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8,800 | Suppose that you have an abstract for a scientific paper: the abelian chern simons theory is perturbed by introducing local gauge - invariant interaction terms depending on the curvature .
the computation of the correlation function @xmath0 for two smooth closed nonintersecting curves @xmath1 , @xmath2 is reported up to four loops and is shown to be unaffected by radiative corrections .
this result ensures the stability of the linking number of @xmath1 and @xmath2 with respect to the local perturbations which may be added to the chern
simons action . .
And you have already written the first three sentences of the full article: since their introduction @xcite , topological field theories have been responsible for many applications @xcite and are object of continuous investigations .
nowadays they represent an important chapter of quantum field theory .
the original motivation was related to the possibility of describing topological invariants by means of standard field - theory techniques @xcite . in order to give an idea of this framework ,.
Please generate the next two sentences of the article | let us briefly present here the field - theory characterization of one of the most simple and familiar topological invariants , namely , the linking number @xmath3 of two nonintersecting smooth closed oriented curves in @xmath4@xcite : as is well known , the linking number @xmath5 is an integer which counts the number of times that one curve winds around the other .
it is independent from the shape of the curves and can be represented by the gauss integral @xmath6 expression ( [ g - int ] ) is in fact easily seen to be an integer by use of the stokes theorem @xcite . |
8,801 | Suppose that you have an abstract for a scientific paper: we identify classical solutions of a generalised group field theory model in 3 dimensions , and study the corresponding perturbations , deriving their effective dynamics .
we discuss their interpretation as emergent matter fields .
this allows us , on the one hand to test the proposed mechanism for emergence of matter as a phase of group field theory , and on the other hand to expose some limitations of the generalised group field theory formalism . .
And you have already written the first three sentences of the full article: in the last decades several approaches to quantum gravity have been developed , with important results @xcite . among them , group field theories ( gft ) @xcite are , in our opinion , particularly promising .
gfts are quantum field theories defined over a group manifold , representing a meta - spaceof discrete spacetime geometries , and not spacetime itself , as a new algebraic and combinatorial realization of the third quantizationidea @xcite .
moreover , gfts bring together most of the ingredients entering in other _.
Please generate the next two sentences of the article | non perturbative _ and _ background independent _ approaches ( such as loop quantum gravity , spin foam models and simplicial quantum gravity approaches ) @xcite .
very little is known , still , about group field theory models for quantum gravity , in both 3 and 4 dimensions , and a lot of technical work should go into their analysis , for example their classical solutions , which will be one focus of the present work , and their purely field theoretic aspects , which are the subject of attention at present @xcite . |
8,802 | Suppose that you have an abstract for a scientific paper: we introduce a new set of symmetries obeyed by tree - level gauge - theory amplitudes involving at least one gluon
. the symmetry acts as a momentum - dependent shift on the color factors of the amplitude . using the radiation vertex expansion , we prove the invariance under this color - factor shift of the @xmath0-gluon amplitude , as well as amplitudes involving massless or massive particles in an arbitrary representation of the gauge group with spin zero , one - half , or one .
the bern - carrasco - johansson relations are a direct consequence of this symmetry .
we also introduce the cubic vertex expansion of an amplitude , and use it to derive a gauge - invariant constraint on the kinematic numerators of the amplitude .
we show that the amplitudes of the bi - adjoint scalar theory are invariant under the color - factor symmetry , and use this to derive the null eigenvectors of the propagator matrix .
we generalize the color - factor shift to loop level , and prove the invariance under this shift of one - loop @xmath0-gluon amplitudes in any theory that admits a color - kinematic - dual representation of numerators .
we show that the one - loop color - factor symmetry implies known relations among the integrands of one - loop color - ordered amplitudes .
bow - ph-162 + mctp-16 - 17 + * bcj relations from a new symmetry of gauge - theory amplitudes * 1.5 cm robert w. brown@xmath1 and stephen g. naculich@xmath2 0.5 cm @xmath1_department of physics + case western reserve university + cleveland , oh 44106 usa _ 0.5 cm @xmath3_department of physics + bowdoin college + brunswick , me 04011 usa _ 0.5 cm @xmath4_michigan center for theoretical physics ( mctp ) + department of physics + university of michigan + ann arbor , mi 48109 usa
_ 1.5 cm .
And you have already written the first three sentences of the full article: in 2008 , bern , carrasco , and johansson discovered a novel set of linear relations satisfied by tree - level color - ordered amplitudes in gauge theories@xcite .
they arrived at these relations by writing the tree - level @xmath0-gluon amplitude as a sum over @xmath5 diagrams assembled from cubic vertices = _ i c_i n_i d_i [ cubicdecompintro ] where the color factor @xmath6 associated with the diagram is composed of group theory structure constants @xmath7 , the denominator @xmath8 consists of the product of the inverse propagators associated with the diagram , and the kinematic numerator @xmath9 depends on the momenta and polarizations of the gluons .
all contributions from diagrams with quartic vertices are redistributed among the cubic diagrams . by virtue of the jacobi identity.
Please generate the next two sentences of the article | @xmath10 satisfied by the structure constants , the color factors @xmath6 obey a set of jacobi relations of the form c_i + c_j + c_k = 0 . because of these linear dependences , the kinematic numerators @xmath9 are not uniquely defined , but can undergo _ generalized gauge transformations _ @xmath11 which leave unchanged @xcite .
the authors of ref . |
8,803 | Suppose that you have an abstract for a scientific paper: _ zero forcing number _ , @xmath0 , of a graph @xmath1 is the minimum cardinality of a set @xmath2 of black vertices ( whereas vertices in @xmath3 are colored white ) such that @xmath4 is turned black after finitely many applications of the color - change rule " : a white vertex is converted black if it is the only white neighbor of a black vertex .
zero forcing number was introduced and used to bound the minimum rank of graphs by the
aim minimum rank special graphs work group " .
let @xmath5 and @xmath6 be disjoint copies of a graph @xmath1 and let @xmath7 be a function . then a _ functigraph _
@xmath8 has the vertex set @xmath9 and the edge set @xmath10 . for a connected graph @xmath1 of order @xmath11 , it is readily seen that @xmath12 for any permutation @xmath13 ; we show that @xmath14 for any function @xmath15 , where @xmath16 is the minimum degree of @xmath1 .
we give examples showing that there does not exist a function @xmath17 such that , for every pair @xmath18 , @xmath19 or @xmath20 .
we further investigate the zero forcing number of functigraphs on complete graphs , on cycles , and on paths .
zero forcing set , zero forcing number , permutation graph , generalized prism , functigraph , complete graph , cycle , path 05c50 , 05c38 , 05d99 + .
And you have already written the first three sentences of the full article: let @xmath21 be a finite , simple , connected , and undirected graph of order @xmath22 . for a given graph @xmath1 and @xmath23 , we denote by @xmath24 the subgraph induced by @xmath2 . for a vertex @xmath25 ,
the _ open neighborhood of @xmath26 _ is the set @xmath27 and the _ closed neighborhood of @xmath26 _ is the set @xmath28=n_g(v ) \cup \{v\}$ ] .
the _ degree _ @xmath29 of a vertex @xmath25 is the the number of edges incident with the vertex @xmath26 in @xmath1 ..
Please generate the next two sentences of the article | we denote by @xmath16 the _ minimum degree _ of a graph @xmath1 .
the _ distance _ between two vertices @xmath30 , denoted by @xmath31 , is the length of the shortest path between @xmath26 and @xmath32 . for other terminologies in graph theory , |
8,804 | Suppose that you have an abstract for a scientific paper: we consider dynamic subgraph connectivity problems for planar undirected graphs . in this model
there is a fixed underlying planar graph , where each edge and vertex is either `` off '' ( failed ) or `` on '' ( recovered ) . we wish to answer connectivity queries with respect to the `` on '' subgraph .
the model has two natural variants , one in which there are @xmath0 edge / vertex failures that precede all connectivity queries , and one in which failures / recoveries and queries are intermixed .
we present a @xmath0-failure connectivity oracle for planar graphs that processes any @xmath0 edge / vertex failures in @xmath1 time so that connectivity queries can be answered in @xmath2 time .
( here @xmath3 and @xmath4 are the time for integer sorting and integer predecessor search over a subset of @xmath5 $ ] of size @xmath0 . )
our algorithm has two discrete parts .
the first is an algorithm tailored to triconnected planar graphs .
it makes use of barnette s theorem , which states that every triconnected planar graph contains a degree-3 spanning tree .
the second part is a generic reduction from general ( planar ) graphs to triconnected ( planar ) graphs .
our algorithm is , moreover , provably optimal .
an implication of ptracu and thorup s lower bound on predecessor search is that no @xmath0-failure connectivity oracle ( even on trees ) can beat @xmath2 query time .
we extend our algorithms to the subgraph connectivity model where edge / vertex failures ( but no recoveries ) are intermixed with connectivity queries . in triconnected planar graphs
each failure and query is handled in @xmath6 time ( amortized ) , whereas in general planar graphs both bounds become @xmath7 . .
And you have already written the first three sentences of the full article: algorithms for dynamic graphs have traditionally assumed that the graph evolves according to a completely arbitrary sequence of insertions and deletions of graph elements .
this model makes minimal assumptions but often sacrifices efficiency for generality .
for example , real world networks ( router networks , road networks , etc . ) _ do _ change slowly over time ..
Please generate the next two sentences of the article | however , the real dynamism of the networks comes from the frequent _ failure _ of edges / nodes and their subsequent recovery . in this paper
we study connectivity problems in the _ dynamic subgraph model _ , which attempts to accurately model this type of dynamism . |
8,805 | Suppose that you have an abstract for a scientific paper: we consider a model of semi - flexible interacting self - avoiding trails ( sisat s ) on a lattice , where the walks are constrained to visit each lattice edge at most once .
such models have been studied as an alternative to the self - attracting self - avoiding walks ( sasaw ) to investigate the collapse transition of polymers , with the attractive interactions being on site , as opposed to nearest - neighbor interactions in sasaw .
the grand - canonical version of the sisat model is solved on a four - coordinated bethe lattice , and four phases appear : non - polymerized ( * np * ) , regular polymerized ( * p * ) , dense polymerized ( * dp * ) and anisotropic nematic ( * an * ) , the last one present in the phase diagram only for sufficiently stiff chains . the last two phases are dense , in the sense that all lattice sites are visited once in * an * phase and twice in * dp * phase . in general ,
critical * np*-*p * and * dp*-*p * transition surfaces meet with a * np*-*dp * coexistence surface at a line of bicritical points .
the region in which the * an * phase is stable is limited by a _ discontinuous critical _ transition to the * p * phase , and we study this somewhat unusual transition in some detail . in the limit of rods , where the chains are totally rigid , the * p * phase is absent and the three coexistence lines ( * np*-*an * , * an*-*dp * , and * np*-*dp * ) meet at a triple point , which is the endpoint of the bicritical line . .
And you have already written the first three sentences of the full article: in the most studied lattice model for the collapse transition ( also called coil - globule transition ) of polymers @xcite , the chains are represented by self - avoiding walks , so that the bonds of the chain are placed on lattice edges and the monomers are located on the sites .
an attractive interaction between monomers on nearest - neighbor sites which are not linked by bonds is added .
the competition between the repulsive excluded - volume interactions and the attractive interactions leads to a change in the polymerization transition of sasaw ( self - attracting self - avoiding walks ) in a grand - canonical formalism ..
Please generate the next two sentences of the article | experimentally , as the temperature of a polymer solution is lowered , the chain changes its configuration from extended ( coil ) to collapsed ( globule ) , as the temperature crosses a particular value , called the @xmath0-point . for weak attraction ,
the transition between a non - polymerized and a polymerized phase in the monomer fugacity - temperature plane is continuous , becoming discontinuous as the attraction is increased , so that the collapse transition is a tricritical point in this model . |
8,806 | Suppose that you have an abstract for a scientific paper: we discuss the impact of special relativistic effects on the observed light curves and variability duty cycles of radio - loud active galactic nuclei ( agns ) .
we model the properties of agn light curves at radio wavelengths using a simulated shot noise process in which the occurrence of major flaring events in a relativistic jet is governed by poisson statistics .
we show that flaring sources whose radiation is highly beamed toward us are able to reach very high flux levels , but will in fact spend most of their time in relatively low flaring states .
this is primarily due to relativistic doppler contraction of flaring time scales in the observer frame .
the fact that highly beamed agns are not observed to return to a steady - state quiescent level between flares implies that their weakly beamed counterparts should have highly stable flux densities that result from a superposition of many long - term , low - amplitude flares .
the `` apparent '' quiescent flux levels of these weakly beamed agns ( identified in many unified models as radio galaxies ) will be significantly higher than their true quiescent ( i.e. , non - flaring ) flux levels .
we have also performed monte carlo simulations to examine how relativistic beaming and source variability bias the selection statistics of flat - spectrum agn samples .
we find that in the case of the caltech - jodrell flat - spectrum survey ( cj - f ) , the predicted orientation bias towards jets seen end - on is weakened if the parent population is variable , since the highly beamed sources have a stronger tendency to be found in low flaring states .
this effect is small , however , due to the fact that highly beamed sources are relatively rare , and in most cases their flux densities will be boosted sufficiently above the survey limit such that they will be selected regardless of their flaring level .
we find that for larger flat - spectrum agn surveys with fainter flux density cutoffs , variability should not be an appreciable source of selection bias . .
And you have already written the first three sentences of the full article: one of the hallmarks of flat - spectrum radio - loud active galactic nuclei ( agns ) is their tendency to display large flux density variations over a wide range of wavelengths .
studies of complete agn samples ( e.g. , @xcite ) have shown that the degree of variability at radio wavelengths is well - correlated with the prominence of a bright , flat - spectrum core component that is thought to harbor the supermassive black hole and accretion disk that power the agn .
parsec - scale images made with vlbi techniques show that this core is usually located at the base of a highly collimated , relativistic outflow ..
Please generate the next two sentences of the article | the extremely high speeds of agn jets are responsible for numerous biases in the observed properties of samples selected on the basis of core flux density , due to special relativistic effects ( e.g. , @xcite ) .
for example , the distribution of source orientations in such samples will be heavily weighted towards jets seen nearly end - on , due to relativistic beaming of radiation in the direction of motion . |
8,807 | Suppose that you have an abstract for a scientific paper: in this work , angular distribution measurements for the elastic channel were performed for the @xmath0be+@xmath1c reaction at the energies e@xmath2=13.0 , 14.5 , 17.3 , 19.0 and 21.0 mev , near the coulomb barrier .
the data have been analyzed in the framework of the double folding so paulo potential .
the experimental elastic scattering angular distributions were well described by the optical potential at forward angles for all measured energies . however , for the three highest energies , an enhancement was observed for intermediate and backward angles .
this can be explained by the elastic transfer mechanism .
@xmath0be+@xmath1c , elastic scattering , so paulo potential 24.10 .
And you have already written the first three sentences of the full article: in the last few years , nuclear reactions involving weakly bound nuclei became a subject of interest due to the observation of flux enhancement for processes like nucleon transfer and breakup . through the study of these processes @xcite , it is possible to obtain information about nuclear structure , such as single - particle states and nuclear cluster structure , as well as information about the influence of continuum states in the nuclear reaction dynamics @xcite . additionally , the investigation on how these properties change from the stability line to regions far from the stability valley can also be addressed .
in this context , the elastic scattering measurement and coupled channel analysis @xcite are very important tools to investigate nucleon transfer and breakup , as they appear as competing mechanisms in the reproduction of the measured angular distributions . in this work , elastic scattering cross section measurements were performed for the @xmath3be+@xmath1c reaction to study anomalies @xcite in the extracted optical parameters values and the contribution of inelastic channels , transfer and compound nucleus formation in the elastic scattering process .
the experimental data show an enhancement in the elastic cross sections at intermediate and backward angles . this behavior is typically observed in systems where projectile and target present the same core structure @xcite ..
Please generate the next two sentences of the article | this effect can be understood in terms of a @xmath4he transfer process , assuming that @xmath1c has a @xmath4he+@xmath0be cluster structure .
the elastic scattering angular distributions were analyzed in a four steps procedure . |
8,808 | Suppose that you have an abstract for a scientific paper: a new high - order conservative finite element method for darcy flow is presented .
the key ingredient in the formulation is a volumetric , residual - based , based on lagrange multipliers in order to impose conservation of mass that does not involve any mesh dependent parameters .
we obtain a method with high - order convergence properties with locally conservative fluxes .
furthermore , our approach can be straightforwardly extended to three dimensions .
it is also applicable to highly heterogeneous problems where high - order approximation is preferred . .
And you have already written the first three sentences of the full article: many porous media related practical problems lead to the numerical approximation of the pressure equation @xmath0 where @xmath1 is the part of the boundary of the domain @xmath2 ( denoted by @xmath3 ) where the dirichlet boundary condition is imposed . in case
the measure of @xmath1 ( denoted by @xmath4 ) is zero , we assume the compatibility condition @xmath5 . on the above equation
we have assumed without loss of generality homogenous boundary conditions since we can always reduce the problem to that case ..
Please generate the next two sentences of the article | the domain @xmath2 is assumed to be a convex polygonal region .
we note however that this convexity is not required for the discretization , it is required only when regularity theory of partial differential equations ( pdes ) is considered for establishing the a priori error estimates . |
8,809 | Suppose that you have an abstract for a scientific paper: we have obtained high spectral resolution ( r = 45900 ) fabry - perot velocity maps of the hickson compact group hcg 31 in order to revisit the important problem of the merger nature of the central object a+c and to derive the internal kinematics of the candidate tidal dwarf galaxies in this group .
our main findings are : ( 1 ) double kinematic components are present throughout the main body of a+c , which strongly suggests that this complex is an ongoing merger ( 2 ) regions @xmath0 and e , to the east and south of complex a+c , present rotation patterns with velocity amplitudes of @xmath1 and they counterrotate with respect to a+c , ( 3 ) region f , which was previously thought to be the best example of a tidal dwarf galaxy in hcg 31 , presents no rotation and negligible internal velocity dispersion , as is also the case for region @xmath2 .
hcg 31 presents an undergoing merger in its center ( a+c ) and it is likely that it has suffered additional perturbations due to interactions with the nearby galaxies b , g and q. .
And you have already written the first three sentences of the full article: the spectacular hickson compact group 31 ( hickson 1982 ) shows a wide range of indicators of galaxy interaction and merging : tidal tails , irregular morphology , complex kinematics , vigourous star bursting ( e.g. rubin et al . 1990 ) and possible formation of tidal dwarf galaxies ( e.g. hunberger et al .
all the objects belonging to the group are embedded in a common large hi envelope ( williams et al .
the group is formed by members a+c , b , e , f , g , q ( rubin et al . 1990 ) ..
Please generate the next two sentences of the article | two scenarios have been put forward to explain the nature of the central system a+c : it is either two systems that are about to merge ( e.g. rubin et al . 1990 ) or a single interacting galaxy ( richer et al .
2003 ) . in this letter |
8,810 | Suppose that you have an abstract for a scientific paper: a new type of compact stellar systems , labelled `` ultra - compact dwarf galaxies '' ( ucds ) , was discovered in the last decade .
recent studies show that their dynamical mass - to - light ratios ( m / l ) tend to be too high to be explained by canonical stellar populations , being on average about twice as large as those of galactic globular clusters of comparable metallicity .
if this offset is caused by dark matter in ucds , it would imply dark matter densities as expected for the centers of cuspy dark matter halos , incompatible with cored dark matter profiles . investigating
the nature of the high m / l ratios in ucds therefore offers important constraints on the phase space properties of dark matter particles .
here we describe an observational method to test whether a bottom - heavy imf may cause the high m / l ratios of ucds .
we propose to use the co index at 2.3@xmath0 which is sensitive to the presence of low - mass stars to test for a bottom heavy imf . in the case that the high m / l ratios are caused by a bottom - heavy imf , we show that the equivalent width of the co index will be up to 30% weaker in ucds compared to sources with similar metallicity that have canonical imfs .
we find that these effects are well detectable with current astronomical facilities in a reasonable amount of time ( a few hours to nights ) .
measuring the co index of ucds hence appears a promising tool to investigate the origin of their high m / l ratios . .
And you have already written the first three sentences of the full article: within the last decade , a new class of compact stellar systems has been discovered : the so - called `` ultra - compact dwarf galaxies '' ( ucds , phillips et al .
2001 ; see also hilker et al .
1999 ; drinkwater et al ..
Please generate the next two sentences of the article | 2000 & 2003 ; mieske et al .
2004 , 2006 , 2007 ; haegan et al . |
8,811 | Suppose that you have an abstract for a scientific paper: proper motions with values @xmath0 mas yr@xmath1 or @xmath2 mas yr@xmath1 have been extracted from the usno - b1.0 and tycho ii catalogues for all lanning uv - bright sources identified in the sandage two - color survey of the galactic plane and presented in papers i - vi . of the 572 sources examined , we find at least 213 which exhibit a significantly large proper motion . based on the location of the sources in a reduced proper motion diagram , we demonstrate that about two thirds of the high proper motion sources are likely or very likely to be heretofore unidentified white dwarfs . .
And you have already written the first three sentences of the full article: to date , seven papers have been published providing listings and finding charts for faint uv - bright sources identified on plates from the sandage two - color survey of the galactic plane .
the most recently published paper , paper vii ( @xcite ) , included proper motions for many of the sources found using information extracted from the usno - b1.0 catalog @xcite .
the combination of the magnitude , color and proper motion values available for these sources provides important additional data that may lead to the detection of previously unidentified white dwarfs ..
Please generate the next two sentences of the article | the usno - b1.0 catalogue was not available prior to publication of paper vii .
therefore , it was considered worthwhile to go back and examine all previously identified lanning uv - bright sources in hopes of finding additional evidence to identify the best candidates for new white dwarfs in the published catalogues . as noted in the previous papers devoted to this survey project , the sandage two - color survey consists of more than 100 plates measuring 6.6 degrees on a side and centered on the galactic plane . |
8,812 | Suppose that you have an abstract for a scientific paper: we study partially and totally associative ternary algebras of first and second kind . assuming the vector space underlying a ternary algebra to be a topological space and a triple product to be continuous mapping we consider the trivial vector bundle over a ternary algebra and
show that a triple product induces a structure of binary algebra in each fiber of this vector bundle .
we find the sufficient and necessary condition for a ternary multiplication to induce a structure of associative binary algebra in each fiber of this vector bundle .
given two modules over the algebras with involutions we construct a ternary algebra which is used as a building block for a lie algebra .
we construct ternary algebras of cubic matrices and find four different totally associative ternary multiplications of second kind of cubic matrices .
it is proved that these are the only totally associative ternary multiplications of second kind in the case of cubic matrices .
we describe a ternary analog of lie algebra of cubic matrices of second order which is based on a notion of @xmath0-commutator and find all commutation relations of generators of this algebra . 17a40 , 20n10 .
