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9,300 | Suppose that you have an abstract for a scientific paper: it is argued that the magnetic behavior of sr@xmath0mnmoo@xmath1 is determined by the existence of two total energy minima corresponding to the metallic ferromagnetic and insulating antiferromagnetic states , which may be nearly degenerate depending on the magnitude of the breathing distortion .
+ _ pacs : _ 71.20.be ; 71.70.gm ; 72.25.ba ; 75.30.et _ keywords : _ ordered double perovskites , double exchange and superexchange interactions , electronic structure calculations , lattice distortion * on the competition between ferromagnetic and antiferromagnetic states in sr@xmath0mnmoo@xmath1 * + i. v. solovyev + _ tokura spin superstructure project ( sss ) , + erato japan science and technology corporation , + c / o national institute of advanced industrial science and technology , + aist tsukuba central 4 , 1 - 1 - 1 higashi , tsukuba , ibaraki 305 - 8562 , japan _ .
And you have already written the first three sentences of the full article: recently , the ordered double perovskites sr@xmath0@xmath2@xmath3o@xmath1 ( @xmath2 being the magnetic @xmath4 element , and @xmath3 being the @xmath5 or @xmath6 element ) have attracted a great deal of attention .
the interest to these systems was spurred on by large intergrain - tunneling magnetoresistance observed at room temperature in sr@xmath0femoo@xmath1 and sr@xmath0fereo@xmath1 @xcite , which opens wide perspectives for technological applications . on the contrary , sr@xmath0mnmoo@xmath1 remains paramagnetic down to the very low temperature @xcite .
the magnetic susceptibility of sr@xmath0mnmoo@xmath1 obeys the curie - weiss law with fairly large effective moment . however , there is something that prevents formation of the long - range magnetic order in this material ( a similar situation occurs in double - layer manganites la@xmath7sr@xmath8mn@xmath0o@xmath9 around @xmath10@xmath11@xmath12 @xcite ) . in this work.
Please generate the next two sentences of the article | we argue that such a behavior may be due to the competition between ferromagnetic ( fm ) and type - ii antiferromagnetic ( afm ) phases .
the main idea of this work is to complement the standard total energy calculations with the analysis of inter - atomic magnetic interactions in the collinear magnetic state characterized by the directions @xmath13 of the spin magnetic moments . |
9,301 | Suppose that you have an abstract for a scientific paper: quantum dot hybrid qubits formed from three electrons in double quantum dots represent a promising compromise between high speed and simple fabrication for solid state implementations of single qubit and two qubits quantum logic ports .
we derive the schrieffer - wolff effective hamiltonian that describes in a simple and intuitive way the qubit by combining a hubbard - like model with a projector operator method . as a result ,
the hubbard - like hamiltonian is transformed in an equivalent expression in terms of the exchange coupling interactions between pairs of electrons .
the effective hamiltonian is exploited to derive the dynamical behaviour of the system and its eigenstates on the bloch sphere to generate qubits operation for quantum logic ports . a realistic implementation in silicon and the coupling of the qubit with a detector
are discussed . .
And you have already written the first three sentences of the full article: dynamics of the quantum dot hybrid qubit is obtained from the schrieffer - wolff transformed effective hamiltonian in terms of effective exchange coupling interaction between pairs of electrons .
spin dynamics in quantum dot have attracted wide attention in the scientific community both from experimental@xcite and theoretical@xcite point of view because of their long coherence times and potential scaling @xcite .
several architectures have been proposed based on single @xcite , double @xcite and triple @xcite quantum dot , later implemented in gaas @xcite , si @xcite and insb @xcite nanostructures . in view of creating an architecture.
Please generate the next two sentences of the article | capable to assure the best compromise among fabrication , tunability , fast gate operations of one and two qubits , manipulability and scalability , hybrid qubits have been recently proposed @xcite .
they consist of a double quantum dot with three electrons distributed during the operations between the two quantum dots , with at least one electron in each . |
9,302 | Suppose that you have an abstract for a scientific paper: when using hartree - fock ( hf ) trial wave functions in quantum monte carlo calculations , one faces , in case of hf instabilities , the hf symmetry dilemma in choosing between the symmetry - adapted solution of higher hf energy and symmetry - broken solutions of lower hf energies . in this work , we have examined the hf symmetry dilemma in hydrogen rings which present singlet instabilities for sufficiently large rings .
we have found that the symmetry - adapted hf wave function gives a lower energy both in variational monte carlo and in fixed - node diffusion monte carlo .
this indicates that the symmetry - adapted wave function has more accurate nodes than the symmetry - broken wave functions , and thus suggests that spatial symmetry is an important criterion for selecting good trial wave functions . .
And you have already written the first three sentences of the full article: it is well known that the symmetry - adapted solution of the nonlinear hartree - fock ( hf ) equations of an electronic system is sometimes unstable .
an unstable solution corresponds to a saddle point of the energy as a function of the orbital parameters , and breaking of space and/or spin symmetries of the wave function then necessarily leads to one or several lower - energy hf solutions .
the stability conditions of the hf equations were first formulated by thouless @xcite , and the different instabilities were first categorized by iek and paldus @xcite . for closed - shell systems.
Please generate the next two sentences of the article | , one may encounter `` singlet instabilities '' when only spatial symmetry is broken , and `` triplet ( or nonsinglet ) instabilities '' when spin symmetry is also broken .
there is thus a symmetry dilemma @xcite in choosing between the symmetry - adapted wave function of higher hf energy and a symmetry - broken wave function of lower hf energy , in particular as a reference for a post - hartree - fock calculation . a clear example is provided by closed - shell hydrogen rings h@xmath0 with equal bond lengths @xcite ( see , also , ref . ) . |
9,303 | Suppose that you have an abstract for a scientific paper: we develop a statistical estimator to infer the redshift probability distribution of a photometric sample of galaxies from its angular cross - correlation in redshift bins with an overlapping spectroscopic sample .
this estimator is a minimum - variance weighted quadratic function of the data : a _
quadratic estimator_. this extends and modifies the methodology presented by @xcite .
the derived source redshift distribution is degenerate with the source galaxy bias , which must be constrained via additional assumptions .
we apply this estimator to constrain source galaxy redshift distributions in the kilo - degree imaging survey through cross - correlation with the spectroscopic 2-degree field lensing survey , presenting results first as a binned step - wise distribution in the range @xmath0 , and then building a continuous distribution using a gaussian process model .
we demonstrate the robustness of our methodology using mock catalogues constructed from n - body simulations , and comparisons with other techniques for inferring the redshift distribution
. surveys , cosmology : observation , large scale structure of the universe .
And you have already written the first three sentences of the full article: current and forthcoming photometric surveys aim to image a significant fraction of the sky . in doing so
, they will obtain the angular positions of millions of galaxies . realizing the scientific potential of these surveys requires an estimate of the _ redshift distribution of the galaxies _ , which is important for connecting measurements such as tomographic weak lensing @xcite , the integrated sachs - wolfe effect and angular power spectra to the underlying cosmological model . in this work
we investigate a method to measure galaxy redshift distributions using angular cross - correlations with an overlapping spectroscopic sample ..
Please generate the next two sentences of the article | we outline the approach as follows .
consider two galaxy datasets : a spectroscopic sample with a known redshift distribution , and a photometric sample with an unknown redshift distribution . |
9,304 | Suppose that you have an abstract for a scientific paper: this paper presents a new algorithm for online estimation of a sequence of homographies applicable to image sequences obtained from robotic vehicles equipped with vision sensors .
the approach taken exploits the underlying special linear group structure of the set of homographies along with gyroscope measurements and direct point - feature correspondences between images to develop temporal filter for the homography estimate .
theoretical analysis and experimental results are provided to demonstrate the robustness of the proposed algorithm .
the experimental results show excellent performance even in the case of very fast camera motion ( relative to frame rate ) , severe occlusion , and in the presence of specular reflections . .
And you have already written the first three sentences of the full article: when a robotic vehicle equipped with a vision sensor is manoeuvering in a built environment , consisting primarily of planar or near planar surfaces , then the nature of the environment can be exploited in the vision processing algorithms .
different images of the same planar surface are related by homography mappings , and homographies have been used extensively in robotic applications as a vision primitive .
homography - based algorithms have been used for estimation of the rigid - body pose of a vehicle equipped with a camera @xcite ..
Please generate the next two sentences of the article | navigation of robotic vehicles has been developed based on homography sequences @xcite and one of the most successful visual servo control paradigms uses homographies @xcite .
homography - based methods are particularly well suited to navigation of unmanned aerial vehicles @xcite where the ground terrain is viewed from a distance and the relief of surface features is negligible compared to the vehicles distance from the scene . |
9,305 | Suppose that you have an abstract for a scientific paper: we present a set of five axioms for fairness measures in resource allocation .
a family of fairness measures satisfying the axioms is constructed .
well - known notions such as @xmath0fairness , jain s index , and entropy are shown to be special cases .
properties of fairness measures satisfying the axioms are proven , including schur - concavity . among the engineering implications
is a generalized jain s index that tunes the resolution of the fairness measure , a new understanding of @xmath0-fair utility functions , and an interpretation of `` larger @xmath0 is more fair '' .
we also construct an alternative set of four axioms to capture efficiency objectives and feasibility constraints . .
And you have already written the first three sentences of the full article: given a vector @xmath1 , where @xmath2 is the resource allocated to user @xmath3 , _ how fair _ is it ?
one approach to quantify the degree of fairness associated with @xmath4 is through a fairness measure , which is a function @xmath5 that maps @xmath4 into a real number .
various fairness measures have been proposed throughout the years , e.g. , in @xcite ..
Please generate the next two sentences of the article | these range from simple ones , e.g. , the ratio between the smallest and the largest entries of @xmath4 , to more sophisticated functions , e.g. , jain s index and the entropy function .
some of these fairness measures map @xmath4 to normalized ranges between 0 and 1 , where 0 denotes the minimum fairness , 1 denotes the maximum fairness , often corresponding to an @xmath4 where all @xmath2 are the same , and a larger value indicate more fairness . for example , min - max ratio @xcite is given by the maximum ratio of any two user s resource allocation , while jain s index @xcite computes a normalized square mean . |
9,306 | Suppose that you have an abstract for a scientific paper: the n206 supernova remnant ( snr ) in the large magellanic cloud ( lmc ) has long been considered a prototypical mixed morphology " snr .
recent observations , however , have added a new twist to this familiar plot : an elongated , radially - oriented radio feature seen in projection against the snr face . utilizing the high resolution and sensitivity available with the _ hubble space telescope _ , _ chandra _ , and _ xmm - newton _ , we have obtained optical emission - line images and spatially resolved x - ray spectral maps for this intriguing snr .
our findings present the snr itself as a remnant in the mid to late stages of its evolution .
x - ray emission associated with the radio linear feature " strongly suggests it to be a pulsar - wind nebula ( pwn ) .
a small x - ray knot is discovered at the outer tip of this feature .
the feature s elongated morphology and the surrounding wedge - shaped x - ray enhancement strongly suggest a bow - shock pwn structure . .
And you have already written the first three sentences of the full article: the supernova remnant ( snr ) b [email protected] lies to the north and east of the region lh@xmath1 120-n206 in the large magellanic cloud ( lmc ) .
the snr was first identified in radio by @xcite , who referred to it simply as n206 .
although this is more properly the name of the larger complex , for simplicity we shall use the same notation in the following discussion . h@xmath1 images of n206 obtained from the magellanic cloud emission - line survey @xcite show largely shell - like emission , with complex filamentary structure along the limb.
Please generate the next two sentences of the article | @xcite noted that these features were in sharp contrast to the x - ray emission as observed by _
rosat _ , which shows the x - ray emission brightening toward the center of the remnant . |
9,307 | Suppose that you have an abstract for a scientific paper: i describe renewed efforts to establish a string description of large @xmath0 qcd by summing large `` fishnet '' diagrams
. earlier work on fishnets indicated that the usual relativistic ( zero thickness ) string theory can arise at strong t hooft coupling , at best yielding a highly idealized description , which fails to incorporate such salient features of continuum qcd as asymptotic freedom and point - like constituents .
the recently conjectured ads / cft correspondence is compatible with such limitations because it also gives a simple picture of large @xmath0 gauge theory only at strong coupling . in order to better understand how string theory could emerge from large @xmath0 qcd at strong coupling , klaus bering , joel rozowsky , and
i have developed an improved implementation of my effort of the late seventies to digitize the planar diagrams of large @xmath0 light - cone quantized qcd by discretizing both @xmath1 and @xmath2 .
this discretization allows a strong coupling limit of the sum of planar diagrams to be defined and studied .
it also provides a natural framework to explore the possible dual relationship between qcd in light - cone gauge and string theory quantized on the light - cone .
ufift - hep-00 - 9 + hep - th/0004129 1.5 cm * string from large n gauge fields + via graph summation on a @xmath1 - @xmath2 lattice * 2.cm charles b. thorn 0.5 cm _ institute for fundamental theory + department of physics , university of florida , gainesville , fl 32611 _ ( ) .5 cm .
And you have already written the first three sentences of the full article: it has long been thought that t hooft s @xmath3 limit @xcite of @xmath4 gauge theory might be usefully described by some sort of string theory .
however , there is an apparently devastating argument , that this `` qcd string '' ( a.k.a . a tower of glueballs ) is _ not _ fundamental string ( of `` string theory '' ) : the graviton appears in the spectrum of the latter , contradicting the well - known folk theorem @xcite forbidding massless spin 2 bound states in a poincar invariant quantum field theory .
a way to evade this argument has been shown by the conjectured equivalence between classical iib superstring theory on an ads@xmath5 background and @xmath6 supersymmetric @xmath7 yang - mills on flat 4 dimensional minkowski space - time @xcite ..
Please generate the next two sentences of the article | the point is that in this example the graviton lives in 5 space - time dimensions and the flat space - time global symmetry ( poincar(3,1 ) ) is only a subgroup of poincar(4,1 ) , which is realized locally , not globally .
thus the `` massless '' 5 dimensional graviton is a composite of the quanta of a flat - space quantum field theory in 4 dimensional space - time . |
9,308 | Suppose that you have an abstract for a scientific paper: we report the crystal structure and highly - anisotropic magnetic , transport and thermal properties of an exceptionally good single crystal of u(ru@xmath0rh@xmath1)@xmath2si@xmath2 prepared using a modified czochralski method .
our study , that also includes neutron diffraction results , shows all the heavy - fermion signatures of pristine uru@xmath2si@xmath2 , however , the superconductivity , hidden order and remanent weak antiferromagnetic orders are absent . instead , the ground state of the doped system can be classified as a spin liquid that preserves the heavy - fermion character .
u(ru@xmath0rh@xmath1)@xmath2si@xmath2 exhibits a short - range magnetic order distinguished by reflections of a lorentzian profile at * _ q@xmath3 _ * = ( @xmath4 @xmath4 @xmath4 ) positions that disappear above @xmath5 15 k. the short - range order seems to be a precursor of a long - range magnetic order that occurs with higher rh concentration . we indicate that these short - range fluctuations involve , at least partially , inelastic scattering processes . .
And you have already written the first three sentences of the full article: uru@xmath2si@xmath2 is a heavy fermion compound ( space group @xmath6 ) , @xmath7 = 180 mj k@xmath8mole@xmath9 , where superconductivity ( sc ) below the superconducting transition at t@xmath10 = 1.5 k coexists with yet unidentified order parameter that is linked to a remanent antiferromagnetism ( afm ) @xcite , both appearing below t@xmath11 = 17.5 k ( for a review see @xcite ) .
the weak afm order is characterized by a propagation vector * _ q@xmath12 _ * = ( 1 0 0 ) with the ordered dipolar moments pointing along the @xmath13-axis and very small , ( 0.01 - 0.03 @xmath14 @xcite ) . in order to explain the clear anomalies in temperature dependencies of properties , notably the large entropy connected with the transition
, an unconventional phase change is postulated@xcite ..
Please generate the next two sentences of the article | it is generally accepted that this afm order is not intrinsic but parasitic .
accordingly , this new state is called hidden order ( ho ) and is one of the most addressed topics in heavy - fermion physics research@xcite . near the ho state , different phases can be induced by external perturbations like pressure , magnetic field or substitution . a moderate pressure converts the ho phase @xcite into a static long - range antiferromagnetic ( af ) |
9,309 | Suppose that you have an abstract for a scientific paper: chaotic internal degrees of freedom of a molecule can act as noise and affect the diffusion of the molecule on a substrate .
a separation of time scales between the fast internal dynamics and the slow motion of the centre of mass on the substrate makes it possible to directly link chaos to diffusion .
we discuss the conditions under which this is possible , and show that in simple atomistic models with pair - wise harmonic potentials , strong chaos can arise through the geometry . using molecular - dynamics simulations , we demonstrate that a realistic model of benzene is indeed chaotic , and that the internal chaos affects the diffusion on a graphite substrate . .
And you have already written the first three sentences of the full article: diffusion is always related to noise in some way . in the case of brownian motion , and in most studies of diffusion ,
the noise is thermal in origin .
thermal noise is , in principle , generated by a deterministic many - particle system , but noise can also be generated by smaller deterministic systems if they possess the right dynamical properties . in the case of diffusion of large molecules adsorbed on a surface , the internal dynamics of the molecules can be such a source of noise ..
