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7,100 | Suppose that you have an abstract for a scientific paper: we discuss the generation of primordial magnetic fields during inflation in the dilaton - axion electromagnetism , in which the dilaton and axion dynamics are introduced in terms of two time dependent functions of the cosmic scale factor , @xmath0 and @xmath1 , respectively , where @xmath2 is the electromagnetic field strength and @xmath3 is its dual .
we study the form of @xmath4 that can generate a large seed magnetic field .
although the @xmath4 function is model dependent , the axion - photon coupling may open up a new window for a successful inflationary magnetogenesis . .
And you have already written the first three sentences of the full article: presently the origin still remains elusive for the observed galactic and extragalactic magnetic fields of about a few @xmath5 g @xcite .
it is generally believed that the so - called galactic dynamo @xcite mechanism must be involved to amplify a magnetic seed field @xmath6 g on a comoving scale larger than mpc .
since the universe is in a highly conducting plasma state through the most of its history , the ratio of the magnetic energy density and the thermal background , @xmath7 , remains constant along the cosmic evolution ..
Please generate the next two sentences of the article | the required @xmath8 is then translated into @xmath9 .
depending on the correlation scale of the magnetic field , the seed fields can be produced inside or outside the hubble sphere . |
7,101 | Suppose that you have an abstract for a scientific paper: using an effective strongly coupled lattice qcd hamiltonian and wilson fermions we calculate the equation of state for cold and dense quark matter by constructing an ansatz which exactly diagonalizes the hamiltonian to second order in field operators for all densities .
this ansatz obeys the free lattice dirac equation with a chemical potential term and a mass term which is interpreted as the dynamical quark mass .
we find that the order of chiral phase transition depends on the values of input parameters . in the phase with spontaneously broken chiral symmetry the quark fermi sea has negative pressure indicating its mechanical instability .
this result is in qualitative agreement with those obtained using continuum field theory models with four point interactions . .
And you have already written the first three sentences of the full article: simulating finite density qcd is one of the outstanding problems in lattice gauge theory @xcite . because of the sign problem
no reliable numerical simulations of finite density qcd with three colors exist even in the strong coupling limit @xcite .
this is a rather frustrating situation in view of the current intense interest in finite density qcd fueled by the phenomenology of heavy ion collisions , neutron stars , early universe and color superconductivity ..
Please generate the next two sentences of the article | therefore even a qualitative description of strongly coupled qcd at finite density using field theoretical methods is quite welcome .
strongly coupled qcd at finite quark chemical potential @xmath0 has previously been studied analytically both in the euclidean @xcite and in the hamiltonian @xcite formulations . except for @xcite , |
7,102 | Suppose that you have an abstract for a scientific paper: almost all galactic black hole binaries with low mass donor stars are transient x - ray sources ; we expect most of the x - ray transients observed in external galaxies to be black hole binaries also . obtaining period estimates for extra - galactic transients is challenging , but the resulting period distribution is an important tool for modeling the evolution history of the host galaxy . we have obtained periods , or upper limits , for 12 transients in m31 , using an updated relation between the optical and x - ray luminosities . we have monitored the central region of m31 with chandra for the last @xmath012 years , and followed up promising transients with hst ; 4@xmath1 b magnitude limits for optical counterparts are 2629 , depending on crowding .
we obtain period estimates for each transient for both neutron star and black hole accretors .
periods range from @xmath20.4 to 490@xmath390 hours ( @xmath20.97 to @xmath2175 hrs if all are bh systems ) .
these m31 transients appear to be somewhat skewed towards shorter periods than the milky way ( mw ) transients ; indeed , comparing the m31 and mw transients with survival analysis techniques used to account for some data with only upper limits yield probabilities of @xmath00.020.08 that the two populations are drawn from the same distribution .
we also checked for a correlation between orbital period and distance from the nucleus , finding a 12% probability of no correlation .
further observations of m31 transients will strengthen these results . .
And you have already written the first three sentences of the full article: x - ray binaries ( xbs ) represent the end - points of stellar evolution , and the xb population of a galaxy is informed by the star formation history of that galaxy .
one way of characterizing such populations is the distribution of their orbital periods ; however , the estimation orbital periods for extra - galactic xbs is extremely challenging , unless they happen to be at high enough inclinations to exhibit dips and/or eclipses .
the most accessible extra - galactic population for period studies is the m31 x - ray transient group ..
Please generate the next two sentences of the article | these are expected to be low mass x - ray binaries ( lmxbs ) with black hole ( bh ) primaries , since the galactic bh lmxbs are nearly all transient @xcite ; transient neutron star lmxbs also exist , but the majority of transients contain bh primaries ( see e.g. * ? ? ? * ) .
x - ray and optical observations of these transients allow us to estimate their size , and therefore period , using the methods described below . |
7,103 | Suppose that you have an abstract for a scientific paper: coherence vortices are screw - type topological defects in the phase of glauber s two - point degree of quantum coherence , associated with pairs of spatial points at which an ensemble - averaged stochastic quantum field is uncorrelated .
coherence vortices may be present in systems whose dimensionality is too low to support spatial vortices .
we exhibit lattices of such quantum - coherence phase defects for a one - dimensional model quantum system .
we discuss the physical meaning of coherence vortices and propose how they may be realized experimentally . .
And you have already written the first three sentences of the full article: vortices have fascinated the minds of scientists throughout history . beginning with the angular momentum eigenstates of the hydrogen atom , quantum - mechanical vortices emerged as key entities characterizing quantum liquids such as superconductors and superfluid helium @xcite .
more recently , quantized vortices have been observed e.g. in bose - einstein condensates @xcite , quantum degenerate fermi gases @xcite , and in coherent optical @xcite and acoustic fields @xcite .
quantized vortices , known as coherence vortices , have since been discovered in the cross - spectral density and related coherence functions of partially - coherent classical - optical fields @xcite . here.
Please generate the next two sentences of the article | we show that coherence vortices , which are screw - type singular phase defects in glauber s second order degree of quantum coherence , may exist even in systems with only one spatial dimension where orbital angular momentum and conventional quantized vortices can not be defined .
we exhibit a one - dimensional model system in which decoherence @xcite is accompanied by a proliferation of quantized phase vortices in the coherence function associated with the resulting statistical mixture . in a space of such low dimensionality , |
7,104 | Suppose that you have an abstract for a scientific paper: the mira ab system is a nearby ( @xmath0107pc ) example of a wind accreting binary star system . in this class of system
, the wind from a mass - losing red giant star ( mira a ) is accreted onto a companion ( mira b ) , as indicated by an accretion shock signature in spectra at ultraviolet and x - ray wavelengths . using novel imaging techniques , we report the detection of emission at mid - infrared wavelengths between 9.7 and 18.3@xmath1 m from the vicinity of mira b but with a peak at a radial position about 10 au closer to the primary mira a. we interpret the mid - infrared emission as the edge of an optically - thick accretion disk heated by mira a. the discovery of this new class of accretion disk fed by m - giant mass loss implies a potential population of young planetary systems in white - dwarf binaries which has been little explored , despite being relatively common in the solar neighborhood . .
And you have already written the first three sentences of the full article: mira ( o ceti ) is the prototype of the class of mira - type variable stars , characterized observationally by large visual photometric pulsation amplitudes and regular periods between 100 and 1000 days .
mira - type variables represent one of the late stages of evolution for 1 - 2 solar mass stars , with luminosities of several thousand times solar and mass loss rates of order @xmath2 solar masses per year .
the winds from mira - type variables are relatively slow ( typically @xmath310 kms@xmath4 ) , which means that the mass lost in these winds can be readily accreted onto any stellar companions ..
Please generate the next two sentences of the article | it is known that 57% of the progenitors of mira - type variables , g and f dwarfs , have a companion with a mass more than a tenth of the primary mass @xcite .
however , most of the companions around mira - type primaries remain undetected because of the overwhelming flux of the mira - type primary and the difficulty in making precise radial velocity measurements due to the stellar pulsation . |
7,105 | Suppose that you have an abstract for a scientific paper: recently nelson _ et al . _ proposed an interesting flavor symmetric model to account for the top quark forward - backward asymmetry and the dijet anomaly at cdf simultaneously with just three parameters : a coupling constant of order one , and two scalar masses of 160 gev and 220 gev .
however these fiducial values of the parameters lead to the branching ratio of a almost pure penguin @xmath0 decay about one hundred times larger than the experimental results .
consider also the precision electroweak constraints , the scalar masses should be at least around 500 gev . actually with the coupling constant larger than one , it is impossible to explain either of the two cdf measurements consistently in this model .
but one may raise the charged scalar mass to , for example , @xmath1 gev and reduce the coupling strength to @xmath2 to meet the b physics constraints . with this parameter set
, the wjj cross section is found to be in the right range .
but due to the scalar mass splitting , its correction to t - parameter is about @xmath3 away from the precision electroweak constraints .
in addition , the top quark forward - backward asymmetry should be well below @xmath4 with this small coupling constant .
the cdf collaboration has recently updated the measurements on the forward - backward asymmetry in top quark pair production with a larger data sample about @xmath5 fb@xmath6@xcite .
interestingly , deviations from the standard model ( sm ) predictions are observed in the total forward - backward asymmetry both in the semi - leptonic @xmath7 data and in the di - lepton channel .
in addition , a distributional measurement found that @xmath8 in the @xmath9 rest frame , which deviates from the qcd correction prediction @xmath10 by @xmath11 .
the cdf collaboration has also reported another @xmath12 anomaly in the @xmath13 gev range of the invariant dijet mass distribution in association with a w boson @xcite .
a flavor symmetric model was proposed in @xcite to explain simultaneously the....
And you have already written the first three sentences of the full article: this work is supported in part by the national science foundation of china ( no . 11075139 and no.10705024 ) .
g.z is also supported in part by the fundamental research funds for the central universities .
t. aaltonen _ et al . _.
Please generate the next two sentences of the article | [ cdf collaboration ] , [ arxiv:1104.0699 [ hep - ex ] ] .
a. e. nelson , t. okui and t. s. roy , [ arxiv:1104.2030 [ hep - ph ] ] |
7,106 | Suppose that you have an abstract for a scientific paper: we prove that if @xmath0 is a non - uniform lattice in a rank - one semi - simple lie group @xmath1 then @xmath0 is quasi - isometrically co - hopf .
this means that every quasi - isometric embedding @xmath2 is coarsely surjective and thus is a quasi - isometry .
[ multiblock footnote omitted ] .
And you have already written the first three sentences of the full article: the notion of co - hopficity plays an important role in group theory . recall that a group @xmath0 is said to be _ co - hopf _
if @xmath0 is not isomorphic to a proper subgroup of itself , that is , if every injective homomorphism @xmath2 is surjective .
a group @xmath0 is _ almost co - hopf _ if for every injective homomorphism @xmath3 we have @xmath4<\infty$ ] . clearly , being co - hopf implies being almost co - hopf ..
Please generate the next two sentences of the article | the converse is not true : for example , for any @xmath5 the free abelian group @xmath6 is almost co - hopf but not co - hopf .
it is easy to see that any freely decomposable group is not co - hopf . in particular , |
7,107 | Suppose that you have an abstract for a scientific paper: the present paper is part of a broader programme , exploring the possibility of involving the microsoft kinect@xmath0 sensor in the analysis of human motion . in this study ,
the output obtained from the two available versions of this sensor is critically examined .
we demonstrate that the two outputs differ in regard to the variation of the physical quantities involved in the modelling of the human motion .
as the original sensor has been found unsuitable for applications requiring high precision , the observed differences in the output of the two sensors call for the validation of the upgraded sensor on the basis of a marker - based system .
+ _ pacs : _ 87.85.gj ; 07.07.df , biomechanics , motion analysis ,
treadmill , kinect @xmath1e - mail : evangelos[dot]matsinos[at]zhaw[dot]ch , evangelos[dot]matsinos[at]sunrise[dot]ch .
And you have already written the first three sentences of the full article: microsoft kinect@xmath0 ( hereafter , simply ` kinect ' ) @xcite , a low - cost , portable motion - sensing hardware device , was developed by the microsoft corporation ( microsoft , usa ) as an accessory to the xbox @xmath2 video - game console ( 2010 ) .
the sensor is a webcamera - type , add - on peripheral device , enabling the operation of xbox via gestures and spoken commands . in 2011 , microsoft released the software - development kit ( sdk ) for kinect , thus enabling the development of applications in several standard programming languages .
the first upgrade of the sensor ( ` kinect for windows v2 ' ) , both hardware- and software - wise , tailored to the needs of xbox one , became available ( in july 2014 ) for general development and use ..
Please generate the next two sentences of the article | the present paper is part of our research programme , aiming at investigating the possibility of involving either of the kinect sensors in the analysis of motion data of subjects walking or running ` in place ' ( e.g. , on commercially - available treadmills ) .
if successful , kinect could become an interesting alternative to marker - based systems ( mbss ) in capturing data for motion analysis , one with an incontestably high benefit - to - cost ratio . |
7,108 | Suppose that you have an abstract for a scientific paper: a many body hamiltonian comprising pairing , quadrupole - quadrupole and spin - spin interaction is treated within a projected spherical basis with the aim of describing the detailed structure of the magnetic states of orbital and spin - flip nature in @xmath0sm . the mean field for the single particle motion takes care of the volume conservation of a phenomenological core which results in having a complex dependence on deformation for single particle energies .
several experimental features like the total orbital and total spin strengths , the shape of the orbital strength distribution , the hump structure of the spin strength distribution , the quadratic dependence of the orbital strength on nuclear deformation , the saturation effect of the orbital strength with respect to the casten s factor p are very well described within a quasiparticle random phase approximation formalism .
comparison of present results with those obtained in some previous treatments are also given .
# 1@xmath1#1 .
And you have already written the first three sentences of the full article: the collective magnetic dipole mode ( m1 ) was one of the central subjects in the last two decades .
the interest has grown with time due to the wealth of experimental data provided by several groups performing either @xmath2 experiments at backward angles with high resolution or @xmath3 measurements using brehmstralung radiation .
the theoretical work in this field preceded the experiment ..
Please generate the next two sentences of the article | indeed lo iudice and palumbo @xcite predicted the existence of this state from an anti - phase angular oscillation of proton and neutron axially symmetric and rigid systems .
the model is known under the name of two rotor model ( trm ) , and the predicted mode as scissors mode . |
7,109 | Suppose that you have an abstract for a scientific paper: based on the bardeen cooper schrieffer ( bcs ) theory of superconductivity , the coherent splitting of cooper pairs from a superconductor to two spatially separated quantum dots has been predicted to generate nonlocal pairs of entangled electrons . in order to test this hypothesis
, we propose a scheme to transfer the spin state of a split cooper pair onto the polarization state of a pair of optical photons .
we show that the produced photon pairs can be used to violate a bell inequality , unambiguously demonstrating the entanglement of the split cooper pairs . .
And you have already written the first three sentences of the full article: entanglement @xcite , i.e. , correlations between parts of a quantum system that defy any classical description , lies at the heart of quantum mechanics .
it is the basis for many applications of quantum information theory , such as quantum teleportation @xcite , quantum computing @xcite , quantum cryptography @xcite , and quantum metrology @xcite .
the first experimental demonstration of entanglement has been achieved by violating bell s inequality @xcite with polarization - entangled optical photon pairs generated during spontaneous parametric down - conversion in a nonlinear crystal @xcite . in many applications , it is desirable to have a source of entangled pairs of spatially separated particles ..
Please generate the next two sentences of the article | such pairs are called epr pairs in reference to the seminal work of einstein , podolsky and rosen on the completeness of quantum mechanics @xcite .
compared to quantum optical scenarios , the generation of _ electronic _ epr pairs is rather challenging . |
7,110 | Suppose that you have an abstract for a scientific paper: we have implemented non - collinear gga and a generalized bloch s theorem to simulate unconmensurate spiral arrangements of spins in a density functional theory code based on localized wave functions .
we have subsequently performed a thorough study of the different states of bulk iron .
we determine the minimal basis set required to obtain reliable orderings of ground and excited states .
we find that the most stable fcc phase is a spiral with an equilibrium lattice constant 3.56 . .
And you have already written the first three sentences of the full article: advances in experimental setups along the past two decades have allowed to grow in a controlled way , and characterize , tiny structures and devices , paving the way for the slow development of those fields of materials science now covered under the umbrella of nanoscience .
ever more powerful computers and canny algorithms have also allowed to simulate larger and larger clusters of atoms or molecules , filling partially the bridge between theory and experiments .
molecular dynamics packages based on density functional theory ( dft)@xcite represent a specially useful set of theoretical tools in the analysis of such materials and devices . among them , those which use basis sets ( bs ) of localized wave functions are particularly attractive since , one the one hand , can be easily adapted to work with order - n algorithms , and on the other , they can be written in a tight - binding language , which allows for easier analytical approaches ..
Please generate the next two sentences of the article | siesta is a simulation package which literally implements the tight - binding philosophy .
@xcite indeed , it uses norm - conserving pseudopotentials @xcite to integrate away core energy levels and very flexible bs made up of numerical atomic - like wave - functions to handle valence electrons . |
7,111 | Suppose that you have an abstract for a scientific paper: a diffusion - deposition model for glassy dynamics in compacting granular systems is treated by time scaling and by a method that provides the exact asymptotic ( long time ) behavior .
the results include vogel - fulcher dependence of rates on density , inverse logarithmic time decay of densities , exponential distribution of decay times and broadening of noise spectrum .
these are all in broad agreement with experiments .
the main characteristics result from a marginal rescaling in time of the control parameter ( density ) ; this is argued to be generic for glassy systems .
glassy dynamics occurs with similar characteristics in a remarkably diverse range of systems @xcite .
this letter attempts to give reasons for this similarity .
+ it begins by considering an idealized model of granular materials , which is perhaps the simplest class of real systems showing glassy behavior .
the model is treated by approximate scaling and then by asymptotically exact methods .
the behavior is similar to that found in simulations and in the chicago experiments @xcite on real granular systems . because we expect diverging characteristic times ( while no diverging length has yet been seen in glassy systems ) the scaling procedure rescales time , @xmath0 . the consequent scaling equation for the control parameter , in this case the density @xmath1 , has a particular ( marginal ) form .
we show at the end of the letter that this leads directly to the best known characteristic features of glassy dynamics .
we also argue at the end that this marginal form arises when are excessively sensitive to changes of the control parameter , as is the case in glassy dynamics in general , so arriving at a universal scaling scenario .
+ all the following characteristics of glassy behavior @xcite are shared by super cooled molecular glass - forming liquids , structural glasses , foams , colloids and even ( shaken ) granular systems : @xmath2 extreme slowing of rates with typically a vogel - fulcher dependence on....
And you have already written the first three sentences of the full article: this work was supported by epsrc under the oxford condensed matter theory grant gr / m04426 .
the ideas developed initially at an itp ( santa barbara ) workshop in 1997 , and rbs would like to thank the participants , and particularly the directors s. nagel , a. liu and s. edwards , for sharing their insights .
see for example : _ jamming and rheology _ , edited by a. j. liu and s. r. nagel ( taylor & francis , london , 2001 ) , and overviews therein by d. levine ; d. j. durian and a. j. liu ; and j. kurchan . h. m. jaeger , c. h. liu and s. r. nagel , , 40 ( 1989 ) j. b. knight , h. m. jaeger and s. r. nagel , , 3728 ( 1993 ) j. b. knight , c. g. fandrich , c. n. lau , h. m. jaeger and s. r. nagel , , 3957 ( 1995 ) e. r. nowak , j. b. knight , e. ben - naim , h. m. jaeger and s. r. nagel , , 1971 ( 1998 ) e. ben - naim , j. b. knight and e. r. nowak , h. m. jaeger and s. r. nagel , physica d * 123 * , 380 ( 1998 ) c. a. angell and w. sichina , ann ..
Please generate the next two sentences of the article | * 279 * , 53 ( 1976 ) h. m. jaeger and s. r. nagel and r. p. behringer , , 1259 ( 1996 ) h. j. herrmann , in _ disorder and granular media _ , edited by d. bideau and a. hansen ( north - holland , amsterdam , 1993 ) , p.305 - 320 d. c. hong , s. yue , j. k. rudra , m. y. choi and y. w. kim , phys . rev .
e * 50 * , 4123 ( 1994 ) t. boutreux and p. g. de gennes , physica a * 224 * , 59 ( 1997 ) m. nicodemi , a. coniglio and h. j. herrmann , phys . |
7,112 | Suppose that you have an abstract for a scientific paper: we study the set of random matrix product states ( rmps ) introduced in pra * 81 * , 032336 as a tool to explore foundational aspects of quantum statistical mechanics . in the present work ,
we provide an accurate numerical and analytical investigation of the properties of rmps .
we calculate the average state of the ensemble in the non - homogeneous case , and numerically check the validity of this result .
we also suggest using rmps as a tool to approximate properties of general quantum random states .
the numerical simulations presented here support the accuracy and efficiency of this approximation .
these results suggest that any generalized canonical state can be approximated with high probability by the reduced density matrix of a random mps , if the average mps coincide with the associated microcanonical ensemble . .
And you have already written the first three sentences of the full article: the principle of equal a priori probabilities , which is at the foundation of statistical mechanics , postulates subjective ignorance at the core of our understanding of macroscopic systems .
it assumes that an isolated system is described by the microcanonical ensemble : an equal mixture over all possible microscopic configurations . on the other hand ,
quantum mechanics provides us with a powerful theory for understanding microscopic systems ..