[ firstpage ] .
And you have already written the first three sentences of the full article: a ternary algebra or triple system is a vector space @xmath1 endowed with a ternary law of composition @xmath2 which is a linear mapping with respect to each its argument , and we will call this mapping a ternary multiplication or triple product of a ternary algebra @xmath1 .
hence a ternary algebra is an algebra which closes under a suitable triple product .
obviously any binary algebra which closes under double product can be considered as a ternary algebra if one defines the ternary multiplication as twice successively applied binary one , and in this case the ternary multiplication is generated by a binary one ..
Please generate the next two sentences of the article | however there are ternary multiplications which can not be obtained as twice successively applied binary multiplication .
for instance , pure imaginary numbers or elements of grading one of a superalgebra closes under triple product . |
8,813 | Suppose that you have an abstract for a scientific paper: hybrid quantum information protocols are based on local qubits , such as trapped atoms , nv centers , and quantum dots , coupled to photons .
the coupling is achieved through optical cavities . here
we demonstrate far - field optimized h1 photonic crystal membrane cavities combined with an additional back reflection mirror below the membrane that meet the optical requirements for implementing hybrid quantum information protocols . using numerical optimization
we find that 80@xmath0 of the light can be radiated within an objective numerical aperture of 0.8 , and the coupling to a single - mode fiber can be as high as 92@xmath0 .
we experimentally prove the unique external mode matching properties by resonant reflection spectroscopy with a cavity mode visibility above 50@xmath0 .
[ 1][1]#1 10 k. j. vahala , `` optical microcavities , '' nature * 424 * , 839846 ( 2003 ) .
b. lounis and m. orrit , `` single - photon sources , '' rep .
. phys . * 68 * , 11291179 ( 2005 ) .
s. strauf , n. g. stoltz , m. t. rakher , l. a. coldren , p. m. petroff , and d. bouwmeester , `` high - frequency single - photon source with polarization control , '' nat . photon . * 1 * , 704708 ( 2007 ) .
s. reitzenstein and a. forchel , `` quantum dot micropillars , '' j. phys .
d : appl .
phys . * 43 * , 033001 ( 2010 ) .
m. larqu@xmath1 , t. karle , i. robert - philip , and a. beveratos , `` optimizing h1 cavities for the generation of entangled photon pairs , '' new j. phys .
* 11 * , 033022 ( 2009 ) .
p.
k. pathak and s. hughes , `` cavity - assisted fast generation of entangled photon pairs through the biexiton - exiton cascade , '' phys .
rev .
b * 80 * , 155325 ( 2009 ) .
s. m. de vasconcellos , a. calvar , a. dousse , j. suffczy@xmath2ski , n. dupuis , a. lema@xmath3tre , i. sagnes , j. bloch , p. voisin , and p. senellart , `` spatial , spectral , and polarization properties of coupled micropillar cavities , '' appl .
. lett . * 99 * ,....
And you have already written the first three sentences of the full article: semiconductor quantum dots ( qds ) coupled to optical microcavities have been extensively studied as a solid - state system for cavity quantum electrodynamics ( c - qed ) and as a promising platform to implement quantum information processing protocols involving single photons and single electron spins@xcite .
efficient single photon sources have been demonstrated@xcite , and the generation of polarization entangled photons has been proposed@xcite and demonstrated@xcite .
quantum information protocols employing c - qed require the implementation of a spin - photon interface , to optically read - out the spin state@xcite and to deterministically generate spin - photon entanglement@xcite . for these schemes and others , the cavity needs to be polarization degenerate and there needs to be good mode - matching between the input light field and the field radiated by the atom@xcite ..
Please generate the next two sentences of the article | planar photonic crystal ( phc ) microcavities are widely studied because of their small mode volumes , @xmath10 , and high quality factors , q @xmath11@xcite .
in - plane confinement is achieved by the photonic band gap introduced by the air holes etched in a high - index membrane , while out - of - plane confinement relies on total internal reflection at the membrane - air interface . |
8,814 | Suppose that you have an abstract for a scientific paper: supernovae are the most energetic stellar events and influence the interstellar medium by their gasdynamics and energetics . by this ,
both also affect the star formation positively and negatively . in this paper , we review the development of the complexity of investigations aiming at understanding the interchange between supernovae and their released hot gas with the star - forming molecular clouds . commencing from analytical studies
the paper advances to numerical models of supernova feedback from superbubble scales to galaxy structure .
we also discuss parametrizations of star - formation and supernova - energy transfer efficiencies .
since evolutionary models from the interstellar medium to galaxies are numerous and apply multiple recipes of these parameters , only a representative selection of studies can be discussed here .
2/pc^2 a&a .
And you have already written the first three sentences of the full article: since stars are formed within the coolest molecular material of the interstellar medium ( ism ) , the star - formation rate ( sfr ) should be determined simply by the gas reservoir and by the free - fall time @xmath0 of molecular clouds ( @xcite ) .
this , however , raises a conflict between the ism conditions and observed sfrs in the sense that @xmath0 for a typical molecular cloud density of 100 @xmath1 amounts to 10@xmath2 sec , i.e. @xmath3 yrs . for
the total galactic molecular mass of @xmath4 the sfr should then amount to about 100 to 1000 , what is by orders of magnitudes larger than observed and the gas reservoir within the milky way would have been used up today ..
Please generate the next two sentences of the article | this means , that the sf timescale must be stretched with respect to collapse or dynamical timescale by introducing a sf efficiency ( sfe ) @xmath5 and its definition could read : @xmath6 . already in 1959
schmidt argued that the sfr per unit area is related to the gas column density @xmath7 by a power law with exponent @xmath8 . |
8,815 | Suppose that you have an abstract for a scientific paper: the phenomenology of a newly developed model of hybrid meson decay is developed .
the decay mechanism is based on the heavy quark expansion of qcd and the strong coupling flux tube picture of nonperturbative glue .
a comprehensive list of partial decay widths of a wide variety of light , @xmath0 , @xmath1 , and @xmath2 hybrid mesons is presented .
results which appear approximately universal are highlighted along with those which distinguish different hybrid decay models .
finally , we examine several interesting hybrid candidates in detail .
# 1 .
And you have already written the first three sentences of the full article: quantum chromodynamics at low energy remains enigmatic chiefly because of an almost complete lack of knowledge of the properties of soft glue .
glue must certainly be understood if phenomena such as color confinement , mass generation , and dynamical symmetry breaking are to be understood .
the discovery and explication of hadrons with excited gluonic degrees of freedom is clearly an important step in this process ..
Please generate the next two sentences of the article | furthermore , the search for nonperturbative glue , in particular as manifested in hybrid mesons , would be greatly facilitated by a rudimentary knowledge of the hybrid spectrum and decay characteristics .
although it appears that lattice estimates of light quenched hybrid masses are forthcoming@xcite , hadronic decays remain difficult to calculate on the lattice . |
8,816 | Suppose that you have an abstract for a scientific paper: the spin precession in a cylindrical semiconductor nanowire due to rashba spin - orbit coupling has been investigated theoretically using an inas nanowire containing a surface two - dimensional electron gas as a model .
the eigenstates , energy - momentum dispersion , and the energy - magnetic field dispersion relation are determined by solving the schrdinger equation in a cylindrical symmetry . the combination of states with the same total angular momentum but opposite spin orientation results in a periodic modulation of the axial spin component along the axis of the wire .
spin - precession about the wires axis is achieved by interference of two states with different total angular momentum .
because a superposition state with exact opposite spin precession exists at zero magnetic field , an oscillation of the spin orientation can be obtained .
if an axially oriented magnetic field is applied , the spin gains an additional precessing component . .
And you have already written the first three sentences of the full article: semiconductor nanowires are almost ideal objects for studying quantum effects and electron interference phenomena .
the use of the bottom - up approach for nanowire growth simplifies the preparation substantially and allows us to create novel confinement schemes , such as axial or radial heterostructures.@xcite the large surface - to - volume ratio of nanowires means that surface properties are crucial for discussions of transport properties , so that low band - gap semiconductors , e.g. inas , inn , or insb , are particularly interesting . in these systems ,
the fermi level at the surface is pinned inside the conduction band,@xcite and an accumulation layer is formed ..
Please generate the next two sentences of the article | this guarantees that the conductance is sufficiently large even at low nanowire radius .
the presence of the surface accumulation layer means that a tubular conducting channel is formed , and this shape of the conductor has important implications for the magnetoconductance of the nanowires . |
8,817 | Suppose that you have an abstract for a scientific paper: we introduce a new statistical method to estimate the primordial helium abundance @xmath0 from observed abundances in a sample of galaxies which have experienced stellar helium enrichment . rather than using linear regression on metal abundance
we construct a likelihood function using a bayesian prior , where the key assumption is that the true helium abundance must always exceed the primordial value . using a sample of measurements compiled from the literature we find estimates of @xmath0 between 0.221 and 0.236 , depending on the specific subsample and prior adopted , consistent with previous estimates either from a linear extrapolation of the helium abundance with respect to metallicity , or from the helium abundance of the lowest metallicity region , i zw 18 .
we also find an upper limit which is insensitive to the specific subsample or prior , and estimate a model - independent bound @xmath1 at 95% confidence , favoring a low cosmic baryon density and a high primordial deuterium abundance .
the main uncertainty is not the model of stellar enrichment but possible common systematic biases in the estimate of @xmath2 in each individual hii region .
# 1 # 1 -.2 in .
And you have already written the first three sentences of the full article: big bang nucleosynthesis ( bbn ) makes a clean prediction for the primordial helium abundance @xmath0 , depending on only one parameter ( the baryon - to - photon ratio @xmath3 ) and on that only weakly .
a precise measurement of @xmath0 is therefore necessary to test bbn even in the present situation where measurements of other predicted quantities constraining @xmath3 , such as the primordial lithium abundance , deuterium abundance and the cosmic baryon density , are not yet so precise ( e.g. walker 1991 , smith 1993 , sarkar 1996 , fields 1996 , hogan 1997ab ) .
even though the bulk of the helium of the universe originates in the big bang , the additional helium enrichment by stars can not be ignored in estimating the primordial abundance from observations of present - day helium . unlike the case of deuterium.
Please generate the next two sentences of the article | , we do not have the option of measuring directly the nearly primordial abundance of 4 at high redshift .
lyman-@xmath4 absorption by he@xmath5 at high redshift now gives a rough direct estimate of primordial abundance ( hogan , anderson & rugers 1997 ) , but require uncertain ionization corrections to estimate @xmath2 . |
8,818 | Suppose that you have an abstract for a scientific paper: machine learning ( ml ) techniques are indispensable in a wide range of fields .
unfortunately , the exponential increase of dataset sizes are rapidly extending the runtime of sequential algorithms and threatening to slow future progress in ml . with the promise of affordable large - scale parallel computing ,
cloud systems offer a viable platform to resolve the computational challenges in ml .
however , designing and implementing _ efficient _ , _ provably correct _ distributed ml algorithms is often prohibitively challenging .
to enable ml researchers to easily and efficiently use parallel systems , we introduced the graphlab abstraction which is designed to represent the computational patterns in ml algorithms while permitting efficient parallel and distributed implementations . in this paper
we provide a formal description of the graphlab parallel abstraction and present an efficient distributed implementation .
we conduct a comprehensive evaluation of graphlab on three state - of - the - art ml algorithms using real large - scale data and a 64 node ec2 cluster of 512 processors . we find that graphlab achieves orders of magnitude performance gains over hadoop while performing comparably or superior to hand - tuned mpi implementations . .
And you have already written the first three sentences of the full article: with the exponential growth in machine learning ( ml ) datasets sizes and increasing sophistication of ml techniques , there is a growing need for systems that can execute ml algorithms efficiently in parallel on large clusters .
unfortunately , based on our comprehensive survey , we find that existing popular high level parallel abstractions , such as mapreduce @xcite and dryad @xcite , do not efficiently fit many ml applications .
alternatively , designing , implementing , and debugging ml algorithms on low level frameworks such as openmp @xcite or mpi @xcite can be excessively challenging , requiring the user to address complex issues like race conditions , deadlocks , and message passing in addition to the already challenging mathematical code and complex data models common in ml research . in this paper.
Please generate the next two sentences of the article | we describe the culmination of two years of research in collaboration with ml , parallel computing , and distributed systems experts . by focusing on machine learning we designed graphlab , a domain specific parallel abstraction @xcite that fits the needs of the ml community , without sacrificing computational efficiency or requiring ml researchers to redesign their algorithms . in @xcite
we first introduced the graphlab multi - core api to the ml community . in this paper |
8,819 | Suppose that you have an abstract for a scientific paper: the evolution of a system of chemical reactions can be studied , in the eikonal approximation , by means of a hamiltonian dynamical system .
the fixed points of this dynamical system represent the different states in which the chemical system can be found , and the connections among them represent instantons or optimal paths linking these states .
we study the relation between the phase portrait of the hamiltonian system representing a set of chemical reactions with constant rates and the corresponding system when these rates vary in time .
we show that the topology of the phase space is robust for small time - dependent perturbations in concrete examples and state general results when possible .
this robustness allows us to apply some of the conclusions on the qualitative behavior of the autonomous system to the time - dependent situation . .
And you have already written the first three sentences of the full article: understanding the dynamics of chemical kinetics is a question of fundamental character in nonequilibrium statistical mechanics , apart from being of broad importance in applications to other sciences . indeed , many models in chemistry @xcite , biochemistry @xcite , ecology @xcite , and biology @xcite use stoichiometric relations as theoretical first principles describing some phenomenon . the simplest description of the time evolution of a set of @xmath0 reacting species is probably given by the mean - field equations , an @xmath1dimensional dynamical system representing the concentrations , or total number of molecules of the reacting species .
one of the advantages of this approach is that it allows us to use the powerful machinery of dynamical systems theory @xcite , raising the possibility of identifying stationary states with fixed points , periodic behavior with limit cycles , etc . of course
, as with every theory in physics , the mean - field approximation has a range of validity ..
Please generate the next two sentences of the article | as it ignores fluctuations , its description of the chemical system might be accurate for short times ; however , long - time dynamics will be affected , dramatically in some cases , by rare events .
it is possible to study exactly the system evolution as a time - continuous markov process , the probability distribution of which is given by the solution of an adequate master equation @xcite . |
8,820 | Suppose that you have an abstract for a scientific paper: we present 30 ghz measurements of the angular power spectrum of the cosmic microwave background ( cmb ) obtained with the sunyaev - zeldovich array .
the measurements are sensitive to arcminute angular scales , where secondary anisotropy from the sunyaev - zeldovich effect ( sze ) is expected to dominate . for a broad bin centered at multipole 4066
we find @xmath0 , of which @xmath1 is the expected contribution from primary cmb anisotropy and @xmath2 is the expected contribution from undetected radio sources .
these results imply an upper limit of 155@xmath3 ( 95% cl ) on the secondary contribution to the anisotropy in our maps .
this level of sze anisotropy power is consistent with expectations based on recent determinations of the normalization of the matter power spectrum , i.e. , @xmath4 . .
And you have already written the first three sentences of the full article: density perturbations at the epoch of recombination are imprinted onto the cosmic microwave background ( cmb ) , leaving temperature anisotropy that has now been well - studied on a wide range of angular scales . on scales of several arcminutes and smaller , corresponding to multipole moments of @xmath5 , the level of cmb anisotropy power from primordial fluctuations
is strongly suppressed by photon diffusion , and secondary sources of power , including the sunyaev - zeldovich effect ( sze ) , are expected to play a significant role ( e.g. , * ? ? ?
the sze results from the inverse compton scattering of cmb photons by the hot electron gas within clusters of galaxies @xcite ..
Please generate the next two sentences of the article | this interaction leaves a small spectral distortion in the cmb which produces anisotropy power on scales of @xmath6 , detectable as a decrement in the cmb intensity at 30 ghz .
the amplitude of this power is extremely sensitive to the history of structure formation and , specifically , to the value of @xmath7 , the normalization of the matter power spectrum ( e.g. , * ? ? ? |
8,821 | Suppose that you have an abstract for a scientific paper: each ruling of a legendrian link can be naturally treated as a surface . for knots ,
the ruling is @xmath0graded if and only if the surface is orientable . for @xmath0graded rulings of homogeneous ( in particular , alternating ) knots ,
we prove that the genus of this surface is at most the genus of the knot . while this is not true in general
, we do prove that the canonical genus ( a.k.a .
diagram genus ) of any knot is an upper bound for the genera of its @xmath0graded rulings . .
And you have already written the first three sentences of the full article: a _ legendrian knot _ in @xmath1 is a smooth embedding of @xmath2 that is always tangent to the @xmath0planes of the so - called _ standard contact structure _ @xmath3 , and a _ link _ is a finite disjoint union of knots .
we consider legendrian knots up to _ legendrian isotopy _ , that is homotopy through legendrian knots .
the most basic , `` classical '' invariants of legendrian isotopy are the thurston bennequin number @xmath4 , rotation number @xmath5 , and smooth type ..
Please generate the next two sentences of the article | ( of course , any invariant of smooth isotopy is also an invariant of legendrian isotopy . ) in this paper , we will study the so - called ruling invariants , introduced by chekanov and pushkar @xcite and independently fuchs @xcite .
the beginning of legendrian knot theory dates back to 1984 when bennequin @xcite proved the famous inequality @xmath6 where @xmath7 is an arbitrary legendrian knot and @xmath8 is its ( smooth ) seifert genus . |
8,822 | Suppose that you have an abstract for a scientific paper: using idealized 1-d eulerian hydrodynamic simulations , we contrast the behavior of isolated supernovae with the superbubbles driven by multiple , collocated supernovae . continuous energy injection via successive supernovae going off within the hot / dilute bubble maintains a strong termination shock .
this strong shock keeps the superbubble over - pressured and drives the outer shock well after it becomes radiative .
isolated supernovae , in contrast , with no further energy injection , become radiative quite early ( @xmath0 myr , 10s of pc ) , and stall at scales @xmath1 pc .
we show that isolated supernovae lose almost all of their mechanical energy by a myr , but superbubbles can retain up to @xmath2 of the input energy in form of mechanical energy over the lifetime of the star cluster ( few 10s of myr ) .
these conclusions hold even in the presence of realistic magnetic fields and thermal conduction .
we also compare various recipes for implementing supernova feedback in numerical simulations . for various feedback prescriptions
we derive the spatial scale below which the energy needs to be deposited for it to couple to the interstellar medium ( ism ) .
we show that a steady thermal wind within the superbubble appears only for a large number ( @xmath3 ) of supernovae . for smaller clusters
we expect multiple internal shocks instead of a smooth , dense thermalized wind .
[ firstpage ] galaxies : ism ism : bubbles shock waves
supernova remnants .
And you have already written the first three sentences of the full article: gravity and dark energy govern the structure in the universe at the largest scales but complex baryonic processes like cooling , heating , self - gravity and star formation are important at galactic scales ( e.g. , @xcite ) .
numerical simulations have made tremendous progress in understanding galaxy formation , starting from pure gravitational n - body simulations to the current models which try to model the aforementioned complex processes .
modeling the gravitationally - interacting dark matter is straightforward in principle , and only limited by the available computing power . but.
Please generate the next two sentences of the article | the modeling of baryonic processes is rather involved .
in particular , there is no consensus on which baryonic processes are important and how they should be implemented numerically . |
8,823 | Suppose that you have an abstract for a scientific paper: we give an update on the status of the hadronic light - by - light scattering contribution to the muon @xmath0 .
we review recent work by various groups , list some of the open problems and give an outlook on how to better control the uncertainty of this contribution .
this is necessary in order to fully profit from planned future muon @xmath0 experiments to test the standard model .
despite some recent developments , we think that the estimate @xmath1 still gives a fair description of the current situation .
december 17 , 2013 + andreas nyffeler + _ regional centre for accelerator - based particle physics , harish - chandra research institute , chhatnag road , jhusi , allahabad - 211 019 , india _ + _ albert einstein center for fundamental physics , institute for theoretical physics , university of bern , sidlerstrasse 5 , ch-3012 bern , switzerland _
pacs numbers : 14.60.ef , 13.40.em , 12.38.lg .
And you have already written the first three sentences of the full article: the anomalous magnetic moment of the muon has served over many years as an important test of the standard model , see the reviews @xcite .
it is also sensitive to potential contributions from new physics .
the current status of the muon @xmath0 is summarized in table [ tab : status_g-2 ] where we list the different contributions in theory ( qed , weak , hadronic ) from various recent sources and compare with the experimental value ..
Please generate the next two sentences of the article | more references to earlier work can be found in the quoted papers and in refs .
the experimental world average is dominated by the final result of the brookhaven muon @xmath0 experiment @xcite , corrected for a small shift in the ratio of the magnetic moments of the muon and the proton @xcite . |
8,824 | Suppose that you have an abstract for a scientific paper: in this paper we introduce a cayley - type graph for group - subgroup pairs and present some elementary properties of such graphs , including connectedness , their degree and partition structure , and vertex - transitivity .
we relate these properties to those of the underlying group - subgroup pair . from the properties of the group , subgroup and generating set some of the eigenvalues can be determined , including the largest eigenvalue of the graph .
in particular , when this construction results in a bipartite regular graph we show a sufficient condition on the size of the generating sets that results on ramanujan graphs for a fixed group - subgroup pair
. examples of ramanujan pair - graphs that do not satisfy this condition are also provided , to show that the condition is not necessary . .
And you have already written the first three sentences of the full article: a ramanujan graph is a @xmath0-regular finite graph with nontrivial eigenvalues @xmath1 satisfying @xmath2 this condition is equivalent to the `` graph theoretical riemann hypothesis '' for the ihara zeta function associated to the graph , see @xcite for more information .
the above equivalence was first formulated by sunada in @xcite .
infinite families of @xmath0-regular ramanujan graphs of increasing size are examples of the more general families of expander graphs ..
