallic compounds due to their prospective use as nanoscale magnetic devices . for example , single - molecule magnets ( smms)@xcite are currently considered as potential building blocks for spintronics,@xcite molecular electronics,@xcite and quantum computing.@xcite magnetic organometallic molecules can be formed by bringing together small clusters of transition metal atoms and benzene molecules , such as in the case of cobaltocene and ferrocene .
magnetic molecular clusters have been synthesized recently by molecular beams.@xcite their magnetic moments have been measured using stern - gerlach molecular - beam deflections showing that part of the original magnetization may survive when the number of transition metal centers and ligands are comparable .
@xcite contrary to the smms , where the transition metal centers are surrounded by organic compounds and thus , protecting their magnetic moment,@xcite the transition metal atoms in such organometallic clusters are in close proximity , leading to strong exchange interactions ..
Please generate the next two sentences of the article | although these organometallic clusters made up of transition metal clusters and benzene rings share same magnetic properties with smms , their magnetism is much less studied .
bz@xmath0 cluster deposited on a substrate . |
5,390 | Suppose that you have an abstract for a scientific paper: a variety of magnetohydrodynamic mechanisms that may play a role in magnetic , chemically peculiar ( mcp ) stars is reviewed . these involve dynamo mechanisms in laminar flows as well as turbulent environments , and magnetic instabilities of poloidal and toroidal fields as well as combinations of the two .
while the proto - stellar phase makes the survival of primordial fields difficult , the variety of magnetic field configurations on mcp stars may be an indication for that they are instability remnants , but there is no process which is clearly superior in explaining the strong fields . .
And you have already written the first three sentences of the full article: a considerable fraction of chemically peculiar a and b stars ( cp stars ) show strong surface magnetic fields of about 500 g up to over 10 kg .
the evolution of these fields from star formation to their current presence is unknown .
this paper compiles a number of physical processes which may or may not play a role in the whole scenario of cp star magnetism ..
Please generate the next two sentences of the article | the fraction of main - sequence stars with radiative envelopes which show magnetic fields was found to increase from f stars to late b stars ( wolff 1968 ) .
the result was recently confirmed by power et al . |
5,391 | Suppose that you have an abstract for a scientific paper: we report the amplitude scaling behavior of frenkel exciton chains with nearest - neighbor correlated off - diagonal random interactions .
the band center spectrum and its localization properties are investigated through the integrated density of states and the inverse localization length .
the correlated random interactions are produced through a binary sequence similar to the interactions in spin glass chains .
we produced sets of data with different interaction strength and `` wrong '' sign concentrations that collapsed after scaling to the predictions of a theory developed earlier for dirac fermions with random - varying mass .
we found good agreement as the energy approaches the band center for a wide range of concentrations .
we have also established the concentration dependence of the lowest order expansion coefficient of the scaling amplitudes for the correlated case .
the correlation causes unusual behavior of the spectra , i.e. , deviations from the dyson - type singularity .
+ exciton , one dimension , correlated off - diagonal disorder , amplitude scaling 78.20.bh , 78.40.pg,*78.67.@xmath0n * .
And you have already written the first three sentences of the full article: low - dimensional disordered excitonic systems have generated renewed interest recently .
for example , the possibility of using optically active polymers in various photonic applications such as flat panel displays and light emitting diodes has led to increased interest in their electronic and optical properties @xcite .
we study here numerically the dynamics of frenkel excitons near the band center in a system with nearest - neighbor off - diagonal random interactions ..
Please generate the next two sentences of the article | this study is , we believe , the first to treat correlated disorder in the off - diagonal dipolar interactions in an exciton system which focuses on the behavior near band center @xmath1 .
however , an analysis of a similar problem in the correlated electronic system has appeared @xcite but the authors considered correlations those were different from ours , and the interactions were not of the dipolar type @xcite . |
5,392 | Suppose that you have an abstract for a scientific paper: we examine whether the cosmic ray positron excess observed by pamela can be explained by neutralino annihilation in the next - to - minimal supersymmetric standard model ( nmssm ) .
the main dark matter annihilation products are the lightest @xmath0-even scalar @xmath1 plus the lightest @xmath0-odd scalar @xmath2 , with the @xmath2 decaying into two muons .
the energetic positrons needed to explain pamela are thus obtained in the nmssm simply from kinematics .
the required large annihilation cross section is obtained from an @xmath3-channel resonance with the heavier @xmath0-odd scalar @xmath4 .
various experiments constrain the pamela - favored nmssm parameter space , including collider searches for a light @xmath2 .
these constraints point to a unique corner of the nmssm parameter space , having a lightest neutralino mass around 160 gev and a very light pseudoscalar mass less than a gev .
a simple parameterized formula for the charge - dependent solar modulation effects reconciles the discrepancy between the pamela data and the estimated background at lower energies .
we also discuss the electron and gamma ray spectra from the fermi lat observations , and point out the discrepancy between the nmssm predictions and fermi lat preliminary results and possible resolution .
an nmssm explanation of pamela makes three striking and uniquely correlated predictions : the rise in the pamela positron spectrum will turn over at around 70 gev , the dark matter particle mass is less than the top quark mass , and a light sub - gev pseudoscalar will be discovered at colliders . .