Please generate the next two sentences of the article | it states that an isolated system is described by a pure state , which leaves no room for subjective ignorance . in the attempt to provide a consistent foundation of quantum statistical mechanics
a purely quantum mechanical explanation of the effectiveness of statistical ensembles has been debated for quite a long time . recently |
7,113 | Suppose that you have an abstract for a scientific paper: a family of random models for bosonic quasi - particle excitations , e.g. the vibrations of a disordered solid , is introduced .
the generator of the linearized phase space dynamics of these models is the sum of a deterministic and a random part .
the former may describe any model of @xmath0 identical phonon bands , while the latter is a @xmath1-dimensional generalization of the random matrix model of lueck , sommers , and zirnbauer ( lsz ) .
the models are constructed so as to exclude the unphysical occurrence of runaway solutions . by using the efetov - wegner supersymmetry method in combination with the new technique of superbosonization
, the disordered boson model is cast in the form of a supermatrix field theory .
a self - consistent approximation of mean - field type arises from treating the field theory as a variational problem .
the resulting scheme , referred to as a coherent potential approximation , becomes exact for large values of @xmath0 . in the random - matrix limit , agreement with the results of lsz is found .
the self - consistency equation for the full @xmath1-dimensional problem is solved numerically . .
And you have already written the first three sentences of the full article: small oscillations about the stable equilibrium of a many - body ground state are quantized as bosonic quasi - particles or bosons . in various physical contexts
the linearized equations of motion for such excitations are known as the random phase approximation , or rpa equations for short @xcite .
concrete examples are furnished by the vibrational excitations of a solid , the spin waves of a magnet , the electromagnetic modes of an optical medium , or the density oscillations of a bose - einstein condensate . constrained by the requirement of dynamical stability ,.
Please generate the next two sentences of the article | the hamiltonian @xmath2 of any vibrational or quasi - boson system of the mentioned kind must lie in a positive cone , @xmath3 , of so - called elliptic symplectic generators .
it should be stressed that although @xmath2 is hermitian as an operator in fock space , the quantum - to - classical mapping sends @xmath2 to an rpa generator @xmath4 which is in general neither hermitian nor anti - hermitian as a linear operator on the classical phase space . in view of this , a distinctive feature of the set of elliptic generators @xmath5 is that they can be brought to diagonal form ( with real frequencies , corresponding to stable oscillatory motion ) by real bogoliubov transformations , i.e. , by conjugating with elements of the real symplectic group @xmath6 . in this general |
7,114 | Suppose that you have an abstract for a scientific paper: the van der waals quintessence equation of state is an interesting scenario for describing the late universe , and seems to provide a solution to the puzzle of dark energy , without the presence of exotic fluids or modifications of the friedmann equations . in this work
, the construction of inhomogeneous compact spheres supported by a van der waals equation of state is explored .
these relativistic stellar configurations shall be denoted as _ van der waals quintessence stars_. despite of the fact that , in a cosmological context , the van der waals fluid is considered homogeneous , inhomogeneities may arise through gravitational instabilities . thus , these solutions may possibly originate from density fluctuations in the cosmological background .
two specific classes of solutions , namely , gravastars and traversable wormholes are analyzed .
exact solutions are found , and their respective characteristics and physical properties are further explored . .
And you have already written the first three sentences of the full article: the universe is presently undergoing an accelerated phase of expansion .
several candidates have been proposed in the literature to explain this cosmic accelerated expansion , such as dark energy models , the generalized chaplygin gas , modified gravity and scalar - tensor theories , tachyon scalar fields and specific braneworld models , such as the dvali - gabadadze - porrati ( dgp ) model .
however , it was pointed out that assuming that dark energy is governed by a perfect fluid equation of state may systematically induce wrong results and be misleading in inferring the nature of dark energy @xcite . in this spirit.
Please generate the next two sentences of the article | , an alternative model was recently proposed without the presence of exotic fluids and modifications of the friedmann equations , using a more complicated equation of state , namely , the van der waals ( vdw ) equation of state @xcite , given by @xmath0 where @xmath1 is the energy density and @xmath2 the pressure of the vdw fluid .
the accelerated and decelerated periods depend on the parameters , @xmath3 , @xmath4 and @xmath5 of the equation of state , and in the limiting case @xmath6 , one recovers the dark energy equation of state , with @xmath7 . |
7,115 | Suppose that you have an abstract for a scientific paper: we revise the notion of the _ quasi - sectorial _ contractions .
our main theorem establishes a relation between semigroups of _ quasi - sectorial _ contractions and a class of @xmath0sectorial generators .
we discuss a relevance of this kind of contractions to the theory of operator - norm approximations of strongly continuous semigroups .
operator numerical range ; @xmath1-sectorial generators ; contraction semigroups ; quasi - sectorial contractions ; holomorphic semigroups ; semigroup operator - norm approximations .
47a55 , 47d03 , 81q10 .
And you have already written the first three sentences of the full article: let @xmath2 be a separable hilbert space and let @xmath3 be a densely defined linear operator with domain @xmath4 .
[ def - n - ran ] _ the set of complex numbers : @xmath5 is called the _ numerical range _ of the operator @xmath3 .
_ [ rem-1 - 1 ] ( a ) it is known that the set @xmath6 is convex ( the toeplitz - hausdorff theorem ) , and in general is neither open nor closed , even for a closed operator @xmath3 ..
Please generate the next two sentences of the article | + ( b ) let @xmath7 be complement of the numerical range closure in the complex plane .
then @xmath8 is a connected open set except the special case , when @xmath9 is a strip bounded by two parallel straight lines . |
7,116 | Suppose that you have an abstract for a scientific paper: we present the first direct image of the high - metallicity gas component in a planetary nebula ( ngc6778 ) , taken with the osiris blue tunable filter centered on the o ii @xmath04649 + 50 optical recombination lines ( orls ) at the 10.4 m gran telescopio canarias .
we show that the emission of these faint o ii orls is concentrated in the central parts of the planetary nebula and is not spatially coincident either with emission coming from the bright [ o iii ] @xmath05007 collisionally excited line ( cel ) or the bright h@xmath1 recombination line . from monochromatic emission line maps taken with vimos at the 8.2 m very large telescope ,
we find that the spatial distribution of the emission from the auroral [ o iii ] @xmath04363 line resembles that of the o ii orls but differs from nebular [ o iii ] @xmath05007 cel distribution , implying a temperature gradient inside the planetary nebula . the centrally peaked distribution of the o ii emission and the differences with the [ o iii ] and hi emission profiles are consistent with the presence of an h - poor gas whose origin may be linked to the binarity of the central star .
however , determination of the spatial distribution of the orls and cels in other pne , and a comparison of their dynamics is needed to further constrain the geometry and ejection mechanism of the metal - rich ( h - poor ) component and hence , understand the origin of the abundance discrepancy problem in pne . .
And you have already written the first three sentences of the full article: in photoionized nebulae both h ii regions and planetary nebulae ( pne) optical recombination lines ( orls ) provide abundance values that are systematically larger than those obtained using collisionally excited lines ( cels ) ( see e. g. * ? ? ?
* ; * ? ? ?
* , and references therein ) ..
Please generate the next two sentences of the article | this is known as the _ abundance discrepancy problem_. it is one of the major unresolved problems in nebular astrophysics , being known of for more than seventy years @xcite , and has far - reaching consequences on the measurement of abundances throughout the universe , most often measured using cels from ionized gas .
the abundance discrepancy factor ( _ adf _ ) is defined as the ratio between the abundances derived from orls and cels and is usually between 1.5 and 3 ( see e. g. * ? ? ? |
7,117 | Suppose that you have an abstract for a scientific paper: using a recently proposed ginzburg - landau - like lattice free energy functional due to banerjee et al .
phys . rev .
b 83 , 024510 ( 2011 ) we calculate the fluctuation diamagnetism of high-@xmath0 superconductors as a function of doping , magnetic field and temperature .
we analyse the pairing fluctuations above the superconducting transition temperature in the cuprates , ranging from the strong phase fluctuation dominated underdoped limit to the more conventional amplitude fluctuation dominated overdoped regime . we show that a model where the pairing scale increases and the superfluid density decreases with underdoping produces features of the observed magnetization in the pseudogap region , in good qualitative and reasonable quantitative agreement with the experimental data . in particular , we explicitly show that even when the pseudogap has a pairing origin the magnetization actually tracks the superconducting dome instead of the pseudogap temperature , as seen in experiment .
we discuss the doping dependence of the ` onset ' temperature for fluctuation diamagnetism and comment on the role of vortex core - energy in our model . .
And you have already written the first three sentences of the full article: in recent years fluctuation diamagnetism and the nernst effect in the pseudogap regime of cuprate superconductors have generated great interest both theoretically @xcite and experimentally @xcite .
experiments have found a very large diamagnetic and nernst response in the enigmatic pseudogap phase of the cuprates .
a large diamagnetic signal naturally points towards fluctuating superconductivity as one of the possible origins ..
Please generate the next two sentences of the article | also , the fact that the nernst response is usually very small in typical nonmagnetic metals and a much stronger response is observed in the vortex - liquid regime as is expected in a fluctuating superconductor supports this point of view .
compared to conventional superconductors , the nernst and diamagnetic response have been found to exist over an anomalously large region @xcite in the pseudogap phase , extending to temperatures far above the superconducting transition temperature @xmath0 ( see however ref . ) . |
7,118 | Suppose that you have an abstract for a scientific paper: we investigate the gluon , ghost and quark propagators in the landau gauge with dynamic quarks .
we perform a one - loop calculation in a model where the standard faddeev - popov lagrangian is complemented by a mass term for the gluons which is seen as a minimal way of taking into account the effect of the gribov copies .
the analytic results are compared with lattice data obtained in four dimension and for two , three and four quark flavors .
the gluon and ghost propagators are reproduced with a few percent accuracy in the whole range of accessible momenta .
the scalar part of the quark propagator is found to be in good agreement with the lattice data .
however , the quark renormalization is poorly described .
we attribute this discrepancy to the fact that the one - loop corrections to this quantity are unusually small so that the two loop contribution can not be discarded .
the results are expressed in terms of the coupling , the gluon mass and the light quark mass at 1 gev . .
And you have already written the first three sentences of the full article: it is well - known that the faddeev - popov construction , which is the standard analytic method for fixing the gauge , is not sufficient in order to treat the infrared regime of qcd .
the problem originates in the existence of gribov copies @xcite which are ignored in the faddeev - popov construction .
gribov copies do not play any role in the ultraviolet regime ..
Please generate the next two sentences of the article | for that reason , the yang - mills action complemented by the faddeev - popov action is a good starting point to analyze both gauge - invariant and non - invariant quantities at momentum scales much bigger than @xmath0 gev .
however , at low momenta the question of how to include the effect of gribov copies in a lagrangian still remains unsolved even though some ideas have been already developed . among those , |
7,119 | Suppose that you have an abstract for a scientific paper: many - particle electron states in semiconductor quantum dots with carrier - mediated ferromagnetism are studied theoretically within the self - consistent boltzmann equation formalism .
depending on the conditions , a quantum dot may contain there phases : partially spin - polarized ferromagnetic , fully spin - polarized ferromagnetic , and paramagnetic phases .
the physical properties of many - body ferromagnetic confined systems come from the competing carrier - mediated ferromagnetic and coulomb interactions .
the magnetic phases in gated quantum dots with holes can be controlled by the voltage or via optical methods . .
And you have already written the first three sentences of the full article: diluted magnetic semiconductors @xcite represent an important class of materials and structures where ferromagnetism can be tuned by voltage @xcite .
this ability comes from the carrier - mediated character of the ferromagnetic interaction @xcite .
the ferromagnetic ordered state in these systems appears due to mobile carriers interacting with stationary spins of magnetic impurities . to date.
Please generate the next two sentences of the article | , curie temperatures as high as @xmath0 have been observed in a technologically important class of the mn - doped iii - v semiconductor structures @xcite . when the magnetic semiconductors become combined with the conventional field - effect layered structures , the number of mobile carriers and the ferromagnetic interaction become tunable by the voltage @xcite .
this ability to externally control the properties of magnetic crystals with means other than the external magnetic field may have important device applications . |
7,120 | Suppose that you have an abstract for a scientific paper: we construct an utility - based dynamic asset pricing model for a limit order market .
the price is nonlinear in volume and subject to market impact .
we solve an optimal hedging problem under the market impact and derive the dynamics of the efficient price , that is , the asset price when a representative liquidity demander follows an optimal strategy .
we show that a pareto efficient allocation is achieved under a completeness condition .
we give an explicit representation of the efficient price for several examples .
in particular , we observe that the volatility of the asset depends on the convexity of an initial endowment .
further , we observe that an asset price crash is invoked by an endowment shock .
we establish a dynamic programming principle under an incomplete framework .
* keywords : * utility indifference principle ; market impact ; efficient price ; + quadratic backward stochastic differential equation ; burgers equation . +
* jel classification : * g12 ; g13 . *
msc2010 :* 91b25 ; 91g80 . .
And you have already written the first three sentences of the full article: we are interested in the dynamics of an asset price in a limit order market .
we aim at constructing a tractable model which captures endogenously such phenomena observed in actual markets as nonlinearity in liquidation , permanent market impact and a flash crash due to illiquidity .
the liquidity issue has been pointed out as a major risk which standard models of financial engineering have not taken into consideration . the failures of several financial institutions are often attributed to the uncovered liquidity risk ..
Please generate the next two sentences of the article | the liquidity crisis is a rare event ; an exogenous statistical modeling of liquidity costs is therefore not sufficient for preparing ourselves for a future crisis .
an economic consideration is required for a deeper understanding of the liquidity risk . |
7,121 | Suppose that you have an abstract for a scientific paper: we analyzed the spatial distribution of @xmath0 photometrically selected galaxies with magnitude @xmath1 and redshift @xmath2 in 21 fields with a total area of @xmath3 square degrees .
the galaxies were divided into three subsamples , with mean redshifts @xmath4 , @xmath5 , @xmath6 , according to the @xmath7 selection criteria of adelberger et al .
( 2004 ) and steidel et al .
( 2003 ) . combining the galaxies measured angular clustering with redshift distributions inferred from @xmath8 spectroscopic redshifts , we find comoving correlation lengths at the three redshifts of @xmath9 , @xmath10 , and @xmath11 mpc , respectively , and infer a roughly constant correlation function slope of @xmath12 .
we derive similar numbers from the @xmath8 object spectroscopic sample itself with a new statistic , @xmath13 , that is insensitive to many possible systematics .
galaxies that are bright in @xmath14 ( @xmath15@xmath16 ) cluster more strongly than fainter galaxies at @xmath17 and @xmath18 but not , apparently , at @xmath19 .
comparison to a numerical simulation that is consistent with recent wmap observations suggests that galaxies in our samples are associated with dark matter halos of mass @xmath20@xmath21 ( @xmath17 ) , @xmath22@xmath23 ( @xmath18 ) , @xmath24@xmath25 ( @xmath19 ) , and that a small fraction of the halos contain more than one galaxy that satisfies our selection criteria . adding recent observations of galaxy clustering at @xmath26 and @xmath27 to the simulation results , we conclude that the typical object in our samples will evolve into an elliptical galaxy by redshift @xmath28 and
will already have an early - type spectrum by redshift @xmath29 .
we comment briefly on the implied relationship between galaxies in our survey and those selected with other techniques . .
And you have already written the first three sentences of the full article: early investigators studied the spatial distribution of galaxies because they hoped to learn about the structure of the universe on the largest scales .
their influential work was superseded , in the end , by its competition .
problems began with the demonstration that galaxies contained only a small fraction of the matter in the universe ..
Please generate the next two sentences of the article | galaxy formation remained too poorly understood to quell doubts about how faithfully galaxies traced underlying distribution of dark matter .
other observations improved gravitational lensing , peculiar velocities , intergalactic absorption lines , and so on and seemed easier to relate to matter fluctuations . |
7,122 | Suppose that you have an abstract for a scientific paper: we have analyzed the double - lined eclipsing binary system ogle - lmc - cep-1812 in the lmc and demonstrate that it contains a classical fundamental mode cepheid pulsating with a period of 1.31 days .
the secondary star is a stable giant .
we derive the dynamical masses for both stars with an accuracy of 1.5% , making the cepheid in this system the second classical cepheid with a very accurate dynamical mass determination , following the ogle - lmc - cep-0227 system studied by pietrzynski et al .
( 2010 )
. the measured dynamical mass agrees very well with that predicted by pulsation models .
we also derive the radii of both components and accurate orbital parameters for the binary system .
this new , very accurate dynamical mass for a classical cepheid will greatly contribute to the solution of the cepheid mass discrepancy problem , and to our understanding of the structure and evolution of classical cepheids . .
And you have already written the first three sentences of the full article: classical cepheids have been key objects in the long - lasting efforts to measure the extragalactic distance scale and to probe the predictions of stellar evolution and stellar pulsation theory ( e.g. freedman and madore 2010 , caputo et al . 2005 ) . given the enormous importance of cepheids for the determination of the cosmic distance scale and cosmological parameters , it is of great importance to fully understand these stars astrophysically .
one of the most nagging problems in cepheid research has been the difficulty to reliably determine their masses .
christy ( 1968 ) and stobie ( 1969 ) were the first to notice that cepheid masses calculated from stellar pulsational theory were about 20 % smaller than the corresponding masses estimated from their evolutionary tracks on the hertzsprung - russell diagram . in spite of the considerable progress in understanding the physics of cepheid variable stars over the years.
Please generate the next two sentences of the article | , the `` cepheid mass discrepancy problem '' has remained unsolved for more than 40 years ( keller and wood 2002 , keller 2008 , evans et al .
2008 , caputo et al . |
7,123 | Suppose that you have an abstract for a scientific paper: a theoretical analysis of the thermodynamic properties of the robin wall characterized by the extrapolation length @xmath0 in the electric field @xmath1 that pushes the particle to the surface is presented both in the canonical and two grand canonical representations and in the whole range of the robin distance with the emphasis on its negative values which for the voltage - free configuration support negative - energy bound state . for the canonical ensemble ,
the heat capacity at @xmath2 exhibits a nonmonotonic behavior as a function of the temperature @xmath3 with its pronounced maximum unrestrictedly increasing for the decreasing fields as @xmath4 and its location being proportional to @xmath5 . for the fermi - dirac distribution ,
the specific heat per particle @xmath6 is a nonmonotonic function of the temperature too with the conspicuous extremum being preceded on the @xmath3 axis by the plateau whose magnitude at the vanishing @xmath1 is defined as @xmath7 , with @xmath8 being a number of the particles .
the maximum of @xmath6 is the largest for @xmath9 and , similar to the canonical ensemble , grows to infinity as the field goes to zero . for the bose - einstein ensemble ,
a formation of the sharp asymmetric feature on the @xmath6-@xmath3 dependence with the increase of @xmath8 is shown to be more prominent at the lower voltages .
this cusp - like dependence of the heat capacity on the temperature , which for the infinite number of bosons transforms into the discontinuity of @xmath10 , is an indication of the phase transition to the condensate state .
some other physical characteristics such as the critical temperature @xmath11 and ground - level population of the bose - einstein condensate are calculated and analyzed as a function of the field and extrapolation length .
qualitative and quantitative explanation of these physical phenomena is based on the variation of the energy spectrum by the electric field . .
And you have already written the first three sentences of the full article: analysis of the interaction between the electric field @xmath1 applied perpendicularly to the plane @xmath12 and the robin boundary condition ( bc ) at it @xcite @xmath13 has shown that the spectrum of the one - dimensional quantum particle of the mass @xmath14 moving on the half - line @xmath15 and satisfying the schrdinger equation for the wave function @xmath16 and energy @xmath17 , @xmath18 , @xmath19 for the finite nonzero extrapolation length @xmath0 is determined from the transcendental equation @xcite @xmath20^{1/3}\!\!e_n\right)-\frac{1}{\lambda}\,{\rm ai}\!\left(-\left[\frac{2m}{(e\hbar\mathscr{e})^2}\right]^{1/3}\!\!e_n\right)=0.\ ] ] here , @xmath21 is an inward unit normal to the interface @xmath12 , @xmath22 is an electrostatic potential @xmath23 creating the field @xmath24 that pushes the particle ( for definiteness , we will talk about the electron with its negative charge @xmath25 ) closer to the surface , @xmath26 is airy function @xcite and prime denotes its derivative with respect to argument @xmath27 . for @xmath28 ( @xmath29 ) the bc from eq .
simplifies to the dirichlet ( neumann ) requirement @xmath30 [ @xmath31 with the energy spectrum directly following from eq . :
@xmath32 where the negative @xmath33 and @xmath34 are @xmath35th roots , @xmath36 , of the equations @xmath37 or @xmath38 , respectively @xcite ..