Please generate the next two sentences of the article | in fact , the families of ramanujan graphs are the expander families that are optimal from the spectral point of view , according to the bounds by alon and boppana . furthermore , the known constructions of families of ramanujan graphs are essentially number theoretical ; for instance , the proof of the ramanujan property ( [ eqn : ramprop ] ) for the original families is related to the ramanujan conjecture for modular forms of weight 2 .
the families of expanders have applications to engineering and computer science , among others areas @xcite . |
8,825 | Suppose that you have an abstract for a scientific paper: we present the mid - rapidity @xmath0 yield measured in @xmath1 = 200 gev cu+cu collisions at rhic via direct reconstruction through the @xmath2 decay channel .
a charm cross - section is reported and compared to theoretical predictions and to previous rhic experimental results .
open charm , cu+cu , quark - gluon plasma , fonll , star 12.38.mh , 21.65.qr .
And you have already written the first three sentences of the full article: charm is predicted to be produced primarily in gluon fusion reactions in the early stages of a collision @xcite .
if charm is indeed produced in initial hard ( high @xmath3 ) processes , one will observe that charm production scales with the number of binary ( nucleon - nucleon ) collisions .
the charm production cross - section can be calculated by summing up feynman diagrams at the `` fixed - order plus next - to - leading - log ( fonll ) '' level ..
Please generate the next two sentences of the article | the total charm cross - section per binary collision as predicted by fonll for @xmath1 = 200 gev is @xmath4 @xcite .
both the star and phenix experiments at rhic observe binary scaling when comparing p+p to au+au ( phenix ) and d+au to au+au ( star ) ; however , previously measured charm cross - sections in star and phenix differ above declared uncertainties @xcite . |
8,826 | Suppose that you have an abstract for a scientific paper: the supernova remnant ( snr ) , ho 12 , in the center of the dwarf irregular galaxy ngc 6822 was previously observed at x - ray , optical , and radio wavelengths . by using archival _
chandra _ and ground - based optical data , we found that the snr is spatially resolved in x - rays and optical .
in addition , we obtained a @xmath0 resolution radio image of the snr .
these observations provide the highest spatial resolution imaging of an x - ray / optical / radio snr in that galaxy to date .
the multi - wavelength morphology , x - ray spectrum and variability , and narrow - band optical imagings are consistent with a snr .
the snr is a shell - shaped object with a diameter of about @xmath1 ( 24 pc ) .
the morphology of the snr is consistent across the wavelengths while the _ chandra _ spectrum can be well fitted with a nonequilibrium ionization model with an electron temperature of 2.8 kev and a 0.37 kev luminosity of @xmath2 .
the age of the snr is estimated to be @xmath3 years .
# 1to 0pt#1 [ firstpage ] .
And you have already written the first three sentences of the full article: until recently , only supernova remnants ( snrs ) in our galaxy and the magellanic clouds were resolved at x - ray wavelength . however , studies of galactic snrs can be limited by the lack of reliable distance estimates , high interstellar absorption at optical and x - ray wavelengths , and the high level of confusion in many galactic fields ( magnier et al .
these limitations are overcome by studies of snrs in nearby extragalactic systems such as the large and small magellanic clouds ( see , e.g. , hughes 2001 ) .
more recently , kong et al . ( 2002 , 2003 ) and williams et al . (.
Please generate the next two sentences of the article | 2004 ) discovered five x - ray resolved snrs in the nearest ( 780 kpc ) spiral galaxy , m31 .
more importantly , these snrs were also seen at optical and radio wavelengths . |
8,827 | Suppose that you have an abstract for a scientific paper: we present experimental results on thermoelectric power ( _ s _ ) and electrical resistivity ( @xmath0 ) of pseudobinary alloys ho(al@xmath1co@xmath2)@xmath3 ( @xmath4 ) , in the temperature range 4.2 k to 300 k. the work focuses on the effects of static ( induced by alloying ) and dynamic ( induced by temperature ) disorder on the magnetic state and electronic transport in a metallic system with itinerant metamagnetic instability .
spatial fluctuations of the local magnetic susceptibility in the alloys lead to the development of a partially ordered magnetic ground state of the itinerant 3_d _ electron system .
this results in a strong increase of the residual resistivity and a suppression of the temperature - dependent resistivity .
thermopower exhibits a complex temperature variation in both the magnetically ordered and in the paramagnetic state .
this complex temperature variation is attributed to the electronic density of states features in vicinity of fermi energy and to the interplay of magnetic and impurity scattering .
our results indicate that the magnetic enhancement of the co 3_d _ band in _ r_co@xmath5based alloys upon a substitution of co by non - magnetic elements is mainly related to a progressive localization of the co
3_d _ electrons caused by disorder .
we show that the magnitude of the resistivity jump at the curie temperature for _ r_co@xmath5 compounds exhibiting a first order phase transition is a non - monotonic function of the curie temperature due to a saturation of the 3_d_band spin fluctuation magnitude at high temperatures .
hoco@xmath5 belongs to the family of intermetallic _
r_co@xmath6 cubic laves phases ( _ r _ stands for rare earth elements ) which are well known for their outstanding magnetic properties associated with itinerant 3_d _ electron subsystem @xcite .
long - range magnetic order of the 3_d _ electron subsystem of paramagnetic yco@xmath5 and luco@xmath3 can be induced by external magnetic field exceeding a certain critical value @xmath7 .....
And you have already written the first three sentences of the full article: the samples of ho(co@xmath13al@xmath14)@xmath5 alloys were prepared from pure components by melting in an induction furnace under a protective ar atmosphere and were subsequently annealed in vacuum at 1100 k for about one week .
the x - ray analysis showed no traces of impurity phases .
a four probe dc method was used for the electrical resistivity measurements ; for the thermopower measurements a differential method was applied ..
Please generate the next two sentences of the article | typical size of the samples was about 1@xmath15 1@xmath15 10 mm@xmath16 .
the estimated error in the absolute value of the electrical resistivity is @xmath1710% . |
8,828 | Suppose that you have an abstract for a scientific paper: red - sequence galaxies record the history of terminated star - formation in the universe and can thus provide important clues to the mechanisms responsible for this termination .
we construct composite samples of published cluster and field galaxy photometry in order to study the build - up of galaxies on the red - sequence , as parameterised by the dwarf - to - giant ratio ( dgr ) .
we find that the dgr in clusters is higher than that of the field at all redshifts , implying that the faint end of the red - sequence was established first in clusters .
we find that the dgr evolves with redshift for both samples , consistent with the `` down - sizing '' picture of star formation .
we examine the predictions of semi - analytic models for the dgr and find that neither the magnitude of its environmental dependence nor its evolution is correctly predicted in the models .
red - sequence dgrs are consistently too high in the models , the most likely explanation being that the strangulation mechanism used to remove hot gas from satellite galaxies is too efficient . finally we present a simple toy model including a threshold mass , below which galaxies are not strangled , and show that this can predict the observed evolution of the field dgr .
[ firstpage ] galaxies : clusters : general galaxies : evolution galaxies : general .
And you have already written the first three sentences of the full article: red - sequence galaxies are an important population for understanding galaxy formation and evolution in general .
they represent systems with very little or no on - going star - formation and thus are a unique tracer of the past activity of galaxies .
@xcite found a deficit of faint red - sequence galaxies in clusters at [email protected] relative to local clusters ..
Please generate the next two sentences of the article | this would suggest that star formation ended earlier for the most luminous / massive galaxies at high redshift and would support the `` down - sizing '' picture first proposed by @xcite , in which the termination of star - formation progresses from the most massive to the least massive galaxies as the universe ages . similar results for clusters spanning a range of redshifts have been found by @xcite , @xcite , @xcite , @xcite and others .
similarly , surveys of field galaxies have attempted to characterise the evolution of the red - sequence luminosity function . |
8,829 | Suppose that you have an abstract for a scientific paper: the widely existing shallow decay phase of the x - ray afterglows of gamma - ray bursts ( grbs ) is generally accepted to be due to long - lasting energy injection .
the outflows carrying the injecting energy , based on the component that is dominative in energy , fall into two possible types : baryon - dominated and lepton - dominated ones .
the former type of outflow could be ejecta that is ejected during the prompt phase of a grb and consists of a series of baryonic shells with a distribution of lorentz factors , and the latter type could be an electron - positron - pair wind that is driven by the post - burst central engine .
we here provide a unified description for the dynamics of fireballs based on these two types of energy injection , and calculate the corresponding high - energy photon emission by considering synchrotron radiation and inverse compton scattering ( including synchrotron self - compton and combined inverse - compton ) of electrons .
we find that , in the two energy - injection models , there is a plateau ( even a hump ) in high - energy light curves during the x - ray shallow decay phase .
in particular , a considerable fraction of the injecting energy in the lepton - dominated model can be shared by the long - lasting reverse shock since it is relativistic .
furthermore , almost all of the energy of the reverse shock is carried by leptons , and thus the inverse - compton emission is enhanced dramatically .
therefore , this model predicts more significant high - energy afterglow emission than the baryon - dominated model .
we argue that these observational signatures would be used to discriminate between different energy - injection models in the upcoming _ gamma - ray large area space telescope _ ( glast ) era . .
And you have already written the first three sentences of the full article: as discovered by swift , there is a shallow decay phase ( temporal indices @xmath0 $ ] ) from post - burst several tens of seconds to several hours ( even days ) occurring in the x - ray afterglow light curves of a significant fraction of gamma - ray bursts ( grbs ) ( nousek et al .
2006 ; obrien et al . 2006 ; willingale et al . 2007 ; liang et al . 2007 ) .
this shallow decay phase is obviously beyond understanding of the standard afterglow model ( mszros & rees 1997 ; sari et al ..
Please generate the next two sentences of the article | 1998 ) , but is generally accepted to be due to continuous energy injection into relativistic blast waves ( e.g. , zhang et al .
2006 ; nousek et al . |
8,830 | Suppose that you have an abstract for a scientific paper: a normal ( respectively , graded normal ) vector configuration @xmath0 defines the toric ideal @xmath1 of a normal ( respectively , projectively normal ) toric variety .
these ideals are cohen - macaulay , and when @xmath2 is normal and graded , @xmath1 is generated in degree at most the dimension of @xmath3 . based on this , sturmfels asked if these properties extend to initial ideals when @xmath2 is normal , is there an initial ideal of @xmath1 that is cohen - macaulay , and when @xmath2 is normal and graded , does @xmath1 have a grbner basis generated in degree at most @xmath4 ?
in this paper , we answer both questions positively for @xmath5-normal configurations .
these are normal configurations that admit a regular triangulation @xmath5 with the property that the subconfiguration in each cell of the triangulation is again normal .
such configurations properly contain among them all vector configurations that admit a regular unimodular triangulation .
we construct non - trivial families of both @xmath5-normal and non-@xmath5-normal configurations . .
And you have already written the first three sentences of the full article: a finite vector configuration @xmath6 defines the _ toric ideal _ @xmath7 in the polynomial ring @xmath8 = { \mathbb k } [ { \bf x}]$ ] where @xmath9 is a field .
let @xmath10 and @xmath11 denote the cone , lattice and semigroup spanned by the @xmath12 and @xmath13-linear combinations of @xmath0 where @xmath13 is the set of non - negative integers .
let @xmath14 be the krull dimension of @xmath15 which equals the rank of @xmath16 ..
Please generate the next two sentences of the article | assume @xmath17 .
the configuration @xmath0 is _ normal _ if @xmath18 and _ graded _ if @xmath0 spans an affine hyperplane in @xmath19 . a finite set @xmath20 such that @xmath21 is called a _ hilbert basis _ of the semigroup @xmath22 . |
8,831 | Suppose that you have an abstract for a scientific paper: internet of things ( iot ) has emerged as a new paradigm for the future internet . in iot , enormous devices are connected to the internet and thereby being a huge data source for numerous applications . in this article , we focus on addressing data management in iot through using a smart data pricing ( sdp ) approach . with sdp ,
data can be managed flexibly and efficiently through intelligent and adaptive incentive mechanisms .
moreover , it is a major source of revenue for providers and partners .
we propose a new pricing scheme for iot service providers to determine the sensing data buying price and iot service subscription fee offered to sensor owners and service users , respectively .
additionally , we adopt the bundling strategy that allows multiple providers to form a coalition and bid their services as a bundle , attracting more users and achieving higher revenue .
finally , we outline some important open research issues for sdp and iot .
iot , bundling strategy , smart data pricing , pricing mechanism , incentive . .
And you have already written the first three sentences of the full article: internet of things ( iot ) is a novel concept that allows a number of devices to be connected through the internet .
such devices can be sensors / actuators which are able to operate and transmit data without or with minimal human intervention .
iot has brought a great influence to many areas , and there have been many iot applications implemented such as healthcare , transportation , logistics , and manufacturing @xcite ..
Please generate the next two sentences of the article | however , the development of iot is facing many challenges especially for data management @xcite . due to the special characteristics of iot systems and services ,
e.g. , heterogeneous large - scale architecture , diverse and enormous data , traditional data management approaches may become intractable such that new solutions are required . |
8,832 | Suppose that you have an abstract for a scientific paper: the ground state of spin-1 haldane chains is characterized by the so - called string order .
we show that the same hidden order is also present in ordinary one - dimensional band insulators .
we construct a family of hamiltonians which connects adiabatically band insulators to two topologically non - equivalent spin models , the haldane chain and the antiferromagnetic spin-1/2 ladder .
we observe that the localized spin-1/2 edge - state characteristic of spin-1 chains is smoothly connected to a surface - bound state of band insulators and its emergence is not related to any bulk phase transition .
furthermore , we show that the string order is absent in any dimensions higher than one .
the antiferromagnetic spin-1 chain is a prominent example of a spin - liquid , an exotic state of matter where interactions play a dual role : on the one hand a strong hund s rule coupling locally leads to the formation of magnetic spin-1 degrees of freedom , on the other hand spin correlations screen magnetism completely . as conjectured by haldane in the early eighties
@xcite , spin-1 chains are characterized by a finite gap in their spectrum and by exponentially decaying spin - spin correlations . since this seminal work a lot of progress have been made , theoretically and experimentally , towards a full description of the so - called haldane phase . in particular , affleck ,
kennedy , lieb and tasaki @xcite provided a microscopic understanding of this correlated ground state , devicing an exactly solvable model ( aklt ) adiabatically connected to the spin-1 chain .
the aklt ground state is made up solely of nearest - neighbor singlets ( or valence bonds ) and the gap in the system ( and therefore in the spin-1 chain ) corresponds to the energy needed to break a bond . in this paper
we want to address the question to what extent the haldane chain is different from an ordinary band insulator .
the latter has also a gap and an even number of electrons per unit cell and , recently , one of the....
And you have already written the first three sentences of the full article: in close analogy with the case of the spins ( eqns .
( [ soodd ] ) and ( [ soeven ] ) in the text ) , we can construct string order parameters also in the charge sector .
we define @xmath91 and @xmath92 as @xmath93 where @xmath94 . as shown in fig ..
Please generate the next two sentences of the article | [ chargestring ] , both @xmath92 and @xmath91 are finite for a generic band insulator and - up to a trivial factor @xmath95 - very similar ( but not identical ) to the spin string order parameters of fig .
[ stringorder ] . in the purely diagonal ( @xmath96 ) and vertical ( @xmath97 ) limits only one of the two string orders is different from 0 . |
8,833 | Suppose that you have an abstract for a scientific paper: hst f555w and f814w photometry of a portion of the wlm galaxy are presented .
the distance modulus is determined via fitting of the entire color - magnitude diagram to be @xmath0 , which is consistent with the rgb tip distance .
the galaxy s measurable star formation history appears to have begun no more than 12 gyr ago , with about half of wlm s total star formation ( by mass ) formed before 9 gyr ago .
the star formation rate gradually decreased , until a recent increase in activity starting between 1 and 2.5 gyr ago .
this is still continuing to the present time , and is concentrated in the bar of the galaxy , as shown by the difference in recent star formation rates in the three wf chips . .
And you have already written the first three sentences of the full article: the wlm galaxy ( ddo 221 ) is a local group dwarf irregular ( class irr iv - v ) , in an isolated part of the local group approximately 900 kpc from the milky way .
it was discovered by wolf ( 1909 ) and rediscovered by lundmark and melotte ( melotte 1926 ) , thus earning its name of wolf - lundmark - melotte , abbreviated wlm .
its distance is approximately 900 kpc , making it close enough to allow ground - based studies of its red giant branch ( rgb ) tip ( @xmath1 ) and upper main sequence , but distant enough that such studies will not reach the horizontal branch ( @xmath2 ) ..
Please generate the next two sentences of the article | ables & ables ( 1977 ) used electrographic techniques to make photometric measurements of supergiants in wlm , getting @xmath3 and @xmath4 photometry for 50 stars , the faintest having a magnitude @xmath3 of 21.6 . with this photometry , they were able to estimate a distance modulus of @xmath5 .
they also noted a `` slightly diffuse starlike object about 2 west of the center '' of the galaxy , which they determined was most likely a globular cluster with @xmath6 and @xmath7 . |
8,834 | Suppose that you have an abstract for a scientific paper: time - odd mean fields ( nuclear magnetism ) are analyzed in the framework of covariant density functional theory ( cdft ) by performing the blocking of the single - particle states with fixed signature .
it is shown that they always provide additional binding to the binding energies of odd - mass nuclei .
this additional binding only weakly depends on the rmf parametrization reflecting good localization of the properties of time - odd mean fields in cdft .
the underlying microscopic mechanism is discussed in detail .
time - odd mean fields affect odd - even mass differences .
however , our analysis suggests that the modifications of the strength of pairing correlations required to compensate for their effects are modest .
in contrast , time - odd mean fields have a profound effect on the properties of odd - proton nuclei in the vicinity of the proton - drip line . their presence can modify the half - lives of proton - emitters ( by many orders of magnitude in light nuclei ) and considerably affect the possibilities of their experimental observation . .
And you have already written the first three sentences of the full article: the development of self - consistent many - body theories aiming at the description of low - energy nuclear phenomena provides the necessary theoretical tools for an exploration of the nuclear chart into known and unknown regions .
theoretical methods ( both relativistic and non - relativistic ) formulated within the framework of density functional theory ( dft ) and effective field theory ( eft ) are the most promising tools for the global investigation of the properties of atomic nuclei .
the dft and eft concepts in nuclear structure models have been extensively discussed in a number of recent articles @xcite ..
Please generate the next two sentences of the article | the power of the models based on these concepts is essentially unchallenged in medium and heavy mass nuclei where ab - initio type few - body calculations are computationally impossible and the applicability of the spherical shell model is restricted to a few regions in the vicinity of doubly shell closures .
the self - consistent mean - field approach to nuclear structure represents an approximate implementation of kohn - sham density functional theory ( dft ) @xcite , which is successfully employed in the treatment of the quantum many - body problem in atomic , molecular and condensed matter physics . |
8,835 | Suppose that you have an abstract for a scientific paper: a full account is given of the procedure used by the authors to construct an @xmath0 supersymmetric grand unified model of the fermion mass matrices .
various features of the model which gives remarkably accurate results for the quark and lepton masses and mixings were presented earlier in separate publications . the construction of the matrices is first discussed in the framework of effective operators , from which one naturally obtains the maximal @xmath1 mixing , while the small angle or maximal mixing solutions for the solar neutrinos depend upon the nature of the majorana matrix . a set of higgs and fermion superfields is then introduced from which the higgs and yukawa superpotentials uniquely give the structure of the mass matrices previously obtained .
the right - handed majorana matrix arises from one higgs field coupling to several pairs of superheavy conjugate neutrino singlets . for the simple version considered
, 10 input parameters accurately yield the 20 masses and mixings of the quarks and leptons , and the 3 masses of the right - handed neutrinos . .
And you have already written the first three sentences of the full article: in several recent papers [ 1 - 4 ] we have developed a highly predictive model of quark and lepton masses based on the grand unified group @xmath0 .
this model grew out of our attempt @xcite to construct a realistic grand unified theory ( gut ) in which @xmath0 was broken down to the standard model in the simplest possible , or minimal " way @xcite . in this model there emerged a new mechanism based on certain well - known features of @xmath2 for explaining the large mixing between the mu and tau neutrinos that is seen at superkamiokande@xcite .
in @xcite we gave the structure of the quark and lepton mass matrices for the second and third families , treating the first family as massless ..
Please generate the next two sentences of the article | in @xcite , it was shown how to extend the model to include the first family , which leads to several interesting predictions . in @xcite , it was observed that the mixing of the electron neutrino very naturally falls either within the range @xmath3 , corresponding to the small angle msw solution @xcite of the solar neutrino problem , or very near to the value @xmath4 , corresponding to what is called bimaximal mixing " .
in this paper we present the model in fuller detail , especially in regard to neutrino phenomenology , and to the structure of the higgs sector , yukawa interactions , and flavor symmetries that underlie the quark and lepton mass matrices . |
8,836 | Suppose that you have an abstract for a scientific paper: we study the two dimensional xy model with quenched random phases and its coulomb gas formulation . a novel renormalization group ( rg ) method is developed which allows to study perturbatively the glassy low temperature xy phase and the transition at which frozen topological defects ( vortices ) proliferate .
this rg approach is constructed both from the replicated coulomb gas and , equivalently without the use of replicas , using the probability distribution of the local disorder ( random defect core energy ) . by taking into account the fusion of environments ( i.e charge fusion in the replicated coulomb gas )
this distribution is shown to obey a kolmogorov s type ( kpp ) non linear rg equation which admits travelling wave solutions and exhibits a freezing phenomenon analogous to glassy freezing in derrida s random energy models .
the resulting physical picture is that the distribution of local disorder becomes broad below a freezing temperature and that the transition is controlled by rare favorable regions for the defects , the density of which can be used as the new perturbative parameter .
the determination of marginal directions at the disorder induced transition is shown to be related to the well studied front velocity selection problem in the kpp equation and the universality of the novel critical behaviour obtained here to the known universality of the corrections to the front velocity .
applications to other two dimensional problems are mentionned at the end . .