Please generate the next two sentences of the article | experimental @xcite and numerical @xcite evidence exists demonstrating that rotational and other internal degrees of freedom affect the diffusion . in some cases clusters of molecules have been shown to diffuse more rapidly than single particles @xcite .
all this suggests that the internal degrees of freedom can play an important role . |
9,310 | Suppose that you have an abstract for a scientific paper: we investigate coupled identical phase oscillators with scale - free distribution of coupling strength . it is shown that partially locked states can occur due to the inhomogeneity in coupling and some properties of the coupling function .
various quantities of the partially locked states are computed through a self - consistency argument and the values show good agreement with simulation results . .
And you have already written the first three sentences of the full article: synchronization of coupled oscillators is important and has been widely studied in variety of systems from physics , chemistry and biology @xcite .
partially locked states are states of imperfect synchronization with locked subpopulation and drifting subpopulation , and have been observed in coupled oscillators with distributed intrinsic frequencies @xcite .
the formation of locked subpopulation with the increase of the coupling strength is one of the explanations for the transition between asynchronous states and synchronous states . in these cases ,.
Please generate the next two sentences of the article | partial locking is due to the inhomogeneity in intrinsic frequencies .
for some oscillators , the coupling strength is strong enough to make the oscillators locked to the coupling force by overcoming the desynchronizing effect of frequency difference , but for others it is not strong enough and they drift . however , there can be desynchronizing factors other than ones intrinsic to uncoupled oscillators . |
9,311 | Suppose that you have an abstract for a scientific paper: we calculate accurate solar models and report the detailed time dependences of important solar quantities .
we use helioseismology to constrain the luminosity evolution of the sun and report the discovery of semi - convection in evolved solar models that include diffusion .
in addition , we compare the computed sound speeds with the results of @xmath0-mode observations by bison , golf , gong , lowl , and mdi instruments .
we contrast the neutrino predictions from a set of eight standard - like solar models and four deviant ( or deficient ) solar models with the results of solar neutrino experiments . for solar neutrino and for helioseismological applications ,
we present present - epoch numerical tabulations of characteristics of the standard solar model as a function of solar radius , including the principal physical and composition variables , sound speeds , neutrino fluxes , and functions needed for calculating solar neutrino oscillations . .
And you have already written the first three sentences of the full article: why are new calculations of standard solar models of interest ? after all , solar models have been used to calculate neutrino fluxes since 1962 ( bahcall , fowler , iben , & sears 1963 ) and solar atmospheres have been used to calculate p - mode oscillation frequencies since 1970 ( ulrich 1970 ; leibacher & stein 1971 ) . over the past four decades , the accuracy with which solar models are calculated has been steadily refined as the result of increased observational and experimental information about the input parameters ( such as nuclear reaction rates and the surface of abundances of different elements ) , more accurate calculations of constituent quantities ( such as radiative opacity and equation of state ) , the inclusion of new physical effects ( such as element diffusion ) , and the development of faster computers and more precise stellar evolution codes .
solar models nevertheless remain at the frontiers of two different scientific disciplines , solar neutrino studies and helioseismology . in an era in which many major laboratory studies are underway to study neutrino oscillations with the aid of very long baselines , @xmath1 km , between accelerator and detector ,
solar neutrinos have a natural advantage , with a baseline of @xmath2 km ( pontecorvo 1968 ) ..
Please generate the next two sentences of the article | in addition , solar neutrinos provide unique opportunities for studying the effects of matter upon neutrino propagation , the so - called msw effect ( wolfenstein 1978 ; mikheyev & smirnov 1985 ) , since on their way to terrestrial detectors they pass through large amounts of matter in the sun and , at night , also in the earth .
the connection with ongoing solar neutrino research imposes special requirements on authors carrying out the most detailed solar modeling . |
9,312 | Suppose that you have an abstract for a scientific paper: if a @xmath0-ray line is observed in the near future , it will be important to determine what kind of dark matter ( dm ) particle could be at its origin .
we investigate the possibility that the @xmath0-ray line would be induced by a slow dm particle decay associated to the fact that the dm particle would not be absolutely neutral .
a `` millicharge '' for the dm particle can be induced in various ways , in particular from a kinetic mixing interaction or through the stueckelberg mechanism .
we show that such a scenario could lead in specific cases to an observable @xmath0-ray line .
this possibility can be considered in a systematic model - independent way , by writing down the corresponding effective theory .
this allows for a multi - channel analysis , giving in particular upper bounds on the intensity of the associated @xmath0-ray line from cosmic rays emission .
our analysis includes the possibility that in the two - body decay the photon is accompanied with a neutrino .
we show that , given the stringent constraints which hold on the millicharge of the neutrinos , this is not an option , except if the dm particle mass lies in the very light kev - mev range , allowing for a possibility of explanation of the recently claimed , yet to be confirmed , @xmath1 kev x - ray line . .
And you have already written the first three sentences of the full article: one of the most promising `` smoking - gun '' signals for establishing the existence of the dark matter particle is the possible observation of a sharp cosmic @xmath0-ray line from dark matter annihilation or decay @xcite .
the forthcoming cherenkov telescopes @xcite , the current fermi large area telescope @xcite and the hess instrument @xcite will allow to probe this possibility with further sensitivity . if such a signal is observed in the near future , the question of the identification of the dm particle that could have caused it will become crucial . such a signal could be induced through annihilation , coannihilation or decay . for all these scenarios , it is generally assumed that the photon is emitted through the loop of a charged particle . beside this general class of models , there exist other ways along which dm could emit monochromatic photons .
one possibility consists in assuming that the @xmath0-ray line is due to a @xmath2 chern - simons interaction @xcite ..
Please generate the next two sentences of the article | another possibility , much less studied , would be to consider a photon directly emitted by the dm particle .
this is a priori perfectly possible if dm is not exactly neutral , but is millicharged . for an annihilation such |
9,313 | Suppose that you have an abstract for a scientific paper: in this talk i discuss the role of heavy quarks in new physics searches with tau leptons .
i focus on new physics effects associated to the scalar sector which are naturally enhanced for the heaviest fermions due to the large hierarchy of the fermion masses .
i will discuss two topics within this context : lepton flavour violation in the @xmath0 ( @xmath1 ) sector and violations of lepton universality in tauonic @xmath2 decays .
tau lepton , lepton flavour violation , lepton universality .
And you have already written the first three sentences of the full article: heavy quarks @xmath3 play an important role in many searches for physics beyond the standard model ( sm ) with tau ( @xmath4 ) leptons .
i will focus here on the possibility of new physics effects associated to the scalar sector for which a connection between heavy quarks and the tau lepton is established due to their large mass .
the discovery of a sm - like higgs boson by the atlas and cms collaborations seems to confirm that a scalar sector is responsible for the breaking of the ew gauge symmetry @xcite ..
Please generate the next two sentences of the article | the strong hierarchy of the fermion mass spectrum implies that the sm higgs couplings to light quarks and leptons are very suppressed .
the heaviest fermions offer then a unique place where exotic effects associated to the higgs sector can be sizable due to their larger masses . |
9,314 | Suppose that you have an abstract for a scientific paper: we investigate the clustering properties of 13 qso lines of sight in flat space , with average redshifts from @xmath0 to 4 .
we estimate the 1d power spectrum and the integral density of neighbours , and discuss their variation with respect to redshift and column density . we compare the results with standard cdm models , and estimate the power spectrum of lyman-@xmath1 clustering as a function both of redshift and column density .
we find that @xmath2 ) there is no significant periodicity or characteristic scale ; @xmath3 ) the clustering depends both on column density and redshift ; @xmath4 ) the clustering increases linearly only if at the same time the hi column density decreases strongly with redshift .
the results remain qualitatively the same assuming an open cosmological model .
2@xmath5 @xmath6 hsd epsf.tex .
And you have already written the first three sentences of the full article: as new and deeper galaxy redshift surveys are being completed , a definite picture of the local galaxy distribution is slowly emerging .
this distribution is characterized by large voids surrounded by sheets of clustered matter ( see e.g. el - ad et al . 1996a , 1997 ) , and can be well quantified by statistical descriptors like the power spectrum ( see e.g. park et al .
1994 , tadros & efstathiou 1995 , tadros & efstathiou 1996 , lin et al ..
Please generate the next two sentences of the article | 1996 ) . in a few years , surveys like the sloan digital sky survey ( loveday 1996 ) and the two degree field redshift survey ( colless 1998 , maddox 1998 ) will extend our knowledge of the clustering of the luminous matter by at least a factor of ten both in depth and coverage
. however , mapping the luminous galaxies is clearly not enough to fully understand the history and geography of our universe . |
9,315 | Suppose that you have an abstract for a scientific paper: we study landau - zener - stuckelberg ( lzs ) interferometry in multilevel systems coupled to an ohmic quantum bath .
we consider the case of superconducting flux qubits driven by a dc+ac magnetic fields , but our results can apply to other similar systems .
we find a dynamic transition manifested by a symmetry change in the structure of the lzs interference pattern , plotted as a function of ac amplitude and dc detuning .
the dynamic transition is from a lzs pattern with nearly symmetric multiphoton resonances to antisymmetric multiphoton resonances at long times ( above the relaxation time ) .
we also show that the presence of a resonant mode in the quantum bath can impede the dynamic transition when the resonant frequency is of the order of the qubit gap .
our results are obtained by a numerical calculation of the finite time and the asymptotic stationary population of the qubit states , using the floquet - markov approach to solve a realistic model of the flux qubit considering up to 10 energy levels . .
And you have already written the first three sentences of the full article: in recent years , the experimental realization of landau - zener - stckelberg ( lzs ) interferometry@xcite in several systems has emerged as a tool to study quantum coherence under strong driving .
lzs interferometry is realized in two - level systems ( tls ) which are driven with a time periodic force .
the periodic sweeps through an avoided crossing in the energy level spectrum result in successive landau - zener transitions ..
Please generate the next two sentences of the article | the accumulated phase between these repeated tunneling events gives place to constructive or destructive interferences , depending on the driving amplitude and the detuning from the avoided crossing .
these lzs interferences have been observed in a variety of quantum systems , such as rydberg atoms,@xcite superconducting qubits,@xcite ultracold molecular gases,@xcite quantum dot devices,@xcite single spins in nitrogen vacancy centers in diamond,@xcite nanomechanical circuits,@xcite and ultracold atoms in accelerated optical lattices.@xcite several other related experimental and theoretical works have studied lzs interferometry in systems under different shapes of periodic driving,@xcite in two coupled qubits,@xcite in optomechanical systems,@xcite and the effect of a geometric phase.@xcite furthermore , experiments in superconducting flux qubits under strong driving have allowed to extend lzs interferometry beyond two levels.@xcite in this later case , the multi - level structure of the flux qubit , with several different avoided crossings in the energy spectrum , exhibited a series of diamond - like interference patterns as a function of dc flux detuning and microwave amplitude.@xcite driven two - level systems have been extensively studied theoretically in the past . under strong time - periodic driving fields , phenomena such as coherent destruction of tunneling ( cdt ) @xcite and multiphoton resonances @xcite |
9,316 | Suppose that you have an abstract for a scientific paper: we consider the effects of non - constant star formation histories ( sfhs ) on h@xmath0 and galex far ultra - violet ( fuv ) star formation rate ( sfr ) indicators . under the assumption of a fully populated chabrier imf
, we compare the distribution of h@xmath0-to - fuv flux ratios from @xmath1 1500 simple , periodic model sfhs with observations of 185 galaxies from the _ spitzer _ local volume legacy survey .
we find a set of sfh models that are well matched to the data , such that more massive galaxies are best characterized by nearly constant sfhs , while low mass systems experience bursts amplitudes of @xmath1 30 ( i.e. , an increase in the sfr by a factor of 30 over the sfr during the inter - burst period ) , burst durations of tens of myr , and periods of @xmath1 250 myr ; these sfhs are broadly consistent with the increased stochastic star formation expected in systems with lower sfrs .
we analyze the predicted temporal evolution of galaxy stellar mass , @xmath2-band surface brightness , h@xmath0-derived sfr , and blue luminosity , and find that they provide a reasonable match to observed flux distributions .
we find that our model sfhs are generally able to reproduce both the observed systematic decline and increased scatter in h@xmath0-to - fuv ratios toward low mass systems , without invoking other physical mechanisms .
we also compare our predictions with those from the integrated galactic imf theory with a constant sfr .
we find that while both predict a systematic decline in the observed ratios , only the time variable sfh models are capable of producing the observed population of low mass galaxies ( @xmath3 @xmath4 10@xmath5 m@xmath6 ) with normal h@xmath0-to - fuv ratios .
these results demonstrate that a variable imf alone has difficulty explaining the observed scatter in the h@xmath0-to - fuv ratios .
we conclude by considering the limitations of the model sfhs , and discuss the use of additional empirical constraints to improve future sfh modeling efforts . .
And you have already written the first three sentences of the full article: two of the most widely used tracers of recent star formation are the nebular h@xmath0 recombination line and the ultra - violet ( uv ) continuum .
the h@xmath0 arises from recombination of gas ionized by photons from massive stars ( @xmath7 15 m@xmath6 ) and is expected to be observed over the typical lifetimes of extremely massive stars ( @xmath4 5 myr ) .
the uv continuum is due to non - ionizing photospheric emission from stars with @xmath8 @xmath7 3 m@xmath6 , which have lifetimes @xmath4 300 myr . in tandem ,.
Please generate the next two sentences of the article | these two integrated tracers provide leverage on current and recent star formation in both nearby and distant galaxies ( see @xcite and references therein ) . in principle , observed h@xmath0 and uv luminosities should yield consistent measures of star formation . under the assumption of a constant sfh over a sufficiently long timeline ( e.g. , @xmath1 1 gyr ) ,
the expected ratio of h@xmath0 and uv star formation rates ( sfrs ) should be constant with respect to both time and environment ( see @xcite and references therein ) , assuming a fully populated and universal imf , solar metallicity , all lyman continuum photons ionize hydrogen , and with no attenuation due to dust . |
9,317 | Suppose that you have an abstract for a scientific paper: the optical interaction of light and matter is modeled as an oscillating dipole in a plane wave .
we analyze absorption , scattering and extinction for this system by the energy flow , which is depicted by streamlines of the poynting vector .
depending on the dissipative damping of the oscillator , the streamlines end up in the dipole . based on a graphical investigation of the streamlines ,
this represents the absorption cross section , and forms a far - field absorption aperture . in the near - field of the oscillator , a modification of the aperture is observed .
this scheme can be adapted to a single dipolar emitter , interacting with a light field . in the case of the absorption by a single atom , where the oscillator has a circular dipole characteristics , we model the energy flow and derive the apertures . .
And you have already written the first three sentences of the full article: one of the most fundamental processes in light - matter interaction is the attenuation of light by matter .
the introduced weakening of light is observed since ancient times . today , in modern nano - optics , it is possible to perform controlled experiments with single entities , i.e. single photons @xcite and single emitters @xcite .
the theoretical description of this optical interaction does not only address very fundamental questions , it also allows the optimization of the efficiency in light - matter interaction ..
Please generate the next two sentences of the article | the spectroscopy and optical research on single emitters in the past was engineered for optimal light - extraction strategies @xcite , such that e.g. a single molecule or a nano - crystal can be detected by fluorescence with a good signal to noise ratio .
but it was rarely optimized to achieve the most efficient excitation . for optical protocols , such as the quantum phase gate , or coherent microscopy schemes @xcite , |
9,318 | Suppose that you have an abstract for a scientific paper: a system @xmath0 of equivalence relations on a set @xmath1 is _ semirigid _ if only the identity and constant functions preserve all members of @xmath0 .
we construct semirigid systems of three equivalence relations .
our construction leads to the examples given by zdori in 1983 and to many others and also extends to some infinite cardinalities . as a consequence ,
we show that on every set of at most continuum cardinality distinct from @xmath2 and @xmath3 there exists a semirigid system of three equivalence relations . .
And you have already written the first three sentences of the full article: a _ binary relation _ on a set @xmath1 is a subset @xmath4 of the cartesian product @xmath5 .
we write @xmath6 instead of @xmath7 .
a map @xmath8 _ preserves _.
Please generate the next two sentences of the article | @xmath4 if @xmath9 for all @xmath10 .
a _ binary system _ on the set @xmath1 is a pair @xmath11 where each @xmath12 is a binary relation on @xmath1 . |
9,319 | Suppose that you have an abstract for a scientific paper: we explore the chiral transmission of electrons across graphene heterojunctions for electronic switching using gate geometry alone .
a sequence of gates is used to collimate and orthogonalize the chiral transmission lobes across multiple junctions , resulting in negligible overall current .
the resistance of the device is enhanced by several orders of magnitude by biasing the gates into the bipolar @xmath0 doping regime , as the on state in the near homogeneous @xmath1 regime remains highly conductive .
the mobility is preserved because the switching involves a transmission gap instead of a structural band - gap that would reduce the number of available channels of conduction . under certain conditions
this transmission gap is highly gate tunable , allowing a subthermal turn - on that beats the landauer bound on switching energy limiting present day digital electronics .
the intriguing possibilities of graphene derive from its exceptional electronic and material properties @xcite , in particular its photon - like bandstructure @xcite , ultrahigh mobility @xcite , pseudospin physics and improved 2-d electrostatics @xcite .
its switching ability , however , is compromised by the lack of a band - gap @xcite , while opening a gap structurally kills the available modes for conduction , degrading mobility @xcite .
this begs the question as to whether we can significantly modulate the conductivity of graphene without any structural distortion , thereby preserving its superior mobility and electron - hole symmetry . a way to do
this is to open a transmission gap that simply redirects the electrons , without actually shutting off the density of states .
the dual attributes that help graphene electrons in this regard are its photon like trajectories and chiral tunneling that makes the junction resistance strongly anisotropic , allowing redirection with gate geometry alone . in an earlier paper ,
@xcite we outlined how we can open a transmission gap by a tunnel barrier , angularly injecting....