Please generate the next two sentences of the article | for the small nonzero parameter @xmath39 the taylor expansion of eq .
shows that the first - order correction to the dirichlet spectrum is equal to the voltage drop across the robin distance : [ asymptoticenergies1 ] @xmath40,\nonumber\\ \label{asymptoticenergies1_dirichlet0 } & \frac{2me\mathscr{e}|\lambda|^3}{\hbar^2}\ll1.\\ \intertext{in the opposite limit the energies are : } \label{asymptoticenergies1_neumann } & e_n^{r\mp}=-a_{n+1}'\left(\frac{e^2\hbar^2\mathscr{e}^2}{2m}\right)^{1/3}\left[1\mp\frac{1}{{a_{n+1}'}^{\!\!\!\!\!\!\!\!2}\,\,\,\,}\left(\frac{\hbar^2}{2me\mathscr{e}|\lambda|^3}\right)^{1/3}\right],\nonumber\\ & n=0,1,2,\ldots,\quad\frac{\hbar^2}{2me\mathscr{e}|\lambda|^3}\ll1.\end{aligned}\ ] ] eq . |
7,124 | Suppose that you have an abstract for a scientific paper: semi - insulating , undoped , liquid encapsulated czochralski ( si - u lec ) gaas detectors have been irradiated with 1mev neutrons , 24gev / c protons , and 300mev / c pions .
the maximum fluences used were 6 , 3 , and 1.8 10@xmath0 particles/@xmath1 respectively . for all three types of irradiation
the charge collection efficiencies ( cce ) of the detector are reduced due to the reduction in the electron and hole mean free paths .
pion and proton irradiations produce a greater reduction in cce than neutron irradiation , with the pions having the greatest effect .
the effect of annealing the detectors at room temperature , at 200@xmath2c and at 450@xmath2c with a flash lamp have been shown to reduce the leakage current and increase the cce of the irradiated detectors .
the flash - lamp anneal produced the greatest increase in the cce from 26% to 70% by increasing the mean free path of the electrons .
two indium - doped samples were irradiated with 24gev / c protons and demonstrated no improvement over si u gaas with respect to post - irradiation cce .
glas - ppe/970427 august 1997 .
And you have already written the first three sentences of the full article: the possible use of gaas detectors in the future atlas experiment at the lhc imposes severe demands on the radiation hardness of the gaas detectors .
semi - insulating , undoped gaas detectors have been shown to withstand doses up to 100mrad of @xmath3co gamma rays @xcite . their sensitivity to neutrons , protons and pions
are reported in this paper ..
Please generate the next two sentences of the article | the irradiations were performed at the isis facility @xcite for the neutron exposure , with a spectrum strongly peaked at 1mev , the cern ps for 24gev / c protons @xcite and the psi , villigen , for 300mev / c pions @xcite .
all irradiations were performed at room temperature . |
7,125 | Suppose that you have an abstract for a scientific paper: we state a general formula to compute the volume of the intersection of the regular @xmath0-simplex with some @xmath1-dimensional subspace .
it is known that for central hyperplanes the one through the centroid containing @xmath2 vertices gives the maximal volume .
we show that , for fixed small distances of a hyperplane to the centroid , the hyperplane containing @xmath2 vertices is still volume maximizing .
the proof also yields a new and short argument for the result on central sections . with the same technique
we give a partial result for the minimal central hyperplane section .
finally , we obtain a bound for @xmath1-dimensional sections . .
And you have already written the first three sentences of the full article: given a convex body @xmath3 and some subspace @xmath4 , how to compute the volume of the intersection @xmath5 ?
how to find the maximal or minimal sections ?
these questions have been considered for various convex bodies ..
Please generate the next two sentences of the article | a first example is the unit cube intersected with central hyperplanes .
explicit formulas were already found by laplace . the question of the minimal and the maximal section were answered by d. hensley @xcite resp . k. ball @xcite . since then |
7,126 | Suppose that you have an abstract for a scientific paper: motivated by the sharp contrast between classical and quantum physics as probability theories , in these lecture notes i introduce the basic notions of operator algebras that are relevant for the algebraic approach to quantum physics .
aspects of the representation theory of c*-algebras will be motivated and illustrated in physical terms .
particular emphasis will be given to explicit examples from the theory of quantum phase transitions , where concepts coming from strands as diverse as quantum information theory , algebraic quantum physics and statistical mechanics agreeably converge , providing a more complete picture of the physical phenomena involved . .
And you have already written the first three sentences of the full article: this notes represent the written version of lectures i gave in mini - courses at universidade de braslia ( april 3 - 6 , 2013 ) , universidad central de venezuela ( may 23 - 27 , 2016 ) and at the villa de leyva summer school `` geometric , topological and algebraic methods for quantum field theory '' ( july 15 - 27 , 2013 ) .
they were mainly intended as an introduction to some aspects of operator algebras , emphasizing the prominent role they play in quantum physics . as the audience consisted of students of both physics and mathematics at different stages of their studies ,
my choice was to focus on the most basic structures and examples , in the hope that a good grasp of these would motivate them to go deeper into the subject ..
Please generate the next two sentences of the article | now , something that to a physicist may appear as completely familiar ( as , say , an experimental set - up with polarizers , or the distinction between a classical and a quantum field ) to a mathematician may not
. the same could be said of the proof that the spectrum of any element in a @xmath0-algebra is never empty : it is a standard result in analysis , but may look quite awkward to many physics students . |
7,127 | Suppose that you have an abstract for a scientific paper: in analogy to brownian computers we explicitly show how to construct stochastic models , which mimic the behaviour of a general purpose computer ( a turing machine ) .
our models are discrete state systems obeying a markovian master equation , which are logically reversible and have a well - defined and consistent thermodynamic interpretation . the resulting master equation , which describes a simple one - step process on an enormously large state space , allows us to thoroughly investigate the thermodynamics of computation for this situation . especially , in the stationary regime we can well approximate the master equation by a simple fokker - planck equation in one dimension .
we then show that the entropy production rate at steady state can be made arbitrarily small , but the total ( integrated ) entropy production is finite and grows logarithmically with the number of computational steps . .
And you have already written the first three sentences of the full article: computers are physical systems and information has to be stored and transmitted using physical devices .
this trivially sounding statement has led to very important insights as soon as one starts to ask for the fundamental physical limits of computation .
the most known statement is probably landauer s principle : erasing a data set with information content ( i.e. , entropy ) @xmath0 causes a minimum heat dissipation of @xmath1 if @xmath2 is the inverse temperature of the surrounding environment ..
Please generate the next two sentences of the article | this was first formulated by landauer in 1961 @xcite . more generally , it was argued by bennett @xcite and others @xcite , that each logically irreversible operation ( as , e.g. , information erasure ) must be accompanied with a corresponding heat dissipation whereas _
each logically reversible operation can be implemented at least in principle in an energetically neutral way . _ |
7,128 | Suppose that you have an abstract for a scientific paper: determination of the orbital angular momentum of the proton is a difficult but important part of understanding fundamental structure .
insight can be gained from suitable models of the gluon asymmetry applied to the @xmath0 sum rule .
we have constrained the models of the asymmetry to gain possible scenarios for the angular momentum of the protons constituents .
results and phenomenology for determining @xmath1 are presented . .
And you have already written the first three sentences of the full article: for the past twenty years , much work has been done to understand the spin structure of the nucleons .
there has been progress in determining the contribution of the lightest quarks to the spin , but there is still uncertain knowledge about the gluon contribution .
transversity studies have contributed additional insight about quark dynamics , but little is known about the the orbital angular momentum of the constituents.@xcite this paper will summarize a project that provides a method of gaining insight into the nature of the orbital angular momentum of the nucleon constituents ..
Please generate the next two sentences of the article | recent experiments @xcite have significantly lowered the measurement errors of the quark longitudinal spin contribution ( @xmath2 ) to the proton .
the compass collaboration analysis quotes a result @xmath3 while the hermes collaboration analysis quotes a result @xmath4 these groups and others @xcite have been working on providing a significant measure of the proton s spin weighted gluon density , @xmath5 where @xmath6 is the bjorken scaling variable and @xmath7 is the @xmath8 evolution variable . |
7,129 | Suppose that you have an abstract for a scientific paper: we study the analytic continuation used by lewkowycz and maldacena to prove the ryu - takayanagi formula for entanglement entropy , which is the holographic dual of the trace of the @xmath0-power of the time evolution operator when @xmath1 .
this will be done perturbatively by using a weakly time dependent hamiltonian , corresponding to a small shift of the dual static background .
depending on the periodicity we impose on the gravitational solution , we consider two different possibilities and compare the associated entropies with the results obtained through a minimal area computation . to our surprise
we discover that , at first order , both choices correctly reproduce the associated entanglement entropy .
furthermore we find unexpected divergent contributions that we have to discard in order to fit the minimal area computation , and an additional requirement that needs to be imposed on the @xmath0 dependence on the metric . * a perturbative study on the analytic continuation for generalized gravitational entropy * + andrea prudenziati 2em .
And you have already written the first three sentences of the full article: entanglement entropy has been an intensively studied subject in the last few years , and indeed a primary role has been played by the well known formula for its holographic computation . given a fixed time codimension one submanifold @xmath2 , with its complement @xmath3 , and a density matrix @xmath4 , the entanglement entropy is defined to be the von neumann entropy for the reduced density matrix @xmath5 $ ] , where @xmath6 ( resp .
@xmath7 ) is the hilbert space living on @xmath2 ( resp . @xmath3 ): @xmath8 $ ] .
then , if we have a dual static euclidean background , @xcite proposed the formula @xmath9 where @xmath10 is the newton constant in the holographic @xmath11 dimensional space @xmath12 , and @xmath13 is the minimal surface area inside @xmath12 , extending towards @xmath14 where the boundary @xmath15 is located , and such that @xmath16 . not only this remarkable formula provides a relatively simple computational tool for @xmath17 , so far only possible at weak coupling using the replica trick for path integration , it also allowed many new developments in studying the properties of entanglement entropy ..
Please generate the next two sentences of the article | we may mention for example an alternative proof of the c - theorem and possible higher dimensional generalizations @xcite ; numerous achievements in reconstructing bulk and gravity properties from field theory data , for instance @xcite @xcite @xcite and @xcite , in particular enlightening the connection between gravity equations of motion and a sort of thermodynamic first law for entanglement entropy @xcite ( extended to a zeroth and second law in @xcite ) .
further the ryu - takayanagi formula may be used to construct an incredibly simple proof of strong subadditivity @xcite , although its counterpart for time dependent backgrounds looks more tricky and deeply interconnected with the null energy condition @xcite , and for instance @xcite @xcite for the case of vaidya space . |
7,130 | Suppose that you have an abstract for a scientific paper: we consider chiral blocks of four ramond fields of the @xmath0 super virasoro algebra where one of the fields is in the ( 1,2 ) representation . we show how the null vector in the ( 1,2 ) representation determines the chiral blocks as series expansions .
we then turn to the ising model to find an algebraic method to determine differential equations for the blocks of four spin fields . extending these ideas to the super virasoro case
, we find a first order differential equation for blocks of four ramond fields .
we are able to find exact solutions in many cases .
we compare our blocks with results known from other methods . .
And you have already written the first three sentences of the full article: conformal field theories in two dimensions can be used to describe string theory from the worldsheet perspective and statistical systems at a second order phase transition .
the study of these field theories is often manageable because the infinite dimensional symmetry algebras which exist can reduce the field content to a finite number of representations . in such minimal cases , there are ` null vectors ' which should decouple from all correlation functions . as a result
the non - zero correlation functions satisfy differential equations which enable one to solve the theory completely ..
Please generate the next two sentences of the article | each symmetry algebra has its own series of minimal models for which this procedure works .
the simplest case is that of minimal models of the virasoro algebra . in @xcite , belavin |
7,131 | Suppose that you have an abstract for a scientific paper: we propose a universal scheme for the probabilistic generation of an arbitrary multimode entangled state of light with finite expansion in fock basis .
the suggested setup involves passive linear optics , single photon sources , strong coherent laser beams , and photodetectors with single - photon resolution .
the efficiency of this setup may be greatly enhanced if , in addition , a quantum memory is available . .
And you have already written the first three sentences of the full article: the generation of nonclassical states of light is one of the primary research areas in quantum optics .
in particular , the preparation of _ entangled states _ of light has attracted a considerable amount of attention recently , since these states have been identified as a key resource for quantum information processing @xcite .
other interesting applications of the entangled states include , for instance , ultra - high precision measurements @xcite and quantum optical lithography @xcite ..
Please generate the next two sentences of the article | the range of interactions between light fields that are experimentally accessible and feasible is rather limited , which restricts the class of quantum states of the optical field that can be generated in the lab .
however , this class can be significantly extended if one considers probabilistic generation schemes , whose success is conditioned on the detection of a particular outcome of a measurement performed on some ancilla system . |
7,132 | Suppose that you have an abstract for a scientific paper: a scalar singlet , coupled to the other particles only through its mixing with the higgs boson , appears in several motivated extensions of the standard model .
the prospects for the discovery of a generic singlet at the various stages of the lhc , as well as at future high - energy colliders , are studied , and the reach of direct searches is compared with the precision attainable with higgs couplings measurements .
the results are then applied to the nmssm and twin higgs .
= 11.6pt .
And you have already written the first three sentences of the full article: is the higgs boson recently found by the atlas and cms experiments the only scalar particle , or are there other higgs - like states around the fermi scale ?
this question is of fundamental importance for particle physics , and motivates a detailed study of the phenomenology of additional scalars , as well as the prospects for their discovery at the lhc and future colliders@xcite .
the simplest example of an extended higgs sector is realised adding just a real scalar field , singlet under all the known gauge groups , to the standard model ( sm ) . despite its great simplicity ,.
Please generate the next two sentences of the article | this scenario is of considerable physical relevance , since it can easily arise in many of the most natural extensions of the sm
e.g. the next - to - minimal supersymmetric sm ( nmssm ) , twin higgs , some composite higgs models . |
7,133 | Suppose that you have an abstract for a scientific paper: we give uniform , explicit , and simple face - pairing descriptions of all the branched cyclic covers of the 3sphere , branched over two - bridge knots .
our method is to use the bi - twisted face - pairing constructions of cannon , floyd , and parry ; these examples show that the bi - twist construction is often efficient and natural .
finally , we give applications to computations of fundamental groups and homology of these branched cyclic covers . .
And you have already written the first three sentences of the full article: branched cyclic covers of @xmath0 have played a major role in topology , and continue to appear in a wide variety of contexts . for example , branched cyclic covers of @xmath0 branched over two - bridge knots have recently appeared in combinatorial work bounding the matveev complexity of a 3-manifold @xcite , in algebraic and topological work determining relations between @xmath1-spaces , left - orderability , and taut foliations @xcite , and in geometric work giving information on maps of character varieties @xcite .
they provide a wealth of examples , and a useful collection of manifolds on which to study conjectures . given their wide applicability , and their continued relevance , it is useful to have many explicit descriptions of these manifolds . in this paper , we give a new and particularly elegant construction of the branched cyclic covers of two - bridge knots , using the bi - twist construction of @xcite .
while other presentations of these manifolds are known ( see , for example @xcite ) , we feel our descriptions have several advantages , as follows ..
Please generate the next two sentences of the article | first , they follow from a recipe involving exactly the parameters necessary to describe a two - bridge knot , namely , continued fraction parameters .
our descriptions apply uniformly to all two - bridge knots , and all branched cyclic covers of @xmath0 branched over two - bridge knots . |
7,134 | Suppose that you have an abstract for a scientific paper: we study a particle propagation on a circle in the presence of a point interaction .
we show that the one - particle feynman kernel can be written into the sum of reflected and transmitted trajectories which are weighted by the elements of the @xmath0-th power of the scattering matrix evaluated on a line with a point interaction . as a by - product we find three - parameter family of trace formulae as a generalization of the poisson summation formula . .
And you have already written the first three sentences of the full article: quantum system restricted on a bounded domain has become more relevant for theoretical physics . there , the role of boundary conditions are very important not only for the long distance ( infrared ) regime but also for the short distance ( ultraviolet ) regime .
mathematically , the correct framework to treat the boundary conditions in quantum theory is by means of the analysis of von neumann s self - adjoint extension of the hamiltonian operator @xcite . physically speaking
, the variety of boundary conditions provided by the self - adjoint extension of the hamiltonian implies that the very rich structure of point interactions available in quantum theory ..
Please generate the next two sentences of the article | the analysis of self - adjoint extension of the hamiltonian , as the name suggests , is essentially based on the hamiltonian operator approach .
however , in the feynman s path - integral approach , we do not know _ a priori _ how to incorporate the boundary conditions into the integration measure nor into the path - integral weight . as discussed in many textbooks |
7,135 | Suppose that you have an abstract for a scientific paper: a method for embedding graphs in euclidean space is suggested .
the method connects nodes to their geographically closest neighbors and economizes on the total physical length of links .
the topological and geometrical properties of scale - free networks embedded by the suggested algorithm are studied both analytically and through simulations .
our findings indicate dramatic changes in the embedded networks , in comparison to their off - lattice counterparts , and call into question the applicability of off - lattice scale - free models to realistic , everyday - life networks . , , , , internet , scale - free , networks , embedding , lattice 89.75.hc , 05.50.+q , 89.75.da .
And you have already written the first three sentences of the full article: the internet and the world wide web ( www ) , the electricity power grid , networks of flight connections , of social contacts , and neuronal networks of the brain are few of the many examples of networks that surround us and that may be usefully described as graphs @xcite .
graph theory is rooted in the 18th century , beginning with the work of euler .
early efforts focused on properties of special ( and usually small ) graphs . in the 1960s ,.
Please generate the next two sentences of the article | paul erds and alfrd rnyi @xcite initiated the study of _ random graphs _ , known also as er graphs .
the unlimited size and randomness of er graphs made them natural contenders for models of large networks encountered in everyday life . in 1967 |
7,136 | Suppose that you have an abstract for a scientific paper: we have determined the abundance of @xmath0-band drop - outs in the _
hst_/acs goods surveys and the hubble ultra deep field ( udf ) .
the majority of these sources are likely to be @xmath1 galaxies whose flux decrement between the f775w @xmath0-band and f850lp @xmath2-band arises from lyman - alpha absorption . we have shown with keck / deimos and gemini / gmos spectroscopy that this technique does indeed select high redshift galaxies , and we discovered lyman-@xmath3 emission in the expected redshift range for about a third of the galaxies with @xmath4 in the 150arcmin@xmath5 of the goods - south field .
the @xmath6-drop number counts in the goods - north field are consistent , so cosmic variance is possibly not the dominant uncertainty .
the increased depth of udf enables us to reach a @xmath7 limiting magnitude of @xmath8 ( equivalent to @xmath9 at @xmath10 , or @xmath11 for the @xmath12 @xmath13-drop population ) .
the star formation rate at @xmath1 was approximately @xmath14 _ less _ than at @xmath12 .
this declining comoving star formation rate ( @xmath15 at @xmath1 at @xmath16 for a salpeter imf ) poses an interesting challenge for models which suggest that @xmath16 star forming galaxies at @xmath17 reionized the universe .
the short - fall in ionizing photons might be alleviated by galaxies fainter than our limit , or a radically different imf .
alternatively , the bulk of reionization might have occurred at @xmath18 .
we have recently discovered evidence of an early epoch of star formation in some of the @xmath0-drops at @xmath1 . _
spitzer _ images with irac at @xmath19 m show evidence of the age - sensitive balmer/4000 , dominated by stars older than 100myr ( and most probably 400myr old ) .
this pushes the formation epoch for these galaxies to @xmath20 .
there are at least some galaxies already assembled with stellar masses @xmath21 ( equivalent to @xmath22 today ) within the first billion years .
the early formation of such systems may have played a key role in....
And you have already written the first three sentences of the full article: there has been enormous progress over the past decade in discovering galaxies and qsos at increasingly high redshifts .
we are now probing far enough back in time that the universe at these early epochs was fundamentally different from its predominantly ionized state today .
observations of @xmath24 qsos ( becker et al ..
Please generate the next two sentences of the article | 2001 , fan et al .
2002 ) show near - complete absorption of flux at wavelengths short - ward of lyman-@xmath3 ( gunn & peterson 1965 ) , indicating that the universe is optically thick to this line , and that the neutral fraction of hydrogen is much greater than at lower redshifts . |
7,137 | Suppose that you have an abstract for a scientific paper: we investigate theoretically the effects of surface states over the magnetoresistance of ni - based organic spin - valves .
in particular we perform _ ab initio _ electronic transport calculations for a benzene - thiolate molecule chemically attached to a ni [ 001 ] surface and contacted either by te to another ni [ 001 ] surface , or terminated by a thiol group and probed by a ni stm tip . in the case of s- and te - bonded molecules we find a large asymmetry in the spin - currents as a function of the bias , although the @xmath0-@xmath1 is rather symmetric .
this leads to a smooth although not monotonic dependence of the magnetoresistance over the bias .
in contrast , in the case of a stm - type geometry we demonstrate that the spin - current and the magnetoresistance can be drastically changed with bias .
this is the result of a resonance between a spin - polarized surface state of the substrate and the @xmath2-shell band - edge of the tip . .
And you have already written the first three sentences of the full article: the electron spin has recently made its appearance in organic electronics , generating a new field which takes the suggestive name of molecular - spintronics @xcite .
the main idea is to investigate how spin - currents propagate through organic molecules possibly affecting their internal state .
example of such spin - molecular devices are spin - valves made from carbon nanotubes @xcite , organic insulators @xcite or conducting polymers @xcite , fempto - second spectroscopy of molecular bridges connecting semiconductor nanodots @xcite and three terminal devices using magnetic molecules as active elements @xcite ..
Please generate the next two sentences of the article | organic molecules present genuine advantages over conventional inorganic metals and semiconductors .
typically the spin - orbit interaction , which scales with the atomic number @xmath3 as @xmath4 , is weak in molecules . |
7,138 | Suppose that you have an abstract for a scientific paper: we present results from an instrument combining surface acoustic wave ( saw ) propagation and surface plasmon resonance ( spr ) measurements .
the objective is to use two independent methods , the former based on adsorbed mass change measurements and the latter on surface dielectric properties variations , to identify physical properties of protein layers , and more specifically their water content .
we display mass sensitivity calibration curves using electrodeposition of copper leading to a sensitivity in liquid of 150@xmath0 @xmath1 for the love mode device used here , and the application to monitoring biological processes .
the extraction of protein layer thickness and protein to water content ratio is also presented for s - layer proteins under investigation .
we obtain respectively [email protected] nm and 75@xmath215% . .