And you have already written the first three sentences of the full article: topological phase transitions in two dimensions , which are induced by the proliferation of topological defects , are naturally described via coulomb gas formulations . in the description of the kosterlitz - thouless transition of the xy model ,
the corresponding coulomb gas ( cg ) with integer charges is obtained as an effective theory for the topological defects of the model : the vortices @xcite .
similarly , a collection of dislocations whose proliferation induce the melting transition in a two dimensional elastic lattice can be described by a coulomb gas with vector charges which belong to the reciprocal lattice@xcite ..
Please generate the next two sentences of the article | finally , most of two dimensional statistical models , such as the ising , potts and askin - teller models , can be transformed into coulomb gases @xcite ( see also the review @xcite ) . in all these cases , the transitions can be studied by renormalization in considering the screened interaction between two test coulomb charges . this interaction is logarithmic at large distance @xmath0 , and the renormalization procedure consists in neglecting the higher terms in an expansion in @xmath1 as being irrelevant @xcite .
this renormalization is thus valid for a dilute gas of charges , and is usually implemented by an expansion of the coulomb gas partition function in powers of the _ charge fugacity _ @xmath2 . |
8,837 | Suppose that you have an abstract for a scientific paper: alpha elastic scattering angular distributions of the @xmath0cd(@xmath1)@xmath0cd reaction were measured at three energies around the coulomb barrier to provide a sensitive test for the @xmath2 + nucleus optical potential parameter sets .
furthermore , the new high precision angular distributions , together with the data available from the literature were used to study the energy dependence of the locally optimized @xmath2 + nucleus optical potential in a wide energy region ranging from e@xmath3 = 27.0 mev down to 16.1 mev .
the potentials under study are a basic prerequisite for the prediction of @xmath2-induced reaction cross sections and thus , for the calculation of stellar reaction rates used for the astrophysical @xmath4 process .
therefore , statistical model predictions using as input the optical potentials discussed in the present work are compared to the available @xmath0cd + alpha cross section data .
astrophysical @xmath4 process ; elastic alpha scattering experiments , @xmath2 + nucleus optical potential .
And you have already written the first three sentences of the full article: the bulk of the naturally occurring nuclei heavier than iron observed in the solar system were synthesized via neutron capture processes . in the case of the so - called astrophysical
_ s _ process , the neutron flux is moderate , elements are synthesized through slow neutron captures and @xmath5 decays up to @xmath6bi @xcite . on the contrary , in an astrophysical environment where the neutron densities are orders of magnitude higher than the ones available for the _ s _ process , the neutron captures become faster than the @xmath5-decays and extremely neutron - rich nuclides close to the neutron drip line can be synthesized .
these nuclei decay back into the valley of stability when the neutron flux ceases . this process the so - called astrophysical.
Please generate the next two sentences of the article | _ r _ process
can only take place in explosive environments @xcite . |
8,838 | Suppose that you have an abstract for a scientific paper: the stm tunneling through a quantum wire ( qw ) with a side - attached impurity ( atom , island ) is investigated using a tight - binding model and the nonequilibrium keldysh green function method .
the impurity can be coupled to one or more qw atoms .
the presence of the impurity strongly modifies the local density of states of the wire atoms , thus influences the stm tunneling through all the wire atoms .
the transport properties of the impurity itself are also investigated mainly as a function of the wire length and the way it is coupled to the wire .
it is shown that the properties of the impurity itself and the way it is coupled to the wire strongly influence the stm tunneling which is reflected in the density of states and differential conductance . quantum wire , tunneling , stm 68.27.ef , 81.07.vb , 73.40.gk .
And you have already written the first three sentences of the full article: the invention of scanning tunneling microscopy ( stm ) @xcite was a milestone in experimental surface physics .
moreover , it became possible to tailor and analyze small nanostructures on various conducting surfaces @xcite .
perhaps the most spectacular and pioneering examples are the quantum corral experiments , in which closed atomic structures were assembled with help of atomic manipulations @xcite ..
Please generate the next two sentences of the article | as the stm is a real space technique , and is very sensitive to the local atomic and electronic structures , it allows to study the properties of various , not necessarily periodic , structures with atomic resolution .
those include various surface reconstructions @xcite and low dimensional structures , like single adatoms @xcite , islands @xcite or one - dimensional monoatomic chains @xcite-@xcite . |
8,839 | Suppose that you have an abstract for a scientific paper: the performance of wireless communication is fundamentally constrained by the limited battery life of wireless devices , whose operations are frequently disrupted due to the need of manual battery replacement / recharging .
the recent advance in radio frequency ( rf ) enabled wireless energy transfer ( wet ) technology provides an attractive solution named wireless powered communication ( wpc ) , where the wireless devices are powered by dedicated wireless power transmitters to provide continuous and stable microwave energy over the air . as a key enabling technology for truly perpetual communications , wpc opens up the potential to build a network with larger throughput , higher robustness , and increased flexibility compared to its battery - powered counterpart .
however , the combination of wireless energy and information transmissions also raises many new research problems and implementation issues to be addressed . in this article
, we provide an overview of state - of - the - art rf - enabled wet technologies and their applications to wireless communications , with highlights on the key design challenges , solutions , and opportunities ahead . .
And you have already written the first three sentences of the full article: limited device battery life has always been a key consideration in the design of modern mobile wireless technologies .
frequent battery replacement / recharging is often costly due to the large number of wireless devices in use , and even infeasible in many critical applications , e.g. , sensors embedded in structures and implanted medical devices .
rf - enabled wireless energy transfer ( wet ) technology provides an attractive solution by powering wireless devices with continuous and stable energy over the air . by leveraging the far - field radiative properties of electromagnetic ( em ) wave , wireless receivers could harvest energy remotely from the rf signals radiated by the energy transmitter ..
Please generate the next two sentences of the article | rf - enabled wet enjoys many practical advantages , such as long operating range , low production cost , small receiver form factor , and efficient energy multicasting thanks to the broadcast nature of em wave .
one important application of rf - enabled wet is _ wireless powered communication _ ( wpc ) , where the wireless devices use the harvested rf energy to transmit / decode information to / from other devices . without being interrupted from energy depletion due to communication usage |
8,840 | Suppose that you have an abstract for a scientific paper: we investigate numerically the signatures of collective modes in the tunneling spectra of superconductors
. the larger strength of the signatures observed in the high-@xmath0 superconductors , as compared to classical low-@xmath0 materials , is explained by the low dimensionality of these layered compounds .
we also show that the strong - coupling structures are dips ( zeros in the @xmath1 spectrum ) in @xmath2-wave superconductors , rather than the steps ( peaks in @xmath1 ) observed in classical @xmath3-wave superconductors .
finally we question the usefulness of effective density of states models for the analysis of tunneling data in @xmath2-wave superconductors . .
And you have already written the first three sentences of the full article: many experiments have shown that the electrons in cuprate high-@xmath0 superconductors ( hts ) are significantly renormalized by the interaction with collective modes .
this renormalization appears in photoemission measurements as velocity changes in the quasi - particle dispersion ( the `` kinks '' ) accompanied by a drop of the quasi - particle life - time @xcite . in tunneling ,
the renormalization shows up as a depression , or `` dip '' , in the @xmath4 curve with the associated nearby accumulation of spectral weight ( the `` hump '' ) @xcite ..
Please generate the next two sentences of the article | similar signatures observed by tunneling spectroscopy in classical superconductors were successfully explained by the strong - coupling theory of superconductivity @xcite .
there are , however , two striking differences between the structures observed in the cuprates and in low-@xmath0 metals such as pb or hg . |
8,841 | Suppose that you have an abstract for a scientific paper: we present an observational study of the protostellar core b335 harboring a low - mass class 0 source .
the observations of the @xmath0@xmath1 line emission were carried out using the nobeyama 45 m telescope and nobeyama millimeter array .
our combined image of the interferometer and single - dish data depicts detailed structures of the dense envelope within the core .
we found that the core has a radial density profile of @xmath2 and a reliable difference in the power - law indices between the outer and inner regions of the core : @xmath3 for @xmath4 and @xmath5 for @xmath6 .
the dense core shows a slight overall velocity gradient of @xmath7 over the scale of @xmath8 across the outflow axis .
we believe that this velocity gradient represents a solid - body - like rotation of the core .
the dense envelope has a quite symmetrical velocity structure with a remarkable line broadening toward the core center , which is especially prominent in the position velocity diagram across the outflow axis .
the model calculations of position velocity diagrams do a good job of reproducing observational results using the collapse model of an isothermal sphere in which the core has an inner free - fall region and an outer region conserving the conditions at the formation stage of a central stellar object .
we derived a central stellar mass of @xmath9 , and suggest a small inward velocity , @xmath10 in the outer core at @xmath11 .
we concluded that our data can be well explained by gravitational collapse with a quasi - static initial condition , such as shu s model , or by the isothermal collapse of a marginally critical bonnor
ebert sphere . .
And you have already written the first three sentences of the full article: in order to understand the formation processes of low - mass stars , it is important to investigate the properties of dense ( @xmath12 ) cores in molecular clouds .
such compact ( @xmath13 ) cores supply material to newly forming stars through dynamical gravitational collapse , however , detailed physical processes are still uncertain
. one of the investigative approaches is to derive the detailed density and velocity structures from observations of ( pre-)protostellar cores which are expected to retain more information than class i / ii objects for the initial conditions of gravitational collapse @xcite ..
Please generate the next two sentences of the article | dust continuum emission imaging at millimeter and submillimeter wavelengths using single - dish radio telescopes has revealed the radial density profiles , @xmath14 , of ( pre-)protostellar cores .
recent investigations have demonstrated that the profiles of class 0/i sources can be fitted by single power - law profiles over a wide range of radii ( e.g. , * ? ? ? |
8,842 | Suppose that you have an abstract for a scientific paper: detailed high resolution observations of the innermost central parts of nearby galaxies have revealed the presence of supermassive black holes@xcite .
these black holes may interact with their host galaxies by means of feedback in the form of energy and material jets ; this feedback affects the evolution of the host and gives rise to the observed relations between the black hole and the host . here
we report observations of the ultraviolet emissions of massive early - type galaxies .
we derive an empirical relation for a critical black - hole mass ( as a function of velocity dispersion ) above which the outflows from these black holes suppress star formation in their hosts by heating and expelling all available cold gas .
supermassive black holes are negligible in mass compared to their hosts but nevertheless seem to play a critical role in the star formation history of galaxies .
department of physics , university of oxford , oxford ox1 3rh , uk center for space astrophysics , yonsei university , seoul 120 - 749 , korea laboratoire dastrophysique de marseille , 13376 marseille cedex 12 , france california institute of technology , mc 405 - 47 , pasadena , ca 91125 laboratory for astronomy and solar physics , nasa goddard space flight center , greenbelt , md 20771 department of astronomy , columbia university , mc 5246 , new york , ny 10027 department of physics and astronomy , johns hopkins university , baltimore , md 21218 observatories of the carnegie institution of washington , 813 santa barbara st . , pasadena , ca 91101 department of physics and astronomy , ucla , los angeles , ca 90095 - 1562 the near - uv ( nuv ) detector of the galaxy evolution explorer satellite _ _ galex__@xcite covers a range in wavelength between @xmath0 and @xmath1 and is extremely sensitive to young stellar populations . with it
, we can detect small mass fractions of 1 - 3% of young stars formed within the last billion years@xcite .
this high sensitivity allows us to trace ongoing....
And you have already written the first three sentences of the full article: the main strategy behind the modelling approach we follow is to first calculate the collapse and merging history of individual dark matter halos , which is governed purely by gravitational interactions , and secondly to calculate the more complex physics of the baryons inside these dark matter halos , including e.g. radiative cooling of the gas , star formation and feedback from supernovae by simplified prescriptions on top of the dark matter evolution .
each of the dark matter halos consist of three main components which are distributed among individual galaxies inside them . a stellar , cold and hot gas component , where the latter is only attributed to _
central _ galaxies , the most massive galaxies inside individual halos . in the following sections.
Please generate the next two sentences of the article | , we will describe briefly the recipes used to calculate these different components which are mainly based on recipes presented in kauffmann et al.@xcite ( hereafter , k99 ) and springel et al.@xcite ( hereafter , s01 ) , and we refer readers for more details on model implementations to their work and references therein . throughout this paper
we use the following set of cosmological parameters : @xmath24 , @xmath25 , @xmath26 , @xmath27 and @xmath28 . |
8,843 | Suppose that you have an abstract for a scientific paper: we have observed 3c 279 in a @xmath0-ray flaring state in november 2008 .
we construct quasi - simultaneous spectral energy distributions ( seds ) of the source for the flaring period of 2008 and during a quiescent period in may 2010 .
data have been compiled from observations with fermi , swift , rxte , the vlba , and various ground - based optical and radio telescopes .
the objective is to comprehend the correspondence between the flux and polarization variations observed during these two time periods by carrying out a detailed spectral analyses of 3c 279 in the internal shock scenario , and gain insights into the role of intrinsic parameters and interplay of synchrotron and inverse compton radiation processes responsible for the two states . as a first step ,
we have used a multi - slice time - dependent leptonic jet model , in the framework of the internal shock scenario , with radiation feedback to simulate the sed of 3c 279 observed in an optical high state in early 2006 . we have used physical jet parameters obtained from the vlba monitoring to guide our modeling efforts .
we briefly discuss the effects of intrinsic parameters and various radiation processes in producing the resultant sed . .
And you have already written the first three sentences of the full article: blazars are well known for their variability and power of polarized radiation across a wide range of the electromagnetic spectrum @xcite . in some cases
, the flux can vary on timescales as short as an hour or less ( see e.g. , * ? ? ?
* ; * ? ? ?.
Please generate the next two sentences of the article | blazars exhibit a doubly - peaked spectral energy distribution ( sed ) , in which the low - energy component could extend from radio through uv or x - rays while the high - energy component extends from x - rays to @xmath0-rays .
the low - frequency component of the sed is almost certainly due to synchrotron emission from nonthermal , ultra - relativistic electrons . |
8,844 | Suppose that you have an abstract for a scientific paper: using a specific model for the expansion rate of the universe as a function of scale factor , it is demonstrated that the equation of state of the dark energy can not be determined uniquely from observations at redshifts @xmath0 unless the fraction of the mass density of the universe in nonrelativistic particles , @xmath1 , somehow can be found independently . a phenomenological model is employed to discuss the utility of additional constraints from the formation of large scale structure and the positions of cmb peaks in breaking the degeneracy among models for the dark energy . epsf = msbm10 = msbm7 = msbm5 = = = # 1#1 5125 ! .
And you have already written the first three sentences of the full article: although observations of acoustic peaks in the cosmic microwave background ( cmb ) fluctuation spectra are sensitive to the curvature of spacetime , and appear to require some form of cosmological dark energy , they may be less useful for discriminating among different equations of state for the dark energy .
various studies ( e.g. ) have concluded that the signatures of different types of spatially smooth , evolving dark energy on the cmb spectra are relatively undiscriminating , in part because cmb fluctuations were formed at high redshift , when the dark energy was not a prominent constituent , although spatial fluctuations in the dark energy could lift the degeneracy considerably @xcite . by contrast
, observations of sources at small to moderate redshifts ( @xmath0 ) would probe epochs where the dark energy is prominent , leading to suggestions that observations of type ia supernovae or of galaxy counts could be used to determine the nature of the dark energy most effectively . however , the efficacy of these observational programs is controversial , as there is considerable degeneracy among the predictions of different dark energy models for , for example , the luminosity distance as a function of redshift@xcite ..
Please generate the next two sentences of the article | one approach to the analysis of low redshift data would be to presume particular classes of models , perhaps parametrized by a series expansion of @xmath2 , and then attempt to constrain the model parameters by a likelihood or bayesian method ( e.g. ) .
a second approach is to fit the data by a parametric representation of , for example , the luminosity distance as a function of redshift , and then analyze the results to constrain the properties of the dark energy indirectly ( e.g. ) . although the first approach is preferable ( because it generally avoids difficulties associated with differentiating data , and allows a simpler assessment of uncertainties in derived parameters , in addition to outlining its implicit assumptions more clearly ) , the second approach is more useful for understanding whether or not such observations can ever yield a unique solution for the dark energy equation of state . in this short note , |
8,845 | Suppose that you have an abstract for a scientific paper: we develop techniques to determine the mass scale of invisible particles pair - produced at hadron colliders .
we employ the constrained mass variable @xmath0 , which provides an event - by - event lower - bound to the mass scale given a mass difference .
we complement this variable with a new variable @xmath1 which provides an additional _ upper _ bound to the mass scale , and demonstrate its utility with a realistic case study of a supersymmetry model .
these variables together effectively quantify the ` kink ' in the function @xmath2 which has been proposed as a mass - determination technique for collider - produced dark matter .
an important advantage of the @xmath0 method is that it does not rely simply on the position at the endpoint , but it uses the additional information contained in events which lie far from the endpoint .
we found the mass by comparing the herwig generated @xmath0 distribution to ideal distributions for different masses .
we find that for the case studied , with @xmath3 of integrated luminosity ( about @xmath4 signal events ) , the invisible particle s mass can be measured to a precision of @xmath5 .
we conclude that this technique s precision and accuracy is as good as , if not better than , the best known techniques for invisible - particle mass - determination at hadron colliders . .
And you have already written the first three sentences of the full article: if dark matter is produced at a hadron collider , its likely signature will be missing transverse momentum . to help determine the underlying origin of the observed dark - matter , it is important to measure the masses of the new particle states .
mass determination is a key part to identifying the underlying theory which lies beyond the standard model .
newly discovered particles could be kaluza - klein ( kk ) states from extra - dimensions , supersymmetric partners of known states , technicolor hadrons , or something else that we have not anticipated ..
Please generate the next two sentences of the article | models predict relationships between parameters : supersymmetry relates the couplings of current fermions to the couplings of new bosons and the supersymmetric particle masses reflect the origin of supersymmetry breaking ; masses of kk states tell us about the size of the extra dimensions . in general
, mass determination of new particle states is central to discerning what lies beyond the standard model . |
8,846 | Suppose that you have an abstract for a scientific paper: x - ray data of the centaurus cluster , obtained with _ xmm - newton _ for 45 ksec , were analyzed .
deprojected epic spectra from concentric thin shell regions were reproduced equally well by a single - phase plasma emission model , or by a two - phase model developed by _
asca _ , both incorporating cool ( 1.72.0 kev ) and hot ( @xmath0 kev ) plasma temperatures .
however , epic spectra with higher statistics , accumulated over 3-dimentional thick shell regions , were reproduced better by the two - phase model than by the singe - phase one .
therefore , hot and cool plasma phases are inferred to co - exist in the cluster core region within @xmath1 kpc .
the iron and silicon abundances of the plasma were reconfirmed to increase significantly towards the center , while that of oxygen was consistent with being radially constant .
the implied non - solar abundance ratios explains away the previously reported excess x - ray absorption from the central region .
although an additional cool ( @xmath2 kev ) emission was detected within @xmath3 kpc of the center , the rgs data gave tight upper limits on any emission with a tempeartures below @xmath4 kev .
these results are compiled into a magnetosphere model , which interprets the cool phase as confined within closed magnetic loops anchored to the cd galaxy . when combined with so - called rosner - tucker - vaiana mechanism which applies to solar coronae
, this model can potentially explain basic properties of the cool phase , including its temperature and thermal stability . .
And you have already written the first three sentences of the full article: intra - cluster medium ( icm ) , i.e. , the hot plasma confined within the gravitational potential of clusters of galaxies , constitutes the most dominant _ known _ form of baryons .
the icm was thought to cool over the hubble time by emitting optically - thin thermal x - rays , because its radiative cooling time is estimated to be @xmath5 yr at the center of many `` cd clusters '' ( those hosting cd galaxies at their centers ) .
this inspired so - called cooling flow ( hereafter cf ) hypothesis ( e.g. * ? ? ?.
Please generate the next two sentences of the article | the idea was apparently supported by several soft x - ray features observed around cd galaxies , including general decreases of the icm temperature , strong excess x - ray surface brightness , and excess photoelectric absorption up to a few times @xmath6 @xmath7 . with the first imaging capability over a broad x - ray energy band up to 10 kev and a much improved energy resolution than was available before , _
@xcite has provided a number of new results that altogether cast serious doubt upon the reality of cfs . |
8,847 | Suppose that you have an abstract for a scientific paper: we present the ( array processor experiment ) project for the development of dedicated parallel computers for numerical simulations in lattice gauge theories .
while is a production machine in today s physics simulations at various sites in europe , a new machine , , is currently being developed to provide multi - tflops computing performance . like previous machines ,
the new supercomputer is largely custom designed and specifically optimized for simulations of lattice qcd .
13 = 14.5pt .
And you have already written the first three sentences of the full article: for many non - perturbative problems in quantum field theory , numerical simulations on the lattice offer the only known way to compute various quantities from first principles .
much progress has been made during recent years @xcite , e.g. in calculating the light hadron spectrum , the light quark masses , the running coupling constant @xmath0 or observables in heavy quark physics .
further - on , lattice simulations allow the study of phenomena , like chiral symmetry breaking and confinement , or of phase transitions in the early universe ..
Please generate the next two sentences of the article | the computer resources required for such simulations are huge and critically depend on the physical parameters , like quark masses , and the formulation of the theory on the lattice , e.g. with improved chiral properties . to make the necessary resources available , various research groups engage in the development of massively parallel computers which are specifically optimized for this kind of applications .
one of these projects is ape @xcite which is currently developing its fourth generation of machines , , within the framework of an european collaboration by infn ( italy ) , desy ( germany ) and the university of paris sud ( france ) . |
8,848 | Suppose that you have an abstract for a scientific paper: in this work we use the radiation hydrodynamic code tramp to perform a two - dimensional axially symmetric model of the layered disc . using this model
we follow the accumulation of mass in the dead zone due to the radially varying accretion rate .
we found a new type of instability which causes the dead zone to split into rings .
this `` ring instability '' works due to the positive feedback between the thickness of the dead zone and the mass accumulation rate .
we give an analytical description of this instability , taking into account non - zero thickness of the dead zone and deviations from the keplerian rotational velocity .
the analytical model agrees reasonably well with results of numerical simulations .
finally , we speculate about the possible role of the ring instability in protoplanetary discs and in the formation of planets .
[ firstpage ] solar system : formation , accretion discs , hydrodynamics , instabilities . .