And you have already written the first three sentences of the full article: _ the average tranmsission per mode : _ total transmission through a graphene heterojunction can be written as , @xmath74here we have used , angular spacing , @xmath75 , mode spacing @xmath76 and number of modes , @xmath77 . comparing with eq .
[ eq1 ] , we can write , @xmath78transmission through a single @xmath6 junction , where the potential changes smoothely from @xmath14 to @xmath15 over a distance @xmath16 is given by , @xmath79 ignoring the wave - function prefactor , this is valid for moderate gate split distance @xmath16 .
let us consider the @xmath11 for a single split junction and a tilted junction separately ..
Please generate the next two sentences of the article | @xmath81 with gate split . for an abrupt tilted junction , @xmath82 m\label{tilt_scaling}\end{aligned}\ ] ] due to
reduced density of modes at the higher angular region , @xmath83 is scaled with @xmath21 . |
9,320 | Suppose that you have an abstract for a scientific paper: it is argued that data from atmospheric and solar neutrino experiments point strongly to tri - maximal or bi - maximal lepton mixing . while ( ` optimised ' )
bi - maximal mixing gives an excellent _ a posteriori _ fit to the data , tri - maximal mixing is an _ a priori _ hypothesis , which is not excluded , taking account of terrestrial matter effects . .
And you have already written the first three sentences of the full article: threefold maximal mixing , ie . tri - maximal mixing , undeniably occupies a special place in the space of all @xmath0 mixings . in some weak basis the two non - commuting mass - matrices @xmath1 , @xmath2 ( @xmath3 ) may simultaneously be written @xcite as ` circulative ' matrices ( ` of degree zero ' ) @xcite : @xmath4 respectively invariant under monomial cyclic permutations ( ` circulation ' matrices @xcite ) of the form : @xmath5 ( @xmath6 , etc.)just as circulant matrices are invariant under simple cyclic permutations @xcite . the mass matrices eq .
1 are diagonalised by the ( eg . circulant ) unitary matrices @xmath7 and
@xmath8 : @xmath9 respectively , leading to threefold maximal mixing : @xmath10 where in all the above and in what follows @xmath11 and @xmath12 represent complex cube - roots of unity and the overhead ` bar ' denotes complex conjugation . after some rephasing of rows and columns the.
Please generate the next two sentences of the article | tri - maximal mixing matrix may be re - written : @xmath13 where the matrix in the parenthesis is identically the character table for the cyclic group @xmath14 ( group elements vs. irreducible representations ) . in
threefold maximal mixing the cp violation parameter @xmath15 is maximal ( @xmath16 ) and if no two neutrinos are degenerate in mass , cp and t violating asymmetries can approach @xmath17 . |
9,321 | Suppose that you have an abstract for a scientific paper: we have investigated the abundance anomalies of lithium for stars with planets in the temperature range of 56005900k reported by israelian and coworkers , as compared to 20 normal stars at the same temperature and metallicity ranges .
our result indicates a higher probability of lithium depletion for stars with planets in the main sequence stage .
it seems that stellar photospheric abundances of lithium in stars with planets may be somewhat affected by the presence of planets .
two possible mechanisms are considered to account for the lower li abundances of stars with planets .
one is related to the rotation - induced mixing due to the conservation of angular momentum by the protoplanetary disk , and the other is a shear instability triggered by planet migration .
these results provide new information on stellar evolution and the lithium evolution of the galaxy . .
And you have already written the first three sentences of the full article: since the first announcement of a planet orbiting a sun - like star , 51 peg , by @xcite , around 140 stars with planets ( swps ) have been reported .
the main properties of swps have been investigated by many works . among these , spectroscopic observations of most swps based on high - resolution and high signal - to - noise ratio spectra have been carried out .
all of these works indicate a high mean metallicity of swps relative to normal field stars ..
Please generate the next two sentences of the article | are there any other chemical signatures for swps ? there is no conclusive result on this issue , and only a few works have reported abundance anomalies in some elements .
for example , @xcite suggested a high [ c / fe ] ratio for swps as compared with the normal stars from @xcite . |
9,322 | Suppose that you have an abstract for a scientific paper: frozen parametric disorder can lead to appearance of sets of localized convective currents in an otherwise stable ( quiescent ) fluid layer heated from below .
these currents significantly influence the transport of an admixture ( or any other passive scalar ) along the layer .
when the molecular diffusivity of the admixture is small in comparison to the thermal one , which is quite typical in nature , disorder can enhance the effective ( eddy ) diffusivity by several orders of magnitude in comparison to the molecular diffusivity .
in this paper we study the effect of an imposed longitudinal advection on delocalization of convective currents , both numerically and analytically ; and report subsequent drastic boost of the effective diffusivity for weak advection .
_ special issue _ : article preparation , iop journals + disorder in operation conditions of a dynamic system is known to be able to play not only trivial destructive role , distorting the system behavior , but also constructive one , inducing certain degree of order and leading to various non - trivial effects : anderson localization @xcite , stochastic @xcite and coherence resonances @xcite , noise - induced synchronization @xcite , etc .
one of the most distinguished and fair effects is the anderson localization ( al ) , which is the localization of states in spatially extended linear systems subject to a frozen parametric disorder ( random spacial inhomogeneity of parameters ) .
al was first discovered and discussed for quantum systems @xcite .
later on , investigations were extended to diverse branches of semiclassical and classical physics : wave optics @xcite , acoustics @xcite , etc .
the phenomenon was comprehensively studied and well understood mathematically for the schrdinger equation and related mathematical models @xcite .
the role of nonlinearity in these models was addressed in literature as well ( e.g. , @xcite ) .
while extensively studied for conservative media , the localization phenomenon did....
And you have already written the first three sentences of the full article: in nature and technology , a broad variety of active media where pattern selection occurs is governed by kuramoto sivashinsky type equations . in the presence of an imposed advectional transport @xmath0 in the @xmath1-direction the modified kuramoto
sivashinsky equation reads @xmath2 this equation describes two - dimensional large - scale natural thermal convection in a horizontal fluid layer heated from below @xcite and is still valid for a turbulent fluid @xcite , a binary mixture at small lewis number @xcite , a porous layer saturated with a fluid @xcite , etc . in these fluid dynamical systems , except for the turbulent one @xcite , the plates bounding the layer should be nearly thermally insulating ( in comparison to the fluid ) for a large - scale convection to arise . in the problems mentioned , equation governs evolution of temperature perturbations @xmath3 which are nearly uniform along the vertical coordinate @xmath4 and determine fluid currents .
the origin of such a frequent occurrence of equation is its general validity , which may be argued as follows ..
Please generate the next two sentences of the article | basic laws in physics are conservation ones .
this often results in final governing equations having the form @xmath5+\nabla\!\cdot\![\mbox{flux of quantity}]=0 $ ] . |
9,323 | Suppose that you have an abstract for a scientific paper: is @xmath0 equal to @xmath1 ?
a. lightstone s decimal expansions yield an infinity of numbers in @xmath2 $ ] whose expansion starts with an unbounded number of repeated digits `` @xmath3 '' .
we present some non - standard thoughts on the ambiguity of the ellipsis , modeling the cognitive concept of _ generic limit _ of b. cornu and d. tall .
a choice of a non - standard hyperinteger @xmath4 specifies an @xmath4-infinite extended decimal string of @xmath3s , corresponding to an infinitesimally diminished hyperreal value . in our model , the student resistance to the unital evaluation of @xmath0 is directed against an unspoken and unacknowledged application of the standard part function , namely the stripping away of a ghost of an infinitesimal , to echo george berkeley .
so long as the number system has not been specified , the students hunch that @xmath0 can fall infinitesimally short of @xmath1 , can be justified in a mathematically rigorous fashion . supported by the israel science foundation ( grants no . 84/03 and 1294/06 ) and the bsf ( grant 2006393 ) ] .
And you have already written the first three sentences of the full article: student resistance to the evaluation of @xmath0 as the real number @xmath1 ( henceforth referred to as the _ unital evaluation _ ) has been widely discussed in the mathematics education literature .
it has been suggested that the source of such resistance lies in a psychological predisposition in favor of thinking of @xmath0 as a process , or iterated procedure , rather than the final outcome , see for instance d. tall s papers @xcite , @xcite , @xcite ( see also @xcite for another approach ) .
we propose an alternative model to explain such resistance , in the framework of non - standard analysis . from this point of view.
Please generate the next two sentences of the article | , the resistance is directed against an unspoken and unacknowledged application of the standard part function `` st '' ( see section [ ten ] , item [ 103 ] ) , namely the stripping away of a ghost of an infinitesimal , to echo george berkeley @xcite , implicit in unital evaluation : @xmath5{9tail.ps}}}\end{pmatrix } = 1.\ ] ] what is the significance of such fine ( indeed , infinitesimal ) districtions between @xmath0 and @xmath1 ? as this text is addressed to a wide audience , it may be worth recalling that _ dividing _ by the difference @xmath6 will only be possible if the latter is nonzero , a matter of immediate import for studying rates of change and calculating derivatives ( see section [ zoom ] ) .
the hyperreal approach to a certain extent vindicates the student resistance to education professionals toeing the standard line on unital evaluation : so long as the number system has not been specified , the students hunch that @xmath0 can fall infinitesimally short of @xmath1 , can be justified in a mathematically rigorous fashion . in section [ two ] , |
9,324 | Suppose that you have an abstract for a scientific paper: the configuration model was originally defined for undirected networks and has recently been extended to directed networks .
many empirical networks are however neither undirected nor completely directed , but instead usually partially directed meaning that certain edges are directed and others are undirected . in the paper
we define a configuration model for such networks where nodes have in- , out- , and undirected degrees that may be dependent . we prove conditions under which the resulting degree distributions converge to the intended degree distributions .
the new model is shown to better approximate several empirical networks compared to undirected and completely directed networks . .
And you have already written the first three sentences of the full article: graphs appear in many current applications . in social sciences
groups of people are often modeled by letting the vertices in the graph represent persons and edges represent the interactions or relationships between them .
edges can be directed or undirected , the later indicating a reciprocal relationship between the vertices ..
Please generate the next two sentences of the article | usually the graphs created from such datasets are simplifications of the original dataset .
one typical simplification is to allow only directed or only undirected edges . |
9,325 | Suppose that you have an abstract for a scientific paper: this work investigates the first correction to the equilibrium phase space distribution and its effects on spectra and elliptic flow in heavy ion collisions .
we show that the departure from equilibrium on the freezeout surface is the largest part of the viscous corrections to @xmath0 .
however , the momentum dependence of the departure from equilibrium is not known _ a priori _ , and it is probably not proportional to @xmath1 as has been assumed in hydrodynamic simulations . at high momentum in weakly coupled plasmas
it is determined by the rate of radiative energy loss and is proportional to @xmath2 .
the weaker @xmath3 dependence leads to straighter @xmath0 curves at the same value of viscosity .
further , the departure from equilibrium is generally species dependent .
a species dependent equilibration rate , with baryons equilibrating faster than mesons , can explain `` constituent quark scaling '' without invoking coalescence models . .
And you have already written the first three sentences of the full article: when two ultra - relativistic nuclei collide , they leave behind a region of high energy - density qcd matter , whose properties we would like to understand better .
the initial geometry of the qcd matter is set by the overlap region of the two colliding nuclei .
generally , the nuclei collide at finite impact parameter rather than head - on . in this case.
Please generate the next two sentences of the article | the initial geometry is not a disk , but is an `` almond shaped '' ellipse .
( the short and long axis of the initial almond are taken as the @xmath4 and @xmath5 axes respectively . ) |
9,326 | Suppose that you have an abstract for a scientific paper: supernova ( sn ) 2002ap in m74 was discovered on january 29 , 2002 .
being one of the nearest ( 10 mpc ) sn events in the last decades , and spectroscopically similar to the so - called `` hypernovae '' 1997ef and 1998bw , both possibly associated with gamma - ray bursts ( grbs ) , it is of great interest . shortly after its discovery , we launched an intensive photometric and spectroscopic monitoring campaign of this event , and here we report the results of the first month of observations .
we use our @xmath0 photometry to estimate the magnitudes at , and dates of , peak brightness .
our data suggest that this object reached its peak @xmath1band luminosity on feb . @xmath2
. based on its similarity to sn 1998bw , we estimate the range of possible dates for a grb that may have been associated with sn 2002ap .
we find that it may include dates outside the time frame for which all available gamma - ray data have been intensively scanned , according to recent reports .
the absolute magnitude at peak brightness of sn 2002ap ( m@xmath3 ) shows that it was significantly fainter than sn 1998bw , or normal type - ia sne , but similar to sn 1997ef .
our spectroscopic observations confirm that sn 2002ap is strikingly similar to sne 1998bw and 1997ef .
we briefly describe the spectral evolution of this object .
to assist other observers and to stimulate theoretical models , we make our entire data set publicly available in digital form .
= = = = = = = = # 1 # 1 # 1 # 1 @mathgroup@group @mathgroup@normal@groupeurmn @mathgroup@bold@groupeurbn @mathgroup@group @mathgroup@normal@groupmsamn @mathgroup@bold@groupmsamn = `` 019 = ' ' 016 = `` 040 = ' ' 336 = " 33e = = = = = = = = # 1 # 1 # 1 # 1 = = = = = = = = supernovae : individual : sn 2002ap gamma - rays : bursts . .
And you have already written the first three sentences of the full article: supernova ( sn ) 2002ap in m74 was discovered by y. hirose and confirmed by r. kushida and w. li in images obtained on january 29 and 30 , 2002 ( nakano et al .
2002 ; ut dates are used throughout this _ letter _ ) .
the relative proximity of this event ( @xmath4 km s@xmath5 , @xmath6 mpc , tully 1988 ) and its ensuing brightness made it a promising target for intensive follow - up studies ..
Please generate the next two sentences of the article | three independent teams promptly obtained low resolution spectroscopic observations on jan .
30 ( meikle et al . 2002 ) , and jan . 31 ( kinugasa et al . 2002 , gal - yam & shemmer 2002 ) . |
9,327 | Suppose that you have an abstract for a scientific paper: in this work , we consider a _
generalized _ fault model that can be used to represent a wide range of failure scenarios , including correlated failures and non - uniform node reliabilities .
this fault model is general in the sense that fault models studied in prior related work , such as @xmath0-total and @xmath0-local models , are special cases of the generalized fault model . under the generalized fault model ,
we explore iterative approximate byzantine consensus ( iabc ) algorithms in arbitrary directed networks .
we prove a necessary and sufficient condition for the existence of iabc algorithms .
the use of the generalized fault model helps to gain a better understanding of iabc algorithms . .
And you have already written the first three sentences of the full article: dolev et al . @xcite introduced the notion of _ approximate byzantine consensus _ by relaxing the requirement of _ exact _ consensus @xcite . the goal in approximate consensus is to allow the fault - free nodes to agree on values that are approximately equal to each other ( and not necessarily exactly identical ) . in presence of byzantine faults , while _ exact _ consensus is impossible in _ asynchronous _
systems @xcite , approximate consensus is achievable @xcite .
the notion of approximate consensus is of interest in _ synchronous _ systems as well , since approximate consensus can be achieved using distributed algorithms that do not require complete knowledge of the network topology @xcite ..
Please generate the next two sentences of the article | the rest of the discussion in this paper assumes a _ synchronous _ systems .
the fault model assumed in much of the work on byzantine consensus allows up to @xmath0 byzantine faulty nodes in the network . |
9,328 | Suppose that you have an abstract for a scientific paper: in this paper , we use chebyshev polynomials to give presentations of the character varieties of certain types of 2-bridge knots .
this gives us an elementary method using basic calculations to discuss the number of irreducible components of the character varieties and thus to recover the results of burde on the irreducibility of non - abelian @xmath0-representation spaces in @xcite .
these results can be applied to determine some minimal elements of a partial ordering of prime knots . .
And you have already written the first three sentences of the full article: in 1980 culler and shalen introduced in @xcite an algebraic set in a complex space for a finitely presented group @xmath1 , now known as the character variety of @xmath1 . the framework of character varieties has been giving powerful tools and is now playing important roles in geometry and topology . on the other hand , it is not easy to calculate character varieties and thus to investigate the geometric structures in general , though an underlying idea of character varieties is simple as follows .
let @xmath1 be a finitely presented group generated by @xmath2 elements @xmath3 .
for a representation @xmath4 , the character @xmath5 of @xmath6 is the function on @xmath1 defined by @xmath7 ( @xmath8 ) . throughout this paper , we simply denote by @xmath9 the trace @xmath10 for an unspecified representation @xmath4 ..