And you have already written the first three sentences of the full article: recently , the pamela collaboration has observed an anomalous positron abundance in cosmic radiation @xcite .
the positron over electron fraction turns over and appears to rise at energies from 10 gev to 100 gev .
however , from the same detector , no obvious antiproton excess is seen for the same energy range @xcite ..
Please generate the next two sentences of the article | many suggestions have been made to explain the positron excess at pamela . among different approaches ,
dark matter annihilation is especially interesting and could imply future signals in dark matter direct detection experiments and/or at the large hadron collider ( lhc ) . in recent model - independent studies , |
5,393 | Suppose that you have an abstract for a scientific paper: in this paper we report on a monte carlo study of a diluted ising antiferromagnet on a fcc lattice .
this is a typical model example of a highly frustrated antiferromagnet , and we ask , whether sufficient random dilution of spins does produce a spin glass phase .
our data strongly indicate the existence of a spin glass transition for spin
concentration @xmath0 : we find a divergent spin glass susceptibility and a divergent spin glass correlation length , whereas the antiferromagnetic correlation length saturates in this regime .
furthermore , we find a first order phase transition to an antiferromagnet for @xmath1 , which becomes continuous in the range @xmath2 .
finite size scaling is employed to obtain critical exponents .
we compare our results with experimental systems as diluted frustrated antiferromagnets as @xmath3 . .
And you have already written the first three sentences of the full article: the family of diluted magnetic semiconductors ( dms ) of the general form @xmath4 encompasses a wide variety of alloys which have been under extensive investigation during the past 15 years .
these alloys form a zincblende structure , where the @xmath5 element occupies one fcc lattice while @xmath6 and mn share the second fcc lattice .
one fundamental aspect of research has focused on the magnetic order of these systems , since they offer practical examples of strongly frustrated , randomly diluted three dimensional fcc heisenberg antiferromagnets ( afm ) with dominant nearest neighbour interaction@xcite . in this paper we present results of a monte carlo study of a diluted frustrated ising model on a fcc lattice given by the hamiltonian @xmath7 here , @xmath8 is the coupling constant , which we will set @xmath9 henceforward , and @xmath10 $ ] is the probability that a lattice site @xmath11 is occupied with an ising .
Please generate the next two sentences of the article | spin @xmath12 .
we are interested in the static properties of this model for different dilution regimes . besides the pure ( @xmath13 ) and the slightly diluted case ( @xmath14 ) , that has already been studied by mc simulation@xcite and other methods@xcite , we concentrate our interest on the strong dilution regime , which has only been investigated in experimental heisenberg systems as mentioned above . |
5,394 | Suppose that you have an abstract for a scientific paper: helicity - dependent incoherent pion photoproduction in the reaction @xmath0 is studied in the framework of the diagrammatic approach .
contributions to the reaction amplitude from diagrams corresponding to impulse approximation as well as @xmath1 and @xmath2 interactions in the final state have been evaluated .
the elementary @xmath3 operator is taken from the maid and said models . a detailed comparison of the predictions with recent experimental data by the gdh and a2 collaborations at energies below 500 mev is presented . reasonable agreement with the data on the yields and
cross sections for polarized beam and polarized target has been achieved in all channels .
the unpolarized data of the gdh and a2 collaborations have also been analyzed within the approach .
a strong overestimation for the neutral channel has been found . at the same time
, the model provides a quite satisfactory description of the unpolarized data for the charged channels .
the sensitivity of the obtained results to the choice of the elementary @xmath3 operator is discussed in detail .
the contribution of the @xmath4 reaction to the gdh sum rule for the deuteron up to a photon energy of 1.65 gev has been evaluated with the result of @xmath5 @xmath6b . .
And you have already written the first three sentences of the full article: for more than a decade , the gdh and a2 collaborations have been carrying out intense experimental studies aimed at the verification of the famous gerasimov - drell - hearn ( gdh ) sum rule @xcite . a comprehensive overview concerning the status of these experiments
is given in ref .
@xcite ..