And you have already written the first three sentences of the full article: the layered disc model was proposed by @xcite to account for accretion - related phenomena in t tauri stars .
he assumed that the angular momentum is transported by the magneto - rotational instability , commonly referred to as the mri @xcite .
however , in the outer disc ( beyond @xmath0 au ) the temperature and the ionization degree is so low that the gas is not well coupled to the magnetic field and the mri decays ..
Please generate the next two sentences of the article | there , the only parts of the disc in which the mri can operate are the surface layers that are ionized by cosmic rays ( ionization due to x - ray quanta emitted by the central star was also considered ; see @xcite ) .
sandwiched between the active surface layers is an mri - free , and , consequently , non - viscous area near the mid - plane of the disc , commonly referred to as the dead zone . |
8,849 | Suppose that you have an abstract for a scientific paper: we obtain the phase diagram in the parameter space @xmath0 and an accurate estimate of the critical line separating the different phases .
we show several measuments of the magnetization , dimerization , nearest neighbours correlation , and density of energy in the different zones of the phase diagram , as well as a measurement of the string order parameter proposed as the non vanishing phase order parameter characterizing haldane phases .
all these results will be compared in the limit @xmath1 with the behaviour of the @xmath2 bond alternated heisenberg chain ( bahc ) .
the analysis of our data supports the existence of a dimer phase separated by a critical line from a haldane one , which has exactly the same nature as the haldane phase in the @xmath2 bahc . .
And you have already written the first three sentences of the full article: quantum systems when placed in low dimensional lattices typically exhibit strongly correlated effects driving them towards regimes with no classical analog .
many properties of these regimes or quantum phases @xcite depend in turn on the properties of their ground state and low lying energy excitations @xcite .
a problem of particular interest in the field of strongly correlated systems is the emergence of critical phases in a system where the generic behaviour as coupling constants are varied is to be a gapped system , although those gapped phases may be of different nature . in this paper.
Please generate the next two sentences of the article | we address this problem by selecting a system of quantum spins that allows us to perform a detailed study of critical and non - critical phases on equal footing , i.e. , without any bias towards an a priori preferred phase . for reasons explained in sect.[sect_model ] ,
the quantum spins are arranged in a 2-leg ladder lattice @xcite with anti - ferromagnetic heisenberg couplings along the legs while rung couplings are ferromagnetic . |
8,850 | Suppose that you have an abstract for a scientific paper: we have computed a series of realistic and self - consistent models of the emitted spectra of hii galaxies .
our models combine different codes of chemical evolution , evolutionary population synthesis and photoionization .
the emitted spectrum of hii galaxies is reproduced by means of the photoionization code cloudy , using as ionizing spectrum the spectral energy distribution of the modelled hii galaxy , which in turn is calculated according to a star formation history ( sfh ) and a metallicity evolution given by a chemical evolution model that follows the abundances of 15 different elements .
the contribution of emission lines to the broad - band colours is explicitly taken into account .
the results of our code are compared with photometric and spectroscopic data of hii galaxies .
our technique reproduces observed diagnostic diagrams , abundances , equivalent width - colour and equivalent width - metallicity relations for local hii galaxies .
[ firstpage ] galaxies : abundances galaxies : evolution galaxies : starburst galaxies : stellar content .
And you have already written the first three sentences of the full article: hii galaxies , a subset of blue compact galaxies ( bcg ) , are gas rich dwarf galaxies whose optical spectra are dominated by strong and narrow emission lines .
they are currently experiencing intense star formation in small volumes .
the emission lines are produced by gas ionized by the young massive stars ..
Please generate the next two sentences of the article | observations indicate that hii galaxies are in general metal poor systems .
this fact in addition to their very young stellar populations has been known for some time and has led to the proposal that these systems are very young , suffering their first burst of star formation @xcite . |
8,851 | Suppose that you have an abstract for a scientific paper: i review the main characteristics of structure formation in the quintessential universe . assuming equation of state @xmath0const i provide a brief description of the background cosmology and discuss the linear growth of density perturbations , the strongly nonlinear evolution , the power spectra and rms fluctuations as well as mass functions focusing on the three values @xmath1 and @xmath2 .
finally i describe the presently available and future constraints on @xmath3 . .
And you have already written the first three sentences of the full article: our knowledge of background cosmology has recently improved dramatically due to new supernovae and cosmic microwave background data .
current observations favor a flat universe with matter density @xmath4 @xcite and the remaining contribution in the form of cosmological constant @xcite or some other form of dark energy .
the models with cosmological constant are known , however , to suffer from two major problems ..
Please generate the next two sentences of the article | one is related to the origin of the constant - it can not be explained in terms of the vacuum energy since its energy is orders of magnitude smaller .
the other is the lack of explanation why the present densities in matter and cosmological constant are comparable |
8,852 | Suppose that you have an abstract for a scientific paper: if alice must communicate with bob over a channel shared with the adversarial eve , then bob must be able to validate the authenticity of the message .
in particular we consider the model where alice and eve share a discrete memoryless multiple access channel with bob , thus allowing simultaneous transmissions from alice and eve . by traditional random coding arguments
, we demonstrate an inner bound on the rate at which alice may transmit , while still granting bob the ability to authenticate .
furthermore this is accomplished in spite of alice and bob lacking a pre - shared key , as well as allowing eve prior knowledge of both the codebook alice and bob share and the messages alice transmits . .
And you have already written the first three sentences of the full article: in this paper we study physical layer authentication over a noisy multiple access channel and no pre - shared key .
such scenarios may occur when a network is established in a hostile environment .
being able to trust the information observed is just as important as actually observing it ..
Please generate the next two sentences of the article | it also stands to reason , that always having a pre - shared key seems restrictive as it is dependent on a method to generate and secure the key .
we model this scenario by considering two transmitters ( alice and neer - do - well eve ) and one receiver ( bob ) . |
8,853 | Suppose that you have an abstract for a scientific paper: solar flares are sudden flashes of brightness on the sun and are often associated with coronal mass ejections and solar energetic particles which have adverse effects in the near earth environment . by definition , flares are usually referred to * bright * features resulting from excess emission . using the newly commissioned 1.6 m new solar telescope at big bear solar observatory , here we show a striking `` negative '' flare with a narrow , but unambiguous `` * * dark * * '' moving front observed in 10830 , which is as narrow as 340 km and is associated with distinct spectral characteristics in h@xmath0 and lines .
theoretically , such negative contrast in 10830 can be produced under special circumstances , by nonthermal - electron collisions , or photoionization followed by recombination .
our discovery , made possible due to unprecedented spatial resolution , confirms the presence of the required plasma conditions and provides unique information in understanding the energy release and radiative transfer in astronomical objects . .
And you have already written the first three sentences of the full article: solar flares are the result of sudden energy release , often exceeding @xmath1 ergs , from magnetic reconnection @xcite .
the main manifestation of flares is extensive emission over much of the electromagnetic spectrum .
intriguingly , under some special circumstances , negative flare contrasts ( decrease of intensity ) are occasionally reported in stellar observations in visible continuum wavelengths @xcite . in those cases , a 20% negative contrast in the optical continuum.
Please generate the next two sentences of the article | is typically detected prior to the initial brightening @xcite .
the widely accepted postulate for generating negative flares is the h@xmath2 absorption model @xcite , in which a bombarding beam of electrons penetrates to the lower and cooler atmosphere and causes enhanced collisional ionization of hydrogen , and leads to an increase of electron density and eventually an increase of h@xmath3 opacity . as a result , |
8,854 | Suppose that you have an abstract for a scientific paper: the frequency - dependent mean free paths ( mfps ) of vibrational heat carriers in amorphous silicon are predicted from the length dependence of the spectrally decomposed heat current ( sdhc ) obtained from non - equilibrium molecular dynamics simulations .
the results suggest a ( frequency)@xmath0 scaling of the room - temperature mfps below 5 thz .
the mfps exhibit a local maximum at a frequency of 8 thz and fall below 1 nm at frequencies greater than 10 thz , indicating localized vibrations .
the mfps extracted from sub-10 nm system - size simulations are used to predict the length - dependence of thermal conductivity up to system sizes of 100 nm and good agreement is found with separate molecular dynamics simulations . weighting the sdhc by the frequency - dependent quantum occupation function provides a simple and convenient method to account for quantum statistics and provides reasonable agreement with the experimentally - measured trend and magnitude . .
And you have already written the first three sentences of the full article: compared to heat transfer by phonons in crystalline materials , heat transfer in amorphous materials is complicated by the existence of three regimes of vibrational modes.@xcite low - frequency propagons are delocalized and have a well - defined wave vector and group velocity,@xcite similar to phonons in crystals , while high - frequency locons are localized and contribute negligibly to thermal conduction.@xcite diffusons have intermediate frequencies and are delocalized , but do not have well - defined wave vectors or group velocities .
the contribution of diffusons to thermal conduction can be notable , however , as they occupy the majority of the vibrational spectrum.@xcite from kinetic theory,@xcite the contribution of an individual phonon or propagon mode to thermal conductivity is proportional to its mean free path ( mfp ) . because diffusons do not have a well - defined group velocity , it is not clear if they have a mfp or how it can be defined .
their contribution to thermal conductivity can be predicted using their diffusivity , which is well - defined and can be calculated from allen - feldman theory.@xcite nevertheless , it would be insightful to identify a frequency - dependent length scale for propagons and diffusons describing the decay of the heat flux at each vibrational frequency ..
Please generate the next two sentences of the article | such a definition would lift the ( fundamentally ) arbitrary distinction between propagons and diffusons and enable a unified description of heat transfer at all vibrational frequencies . in this paper , we apply the spectrally - decomposed mfp method@xcite to probe the non - equilibrium mfps of vibrational heat carriers in amorphous silicon ( a - si ) .
this method is based on calculating the spectrally - decomposed heat current ( sdhc)@xcite in systems of different lengths using non - equilibrium molecular dynamics ( nemd ) simulations . |
8,855 | Suppose that you have an abstract for a scientific paper: we calculate the contribution of meson and pomeron exchanges to the double - spin asymmetry in @xmath0-meson electromagnetic production at hermes energies .
we show that the observed double - spin asymmetries , which are large , can be explained by the interference between the natural parity @xmath1-secondary reggeon and the unnatural parity anomalous @xmath2 exchanges .
170 mm 250 mm -5 mm -10 mm * a mechanism for the double - spin asymmetry in electromagnetic @xmath0 production at hermes * n.i .
kochelev,@xmath3 d .- p .
min,@xmath4 v. vento,@xmath5 and a.v .
vinnikov@xmath6 _ _ @xmath7 bogoliubov laboratory of theoretical physics , jinr , dubna , moscow region , 141980 russia + @xmath8 institute of physics and technology , almaty , 480082 , kazakhstan + @xmath4 school of physics and center for theoretical physics , + seoul national university , seoul 151 - 747 , korea + @xmath5 departament de fsica terica and institut de fsica corpuscular , universitat de valncia - csic e-46100 , burjassot ( valencia ) , spain .
And you have already written the first three sentences of the full article: the measurement of spin observables gives very important information on the structure of the strong interactions @xcite .
recently , the hermes collaboration has found a significant ( @xmath9 20@xmath10 ) double - spin asymmetry in elastic vector meson electroproduction at energy @xmath11 gev @xcite .
this result is quite intriguing since it was not expected within models of the vector meson production processes based on convenient mesonic and pomeron exchanges ..
Please generate the next two sentences of the article | there are two different approaches to describe the electromagnetic production of light vector mesons at intermediate energies @xcite and @xcite .
the first assumes that only @xmath12 and @xmath13 exchanges are relevant for explaining the @xmath0 and @xmath14 cross sections and their relation . |
8,856 | Suppose that you have an abstract for a scientific paper: wide range equation of state ( eos ) for liquid hydrogen is ultimately built by combining two kinds of density functional theory ( dft ) molecular dynamics simulations , namely , first - principles molecular dynamics simulations and orbital - free molecular dynamics simulations .
specially , the present introduction of short cutoff radius pseudopotentials enables the hydrogen eos to be available in the range @xmath0 to @xmath1 g/@xmath2 and up to @xmath3 k. by comprehensively comparing with various attainable experimental and theoretical data , we derive the conclusion that our dft - eos can be readily and reliably conducted to hydrodynamic simulations of the inertial confinement fusion . .
And you have already written the first three sentences of the full article: wide range equation of state ( eos ) for hydrogen or its isotopes is of crucial interest for inertial confinement fusion ( icf ) and astrophysics @xcite . in the traditional central - hot - spot ignition designs of icf
, a deuterium - tritium ( d - t ) capsule is assumed to be imploded to high density either directly by high power laser pulses @xcite or indirectly by x rays generated in the hohlraum @xcite . due to the fact that the compressibility of the capsule is determined by eos ,
high precision eos of the d - t fuel is essential for hydrodynamic simulations and ignition facility designs . in astrophysics ,.
Please generate the next two sentences of the article | the giant jovian planets , such as jupiter , saturn , uranus , and neptune , are composed primarily of hydrogen and helium .
the knowledge on the size and mass distribution of giant jovian planets are sensitive to the eos of hydrogen in a wide range @xcite . |
8,857 | Suppose that you have an abstract for a scientific paper: in this paper we explore the concept of hierarchy as a quantifiable descriptor of ordered structures , departing from the definition of three conditions to be satisfied for a hierarchical structure : _ order _ , _ predictability _ and _ pyramidal structure_. according to these principles we define a hierarchical index taking concepts from graph and information theory .
this estimator allows to quantify the hierarchical character of any system susceptible to be abstracted in a feedforward causal graph , i.e. , a directed acyclic graph defined in a single connected structure .
our hierarchical index is a balance between this predictability and pyramidal condition by the definition of two entropies : one attending the onward flow and other for the backward reversion .
we show how this index allows to identify hierarchical , anti - hierarchical and non hierarchical structures .
our formalism reveals that departing from the defined conditions for a hierarchical structure , feedforward trees and the inverted tree graphs emerge as the only causal structures of maximal hierarchical and anti - hierarchical systems , respectively .
conversely , null values of the hierarchical index are attributed to a number of different configuration networks ; from linear chains , due to their lack of pyramid structure , to full - connected feedforward graphs where the diversity of onward pathways is canceled by the uncertainty ( lack of predictability ) when going backwards .
some illustrative examples are provided for the distinction among these three types of hierarchical causal graphs .
* the idea of hierarchy has been largely attributed to a disparate number of systems and , although easily perceived , its quantification is not a trivial issue . in this work
we quantify the hierarchy of a given causal structure with a feedforward structure . starting with the representation of a system of causal relations as a graph
, we define a non heuristic measure of hierarchy having strong grounds on the principles....
And you have already written the first three sentences of the full article: the existence of some sort of hierarchical order is an apparently widespread feature of many complex systems , including gene @xcite and human brain @xcite networks , ecosystems @xcite , social and urban structures @xcite , the internet @xcite or open - source communities @xcite .
the presence of such underlying order in the multiscale organization of complex systems is a long standing hypothesis @xcite giving rise to the idea of hierarchy as a central concept -see also @xcite . although usually treated only in qualitative terms , some formal approaches to the problem have been proposed .
the efforts towards a well - defined quantification of hierarchical order have been improving by means of complex networks theory . as a key part of their organization.
Please generate the next two sentences of the article | , dedicated efforts have been made towards a proper identification of hierarchical trends .
one outcome of these efforts has been a number of powerful , heuristic measures @xcite . |
8,858 | Suppose that you have an abstract for a scientific paper: we examine the distinct part of the density autocorrelation function @xmath0 , also called the intermediate scattering function , from the point of view of the vibration - transit ( v - t ) theory of monatomic liquid dynamics .
a similar study has been reported for the self part , and we study the self and distinct parts separately because their damping processes are not simply related .
we begin with the perfect vibrational system , which provides precise definitions of the liquid correlations , and provides the vibrational approximation @xmath1 at all @xmath2 and @xmath3 .
two independent liquid correlations are defined , motional and structural , and these are decorrelated sequentially , with a crossover time @xmath4 .
this is done by two independent decorrelation processes : the first , vibrational dephasing , is naturally present in @xmath1 and operates to damp the motional correlation ; the second , transit - induced decorrelation , is invoked to _ enhance _ the damping of motional correlation , and then to damp the structural correlation .
a microscopic model is made for the transit drift , " the averaged transit motion that damps motional correlation on @xmath5 .
following the previously developed self - decorrelation theory , a microscopic model is also made for the transit random walk , " which damps the structural correlation on @xmath6 .
the complete model incorporates a property common to both self and distinct decorrelation : simple exponential decay following a delay period , where the delay is @xmath4 , the time required for the random walk to emerge from the drift .
our final result is an accurate expression for @xmath0 for all @xmath2 through the first peak in @xmath7 .
( a modification will be required at @xmath2 where @xmath7 converges to zero . )
the theory is calibrated and tested using molecular dynamics ( md ) calculations for liquid na at 395 k ; however , the theory itself does not depend on md , and we consider other means for calibrating it . .
And you have already written the first three sentences of the full article: our goal in developing v - t theory is to apply the established techniques of many body physics to the mechanical problem of the motion of atoms in a monatomic liquid .
the many body formulation begins with an approximate hamiltonian @xmath8 composed of a complete orthogonal set of excitations , bosons or fermions , whose exact statistical mechanics is known .
@xmath8 is complemented with an interaction hamiltonian @xmath9 , expressing the key effect missing from @xmath8 , and often but not always treated as a perturbation ..
Please generate the next two sentences of the article | the approach was developed to treat the wide variety of physical behaviors observed in condensed matter , and is well illustrated in the monographs of pines @xcite and kittel .
@xcite the principles are evident in boltzmann s theory for a gas of freely moving atoms which interact via collisions , @xcite and in the theory of born and coworkers for a crystal of harmonic phonons interacting via anharmonicity . |
8,859 | Suppose that you have an abstract for a scientific paper: in a recent paper ( ruffa @xcite ) it was proposed that the massive black hole at the galactic center may act as a gravitational lens focusing gravitational wave energy to the earth .
considering the gravitational wave signal emitted by galactic spinning pulsars , an enhancement in the gravitational wave intensity by a factor of a few thousand is found . for galactic and extra - galactic sources the intensity enhancement can be as high as 4,000 and 17,000 , respectively . in this note
we consider the probability of significant signal enhancement from galactic and extra - galactic pulsars by the proposed mechanism and find that it is actually negligible . the lensing effect due to a possible companion object ( a star or the galactic center black hole ) of the gravitational wave source is also investigated in the framework of the classical microlensing theory . .
And you have already written the first three sentences of the full article: gravitational lensing of electromagnetic waves is a well known phenomenon predicted by the general theory of relativity ( for a review on this issue see schneider , ehlers and falco @xcite ) . in principle
, gravitational lensing of gravitational waves should occur in the same way as it does for light .
the most obvious difference is that gravitational wave propagation is not disturbed by dust grains , as happens for light , so that the central part of our galaxy may be investigated by using the next generation of gravitational wave detectors . in a very interesting paper ruffa ( @xcite ) , assuming that the mass of the galactic center is in the form of a massive black hole with mass @xmath0 m@xmath1 ( for a galactic center overview see eckart , genzel , ott and schoedel @xcite ) , the gravitational wave lensing problem was studied by a typical fraunhoffer diffraction approach ..
Please generate the next two sentences of the article | it was pointed out ( ruffa @xcite ) that extra galactic sources can be amplified by a factor of about @xmath2 and galactic neutron stars by over @xmath3 .
the author also argued that the earth would take about 10.1 days to traverse the focused region of the extra galactic sources . for galactic bulge sources the focused region |
8,860 | Suppose that you have an abstract for a scientific paper: observations of cataclysmic variables show a number of phenomena that do not fit easily into the standard magnetic braking scenario .
these include the large spread in mass transfer rates , the low surface temperatures of many of the companion stars , and evidence for material at low velocities .
we propose that these anomalies have a common cause : the presence of a circumbinary ( cb ) disk .
this may be a significant component of mass transferring binaries in general .
direct detection of such cb disks may be possible but difficult , because of their low luminosity and spectral energy distribution peaking in the mid - ir .
# 1_#1 _ # 1_#1 _ = # 1 1.25 in .125 in .25 in .
And you have already written the first three sentences of the full article: the standard picture for the evolution of cataclysmic variables ( cv ) , now nearly 2 decades old , has been reasonably successful as a framework for interpreting the phenomenology of cv . in this interpretation ,
angular momentum loss by gravitational waves and magnetic braking causes cataclysmic binaries to evolve from longer to shorter orbital periods ( @xmath0 ) , with magnetic braking dominating above the ` period gap ' ( @xmath1 hr ) , and a lower braking rate below this gap ( @xmath2 hr ) .
this picture explains some overall statistical properties , for example the existence of the period gap itself and the higher mass transfer rate above the gap compared to short period systems ..
Please generate the next two sentences of the article | an additional element of the phenomenology , independent of the magnetic braking scenario but not in conflict with it either , is the existence of outflows from the accretion disk .
evidence for outflows comes from the profiles in uv - lines seen in outbursts of dwarf novae ( e.g. woods et al . 1992 ) , possibly the single - peaked line profiles of the novalike ( nl ) and sw sex binaries ( see however hellier 2000 for an alternative explantation of these line profiles ) , and other indications for outflow ( e.g. long et al . |
8,861 | Suppose that you have an abstract for a scientific paper: we carry out a detailed analysis of the light higgs bosons in supersymmetric left - right models ( slrm ) .
this includes models with minimal particle content and those with additional higgs superfields .
we also consider models with non - renormalizable higher - dimensional terms .
we obtain an upper bound on the mass of the lightest @xmath0-even neutral higgs boson in these models .
the upper bound depends only on the gauge couplings , and the vacuum expectation values of those neutral higgs fields which control the spontaneous breakdown of the @xmath1 gauge symmetry .
we calculate the one - loop radiative corrections to this upper bound , and evaluate it numerically in the minimal version of the supersymmetric left - right model .
we consider the couplings of this lightest @xmath0-even higgs boson to the fermions , and show that in a phenomenologically viable model the branching ratios are similar to the corresponding branching ratios in the minimal supersymmetric standard model ( mssm ) .
we then study the most promising particle for distinguishing the slrm from other models , namely the doubly charged higgs boson .
we obtain the mass of this doubly charged higgs boson in different types of supersymmetric left - right models , and discuss its phenomenology .
hip-1999 - 16/th supersymmetry ; left - right symmetry ; higgs boson ; doubly charged higgs boson .