Please generate the next two sentences of the article | we sometimes omit the brackets in the trace like @xmath11 for simplicity . by @xcite ( see also @xcite ) , _ the @xmath12-trace identity _
@xmath13 shows that @xmath9 is expressed by a polynomial in @xmath14 , @xmath15 and @xmath16 , for any @xmath17 . |
9,329 | Suppose that you have an abstract for a scientific paper: * abstract * we present results of transport measurements showing distinct path dependence of the electrical resistance in the superconducting vortex state of single crystal samples of ceru@xmath0 and v@xmath1si . resistance measured in the vortex state of both the systems prepared by field cooling ( fc ) , indicates a relatively higher degree of disorder than when it is prepared by isothermal variation of field .
small oscillations of magnetic field modify the resistance in the fc state , highlighting the metastable nature of that state .
an analogy is drawn with the fc state of the random - field ising systems . .
And you have already written the first three sentences of the full article: non - equilibrium properties associated with the peak - effect ( pe ) in the c15-laves phase superconductor ceru@xmath0 have drawn some attention in recent years @xcite . it is observed that in certain field ( h ) temperature ( t ) regime ( which includes part of the pe regime ) , the field - cooled ( fc ) vortex state in ceru@xmath0 is more disordered than the vortex state obtained by isothermal variation of h after zero field cooling ( zfc ) .
this fc vortex state in ceru@xmath0 is quite metastable in nature and susceptible to external fluctuations @xcite .
the origin of pe and the associated non - equilibrium properties in ceru@xmath0 remain a matter of debate and various possibilities , starting from a underlying phase transition@xcite to dynamical crossover in flux - pinning properties @xcite , have been put forward . in a recent communication @xcite.
Please generate the next two sentences of the article | we have drawn analogy between the zfc / fc response of the vortex state in and around the pe regime of ceru@xmath0 and the zfc / fc response of a random field ising systems ( rfim ) . through dc magnetization study in polycrystalline samples of ceru@xmath0
, we had shown that the magnetization hysteresis in the fc state is distinctly more than the zfc state . |
9,330 | Suppose that you have an abstract for a scientific paper: we consider a group of agents on a graph who repeatedly play the prisoner s dilemma game against their neighbors .
the players adapt their actions to the past behavior of their opponents by applying the win - stay lose - shift strategy . on a finite connected graph , it is easy to see that the system learns to cooperate by converging to the all - cooperate state in a finite time .
we analyze the rate of convergence in terms of the size and structure of the graph .
[ dyer et al . , 2002 ] showed that the system converges rapidly on the cycle , but that it takes a time exponential in the size of the graph to converge to cooperation on the complete graph .
we show that the emergence of cooperation is exponentially slow in some expander graphs .
more surprisingly , we show that it is also exponentially slow in bounded - degree trees , where many other dynamics are known to converge rapidly .
* keywords : * games on graphs , learning , prisoner s dilemma game , win - stay lose - shift , oriented percolation , emergence of cooperation . .
And you have already written the first three sentences of the full article: we consider a group of agents arranged on the nodes of a graph who repeatedly play the prisoner s dilemma game against their immediate neighbors .
the players adapt their actions to the past behavior of their opponents by applying the so - called win - stay lose - shift strategy @xcite which , as the name suggests , consists in changing strategy whenever the payoff is deemed unsatisfactory .
this model has been studied in the artificial intelligence literature @xcite as a simple example of `` co - learning '' @xcite . on a finite connected graph.
Please generate the next two sentences of the article | , it turns out that the system converges to the all - cooperate state the globally optimal state in finite time . in this respect , this instance of the iterated prisoner s dilemma ( ipd ) game on a graph provides an interesting example of a system learning to behave optimally by a mechanism that involves each agent applying independently a simple strategy or rule of thumb which takes into account only the latest actions of its immediate neighbors . for related work , see @xcite and references therein .
see also @xcite for the evolutionary perspective . in order to understand how persistent this `` emergence of cooperation '' |
9,331 | Suppose that you have an abstract for a scientific paper: recent results from the hermes experiment at hera are described .
the large data set from run - i has yielded new information on the helicity structure of the nucleon .
the data to be taken in run - ii will deal mainly with the transverse spin structure and with exclusive reactions . .
And you have already written the first three sentences of the full article: the flavour structure of nucleons is described in terms of parton distribution functions ( pdf ) .
the unpolarized pdf @xmath0 gives essentially the probability to find a parton with momentum fraction @xmath1 in a nucleon .
the polarized pdf s describe the spin structure of the nucleon ..
Please generate the next two sentences of the article | in particular the longitudinal pdf @xmath2 gives the helicity distribution of partons in the nucleon .
unpolarized pdf s have been measured in great detail over a wide range in @xmath1 and @xmath3 . |
9,332 | Suppose that you have an abstract for a scientific paper: let @xmath0 be a computable ergodic shift - invariant measure over @xmath1 . providing a constructive proof of shannon - mcmillan - breiman theorem
, vyugin proved that if @xmath2 is martin - lf random w.r.t .
@xmath0 then the strong effective dimension @xmath3 of @xmath4 equals the entropy of @xmath0 .
whether its effective dimension @xmath5 also equals the entropy was left as an problem question . in this paper
we settle this problem , providing a positive answer . a key step in the proof
consists in extending recent results on birkhoff s ergodic theorem for martin - lf random sequences .
+ _ keywords : shannon - mcmillan - breiman theorem ; martin - lf random sequence ; effective hausdorff dimension ; compression rate ; entropy . .
And you have already written the first three sentences of the full article: the _ effective dimension _ and _ strong effective dimension _ of an infinite binary sequence @xmath4 are defined as @xmath6 where @xmath7 is the kolmogorov complexity of @xmath8 .
they can be characterized as effective versions of hausdorff and packing dimensions respectively , or by divergence of @xmath9-gales ( see @xcite for the original results and @xcite for a survey ) .
let @xmath10 $ ] be a computable real number and @xmath11 the bernoulli measure over cantor space given by @xmath12=p^{|w|_1}(1-p)^{|w|_0}$ ] ..
Please generate the next two sentences of the article | it is well - known that if an infinite binary sequence @xmath4 is martin - lf random w.r.t .
@xmath11 then @xmath13 , where @xmath14 is the entropy of @xmath11 defined by @xmath15 this result is not difficult to prove and reduces to the strong law of large numbers for martin - lf random sequences , as on the one hand is the prefix version of kolmogorov complexity ] @xmath16+o(1)\ ] ] for @xmath11-random sequences by levin - schnorr theorem , and on the other hand @xmath17=-\frac{|x{\ensuremath{{\mathbin\upharpoonright}\raise-.2ex\hbox{\scriptsize $ n$}}}|_1}{n}\log(p)-\frac{|x{\ensuremath{{\mathbin\upharpoonright}\raise-.2ex\hbox{\scriptsize $ n$}}}|_0}{n}\log(1-p)\ ] ] which converge to @xmath14 for @xmath11-random sequences , by the strong law of large numbers for martin - lf random sequences . |
9,333 | Suppose that you have an abstract for a scientific paper: the 3d uniformly frustrated xy model is simulated to search for a predicted `` vortex loop blowout '' transition within the vortex line liquid phase of a strongly type - ii superconductor in an applied magnetic field .
results are shown to strongly depend on the precise scheme used to trace out vortex line paths .
while we find evidence for a transverse vortex path percolation transition , no signal of this transition is found in the specific heat . .
And you have already written the first three sentences of the full article: in pure extreme type - ii superconductors , such as the high @xmath0 superconductors , the abrikosov vortex line lattice melts via a sharp first order phase transition@xcite into a vortex line liquid as the temperature is increased above a critical @xmath1 .
the properties of this vortex line liquid phase have been the subject of considerable investigation .
theoretical arguments@xcite and early simulations@xcite suggested that the vortex line liquid might retain superconducting phase coherence parallel to the applied magnetic field , within some temperature interval above @xmath1 ..
Please generate the next two sentences of the article | later , better converged simulations@xcite found that phase coherence is simultaneously lost in all directions upon melting .
subsequently , teanovi@xcite has proposed that , for small magnetic fields , there still remains a sharp thermodynamic phase transition at a temperature @xmath2 within the vortex liquid state , associated with diverging fluctuations of closed vortex loops , such as drive the superconducting transition in the zero magnetic field case . |
9,334 | Suppose that you have an abstract for a scientific paper: we investigate the resonant production of the lighter sbottom at the proposed large hadron electron collider and its subsequent decay into @xmath0 final state , under the single coupling dominance hypothesis in the framework of the @xmath1-parity - violating minimal supersymmetric standard model .
it is concluded that the lhec running at the high electron beam energy configuration of @xmath2 would provide excellent opportunities to search for the sbottom resonance and probe the lepton - number - violating @xmath3 @xmath4-type yukawa interaction . with about @xmath5 integrated luminosity expected in @xmath2 @xmath6 collision at the lhec ,
either the lighter sbottom rpv resonance could be directly detected up to @xmath7 , or the @xmath8-violating coupling @xmath4 could be constrained at an unprecedented level of precision compared with all the knowledge derived from indirect measurements .
= 0.32 in addtoresetequationsection .
And you have already written the first three sentences of the full article: the standard model ( sm ) @xcite provides a remarkably successful description of strong , weak and electromagnetic interactions at the energy scale up to @xmath9 .
it implies the conservation of baryon number @xmath10 and lepton number @xmath8 as the automatic consequence of gauge invariance and renormalizability . despite its tremendous success ,
the sm suffers from some conceptional difficulties , such as the hierarchy problem and the nonoccurrence of gauge coupling unification at high energy scale ..
Please generate the next two sentences of the article | supersymmetry theories may provide solutions for such problems , and are widely expected as the most appealing extensions of the sm .
the simplest supersymmetric extension of the sm with minimal particle content is called minimal supersymmetric standard model ( mssm ) @xcite . to prevent proton from rapid decay @xcite , |
9,335 | Suppose that you have an abstract for a scientific paper: effective lagrangian for yang - mills gauge fields invariant under the standard space - time and local gauge @xmath0 transformations is considered .
it is demonstrated that a set of twelve degenerated minima exists as soon as a nonzero gluon condensate is postulated .
the minima are connected to each other by the parity transformations and weyl group transformations associated with the color @xmath1 algebra .
the presence of degenerated discrete minima in the effective potential leads to the solutions of the effective euclidean equations of motion in the form of the kink - like gauge field configurations interpolating between different minima .
spectrum of charged scalar field in the kink background is discussed .
+ pacs numbers : 12.38.aw , 12.38.lg , 14.70.dj * weyl group , cp and the kink - like field configurations in the effective @xmath0 gauge theory * b.v .
galilo @xmath2 , s.n .
nedelko @xmath3 + + .
And you have already written the first three sentences of the full article: the purpose of the paper is to expose potentially interesting relation of the weyl group associated with the color gauge @xmath0 symmetry to the structure of qcd vacuum . at the level of classical yang - mills
lagrangian the weyl group symmetry is trivial .
however , the vacuum structure of qcd is determined by quantum effects . the standard way to discuss the vacuum structure of.
Please generate the next two sentences of the article | the theory in terms of effective quantum action relates to the landau - ginsburg type construction based on the symmetries of the theory .
we consider the landau - ginsburg lagrangian for pure yang - mills gauge fields invariant under the standard space - time and local gauge @xmath0 transformations . |
9,336 | Suppose that you have an abstract for a scientific paper: we discuss recent calculations of electromagnetic form factors and strong decay widths of nucleon and delta resonances .
the calculations are done in a collective constituent model of the nucleon , in which the baryons are interpreted as rotations and vibrations of an oblate top . .
And you have already written the first three sentences of the full article: the study of the properties of baryon resonances is entering a new era with the forthcoming new and more accurate data from new facilities , such as jefferson lab .
, mami , elsa and brookhaven .
effective models of baryons which are based on three constituents ( @xmath0 ) share a common spin - flavor - color structure but differ in their assumptions on the spatial dynamics . for example , quark potential models in nonrelativistic @xcite or relativized @xcite forms emphasize the single - particle aspects of quark dynamics for which only a few low - lying configurations in the confining potential contribute significantly to the eigenstates of the hamiltonian . on the other hand , some regularities in the observed spectra , such as linear regge trajectories and parity doubling , hint that an alternative , collective type of dynamics may play a role in the structure of baryons . in this contribution.
Please generate the next two sentences of the article | we discuss a collective model within the context of an algebraic approach @xcite and present some results for electromagnetic form factors @xcite and strong decay widths @xcite .
1.75 in we consider a collective model in which the baryon resonances are interpreted in terms of rotations and vibrations of the string configuration in fig . |
9,337 | Suppose that you have an abstract for a scientific paper: the conversion @xmath0 of a neutrino with a magnetic moment is considered , caused by the additional wolfenstein energy acquired by a left - handed neutrino in medium , with an accurate taking account of the photon @xmath1 dispersion in medium .
it is shown that the threshold arises in the process , caused by the photon ( plasmon ) effective mass .
this threshold leaves no room for the so - called `` neutrino spin light '' in the most of astrophysical situations .
+ pacs nos . : 13.15.+g , 95.30.cq _ submitted to modern physics letters a _
the most important event in neutrino physics of the last decades was the solving of the solar neutrino problem , made in the unique experiment on the heavy - water detector at the sudbury neutrino observatory @xcite .
this experiment , together with the atmospheric and the reactor neutrino experiments @xcite , has confirmed the key idea by b. pontecorvo on neutrino oscillations @xcite . the existence of non - zero neutrino mass and lepton mixing is thereby established .
the sun appeared in this case as a natural laboratory for investigations of neutrino properties .
there exists a number of natural laboratories , the supernova explosions , where gigantic neutrino fluxes define in fact the process energetics .
it means that microscopic neutrino characteristics , such as the neutrino magnetic moment , the neutrino dispersion in an active medium , etc . , would have a critical impact on macroscopic properties of these astrophysical events .
this is the reason for a growing interest to neutrino physics in an external active medium . in an astrophysical environment
, the main medium influence on neutrino properties is defined by the additional wolfenstein energy @xmath2 acquired by a left - handed neutrino @xcite .
the general expression for this additional energy of a left - handed neutrino with the flavor @xmath3 is @xcite @xmath4 , \label{eq : enulgen}\end{aligned}\ ] ] where the functions @xmath5 are the number densities of....
And you have already written the first three sentences of the full article: the work was supported in part by the russian foundation for basic research under the grant no .
04 - 02 - 16253 , and by the council on grants by the president of russian federation for the support of young russian scientists and leading scientific schools of russian federation under the grant no .
nsh-6376.2006.2 ..
Please generate the next two sentences of the article | 99 q. r. ahmad _ et al . _
( sno collab . ) , _ phys . |
9,338 | Suppose that you have an abstract for a scientific paper: blazars , radio - loud active galactic nuclei with the relativistic jet closely aligned with the line of sight , dominate the extragalactic sky observed at gamma - ray energies , above 100 mev .
we discuss some of the emission properties of these sources , focusing in particular on the `` blazar sequence '' and the interpretative models of the high energy emission of bl lac objects . .
And you have already written the first three sentences of the full article: the extragalactic gamma - ray sky at energies above 100 mev is mainly populated by blazars , radio loud active galactic nuclei ( agns ) whose emission is dominated by the relativistically boosted non - thermal continuum produced in a relativistic jet ( bulk lorentz factor @xmath0 ) pointing ( typical angles less than 5 degrees ) toward the earth .
blazars are among the most powerful and violently variable sources in the universe : their emission covers all the electromagnetic spectrum , from the radio to the gamma - ray band , and their bolometric output ( often concentrated in the gamma - ray band ) can exceeds @xmath1 erg s@xmath2 . the variability timescale can be as short as few minutes@xcite@xcite .
the interest for these sources is driven by the possibility to probe the innermost regions and the surroundings of the relativistic jets , close to the acceleration and collimation region ( @xmath3 gravitational radii ) . in the past decade.
Please generate the next two sentences of the article | egret onboard _
cgro _ detected almost 70 blazars . |
9,339 | Suppose that you have an abstract for a scientific paper: we present optical identification and high - resolution spectroscopy of rosat sources in the field of the old open cluster m 67 . for the first time it is possible to analyze coronal and chromospheric activity of active stars in a solar - age cluster , and to compare it with field stars .
rosat observed the high x - ray luminosity tail of the cluster sources . in agreement with what expected from studies of field stars ,
most of the detected x - ray sources are binaries , preferably with short periods and eccentric orbits .
in addition , several of the m 67 rosat sources have peculiar locations in the cluster colour - magnitude diagram .
this is most likely due to rather complex evolutionary histories , involving the presence of mass transfer or large mass losses .
the x - ray luminosity of the sources does not scale with the stellar parameters in an obvious way .
in particular , no relationship is found between coronal emission and stellar magnitude or binary period .
the ca ii k chromospheric flux from most of the counterparts is in excess to that of single stars in the cluster by one order of magnitude .
the x - ray luminosity of the sources in the old m 67 is one order of magnitude lower than the most active active binaries in the field , but comparable to that of the much younger binaries in the hyades . .