Please generate the next two sentences of the article | the gdh sum rule gives an integral relation between anomalous magnetic moment @xmath7 of a spin-@xmath8 particle and the difference of the total photoabsorption cross sections with parallel , @xmath9 , and antiparallel , @xmath10 , photon and target spin alignments and reads [ gdh ] s= ^_0 de _ , where @xmath11 is the photon laboratory energy , @xmath12 is the particle mass , and @xmath13
. equation ( [ gdh ] ) shows that ground - state properties given by @xmath7 and @xmath12 are related to the energy - weighted excitation spectrum of the particle . |
5,395 | Suppose that you have an abstract for a scientific paper: we give infinite lists of translations surfaces with no convex presentations .
we classify the surfaces in the stratum @xmath0 which do not have convex presentations , as well as those with no strictly convex presentations .
we show that in @xmath1 , all surfaces in the eigenform loci @xmath2 , @xmath3 or @xmath4 have no strictly convex presentation , and that the list of surfaces with no convex presentations in @xmath5 is finite and consists of square - tiled surfaces .
we prove the existence of non - lattice surfaces without strictly convex presentations in all of the strata @xmath6 .
a _ translation surface _ is a union of polygons with pairs of parallel edges identified by translation , up to cut and paste equivalence .
these structures have been intensively studied in recent years in connection with questions in group theory , geometry , complex analysis , and dynamics we recall the definitions in [ sec : general ] and refer to the recent surveys @xcite for detailed definitions and discussions of work on translation surfaces .
the cut and paste equivalence means that the same translation surface has many presentations as unions of polygons .
it is well - known ( see @xcite ) that a connected translation surface may be presented as a single polygon with an even number of edges identified pairwise .
a natural question is whether there is such a presentation , in which the polygon can be taken to be convex . in his 1992 hayashibara
forum lecture , veech @xcite was the first to exhibit surfaces with no presentations as convex polygons .
we review his examples and give new ones in [ sec : examples ] .
these include the veech double @xmath7-gons , the escher staircases , the ward examples , and the bouw - mller examples .
translation surfaces are naturally grouped in strata , which are moduli spaces of translation surfaces for which the combinatorics of singularities is fixed .
although the constructions in [ sec : examples ] yield infinitely many examples , they only give....
And you have already written the first three sentences of the full article: [ sec : general ] a _ cylinder _ for a translation surface is a topological annulus which is isometric to @xmath37 , and is not properly contained in a larger cylinder . here
@xmath38 and @xmath39 are respectively the _ height _ and _ circumference _ of the cylinder . the image of @xmath40 under such an isometry
is called a _ waist curve . _ a cylinder.
Please generate the next two sentences of the article | is always bounded by saddle connections parallel to the waist curve .
a cylinder is called _ simple _ if both of its boundary consists of a single saddle connection . [ |
5,396 | Suppose that you have an abstract for a scientific paper: one of the most important features of quantum theory is the uncertainty principle .
amount various uncertainty relations , the profound fine - grained uncertainty relation ( fgur ) is used to distinguish the uncertainty inherent in obtaining any combination of outcomes for different measurements . in this paper
, we explore this uncertainty relation in relativistic regime
. for observer undergoes an uniform acceleration who immersed in an unruh thermal bath , we show that the uncertainty bound is dependent on the acceleration parameter and choice of unruh modes .
dramatically , we find that the measurements in mutually unbiased bases ( mubs ) , sharing same uncertainty bound in inertial frame , could be distinguished from each other for a noninertial observer . on the other hand ,
once the unruh decoherence is prevented by utilizing the cavity , the entanglement could be generated from nonuniform motion .
we show that , for the observer restricted in a single rigid cavity , the uncertainty exhibits a periodic evolution with respect to the duration of the acceleration and the uncertainty bounds can be degraded by the entanglement generation during particular epoch . with properly chosen cavity parameters , the uncertainty bounds could be protected .
otherwise , the measurements in different mubs could be distinguished due to the relativistic motion of cavity .
implications of our results for gravitation and thermodynamics are discussed . .
And you have already written the first three sentences of the full article: the distinguishability of a quantum theory from its classical counterpart is formulated by the heisenberg uncertainty principle @xcite , which bounds our prediction ability for a quantum system . in terms of entropic measures
, this uncertainty relation can be recast in a modern information - theoretical form @xcite , which states that @xmath0 , where @xmath1 and @xmath2 denote the shannon entropy for the probability distribution of the measurement outcomes . since the overlap @xmath3 between observables @xmath4 and
@xmath5 does not depend on specific states to be measured , the right - hand side ( rhs ) of the inequality provides a fixed lower bound and a more general framework of quantifying uncertainty than the standard deviations @xcite ..
Please generate the next two sentences of the article | moreover , once using quantum memory to store information about the measured system , the entropic uncertainty bound could even be violated @xcite .
all these entropic uncertainty relations play an important role in many quantum information processing . |
5,397 | Suppose that you have an abstract for a scientific paper: maximally extended , explicit and regular coverings of the schwarzschild - de sitter family of vacua are given , first in spacetime ( generalizing a result due to israel ) and then for all dimensions @xmath0 ( assuming a @xmath1 sphere ) .
it is shown that these coordinates offer important advantages over the well known kruskal - szekeres procedure . .