And you have already written the first three sentences of the full article: one of the central problems of particle physics is to understand how the electroweak scale associated with the mass of the w boson is generated , and why it is so small as compared to the planck scale associated with the newton s constant . in the standard model ( sm ) the electroweak scale is generated through the vacuum expectation value ( vev ) of the neutral component of a higgs doublet @xcite .
apart from the fact that this vev is an arbitrary parameter in the sm , the mass parameter of the higgs field suffers from quadratic divergences , making the weak scale unstable under radiative corrections .
supersymmetry is at present the only known framework in which the weak scale is stable under radiative corrections @xcite , although it does not explain how such a small scale arises in the first place . as such.
Please generate the next two sentences of the article | , considerable importance attaches to the study of supersymmetric models , especially the minimal supersymmetric standard model ( mssm ) , based on the gauge group @xmath1 , with two higgs doublet superfields .
it is well known that , because of underlying gauge invariance and supersymmetry ( susy ) , the lightest higgs boson in mssm has a tree level upper bound of @xmath2 ( the mass of z boson ) on its mass @xcite . |
8,862 | Suppose that you have an abstract for a scientific paper: the radiative transfer model ( rtm ) and the retrieval algorithm , incorporated in the sciatran 2.2 software package developed at the institute of remote sensing / institute of enviromental physics of bremen university ( germany ) , allows to simulate , among other things , radiance / irradiance spectra in the 2400 - 24000 range . in this work we present applications of rtm to two case studies . in the first case
the rtm was used to simulate direct solar irradiance spectra , with different water vapor amounts , for the study of the water vapor content in the atmosphere above sierra nevada observatory .
simulated spectra were compared with those measured with a spectrometer operating in the 8000 - 10000 range . in the second case
the rtm was used to generate telluric model spectra to subtract the atmospheric contribution and correct high - resolution stellar spectra from atmospheric water vapor and oxygen lines .
the results of both studies are discussed . .
And you have already written the first three sentences of the full article: * use modern radiative transfer models of the earth s atmosphere for astronomical applications . * two uses : * * site testing for water vapor content . * * elimination of telluric lines from optical spectra without the need for contemporary telluric standards .
@xmath0the radiative transfer model ( rtm ) and the retrieval algorithm , incorporated in the sciatran 2.2 software package developed at the institute of remote sensing / institute of enviromental physics of bremen university ( germany ) , allows to simulate , among other things , radiance / irradiance spectra in the 2400 - 24000 range . in this work
we present the applications of rtm to two case studies . in the first case.
Please generate the next two sentences of the article | the rtm was used to simulate direct solar irradiance spectra , with different water vapor amounts , for the study of the water vapor content in the sierra nevada observatory ( osn ) atmosphere .
simulated spectra were compared with those measured with a spectrometer operating in the 8000 - 10000 range . in the second case the rtm |
8,863 | Suppose that you have an abstract for a scientific paper: in this article , we study the @xmath0 and @xmath1 triply heavy baryon states in a systematic way by subtracting the contributions from the corresponding @xmath2 and @xmath3 triply heavy baryon states with the qcd sum rules , and make reasonable predictions for their masses .
+ zhi - gang wang + department of physics , north china electric power university , baoding 071003 , p. r. china pacs number : 14.20.lq , 14.20.mr key words : triply heavy baryon states , qcd sum rules .
And you have already written the first three sentences of the full article: by this time , the @xmath4 and @xmath5 antitriplet charmed baryon states ( @xmath6 , @xmath7 , @xmath8 and ( @xmath9 , @xmath10 , @xmath11 , and the @xmath4 and @xmath12 sextet charmed baryon states ( @xmath13 ) and ( @xmath14 ) have been observed , while the @xmath15-wave bottom baryon states are far from complete , only the @xmath16 , @xmath17 , @xmath18 , @xmath19 , @xmath20 , @xmath21 , @xmath22 , @xmath23 and @xmath24 have been observed @xcite . in 2002 ,
the selex collaboration reported the first observation of the doubly charmed baryon state @xmath25 in the decay @xmath26 @xcite , and confirmed it later in the decay @xmath27 @xcite .
however , the babar collaboration observed no evidence for the @xmath28 in the @xmath29 , @xmath30 decay modes and for the @xmath31 in the @xmath32 , @xmath33 decay modes , and the belle collaboration observed no evidence for the @xmath28 in the @xmath29 decay mode @xcite ..
Please generate the next two sentences of the article | there are no experimental signals for the triply heavy baryon states , we expect that the large hadron collider ( lhc ) will provide us with the whole heavy , doubly heavy and triply heavy baryon states @xcite .
the triply heavy baryon states and heavy quarkonium states play an important role in understanding the heavy quark dynamics at the hadronic scale due to the absence of the light quark contaminations , and serve as an excellent subject in studying the interplay between the perturbative and nonperturbative qcd . on the other hand , |
8,864 | Suppose that you have an abstract for a scientific paper: using ccd photometry obtained by the eros collaboration in 1991 - 1993 , we have discovered an lmc variable star with a light curve that is oscillating with a mean period of @xmath0 days and an amplitude of @xmath1 0.3 mag .
the oscillations appear with irregular amplitude variations .
the fourier spectrum shows that the pulsation of this star is phase locked between two modes of frequencies @xmath2 and 1.5@xmath3 .
moreover , this object has strong @xmath4 and @xmath5 emission lines and neutral lines of helium that suggest a spectral type between late o and early b. in a preliminary analysis , we derive a luminosity of @xmath6 and an effective temperature in the range @xmath7 . * a @xmath0 days star with two phase - locked * 0.5 truecm * modes of pulsation in the eros database * 1.0 truecm 1.0 truecm authors : j.p .
beaulieu@xmath8 , r.buchler@xmath9 , m.j.goupil@xmath10 , z.kollath@xmath11 , @xmath12 kapteyn laboratorium , postbus 800 , 9700 av groningen , the netherlands .
+ @xmath13 institut dastrophysique de paris , cnrs , 98bis boulevard arago , f75014 paris , france .
+ @xmath9 physics department , university of florida , gainesville , fl 32611 , usa .
+ @xmath10 dasgal , observatoire de paris , meudon 92195 , france .
+ @xmath14 konkoly observatory , budapest , hungary . .
And you have already written the first three sentences of the full article: ccd photometry was obtained in a field of 0.5 square degree in the bar of the lmc between 1991 - 1993 for eros .
about 2500 images spanning @xmath1130 days were taken in two broad bandpass filters @xmath15 and @xmath16 centered respectively on 490 and 670 nm in the 9192 campaign , and 5500 images were taken of the same field with a pair of very similar filters ( @xmath17 ) for the 1992 - 1993 campaign .
we have systematically searched the eros database for variable stars using the modified periodogram technique@xcite@xcite and the aov method@xcite . among the hundredth detected variable stars , we have discovered a bright lmc variable star ( @xmath18m@xmath19 , equinox 2000.0 ) with a period of @xmath0 days and a particular behaviour , a clear alternance between cycles with larger and smaller amplitudes ( fig 1 ) ..
Please generate the next two sentences of the article | a fourier fit with 8 independent frequencies leads to a spectrum with two dominant frequencies at @xmath2=825.69 phz and at 1.5003@xmath3 ( fig.2 ) .
this suggests that the pulsation of this star is phase locked between two modes of frequencies @xmath2 and 1.5@xmath3 . from the photometry , |
8,865 | Suppose that you have an abstract for a scientific paper: the most popular hypothesis testing procedure , the likelihood ratio test , is known to be highly non - robust in many real situations .
@xcite provided an alternative robust procedure of hypothesis testing based on the density power divergence ; however , although the robustness properties of the latter test were intuitively argued for by the authors together with extensive empirical substantiation of the same , no theoretical robustness properties were presented in that work . in the present paper
we will consider a more general class of tests which forms a superfamily of the procedures described by @xcite .
this superfamily derives from the class of @xmath0-divergences recently proposed by @xcite . in this context
we theoretically prove several robustness results of the new class of tests and illustrate them in the normal model .
all the theoretical robustness properties of the @xcite proposal follows as special cases of our results .
hypothesis testing , robustness , @xmath0-divergence . .
And you have already written the first three sentences of the full article: hypothesis testing is a very important component of statistical inference ; it helps us to systematically explore the veracity of an unsubstantiated claim on the basis of observed data in a real life experiment .
the philosophy of the statistical hypothesis testing was mainly developed in the early decades of twentieth century by fisher and neyman and pearson @xcite ; since then the theory has evolved in many directions through the contributions of several later researchers . yet
the classical likelihood ratio test ( lrt ) proposed by @xcite and formalized later by @xcite still remains our canonical hypothesis testing tool , which is used widely by the practitioners in all scenarios of human endeavor ..
Please generate the next two sentences of the article | this test can be easily performed for most statistical models and satisfies several asymptotic optimality criteria . however , as in the case of maximum likelihood estimator ( mle ) in the estimation context , the lrt also has serious robustness problems under misspecification of models and/or presence of outliers .
there have been several attempts to develop robust tests of hypotheses having optimal properties similar to the lrt . |
8,866 | Suppose that you have an abstract for a scientific paper: fluids confined within narrow channels exhibit a variety of phases and phase transitions associated with their reduced dimensionality . in this review paper
, we illustrate the crossover from quasi - one dimensional to higher effective dimensionality behavior of fluids adsorbed within different carbon nanotubes geometries . in the single nanotube geometry
, no phase transitions can occur at finite temperature .
instead , we identify a crossover from a quasi - one dimensional to a two dimensional behavior of the adsorbate . in bundles of nanotubes , phase transitions at finite
temperature arise from the transverse coupling of interactions between channels . .
And you have already written the first three sentences of the full article: one of the most interesting topics within modern condensed matter physics is that of phenomena in reduced dimensionality , resulting from some degree of spatial localization of the particles comprising a system.@xcite for example , chemists , materials scientists and physicists have created and explored numerous physical systems in which atoms and molecules are confined within quasi - one dimensional ( q1d ) environments .
the variety of these systems is remarkable , such as the peapod geometry , _ i.e. _ , a line of buckyballs within a carbon nanotube,@xcite fluids within artificial materials created by templating @xcite and q1d optical lattices created by laser fields.@xcite unfortunately , as far as we know , there exists no comprehensive review of this general problem , although many relevant subfields have been summarized.@xcite the present paper addresses a small subset of this exciting research field .
specifically , we consider problems involving fluids , both classical and quantum , confined within q1d channels , the focus of our group s research during the last decade.@xcite here , the term q1d refers to a system in which particles move in an external potential field @xmath0 which is either constant or slowly varying in _ one _ direction ( @xmath1 ) , while @xmath2(*r * ) is strongly localizing in the two other ( transverse ) directions . in the case of quantum particles , for which the transverse spectrum is discrete , one expects that the corresponding degrees of freedom are frozen out at low temperature ( @xmath3 ) ; transverse excitation does occur at higher @xmath3 , as determined by the gaps in the transverse spectrum of states ..
Please generate the next two sentences of the article | this plausible expectation is borne out in some cases , but we shall see that there can be dramatic consequences of the transverse degrees of freedom in other cases , even at low @xmath3 .
one of the many exciting aspects of strictly 1d physics is its susceptibility to weak perturbations . |
8,867 | Suppose that you have an abstract for a scientific paper: the violation of local uncertainty relations is a valuable tool for detecting entanglement , especially in multi - dimensional systems .
the orbital angular momentum of light provides such a multi - dimensional system .
we study quantum correlations for the conjugate variables of orbital angular momentum and angular position .
we determine an experimentally testable criterion for the demonstration of an angular version of the epr paradox . for the interpretation of future experimental results from our proposed setup ,
we include a model for the indeterminacies inherent to the angular position measurement . for this measurement angular apertures
are used to determine the probability density of the angle .
we show that for a class of aperture functions a demonstration of an angular epr paradox , according to our criterion , is to be expected . .
And you have already written the first three sentences of the full article: experiments on the orbital angular momentum [ oam ] of light confirmed recently an uncertainty principle for angular position and angular momentum @xcite . whereas for separable quantum states uncertainty principles limit the accuracy for measurements of non - commuting observables , inseparable or entangled states may apparently overcome these limits .
this was first discussed by einstein , podolsky and rosen in their famous _ gedankenexperiment _
@xcite and led to the formulation of the epr paradox @xcite ..
Please generate the next two sentences of the article | the implications of the epr paradox have been tested mainly on optical systems , e.g. on the polarisation of photons @xcite , quadrature phase components @xcite or directly on the optical version of epr s original example , the linear momentum and linear position of photons @xcite .
the relation between oam and its conjugate variable , the angular position , is fundamentally different from these systems , because oam is a discrete quantum observable of infinite dimension and the angular position is continuous and bounded . |
8,868 | Suppose that you have an abstract for a scientific paper: we introduce definitions of contact blow up from several perspectives .
such different approaches to the contact blow up are related .
we prove that the contact topology coincides in the case of blow
ups along transverse embedded loops . .
And you have already written the first three sentences of the full article: in his book _ partial differential relations _
@xcite , m. gromov proposed a definition of the blow up operation in the contact category , see exercise ( c ) on page 343 .
this article discusses this definition as well as related constructions ..
Please generate the next two sentences of the article | + let @xmath0 be a smooth manifold and @xmath1 an embedded submanifold
. the normal bundle of @xmath2 in @xmath0 will be denoted by @xmath3 . recall that it is defined through the short exact sequence of smooth vector bundles over @xmath4 @xmath5 given a complex vector bundle @xmath6 , we denote by @xmath7 the fiberwise projectivization of @xmath8 . + suppose the normal bundle @xmath3 is a complex bundle , then we may produce a manifold @xmath9 , the topological blow up of @xmath0 along @xmath4 . |
8,869 | Suppose that you have an abstract for a scientific paper: due to the confined focal length of optical sensors , focusing all objects in a scene with a single sensor is a difficult task . to handle such a situation ,
image fusion methods are used in multi - focus environment .
discrete cosine transform ( dct ) is a widely used image compression transform , image fusion in dct domain is an efficient method .
this paper presents a low complexity approach for multi - focus image fusion and its vlsi implementation using dct .
the proposed method is evaluated using reference/ non - reference fusion measure criteria and the obtained results asserts it s effectiveness .
the proposed method uses only @xmath0 addition to fuse the two @xmath1 image block and consumes only 250 mw power at 200 mhz operating frequency .
the maximum synthesized frequency on fpga is found to be 221 mhz and consumes 42% of fpga resources .
the proposed method consumes very less power and can process 4k resolution images at the rate of 60 frames per second which makes the hardware suitable for handheld portable devices such as camera module and wireless image sensors .
discrete cosine transform , multi - focus image , image fusion , vlsi implementation . .
And you have already written the first three sentences of the full article: a blurred image carries less information than a sharp image . due to the confined focal depth , it is hard to capture an image in which all objects / areas of the scene appear quite sharp . only the objects of a scene that are near the focus plane or at the focus plane appear sharp . to handle such situations the images
are acquired using a number of imaging sensors or with multi focus imaging . after taking images , high contrast regions from each of the acquired images
are selected and fused together to create an image that is in focus everywhere ..
Please generate the next two sentences of the article | the fusion process reduces the uncertainty and redundancy from the source images .
there are a number of benefits of using the fusion process including reduced uncertainty , wider temporal and spatial coverage and improved reliability @xcite . |
8,870 | Suppose that you have an abstract for a scientific paper: we present a simple , pedagogical introduction to the statistics of extreme values .
motivated by a string of record high temperatures in december 1998 , we consider the distribution , averages and lifetimes for a simplified model of such `` records .
'' our `` data '' are sequences of independent random numbers all of which are generated from the same probability distribution .
a remarkable universality emerges : a number of results , including the lifetime histogram , are universal , that is , independent of the underlying distribution . .
And you have already written the first three sentences of the full article: in december 1998 , in the aftermath of el nino and its companion , la nina , the weather in the roanoke , virginia , area was unusually mild .
weather data have been collected here since 1934 , and record highs and lows for any particular day are known . as part of the daily weather forecasts ,
local tv stations report these record values and compare them to the highest and lowest temperature values of the day ..
Please generate the next two sentences of the article | remarkably , during the _ nine _ days from november 29 to december 7 , 1998 , the previous record highs were _ broken five times and tied once_!@xcite one might wonder , as we did , how frequently such a series of records could possibly occur .
when only few weather data are available , such as in the early years of record keeping , it is obviously quite easy to experience new extremes . |
8,871 | Suppose that you have an abstract for a scientific paper: studies of event shape observables at petra and lep energies are presented .
previously published determinations of the strong coupling constant @xmath0 at @xmath1 = 35 and 44 gev are complemented using new resummed qcd calculations for the @xmath2 parameter and improved calculations for the jet broadening variables @xmath3 and @xmath4 which recently became available .
furthermore , recently predicted power corrections to the differential distributions of these observables are investigated . in this study ,
e@xmath5e@xmath6 data between @xmath1 = 35 and 183 gev are considered .
= cmss24 at 20truept = cmss14 at 14truept = cmss10 at 12truept = cmss10 at 10truept = cmss8 at 8truept to 245 mm to * event shapes from jade data + and + studies of power corrections * pedro a. movilla fernndez + iii .
institut , technische hochschule aachen + d-52056 aachen , germany .
And you have already written the first three sentences of the full article: data from the intermediate energy region of e@xmath5e@xmath6 annihilation , as provided by the jade experiment at petra , allow significant tests of perturbative and non - perturbative aspects of quantum chromodynamics ( qcd ) .
this was stressed in a recently published analysis of jade data @xcite where determinations of the strong coupling constant @xmath0 at @xmath1 = 22 to 44 gev were presented , which are the most precise ones at petra energies . since the analysis is based on event shape observables for which resummed qcd predictions @xcite ( nlla )
were developed long after the petra shutdown , the theoretical uncertainties of previous measurements @xcite could be reduced significantly . by applying lep - established techniques of estimating experimental and theoretical systematics ,.
Please generate the next two sentences of the article | the running of @xmath0 was tested _
consistently _ within a large range of energy scales @xcite . a reliable estimation of the higher order uncertainties of the predictions , individually for each observable , is supported by considering as many observables as possible . |
8,872 | Suppose that you have an abstract for a scientific paper: low mass vector meson ( @xmath7 ) production provides key information on the hot and dense state of strongly interacting matter produced in high - energy heavy ion collisions . among them , strangeness enhancement can be accessed through the measurement of @xmath0 meson production , while the measurement of the @xmath8 spectral function can be used to reveal in - medium modifications of hadron properties close to the qcd phase boundary .
vector meson production in pp collisions provides a reference for these studies .
moreover , it is interesting by itself , since it can be used to tune particle production models in the unexplored lhc energy range .
the alice experiment at the lhc can access vector mesons produced at forward rapidity through their decays in muon pairs , and at central rapidity in the di - electron decay channel .
the detector is fully described in @xcite . in this paper ,
results from the analysis of the data collected during the 2010 pp run at @xmath2 tev are reported .
the measurement in the dimuon channel was performed using the forward muon spectrometer , that consists of an absorber acting as muon filter , a set of cathod pad chambers ( five stations , each one composed of two chambers ) for the track reconstruction in a dipole field , two stations of two resistive plate chambers for the muon trigger , two absorbers and an iron wall acting as a muon filter . the data sample used for the analysis in the dimuon channel amounts to an integrated luminosity of approximately 85 nb@xmath9 .
since only a fraction of the data contained the full information relevant for the extraction of the integrated luminosity , a subsample corresponding to @xmath10 was used for the measurement of the @xmath0 cross section , while the full sample was used to extract the @xmath11 distribution .
muon pairs were selected asking that each muon track reconstructed in the tracking chambers matches the corresponding tracklet in the trigger stations in the position in the ( x - y ) plane....
And you have already written the first three sentences of the full article: 10 k. aamodt et al .
( alice collaboration ) , j. instrum . * 3 * , s08002 ( 2008 ) k. nakamura et al .
( particle data group ) , j. phys ..
Please generate the next two sentences of the article | * g37 * , 075021 ( 2010 ) k. oyama et al .
( alice collaboration ) , proc . of the workshop |
8,873 | Suppose that you have an abstract for a scientific paper: we provide a description of the interpolating and sampling sequences on a space of holomorphic functions with a uniform growth restriction defined on finite riemann surfaces . .
And you have already written the first three sentences of the full article: let @xmath0 be an open finite riemann surface endowed with the poincar ( hyperbolic ) metric .
we will study some properties of holomorphic functions in the riemann surface with uniform growth control . namely we will deal with the banach space @xmath1 of holomorphic functions in @xmath0 such that @xmath2 where @xmath3 is a given subharmonic function that controls the growth of the functions in the space .
the fact that @xmath3 is subharmonic is a natural assumption on the weight that limits the growth since any other growth control given by a weight @xmath4 , @xmath5 can be replaced by an equivalent subharmonic function because @xmath6 is a subharmonic function and @xmath7 with equality of norms , latexmath:[$\sup_s |f|e^{-\psi}= \sup_s we have fixed a metric ..
Please generate the next two sentences of the article | it is then natural to restrict the possible weights @xmath3 , in a way that the functions in @xmath9 oscillate in a controlled way when the points are nearby in the poincar metric .
this is achieved for instance by assuming that @xmath3 has bounded laplacian ( the laplace - beltrami operator with respect to the hyperbolic measure ) . |
8,874 | Suppose that you have an abstract for a scientific paper: we present a formalism that simultaneously incorporates the effect of quantum tunneling and spin diffusion on spin hall magnetoresistance observed in normal metal / ferromagnetic insulator bilayers ( such as pt / y@xmath0fe@xmath1o@xmath2 ) and normal metal / ferromagnetic metal bilayers ( such as pt / co ) , in which the angle of magnetization influences the magnetoresistance of the normal metal . in the normal metal side
the spin diffusion is known to affect the landscape of the spin accumulation caused by spin hall effect and subsequently the magnetoresistance , while on the ferromagnet side the quantum tunneling effect is detrimental to the interface spin current which also affects the spin accumulation .
the influence of generic material properties such as spin diffusion length , layer thickness , interface coupling , and insulating gap can be quantified in a unified manner , and experiments that reveal the quantum feature of the magnetoresistance are suggested . .