And you have already written the first three sentences of the full article: the study of chromospheric and coronal activity has progressed impressively in the last two decades , thanks to the launch of x - ray satellites .
coronal sources have been detected in x rays all over the cool part of the h - r diagram ( vaiana et al .
1980 ) and active binaries of the rs cvn type have soon been recognized as powerful x - ray emitters ( walter et al ..
Please generate the next two sentences of the article | 1980 ) . with the advent of the rosat satellite and its all - sky survey ,
a complete x - ray study of known active binaries has been possible ( dempsey et al . |
9,340 | Suppose that you have an abstract for a scientific paper: the ( light but not - so - light ) strange quark may play a special role in the low - energy dynamics of qcd .
the presence of strange quark pairs in the sea may have a significant impact of the pattern of chiral symmetry breaking : in particular large differences can occur between the chiral limits of two and three massless flavours ( i.e. , whether @xmath0 is kept at its physical value or sent to zero ) .
this may induce problems of convergence in three - flavour chiral expansions . to cope with such difficulties , we introduce a new framework , called resummed chiral perturbation theory .
we exploit it to analyse @xmath1 and @xmath2 scatterings and match them with dispersive results in a frequentist framework .
constraints on three - flavour chiral order parameters are derived . .
And you have already written the first three sentences of the full article: because of its intermediate mass , the strange quark has a special status in low - energy qcd . it is light enough to allow for a combined expansion of observables in powers of @xmath3 around the @xmath4 chiral limit ( meaning 3 massless flavours ) : @xmath5 .
but it is sufficiently heavy to induce significant changes from the @xmath4 limit to the @xmath6 limit : @xmath7 and @xmath0 physical .
each limit can engender its own version of chiral perturbation theory ( @xmath8pt ) . in the @xmath6 limit ,.
Please generate the next two sentences of the article | the pions are the only degrees of freedom , whereas @xmath4 @xmath8pt deals with pions , kaons and @xmath9 .
this second version of @xmath8pt is richer , discusses more processes in a larger range of energy , but contains more unknown low - energy constants ( lecs ) and may have a slower convergence . |
9,341 | Suppose that you have an abstract for a scientific paper: several authors @xcite have implied that the original inspiration for parrondo s games was a physical system called a `` flashing brownian ratchet @xcite '' the relationship seems to be intuitively clear but , surprisingly , has not yet been established with rigor .
the dynamics of a flashing brownian ratchet can be described using a partial differential equation called the fokker - planck equation @xcite , that describes the probability density , of finding a particle at a certain place and time , under the influence of diffusion and externally applied fields . in this paper
, we apply standard finite - difference methods of numerical analysis @xcite to the fokker - planck equation .
we derive a set of finite difference equations and show that they have the same form as parrondo s games .
this justifies the claim that parrondo s games are a discrete - time , discrete - space version of a flashing brownian ratchet .
parrondo s games , are in effect , a particular way of sampling a fokker - planck equation .
our difference equations are a natural and physically motivated generalisation of parrondo s games .
we refer to some well established theorems of numerical analysis to suggest conditions under which the solutions to the difference equations and partial differential equations would converge .
the diffusion operator , implicitly assumed in parrondo s original games , reduces to the schmidt formula for the integration of the diffusion equation .
there is actually an infinite continuum of possible diffusion operators .
the schmidt formula is at one extreme of the feasible range .
we suggest that an operator in the middle of the feasible range , with half - period binomial weightings , would be a better representation of the underlying physics .
physical brownian ratchets have been constructed and have worked @xcite .
it is hoped that the finite element method presented here will be useful in the simulation and design of flashing brownian ratchets . .
And you have already written the first three sentences of the full article: one of the classical problems of statistical physics , and physical chemistry , is to find a macroscopic statistical description for the diffusion of a dissolved molecule or ion in a uniform fluid solvent .
the microscopic state of such a system has very many degrees of freedom , possibly even more than an avogadro number of degrees of freedom .
this gives rise to an equally large number of coupled equations of motion ..
Please generate the next two sentences of the article | it is completely impractical to solve such a large system with rigor .
we must abandon the idea of an exact solution . |
9,342 | Suppose that you have an abstract for a scientific paper: as discussed in @xcite , the extra stiffness that the magnetic field adds to the ism changes the way it reacts to the presence of a spiral perturbation . at intermediate to high @xmath0 , the gas shoots up before the arm , flows over , and falls behind it , as it approaches the next arm .
this generates a multicell circulation pattern , within each of which the net radial mass flux is positive near the midplane and negative at higher @xmath0 .
the flow distorts the magnetic field lines . in the arm region ,
the gas flows nearly parallel to the arm , and therefore , the magnetic field adopts a similar pitch angle . between the arms , the gas flows out in radius , generating a negative pitch angle in the magnetic field . the intensity and direction of the field yield synthetic synchrotron maps that reproduce some features of the synchrotron maps of external galaxies , like the islands of emission and the displacement between the gaseous and synchrotron arms . when comparing the magnitude of the field with the local gas density , two distinctive relations appear , depending on whether the magnetic pressure is dominant .
above the plane , the density structure develops a shape resembling a breaking wave .
this structure collapses and rises again with a period of about @xmath1 , similar to that of a vertical oscillation mode .
the falling gas plays an important part in the overall hydrostatics , since its deceleration compresses the low @xmath0 gas , raising the average midplane pressure in the interarm region above that provided by the weight of the material above . .
And you have already written the first three sentences of the full article: spiral structure is an astounding characteristic of disk galaxies . yet
, the nature of the spiral structure of our home galaxy is far from well understood .
the generally accepted model , originally discussed by @xcite , @xcite and @xcite , involves a density wave resulting from a global gravitational mode , triggered either by a internal instability or some driving element ( like a bar or an interacting external galaxy ) ..
Please generate the next two sentences of the article | another proposed model describes the spiral structure as a self - propagating wave of enhanced star formation @xcite . in either case , the models show the importance of the gaseous disk in the global spiral structure phenomenon . the role of the gas in the spiral structure has been exploited repeatedly in order to trace the spiral arms , both in the milky way and in external galaxies .
those efforts have included @xcite , co clouds @xcite and dust @xcite as tracers . |
9,343 | Suppose that you have an abstract for a scientific paper: the fluorescence detector of the pierre auger observatory measures the atmospheric depth , @xmath0 , where the longitudinal profile of the high energy air showers reaches its maximum .
this is sensitive to the nuclear mass composition of the cosmic rays .
due to its hybrid design , the pierre auger observatory also provides independent experimental observables obtained from the surface detector for the study of the nuclear mass composition .
we present @xmath0-distributions and an update of the average and rms values in different energy bins and compare them to the predictions for different nuclear masses of the primary particles and hadronic interaction models .
we also present the results of the composition - sensitive parameters derived from the ground level component . .
And you have already written the first three sentences of the full article: the determination of the nuclear mass composition of uhecr ( ultra high energy cosmic rays ) is fundamental to unveil the origin of the most energetic particles known in nature .
uhecr are detected by means of the extensive air showers created in the earth s atmosphere , which are composed by a cascade of hadrons and electromagnetic ( em ) particles .
the depth at which the em shower reaches its maximum , @xmath0 , strongly correlates with the depth where the primary firstly interacted ..
Please generate the next two sentences of the article | the @xmath0-distribution carries information about the primary particle and the physical processes in the cascade .
the hadronic cascade is composed mostly by pions , of which the charged pions might decay in flight into a muon and a neutrino . due to their long lifetime and low cross section , muons can leave the core of the hadronic cascade traveling kilometers away and be detected . |
9,344 | Suppose that you have an abstract for a scientific paper: the physics that can be learnt by studying exclusive channels in two photon interactions is recalled .
this serves as an introduction to the exclusive reaction session of photon99 . .
And you have already written the first three sentences of the full article: our main source of information about two photon interactions is the classic weizscker - williams process @xmath0 , where for exclusive channels @xmath1 is typically two to six mesons or a baryon - antibaryon final state .
the bulk of the data is obtained without tagging .
then , thanks to the behaviour of the photon propagator , the photons are almost on - shell . by factoring off the known @xmath2 vertices , we learn about real @xmath3 reactions.
Please generate the next two sentences of the article | see for example [ 1 ] . with tagging one can , of course , also investigate important @xmath4 collisions .
i will not review these , but rather refer to the later talk of bernard pire [ 2 ] . |
9,345 | Suppose that you have an abstract for a scientific paper: we consider the caching of content in the mobile devices in a wireless network using maximum distance separable ( mds ) codes .
we focus on a small cell , served by a base station ( bs ) , where mobile devices arrive and depart according to a poisson birth - death process .
users requesting a particular file download coded symbols from caching devices using device - to - device communication .
if additional symbols are required to decode the file , these are downloaded from the bs .
we optimize the mds codes to minimize the network load under a global average cache size constraint .
we show that , for most practical scenarios , using optimized mds codes results in significantly lower network load compared to when caching the most popular files .
furthermore , our results show that caching coded symbols of each file on all mobile devices , i.e. , maximal spreading , is optimal . .
And you have already written the first three sentences of the full article: mobile data traffic is predicted to grow by 800% in the next 6 years @xcite .
this imposes a severe strain on existing wireless networks .
one of the most promising methods to reduce downlink traffic is to store content closer to end users , commonly referred to as _ caching _ @xcite ..
Please generate the next two sentences of the article | caching has been studied extensively in recent years . in @xcite , a central server with access to a file library
serves a number of users , each with the ability to cache content , using a common channel . |
9,346 | Suppose that you have an abstract for a scientific paper: we report the final redshift release of the 6df galaxy survey , a combined redshift and peculiar velocity survey over the southern sky ( @xmath0 ) .
its 136304 spectra have yielded 110256 new extragalactic redshifts and a new catalogue of 125071 galaxies making near - complete samples with @xmath1 .
the median redshift of the survey is 0.053 .
survey data , including images , spectra , photometry and redshifts , are available through an online database .
we describe changes to the information in the database since earlier interim data releases .
future releases will include velocity dispersions , distances and peculiar velocities for the brightest early - type galaxies , comprising about 10% of the sample .
here we provide redshift maps of the southern local universe with @xmath2 , showing nearby large - scale structures in hitherto unseen detail .
a number of regions known previously to have a paucity of galaxies are confirmed as significantly underdense regions .
the url of the 6dfgs database is http://www-wfau.roe.ac.uk/6dfgs
. surveys galaxies : clustering galaxies : distances and redshifts cosmology : observations cosmology : large scale structure of universe .
And you have already written the first three sentences of the full article: .comparison of recent wide - area low - redshift galaxy surveys [ tab : othersurveys ] [ cols="<,^,^,^",options="header " , ] @xmath3 objects removed from the initial target list ( due to changes in + the 2mass source catalogue after 6dfgs was underway ) .
+ i d @xmath4 or 9999 in these cases . +
* columns : * + ( 1 ) i d : programme i d ( progid in the database ; see sec . [.
Please generate the next two sentences of the article | sec : release ] ) .
+ ( 2 ) survey sample : first sample ( in order of progid ) in which + object is found . |
9,347 | Suppose that you have an abstract for a scientific paper: the groverian entanglement measure introduced earlier for pure quantum states [ o. biham , m.a .
nielsen and t. osborne , phys .
rev .
a 65 , 062312 ( 2002 ) ] is generalized to the case of mixed states , in a way that maintains its operational interpretation .
the groverian measure of a mixed state of @xmath0 qubits is obtained by a purification procedure into a pure state of @xmath1 qubits , followed by an optimization process before the resulting state is fed into grover s search algorithm .
the groverian measure , expressed in terms of the maximal success probability of the algorithm , provides an operational measure of entanglement of both pure and mixed quantum states of multiple qubits .
these results may provide further insight into the role of entanglement in making quantum algorithms powerful . .
And you have already written the first three sentences of the full article: the potential speedup offered by quantum computers is exemplified by shor s factoring algorithm @xcite , grover s search algorithm @xcite , and algorithms for quantum simulation @xcite .
although the origin of this speed - up is not fully understood , there are indications that quantum entanglement plays a crucial role in making quantum algorithms efficient @xcite .
in particular , it was shown that quantum algorithms that do not create entanglement can be simulated efficiently on a classical computer @xcite ..
Please generate the next two sentences of the article | it is therefore of interest to quantify the entanglement produced by quantum algorithms and examine its correlation with their efficiency .
this requires to develop entanglement measures for the quantum states of multiple qubits that appear in quantum algorithms . |
9,348 | Suppose that you have an abstract for a scientific paper: in order to investigate the fir properties of radio - active agn , we have considered three different fields where both radio and fir observations are the deepest to - date : goods - south , goods - north and the lockman hole . out of a total of 92 radio - selected agn , @xmath0 are found to have a counterpart in _ herschel _ maps .
the percentage is maximum in the goods - north ( @xmath1% ) and minimum ( @xmath2% ) in the lockman hole , where fir observations are shallower .
our study shows that in all cases fir emission is associated to star - forming activity within the host galaxy .
such an activity can even be extremely intense , with star - forming rates as high as @xmath3 m@xmath4yr@xmath5 .
agn activity does not inhibit star formation in the host galaxy , just as on - site star - formation does not seem to affect agn properties , at least those detected at radio wavelengths and for @xmath6 . given the very high rate of fir detections , we stress that this refers to the majority of the sample : most radio - active agn are associated with intense episodes of star - formation .
however , the two processes proceed independently within the same galaxy , at all redshifts but in the local universe , where powerful enough radio activity reaches the necessary strength to switch off the on - site star formation .
our data also show that for z @xmath7 the hosts of radio - selected star - forming galaxies and agn are indistinguishable from each other both in terms of mass and ir luminosity distributions .
the two populations only differentiate in the very local universe , whereby the few agn which are still fir - active are found in galaxies with much higher masses and luminosities .
galaxies : evolution - infrared : galaxies - galaxies : starburst - galaxies : active - radio continuum : galaxies - methods : observational .
And you have already written the first three sentences of the full article: radio sources constitute an unequally powerful tool to investigate the origin and evolution of our universe .
in fact , radio emission is not obscured or attenuated by dust or gas , so deep radio surveys offer a unique opportunity to detect and study sources up to the highest redshifts .
it is following this rationale that very ambitious programs like the planned square kilometer array ( ska , carilli et al . , 2004 ).
Please generate the next two sentences of the article | facility , a gigantic radio telescope with a total collective area of 1 square kilometer , or its precursors askap ( australian ska pathfinder , johnston s. et al .
2007 ) and meerkat ( jonas j.l . 2009 ) will soon see their first light . |
9,349 | Suppose that you have an abstract for a scientific paper: we present a simple way of coding and compressing the data on board the planck instruments ( hfi and lfi ) to address the problem of the on board data reduction .
this is a critical issue in the planck mission . the total information that can be downloaded to earth is severely limited by the telemetry allocation .
this limitation could reduce the amount of diagnostics sent on the stability of the radiometers and , as a consequence , curb the final sensitivity of the cmb anisotropy maps . our proposal to address this problem consists in taking differences of consecutive circles at a given sky pointing .
to a good approximation , these differences are independent of the external signal , and are dominated by thermal ( white ) instrumental noise . using simulations and analytical predictions
we show that high compression rates , @xmath0 , can be obtained with minor or zero loss of cmb sensitivity .
possible effects of digital distortion are also analized .
the proposed scheme allows for flexibility to optimize the relation with other critical aspects of the mission .
thus , this study constitutes an important step towards a more realistic modeling of the final sensitivity of the cmb temperature anisotropy maps .
# 1 # 1([#1 ] ) # 1 # 1 # 1 # 1 # 1 # 1 # 1 # 1 # 1to 0pt#1 .
And you have already written the first three sentences of the full article: the planck satellite is designed to measure temperature fluctuations in the cosmic microwave background ( cmb ) with a precision of @xmath1 , and angular resolution of about 5 arcminutes .
the payload consists of a 1.5 - 2.0 m gregorian telescope which feeds two instruments : the high frequency instrument ( hfi ) with 56 bolometer arrays operated at @xmath2 and frequencies of @xmath3ghz and the low frequency instrument ( lfi ) with 56 tuned radio receivers arrays operated at @xmath4 ( @xmath5 ) and frequencies of @xmath6 ghz ( see http://astro.estec.esa.nl/sa-general/projects/planck/ for more information ) .
data on board planck consist of @xmath7 differential temperature measurements , spanning a range of values we shall call @xmath8 . preliminary studies and telemetry allocation indicate the need for compressing these data by a ratio of @xmath9 . here.