And you have already written the first three sentences of the full article: surface plasmon resonance ( spr ) is a well accepted direct detection technique for monitoring biological processes @xcite . while ellipsometry is another well known method for analyzing thin film properties @xcite , its use in liquid medium for monitoring biochemical reactions
is made difficult by the varying environment through which the probing light beam has to propagate . in the kretschmann configuration , the laser generating the spr evanescent wave is only propagating through the substrate , leading to a better control over the influence of the various buffer solutions used during a protein adsorption experiment .
the use of various acoustic wave devices for monitoring bound mass changes in liquid media is well known @xcite ..
Please generate the next two sentences of the article | love mode devices , based on the propagation of a guided shear acoustic wave , present sensitivity improvements over the more usual quartz crystal microbalance @xcite as well as a compatibility with measurements in liquids .
we take advantage of the unique geometrical setup of the surface acoustic wave ( saw ) device which leaves the backside of the quartz wafer free of electrodes to inject a laser in order to generate an evanescent surface plasmon on the gold coated sensing area . |
7,139 | Suppose that you have an abstract for a scientific paper: we report the detection of x - ray emission from the hyperluminous infrared galaxy iras f15307 + 3252 at @xmath0 and its properties obtained from xmm - newton observations .
although the x - ray emission is very faint and the data are noisy , a prominent line - like feature in the observed 34 kev range is inferred from both photometric and spectroscopic techniques .
it indicates an x - ray spectrum dominated by 6.4 kev fe k@xmath1 emission and the presence of a compton - thick agn .
our estimate of the luminosity of the illuminating source ( @xmath2 ) , required to produce the observed fe k@xmath1 emission in reflection from cold matter , means that the hidden quasar nucleus accounts for a significant fraction of the large bolometric luminosity . the soft x - ray emission below 2 kev is found to be spatially extended and probably of a separate origin .
the temperature and bolometric luminosity ( @xmath3 kev and @xmath4 ) obtained from a thermal spectrum place this x - ray source on the @xmath5-@xmath6 relation of galaxy clusters .
the possible association with a galaxy cluster can be added to the list of remarkable similarities between iras f15307 + 3252 and another hyperluminous infrared galaxy iras 09104 + 4109 ( @xmath7 ) , both of which have bolometric luminosities dominated by hidden quasar nuclei .
our result on iras f15307 + 3252 illustrates how difficult it is to detect compton thick type ii quasars at @xmath8 , particularly if their bolometric outputs do not rival the hyperluminous population .
galaxies : individual : iras f15307 + 3252 x - rays : galaxies x - rays : galaxies : clusters infrared : galaxies .
And you have already written the first three sentences of the full article: the class of hyperluminous infrared galaxies , whose bolometric luminosities exceed @xmath9 , have been found through far - infrared and submillimetre surveys by iras and scuba ( e.g. , rowan - robinson 2000 ) , and more are expected from the spitzer space telescope .
some of them may be massive galaxies in formation at high redshift and , given the suggested link between galaxy spheroids and central black holes in them ( e.g. , tremaine et al 2002 ) , they might represent an important galaxy evolution phase where a quasar nucleus is forming amid heavy dust obscuration ( e.g. , sanders et al 1988 ) .
a population of mid - infrared - selected hyperluminous objects at @xmath10 , which appear to be powered mainly by obscured active galactic nuclei ( agn ) , are emerging from spitzer surveys ( houck et al 2005 ) . as well as the origin of the enormous luminosity being of a great interest , examining the role of luminous counterparts of nearby compton - thick seyfert agn to the x - ray background ( xrb ) and.
Please generate the next two sentences of the article | their detectability is also important , since the higher energy part of the xrb is not yet fully resolved ( worsley et al 2005 ) .
iras f15307 + 3252 is one of the few classical iras - selected hyperluminous infrared galaxies at redshift of @xmath11 ( cutri et al 1994 ) . with the currently popular cosmology with @xmath12 , @xmath13 , and @xmath14 , the luminosity distance is 6.1 gpc and and the bolometric luminosity is estimated to be @xmath15 . |
7,140 | Suppose that you have an abstract for a scientific paper: we present new observations of the fundamental ro - vibrational co spectrum of v1647 ori , the young star whose recent outburst illuminated mcneil s nebula .
previous spectra , acquired during outburst in 2004 february and july , had shown the co emission lines to be broad and centrally peaked similar to the co spectrum of a typical classical t tauri star . in this paper , we present co spectra acquired shortly after the luminosity of the source returned to its pre - outburst level ( 2006 february ) and roughly one year later ( 2006 december and 2007 february ) .
the spectrum taken in 2006 february revealed blue - shifted co absorption lines superimposed on the previously observed co emission lines .
the projected velocity , column density , and temperature of this outflowing gas was 30 km s@xmath0 , @xmath1 @xmath2 , and 700@xmath3 k , respectively .
the absorption lines were not observed in the 2006 december and 2007 february data , and so their strengths must have decreased in the interim by a factor of 9 or more .
we discuss three mechanisms that could give rise to this unusual outflow . .
And you have already written the first three sentences of the full article: mcneil s nebula was recently illuminated by the outburst of v1647 ori ( mcneil 2004 ) , a young star that is embedded in the lynds 1630 dark cloud and coincides with the 850@xmath4 continuum source oribsmm55 ( mitchell et al .
v1647 ori has a flat sed in the mid - infrared , and is thus a class i young stellar object ( yso ; andrews et al .
v1647 ori underwent a similar outburst as recently as 1966 ( aspin et al ..
Please generate the next two sentences of the article | 2006 ) , indicating that v1647 ori is also an exor .
such pre - main sequence stars undergo eruptive events that dramatically increase their luminosity for periods of months to years ( hartmann 1998 ) . |
7,141 | Suppose that you have an abstract for a scientific paper: we study a weakly disordered 2d electron gas with two bands and a spectral node within the weak - localization approach and compare its results with those of gaussian fluctuations around the self - consistent born approximation .
the appearance of diffusive modes depends on the type of disorder .
in particular , we find for a random gap a diffusive mode only from ladder contributions , whereas for a random scalar potential the diffusive mode is created by ladder and by maximally crossed contributions .
the ladder ( maximally crossed ) contributions correspond to fermionic ( bosonic ) gaussian fluctuations .
we calculate the conductivity corrections from the density density kubo formula and find a good agreement with the experimentally observed v - shape conductivity of graphene . .
And you have already written the first three sentences of the full article: the weak - localization approach ( wla ) has been a very popular tool to estimate whether electronic states in a weakly disordered system tend to localize or to delocalize on large scales .
moreover , it enables us to calculate the magnetoresistance in the presence of a weak magnetic field and weak scattering . a central result of
the wla is that on large scales there might be diffusion due to one or more massless modes ..
Please generate the next two sentences of the article | this has been studied in great detail for conventional metals @xcite and more recently for graphene @xcite and for the surface of topological insulators @xcite , using a one - band projection for the two - band system .
t he existence of a diffusive mode , which is a necessary ( but not a sufficient ) condition for metallic behavior , has been debated for the one - band projected graphene model . it was found that either a single diffusive channel exists @xcite or no diffusion @xcite in the presence of generic disorder . on the other hand , the weak - scattering approach ( wsa ) , where transport properties are studied within the expansion in powers of @xmath0 ( @xmath1 is the scattering rate and @xmath2 is the bandwidth ) @xcite , a non - abelian chiral symmetry was identified , describing diffusion in two - band systems due to spontaneous symmetry breaking @xcite . |
7,142 | Suppose that you have an abstract for a scientific paper: we examine the phenomenon of dynamical heterogeneity in computer simulations of an equilibrium , glass - forming liquid .
we describe several approaches to quantify the spatial correlation of single - particle motion , and show that spatial correlations of particle displacements become increasingly long - range as the temperature decreases toward the mode coupling critical temperature . .
And you have already written the first three sentences of the full article: liquids cooled toward their glass transition exhibit remarkable dynamical behavior @xcite .
the initial slowing down of many liquids at temperatures well above their glass transition temperature @xmath0 can be described to great extent by the mode coupling theory @xcite , which predicts diverging relaxation times at a dynamical critical temperature @xmath1 despite the absence of a diverging or even growing static correlation length @xcite . at the same time , experiments in the temperature range @xmath2 , and simulations in the range @xmath3 , have shown that it is possible to select subsets of particles in the liquid ( or monomers in the case of polymers ) that move differently from the bulk on time scales less than the structural relaxation time @xcite .
the question then arises as to whether glass - forming liquids exhibit _ spatially heterogeneous _ dynamics , and if so , is there a growing length scale associated with this dynamical heterogeneity ? we have employed three complementary computational approaches to address this question : 1 ..
Please generate the next two sentences of the article | _ subset approach .
_ in this approach @xcite , we monitor the displacement of each particle in a time window @xmath4 , rank the displacements from largest to smallest , and examine spatial correlations within subsets of particles exhibiting either extremely large or extremely small displacements . in this way |
7,143 | Suppose that you have an abstract for a scientific paper: a search for secluded dark matter annihilation in the sun using 2007 - 2012 data of the antares neutrino telescope is presented .
three different cases are considered : a ) detection of dimuons that result from the decay of the mediator , or neutrino detection from : b ) mediator that decays into a dimuon and , in turn , into neutrinos , and c ) mediator that decays directly into neutrinos . as no significant excess over background is observed , constraints are derived on the dark matter mass and the lifetime of the mediator . .
And you have already written the first three sentences of the full article: there is strong cosmological and astrophysical evidence for the existence of dark matter ( dm ) in the universe .
the observations indicate that dm , about 26% of the total mass - energy of the universe , is non - baryonic , non - relativistic and not subject to electromagnetic interactions @xcite . in the framework of the weakly interacting massive particles ( wimps ) paradigm ,
the visible baryonic part of a galaxy is embedded in the dm halo . in the most common scenario.
Please generate the next two sentences of the article | , wimps can scatter elastically with matter and become trapped in massive astrophysical objects such as the sun@xcite .
there , dm particles could self - annihilate , reaching equilibrium between capture and annihilation rates over the age of the solar system . |
7,144 | Suppose that you have an abstract for a scientific paper: we consider a mechanism by which dyons ( electrically charged magnetic monopoles ) can produce both a @xmath0- and @xmath1-odd ( i.e. time reversal invariance and parity violating ) mixed polarizability @xmath2 [ defined by @xmath3 , where @xmath4 is the energy change when electric ( @xmath5 ) and magnetic ( @xmath6 ) fields are applied to a system ] and a @xmath0- and @xmath1-odd interaction between two particles : @xmath7 , where the @xmath8 are electron and quark spinors .
the latter can create atomic and neutron electric dipole moments ( edms ) . from experimental bounds on these
we find limits on the properties of dyons .
our best limit , using the experimental limit for the edm of the tl atom , is @xmath9 , where @xmath10 is the dyon mass and @xmath11 is the electric and @xmath12 the magnetic charge of the dyons .
the contribution of dyons to @xmath13 violation in k - meson decays is also estimated . .
And you have already written the first three sentences of the full article: it would be very interesting if @xmath13 and @xmath0 violation were a consequence of another fundamental symmetry , such as a symmetry between electric and magnetic charges . in ref .
@xcite we considered the possibility that dyons ( electrically charged magnetic monopoles ) could induce parity and time invariance violating electric dipole moments ( edms ) of quantum systems .
the point is that the polarization of the dyon vacuum by the coulomb field may produce not only the usual correction to the electric field , @xmath14 , but also a radial magnetic field @xmath15 , where @xmath11 is the electric and @xmath12 the magnetic charge of the dyons ( the corresponding antidyons would have charges @xmath16 and @xmath17 ) ..
Please generate the next two sentences of the article | the interaction of electrons ( or quarks ) with this magnetic field could generate atomic ( and neutron ) electric dipole moments .
[ in addition , electron and neutron edms @xmath18 could appear due to higher order diagrams ( @xmath19 is the electron or quark mass ; @xmath10 is the dyon mass ) . ] |
7,145 | Suppose that you have an abstract for a scientific paper: we discuss the quantum phases and their diffusion in a spinor-1 atomic bose - einstein condensate . for ferromagnetic interactions ,
we obtain the exact ground state distribution of the phase fluctuations corresponding to the total atom number ( @xmath0 ) , the magnetization ( @xmath1 ) , and the alignment ( or hypercharge ) ( @xmath2 ) of the system .
the mean field ground state is shown to be stable against these fluctuations , which dynamically recover the two continuous symmetries associated with the conservation of @xmath0 and @xmath1 as in current experiments .
since the observation of bose - einstein condensation of trapped atomic clouds @xcite , the coherence properties of the condensate has become the focus of many theoretical studies @xcite . within the mean - field theory ,
it is commonly assumed that the condensate can be described by a @xmath3 symmetry breaking field @xcite , equivalent to a coherent state assumption of the ground state .
( see refs .
@xcite for discussions of @xmath3-symmetric approaches ) .
although quite successful in providing theoretical understanding to many experimental observations , such a coherent state assumption is not necessarily consistent with real experimental situations , where the fluctuations of the atom numbers are difficult to control @xcite .
a coherent state leads to a poisson distribution of atoms . for a ground state with average of @xmath0 atoms ,
the associated number fluctuations are of the order @xmath4 . as was initially pointed out in refs .
@xcite , this number fluctuation of a coherent state condensate leads to the diffusion " ( or spreading ) of its initial phase . in a scalar condensate
, this diffusion , a dynamic attempt to restore the @xmath3 symmetry of the interacting atomic system , can be studied in terms of a zero mode , or the goldstone mode of the condensate @xcite .
more physically meaningful discussions in terms of the relative phase of two condensates were studied soon afterwards @xcite . experimentally....
And you have already written the first three sentences of the full article: the coefficients in the zero mode hamiltonian ( [ hzero ] ) are @xmath148\big],\nonumber\\ b&=&\frac{1}{2n_0 ^ 2}\left[\varepsilon(1+m^2 ) -8c_2{\cal o}_{\phi\theta}m^2\right]\nonumber\\ c&=&\frac{1}{3n_0 ^ 2}(\varepsilon-4c_2{\cal o}_{\phi\theta}),\nonumber\\ \alpha&=&\frac{\sqrt{2}}{6n_0 ^ 2}(1 + 3m^2 ) ( \varepsilon-4c_2{\cal o}_{\phi\theta}),\nonumber\\ \beta&=&-\frac{2m}{\sqrt{3}n_0 ^ 2}(\varepsilon -4c_2{\cal o}_{\phi\theta}),\nonumber\\ \gamma&=&-\frac{2m}{n_0 ^ 2}\sqrt{\frac{2}{3}}\left [ \varepsilon - c_2{\cal o}_{\phi\theta}(1 + 3m^2)\right],\nonumber\\ \eta&=&-3c_2n_0 ^ 2{\cal o}_{\phi\phi}/\hbar^2.\nonumber\end{aligned}\ ] ].
Please generate the next two sentences of the article | |
7,146 | Suppose that you have an abstract for a scientific paper: in this paper , we address strongly convex programming for principal component pursuit with reduced linear measurements , which decomposes a superposition of a low - rank matrix and a sparse matrix from a small set of linear measurements .
we first provide sufficient conditions under which the strongly convex models lead to the exact low - rank and sparse matrix recovery ; second , we also give suggestions on how to choose suitable parameters in practical algorithms .
qingshan you and qun wan yipeng liu ( communicated by the associate editor name ) .
And you have already written the first three sentences of the full article: recently , much attention has been drawn to the problem of recovering a target matrix from a small set of linear measurements .
the estimated matrix is a superposition of low - complexity structure .
it can be found in many different fields , such as medical imaging @xcite , seismology @xcite , information retrieval @xcite and machine learning @xcite ..
Please generate the next two sentences of the article | this problem regained great attention after the publication of the pioneering works of e.j .
cands et al @xcite . |
7,147 | Suppose that you have an abstract for a scientific paper: supernova ( sn ) 2006gy was a hydrogen - rich core - collapse sn that remains one of the most luminous optical supernovae ever observed .
the total energy budget ( @xmath0 2@xmath110@xmath2 erg radiated in the optical alone ) poses many challenges for standard sn theory .
we present new ground - based near - infrared ( nir ) observations of , as well as a single epoch of _
hubble space telescope ( hst ) _ imaging obtained more than two years after the explosion .
our nir data taken around peak optical emission show an evolution that is largely consistent with a cooling blackbody , with tentative evidence for a growing nir excess starting at day @xmath3100 .
our late - time keck adaptive optics ( ao ) nir image , taken on day 736 , shows little change from previous nir observations taken around day 400 .
furthermore , the optical _ hst _ observations show a reduced decline rate after day 400 , and the sn is bluer on day 825 than it was at peak .
this late - time decline is inconsistent with @xmath4co decay , and thus is problematic for the various pair - instability sn models used to explain the nature of .
the slow decline of the nir emission can be explained with a light echo , and we confirm that the late - time nir excess is the result of a massive ( @xmath510 ) dusty shell heated by the sn peak luminosity .
the late - time optical observations require the existence of a scattered light echo , which may be generated by the same dust that contributes to the nir echo .
both the nir and optical echoes originate in the proximity of the progenitor , @xmath310@xmath6 cm for the nir echo and @xmath720 pc for the optical echo , which provides further evidence that the progenitor of was a very massive star . .
And you have already written the first three sentences of the full article: at the time of discovery , supernova ( sn ) 2006gy was the most luminous sn ever found @xcite
. generated a great deal of interest ; in addition to being @xmath3100 times more luminous than a typical type ii ( hydrogen - rich , core - collapse ) sn at peak , it exhibited a long rise time ( @xmath370 day ) and slow decline , leading to speculation that it may have been the first observed example of a pair - instability sn ( @xcite ) or a pulsational pair - instability sn @xcite .
was classified as a type iin sn ( see @xcite for a definition of the type iin subclass and @xcite for a review of its spectral properties ) based on the relatively narrow emission features present in the early - time sn spectrum @xcite . some type iin supernovae ( sne iin ) are known to be overluminous relative to their typical sn ii counterparts , probably due to the collision of fast - moving sn ejecta and a dense , possibly clumpy , circumstellar medium ( csm ; @xcite ) . in a companion paper @xcite , a detailed spectroscopic comparison of is made to other sne iin ..
Please generate the next two sentences of the article | is unique within the sn iin subclass , however , because typical interaction models can not explain its early - time behavior , suggesting the need for alternative models for this particular object @xcite .
pair - instability sne @xcite are expected to occur in very massive , low - metallicity stars , such as those that may have been present in the metal - free environment of the very early universe ( e.g. , @xcite ) . |
7,148 | Suppose that you have an abstract for a scientific paper: in this paper , we study partitions of positive integers into distinct quasifibonacci numbers .
a digraph and poset structure is constructed on the set of such partitions .
furthermore , we discuss the symmetric and recursive relations between these posets .
finally , we prove a strong generalization of robbins result on the coefficients of a quasifibonacci power series . .
And you have already written the first three sentences of the full article: let @xmath0 denote the fibonacci numbers ( where we have shifted the usual initial condition ) ; i.e. @xmath1 .
+ consider the formal power series @xmath2 let @xmath3 be the coefficient of @xmath4 in @xmath5 .
it is clear that @xmath6 , where @xmath7 is the number of partitions of @xmath8 into an even number of distinct fibonacci numbers , and @xmath9 is the number of partitions of @xmath8 into an odd number of distinct fibonacci numbers . in [ 2 ] , n. robbins proved that @xmath10 . in [ 1 ].
Please generate the next two sentences of the article | , f. ardila gave a simpler proof for robbins result by giving a recursion on @xmath3 .
in this paper , we consider _ quasifibonacci numbers _ , which serve as generalization of fibonacci numbers |
7,149 | Suppose that you have an abstract for a scientific paper: we report the discovery of variability in the x - ray emission from the wolf - rayet type star wr65 . using archival data spanning over 5yr
we detect changes of the x - ray flux by a factor of 3 accompanied by changes in the x - ray spectra .
we believe that this x - ray emission originates from wind - wind collision in a massive binary system .
the observed changes can be explained by the variations in the emission measure of the hot plasma , and by the different absorption column along the binary orbit .
the x - ray spectra of display prominent emission features at wavelengths corresponding to the lines of strongly ionized fe , ca , ar , s , si , and mg .
wr65 is a carbon rich wc9d star that is a persistent dust maker .
this is the first investigation of any x - ray spectrum for a star of this spectral type .
there are indications that the dust and the complex geometry of the colliding wind region are pivotal in explaining the x - ray properties of .
[ firstpage ] stars : early - type stars : wolf - rayet stars : individual : wr65 x - ray : stars .
And you have already written the first three sentences of the full article: more than 54% of all wolf - rayet ( wr ) stars are in binary systems that consist of a wr and an ob - type star @xcite .
the collision between two stellar winds in these systems produces characteristic signatures in different wavelength bands that can include non - thermal radio emission @xcite , copious and variable x - rays @xcite , and dust emission in the infrared ( ir ) @xcite .
subject of this _ letter _ is the wc9d star wr65 ..