And you have already written the first three sentences of the full article: a maximally extended and regular covering of the schwarzschild vacuum is now a fundamental part of any introduction to general relativity . almost always the covering is given by way of the implicit kruskal @xcite - szekeres @xcite procedure @xcite .
however , as emphasized long ago by ehlers @xcite , an explicit maximally extended and regular covering of the schwarzschild vacuum is known and was first given by israel @xcite . unfortunately , despite the fact that these coordinates offer many advantages over the kruskal - szekeres coordinates , they are almost never used . in this paper
i extend israel s procedure to the schwarzschild - de sitter class of vacua in four dimensions and then to arbitrary dimensions @xmath0 assuming a @xmath1 sphere as in the tangherlini generalization of the schwarzschild vacuum ..
Please generate the next two sentences of the article | moreover , it is made clear that these coordinates offer important advantages over the kruskal - szekeres procedure .
these advantages include : an explicit representation of the line element that can be extended to arbitrary dimension , a simultaneous covering of both the black hole and cosmological horizons and derivation by direct integration of einstein s equations @xcite without recourse to coordinate transformations . |
5,398 | Suppose that you have an abstract for a scientific paper: we prove knudsen s law for a gas of particles bouncing freely in a two dimensional pipeline with serrated walls consisting of irrational triangles .
dynamics are randomly perturbed and the corresponding random map studied under a skew - type deterministic representation which is shown to be ergodic and exact . * keywords : * knudsen s law , random billiards , random maps , irrational polygons , ergodic billiards . .
And you have already written the first three sentences of the full article: in his nowadays classical studies on the kinetic theory of gases , the danish physicist m. knudsen experimentally observed that , no matter how an inert gas was injected into a pipeline , the direction in which a molecule rebounds from the pipeline s solid wall is asymptotically independent of its initial trajectory .
that is , the fraction of particles leaving the surface in a given direction is proportional to @xmath0 , where @xmath1 is the angle that such a particle s trajectory defines , measured with respect to the normal to the surface ( @xcite ) .
this behaviour is referred to as the * _ knudsen s ( cosine ) law _ * ever since . in the experiment ,.
Please generate the next two sentences of the article | the gas is injected at a very low pressure so that interactions between particles are negligible .
the physical justification of knudsen s law is the following . |
5,399 | Suppose that you have an abstract for a scientific paper: there have been lots of debates about the final fate of an evaporating black hole and the singularity hidden by an event horizon in quantum gravity .
however , on general grounds , one may argue that a black hole stops radiation at the planck mass @xmath0 , where the radiated energy is comparable to the black hole s mass . and also , it has been argued that there would be a _ wormhole - like _ structure , known as space - time foam " , due to large fluctuations below the planck length @xmath1 . in this paper , as an explicit example , we consider an exact classical solution which represents nicely those two properties in a recently proposed quantum gravity model based on different scaling dimensions between space and time coordinates .
the solution , called black wormhole " , consists of two different states , depending on its mass parameter @xmath2 and an ir parameter @xmath3 : for the black hole state ( with @xmath4 ) , a _
non - traversable _ wormhole occupies the interior region of the black hole around the singularity at the origin , whereas for the wormhole state ( with @xmath5 ) , the interior wormhole is exposed to an outside observer as the black hole horizon is disappeared from evaporation .
the black hole state becomes thermodynamically stable as it approaches to the merge point where the interior wormhole throat and the black hole horizon merges , and the hawking temperature vanishes at the exact merge point ( with @xmath6 ) .
this solution suggests the generalized cosmic censorship " by the existence of a wormhole - like structure which protects the naked singularity even after the black hole evaporation .
one could understand the would - be wormhole inside the black hole horizon as the results of microscopic wormholes created by negative " energy quanta which have entered the black hole horizon in hawking radiation processes ; _ the quantum black hole could be a wormhole factory ! _
it is found that this speculative picture may be consistent with the recent @xmath7 " proposal....
And you have already written the first three sentences of the full article: this work was supported by basic science research program through the national research foundation of korea ( nrf ) funded by the ministry of education , science and technology ( 2010- 0013054 ) ( swk ) , ( 2 - 2013 - 4569 - 001 - 1 ) ( mip ) .
v. e. hubeny , phys .
d * 59 * , 064013 ( 1999 ) [ gr - qc/9808043 ] ; t. jacobson and t. p..
Please generate the next two sentences of the article | sotiriou , phys .
lett . * 103 * , 141101 ( 2009 ) [ phys . |
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