Please generate the next two sentences of the article | we will consider under what conditions it might be possible to achieve such a large compression factor .
a discretized data set can be represented by a number of bits , @xmath10 , which for linear analogue - to - digital converters ( adc ) is typically given by the maximum range @xmath11 : @xmath12 . if we express the joint probability for a set of n measurements as @xmath13 , we have that the shannon entropy per component of the data set is : h - 1 _ i_1 , , i_n p_i_1 , , i_n _ 2(p_i_1 , , i_n ) . |
9,350 | Suppose that you have an abstract for a scientific paper: we demonstrate that the higgs mechanism in three - dimensional topological superconductors exhibits unique features with experimentally observable consequences .
the higgs model we discuss has two superconducting components and an axion - like magnetoelectric term with the phase difference of the superconducting order parameters playing the role of the axion field . due to this additional term , quantum electromagnetic and phase fluctuations
lead to a robust topologically non - trivial state that holds also in the presence of interactions . in this sense , we show that the renormalization flow of the topologically nontrivial phase can not be continuously deformed into a topologically non - trivial one .
one consequence of our analysis of quantum critical fluctuations , is the possibility of having a first - order phase transition in the bulk and a second - order phase transition on the surface .
we also explore another consequence of the axionic higgs electrodynamics , namely , the anomalous hall effect . in the low frequency london regime an anomalous hall effect is induced in the presence of an applied electric field parallel to the surface .
this anomalous hall current is induced by a lorentz - like force arising from the axion term , and it involves the relative superfluid velocity of the superconducting components .
the anomalous hall current has a negative sign , a situation reminiscent of , but quite distinct in physical origin from the anomalous hall effect observed in high-@xmath0 superconductors .
in contrast to the latter , the anomalous hall effect in topological superconductors is non - dissipative and occurs in the absence of vortices . .
And you have already written the first three sentences of the full article: topological solid states of matter @xcite have the property that their bulk states are gapped , while states at the boundaries are gapless and protected by some discrete quantum symmetry .
the topological aspect emerges when considering the transport properties of the boundary states , where the transport current happens to also be a topological current .
the most well established topological solid states of matter are topological insulators ( tis ) , which are gapped in the bulk and have helical ( or chiral ) gapless states at the boundaries which are protected by time - reversal symmetry ..
Please generate the next two sentences of the article | helical here means that the electronic spin is locked to momentum due to strong spin - orbit coupling .
thus , the boundary states have an helicity determined by the eigenvalues of @xmath1 at each boundary . |
9,351 | Suppose that you have an abstract for a scientific paper: i present the exact solution of a family of fragmented bose - hubbard models and represent the models as graphs in one - dimension , two - dimensions and three - dimensions with the condensates in the vertices .
the models are solved by the algebraic bethe ansatz method . .
And you have already written the first three sentences of the full article: the realization of bose - einstein condensates ( bec)@xcite , achieved by taking dilute alkali gases to ultra low temperatures @xcite is certainly among the most exciting recent experimental achievements in physics .
since then , investigations dedicated to the comprehension of new phenomena associated to this state of matter as well as its properties have flourished , either in the experimental or theoretical domains .
the fast increasing of the control and production of bose - einstein condensates ( becs ) in different geometries has permitted the study of these systems in different physical situations ..
Please generate the next two sentences of the article | the fragmentation of a bec to produce a josephson junction @xcite using becs opened the possibility to study the quantum tunnelling of the atoms across a barrier between the condensates @xcite .
using superposition of light in different direction is possible to create any arbitrary trapping configuration as for example a ring or a superconducting quantum interference devices ( squid ) with an atom bec @xcite . |
9,352 | Suppose that you have an abstract for a scientific paper: all - linear - optical scheme for fully featured quantum router is presented .
this device directs the signal photonic qubit according to the state of one control photonic qubit . in the introduction
we formulate the list of requirements imposed on a fully quantum router .
then we describe our proposal showing the exact principle of operation on a linear - optical scheme .
subsequently we provide generalization of the scheme in order to optimize the success probability by means of a tunable controlled - phase gate . at the end , we show how one can modify the device to route multiple signal qubits using the same control qubit . .
And you have already written the first three sentences of the full article: quantum communications represent very important part of a rapidly developing research area called quantum information processing @xcite .
communications networks are nowadays an indispensable technology allowing people to transmit information quickly over large distances . in classical communications networks
classical physics laws are used for their construction ..
Please generate the next two sentences of the article | the recent research in quantum physics and quantum information suggests that quantum laws of nature can provide significant improvement of capabilities of communications devices @xcite , while using similar resources and keeping similar network architecture @xcite .
not surprisingly , a significant amount of theoretical and experimental research has been dedicated to the concept of quantum communications networks @xcite . |
9,353 | Suppose that you have an abstract for a scientific paper: periodicity is one of the most fundamental structural characteristics of systems occurring in nature .
the properties of these systems depend strongly on the symmetry of the underlying periodic structure . in solid state materials
for example the static and transport properties as well as the magnetic and electronic characteristics are crucially influenced by the crystal symmetry . in this context
, hexagonal structures play an extremely important role and lead to novel physics like that of carbon nanotubes or graphene . here
we report on the first realization of ultracold atoms in a spin - dependent optical lattice with hexagonal symmetry .
we show how combined effects of the lattice and interactions between atoms lead to a forced antiferromagnetic nel order when two spin - components localize at different lattice sites .
we also demonstrate that the coexistence of two components one mott - insulating and the other one superfluid leads to the formation of a forced supersolid .
our observations are consistent with theoretical predictions using gutzwiller mean - field theory . in recent years
, ultracold atoms in periodic potentials@xcite have been widely recognized as an important tool to simulate solid state systems and study their transport@xcite and magnetic properties@xcite .
different types of spin- and/or state - dependent lattices have been implemented and studied@xcite .
so far , most experiments with ultracold quantum gases have been carried out in lattices of cubic symmetry .
however , recent theoretical developments@xcite are aiming at systems with a hexagonal geometry .
in particular , carbon nanotubes@xcite , graphene@xcite and a large number of other carbon - based compounds show fascinating effects and exhibit particularly rich quantum phases@xcite . in this paper
we discuss the first realization of ultracold quantum gases in a hexagonal , spin - dependent optical potential and demonstrate how it can be used to tailor quantum phases of spin - mixtures and their....
And you have already written the first three sentences of the full article: the basic structure of the spin - dependent hexagonal optical lattice discussed in this paper is illustrated in fig .
[ fig:1 ] .
three laser - beams intersecting under an angle of @xmath0 and with each beam linearly polarized in the plane of intersection lead to the formation of local potential minima in a hexagonal structure . for neighboring sites along the vertices of the hexagonal lattice as for example indicated in fig ..
Please generate the next two sentences of the article | [ fig:1]a by a dashed line , the local polarization alternates between @xmath1 and @xmath2 . as atoms in a light field experience a polarization - dependent ac stark shift , the potential at these @xmath1 and @xmath2 sites is different for different atomic zeeman substates labeled by @xmath3 .
the potential can be written as : @xmath4 where the polarization of the light field @xmath5 ( @xmath6 for pure @xmath1 and @xmath7 for pure @xmath2 polarizations ) is mapped onto a pseudo - magnetic field @xmath8 , @xmath9 the land @xmath10-factor and @xmath11 the bohr magneton ( for details see appendix ) . |
9,354 | Suppose that you have an abstract for a scientific paper: high - order spatial discretisations and full discretisations of parabolic partial differential equations on evolving surfaces are studied .
we prove convergence of the high - order evolving surface finite element method , by showing high - order versions of geometric approximation errors and perturbation error estimates and by the careful error analysis of a modified ritz map .
furthermore , convergence of full discretisations using backward difference formulae and implicit runge kutta methods are also shown .
parabolic problems , evolving surfaces , high - order esfem , ritz map , convergence , bdf and runge kutta methods msc : 35r01 , 65m60 , 65m15 , 65m12 .
And you have already written the first three sentences of the full article: numerical methods for partial differential equations ( pdes ) on stationary and evolving surfaces and for coupled bulk
surface pdes are under intensive research in the recent years .
surface finite element methods are all based on the fundamental paper of @xcite , further developed for evolving surface parabolic problems by @xcite ..
Please generate the next two sentences of the article | high - order versions of various finite element methods for problems on a _ stationary surface _ have received attention in a number of publications previously .
we give a brief overview on this literature here : * the surface finite element method of @xcite was extended to higher order finite elements on stationary surfaces by @xcite . |
9,355 | Suppose that you have an abstract for a scientific paper: we consider a state discrimination problem which deals with settings of minimum - error and unambiguous discrimination systematically by introducing a margin for the probability of an incorrect guess .
we analyze discrimination of three symmetric pure states of a qubit .
the measurements are classified into three types , and one of the three types is optimal depending on the value of the error margin . the problem is formulated as one of semidefinite programming . starting with the dual problem derived from the primal one , we analytically obtain the optimal success probability and the optimal measurement that attains it in each domain of the error margin .
moreover , we analyze the case of three symmetric mixed states of a qubit . .
And you have already written the first three sentences of the full article: in quantum mechanics , it is well known that there is no way to distinguish different nonorthogonal quantum states perfectly without a wrong guess by measurement .
this is because quantum measurement is statistical in nature and it generally destroys the state of the system to be measured .
quantum state discrimination @xcite , as with many ideas in quantum information theory , is most easily understood using the metaphor of a game involving two parties , alice and bob ..
Please generate the next two sentences of the article | alice chooses a state @xmath0 @xmath1 from a set of quantum states @xmath2 with some occurrence probabilities known to both parties .
she gives state @xmath0 to bob , whose task is to identify the given state @xmath0 with one in the set @xmath2 . |
9,356 | Suppose that you have an abstract for a scientific paper: we study some properties of the tachyonic lumps in the level truncation scheme of bosonic cubic string field theory .
we find that several gauges work well and that the size of the lump as well as its tension is approximately independent of these gauge choices at level ( 2,4 ) .
we also examine the fluctuation spectrum around the lump solution , and find that a tachyon with @xmath0 and some massive scalars appear on the lump world - volume .
this result strongly supports the conjecture that a codimension 1 lump solution is identified with a d - brane of one lower dimension within the framework of bosonic cubic string field theory .
ut-944 + hep - th/0106068 + june , 2001 1.5 cm * * 1.5 cm + + .
And you have already written the first three sentences of the full article: in the past years , the tachyonic lump solutions @xcite as well as the tachyon potential @xcite have been worked out in bosonic cubic string field theory @xcite using the level truncation scheme . however , these calculations were carried out only in the feynman - siegel gauge . although its validity has been checked in @xcite , it would be interesting to see whether other gauge choices are possible .
in fact , it has recently been found in @xcite that the feynman - siegel gauge condition has a finite range of validity , and that some other gauge choices lead to similar tachyon potentials to that in the feynman - siegel gauge .
it is the problem of choosing the gauge fixing condition(s ) that we will address in the first half of this paper ..
Please generate the next two sentences of the article | we will see that we can successfully construct lump solutions with nearly correct tensions in several gauges , and that the widths of the lumps are independent of these gauge chioces at least at level ( 2,4 ) .
concerning this point , in the recent studies of so - called ` vacuum string field theory'@xcite it was guessed that the width of the lump solution was a gauge - dependent quantity @xcite . in more detail , let us consider the center - of - mass coordinate @xmath1 of the string and its conjugate momentum @xmath2 , obeying the canonical commutation relation @xmath3=i\eta^{\mu\nu}. \label{eq : a}\ ] ] combining these two operators , we can move to the oscillator representation @xcite of the zero modes as @xcite @xmath4 it is easily found that they satisfy the commutation relation @xmath5= \eta^{\mu\nu}$ ] for the creation - annihilation operators irrespective of the value of the newly introduced parameter @xmath6 . |
9,357 | Suppose that you have an abstract for a scientific paper: we study the existence and stability of localized states in the discrete nonlinear schrdinger equation ( dnls ) on two - dimensional non - square lattices .
the model includes both the nearest - neighbor and long - range interactions . for the fundamental strongly localized soliton ,
the results depend on the coordination number , i.e. , on the particular type of the lattice .
the long - range interactions additionally destabilize the discrete soliton , or make it more stable , if the sign of the interaction is , respectively , the same as or opposite to the sign of the short - range interaction .
we also explore more complicated solutions , such as twisted localized modes ( tlm s ) and solutions carrying multiple topological charge ( vortices ) that are specific to the triangular and honeycomb lattices . in the cases when such vortices are unstable
, direct simulations demonstrate that they turn into zero - vorticity fundamental solitons . .
And you have already written the first three sentences of the full article: in the past decade , energy self - localization in nonlinear dynamical lattices , leading to the formation of soliton - like _ intrinsic localized modes _ ( ilms ) , has become a topic of intense theoretical and experimental research .
much of this work has already been summarized in several reviews @xcite .
it was proposed that this mechanism would be relevant to a number of effects such as nonexponential energy relaxation in solids @xcite , local denaturation of the dna double strand @xcite , behavior of amorphous materials @xcite , propagation of light beams in coupled optical waveguides @xcite or the self - trapping of vibrational energy in proteins @xcite , among others ..
Please generate the next two sentences of the article | ilms also have potential significance in some crystals , like acetanilide and related organics @xcite .
the theoretical efforts were complemented by a number of important experimental works suggesting the presence and importance of the ilms in magnetic @xcite and complex electronic materials @xcite , dna denaturation @xcite , as well as in coupled optical waveguide arrays @xcite and josephson ladders @xcite . |
9,358 | Suppose that you have an abstract for a scientific paper: we report experimental results for the influence of a tilt angle @xmath0 relative to gravity on turbulent rayleigh - bnard convection of cylindrical samples .
the measurements were made at rayleigh numbers @xmath1 up to @xmath2 with two samples of height @xmath3 equal to the diameter @xmath4 ( aspect ratio @xmath5 ) , one with @xmath6 m ( the large " sample ) and the other with @xmath7 m ( the medium " sample ) . the fluid was water with a prandtl number @xmath8 .
in contrast to the experiences reported by @xcite for a similar sample but with @xmath9 ( @xmath10 and @xmath11 m ) , we found no long relaxation times . for @xmath12 we measured the nusselt number @xmath13 as a function of @xmath0 and obtained a small @xmath0 dependence given by @xmath14 $ ] when @xmath0 is in radian .
this depression of @xmath15 is about a factor of 50 smaller than the result found by @xcite for their @xmath9 sample .
we measured side - wall temperatures at eight equally spaced azimuthal locations on the horizontal mid - plane of the sample and used them to obtain cross - correlation functions between opposite azimuthal locations .
the correlation functions had gaussian peaks centered about @xmath16 that corresponded to half a turn - over time of the large - scale circulation ( lsc ) and yielded reynolds numbers @xmath17 of the lsc . for the large sample and @xmath12 we found
@xmath18 $ ] .
similar results were obtained also from the auto - correlation functions of individual thermometers .
these results are consistent with measurements of the amplitude @xmath19 of the azimuthal side - wall temperature - variation at the mid - plane that gave @xmath20 $ ] for the same @xmath1 .
an important conclusion is that the increase of the speed ( i.e. of @xmath21 ) with @xmath0 of the lsc does not significantly influence the heat transport .
thus the heat transport must be determined primarily by the instability mechanism operative in the boundary layers , rather than by the rate at which plumes " are....
And you have already written the first three sentences of the full article: turbulent convection in a fluid heated from below , known as rayleigh - bnard convection ( rbc ) , has been under intense study for some time [ for reviews , see _
e.g. _ @xcite ] .
a central prediction of models for this system [ @xcite ] is the heat transported by the fluid ..
Please generate the next two sentences of the article | it is usually described in terms of the nusselt number @xmath25 where @xmath26 is the heat current , @xmath3 the cell height , @xmath27 the cross - sectional area , @xmath28 the thermal conductivity , and @xmath29 the applied temperature difference .
the nusselt number depends on the rayleigh number @xmath30 and on the prandtl number @xmath31 here @xmath32 is the isobaric thermal expansion coefficient , @xmath33 the acceleration of gravity , @xmath34 the thermal diffusivity , and @xmath35 the kinematic viscosity . |
9,359 | Suppose that you have an abstract for a scientific paper: we study how the properties of allowing multiple positive nondegenerate equilibria ( mpne ) and multiple positive linearly stable equilibria ( mpse ) are inherited in chemical reaction networks ( crns ) . specifically , when is it that we can deduce that a crn admits mpne or mpse based on analysis of its subnetworks ? using basic techniques from analysis we are able to identify a number of situations where mpne and mpse
are `` inherited '' as we build up a network .
some of these modifications are known while others are new , but all results are proved using the same basic framework , which we believe will yield further results .
the results are presented primarily for mass action kinetics , although with natural , and in some cases immediate , generalisation to other classes of kinetics .
multiple equilibria ; chemical reaction networks * msc . * 80a30 ; 15a15 ; 37c25 .
And you have already written the first three sentences of the full article: the idea of studying `` network motifs '' in biological systems , namely simple , frequently occurring , structures from which some properties of the system may be inferred , has attracted considerable recent interest ( for example @xcite ) . the reason is quite natural : systems biology proceeds dually by elucidating the functioning of subsystems while at the same time attempting to fit together these pieces to explain large - scale behaviours in biological systems . at the heart of this study is a need to know how behaviours in a dynamical system are affected by embedding this system in some larger system in well - defined ways .
some rigorous results in this area come from the literature on hyperbolicity and structural stability ( @xcite , for example ) , and on monotone control systems ( @xcite , for example ) .
a closely related type of question is when a behaviour known to occur in some member of a _ family _ of dynamical systems @xmath0 can be guaranteed to occur in some member of a new family @xmath1 related to @xmath0 in some natural sense ..