Please generate the next two sentences of the article | @xcite reported the presence of warm dust in this object .
they discussed that in early - type wc stars an increase in the wind density provided by e.g. shock compression in colliding winds in binary systems may be sufficient to result in grain formation . |
7,150 | Suppose that you have an abstract for a scientific paper: we study the refractive - index sensing properties of plasmonic nanotubes with a dielectric core and ultra - thin metal shell .
the few - nm thin metal shell is described by both the usual drude model and the nonlocal hydrodynamic model to investigate the effects of nonlocality .
we derive an analytical expression for the extinction cross section and show how sensing of the refractive index of the surrounding medium and the figure - of - merit are affected by the shape and size of the nanotubes .
comparison with other localized surface plasmon resonance sensors reveals that the nanotube exhibits superior sensitivity and comparable figure - of - merit .
example.eps gsave newpath 20 20 moveto 20 220 lineto 220 220 lineto 220 20 lineto closepath 2 setlinewidth gsave .4 setgray fill grestore stroke grestore .
And you have already written the first three sentences of the full article: it is well known that metallic nanoparticles can sustain localized surface plasmon ( lsp ) oscillations , whose resonance frequencies in the quasi - static limit depend solely on the geometry of the nanoparticle , the permittivity of the metal and the surrounding permittivity .
the dependency of the lsp resonance ( lspr ) on the surrounding medium makes metallic particles extremely good sensors , progressing towards the detection of single molecules @xcite .
however , the weak effect of retardation on the lsp resonance in nanosized metal particles leaves only one parameter to truly engineer : the geometry . by modifying the structure of the metal nanoparticle to have a dielectric core with a metal shell.
Please generate the next two sentences of the article | , an increased tunability is achieved due to the plasmon hybridization of the inner and outer surfaces of the metal @xcite .
especially the spherical core - shell structure has received a considerable amount of attention in recent years @xcite due to its excellent and tunable sensing properties , which show great promise in biological studies such as cancer therapy @xcite . |
7,151 | Suppose that you have an abstract for a scientific paper: we consider the asymptotic - safety scenario for quantum gravity which constructs a non - perturbatively renormalisable quantum gravity theory with the help of the functional renormalisation group .
we verify the existence of a non - gauian fixed point and include a running curvature - ghost coupling as a first step towards the flow of the ghost sector of the theory .
we find that the scalar curvature - ghost coupling is asymptotically free and rg relevant in the ultraviolet .
most importantly , the property of asymptotic safety discovered so far within the einstein - hilbert truncation and beyond remains stable under the inclusion of the ghost flow . .
And you have already written the first three sentences of the full article: the construction of an internally consistent and falsifiable theory of quantum gravity is one of the major challenges of modern theoretical physics . as the perturbative quantisation of the einstein - hilbert action yields a non - renormalisable theory @xcite several alternative approaches
have been proposed : a change in the degrees of freedom and of the microscopic action , as well as a different approach to quantisation , or assumptions about a discrete nature of spacetime offer possible routes to a predictive theory of quantum gravity .
however , the possibility remains that the apparent nonrenormalisability is not a failure of einstein gravity but rather of the simple perturbative quantisation scheme ..
Please generate the next two sentences of the article | this is the underlying viewpoint of , e.g. , lattice simulations of the gravitational path integral @xcite . within analytical continuum approaches to a non - perturbative quantisation of gravity , weinberg s asymptotic - safety scenario @xcite represents a possible way for a predictive theory of quantum gravity :
weinberg argued that , if the non - perturbative renormalisation group trajectory of a quantum field theory approaches a non - gauian fixed point ( ngfp ) in the ultraviolet ( uv ) , the uv limit can safely be taken . |
7,152 | Suppose that you have an abstract for a scientific paper: a method to avoid the explicit time integration of small dust grains in the two fluid gas /dust smoothed particle hydrodynamics ( sph ) approach is proposed . by assuming a very simple exponential decay model for the relative velocity between the gas and dust components , all the effective characteristics of the drag force can be reproduced .
a series of tests has been performed to compare the accuracy of the method with analytical and explicit integration results .
we find that the method performs well on a wide range of tests , and can provide large speed ups over explicit integration when the dust stopping time is small .
we have also found that the method is much less dissipative than conventional explicit or implicit two - fluid sph approaches when modelling dusty shocks .
[ firstpage ] hydrodynamics - methods : numerical - planets and satellites : formation - protoplanetary discs - dust , extinction . .
And you have already written the first three sentences of the full article: gas and dust mixtures are ubiquitously present in nature , so a correct numerical prescription of its evolution turns out to be of the uttermost importance . in many astrophysical applications
, dust can be described as a set of particles immersed in a fluid phase ( gas ) .
mathematically , such a system can be described using the @xcite notation , by the following set of equations @xmath0.
Please generate the next two sentences of the article | @xmath1 @xmath2 @xmath3 @xmath4 where @xmath5 and @xmath6 are the dust particles number density and mass respectively , @xmath7 is the gas density , @xmath8 and @xmath9 are the dust and gas velocities , @xmath10 is the gas thermal energy , @xmath11 is the drag coefficient for a single particle , @xmath12 represents the gas pressure , and @xmath13 stands for any external forces , like gravity or radiation pressure . note than in equation [ eu2 ] , the external force per unit volume @xmath14 is required for the gas .
@xmath15 is the lagrangian derivative , and its specific form will be discussed in section 2 . |
7,153 | Suppose that you have an abstract for a scientific paper: based on the ideas of cyclotomic cosets , idempotents and mattson - solomon polynomials , we present a new method to construct gf(@xmath0 ) , where @xmath1 cyclic low - density parity - check codes .
the construction method produces the dual code idempotent which is used to define the parity - check matrix of the low - density parity - check code . an interesting feature of this construction method is the ability to increment the code dimension by adding more idempotents and so steadily decrease the sparseness of the parity - check matrix .
we show that the constructed codes can achieve performance very close to the sphere - packing - bound constrained for binary transmission .
coding , idempotent , non binary ldpc , mattson - solomon polynomial .
And you have already written the first three sentences of the full article: since the recent rediscovery of low - density parity - check ( ldpc ) codes , a great deal of effort has been devoted to constructing ldpc codes that can work well with the belief - propagation iterative decoder .
the studies of long block - length ldpc codes are very much established .
the recent works of @xcite , @xcite have shown that , for long block - lengths , the best performing ldpc codes are irregular codes and these codes can outperform turbo codes of the same block - length and code - rate ..
Please generate the next two sentences of the article | these long ldpc codes have degree distributions which are derived from differential evolution @xcite or gaussian approximation @xcite .
it can be shown that , using the concentration theorem @xcite , the performance of infinitely long ldpc codes of a given degree distribution can be characterised by the average performance of the ensemble based on cycle - free assumption . |
7,154 | Suppose that you have an abstract for a scientific paper: in this paper we generalize the local removable singularity theorem in @xcite for minimal laminations to the case of weak @xmath0-laminations ( with @xmath1 constant ) in a punctured ball of a riemannian three - manifold .
we also obtain a curvature estimate for any weak cmc foliation ( with possibly varying constant mean curvature from leaf to leaf ) of a compact riemannian three - manifold @xmath2 with boundary solely in terms of a bound of the absolute sectional curvature of @xmath2 and of the distance to the boundary of @xmath2 .
we then apply these results to classify weak cmc foliations of @xmath3 and @xmath4 with a closed countable set of singularities .
_ mathematics subject classification : _
primary 53a10 , secondary 49q05 , 53c42 _ key words and phrases : _ minimal surface , @xmath0-surface , stability , curvature estimates , finite total curvature , minimal lamination , weak @xmath0-lamination , weak cmc foliation , removable singularity .
the classification of cmc foliations of @xmath3 and @xmath5 with countably many singularities .2 in william h. meeks iii joaqun p ' erez antonio ros .
And you have already written the first three sentences of the full article: in this paper , we address a number of outstanding classical questions on the geometry of embedded surfaces of constant mean curvature and more generally , laminations and foliations of @xmath3 and other three - manifolds , where the leaves of these laminations are surfaces with constant mean curvature ( possibly varying from leaf to leaf ) . in the foliation case , we call every such foliation a _ cmc foliation . _
the first of these classical problems is to classify codimension one cmc foliations of @xmath3 or @xmath4 ( with their standard metrics ) in the complement of a closed countable set @xmath6 .
the simplest such examples in @xmath3 are families of parallel planes or concentric spheres around a given point ..
Please generate the next two sentences of the article | a slightly more complicated example appears when considering a family of pairwise disjoint planes and spheres as in figure [ figspheres ] , where the set @xmath6 consists of two points . by spheres and planes with two singularities .
, width=453 ] we solve this classification problem in complete generality ( see theorem [ thmspheres ] for a solution of an even more general problem , where the leaves of the `` foliation '' are allowed to intersect in a controlled manner . ] ) : [ thmspheresintrod ] suppose @xmath7 is a cmc foliation of @xmath8 with a closed countable set @xmath9 of singularities is a foliation of @xmath10 , and it does not extend to a cmc foliation of @xmath11 for any proper closed subset @xmath12 . |
7,155 | Suppose that you have an abstract for a scientific paper: we classify the unimodular equivalence classes of inclusion - minimal polygons with a certain fixed lattice width . as a corollary
, we find a sharp upper bound on the number of lattice points of these minimal polygons .
+ _ msc2010 : _ primary 52b20 , 52c05 , secondary 05e18 .
And you have already written the first three sentences of the full article: let @xmath0 be a non - empty _ lattice polygon _ ,
i.e. the convex hull of a finite number of lattice points in @xmath1 , and consider a _ lattice direction _ @xmath2 , i.e. a non - zero primitive vector . the _ lattice width of @xmath3 in the direction @xmath4 _ is @xmath5 the _ lattice width _ of @xmath3 is defined as @xmath6 . throughout this paper
we will assume that @xmath3 is two - dimensional , hence @xmath7 ..
Please generate the next two sentences of the article | a lattice direction @xmath4 that satisfies @xmath8 is called a _ lattice width direction _ of @xmath3 .
two lattice polygons @xmath3 and @xmath9 are called _ ( unimodularly ) equivalent _ if and only if there exists a _ unimodular transformation _ |
7,156 | Suppose that you have an abstract for a scientific paper: this article proposes an emotive lifelike robotic face , called expressionbot , that is designed to support verbal and non - verbal communication between the robot and humans , with the goal of closely modeling the dynamics of natural face - to - face communication .
the proposed robotic head consists of two major components : 1 ) a hardware component that contains a small projector , a fish - eye lens , a custom - designed mask and a neck system with 3 degrees of freedom ; 2 ) a facial animation system , projected onto the robotic mask , that is capable of presenting facial expressions , realistic eye movement , and accurate visual speech .
we present three studies that compare human - robot interaction with human - computer interaction with a screen - based model of the avatar .
the studies indicate that the robotic face is well accepted by users , with some advantages in recognition of facial expression and mutual eye gaze contact . .
And you have already written the first three sentences of the full article: although robots are finding their place in our society as artificial pets , entertainers , and tools for therapists , current technologies have yet to reach the full emotional and social capabilities necessary for rich and robust interaction with human beings . to achieve this potential
, research must imbue robots with the emotional and social capabilities -both verbal and non - verbal- necessary for rich and robust interaction with human beings .
this article describes research in which robotic heads can model natural face - to - face communication with individuals ..
Please generate the next two sentences of the article | human face - to - face communication is based on multiple communication channels including auditory and visual .
facial expressions and gaze direction are the most important visual channels in human face - to - face communication . these channels of communications are considered in our research . despite significant progress towards development of realistic robotic heads , |
7,157 | Suppose that you have an abstract for a scientific paper: we extend the post - processing finite - size ( fs ) correction method , developed by kwee , zhang , and krakauer [ _ phys .
rev .
lett . _ * 100 * , 126404 ( 2008 ) ] , to spin polarized systems .
the method estimates the fs effects in many - body electronic structure calculations of extended systems by a modified density functional theory ( dft ) calculation , without having to repeat expensive many - body simulations .
we construct a unified fs dft exchange - correlation functional for spin unpolarized and fully spin polarized systems , under the local density approximation .
the results are then interpolated to arbitrary spin polarizations .
generalization to other functional forms in dft are discussed .
the application of this fs correction method to several typical magnetic systems with varying supercell sizes demonstrates that it consistently removes most of the fs errors , leading to rapid convergence of the many - body results to the infinite size limit . .
And you have already written the first three sentences of the full article: many - body simulation methods , such as diffusion monte carlo ( dmc ) @xcite and auxiliary field quantum monte carlo ( afqmc ) , @xcite are capable of yielding highly accurate results for electronic systems . in extended systems , however , because of the use of periodic boundary conditions ( pbc ) , finite - size ( fs ) errors arise in many - body ( mb ) calculations , which are often larger than the statistical and other systematic errors .
the fs error reflects the spurious interactions of the system , modeled by a finite - size simulation cell ( supercell ) , with its own periodic images .
the long - range nature of the coulomb interaction in electronic systems exacerbates the problem , and makes the fs error more pronounced . to reduce this error.
Please generate the next two sentences of the article | , calculations have to be performed using larger and larger simulation cells , in order to extrapolate the results to the infinite limit of the supercell size .
the computational cost of mb calculations is typically high . |
7,158 | Suppose that you have an abstract for a scientific paper: the debye and meissner screening masses of the gluons and the photon in neutral and @xmath0-equilibrated dense two - flavor quark matter are calculated .
the results are presented in a general form that can be used in gapped as well as gapless color superconducting phases .
the results for the magnetic screening masses indicate that the system develops a chromomagnetic instability .
possible consequences of the instability are discussed . .
And you have already written the first three sentences of the full article: from the time when the quarks were predicted @xcite , their nature has remained rather elusive .
the reason is that direct experimental studies of quarks are very limited .
quarks do not exist in vacuum as free particles . under normal conditions ,.
Please generate the next two sentences of the article | they are always confined inside hadrons .
the underlying theory of strong interactions quantum chromodynamics ( qcd ) predicts that quarks should become deconfined at very high temperatures and/or very high densities @xcite . |
7,159 | Suppose that you have an abstract for a scientific paper: we investigate three - dimensional rolled - up metamaterials containing optically active quantum wells and metal gratings supporting surface plasmon polarition resonances .
finite - difference time - domain simulations show that by matching the surface plasmon polarition resonance with the active wavelength regime of the quantum well a strong transmission enhancement is observed when illuminating the sample with p - polarized radiation .
this transmission enhancement is further increased by taking advantage of the fabry - perot resonances of the structure . .
And you have already written the first three sentences of the full article: the emerging field of metamaterials and the realization of materials exhibiting a negative index of refraction ( nim ) in the past ten years opened the way for various fascinating applications . with these novel materials physical applications like cloaking devices @xcite and optical imaging beyond the diffraction limit
@xcite have become possible .
a metamaterial consists of artificial structures which are much smaller than the wavelength of the operating incident radiation ..
Please generate the next two sentences of the article | nims have been realized by metal - dielectric structures e.g. split - ring resonators deposited on dielectrics @xcite or fishnet structures @xcite .
however , due to the electron - beam lithography fabrication process of these structures , the realization of three - dimensional metamaterials requires a sequentially stacking of single layers @xcite . |
7,160 | Suppose that you have an abstract for a scientific paper: we present a microscopic theory for thermally driven transport in colloidal suspension of charged particles . for small valency ,
we recover known results from debye - hckel approximation , which are in quantitative agreement with recent experiments on polystyrene particles and sodium dodecyl sulphate micelles .
significant modifications occur for strong charges , where the thermodiffusion coefficient is independent of the debye length and the permittivity of the electrolyte , but is proportional to the valency of the macroion . .
And you have already written the first three sentences of the full article: a thermally driven flow , or ludwig - soret effect , is observed when applying a thermal gradient to a complex fluid @xcite .
the corresponding mass transport is relevant for natural and technological processes , such as the global circulation of sea water @xcite and the phase behavior of eutectic systems at solidification @xcite . in recent years
, detailed experimental studies on macromolecular solutions and colloidal suspensions have revealed unambiguous and often surprising dependencies of the soret effect on system parameters such as salinity , surface coating , solute concentration , and molecular weight rau02,rau05,wie04,kit04,bra02,zha99,deg03,iac03,pia02,dem04,duh05,duh06 ..
Please generate the next two sentences of the article | although the analogy to electrophoresis indicates the relevance of surface or marangoni forces and suggests a hydrodynamic treatment @xcite , the physcial mechanisms that drive thermophoresis in liquids are poorly understood and differ from those in gaseous phases @xcite .
diffusion theory accounts for the particle current due to density gradient in terms of fick s law @xmath0 , where @xmath1 is the number of suspended particles per unit volume . for a closed system |
7,161 | Suppose that you have an abstract for a scientific paper: we present numerical results obtained on the cemracs project predictive sms proposed by safety line .
the goal of this work was to elaborate a purely statistical method in order to reconstruct the deceleration profile of a plane during landing under normal operating conditions , from a database containing around @xmath0 recordings .
the aim of safety line is to use this model to detect malfunctions of the braking system of the plane from deviations of the measured deceleration profile of the plane to the one predicted by the model .
this yields to a multivariate nonparametric regression problem , which we chose to tackle using a bayesian approach based on the use of gaussian processes similar to the one presented in @xcite .
we also compare this approach with other statistical methods .
nous prsentons des rsultats numriques obtenus sur le projet cemracs predictive sms propos par safety line .
lobjectif de ce travail tait dlaborer une mthode purement statistique afin de reconstruire le profil de dclration dun avion durant son atterissage , partir dune base de donnes contenant peu prs @xmath0 enregistrements .
le but de safety line est dutiliser ce modle pour dtecter des anomalies du systme de freinage de lavion partir de lcart entre le profil de dclration de lavion mesur et celui prdit par le modle .
ceci mne un problme de rgression multivari non paramtrique que nous avons choisi de traiter via une approche baysienne utilisant des processus gaussiens similaire celle prsente dans @xcite .
nous comparons galement cette approche avec dautres mthodes statistiques classiques . .
And you have already written the first three sentences of the full article: safety line is a company that offers innovative solutions ( software and statistical analysis ) for risk management in the field of air transport ( airlines , maintenance organizations , airports ... ) .
the main expertise of safety line relies in hazard identification and risk assessment , assurance and safety promotion .
+ the objective of safety line for this cemracs project is to improve its technical modeling of plane systems . to monitor the proper functioning of a given system ,.
Please generate the next two sentences of the article | their overall approach is to follow the time evolution of an indicator of the state of the system and detect deviations from the expected behaviour , which could be indicative of a malfunction . for this ,
the main challenge is to estimate as precisely as possible and at any time the value of this indicator in normal operating conditions . |
7,162 | Suppose that you have an abstract for a scientific paper: we have identified galaxies near two quasars which are at the redshift of damped lyman-@xmath0 ( dla ) systems in the uv spectra of the quasars .
both galaxies are actively forming stars .
one galaxy has a luminosity close to the break in the local galaxy luminosity function , @xmath1 , the other is significantly fainter than @xmath1 and appears to be interacting with a nearby companion . despite the strong selection effects favoring spectroscopic identification of the most luminous dla galaxies , many of the spectroscopically - identified dla galaxies in the literature are sub-@xmath1 , suggesting that the majority of the dla population is probably sub-@xmath1 , in contrast to mgii absorbers at similar redshifts whose mean luminosity is close to @xmath1 . .
And you have already written the first three sentences of the full article: damped ly@xmath0 ( dla ) absorbers in quasar spectra are the class of absorbers with the highest column density of neutral hydrogen ( @xmath2 ) .
they are important as it can be shown that they contain the bulk of the neutral hydrogen content of the universe ( e.g. storrie - lombardi & wolfe 2000 ) .
the similarity of the column densities of dlas to those through the disks of spiral galaxies have lead some authors to consider them as the direct progenitors of present - day spirals ( e.g. prochaska & wolfe 1998 ) ..
Please generate the next two sentences of the article | however , dwarf galaxies and low surface brightness galaxies ( lsbgs ) also can have similar columns ( boissier , peroux & pettini 2003 ) , and metallicity arguments support dwarf galaxies ( pettini et al .
theorists have interpreted them in the context of hierarchical galaxy formation models as sub - units which will eventually merge to form @xmath1 galaxies today ( haehnelt , steinmetz & rauch 1998 ; maller et al . 2001 ) or as dwarf galaxies in which star formation is supressed by supernova feedback ( efstathiou 2000 ) . |
7,163 | Suppose that you have an abstract for a scientific paper: we study abelian dominance and monopole condensation for the quark confinement physics using the lattice qcd simulations in the ma gauge .
these phenomena are closely related to the dual superconductor picture of the qcd vacuum , and enable us to construct the dual ginzburg - landau ( dgl ) theory as an useful effective theory of nonperturbative qcd .
we then apply the dgl theory to the studies of the low - lying hadron structure and the scalar glueball properties .
# 1#2#3#4#1 * # 2 * , # 3 ( # 4 ) .
And you have already written the first three sentences of the full article: recent studies of the lattice qcd in the maximally abelian ( ma ) gauge suggest the remarkable properties of the qcd vacuum , such as abelian dominance@xcite and monopole condensation@xcite , which provide the dual superconductor picture of the qcd vacuum as is described by the dual ginzburg - landau ( dgl ) theory@xcite . in the ma gauge
, qcd is reduced into an abelian gauge theory including color - magnetic monopoles . according to the lattice
qcd results , the nonperturbative quantities as the string tension and the chiral condensate are almost reproduced only by the diagonal gluon part , while the off - diagonal gluon does not contribute to such the long - range physics , namely , abelian dominance ..