And you have already written the first three sentences of the full article: the electrical control of magnetization dynamics has been a central issue in the field of spintronics@xcite , owing to its possible applications in magnetic memory devices with low power consumption .
a particularly promising mechanism for the electrical control is to utilize the spin hall effect@xcite ( she ) in a normal metal ( nm ) , such as pt or ta , to convert an electric current into a spin current , and subsequently to magnetization dynamics in an adjacent magnet via mechanisms such as spin - transfer torque@xcite ( stt ) . in reverse , the inverse spin hall effect@xcite ( ishe ) can convert the spin current generated by certain means , for instance spin pumping@xcite , into an electric signal .
a particularly intriguing phenomenon that involves both she and ishe is the spin hall magnetoresistance@xcite ( smr ) , in which a charge current in an nm causes a spin accumulation at the edge of the sample due to she , yielding a finite spin current at the interface to a ferromagnet . through ishe.
Please generate the next two sentences of the article | , the spin current gives an electromotive force along the original charge current , effectively changing the magnetoresistance of the nm .
the two major ingredients that determine smr are the spin diffusion@xcite in the nm and the spin current at the nm / ferromagnet interface . |
8,875 | Suppose that you have an abstract for a scientific paper: in this paper we study dual bases functions in subspaces .
these are bases which are dual to functionals on larger linear space .
our goal is construct and derive properties of certain bases obtained from the construction , with primary focus on polynomial spaces in b - form .
when they exist , our bases are always affine ( not convex ) , and we define a symmetric configuration that converges to lagrange polynomial bases . because of affineness of our bases , we are able to derive certain approximation theoretic results involving quasi - interpolation and a bernstein - type operator . in a broad sense
, it is the aim of this paper to present a new way to view approximation problems in subspaces . in subsequent work
, we will apply our results to dual bases in subspaces of spline and multivariate polynomial spaces , and apply this to the construction of blended function approximants used for approximation in the sum of certain tensor product spaces .
[ multiblock footnote omitted ] .
And you have already written the first three sentences of the full article: let @xmath0 be a finite dimensional vector spaces ( of dimension @xmath1 )
. of fundamental importance is the basis .
there are various reasons to choose a particular basis , and each basis has advantages and disadvantages ..
Please generate the next two sentences of the article | often it is the action of certain functionals that lends importance to a particular basis .
for example , the lagrange basis is important because it is dual to point evaluation . in general , |
8,876 | Suppose that you have an abstract for a scientific paper: let @xmath0 be a hyperbolic surface .
we investigate the topology of the space of all curves on @xmath0 which start and end at given points in given directions , and whose curvatures are constrained to lie in a given interval @xmath1 .
these spaces fall into four qualitatively distinct classes , according to whether @xmath1 contains , overlaps , is disjoint from , or contained in the interval @xmath2 $ ] .
their homotopy type is computed in the latter two cases .
= 1 .
And you have already written the first three sentences of the full article: a curve on a surface @xmath0 is said to be if it has a continuous and nonvanishing derivative . consider two such curves whose curvatures take values in some given interval , starting in the same direction ( prescribed by a unit vector tangent to @xmath0 ) and ending in another prescribed direction .
it is a natural problem to determine whether one curve can be deformed into the other while keeping end - directions fixed and respecting the curvature bounds . from another viewpoint
, one is asking for a characterization of the connected components of the space of all such curves ..
Please generate the next two sentences of the article | more ambitiously , what is its homotopy or homeomorphism type ?
the answer can be unexpectedly interesting , and it is closely linked to the geometry of @xmath0 . in this article |
8,877 | Suppose that you have an abstract for a scientific paper: various commercial coated conductors were irradiated with fast neutrons in order to introduce randomly distributed , uncorrelated defects which increase the critical current density , @xmath0 , in a wide temperature and field range . the @xmath0-anisotropy is significantly reduced and the angular dependence of @xmath0 does not obey the anisotropic scaling approach . these defects enhance the irreversibility line in not fully optimized tapes , but they do not in state - of - the - art conductors .
neutron irradiation provides a clear distinction between the low field region , where @xmath0 is limited by the grain boundaries , and the high field region , where depinning leads to dissipation . .
And you have already written the first three sentences of the full article: neutron irradiation is certainly not practical for improving the properties of long length commercial superconductors , but a very efficient tool for benchmarking and investigating flux pinning .
it helps understanding vortex physics @xcite and limitations of the current flow @xcite .
efficient pinning centers are introduced , whose size perfectly matches the coherence length of yba@xmath1cu@xmath2o@xmath3 ( ybco ) ..
Please generate the next two sentences of the article | they improve the critical currents , if the density of defects was originally too small , but diminish them , if the total defect concentration becomes too high .
although the resulting defect structure is not perfectly well defined , since only the density of the largest defects , the collision cascades , is known @xcite and many smaller defects of unknown density are produced @xcite , it is clearly established that all defects are randomly distributed and uncorrelated , i.e. , without a preferred orientation . |
8,878 | Suppose that you have an abstract for a scientific paper: an oscillating universe cycles through a series of expansions and contractions . we propose a model in which `` phantom '' energy with a supernegative pressure ( @xmath0 ) grows rapidly and dominates the late - time expanding phase .
the universe s energy density is so large that the effects of quantum gravity are important at both the beginning and the end of each expansion ( or contraction ) .
the bounce can be caused by high energy modifications to the friedmann equation , which make the cosmology nonsingular .
the classic black hole overproduction of oscillating universes is resolved due to their destruction by the phantom energy . .
And you have already written the first three sentences of the full article: the arrow of time is intimately connected to the entropy of the universe .
the second law of thermodynamics inexorably drives us to ever increasing entropy , yet we live in neither a situation of maximal entropy ( a black hole ) nor in a minimal entropy universe .
apparently we thrive in the current `` medium entropy '' universe ..
Please generate the next two sentences of the article | how is this possible ? in this conference , two possible explanations for this homogenous and isotropic universe we live in have been discussed : special initial conditions or eternal inflation combined with anthropic arguments .
in fact , there is a third option : cyclicity . here |
8,879 | Suppose that you have an abstract for a scientific paper: we introduce a parallel gpu implementation of the simple linear iterative clustering ( slic ) superpixel segmentation . using a single graphic card
, our implementation achieves speedups of up to @xmath0 from the standard sequential implementation .
our implementation is fully compatible with the standard sequential implementation and the software is now available online and is open source . .
And you have already written the first three sentences of the full article: superpixels are regions of pixels grouped in some perceptually meaningful way , usually following colour or boundary cues .
they are designed to produce a simpler and more compact representation for an image , while keeping its semantic meaning intact .
superpixel segmentation is used most often as an image preprocessing step , with a view towards reducing computational complexity for subsequent processing steps ..
Please generate the next two sentences of the article | the term _ superpixel _ , along with the first notable superpixel algorithm , was introduced by @xcite .
many algorithms followed , using various types of image features , various optimisation strategies and various implementations techniques . |
8,880 | Suppose that you have an abstract for a scientific paper: pulmonary embolism ( pe ) is a common and potentially lethal condition .
most patients die within the first few hours from the event . despite diagnostic advances , delays and underdiagnosis in pe
are common .
moreover , many investigations pursued in the suspect of pe result negative and no more than 10@xmath0 of the pulmonary angio - ct scan performed to confirm pe confirm the suspected diagnosis . to increase the diagnostic performance in pe , current diagnostic work - up of patients with suspected acute pulmonary embolism usually starts with the assessment of clinical pretest probability using plasma d - dimer measurement and clinical prediction rules .
one of the most validated and widely used clinical decision rules are the wells and geneva revised scores .
however , both indices have limitations .
we aimed to develop a new clinical prediction rule ( cpr ) for pe based on a new approach for features selection based on topological concepts and artificial neural network .
filter or wrapper methods for features reduction can not be applied to our dataset : the application of these algorithms can only be performed on datasets without missing data . alternatively , eliminating rows with null values in the dataset would reduce the sample size significantly and result in a covariance matrix that is singular .
instead , we applied topological data analysis ( tda ) to overcome the hurdle of processing datasets with null values missing data .
a topological network was developed using the iris software ( ayasdi , inc .
, palo alto ) .
the pe patient topology identified two flares in the pathological group and hence two distinct clusters of pe patient populations .
additionally , the topological netowrk detected several sub - groups among healthy patients that likely are affected with non - pe diseases . to be diagnosed properly even though they are not affected by pe , in a next study we will introduce also the survival curves for the patients .
tda was further utilized to identify....
And you have already written the first three sentences of the full article: clinical prediction rule ( cpr ) , pulmonary embolism , topological data analysis , artificial neural network ( ann ) , computer aided detection cad
several statistical and machine learning techniques have been proposed in the literature to deal with output of implicit or explicit rules and good classification performance @xcite .
most available techniques , such as linear discriminant approaches , multilayer perceptrons or support vector machines , are able to achieve a good degree of provisional accuracy but these methods lack accuraccy sufficient for the implementation of computer - aided diagnosis ( cad ) for pulmonary embolism diagnosis ..
Please generate the next two sentences of the article | different studies have been developed for cad system predicting development of pe in patients .
tang et al used data from the shangai xin hua hospital , tourassi et al and patil s used the data collected from the collaborative study of the _ prospective investigation of pulmonary embolism diagnosis ( pioped ) _ and built neural network @xcite . to improve the performance of a cad we built a new system based on topological data analysis and statistical approach for features selection to define the input space for theartificial neural network . |
8,881 | Suppose that you have an abstract for a scientific paper: the planned rhenium @xmath0-decay experiment , called the `` microcalorimeter arrays for a rhenium experiment '' ( mare ) , might probe the absolute mass scale of neutrinos with the same sensitivity as the karlsruhe tritium neutrino mass ( katrin ) experiment , which will take commissioning data in 2011 and will proceed for 5 years . we present the energy distribution of emitted electrons for the first unique forbidden @xmath0-decay of @xmath1 .
it is found that the @xmath2-wave emission of electron dominates over the @xmath3-wave . by assuming mixing of three neutrinos the kurie function for the rhenium @xmath0-decay
is derived .
it is shown that the kurie plot near the endpoint is within a good accuracy linear in the limit of massless neutrinos like the kurie plot of the superallowed @xmath0-decay of @xmath4 . .
And you have already written the first three sentences of the full article: the recent atmospheric , solar , reactor and accelerator neutrino experiments have convinced us that neutrinos are massive particles .
however , the problem of absolute values of their masses is still waiting for a solution .
neutrino oscillations depend on the differences of neutrino masses , not on their absolute values.
Please generate the next two sentences of the article | . apparently three kinds of neutrino experiments have a chance to determine the light neutrino masses : i ) cosmological measurements , ii ) the tritium and rhenium single @xmath0-decay experiments , iii ) neutrinoless double @xmath0-decay experiments .
the measurement of the electron spectrum in @xmath0-decays provides a robust direct determination of the values of neutrino masses . in practice , |
8,882 | Suppose that you have an abstract for a scientific paper: the hubble constant can be constrained using the time delays between multiple images of gravitationally lensed sources . in some notable cases , typical lensing analyses assuming isothermal galaxy density profiles produce low values for the hubble constant , inconsistent with the result of the hst key project ( 72 @xmath0 8 kms@xmath1 mpc@xmath1 ) .
possible systematics in the values of the hubble constant derived from galaxy lensing systems can result from a number of factors , e.g. neglect of environmental effects , assumption of isothermality , or contamination by line - of - sight structures .
one additional potentially important factor is the triaxial structure of the lensing galaxy halo ; most lens models account for halo shape simply by perturbing the projected spherical lensing potential , an approximation that is often necessary but that is inadequate at the levels of triaxiality predicted in the cdm paradigm . to quantify the potential error introduced by this assumption in estimates of the hubble parameter
, we strongly lens a distant galaxy through a sample of triaxial softened isothermal halos and use an mcmc method to constrain the lensing halo profile and the hubble parameter from the resulting multiple image systems .
we explore the major degeneracies between the hubble parameter and several parameters of the lensing model , finding that without a way to accurately break these degeneracies accurate estimates of the hubble parameter are not possible .
crucially , we find that triaxiality does _ not _ significantly bias estimates of the hubble constant , and offer an analytic explanation for this behaviour in the case of isothermal profiles .
neglected triaxial halo shape can not contribute to the low hubble constant values derived in a number of galaxy lens systems .
[ firstpage ] gravitational lensing galaxies : fundamental parameters galaxies : halos cosmology : cosmological parameters cosmology : theory dark matter .
And you have already written the first three sentences of the full article: gravitationally lensed , multiply imaged radio source time delays are used to constrain the hubble constant .
lensing analyses produce a range of values , some of which are significantly lower than the result of the hst key project ( 72 @xmath0 8 kms@xmath1 mpc@xmath1 ) ; @xcite offers an excellent summary of the current state of the field .
further , although there is a general agreement upon isothermality from a number of differently motivated studies ( e.g. @xcite ; @xcite ; @xcite ; @xcite ; @xcite ; @xcite ; @xcite ) , modelling of a number of systems ( e.g. pg1115 + 080 , b1600 + 434 , he2149 - 2745 , and sbs1520 + 530 ) has shown that these prefer more centrally concentrated , non - isothermal , density profiles @xcite ..
Please generate the next two sentences of the article | the slope of the lensing density profile and the value of hubble constant are heavily degenerate , and the number of constraints from galaxy lens systems small , making it unclear whether the inconsistencies in slope and hubble constant values indicate flaws in the measurement of both or only one of the two quantities .
while some recent statistical studies ( e.g. @xcite ) find values consistent with the consensus value , some unexplained inconsistencies remain among the varied results across the field , and whether these stem primarily from external environmental effects , intrinsic physical attributes of the lensing galaxy or universe , or differences in modeling techniques is still unclear . |
8,883 | Suppose that you have an abstract for a scientific paper: we study the blackbody spectrum from slabs of three - dimensional metallodielectric photonic crystals consisting of gold nanoparticles using an ab initio multiple - scattering method .
the spectra are calculated for different photonic - crystal slab thicknesses , particle radii and hosting materials .
we find in particular that such crystals exhibit a broadband emission spectrum above a specific cutoff frequency with emissivity of about 90% .
the studied photonic crystals can be used as efficient selective emitters and can therefore find application in thermophotovoltaics and sensing .
the main feature of photonic crystals is the ability to tailor the photon density of states and this way control the spontaneous emission of light , aiming at the realization of new optoelectronic devices . in this context
, there has been considerable effort to design and fabricate photonic crystals which allow for control of thermal emission of light , i.e. thermally driven spontaneous emission , promising applications in imaging , sensing and most importantly , in thermophotovoltaics ( tpv ) .
@xcite control of thermal emission can also be achieved by means of microstructured engineering on silicon @xcite or metal surfaces . @xcite depending on the type of application , photonic crystals and structured surfaces can act as narrow- or wide - band , directional or isotropic thermal emitters .
for example , in tpv applications @xcite a quasi - monochromatic emission is preferable whilst in radiation cooling @xcite a broad emission spectrum is desired . in this work
we investigate the emission properties of three - dimensional metallodielectric photonic crystals consisting of gold nanoparticles .
we find , in particular , that the emission spectrum of these crystals can be such that photons are emitted in all directions only when their energies lie above a specific cutoff frequency , with emissivity as large as 90% .
photonic crystals of spherical scatterers have been theoretically studied using....
And you have already written the first three sentences of the full article: this work was supported by the ` karatheodory ' research fund of university of patras . 00 c. m. cornelius and j. p. dowling , , 4736 ( 1999 ) .
s. y. lin , j. g. fleming , e. chow , j. bur , k. k. choi , and a. goldberg , , r2243 ( 2000 ) . j. g. fleming , s. y. lin , i. el - kady , r. biswas , and k. m. ho , , 52 ( 2002 ) . m. u. pralle , n. moelders , m.p .
mcneal , i. puscasu , a. c. greenwald , j. t. daly , e. a. johnson , t. george , d. s. choi , i. el - kady , and r. biswas , , 4685 ( 2002 ) ..
Please generate the next two sentences of the article | s. y. lin , j. g. fleming , and i. el - kady , , 1909 ( 2003 ) .
i. celanovic , f. o sullivan , m. ilak , j. kassakian , and d. perreault , , 863 ( 2004 ) . |
8,884 | Suppose that you have an abstract for a scientific paper: in this paper it is demonstrated that based on two - dimensional distributions in semi - inclusive deep inelastic scattering ( sidis ) data , obtained recently by the hermes experiment at desy on different nuclei , which contains data for charged pions produced in @xmath0 slices as a function of @xmath1 , and in a @xmath1 slices as a function of @xmath0 , it it is possible to parametrise a ratio of multiplicities on nucleus and deuterium ( per nucleon ) @xmath2 in a form of a function of a single variable @xmath3 , which has the physical meaning of the formation time of hadron .
we call this effect @xmath3 scaling .
@xmath3 is a function of two variables @xmath1 and @xmath0 .
it is also shown that @xmath2 can be presented in a form of a linear polynomial of @xmath3 , @xmath4 + @xmath5 , where parameters @xmath4 and @xmath6 do not depend on @xmath1 and @xmath0 . .
And you have already written the first three sentences of the full article: hadronization is the process through which partons , created in an elementary interaction , turn into the hadrons .
experimentally the hadronization process in free space ( vacuum ) has been studied extensively in @xmath7 annihilation and in semi - inclusive lepton - proton deep inelastic scattering ( dis ) . as a result , the spectra of hadrons produced and their kinematical dependences are rather well known . however
, little is known about the space - time evolution of the process , because the products of this process can only be observed in a detector that is separated from the reaction point by a macroscopic distance ..
Please generate the next two sentences of the article | it is worth to mention that according to theoretical estimates the hadronization process occurs over length scales that vary from less than a femtometer to several tens of femtometers .
the nuclear medium can serve as a detector located directly at the place where microscopic interaction happens . |
8,885 | Suppose that you have an abstract for a scientific paper: for nonnegative real numbers @xmath0 , @xmath1 , @xmath2 , @xmath3 , @xmath4 and @xmath5 such that @xmath6 and @xmath7 , the difference equation @xmath8 has a unique positive equilibrium . a proof is given here for the following statements : theorem 1 .
_ for every choice of positive parameters @xmath0 , @xmath1 , @xmath2 , @xmath3 , @xmath4 and @xmath5 , all solutions to the difference equation @xmath9 converge to the positive equilibrium or to a prime period - two solution .
_ theorem 2 .
_ for every choice of positive parameters @xmath0 , @xmath1 , @xmath2 , @xmath3 , @xmath4 and @xmath5 , all solutions to the difference equation @xmath10 converge to the positive equilibrium or to a prime period - two solution .
_ difference equation , rational , global behavior , global attractivity , period - two solution . .
And you have already written the first three sentences of the full article: in their book @xcite , m. kulenovi and g. ladas initiated a systematic study of the difference equation @xmath11 for nonnegative real numbers @xmath0 , @xmath1 , @xmath2 , @xmath3 , @xmath4 and @xmath5 such that @xmath6 and @xmath7 , and for nonnegative or positive initial conditions @xmath12 , @xmath13 . under these conditions , ( [ eq : 3 - 3 orig . ] ) has a unique positive equilibrium .
one of their main ideas in this undertaking was to make the task more manageable by considering separate cases when one or more of the parameters in ( [ eq : 3 - 3 orig . ] ) is zero .
the need for this strategy is made apparent by cases such as the well known _.
Please generate the next two sentences of the article | lyness equation _
@xcite , @xcite , @xcite . @xmath14 whose dynamics differ significantly from other equations in this class . |
8,886 | Suppose that you have an abstract for a scientific paper: an appended sector of two octet - colored scalars , each an electroweak doublet , is an interesting extension of the simple two higgs doublet model motivated by the minimal flavor violation .
their rich cp violating interaction gives rise to a sizable electron electric dipole moment , besides the quark electric dipole moment via the two - loop contribution of barr - zee mechanism .
* electron electric dipole moment induced by octet - colored scalars * jae ho heo and wai - yee keung physics department , university of illinois at chicago , chicago , il 60607 - 7059 .
And you have already written the first three sentences of the full article: the flavor diversity in the electroweak interaction continues to attract theoretical curiosity for new physics beyond the standard model .
pioneer work of ref.@xcite has shown a natural mechanism to suppress the unwanted neutral flavor changing process mediated by the higgs exchange .
recent activities address the general structure of the minimal flavor violation ( mfv ) @xcite ..
Please generate the next two sentences of the article | it is noticed that octet - colored scalars are able to respect mfv .
the general yukawa interaction is given by @xmath0 where @xmath1 refers to the three families of left - handed quark doublets , and @xmath2 and @xmath3 the three families of the up - type and down - type right - handed quark singlets . |
8,887 | Suppose that you have an abstract for a scientific paper: rapid _ ubvri _ photometry of the ultracompact low - mass x - ray binary ( lmxb ) pulsar 4u 162667/kz tra has detected 130.4 mhz ( 7.67 s ) optical pulsations in all five bands .
the optical pulsations , which are at the same frequency as the x - ray pulsations caused by rotation of the highly - magnetized accreting neutron star primary , are understood as reprocessing of the pulsed x - ray emission in the accretion disk or on the surface of the secondary .
the optical pulsed fraction is roughly 6% , independent of wavelength , indicating that the optical emission is dominated by x - ray reprocessing .
a weaker ( 1.5% ) sideband , downshifted 0.395(15 ) mhz from the main optical pulsation , is also present .
this is consistent with a previously reported sideband which was downshifted 0.4011(21 ) mhz from the main pulsation , corroborating the 42-min binary period proposed by middleditch et al .
( 1981 , apj , 244 , 1001 ) . a 0.048 hz optical quasi - periodic oscillation ( qpo ) , corresponding to a previously reported x - ray feature ,
was also detected in some of the observations , with a fractional rms amplitude of 35% .
this is the first measurement of an optical qpo in an x - ray binary pulsar .
i discuss constraints on the nature of the mass donor and show that mass transfer via a radiatively - driven wind is inconsistent with the optical data .
i also review the basic theory of x - ray - heated accretion disks and show that such models provide a good fit to the optical photometry .
if the effective x - ray albedo of lmxb accretion disks is as high as recently reported ( @xmath0 ) , then the optical data imply a distance of @xmath18 kpc and an x - ray luminosity of @xmath2 erg s@xmath3 .
submitted june 1 , 1997 to the astrophysical journal .