Please generate the next two sentences of the article | our goal here is understanding the inheritance of _ multiple positive nondegenerate equilibria _
( mpne , definition [ defmpne ] below ) and _ multiple positive linearly stable equilibria _ ( mpse , definition [ defmpse ] below ) in chemical reaction networks ( crns ) which form the main component of most biological models . |
9,360 | Suppose that you have an abstract for a scientific paper: we report the discovery of a small aggregate of young stars seen in high - resolution , deep near - infrared ( @xmath0 ) images towards iras 06345 - 3023 in the outer galaxy and well below the mid - plane of the galactic disc .
the group of young stars is likely to be composed of low - mass stars , mostly class i young stellar objects .
the stars are seen towards a molecular cloud whose co map peaks at the location of the iras source .
the near - infrared images reveal , additionally , the presence of nebular emission with rich morphological features , including arcs in the vicinity of embedded stars , wisps and bright rims of a butterfly - shaped dark cloud . the location of this molecular cloud as a new star formation site well below the galactic plane in the outer galaxy indicates that active star formation is taking place at vertical distances larger than those typical of the ( thin ) disc .
[ firstpage ] stars : formation infrared : stars ism : clouds ism : individual objects : iras 06345 - 3023 dust , extinction galaxy : stellar content . .
And you have already written the first three sentences of the full article: star formation occurs across the galactic disc with most molecular material concentrated at low latitudes @xmath1 .
both in the inner and in the outer galaxy , young stars still partly embedded in the dense gas and dust in molecular clouds have been found ( e.g. , * ? ? ?
* ; * ? ? ?.
Please generate the next two sentences of the article | * ; * ? ? ?
* ; * ? ? ? |
9,361 | Suppose that you have an abstract for a scientific paper: we theoretically propose quantum spin pumping mediated by magnons , under a time - dependent transverse magnetic field , at the interface between a ferromagnetic insulator and a non - magnetic metal .
the generation of a spin current under a thermal equilibrium condition is discussed by calculating the spin relaxation torque , which breaks the spin conservation law for conduction electrons and operates the coherent magnon state .
localized spins lose spin angular momentum by emitting magnons and conduction electrons flip from down to up by absorbing the momentum .
the spin relaxation torque has a resonance structure as a function of the angular frequency of the applied transverse field .
this fact is useful to enhance the spin pumping effect induced by quantum fluctuations .
we also discuss the distinction between our quantum spin pumping theory and the one proposed by tserkovnyak et al . .
And you have already written the first three sentences of the full article: a new branch of physics called spintronics has seen a rapid development over the last decades .
the central theme is the active manipulation of spin degrees of freedom as well as charge ones of electrons ; spintronics avoids the dissipation from joule heating by replacing charge currents with spin currents . thus establishing methods for the generation of a spin current
is significant from viewpoints of fundamental science and potential applications to green information and communication technologies.@xcite a standard way to generate a ( pure ) spin current is the spin pumping effect at the interface between a ferromagnetic material and a non - magnetic metal ..
Please generate the next two sentences of the article | there the precession of the magnetization induces a spin current pumped into a non - magnetic metal , which is proportional to the rate of precession of the magnetic moment .
the precessing ferromagnet acts as a source of spin angular momentum ; spin battery . |
9,362 | Suppose that you have an abstract for a scientific paper: we demonstrate that the spectrum rearrangement can be considered as a precursor and a basis for the metal - insulator transition observed in graphene dosed with hydrogen atoms .
the anderson - type transition is attributed to the fermi level s entering into the quasigap , which develop in the vicinity of the impurity resonance energy due to the anomalous spectrum rearrangement .
theoretical results for the lifshitz impurity model are in a reasonable agreement with available experimental data . .
And you have already written the first three sentences of the full article: since the existence of dirac quasiparticles has been proved for graphene , one of the most intriguing issues of its physics is the possibility of their localization by whichever imperfection that can appear in the honeycomb lattice.@xcite moreover , it should not be overlooked that the effect of disorder on the transport of quasiparticles is sensitive to the nature of inhomogeneity , be it caused by short - range or long - range defects , neutral or charged impurities , adsorbed or interstitial atoms or molecules , vacancies , spatial distortions or structural irregularities , including ripples on the graphene sheet and other long - wave random modulations .
all these different types of imperfections necessitate corresponding dedicated studies , which can not be accomplished by resorting to a single impurity model .
since these imperfections are rather dissimilar both in their character and action on basic properties of graphene , respective theoretical models should be diverse as well ..
Please generate the next two sentences of the article | early experiments on graphene - based devices , which were engineered like a commonplace field effect transistors , revealed that the sample conductivity never drops below a certain _ minimal _
value.@xcite this fact , indeed , considerably reduced audacious expectations that corresponding devices are capable to serve as next - generation electronic switches . |
9,363 | Suppose that you have an abstract for a scientific paper: we calculate the quantum correction to the classical conductance of a disordered mesoscopic normal - superconducting ( ns ) junction in which the electron spatial and spin degrees of freedom are coupled by an appreciable spin orbit interaction .
we use random matrix theory to describe the scattering in the normal part of the junction and consider both quasi - ballistic and diffusive junctions .
the dependence of the junction conductance on the schottky barrier transparency at the ns interface is also considered .
we find that the quantum correction is sensitive to the breaking of spin rotation symmetry even when the junction is in a magnetic field and time reversal symmetry is broken .
we demonstrate that this sensitivity is due to quantum interference between scattering processes which involve electrons and holes traversing closed loops in the same direction .
we explain why such processes are sensitive to the spin orbit interaction but not to a magnetic field .
finally we consider the effect of the spin orbit interaction on the phenomenon of `` reflectionless tunnelling . ''
short title : the so interaction in mesoscopic ns junctions . .
And you have already written the first three sentences of the full article: in mesoscopic samples of disordered normal metals at low temperatures it is possible to observe a quantum correction to the classical boltzmann conductance @xcite . here mesoscopic means that within the sample , the interaction of a single electron with other degrees of freedom , such as other electrons , phonons , magnetic impurities etc .
, can be neglected .
such a situation can be realised in semiconductor and metal nanostructures cooled to milli - kelvin temperatures ..
Please generate the next two sentences of the article | the origin of the quantum correction is quantum interference between time reversed scattering paths .
( by `` time reversed path '' |
9,364 | Suppose that you have an abstract for a scientific paper: lead perchlorate , part of the omnis supernova neutrino detector , contains two nuclei , @xmath0pb and @xmath1cl , that might be used to study nucleon decay .
both would produce signatures that will make them especially useful for studying less - well - studied neutron decay modes , _
e.g. _ , those in which only neutrinos are emitted . .
And you have already written the first three sentences of the full article: studies of nucleon decay ( see , _ e.g. _ , @xcite ) are among the most important in physics , in that they provide direct tests of fundamental theories of particle physics .
the different particle theories make rather different predictions as to what the nucleon decay half - lives might be , and even which decay modes would be expected to dominate .
although a number of searches for nucleon decay have been performed in the large detectors that exist , no convincing evidence has yet been presented for its existence ..
Please generate the next two sentences of the article | the best limits from these studies have involved decay modes in which protons decay to relativistic charged leptons ( see , _ e.g. _ , @xcite ) , either as individual protons or as protons in nuclei , as the resulting cherenkov radiation would produce definitive signatures , typically of order 10@xmath2 y. however , nucleon decays in composite nuclei @xcite might produce clear evidence for the existence of such effects that could not be obtained from decay of isolated protons .
furthermore , these might allow extension of the existing limits of the decay branches in some instances , even with relatively small detectors . |
9,365 | Suppose that you have an abstract for a scientific paper: we present the structural and magnetic properties of a new compound family , mg@xmath0re@xmath1sb@xmath1o@xmath2 ( re = gd , dy , er ) , with a hitherto unstudied frustrating lattice , the tripod kagome " structure .
susceptibility ( ac , dc ) and specific heat exhibit features that are understood within a simple luttinger - tisza type theory . for
re = gd , we found long ranged order ( lro ) at 1.65 k , which is consistent with a 120 @xmath3 structure , demonstrating the importance of diople interactions for this 2d heisenberg system . for re = dy , lro at 0.37 k is related to the
kagome spin ice ( ksi ) " physics for a 2d system .
this result shows that the tripod kagome structure accelerates the transition to lro predicted for the related pyrochlore systems . for re = er , two transitions , at 80 mk and 2.1 k are observed , suggesting the importance of quantum fluctuations for this putative xy system . _
introduction. _ the two - dimensional ( 2d ) kagome lattice magnet ( klm ) has been a favorite in the theoretical condensed matter community since the experimental work on scgo @xcite , due to the strong frustration associated with its network of corner - shared triangles .
many exotic states are predicted , such as the quantum spin liquid ( qsl ) state @xcite , the spin - orbital liquid state @xcite , the kagome spin ice ( ksi ) state @xcite , dipolar spin order @xcite , the kosterlitz - thouless ( kt ) phase transition @xcite , quantum order by disorder ( qobd ) @xcite , and nematicity and supernematicity @xcite .
the large variety of exotic states predicted for kagome spin systems lies in contrast to a paucity of experimental systems .
early efforts include the exploration of langasites re@xmath1ga@xmath4sio@xmath2@xcite , which possess a distorted kagome lattice .
recent attention has been paid to vesignieite bacu@xmath1v@xmath0o@xmath5(oh)@xmath0 @xcite and herbertsmithite zncu@xmath1(oh)@xmath6cl@xmath0 @xcite .
the later one shows intriguing signs of qsl behavior @xcite .....
And you have already written the first three sentences of the full article: polycrystalline samples of tripod kagome lattice ( tkl ) compounds mg@xmath0re@xmath1sb@xmath1o@xmath2 ( re = gd , dy , er ) were synthesized by solid state reactions .
stoichiometric ratios of re@xmath0o@xmath1 ( re = gd , dy , er ) , mgo , and sb@xmath0o@xmath1 powder were carefully ground and reacted at a temperature of 1573 k for 60 hours with several intermediate grindings .
performing the reaction at temperatures above 1623 k will introduce site - disorder between the re site and the mg site , which is evidenced by the cubic pyrochlore phase in x - ray diffraction ( xrd ) patterns ..
Please generate the next two sentences of the article | the room temperature xrd patterns were measured with a huber x - ray powder diffractometer with the structural refinements performed using software package _ fullprof - suite_. the dc susceptibility measurements were performed using a commercial superconducting interference device ( squid ) magnetometer with a magnetic field of 200 oe . the ac susceptibility was measured at national high magnetic field laboratory with the conventional mutual inductance technique at frequencies between 80 hz and 700 hz .
the low temperature specific heat measurements were performed in a he3-he4 dilution refrigerator using the semi - adiabatic heat pulse technique . |
9,366 | Suppose that you have an abstract for a scientific paper: the next generation of gravitational wave ( gw ) detectors is expected to fully enter into the quantum regime of force and displacement detection . with this aim , it is important to scale up the experiments on opto - mechanical effects from the microscopic regime to large mass systems and test the schemes that should be applied to reach the quantum regime of detection . in this work we present the experimental characterization of a prototype of massive gw detector , composed of two oscillators with a mass of the order of the kg ,
whose distance is read by a high finesse optical cavity .
the mechanical response function is measured by exciting the oscillators though modulated radiation pressure .
we demonstrate two effects crucial for the next generation of massive , cryogenic gw detectors ( dual detectors ) : a ) the reduction of the contribution of local susceptibility thanks to an average over a large interrogation area .
such effect is measured on the photo - thermal response thanks to the first implementation of a folded - fabry - perot cavity ; b ) the back - action reduction due to negative interference between acoustic modes . moreover
, we obtain the active cooling of an oscillation mode through radiation pressure , on the described mechanical device which is several orders of magnitude heavier than previously demonstrated radiation - pressure cooled systems . .
And you have already written the first three sentences of the full article: ground - based gravitational wave ( gw ) detectors are traditionally classified into large baseline interferometers and resonant antennas . recently
, a new class of gw detectors has been proposed , based on huge masses kept at cryogenic temperature and called dual detectors @xcite-@xcite . at difference from previous massive cryogenic antennas ( such as weber bars ) , the dual system do not aim at reaching the best peak sensitivity in a narrow band around a resonance frequency , but it takes advantage of elastic forces to achieve a useful sensitivity in a wide frequency range . for this purpose , it is no longer equipped with resonant mechanical amplifiers , and it needs a very sensitive readout . the goal is realizing a detector which covers the acoustic frequency region ( 1 - 5 khz ) .
a dual gw detector exploits two oscillation modes of a mechanical system with a readout symmetric with respect to the center of mass ..
Please generate the next two sentences of the article | do to the geometry , the responses to the readout force of the two modes must be summed , while the responses to the tidal force of the gw are subtracted . in the frequency region between the two resonance frequencies , the susceptibilities of the two modes
are in anti - phase , giving a reduced response to the readout force and an enhanced response to the gw @xcite ( back - action reduction ) . |
9,367 | Suppose that you have an abstract for a scientific paper: the effect of cooling on a number of observables is calculated in su(2 ) lattice gauge theory .
the static quark - antiquark potential and spin - dependent interactions are studied , and the topological charge is monitored .
the chiral symmetry breaking order parameter @xmath0 and meson correlators are calculated using staggered fermions .
interactions on the distance scale of a few lattice spacings are found to be essentially eliminated by cooling , including the spin - dependent potentials .
@xmath0 and meson correlators up to time separations of several lattice spacings relax very quickly to their free - field values . at larger times
, there is evidence of a difference between the pseudoscalar and vector channels .
a fit to the pseudoscalar correlation function yields `` mass '' values about @xmath1 ( in lattice units ) of the uncooled masses .
these results raise the question of how to reconcile the large - time behavior of the hadron correlators with the fact that the spin - dependent potentials and @xmath0 essentially disappear ( in lattice units ) after only a small amount of cooling . .
And you have already written the first three sentences of the full article: cooling in lattice field theory is a technique for exposing the topological features of field configurations @xcite .
recently , using this method , evidence has been presented @xcite that instantons play a dominant role in determining hadron properties in quantum chromodynamics ( qcd ) .
this conclusion was based on the calculation of long - distance properties of a variety of hadronic correlation functions ..
Please generate the next two sentences of the article | it has been argued , however , that the persistence of long - distance effects ( particularly , confinement @xcite ) is an inevitable consequence of the local nature of the cooling procedure and is not indicative of the underlying dynamics @xcite . to gain some more insight into what cooling is doing
we have extended our work @xcite on three - dimensional qed to four - dimensional qcd with su(2 ) color . |
9,368 | Suppose that you have an abstract for a scientific paper: abstract in the framework of loop quantum gravity ( lqg ) , having quantum black holes in mind , we generalize the previous boundary state counting ( gr - qc/0508085 ) to a full bulk state counting . after a suitable gauge fixing
we are able to compute the bulk entropy of a bounded region ( the black hole " ) with fixed boundary .
this allows us to study the relationship between the entropy and the boundary area in details and we identify the holographic regime of lqg where the leading order of the entropy scales with the area .
we show that in this regime we can fine tune the factor between entropy and area without changing the immirzi parameter . .
And you have already written the first three sentences of the full article: to understand the deep structure of loop quantum gravity ( lqg ) @xcite , in particular the holographic principle and quantum black holes , it is necessary to analyze in detail the entropy counting .
most of the work on black hole entropy in lqg focuses on boundary state counting , especially in the isolated horizon framework @xcite . in the present work we propose to extend these considerations to the bulk entropy .
we use the framework outlined in @xcite . we consider a given spin network state for the 3d geometry of the ( canonical ).
Please generate the next two sentences of the article | hypersurface and focus on an arbitrary bounded region . the previous work @xcite analyzed the boundary entropy of such a region assuming a totally mixed state , i.e having no knowledge about its interior .
we naturally recovered the area - entropy law . in the present work , |
9,369 | Suppose that you have an abstract for a scientific paper: transverse - field muon - spin rotation ( @xmath0sr ) experiments were performed on a single crystal sample of the non - centrosymmetric system mnsi .
the observed angular dependence of the muon precession frequencies matches perfectly the one of the mn - dipolar fields acting on the muons stopping at a 4@xmath1 position of the crystallographic structure .
the data provide a precise determination of the magnetic dipolar tensor .
in addition , we have calculated the shape of the field distribution expected below the magnetic transition temperature @xmath2 at the 4@xmath1 muon - site when no external magnetic field is applied .
we show that this field distribution is consistent with the one reported by zero - field @xmath0sr studies .
finally , we present _ ab initio _ calculations based on the density - functional theory which confirm the position of the muon stopping site inferred from transverse - field @xmath0sr . in view of the presented evidence
we conclude that the @xmath0sr response of mnsi can be perfectly and fully understood without invoking a hypothetical magnetic polaron state . .
And you have already written the first three sentences of the full article: in recent years a growing interest has been focused on crystalline systems lacking inversion symmetry ( see for example ref . ) . a direct consequence of non - centrosymmetry is the occurrence of a spin - orbit dzyaloshinsky - moriya ( dm ) interaction @xcite .
the dm interaction is thought to play an important role in multiferroic systems and may be at play in the occurrence of non - trivial magnetic structures . on the other hand , non - centrosymmetric systems presenting superconductivity have attracted special attention as the absence of parity symmetry considerably restricts the possible superconducting states ( i.e. a pure triplet pairing is in principle not allowed without inversion symmetry ) @xcite .
mnsi is probably the non - centrosymmetric system which concentrates most of the research focus ..