Please generate the next two sentences of the article | furthermore , the world - line of the color - magnetic monopole in the confinement phase appears as the global network , which indicates monopole condensation .
then , the dgl theory can be constructed by extracting the diagonal gluon as the relevant degrees of freedom and taking into account monopole condensation . |
7,164 | Suppose that you have an abstract for a scientific paper: microtubules are highly regulated dynamic elements of the cytoskeleton of eukaryotic cells .
one of the regulation mechanisms observed in living cells is the severing by the proteins katanin and spastin .
we introduce a model for the dynamics of microtubules in the presence of randomly occurring severing events . under the biologically motivated assumption that the newly created plus end undergoes a catastrophe
, we investigate the steady state length distribution .
we show that the presence of severing does not affect the number of microtubules , regardless of the distribution of severing events . in the special case in which the microtubules can not recover from the depolymerizing state ( no rescue events ) we derive an analytical expression for the length distribution . in the general case
we transform the problem into a single ode that is solved numerically . .
And you have already written the first three sentences of the full article: microtubules are filamentous protein aggregates that appear in all eukaryotic cells .
they have an inherent polarity that results in different dynamics at their two ends .
the so - called plus end is highly dynamic , alternating between prolonged periods of polymerization ( growth ) and depolymerization ( shrinkage ) @xcite . on the other end of the filament ,.
Please generate the next two sentences of the article | the minus end often remains connected to the locus of nucleation @xcite or is found to exhibit relatively steady depolymerization @xcite .
the combination of slow depolymerization at the minus end and prolonged growth at the plus end leads to a phenomenon known as treadmilling , whereby the individual tubulin dimers appear to move from the plus to the minus end @xcite . as the stiffest of the cytoskeletal filaments , microtubules |
7,165 | Suppose that you have an abstract for a scientific paper: using a markov chain monte carlo optimization algorithm and a computer simulation , i find the passenger ordering which minimizes the time required to board the passengers onto an airplane .
the model that i employ assumes that the time that a passenger requires to load his or her luggage is the dominant contribution to the time needed to completely fill the aircraft .
the optimal boarding strategy may reduce the time required to board and airplane by over a factor of four and possibly more depending upon the dimensions of the aircraft .
in addition , knowledge of the optimal boarding procedure can inform decisions regarding changes to methods that are employed by a particular carrier .
i explore some of the salient features of the optimal boarding method and discuss practical modifications to the optimal .
finally , i mention some of the benefits that could come from implementing an improved passenger boarding scheme . .
And you have already written the first three sentences of the full article: several passenger boarding schemes are used by the airline industry in effort to quickly load passengers and their luggage onto an airplane .
since the passenger boarding time often takes longer than refueling and restocking the airplane its reduction could constitute a significant savings to a particular carrier , especially for airplanes which make several trips in a day .
conventional wisdom would suggest that boarding from the front to the back is the worst case but that boarding from the back to the front is optimal or nearly so . indeed , this is the strategy that is often employed , boarding passengers in blocks from the rear of the plane to the front . in this case ,.
Please generate the next two sentences of the article | conventional wisdom only provides an answer that is half right .
the worst boarding method is , indeed , to board the plane from front to back . |
7,166 | Suppose that you have an abstract for a scientific paper: compact astrophysical objects that rotate rapidly may encounter the dynamical `` bar instability . ''
the bar - like deformation induced by this rotational instability causes the object to become a potentially strong source of gravitational radiation .
we have carried out a set of long - duration simulations of the bar instability with two eulerian hydrodynamics codes .
our results indicate that the remnant of this instability is a persistent bar - like structure that emits a long - lived gravitational radiation signal . .
And you have already written the first three sentences of the full article: the direct detection of gravitational radiation presents one of the greatest scientific challenges of our day . with interferometers such as ligo , virgo , geo , and tama @xcite expected to be operating in the next few years , and
a new generation of spherical resonant mass detectors under study @xcite , the calculation of the signals expected from various astrophysical sources has a high priority .
accurate calculations of the waveforms are needed to enable both the detection and identification of sources @xcite ..
Please generate the next two sentences of the article | in particular , short duration bursts are expected to be more difficult to detect than longer - lived signals .
one interesting class of sources includes rapidly rotating compact objects that develop the rotationally - induced `` bar instability '' . |
7,167 | Suppose that you have an abstract for a scientific paper: as improved versions of successive cancellation ( sc ) decoding algorithm , successive cancellation list ( scl ) decoding and successive cancellation stack ( scs ) decoding are used to improve the finite - length performance of polar codes .
unified descriptions of sc , scl and scs decoding algorithms are given as path searching procedures on the code tree of polar codes .
combining the ideas of scl and scs , a new decoding algorithm named successive cancellation hybrid ( sch ) is proposed , which can achieve a better trade - off between computational complexity and space complexity .
further , to reduce the complexity , a pruning technique is proposed to avoid unnecessary path searching operations .
performance and complexity analysis based on simulations show that , with proper configurations , all the three improved successive cancellation ( isc ) decoding algorithms can have a performance very close to that of maximum - likelihood ( ml ) decoding with acceptable complexity .
moreover , with the help of the proposed pruning technique , the complexities of isc decoders can be very close to that of sc decoder in the moderate and high signal - to - noise ratio ( snr ) regime .
polar codes , successive cancellation decoding , code tree , tree pruning . .
And you have already written the first three sentences of the full article: codes , proposed by arikan @xcite , are proved to achieve the symmetric capacities of the binary - input discrete memoryless channels ( b - dmcs ) .
this capacity - achieving code family is based on a technique called channel polarization . by performing the channel splitting and channel combining operations on independent copies of a given b - dmc ,
a set of synthesized binary - input channels can be obtained ..
Please generate the next two sentences of the article | let @xmath0 denote the symmetric capacity of a b - dmc @xmath1 .
it is proved in @xcite that : with @xmath2 uses of @xmath1 , @xmath3 , when @xmath4 is large enough , it is possible to construct @xmath4 synthesized channels such that @xmath5 of them are completely unreliable and @xmath6 of them are noiseless . by transmitting free bits ( called information bits ) over the noiseless channels and transmitting a sequence of fixed bits ( called frozen bits ) over the others , polar codes can achieve the symmetric capacity under a successive cancellation ( sc ) decoder with both encoding and decoding complexity @xmath7 . in @xcite , it is proved that the block error probability of polar code under sc decoding satisfies @xmath8 for any @xmath9 when code length @xmath4 is large enough and code rate @xmath10 . |
7,168 | Suppose that you have an abstract for a scientific paper: the notion of a qubit is ubiquitous in quantum information processing . in spite of the simple abstract definition of qubits as two - state quantum systems ,
identifying qubits in physical systems is often unexpectedly difficult .
there are an astonishing variety of ways in which qubits can emerge from devices .
what essential features are required for an implementation to properly instantiate a qubit ?
we give three typical examples and propose an operational characterization of qubits based on quantum observables and subsystems . .
And you have already written the first three sentences of the full article: quantum bits ( _ qubits _ ) are the elementary units of information that are used to represent quantum data @xcite .
thus , the idea of a qubit underlies all investigations in the rapidly growing science of quantum information including quantum information theory , quantum communication , quantum computation , quantum complexity , and quantum game theory @xcite .
in particular , qubits are the basic building blocks for defining the standard model of quantum computation as introduced by deutsch @xcite , which has so far provided the appropriate representation for identifying and understanding _ efficient _ ways of processing information using quantum mechanics ..
Please generate the next two sentences of the article | its investigation resulted in feasible algorithms for factoring large integers @xcite and for simulating many - particle quantum systems @xcite , two problems not known to be efficiently solvable with classical computers .
a qubit can be thought of as the extension of a classical bit obtained by applying the superposition principle . |
7,169 | Suppose that you have an abstract for a scientific paper: we investigate the evolution of spin dynamics in graphene nanoribbon superlattices ( gnsls ) with armchair and zigzag edges in the presence of a drift field .
we determine the exact evolution operator and show that it exhibits spin echo phenomena due to rapid oscillations of the quantum states along the ribbon .
the evolution of the spin polarization is accompanied by strong beating patterns .
we also provide detailed analysis of the band structure of gnsls with armchair and zigzag edges .
manipulation of electron spins using gate potentials in low dimensional semiconductor nanostructures is of interest , among other things , in that it provides a promising approach for the practical realization of robust qubit operations .
@xcite in recent years , experimental and theoretical research has sought a better understanding of the underlying physics of electrostatically defined quantum dots formed in two - dimensional electron gases for applications to solid state based quantum computing.@xcite in these devices , the spin - orbit interaction gives rise to decoherence due to the coupling of the electron spins to lattice vibrations .
hyperfine interactions between electron and nuclear spins are also a factor in some systems .
much work has focused on iii - v systems although si quantum dots @xcite are also of interest because of their relatively long decoherence times due to weak spin - orbit and hyperfine interactions .
@xcite in another promising approach , experimentalists have succeeded in fabricating and testing a low operation voltage organic field effect transistor using graphene as the gate electrode placed over a thin polymer gate dielectric layer .
@xcite graphene is promising because it exhibits extremely weak spin orbit coupling and hyperfine interactions .
@xcite in this paper , we present a theoretical investigation of the spin echo phenomena in gnsls under an externally applied drift field . we find that the spin echo is accompanied by a strong beating pattern in the....
And you have already written the first three sentences of the full article: to verify that the evolution operator ( eq . [ u ] ) is exact , we provide an example associated with the hamiltonian of spin-1/2 particle in an effective magnetic field having a known solution : @xcite @xmath98 the energy eigenvalues of ( [ ht-2 ] ) are @xmath99 where @xmath100^{1/2}$ ] .
we construct a normalized orthogonal set of eigenspinors of hamiltonian ( [ ht-2 ] ) as : @xmath101 where @xmath102 since the hamiltonian ( [ ht-2 ] ) is time dependent , the general time dependent schrdinger equations can be written as @xmath103 the exact solution of time dependent schrdinger eqs .
( [ pdt-1 ] ) and ( [ pdt-2 ] ) can be written as : @xcite ( color online ) transition probability vs time ..
Please generate the next two sentences of the article | here we chose @xmath111 and @xmath112 .
transition probabilities obtained from eqs . |
7,170 | Suppose that you have an abstract for a scientific paper: we present _ herschel _ far - infrared ( fir ) photometry of eleven quasars at redshift @xmath0 that have previously been detected at 1.2 mm .
we perform full spectral energy distribution ( sed ) fits over the wavelength range @[email protected] - 400@xmath3 m for those objects with good _ herschel _ detections .
these fits reveal the need for an additional far - infrared ( fir ) component besides the emission from a dusty agn - powered torus .
this additional fir component has temperatures of t@xmath4@xmath240 - 60k with luminosities of l@xmath5@xmath210@xmath6l@xmath7 ( accounting for 25 - 60% of the bolometric fir luminosity ) .
if the fir dust emission is due to star formation it would suggest star formation rates in excess of 1000 solar masses per year .
we show that at long wavelengths ( @xmath8 m ) the contribution of the agn - powered torus emission is negligible .
this explains how previous fir studies of high - redshift quasars that relied on single component fits to ( ground - based ) observations at @xmath9 m reached t@xmath4 and l@xmath4 values similar to our complete sed fits .
stacking the _ herschel _ data of four individually undetected sources reveals a significant average signal in the pacs bands but not in spire .
the average sed of sources with individual _ herschel _ detections shows a striking surplus in near- and mid - infrared emission when compared to common agn templates .
the comparison between two average seds ( sources with and without individual _ herschel _ detections ) matched in the uv / optical indicates that for these objects the strength of the mir emission may correlate with the strength of the fir emission . .
And you have already written the first three sentences of the full article: the presence of dust seems to be a ubiquitous property of galaxies throughout the observable universe .
even the most distant quasars at @xmath10 show evidence for copious amounts of dust ( e.g. * ? ? ?
* ; * ? ? ?.
Please generate the next two sentences of the article | * ; * ? ? ?
* ; * ? ? ? |
7,171 | Suppose that you have an abstract for a scientific paper: we study the diffraction phase of different orders via the dyson expansion series , for ultracold atomic gases scattered by a standing - wave pulse .
as these diffraction phases are not observable in a single pulse scattering process , a temporal talbot - lau interferometer consisting of two standing - wave pulses is demonstrated experimentally with a bose - einstein condensate to explore this physical effect .
the role of the diffraction phases is clearly shown by the second standing - wave pulse in the relative population of different momentum states .
our experiments demonstrate obvious effects beyond the raman - nath method , while agree well with our theory by including the diffraction phases .
in particular , the observed asymmetry in the dependence of the relative population on the interval between two standing - wave pulses reflects the diffraction phase differences .
the role of interatomic interaction in the talbot - lau interferometer is also discussed . .
And you have already written the first three sentences of the full article: the phase of a wave function plays an interesting role in quantum mechanics .
it plays a special and basic role in the quantum behaviour of a system . on the one hand , the introduction of an extra phase for a whole quantum state does not change the expectation value of an observable quantity . on the other hand
, the phase difference between two quantum states may lead to observable interference effect ..
Please generate the next two sentences of the article | atom interferometry , one of the most promising technologies suggested by modern atomic physics , is based on the phase differences between two or more states via corresponding paths @xcite . in an atom interferometer ,
the kapitza - dirac ( kd ) scattering of matter waves from a standing wave is a very powerful and versatile tool for the coherent splitting and/or mixing of momentum modes @xcite . |
7,172 | Suppose that you have an abstract for a scientific paper: motivated by recent experiments on high-@xmath0 cuprate superconductors pointing towards intra - unit - cell order in the pseudogap phase , we investigate three distinct intra - unit - cell - ordering possibilities : nematic , nematic - spin - nematic , and current - loop order .
the first two are fermi - surface instabilities involving a spontaneous charge and magnetization imbalance between the two oxygen sites in the unit cell , respectively , while the third describes circulating currents within the unit cell .
we analyze the three - band emery model of a single cuo@xmath1 layer including various on - site and nearest - neighbor interactions within a self - consistent mean - field approach .
we show how these on - site and further - neighbor repulsions suppress or enhance particular iuc orders .
in particular , we show that the attractive interactions necessary for nematic and nematic - spin - nematic orders in one - band models have their natural microscopic origin in the o - o on - site and nearest - neighbor repulsions in the three - band model .
finally , we find that while the nematic and nematic - spin - nematic orders can not coexist in this framework , the loop - current order can coexist with nematic order . .
And you have already written the first three sentences of the full article: experimental evidence for various types of symmetry breaking in the pseudogap region of the phase diagram of the high-@xmath0 cuprate superconductors has been accumulating in recent years .
neutron scattering experiments discovered a subtle staggered magnetic order in the pseudo - gap region of ybco@xcite and hg - compounds@xcite that could be accounted for by either so - called nematic - spin - nematic order@xcite or circulating current loops@xcite . on the other hand ,
neutron scattering @xcite and nernst effect @xcite measurements on ybco as well as si - stm on bscco @xcite point towards an electronic nematic state ..
Please generate the next two sentences of the article | all these states retain the translational symmetry of the underlying crystal and can thus naturally be described by breaking intra - unit - cell ( iuc ) symmetries .
hence , identifying mechanisms for these symmetry - breaking possibilities and understanding their competition is crucial for understanding the nature of the pseudogap phase . |
7,173 | Suppose that you have an abstract for a scientific paper: following the basic principles of a charge separated pulsar magnetosphere @xcite , we consider the magnetosphere be stationary in space , instead of corotating , and the electric field be uploaded from the potential distribution on the pulsar surface , set up by the unipolar induction . consequently , the plasma of the magnetosphere undergoes guiding center drifts of the gyro motion due to the transverse forces to the magnetic field .
these forces are the electric force , magnetic gradient force , and field line curvature force .
since these plasma velocities are of drift nature , there is no need to introduce an emf along the field lines , which would contradict the @xmath0 plasma condition .
furthermore , there is also no need to introduce the critical field line separating the electron and ion open field lines .
we present a self - consistent description where the magnetosphere is described in terms of electric and magnetic fields and also in terms of plasma velocities .
the fields and velocities are then connected through the space charge densities self - consistently .
we solve the pulsar equation analytically for the fields and construct the standard steady state pulsar magnetosphere . by considering the unipolar induction inside the pulsar and the magnetosphere outside the pulsar as one coupled system , and under the condition that the unipolar pumping rate exceeds the poynting flux in the open field lines , plasma pressure can build up in the magnetosphere , in particular in the closed region .
this could cause a periodic openning up of the closed region , leading to a pulsating magnetosphere , which could be an alternative for pulsar beacons .
the closed region can also be openned periodically by the build - up of toroidal magnetic field through a positive feedback cycle . .
And you have already written the first three sentences of the full article: the basic model of a pulsar had long been recognized as a perfect conductor ( neutron star ) rotating with an angular velocity @xmath1 in a hiper magnetic field @xmath2 @xcite .
considering the rotational axis and the magnetic axis both aligned in the same sense , charged particles in the neutron star are driven by the magnetic force to the surface according to their signs , with electrons towards the polar regions and ions towrds the equatorial region .
this is the faraday unipolar induction that operates homopolar generator , which extracts the energy of a conducting rigid rotator ..
Please generate the next two sentences of the article | due to its rotation in the presence of a magnetic field , the conducting pulsar surface is not an equipotential surface , contrary to the static case .
if the pulsar were surrounded by a vacuum , the separated charges would accumulate on the pulsar surface by their signs , and a counter electric field would build up inside the neutron star to counteract the magnetic force . |
7,174 | Suppose that you have an abstract for a scientific paper: thermodynamic properties of the one - dimensional ( 1d ) quantum well ( qw ) with miscellaneous permutations of the dirichlet ( d ) and neumann ( n ) boundary conditions ( bcs ) at its edges in the perpendicular to the surfaces electric field @xmath0 are calculated . for the canonical ensemble ,
analytical expressions involving theta functions are found for the mean energy and heat capacity @xmath1 for the box with no applied voltage . pronounced maximum accompanied by the adjacent minimum of the specific heat dependence on the temperature @xmath2 for the pure neumann qw and their absence for other bcs
are predicted and explained by the structure of the corresponding energy spectrum . applied field leads to the increase of the heat capacity and formation of the new or modification of the existing extrema what is qualitatively described by the influence of the associated electric potential .
a remarkable feature of the fermi grand canonical ensemble is , at any bc combination in zero fields , a salient maximum of @xmath1 observed on the @xmath2 axis for one particle and its absence for any other number @xmath3 of corpuscles .
qualitative and quantitative explanation of this phenomenon employs the analysis of the chemical potential and its temperature dependence for different @xmath3 .
it is proved that critical temperature @xmath4 of the bose - einstein ( be ) condensation increases with the applied voltage for any number of particles and for any bc permutation except the nd case at small intensities @xmath0 what is explained again by the modification by the field of the interrelated energies .
it is shown that even for the temperatures smaller than @xmath4 the total dipole moment @xmath5 may become negative for the quite moderate @xmath0 .
for either fermi or be system , the influence of the electric field on the heat capacity is shown to be suppressed with @xmath3 growing .
different asymptotic cases of , e.g. , the small and large temperatures and low and high voltages are derived....
And you have already written the first three sentences of the full article: the preceding paper @xcite discovered , among other findings , the independence of the sign of the polarization @xmath6 on the boundary conditions ( bcs ) for the one - dimensional ( 1d ) quantum well ( qw ) of the width @xmath7 placed into the uniform electric field @xmath0 that is directed perpendicular to its confining surfaces located at @xmath8 : the polarization @xmath9 of the ground state for any permutation of the dirichlet ( d ) , @xmath10 and neumann ( n ) , @xmath11 edge requirements imposed on the wavefunction @xmath12 is positive for all applied voltages while its excited - state counterparts @xmath13 , @xmath14 , for the small growing fields decrease from zero at @xmath15 to the negative values , pass through the minimum and only after this start to increase crossing zero at the @xmath16- and bc - dependent intensity @xmath17 .
immediately , one wonders : for any kind of the particles , is it possible to observe the total statistically averaged polarization that is negative at the small electric forces ?
analysis below answers this question together with the thermodynamic calculations of the corresponding energy @xmath18 and heat capacity @xmath1 ..
Please generate the next two sentences of the article | following the previous research @xcite , the qw with the particular distribution of the bcs will be denoted by the two characters , where the first ( second ) one corresponds to the edge condition at the left ( right ) interface .
similar to the discussion of the spectrum @xmath19 and polarizations @xmath13 @xcite , all energies will be measured , if not specified otherwise , in units of @xmath20 , which is a ground - state energy of the dd qw , while the unit of the electric field will be @xmath21 , and that of the polarization - @xmath22 , with @xmath23 being the particle mass and @xmath24 denoting the absolute value of the electronic charge . |
7,175 | Suppose that you have an abstract for a scientific paper: from a simple path integral involving a variable volatility in the velocity differences , we obtain velocity probability density functions with exponential tails , resembling those observed in fully developed turbulence .
the model yields realistic scaling exponents and structure functions satisfying extended self - similarity .
but there is an additional small scale dependence for quantities in the inertial range , which is linked to a slow approach to kolmogorov ( 1941 ) scaling occurring in the large distance limit .
.25in.25 in 8.5 in the universal features displayed by fully developed hydrodynamic turbulence are still not fully understood .
kolmogorov ( 1941 ) @xcite showed how a set of statistical quantities known as structure functions are expected depend on the length scale @xmath0 as power laws with predicted exponents .
experimental measurements have indicated that while these predictions are close to the truth , the predicted exponents are not exactly realized . in the face of this experimental input , much effort has been devoted towards understanding the origin of these anomalies in the scaling exponents , while retaining the notion that current experiments are observing an `` inertial range '' where strict power law scaling holds .
in this paper we will investigate what appears to be a loop - hole in this reasoning . in spite of impressive advances made in the experimental studies
, the fact remains that the scaling exponents have been deduced by looking at scaling regions extending over little more than one decade in @xmath0 @xcite .
this leaves open the possibility that a small but significant departure from strict power law scaling is still consistent with the data .
we will argue that this possible departure is sufficient to allow the observed anomalies in the exponents to be nothing more than a transient effect related to intermittency , and that the true power law scaling only occurs on larger scales .
this very large distance scaling could take the form....