And you have already written the first three sentences of the full article: the optical emission from low mass x - ray binaries ( lmxbs ) is generally dominated by the reprocessing of x - rays in the accretion disk and/or the mass donor ( see van paradijs & mcclintock 1995 for a review ) .
the time history of the optical emission is thus a convolution of the x - ray intensity history with a function representing the spatial distribution of matter in the system .
the most spectacular examples of this phenomenon are the optical novae accompanying soft x - ray transients , which can cause the optical counterpart to brighten by many magnitudes . of greater interest.
Please generate the next two sentences of the article | are those systems whose x - ray intensity histories are more regularly or sharply modulated .
many lmxbs show periodic optical variability due to orbitally - modulated viewing of the x - ray heated mass donor , providing constraints on the binary inclination and the distribution of reprocessing material in the system ( see van paradijs & mcclintock 1995 and references therein ) . |
8,888 | Suppose that you have an abstract for a scientific paper: in a _ closed @xmath0-cell embedding _ of a graph each face is homeomorphic to an open disk and is bounded by a cycle in the graph .
the orientable strong embedding conjecture says that every @xmath0-connected graph has a closed @xmath0-cell embedding in some orientable surface .
this implies both the cycle double cover conjecture and the strong embedding conjecture . in this paper
we prove that every @xmath0-connected projective - planar cubic graph has a closed @xmath0-cell embedding in some orientable surface .
the three main ingredients of the proof are ( 1 ) a surgical method to convert nonorientable embeddings into orientable embeddings ; ( 2 ) a reduction for @xmath1-cycles for orientable closed @xmath0-cell embeddings , or orientable cycle double covers , of cubic graphs ; and ( 3 ) a structural result for projective - planar embeddings of cubic graphs .
we deduce that every @xmath0-edge - connected projective - planar graph ( not necessarily cubic ) has an orientable cycle double cover .
epsf.sty amssym.def .
And you have already written the first three sentences of the full article: in this paper all graphs are finite and may have multiple edges but no loops .
a graph is _ simple _ if it has no multiple edges .
pseudograph _ may have multiple edges and loops . by a _ surface _.
Please generate the next two sentences of the article | we mean a connected compact @xmath0-manifold without boundary .
the nonorientable surface of genus @xmath2 is denoted @xmath3 . by an _ |
8,889 | Suppose that you have an abstract for a scientific paper: solar prominences are an important tool for studying the structure and evolution of the coronal magnetic field . here
we consider so - called `` hedgerow '' prominences , which consist of thin vertical threads .
we explore the possibility that such prominences are supported by tangled magnetic fields .
a variety of different approaches are used .
first , the dynamics of plasma within a tangled field is considered .
we find that the contorted shape of the flux tubes significantly reduces the flow velocity compared to the supersonic free fall that would occur in a straight vertical tube .
second , linear force - free models of tangled fields are developed , and the elastic response of such fields to gravitational forces is considered . we demonstrate that the prominence plasma can be supported by the magnetic pressure of a tangled field that pervades not only the observed dense threads but also their local surroundings .
tangled fields with field strengths of about 10 g are able to support prominence threads with observed hydrogen density of the order of @xmath0 @xmath1 . finally , we suggest that the observed vertical threads are the result of rayleigh - taylor instability
. simulations of the density distribution within a prominence thread indicate that the peak density is much larger than the average density .
we conclude that tangled fields provide a viable mechanism for magnetic support of hedgerow prominences . .
And you have already written the first three sentences of the full article: solar prominences ( a.k.a . filaments ) are relatively cool structures embedded in the million - degree corona at heights well above the chromosphere . above the solar limb , prominences appear as bright structures against the dark background , but when viewed as filaments on the solar disk they can be brighter or darker than their surroundings , depending on the bandpass used to observe them .
magnetic fields are thought to play an important role in supporting the prominence plasma against gravity , and in insulating it from the surrounding hot corona .
most quiescent prominences exhibit intricate filamentary structures that evolve continually due to plasma flows and heating / cooling processes . in some cases the threads appear to be mostly horizontal , while in other cases they are clearly radially oriented ( `` hedgerow '' prominences ) ..
Please generate the next two sentences of the article | figure [ fig : proms ] shows several examples of prominences observed in h@xmath2 at the big bear solar observatory ( bbso ) and the dutch open telescope ( dot ) .
the examples in figs . [ |
8,890 | Suppose that you have an abstract for a scientific paper: we study the octonionic selfduality equations for @xmath0-branes in the light cone gauge and we construct explicitly , instanton solutions for spherical and toroidal topologies in various flat spacetime dimensions @xmath1 , extending previous results for @xmath2 membranes . assuming factorization of time we reduce the self - duality equations to integrable systems and we determine explicitly periodic , in euclidean time , solutions in terms of the elliptic functions .
these solutions describe 4d associative and non - associative calibrations in @xmath3 dimensions .
it turns out that for spherical topology the calibration is non compact while for the toroidal topology is compact .
we discuss possible applications of our results to the problem of 3-brane topology change and its implications for a non - perturbative definition of the 3-brane interactions .
cern - th-2017 - 045 + + emmanuel floratos @xmath4 and george k. leontaris@xmath5 + @xmath6 _ institute of nuclear physics , nrcs demokritos , _ _
athens , greece _
@xmath7 _ department of physics , university of athens , _ _ athens , greece _
@xmath8 _ theory department , cern , _ _
ch-1211 , geneva 23 , switzerland _
@xmath9 _ physics department , theory division , ioannina university , _ _ gr-45110 ioannina , greece _ .
And you have already written the first three sentences of the full article: the tremendous progress of understanding of perturbative superstring theory as well as its duality symmetries in various spacetime backgrounds @xcite has led to a well substantiated proposal of m theory , the unifying theory of all superstring theories @xcite-@xcite .
the new objects contained in m - theory which are solitonic gravitational back - reactions of various d - branes , are the m2 and m5-branes .
these objects were expected naturally from the eleven dimensional ( 11d ) supergravity and , in this framework , they are considered as fundamental as the strings are for the various 10d supergravities ..
Please generate the next two sentences of the article | the basic obstacle in understanding these objects as fundamentals , lies in the absence of a coupling constant and the consequent problem of the definition of their self - interactions .
an interesting proposal to define the self - interactions of the branes is to use their euclidean instantons to interpolate between vacua ( asymptotic states ) with different number of branes @xcite . |
8,891 | Suppose that you have an abstract for a scientific paper: theoretical considerations and observational data support the idea that mergers were more frequent in the past . at redshifts
@xmath0 to @xmath1 , violent interactions and mergers may be implicated by observations of lyman - break galaxies , sub - mm starbursts , and active galactic nuclei .
most stars in cluster ellipticals probably formed at such redshifts , as did most of the halo and globular clusters of the milky way ; these events may all be connected with mergers .
but what _ kind _ of galaxies merged at high redshifts , and are present - epoch mergers useful guides to these early collisions ?
i will approach these questions by describing ideas for the formation of the milky way , elliptical galaxies , and systems of globular clusters . .
And you have already written the first three sentences of the full article: why is it so plausible that galactic mergers and tidal interactions were more frequent in the past ?
several theoretical reasons come to mind : * hierarchical clustering , in which small objects are progressively incorporated into larger structures @xcite , is common to many accounts of galaxy formation . in the `` core - halo '' picture @xcite , clustering of dark matter creates galaxy halos which subsequently accumulate cores of baryons , forming visible galaxies . *
tidal encounters generate short - lived features ; a population of binary galaxies with highly eccentric orbits is required to explain the peculiar galaxies observed today @xcite . if these binaries have a flat distribution of binding energies , their merger rate has declined with time as @xmath2 , and the @xmath3 or so merging galaxies in the ngc catalog are but the most recent additions to a population of about @xmath4 remnants @xcite . * the cdm model @xcite provides a concrete example of galaxy formation in which merging of dark halos is easily calculated and clearly important @xcite ..
Please generate the next two sentences of the article | observations , though not always reaching the redshift range emphasized in this meeting , also imply rapid merging at high redshift : * various counting strategies indicate that the pair density grows like @xmath5 , where @xmath6 @xcite . *
peculiar morphology becomes more common with increasing redshift @xcite . |
8,892 | Suppose that you have an abstract for a scientific paper: we present a detailed study of the decays of the higgs bosons @xmath0 , @xmath1 , and @xmath2 within the minimal supersymmetric standard model including susy qcd corrections .
we find that the supersymmetric modes @xmath3 ( @xmath4 , and for large @xmath5 @xmath6 ) can dominate the @xmath0 ( @xmath1 , @xmath2 ) decays in a wide range of the model parameters due to the large yukawa couplings and mixings of @xmath7 and @xmath8 .
compared to the conventional modes @xmath9 , and @xmath10 , the supersymmetric modes can have an important impact on the higgs boson searches at future colliders .
= -1 cm = 13.9 cm 0.0 in 0.0 in _ _
hep - ph/9709253 * higgs particle decays in supersymmetry * + .
And you have already written the first three sentences of the full article: the minimal supersymmetric standard model ( mssm ) @xcite implies the existence of five physical higgs bosons @xmath11 ,
@xmath1 , @xmath2 , and @xmath12 @xcite . for the search of these particles a precise knowledge of all possible decay modes
is necessary ..
Please generate the next two sentences of the article | the higgs boson decays to supersymmetric ( susy ) particles could be very important if they are kinematically allowed .
this can be the case for the charged higgs boson @xmath0 , and the neutral higgs bosons @xmath1 and @xmath2 . |
8,893 | Suppose that you have an abstract for a scientific paper: we study the formation of low - mass and extremely metal - poor stars in the early universe .
our study is motivated by the recent discovery of a low - mass ( @xmath0 ) and extremely metal - poor ( @xmath1 ) star in the galactic halo by @xcite .
we propose a model that early supernova ( sn ) explosions trigger the formation of low - mass stars via shell fragmentation .
we first perform one - dimensional hydrodynamic simulations of the evolution of an early sn remnant .
we show that the shocked shell undergoes efficient radiative cooling and then becomes gravitationally unstable to fragment and collapse in about a million years .
we then follow the thermal evolution of the collapsing fragments using a one - zone code .
our one - zone calculation treats chemistry and radiative cooling self - consistently in low - metallicity gas .
the collapsing gas cloud evolves roughly isothermally , until it cools rapidly by dust continuum emission at the density @xmath2@xmath3 .
the cloud core then becomes unstable and fragments again .
we argue that early sne can trigger the formation of low - mass stars in the extremely metal - poor environment as @xcite discovered recently . .
And you have already written the first three sentences of the full article: stars with masses @xmath4 formed in the early universe may survive to the present day .
such old low - mass stars should typically have very low metallicites because they were formed from a gas that had not been significantly enriched with heavy elements .
they carry invaluable information on the early chemical evolution of the galaxy @xcite ..
Please generate the next two sentences of the article | recently , @xcite discovered a low - mass and extremely metal - deficient star in the halo of the galaxy .
the star has extremely small abundances of carbon and nitrogen . |
8,894 | Suppose that you have an abstract for a scientific paper: we devise a phase - coherent three - pulse protocol to probe the polariton dynamics in a trapped - ion quantum simulation .
in contrast to conventional nonlinear signals , the presented scheme does not change the number of excitations in the system , allowing for the investigation of the dynamics within an @xmath0-excitation manifold . in the particular case of a filling factor one ( @xmath0 excitations in an @xmath0-ion chain ) ,
the proposed interaction induces coherent transitions between a delocalized phonon superfluid and a localized atomic insulator phase .
numerical simulations of a two - ion chain demonstrate that the resulting two - dimensional spectra allow for the unambiguous identification of the distinct phases , and the two - dimensional lineshapes efficiently characterize the relevant decoherence mechanism . .
And you have already written the first three sentences of the full article: polaritons - hybrid quasiparticles originating from the strong coupling between light modes and matter excitations - represent an important research area , both for fundamental and practical reasons : their bosonic character may lead to bose - einstein condensation @xcite , and the larger coherence length of the light modes may enhance the carrier mobility in organic semiconductors @xcite . while originating primarily in quantum - optical settings such as josephson junctions and arrays of coupled cavities @xcite , polaritonic excitations are now also studied in molecular systems @xcite .
alternatively , trapped ions can be used to study the properties of strongly correlated systems under well - controlled conditions and with manageable , slower time scales than solid - state systems @xcite .
polaritonic systems can be modeled in ion trap experiments by coupling the electronic and vibrational degrees of freedom of the ions confined by a harmonic potential ..
Please generate the next two sentences of the article | the atomic excitations are encoded into the ions electronic states , and the local vibrational modes of the ions , described by quantum mechanical harmonic oscillators , take on the role of the light modes .
the coulomb repulsion between the ions leads to couplings of the local phonons . |
8,895 | Suppose that you have an abstract for a scientific paper: we investigate the effects of a charge asymmetry on the spectrum of dileptons radiating from a quark gluon plasma .
we demonstrate the existence of a new set of processes in this regime . the dilepton production rate from the corresponding diagrams is shown to be as important as that obtained from the born - term quark - antiquark annihilation .
address = department of physics , mcgill university , montreal , qc , canada h3a 2t8 , [email protected] , address = department of physics , mcgill university , montreal , qc , canada h3a 2t8 , [email protected] , .
And you have already written the first three sentences of the full article: the aim of this talk is to show that , when in a medium there is a finite charge density ( i.e. , a finite chemical potential ) , a new set of lepton pair - producing processes actually arises .
we then calculate a new contribution to the 3-loop photon self - energy .
the various cuts of this self - energy contain higher loop contributions to the usual processes of @xmath0 , @xmath1 , @xmath2 , and an entirely new channel : @xmath3 ..
Please generate the next two sentences of the article | we calculate the contribution of this new reaction to the differential production rate of back - to - back dileptons .
it is finally shown that , within reasonable values of parameters , this process may become larger than the differential rate from the bare tree level @xmath0 . at zero temperature , and at finite temperature and zero charge density ( note : |
8,896 | Suppose that you have an abstract for a scientific paper: we report the first measurement of the diffusion coefficients of francium and rubidium ions implanted in a yttrium foil .
we developed a methodology , based on laser spectroscopy , which can be applied to radioactive and stable species , and allows us to directly take record of the diffusion time .
+ francium isotopes are produced via fusion - evaporation nuclear reaction of a 100 mev @xmath0o beam on a au target at the tandem xtu accelerator facility in legnaro , italy .
francium is ionized at the gold - vacuum interface and fr@xmath1 ions are then transported with a 3 kev electrostatic beamline to a cell for neutralization and capture in a magneto - optical trap ( mot ) .
a rb@xmath1 beam is also available , which follows the same path as fr@xmath1 ions .
the accelerated ions are focused and implanted in a 25 @xmath2 m thick yttrium foil for neutralization : after diffusion to the surface , they are released as neutrals , since the y work function is lower than the alkali ionization energies .
the time evolution of the mot and the vapor fluorescence signals are used to determine diffusion times of fr and rb in y as a function of temperature . .
And you have already written the first three sentences of the full article: in many experiments with radioactive atoms , elements are produced as ions and then neutralized .
the most important requirement for a neutralization system is the fast release of neutral atoms , with respect to their radioactive decay time . in particular , in our francium experiment at infn s national laboratories in legnaro , italy @xcite , we produce fr ions that have to be neutralized before accumulation in a magneto - optical trap .
the system must be very efficient , as a large sample of fr atoms is requested for nuclear decay , atomic parity violation and permanent electric dipole studies ..
Please generate the next two sentences of the article | our apparatus follows the scheme of the stony brook experiment @xcite , where many measurements on fr have been performed so far .
francium isotopes are produced at the tandem accelerator facility in legnaro via the fusion - evaporation reaction @xmath3 with an energy of the primary beam around 100 mev , we are able to produce fr isotopes in the mass number range 208 - 211 . |
8,897 | Suppose that you have an abstract for a scientific paper: we discuss the differences between two well - studied and related phenomena
coherent population trapping ( cpt ) and electromagnetically induced transparency ( eit ) .
many differences between the two such as the effect of power in the beams , detuning of the beams from resonance , and the use of vapor cells filled with buffer gas are demonstrated experimentally .
the experiments are done using magnetic sublevels of the @xmath0 transition in the d@xmath1 line of @xmath2rb . + * keywords * : electromagnetically induced transparency ; coherent population trapping ; coherent control ; quantum optics . .
And you have already written the first three sentences of the full article: the phenomenon of coherent population trapping ( cpt ) , reviewed by arimondo in ref .
@xcite , and the phenomenon of electromagnetically induced transparency ( eit ) , reviewed in refs .
@xcite and @xcite , are two sides of the same coin ..
Please generate the next two sentences of the article | both phenomena have been studied for a long time in three - level systems cpt in lambda type ; and eit in all the three kinds namely lambda type , ladder type , and vee type .
the physics underlying the two phenomena are related , but are also distinct in many ways . |
8,898 | Suppose that you have an abstract for a scientific paper: the renyi , shannon and fisher spreading lengths of the classical or hypergeometric orthogonal polynomials , which are quantifiers of their distribution all over the orthogonality interval , are defined and investigated .
these information - theoretic measures of the associated rakhmanov probability density , which are direct measures of the polynomial spreading in the sense of having the same units as the variable , share interesting properties : invariance under translations and reflections , linear scaling and vanishing in the limit that the variable tends towards a given definite value .
the expressions of the renyi and fisher lengths for the hermite polynomials are computed in terms of the polynomial degree .
the combinatorial multivariable bell polynomials , which are shown to characterize the finite power of an arbitrary polynomial , play a relevant role for the computation of these information - theoretic lengths .
indeed these polynomials allow us to design an error - free computing approach for the entropic moments ( weighted @xmath0-norms ) of hermite polynomials and subsequently for the renyi and tsallis entropies , as well as for the renyi spreading lengths .
sharp bounds for the shannon length of these polynomials are also given by means of an information - theoretic - based optimization procedure .
moreover , it is computationally proved the existence of a linear correlation between the shannon length ( as well as the second - order renyi length ) and the standard deviation . finally , the application to the most popular quantum - mechanical prototype system , the harmonic oscillator , is discussed and some relevant asymptotical open issues related to the entropic moments mentioned previously are posed .
orthogonal polynomials , hermite polynomials , spreading lengths , computation of information measures , shannon entropy , renyi entropy , fisher information , bell polynomials .
89.70.cf 33c45 , 94a17 , 62b10 , 65c60 .
And you have already written the first three sentences of the full article: let @xmath1 denote a sequence of real orthonormal polynomials with respect to the weight function @xmath2 on the interval @xmath3 ( see e.g. @xcite ) , i.e. @xmath4 the distribution of these polynomials along the orthogonality interval can be complementarily measured by means of the spreading properties of the normalized - to - unity density function @xmath5=p_n^2 ( x ) \omega(x ) , \label{eq : rakhmanov_density}\ ] ] which is called rakhmanov s density of the polynomial @xmath6 , to honor the pioneering work @xcite of this mathematician who has shown that this density governs the asymptotic @xmath7 behaviour of the ratio @xmath8 .
physically , this probability density characterizes the stationary states of a large class of quantum - mechanical potentials @xcite . beyond the variance ,
the spreading of the orthogonal polynomials is best analyzed by the information - theoretic properties of their associated rakhmanov probability densities ; namely , the fisher information @xcite , the renyi entropy @xcite and the shannon entropy @xcite ..
Please generate the next two sentences of the article | the information - theoretic knowledge of the orthogonal polynomials up to 2001 is reviewed in ref @xcite , where the quantum - mechanical motivation and some physical applications are also given , and up today in @xcite , where emphasis is made on asymptotics .
therein , it is pointed out that the study of the information - theoretic measures of orthogonal polynomials was initiated in the nineties with the asymptotic computation of the renyi and shannon entropies of the classical orthogonal polynomials @xcite . up until now , however , the explicit expressions of these two spreading measures are not known save for the shannon measure for some particular subclasses of the jacobi polynomials ; namely the chebyshev polynomials of first and second type @xcite and the gegenbauer polynomials @xmath9 with integer parameter @xmath10 @xcite . on the other hand , |
8,899 | Suppose that you have an abstract for a scientific paper: the measure of the third - order structure function , @xmath0 , is employed in the solar wind to compute the cascade rate of turbulence . in the absence of a mean field @xmath1
, @xmath0 is expected to be isotropic ( radial ) and independent of the direction of increments , so its measure yields directly the cascade rate . for turbulence with mean field , as in the solar wind , @xmath0 is expected to become more two dimensional ( 2d ) , that is , to have larger perpendicular components , losing the above simple symmetry . to get the cascade rate one should compute the flux of @xmath0 , which is not feasible with single - spacecraft data , thus measurements rely on assumptions about the unknown symmetry .
we use direct numerical simulations ( dns ) of magneto - hydrodynamic ( mhd ) turbulence to characterize the anisotropy of @xmath0 .
we find that for strong guide field @xmath2 the degree of two - dimensionalization depends on the relative importance of shear and pseudo polarizations ( the two components of an alfvn mode in incompressible mhd ) .
the anisotropy also shows up in the inertial range .
the more @xmath0 is 2d , the more the inertial range extent differs along parallel and perpendicular directions .
we finally test the two methods employed in observations and find that the so - obtained cascade rate may depend on the angle between @xmath3 and the direction of increments . both methods
yield a vanishing cascade rate along the parallel direction , contrary to observations , suggesting a weaker anisotropy of solar wind turbulence compared to our dns
. this could be due to a weaker mean field and/or to solar wind expansion . .
And you have already written the first three sentences of the full article: magneto - hydrodynamic ( mhd ) turbulence in the presence of a mean - field @xmath3 has a tendency to become two - dimensional ( 2d ) .
this tendency was early recognized by inspection of the fourier energy spectra in direct numerical simulations ( dns ) .
the energy distribution is indeed anisotropic , residing in wavevector mostly perpendicular to the mean magnetic field @xcite ..
Please generate the next two sentences of the article | ideally one would like to quantify the two - dimensionalization as a scaling relation between parallel and perpendicular wavenumbers having the same energy density , @xmath4 .
if @xmath5 the anisotropy is scale independent , and the aspect ratio @xmath6 of the isocontour of the fourier spectrum does not change with scales . |
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