And you have already written the first three sentences of the full article: i thank brian smith for discussions .
this research was supported in part by the natural sciences and engineering research council of canada .
99 a. n. kolmogorov , dokl ..
Please generate the next two sentences of the article | nauk sssr 30 , 9 ( 1941 ) .
u. frisch , `` turbulence : the legacy of a.n . |
7,176 | Suppose that you have an abstract for a scientific paper: the main goal of the rem project is the observation of prompt afterglow of gamma ray burst ( grb ) events .
such observations at near infrared ( nir ) wavelengths are even very promising , since they allow to monitor high z ly-@xmath0 absorbed bursts as well as events occurring in dusty star forming regions .
in addition to grb science , a large amount of time ( @xmath1 ) will be available for different scientific targets : among these the study of variability of stellar objects open exciting new perspectives . .
And you have already written the first three sentences of the full article: in the last decade , mainly due to the observations by _ beppo_sax and related optical earth based follow up ,
the physics of grbs and their afterglow started to be understood .
however , the intrinsic duration of the observational process , mainly due to the use of device non.
Please generate the next two sentences of the article | optimized for fast response , did not allow up to now to monitor the prompt afterglow , i.e. the emission in the few seconds after the burst ( except in one case , grb990123 ) .
in the next few years , dedicated missions such as heteii or swift and of other space borne high |
7,177 | Suppose that you have an abstract for a scientific paper: the paper presents a software tool for analysis and interactive engagement in various logical reasoning tasks . a first feature of the program consists in providing an interface for working with logic - specific repositories of formal knowledge .
a second feature provides the means to intuitively visualize and interactively generate the underlying logical structure that propels customary logical reasoning tasks .
starting from this we argue that both aspects have didactic potential and can be integrated in teaching activities to provide an engaging learning experience . .
And you have already written the first three sentences of the full article: the tradition of using diagrammatic representations of formal structure in logical reasoning stretches back to times when sand or papyrus were the media for visualizations .
the tradition of using interactive software tools in logical reasoning is a recent refinement of an ancient interest .
this stretches back to the age of compact disk distributed software alongside paper printed books , with @xcite as a paradigmatic example , and plenty others , many of which have been presented at this venue @xcite . using didactic software online for logic education and e - learning is an equally respectable tradition going back to the age when java applets roamed on the web , with @xcite as a representative example , and plenty others , many of which have been also presented at this venue @xcite ..
Please generate the next two sentences of the article | latest trends in this evolution are dissemination of logic courseware freely available online , with @xcite as a pertinent example , alongside didactic software tools built on a technology stack up to date with current web standards , with @xcite as a relevant illustration .
this is the general trend for many other fields across the curriculum @xcite . |
7,178 | Suppose that you have an abstract for a scientific paper: we investigate the 3.45-ev luminescence band of spontaneously formed gan nanowires on si(111 ) by photoluminescence and cathodoluminescence spectroscopy .
this band is found to be particularly prominent for samples synthesized at comparatively low temperatures . at the same time , these samples exhibit a peculiar morphology , namely , isolated long nanowires intersecting a dense matrix of short ones .
cathodoluminescence intensity maps reveal the 3.45-ev band to originate primarily from the long nanowires .
transmission electron microscopy shows that these long nanowires are either ga polar and are joined by an inversion domain boundary with their short n - polar neighbors , or exhibit a ga - polar core surrounded by a n - polar shell with a tubular inversion domain boundary at the core / shell interface . for samples grown at high temperatures , which exhibit a uniform nanowire morphology ,
the 3.45-ev band is also found to originate from particular nanowires in the ensemble and thus presumably from inversion domain boundaries stemming from the coexistence of n- and ga - polar nanowires . for several of the investigated samples , the 3.45-ev band splits into a doublet .
we demonstrate that the higher - energy component of this doublet arises from the recombination of two - dimensional excitons free to move in the plane of the inversion domain boundary .
in contrast , the lower - energy component of the doublet originates from excitons localized in the plane of the inversion domain boundary . we propose that this in - plane localization is due to shallow donors in the vicinity of the inversion domain boundaries . .
And you have already written the first three sentences of the full article: the promising optoelectronic properties of spontaneously formed gan nanowires ( nws ) reported in the pioneering works of @xcite and @xcite have triggered world - wide research activities that have led to the demonstration of light - emitting @xcite and light - harvesting devices @xcite based on group - iii - nitride nws . despite this progress ,
several open questions still exist regarding the spontaneous formation of gan nws and their structural and optical properties .
in particular , a prominent band at 3.45 ev has been widely reported in the low - temperature photoluminescence ( pl ) spectra of gan nws grown by plasma - assisted molecular beam epitaxy ( pambe ) on si(111 ) @xcite ..
Please generate the next two sentences of the article | the origin of this band in gan nws has been a subject of a lively debate for almost two decades . in bulk
gan , two different recombination mechanisms are known to manifest themselves by luminescence lines at about 3.45 ev : first , the two - electron satellite ( tes ) of the donor - bound exciton transition [ @xmath0 @xcite and , second , excitons bound to inversion domain boundaries @xcite . the intensity of the tes transitions in bulk gan is about two orders of magnitude lower than that of the related @xmath1line @xcite . |
7,179 | Suppose that you have an abstract for a scientific paper: the dynamics of grb jets during the afterglow phase have an important effect on the interpretation of their observations and for inferring key physical parameters such as their true energy and event rate .
semi - analytic models generally predict a fast lateral expansion , where the jet opening angle asymptotically grows exponentially with its radius . numerical simulations , however , show a much more modest lateral expansion , where the jet retains memory of its initial opening angle for a very long time , and the flow remains non - spherical until it becomes sub - relativistic , and only then gradually approaches spherical symmetry . here
we suggest a new analytic model based on a new physically derived recipe for the lateral expansion .
we also generalize the model by relaxing the common approximations of ultra - relativistic motion and a narrow jet opening angle .
we find that the new analytic model fits much better the results of numerical simulations , mainly because it remains valid also in the mildly relativistic , quasi spherical regime .
this model shows that for modest initial jet half - opening angles , @xmath0 , the outflow is not _
sufficiently _ ultra - relativistic when its lorentz factor reaches @xmath1 and therefore the sideways expansion is rather slow , showing no rapid , exponential phase . on the other hand , we find that jets with an extremely narrow initial half - opening angle , of about @xmath2 or so , which are still sufficiently ultra - relativistic at @xmath1 , do show a phase of rapid , exponential lateral expansion .
however , even such jets that expand sideways exponentially are still not spherical when they become sub - relativistic . .
And you have already written the first three sentences of the full article: the ultra - relativistic outflows that power gamma - ray bursts ( grbs ) are thought to be collimated into narrow jets ( for reviews see * ? ? ?
* ; * ? ? ?
* ; * ? ? ?.
Please generate the next two sentences of the article | the evidence for this is rather indirect , however , since their images are usually unresolved , and in the best case ( grb 030329 ) the late time radio afterglow image was only marginally resolved @xcite .
the different lines of evidence for jets in grbs include analogy to other astrophysical relativistic outflow sources such as active galactic nuclei or micro - quasars ( e.g. * ? ? ? |
7,180 | Suppose that you have an abstract for a scientific paper: we introduce a self - consistent stochastic coarse - graining method , which includes both metric and scalar field fluctuations , to investigate the back reaction of long wavelength perturbations in single - scalar driven inflation , up to the second ( one loop ) order .
we demonstrate that , although back reaction can not be significant during the last 70 e - foldings of inflation with a smooth potential , there exist non - smooth inflaton potentials which allow significant back reaction , and are also consistent with cosmological observations .
such non - smooth potentials may lead to the generation of massive primordial black holes , which could be further used to constrain / verify these models . .
And you have already written the first three sentences of the full article: in the context of inflationary cosmology , initial seeds of today s structures are generated in the de - sitter phase of an inflationary universe , as a consequence of quantum vacuum fluctuations ( see e.g. @xcite for a comprehensive overview of the theory of cosmological fluctuations and @xcite for a recent introductory overview ) . the standard way of analyzing these fluctuations is through linear perturbation theory .
however , the linear analyses is limited by the non - linear nature of the einstein equations , and in particular , the presence of perturbations is likely to affect the evolution of the background cosmology at the non - linear level .
the back reaction of short wavelength gravity waves on an expanding friedmann - robertson - walker ( frw ) cosmology is a well - understood problem @xcite ..
Please generate the next two sentences of the article | however , in the context of inflationary and post - inflationary cosmology , the scalar metric fluctuations ( fluctuations coupled to energy density and pressure perturbations ) are believed to dominate over the effects of gravity waves , and thus , it is of great interest to understand the possible back reaction of these scalar perturbations on the cosmological background .
furthermore , during inflation , the phase space of infrared modes ( defined as modes with wavelength greater than the hubble radius ) grows exponentially , whereas the phase space of the ultraviolet modes does not grow and since the amplitude of the associated metric fluctuations of these infrared modes does _ not _ decrease in time , the back reaction of these infrared modes may grow to be significant . |
7,181 | Suppose that you have an abstract for a scientific paper: we use a standard bead - spring model and molecular dynamics simulations to study the static properties of symmetric linear multiblock copolymer chains and their blocks under poor solvent conditions in a dilute solution from the regime close to theta conditions , where the chains adopt a coil - like formation , to the poorer solvent regime where the chains collapse obtaining a globular formation and phase separation between the blocks occurs .
we choose interaction parameters as is done for a standard model , i.e. , the lennard - jones fluid and we consider symmetric chains , i.e. , the multiblock copolymer consists of an even number @xmath0 of alternating chemically different a and b blocks of the same length @xmath1 . we show how usual static properties of the individual blocks and the whole multiblock chain can reflect the phase behavior of such macromolecules .
also , how parameters , such as the number of blocks @xmath0 can affect properties of the individual blocks , when chains are in a poor solvent for a certain range of @xmath0 .
a detailed discussion of the static properties of these symmetric multiblock copolymers is also given .
our results in combination with recent simulation results on the behavior of multiblock copolymer chains provide a complete picture for the behavior of these macromolecules under poor solvent conditions , at least for this most symmetrical case .
due to the standard choice of our parameters , our system can be used as a benchmark for related models , which aim at capturing the basic aspects of the behavior of various biological systems . .
And you have already written the first three sentences of the full article: polymers combining chemically different monomeric units on their structure found very much theoretical and experimental interest , as , for instance , diblock copolymers , where in the case of a linear chain one block of the chain consists of one type of monomers , while the other part of another type of monomers .
these macromolecules have already found particular interest as they form different structures depending on their structural parameters , thermodynamics conditions , etc . for
a standard theoretical review one could see ref ..
Please generate the next two sentences of the article | @xcite and references therein .
we underline that the motivation for studying such systems stems from the fact that these materials are used in industrial scale @xcite and also in very advanced technological applications ( as an example one may look a very recent review ref . |
7,182 | Suppose that you have an abstract for a scientific paper: in this contribution i show that by combining imaging and integral - field spectroscopy it is possible to unravel the internal structure of galaxies .
in particular , i will present the photometric and kinematic evidence for discs linking them with stellar angular momentum content of early - type galaxies .
furthermore , i show that the existence of both fast rotators with core and slow rotators with core - less nuclear light profiles challenges the standard formation scenarios for fast and slow rotators and suggests new pathways of mass assembly . .
And you have already written the first three sentences of the full article: in the seminal paper @xcite , roger davies and collaborators showed that early - type galaxies ( etgs ) have divers kinematics , ranging from fainter and rotational supported to brighter and dispersion dominated systems .
this picture is effectively still with us ( e.g. * ? ? ?
* ; * ? ? ?.
Please generate the next two sentences of the article | * ) , although the focus has somewhat changed . in particular , the usage of integral field spectrographs and the analysis of kinematic maps enable a more detailed analysis of the internal structure of galaxies.=-2 the atlas@xmath0 project @xcite is a survey of morphologically selected etgs observable with the sauron integral - field spectrograph @xcite mounted on the william herschel telescope . the galaxies selected were brighter than -21.5 magnitude in the 2mass k@xmath1 band and within 42 mpc in order to properly exploit sauron s short wavelength range . out of about 900 such galaxies ,
260 etgs were selected , based purely on their morphology . |
7,183 | Suppose that you have an abstract for a scientific paper: we present iram plateau de bure interferometer 3 mm observations of co _
j_(1@xmath00 ) emission in two 24@xmath1m - selected starburst galaxies in the outskirts ( @xmath223@xmath3 ) of the rich cluster cl0024 + 16 ( @xmath4 ) .
the galaxies inferred far - infrared luminosities place them in the luminous infrared galaxy class ( lirgs , @xmath5 ) , with star formation rates of @xmath260@xmath6yr@xmath7 .
strong co _ j_(1@xmath00 ) emission is detected in both galaxies , and we use the co line luminosity to estimate the mass of cold molecular gas , @xmath8 . assuming @xmath9 , we estimate @xmath10@xmath11 for the two galaxies .
we estimate the galaxies dynamical masses from their co line - widths , @xmath12@xmath13 , implying large cold gas fractions in the galaxies central regions . at their current rates
they will complete the assembly of @xmath14 and double their stellar mass within as little as @xmath2150myr . if these galaxies are destined to evolve into s0s , then the short time - scale for stellar mass assembly implies that their major episode of bulge growth occurs while they are still in the cluster outskirts , long before they reach the core regions .
subsequent fading of the disc component relative to the stellar bulge after the gas reservoirs have been exhausted could complete the transformation of spiral - to - s0 .
[ firstpage ] clusters : galaxies , clusters : individual : cl0024 + 16 , galaxies : starburst , evolution @lcccccccccc target & @xmath15 & @xmath16 & @xmath17 & @xmath18 & sfr & @xmath19 & @xmath20 & @xmath21 & @xmath22 & ( h m s ) & ( @xmath23 @xmath24 @xmath25 ) & & ( @xmath26 ) & ( @xmath6yr@xmath7 ) & ( kms@xmath7 ) & ( kms@xmath7 ) & ( 10@xmath27 k km s@xmath7
pc@xmath28 ) & ( @xmath29 ) mipsj002621.7 & 00 26 21.7 & + 17 19 26.4 & 0.3803 & @xmath30 & @xmath31 & 144@xmath3213 & @xmath33 & @xmath34 & @xmath35 mipsj002721.0 & 00 27 21.1 & + 16 59 49.9 & 0.3964 & @xmath36 & @xmath37 & 158@xmath3234 & @xmath38 , @xmath39 & @xmath40 & @xmath41 .
And you have already written the first three sentences of the full article: one key requirement for a starburst is the presence of a reservoir of dense , cold gas that can be efficiently converted to stars . for galaxies entering rich clusters
this is especially important , because they are expected to be affected by mechanisms that can remove cold gas from the haloes and discs of infalling galaxies ( e.g.ram-pressure stripping , gunn & gott 1972 ) or prevent further cooling of gas within galaxies dark matter halos ( starvation or strangulation , e.g. larson , tinsley & caldwell 1980 ; bekki , couch & shioya 2002 ) .
this environmental dependence has a profound influence on cluster galaxies evolutionary histories , the net effect of which is the eventual termination of star formation ( there is virtually no residual star formation in the cores of local clusters ) . the observational evidence for the gradual truncation of star formation in clusters is the conspicuous disappearance of star - forming disc galaxies in the cores of rich clusters since @xmath42 . it has been proposed that the spiral galaxies in distant clusters must be transforming into passive lenticular ( s0 ) galaxies , since the fraction of s0s in rich clusters is believed to increase at the same time that the spirals begin to vanish ( dressler et al.1997 ) ..
Please generate the next two sentences of the article | however , the detailed nature of the physics controlling this evolution is still poorly understood .
for example , what process is responsible for the transformation of the bulge - to - disc ratio of the spiral population ? ( kodama & smail 2001 ) . |
7,184 | Suppose that you have an abstract for a scientific paper: we study orbital and physical properties of trojan asteroids of jupiter .
we try to discern all families previously discussed in literature , but we conclude there is only one significant family among trojans , namely the cluster around asteroid ( 3548 ) eurybates .
it is the only cluster , which has all of the following characteristics : ( i ) it is clearly concentrated in the proper - element space ; ( ii ) size - frequency distribution is different from background asteroids ; ( iii ) we have a reasonable collisional / dynamical model of the family .
henceforth , we can consider it as a real collisional family .
we also report a discovery of a possible family around the asteroid ( 4709 ) ennomos , composed mostly of small asteroids .
the asteroid ( 4709 ) ennomos is known to have a very high albedo @xmath0 , which may be related to a hypothetical cratering event which exposed ice ( fernndez et al .
2003 ) .
the relation between the collisional family and the exposed surface of the parent body is a unique opportunity to study the physics of cratering events . however , more data are needed to confirm the existence of this family and its relationship with ennomos .
[ firstpage ] celestial mechanics minor planets , asteroids methods : @xmath1-body simulations . .
And you have already written the first three sentences of the full article: trojans of jupiter , which reside in the neighbourhood of @xmath2 and @xmath3 lagrangian points , serve as an important test of the planetary migration theory ( morbidelli et al .
their inclination distribution , namely the large spread of @xmath4 , can be explained as a result of chaotic capture during a brief period when jupiter and saturn encountered a 1:2 mean - motion resonance .
moreover , the late heavy bombardment provides the timing of this resonant encounter @xmath5gyr ago ( gomes et al ..
Please generate the next two sentences of the article | it is thus important to understand the population of trojans accurately .
there are several unresolved problems regarding trojans , however , for example the number of families , which is a stringent constraint for collisional models . |
7,185 | Suppose that you have an abstract for a scientific paper: we experimentally study the violation of the cglmp inequality for entangled 2-qubit and 2-qutrit states with different degrees of entanglement using numerically optimized measurement settings . the qudits are encoded and manipulated in the frequency spectrum of broadband energy - time entangled photons by taking into account a spatial light modulator .
the latter allows to discretize the spectrum into bins . by controlling each frequency bin individually ,
the generation of maximally and non - maximally entangled qutrits is verified through quantum state tomography . .
And you have already written the first three sentences of the full article: for many years people were puzzling over the question if quantum mechanics as the underlying theory to describe non - classical phenomena is complete .
after the einstein , podolsky , and rosen ( epr ) paradox@xcite , published in 1935 , it was john steward bell who presented in 1964 a seminal theorem to tackle this question.@xcite he accepted the epr conclusion as a working principle and developed what is called a local hidden variable model ( lhvm ) in which measurement outcomes are completely predetermined and only affected locally .
the assumptions of this model impose linear constraints on experimental input - output correlations in a bipartite system which have become known as bell inequalities ..
Please generate the next two sentences of the article | an important feature in the context of an experimental test of bell s inequality is entanglement@xcite , a quantum mechanical phenomenon which occurs if the state of a particle pair can not be written as independent single particle states .
furthermore , due to entanglement , bell showed that it is impossible to reproduce quantum correlations in the framework of a lhvm which implies a non - local behavior of nature . |
7,186 | Suppose that you have an abstract for a scientific paper: we investigate density perturbations in the chain inflation scenario , where the inflaton undergoes successive tunneling transitions along one field direction .
first we show that when the bubble walls associated with such a phase transition meet , they induce the next phase transition and continue to propagate as phase interfaces
. then we present an analytical calculation of the density fluctuations and an estimate of non - gaussianities such as @xmath0 , which we find to be small ( of order 1 ) . to get the right amplitude for the power spectrum
, there have to be @xmath1 phase transitions per hubble time , a significant model building challenge .
we find that working models of chain inflation must be rather strongly coupled , and thus have a very limited range of validity as effective field theories .
we discuss generalizations to the multiple field case , the curvaton scenario , and noncanonical kinetic terms . .
And you have already written the first three sentences of the full article: in a scenario dubbed `` chain inflation '' @xcite it was suggested that the dynamics of inflation may be dominated by a series ( chain ) of phase transitions , each induced by the quantum nucleation of bubbles ( tunneling events ) .
provided that each phase transition occurs much less than one hubble time after the previous one , this scenario is free from the problem of `` old inflation '' @xcite that the space still in the previous phase continues to inflate and prevents the completion of a phase transition .
the need for several phase transitions per hubble time , and the requirement that inflation persist for at least @xmath2 hubble times to solve the flatness and horizon problems , means that the scenario requires a potential with a large number of minima , tunneled through in sequence ..
Please generate the next two sentences of the article | this is a challenge for model building but not an insurmountable one .
the density perturbations arising from chain inflation have been investigated in @xcite . a simplified model of chain inflation |
7,187 | Suppose that you have an abstract for a scientific paper: we consider a region @xmath0 in @xmath1 with boundary @xmath2 and a metric @xmath3 on @xmath0 conformal to the euclidean metric .
we analyze the inverse problem , originally formulated by dix @xcite , of reconstructing @xmath3 from boundary measurements associated with the single scattering of seismic waves in this region . in our formulation the measurements
determine the shape operator of wavefronts outside of @xmath0 originating at diffraction points within @xmath0 .
we develop an explicit reconstruction procedure which consists of two steps . in the first step
we reconstruct the directional curvatures and the metric in what are essentially riemmanian normal coordinates ; in the second step we develop a conversion to cartesian coordinates .
we admit the presence of conjugate points . in dimension @xmath4
both steps involve the solution of a system of ordinary differential equations . in dimension @xmath5 the same is true for the first step , but the second step requires the solution of a cauchy problem for an elliptic operator which is unstable in general .
the first step of the procedure applies for general metrics . .
And you have already written the first three sentences of the full article: we consider a region , @xmath0 , in @xmath1 with a smooth boundary @xmath2 .
we assume that there is a riemannian metric , @xmath3 , on @xmath0 that is conformal to the euclidean metric with conformal factor @xmath6 where @xmath7 is strictly positive .
this means that @xmath8 , where @xmath9 is the euclidean metric , or , in cartesian coordinates @xmath10 , @xmath11 ..
Please generate the next two sentences of the article | we analyze the inverse problem of reconstructing @xmath3 based on measurements of the curvature of wavefronts produced by point diffractors located inside @xmath0 and propagated according to the wave operator on @xmath12 .
indeed , geodesics for the metric @xmath3 are rays following the propagation of singularities by a parametrix corresponding to this wave operator . in the seismic context |
7,188 | Suppose that you have an abstract for a scientific paper: it is desirable to implement an efficient quantum information process demanding fewer quantum resources .
we designed two compact quantum circuits for determinately implementing four - qubit toffoli and fredkin gates on single - photon systems in both the polarization and spatial degrees of freedom ( dofs ) via diamond nitrogen - vacancy ( nv ) centers in resonators .
the gates are heralded by the electron spins associated with the diamond nv centers .
in contrast to the ones with one dof , our implementations reduce the quantum resource and are robust against the decoherence .
evaluations of fidelities and efficiencies of our gates show that our schemes may be implemented with current technology . .
And you have already written the first three sentences of the full article: quantum computer offers great advantages over the classical computer@xcite , such as tremendous speedup , efficiently searching for unordered database , and factorizing large numbers .
quantum gates are the fundamental elements for the quantum computer .
quantum computation , quantum networks , and quantum algorithms can be decomposed into a set of universal gates and single - qubit gates@xcite ..
Please generate the next two sentences of the article | controlled - not ( cnot ) gate or controlled - phase gate is the most popular nontrivial universal gate@xcite , and considerable progresses have been made on them@xcite . in recent years , constructions of the toffoli gate@xcite or
fredkin gate@xcite has been addressed from various perspectives , and these two universal multiqubit - control gates are the key operations in quantum networks , quantum phase estimate , fault - error quantum computing , quantum - error correction , quantum shor s algorithm@xcite , quantum grover s algorithm@xcite , and optimal long s algorithm@xcite |
7,189 | Suppose that you have an abstract for a scientific paper: we report a first - principles projector augmented wave ( paw ) study on na@xmath0coo@xmath1 . with the sodium ion ordered insulating phase being identified in experiments ,
pure density functional calculations fail to predict an insulating ground state , which indicates that na ordering alone can not produce accompanying co charge ordering , if additional correlation is not properly considered . at this level of theory ,
the most stable phase presents ferromagnetic ordering within the coo@xmath1 layer and antiferromagnetic coupling between these layers .
when the on - site coulomb interaction for co @xmath2 orbitals is included by an additional hubbard parameter @xmath3 , charge ordered insulating ground state can be obtained .
the effect of on - site interaction magnitude on electronic structure is studied . at a moderate value of @xmath3 ( 4.0 ev for example ) ,
the ground state is antiferromagnetic , with a co@xmath4 magnetic moment about 1.0 @xmath5 and a magnetic energy of 0.12 ev / co .
the rehybridization process is also studied in the dft+u point of view . .
And you have already written the first three sentences of the full article: na@xmath6coo@xmath1 was originally studied as a kind of rechargeable battery material@xcite and thermoelectric material@xcite .
more recently , the discovery of the superconductivity in its hydrated x=0.35 compound@xcite , where the effect of hydration is found to be limited to lattice expansion@xcite , makes it receive a renewed interest .
na@xmath6coo@xmath1 has a crystal structure consisting of 2d triangular lattice co sheets , octahedrally coordinated with o above and below the co planes , and layers of na ions sandwiched between the coo@xmath1 sheets ..
Please generate the next two sentences of the article | the phase diagram of na@xmath6coo@xmath1 has been determined by changing the na content @xmath7 using a series of chemical reactions@xcite .
their electronic and magnetic properties are found to be strongly dependent on the number of charge carriers introduced by deviations from stoichiometry in the na sublattice . |
7,190 | Suppose that you have an abstract for a scientific paper: we use cosmological simulations to study the origin of primordial star - forming clouds in a @xmath0cdm universe , by following the formation of dark matter halos and the cooling of gas within them . to model the physics of chemically pristine gas
, we employ a non - equilibrium treatment of the chemistry of 9 species ( e@xmath1 , h , h@xmath2 , he , he@xmath3 , he@xmath4 , h@xmath5 , h@xmath6 , h@xmath1 ) and include cooling by molecular hydrogen . by considering cosmological volumes , we are able to study the statistical properties of primordial halos and the high resolution of our simulations enables us to examine these objects in detail .
in particular , we explore the hierarchical growth of bound structures forming at redshifts @xmath7 with total masses in the range @xmath8 .
we find that when the amount of molecular hydrogen in these objects reaches a critical level , cooling by rotational line emission is efficient , and dense clumps of cold gas form .
we identify these `` gas clouds '' as sites for primordial star formation . in our simulations
, the threshold for gas cloud formation by molecular cooling corresponds to a critical halo mass of @xmath9 , in agreement with earlier estimates , but with a weak dependence on redshift in the range @xmath10 .
the complex interplay between the gravitational formation of dark halos and the thermodynamic and chemical evolution of the gas clouds compromises analytic estimates of the critical h@xmath5 fraction .
dynamical heating from mass accretion and mergers opposes relatively inefficient cooling by molecular hydrogen , delaying the production of star - forming clouds in rapidly growing halos .
we also investigate the impact of photo - dissociating ultra - violet ( uv ) radiation on the formation of primordial gas clouds .
we consider two extreme cases by first including a uniform radiation field in the optically thin limit and secondly by accounting for the maximum effect of gas self - shielding in virialized regions . for radiation....
And you have already written the first three sentences of the full article: the first stars in the universe almost certainly originated under conditions rather different from those characterizing present - day star formation . because elements heavier than lithium are thought to be produced exclusively through stellar nucleosynthesis , the primordial gas must have been chemically pristine , presumably resulting in stars of unusually low metallicity .
the recent discovery of an ultra metal - poor star by christlieb et al .
( 2002 ) suggests that stellar relics from this era exist even today in our own galaxy ..
Please generate the next two sentences of the article | such old stars offer invaluable information about the history of structure formation and the chemical composition of the gas in the very early universe .
the study of the cooling of primordial gas and the origin of the first baryonic objects has a long history ( e.g. , matsuda , sato & takeda 1969 ; kashlinsky & rees 1983 ; couchman & rees 1986 ; fukugita & kawasaki 1991 ; tegmark et al . |
7,191 | Suppose that you have an abstract for a scientific paper: observations indicate that the universe is effectively flat , but they do not rule out a closed universe .
the role of positive curvature is negligible at late times , but can be crucial in the early universe . in particular
, positive curvature allows for cosmologies that originate as einstein static universes , and then inflate and later reheat to a hot big bang era .
these cosmologies have no singularity , no beginning of time " , and no horizon problem .
if the initial radius is chosen to be above the planck scale , then they also have no quantum gravity era , and are described by classical general relativity throughout their history . .
And you have already written the first three sentences of the full article: the standard " inflationary model is based on a flat ( @xmath0 ) friedmann - robertson - walker ( frw ) geometry , motivated by the fact that inflationary expansion rapidly wipes out any original spatial curvature .
however , even though inflation drives the curvature term , @xmath1 towards zero , or equivalently , drives the total density parameter @xmath2 towards 1 , this does _ not _ imply that @xmath3 .
conditions leading to the open set of values @xmath4 are far less fine - tuned than those corresponding precisely to @xmath3 ( although closed models have other fine - tuning aspects ) . but irrespective of any arguments about fine - tuning , the spatial curvature of the real universe is in principle determined by observations ; theory will have to give way to data if the data clearly tell us that @xmath5 ..
Please generate the next two sentences of the article | recent cosmic microwave background ( cmb ) and other data @xcite are not conclusive , but include the possibility that @xmath6 , with @xmath7 future experiments such as planck will reduce these error bars and give more accurate information about the curvature of the universe .
( note that the true global value of @xmath8 and its observed value in the local hubble volume may differ due to cosmological perturbations seeded by inflation . ) |
7,192 | Suppose that you have an abstract for a scientific paper: we consider the wiretap channel model under the presence of a hybrid , half duplex adversary that is capable of either jamming or eavesdropping at a given time .
we analyzed the achievable rates under a variety of scenarios involving different methods for obtaining transmitter csi .
each method provides a different grade of information , not only to the transmitter on the main channel , but also to the adversary on all channels .
our analysis shows that main csi is more valuable for the adversary than the jamming csi in both delay - limited and ergodic scenarios .
similarly , in certain cases under the ergodic scenario , interestingly , no csi may lead to higher achievable secrecy rates than with csi . .
And you have already written the first three sentences of the full article: information theoretic security has received a significant attention recently .
one mainstream direction has been on the wireless transmission of confidential messages from a source to a destination , in the presence of internal and/or external eavesdroppers . toward achieving that goal
, the communicating pair exploits the stochasticity and the asymmetry of wireless channels between the communicating pair and the eavesdroppers ..
Please generate the next two sentences of the article | a stochastic encoder at the transmitter makes use of the available channel state information ( csi ) in a way for the mutual information leaked to the adversaries remain arbitrarily small .
it is designed in a way that , even when the adversaries have access to the full csi of the main channel , i.e. , between the transmitter and the receiver as well as the eavesdropper channel , i.e. , between the transmitter and itself , it still will obtain an arbitrarily low rate of information on the message . |
7,193 | Suppose that you have an abstract for a scientific paper: a master equation approach is applied to a reversible and conservative cellular automata model ( q2r ) .
the q2r model is a dynamical variation of the ising model for ferromagnetism that possesses quite a rich and complex dynamics . the configurational space is composed by a huge number of cycles with exponentially long periods .
following nicolis and nicolis [ _ phys .
rev . _ * a 38 * , 427 - 433 ( 1988 ) ] , a coarse - graining approach is applied to the time series of the total magnetization leading to a master equation that governs the macroscopic irreversible dynamics of the q2r automata .
the methodology is replicated for various lattice sizes . in the case of small systems
, it is shown that the master equation leads to a tractable probability transfer matrix of moderate size which provides a master equation for a coarse - grained probability distribution .
the method is validated and some explicit examples are discussed . .
And you have already written the first three sentences of the full article: in statistical physics one basically considers a large set of reversible and conservative ordinary differential equations for the description of particle dynamics .
the temporal evolution for this cumbersome problem , even for a modest number of particles , requires a statistical description which introduces the concept of probability distribution function ( pdf ) for the phase space of the system .
irreversibility , equilibrium , and more important non - equilibrium properties , surge from this probability conception of systems ( with a large number of degrees of freedom ) and its deterministic evolution ..
Please generate the next two sentences of the article | briefly , the methodology reduces ( under some assumptions ) to a kinetic description which displays an irreversible behavior to equilibrium observed in macroscopic systems .
the assumptions for this approach are : i ) macroscopically , a system is described by a finite set of observables ; ii ) the robust instability of the microscopic motions which is at the basis of the sensibility to initial conditions and the ergodic assumption . |
7,194 | Suppose that you have an abstract for a scientific paper: holographic models of superconductors successfully reproduce certain experimental features of high - temperature superconductors , such as a large gap - to-@xmath0 ratio compared to that of conventional superconductors . by deconstructing the extra dimension of these holographic models ,
similar phenomenology is described by a class of models defined in the natural dimension of the superconducting system .
we analyze the sensitivity of certain observables in holographic and deconstructed holographic superconductors to details of the extra - dimensional spacetime .
our results support the notion that certain quantitative successes of simple models of this type are accidental .
however , we also find a certain universal relationship between superconducting observables . .
And you have already written the first three sentences of the full article: holographic models of nonperturbative physical systems have been more successful quantitatively than should have been expected .
the most developed applications of holographic model building are to quantum chromodynamics ( qcd ) @xcite , electroweak symmetry breaking @xcite and condensed matter systems , especially superconductors @xcite .
arguments based on insensitivity to model details @xcite , approximate conformal invariance @xcite and decoupling of high - dimension states and operators @xcite have been put forward in an attempt to understand the unreasonable effectiveness of some of these models ..
Please generate the next two sentences of the article | holographic models of 3 + 1 dimensional systems are 4 + 1 dimensional theories in which the behavior of fields near the boundary of the spacetime , typically anti - de sitter ( ads ) space , determines the properties of the corresponding lower - dimensional system .
however , gauge theories in more than 3 + 1 dimensions are generally nonrenormalizable . |
7,195 | Suppose that you have an abstract for a scientific paper: the dynamics of a test particle interacting with diffusing impurities in one dimension is investigated analytically and numerically . in the absence of an applied external force
, the dynamics of the particle can be characterized by a distribution of monotonic excursions @xmath0 , which scales as a power law with an exponent @xmath1 . when the particle is driven at a slow constant velocity
, there is again a power law distribution for the monotonic changes of the force @xmath2 , which is characterized by a similar exponent @xmath3 .
these results can be understood from the theory of random walks . .
And you have already written the first three sentences of the full article: the interaction of driven particles , flexible lines and membranes etc . with disorder is an important topic in condensed matter physics @xcite .
usually , this disorder is taken to be _ quenched _ , or frozen , such that its properties do not change within the relevant time scales . however , under certain conditions , this changes as in the case of the diffusion of solute atoms in metallic alloys @xcite or oxygen vacancies in superconductors @xcite .
the mobile impurities play an important role in the dynamics of such systems , as evidenced for example by the portevin - le chatelier ( plc ) effect in solid solutions @xcite ..
Please generate the next two sentences of the article | there , within a certain range of temperatures and applied strain rates , the dynamic interaction of lattice dislocations and diffusing solute atoms result in phenomena such as negative strain rate sensitivity of the flow stress , giving rise to macroscopic serrations in the stress strain curve and strain localization in the form of bands of activity of various types @xcite . here , we consider the simple test problem of a single particle interacting with a cloud of diffusing impurities , with the dynamics constrained in one dimension ( a line ) . we restrict ourselves to the region of the parameter space
in which the impurities have a vanishingly small probability to escape from the vicinity of the particle . despite its apparent simplicity , |
7,196 | Suppose that you have an abstract for a scientific paper: we analyze inexact fixed point iterations where the generating function contains an inexact solve of an equation system to answer the question of how tolerances for the inner solves influence the iteration error of the outer fixed point iteration .
important applications are the picard iteration and partitioned fluid structure interaction .
we prove that the iteration converges irrespective of how accurate the inner systems are solved , provided that a specific relative termination criterion is employed , whereas standard relative and absolute criteria do not have this property . for the analysis ,
the iteration is modelled as a perturbed fixed point iteration and existing analysis is extended to the nested case @xmath0 .
= 0.9 _ @xmath1 numerical analysis , centre for the mathematical sciences , lund university , box 118 , 22100 lund , sweden + institute of mathematics , university of kassel , heinrich - plett - str .
40 , 34132 kassel , germany + department of mathematics / computer science , university of osnabrck , albrechtstr .
28a , 49076 osnabrck , germany + email : philipp.birkenna.lu..de_ _ keywords : fixed point iteration , picard iteration , transmission problem , dirichlet - neumann iteration , termination criteria _ .
And you have already written the first three sentences of the full article: the general problem that this article is about is the following : consider a nonlinear equation system and an outer iteration method to solve it that consists of solving a subproblem at each step using a second , inner iteration method .
now we want to answer the following question : how can we efficiently control the iteration error of the outer iteration method ? or otherwise put : how accurate do we need to solve the inner systems to obtain a certain iteration error for the outer nonlinear equation ? for the case of the outer iteration being newton s method , this problem has been successfully solved . the inner problem is a linear system and the concept of an inexact newton s method was introduced in @xcite . there
, at each newton step the inner iteration is terminated when a relative tolerance criterion in the linear residual is satisfied ..
Please generate the next two sentences of the article | based on this , it is possible to give conditions on the sequence of relative tolerances to obtain linear , superlinear or quadratic convergence of the inexact newton s method . essentially , the sequence of tolerances has to converge to zero fast enough as the newton scheme progresses and then quadratic convergence is obtained .
following up , a strategy that has this property and leads to a very efficient scheme was suggested in @xcite . |
7,197 | Suppose that you have an abstract for a scientific paper: this paper describes the design process for developing a nonlinear model predictive controller for fault tolerant flight control . after examining and implementing a number of numerical techniques
, this paper identifies pseudospectral discretisation as the most suitable for this design . applying the controller to a 2d robot model shows that the nonlinear controller performs much better than the linear controller , especially in the closed loop scenario . assuming fault detection information , applying the technique to the longitudinal motion of a generic aircraft model shows the design to be eminently suitable for flight control .
keywords : nonlinear model predictive control , pseudospectral , optimal control , 2d robot , flight control .
And you have already written the first three sentences of the full article: most research on fault tolerant control sits within the context of large manned aircraft . with regards to unmanned aerial vehicles ( uavs )
, the majority of the literature describes the application of fault tolerant control ( ftc ) to rotorcraft rather than fixed wing aircraft . in this paper
we develop a nonlinear model predictive control ( nmpc ) based controller for a fixed wing aircraft model suitable for the purposes of fault.
Please generate the next two sentences of the article | tolerant flight control .
the controller is first tested and analysed on a lower order 2d robot model . then assuming that fault information is available we successfully demonstrate for the first time the use of an nmpc based fault tolerant flight control system for a fixed wing aircraft . |
7,198 | Suppose that you have an abstract for a scientific paper: we present x - ray spectral analysis of the accreting young star tw hydrae from a 489 ks observation using the _ chandra _ high energy transmission grating .
the spectrum provides a rich set of diagnostics for electron temperature @xmath0 , electron density @xmath1 , hydrogen column density @xmath2 , relative elemental abundances and velocities and reveals its source in 3 distinct regions of the stellar atmosphere : the stellar corona , the accretion shock , and a very large extended volume of warm postshock plasma .
the presence of , , and emission lines in the spectrum requires coronal structures at @xmath310 mk .
lower temperature lines ( e.g. , from , , and ) formed at 2.5 mk appear more consistent with emission from an accretion shock . he - like line ratio diagnostics indicate that @xmath4mk and @xmath5 @xmath6 in the shock .
these values agree well with standard magnetic accretion models .
however , the _ chandra _ observations significantly diverge from current model predictions for the postshock plasma .
this gas is expected to cool radiatively , producing as it flows into an increasingly dense stellar atmosphere .
surprisingly , indicates @xmath7 @xmath6 , five times lower than @xmath1 in the accretion shock itself , and @xmath3 seven times lower than the model prediction .
we estimate that the postshock region producing has roughly 300 times larger volume , and 30 times more emitting mass than the shock itself .
apparently , the shocked plasma heats the surrounding stellar atmosphere to soft x - ray emitting temperatures and supplies this material to nearby large magnetic structures which may be closed magnetic loops or open magnetic field leading to mass outflow .
our model explains the soft x - ray excess found in many accreting systems as well as the failure to observe high @xmath1 signatures in some stars .
such accretion - fed coronae may be ubiquitous in the atmospheres of accreting young stars . .
And you have already written the first three sentences of the full article: low mass stars in star - forming regions produce strong x - ray emission from coronal magnetic activity , as evidenced by high temperature ( @xmath310 mk ) emission from flares and active regions ( feigelson & montmerle 1999 ; gagn et al .
2004 ; preibisch et al .
the role of accretion in the production of x - rays from young stars is less well understood ..
Please generate the next two sentences of the article | magnetic structures on stars can extend all the way to the inner accretion disk , as suggested from models of decaying stellar flares ( favata et al .
extended x - ray emission from jets also occurs , as observed in dg tau , a system oriented so that the circumstellar disk plane aligns with our line of sight ( gdel et al . |
7,199 | Suppose that you have an abstract for a scientific paper: we developed a new method of determination of the size of the broad emission - line region ( blr ) in active galactic nuclei .
this method relates the radius of the broad - line region of agn to the soft x - ray luminosity and spectral index . comparing the blr distances calculated from our model to the blr distances determined by reverberation mapping
shows that our scaling law agrees with the @xmath0 empirical relation .
here we investigate a complimentary method of estimating the blr distance - based on the keplerian broadening of the emission lines and the central mass estimated from x - ray variability . .
And you have already written the first three sentences of the full article: recent results from reverberation - mapping of the broad emission - line regions ( blr ) in agn indicate that the blr distance from the central radiation source roughly scales as @xmath1 ( peterson 1995 ) .
recently we have elaborated a different method for estimating the blr distance , using the emission - line photoionization model . in order to explain the anticorrelation between the h@xmath2 line width and the soft x - ray spectral slope in narrow - line seyfert 1 galaxies ( nls1 ) ( boller , brandt and fink 1996 ; wang , brinkmann and bergeron 1996 ) , wandel and boller ( 1997 ) showed that a steeper spectrum would produce a blr at a relatively larger distance from the central source ,
so the keplerian velocity is lower ..
Please generate the next two sentences of the article | this modified blr distance calculated from the photoionization relation agrees well with the reverberation distance ( wandel 1996 ; 1997 ) . in this work
we connect this model to the r(blr ) @xmath3 relation by independently determining the central mass from the x - ray variability . |
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