Please generate the next two sentences of the article | it was the first material found to exhibit a homochiral spin spiral structure below @xmath3 k @xcite .
this spin spiral adopts a very long wavelength of about 18 nm . |
9,370 | Suppose that you have an abstract for a scientific paper: we have studied in detail the spectrum of the decay @xmath0 as a function of the electron helicity , and verify the prediction @xcite that a significant fraction of the electrons in this decay is right - handed .
these `` wrong - helicity '' electrons persist in the limit @xmath1 , and are connected with helicity - flip bremsstrahlung in qed .
the longitudinal polarization of the electron is calculated as a function of the photon and electron energy , and deviates systematically from the naive v - a prediction @xmath2 .
the right - handed component is concentrated in the collinear region @xmath3 . in the limit @xmath4
, we reproduce the results obtained in @xcite using the helicity - flip splitting function introduced by falk and sehgal . .
And you have already written the first three sentences of the full article: in a recent letter @xcite it was pointed out that as a consequence of helicity - flip bremsstrahlung , electrons in the radiative decay @xmath0 are not purely left - handed , even in the limit @xmath5 . the decay width into right - handed electrons was shown to be @xmath6 , where @xmath7 .
the energy spectrum of these wrong - helicity electrons was calculated , as also that of the photons accompanying them .
these results were obtained using the helicity - flip splitting function @xmath8 introduced by falk and sehgal @xcite ..
Please generate the next two sentences of the article | the appearance of right - handed electrons in @xmath9-decay is , at first sight , surprising since it goes against the conventional wisdom based on the v - a structure of weak interaction and the common assumption of helicity - conservation in massless qed
. however persistence of helicity - flip bremsstrahlung in the @xmath5 limit has been established in several calculations of radiative processes @xcite , going back to the seminal paper of lee and nauenberg @xcite . in all cases , |
9,371 | Suppose that you have an abstract for a scientific paper: we present an algorithm for the optimization of a class of finite element integration loop nests .
this algorithm , which exploits fundamental mathematical properties of finite element operators , is proven to achieve a locally optimal operation count . in specified circumstances
the optimum achieved is global .
extensive numerical experiments demonstrate significant performance improvements over the state of the art in finite element code generation in almost all cases .
this validates the effectiveness of the algorithm presented here , and illustrates its limitations .
this work was supported by by the department of computing at imperial college london , the engineering and physical sciences research council [ grant number ep / l000407/1 ] , and the natural environment research council [ grant numbers ne / k008951/1 and ne / k006789/1 ] , and by a hipeac collaboration grant .
the authors would like to thank dr .
andrew t.t .
mcrae , dr . lawrence mitchell , and dr .
francis russell for their invaluable suggestions and their contribution to the firedrake project .
author s addresses : fabio luporini @xmath0 paul h. j. kelly , department of computing , imperial college london ; david a. ham , department of mathematics , imperial college london ; .
And you have already written the first three sentences of the full article: the need for rapid implementation of high performance , robust , and portable finite element methods has led to approaches based on automated code generation .
this has been proven successful in the context of the fenics @xcite and firedrake @xcite projects . in these frameworks ,
the weak variational form of a problem is expressed in a high level mathematical syntax by means of the domain - specific language ufl @xcite ..
Please generate the next two sentences of the article | this mathematical specification is used by a domain - specific compiler , known as a form compiler , to generate low - level c or c++ code for the integration over a single element of the computational mesh of the variational problem s left and right hand side operators .
the code for assembly operators must be carefully optimized : as the complexity of a variational form increases , in terms of number of derivatives , pre - multiplying functions , or polynomial order of the chosen function spaces , the operation count increases , with the result that assembly often accounts for a significant fraction of the overall runtime . as demonstrated by the substantial body of research on the topic , automating the generation of such high performance implementations poses several challenges . |
9,372 | Suppose that you have an abstract for a scientific paper: the effect of thermally annealing a slab of wurtzite zno , terminated by two surfaces , ( 0 0 0 1 ) ( which is oxygen - terminated ) and ( 0 0 0 @xmath0 ) ( which is zn - terminated ) , is investigated via molecular dynamics simulation using reactive force field ( reaxff ) .
we found that upon heating at or beyond a threshold temperature 700 k @xmath1 k , surface oxygen atoms begin to sublimate from the ( 0 0 0 1 ) surface , meanwhile no atom leaves the ( 0 0 0 @xmath0 ) surface . the ratio of oxygen leaving the surface at a given temperature @xmath2 increases as @xmath2 increases ( for @xmath3 ) .
a photoluminescence ( pl ) measurement has been carried out to assess the effect of annealing wurtzite zno surfaces .
the relative luminescence intensity of the secondary peak in the pl data , interpreted as a measurement of amount of vacancies on the sample surfaces , qualitatively agrees with the threshold behavior as found in the md simulations .
our simulations have also revealed the formation of oxygen dimers on the surface and evolution of partial charge distribution in the slab during the annealing process .
we have also simulated the annealing on the ( 1 0 0 0 ) and ( @xmath0 0 0 0 ) surfaces but found no robust sign of sublimation .
the thermal behavior of a zno slab revealed by our md simulation based on the reaxff is consistent with experimental observations .
molecular dynamics , reactive force field , annealing , zno surface .
And you have already written the first three sentences of the full article: zno has been extensively studied , both theoretically and experimentally , due to its many promising applications in piezoelectric devices , transistors , photodiodes , photocatalysis and antibacterial function @xcite .
the physical properties of zno , especially its surface properties , can be experimentally modified at the atomic level for the purpose of , e.g. , engineering the material for desired functionality . since zno contacts with its external environment through its surfaces , monitoring
how the surface properties respond to external perturbation ( e.g. thermal treatment ) can provide valuable insights to improve our ability to manipulate zno for application purposes ..
Please generate the next two sentences of the article | one of the simplest way to experimentally modify the surfaces of zno is by heating it to elevated temperature ( but not exceeding its melting point ) .
heating zno can be easily carried out in practice , and many works had been reported along this line @xcite . |
9,373 | Suppose that you have an abstract for a scientific paper: we report the magnetotransport properties of ferromagnet ( fm)/antiferromagnet ( afm ) fe@xmath0crsi
/ ru@xmath0mnge epitaxial bilayers using current - in - plane configurations . above the critical thickness of the ru@xmath0mnge layer to induce exchange bias , symmetric and asymmetric curves
were observed in response to the direction of fm magnetocrystalline anisotropy . because each magnetoresistance curve showed full and partial afm rotation ,
the magnetoresistance curves imply the impact of the fe@xmath0crsi magnetocrystalline anisotropy to govern the afm rotation . the maximum magnitude of the angular - dependent resistance - change ratio of the bilayers is more than an order of magnitude larger than that of single - layer fe@xmath0crsi films , resulting from the reorientation of afm spins via the fm rotation .
these results highlight the essential role of controlling the afm rotation and reveal a facile approach to detect the afm moment even in current - in - plane configurations in fm / afm bilayers . .
And you have already written the first three sentences of the full article: antiferromagnets ( afms ) show great potential to replace ferromagnets ( fms ) in spintronic applications @xcite . compared with fms , afms
have the advantages of much faster spin dynamics @xcite , more stability against charge and external field perturbations @xcite , and no stray field @xcite .
however , since the afm spins align in alternating directions of magnetic moments on individual atoms , the resulting zero net magnetization makes hard to control afm magnetic moments ..
Please generate the next two sentences of the article | recently , there have been several reports regarding the control of afm moments by applying an electronic current in afm films @xcite and fm / afm bilayers @xcite , by field cooling ( fc ) @xcite and by applying an external field via the exchange - spring effect @xcite .
these studies demonstrated that the afm moments can be controlled and detected using electronic transport measurements without the need for large - scale facilities such as synchrotron and neutron facilities @xcite . |
9,374 | Suppose that you have an abstract for a scientific paper: using a global equation of state , empirically derived by luding , we accurately model the density profile of a two - dimensional hard sphere system with diameter @xmath0 and mass @xmath1 under gravity with a given temperature @xmath2 [ physica a , 271 , 192 ( 1999 ) ] .
we then compare our solutions to md simulated data . from the density profile
, we can then solve for the critical temperature @xmath3 , which we define as the temperature at which the system begins to condensate .
then , if @xmath2 is below @xmath3 , there is some frozen portion of the system .
we derive a formula for the number of frozen layers @xmath4 , and compare our solution to the number of frozen layers in our simulated data .
pacs number(s ) 64.70.dv , 05.20.dd , 51.10.+y .
And you have already written the first three sentences of the full article: because of the large number of relatively small particles that compose a granular system , granular media tends to act like a collection of microscopic molecules .
however , individual grains in a granular system have a macroscopic mass .
thus , particle collisions and gravity play a much larger role than in molecular systems , making it impossible to fully explain their mechanics in terms of kinetic theory alone . understanding hard sphere ( hs ) systems.
Please generate the next two sentences of the article | is crucial for analyzing important physical phenomena in our world , such as avalanches , earthquakes , and powder production .
newer models that correct for characteristics such as higher densities and dissipation in granular materials have succeeded in explaining simulated and experimental results that were previously left unsolved . in a paper by hong , [ 1 ] , a method for modeling a granular system was developed by observing the effect of lowering the excitation level of a highly excited system of grains . |
9,375 | Suppose that you have an abstract for a scientific paper: the problem of finding a microscopic theory of phase transitions across a critical point is a central unsolved problem in theoretical physics . we find a general solution to that problem and present it here for the cases of bose - einstein condensation in an interacting gas and ferromagnetism in a lattice of spins , interacting via a heisenberg or ising hamiltonian . for bose - einstein condensation ,
we present the exact , valid for the entire critical region , equations for the green s functions and order parameter , that is a critical - region extension of the beliaev - popov and gross - pitaevskii equations . for the magnetic phase transition
, we find an exact theory in terms of constrained bosons in a lattice and obtain similar equations for the green s functions and order parameter . in particular , we outline an exact solution for the three - dimensional ising model
. published in physica scripta * 90 * , 108002 ( 2015 ) , doi:10.1088/0031 - 8949/90/10/108002 .
keywords : critical phenomena , mesoscopic system , phase transitions , spontaneous symmetry breaking , microscopic theory , bose - einstein condensation , ferromagnetism . .
And you have already written the first three sentences of the full article: the problem is to find a microscopic theory of the second order phase transitions that would allow one to follow a formation of an ordered phase from a disordered phase across an entire critical region continuously .
the microscopic theory should be derived for a given microscopic hamiltonian of a mesoscopic or macroscopic system from the first principles of statistical physics and describe an order parameter , correlations as well as other statistical and thermodynamic quantities . since landau s breakthrough paper of 1937 @xcite
, it is known that the phase transitions , leading to ferromagnetism , bose - einstein condensation ( bec ) , superfluidity , superconductivity , liquid crystal phases , ferroelectricity and so on , originate from restructuring of a many - body system due to spontaneous symmetry breaking ..
Please generate the next two sentences of the article | landau gave a general mean - field theory of spontaneous symmetry breaking .
however , an exact solution for a particular ising model of a magnetic phase transition in a 2-dimensional ( 2d ) lattice of spins , found by onsager @xcite in 1944 and presented in detail by yang @xcite in 1952 , showed that the landau theory was incorrect in the most interesting region surrounding a critical point of a phase transition . according to the ginzburg - levanyuk criterion @xcite , found in 1960 , in the critical region of a system s parameters , the fluctuations of the order parameter are anomalously large , that is they exceed the mean value of the order parameter . |
9,376 | Suppose that you have an abstract for a scientific paper: we present here the 7.0 8.7 @xmath0 m spectrum of the bright reflection nebula ngc 7023 .
our observations are made with the short wavelength spectrometer ( sws ) on the european satellite infrared space observatory ( iso ) .
the vibrational bands of the ionized fullerene c@xmath1 are expected at 7.11 and 7.51 @xmath0 m , while those of the neutral fullerene c@xmath2 are expected at 7.0 and 8.45 @xmath0 m .
we estimate an upper limit in ngc 7023 for the c@xmath1 abundance of @xmath30.26% of the interstellar abundance of carbon , while c@xmath2 contains @xmath30.27% of interstellar carbon . .
And you have already written the first three sentences of the full article: kroto et al . ( 1985 ) proposed that the fullerene molecule c@xmath2 and related species play an important role in interstellar physics and chemistry .
this argument is based on the stability of the `` buckyball '' structure of fullerene compounds , as observed in the laboratory and confirmed by ab - initio calculations ( see also kroto 1987 , 1988 and references therein ) .
the formation mechanisms invoked to produce such spherical carbonaceous structures are usually based on reactions in circumstellar shells , with precursors such as acetylene and corannulene ( goeres and seldmayr 1992 ; kroto and jura 1992 ; bettens et al ..
Please generate the next two sentences of the article | another way of obtaining fullerenes , together with polycyclic aromatic hydrocarbons ( pahs ) , is the photoerosion of larger hydrogenated amorphous carbon grains ( scott et al . 1997 ) .
fullerene or fullerane species have been searched for at various wavelengths in interstellar spectra . |
9,377 | Suppose that you have an abstract for a scientific paper: we discuss a class of binary parametric families with conditional probabilities taking the form of generalized linear models and show that this approach allows to model high - dimensional random binary vectors with arbitrary mean and correlation .
we derive the special case of logistic conditionals as an approximation to the ising - type exponential distribution and provide empirical evidence that this parametric family indeed outperforms competing approaches in terms of feasible correlations . .
And you have already written the first three sentences of the full article: the need to sample random vectors of correlated binary variables arises in various statistical application ; examples are estimation of the posterior mean in bayesian variable selection @xcite , small - sample properties of estimators in longitudinal studies ( * ? ? ?
* for a recent review ) , stochastic binary optimization in combinatorics @xcite , simulation of ferromagnetic materials @xcite , performance of neural networks @xcite and market segmentation analysis @xcite among others .
let @xmath0 denote the binary space . in some cases , such as small - sample analysis in longitudinal studies ,.
Please generate the next two sentences of the article | we need a parametric family @xmath1 explicitly for sampling data on @xmath2 with specified mean and correlations .
in other cases , the parametric family serves as a proxy for a more complex distribution we can not directly sample from . |
9,378 | Suppose that you have an abstract for a scientific paper: in measuring the power spectrum of the distribution of large numbers of dark matter particles in simulations , or galaxies in observations , one has to use fast fourier transforms ( fft ) for calculational efficiency .
however , because of the required mass assignment onto grid points in this method , the measured power spectrum @xmath0 obtained with an fft is not the true power spectrum @xmath1 but instead one that is convolved with a window function @xmath2 in fourier space . in a recent paper , jing ( 2005 ) proposed an elegant algorithm to deconvolve the sampling effects of the window function and to extract the true power spectrum , and tests using n - body simulations show that this algorithm works very well for the three most commonly used mass assignment functions , i.e. , the nearest grid point ( ngp ) , the cloud in cell ( cic ) and the triangular shaped cloud ( tsc ) methods . in this paper , rather than trying to deconvolve the sampling effects of the window function , we propose to select a particular function in performing the mass assignment that can minimize these effects .
an ideal window function should fulfill the following criteria : ( i ) compact top - hat like support in fourier space to minimize the sampling effects ; ( ii ) compact support in real space to allow a fast and computationally feasible mass assignment onto grids .
we find that the scale functions of daubechies wavelet transformations are good candidates for such a purpose .
our tests using data from the millennium simulation show that the true power spectrum of dark matter can be accurately measured at a level better than 2% up to @xmath3 , without applying any deconvolution processes .
the new scheme is especially valuable for measurements of higher order statistics , e.g. the bi - spectrum , where it can render the mass assignment effects negligible up to comparatively high @xmath4 . .
And you have already written the first three sentences of the full article: in studies of the cosmic large - scale structure , a number of different statistical methods are routinely used to extract various information of interest ( e.g. , regarding the cosmology , the initial perturbation , etc ) that is embedded in the distribution of the dark matter particles ( in the case of simulations ) or the galaxies ( in observations ) .
the power spectrum @xmath1 is one of the most powerful and basic statistical measures that describes the distribution of mass and light in the universe , and one of the most throughly investigated quantities in modelling the structure formation process .
the initial primordial power spectrum of the mass fluctuations is usually assumed to follow a power law , @xmath5 ..
Please generate the next two sentences of the article | the linearly processed power spectrum @xmath6 can be well predicted by codes such as cmbfast ( seljak & zaldarriaga 1996 ) , or approximated by various fitting formula ( e.g. bardeen et al .
1986 ; efstathiou , bond & white 1992 ; eisenstein & hu 1998 ) for different matter and energy content . |
9,379 | Suppose that you have an abstract for a scientific paper: we find that a theoretical fit to all the hd 209458b data at secondary eclipse requires that the dayside atmosphere of hd 209458b have a thermal inversion and a stratosphere .
this inversion is caused by the capture of optical stellar flux by an absorber of uncertain origin that resides at altitude .
one consequence of stratospheric heating and temperature inversion is the flipping of water absorption features into _ emission _ features from the near- to the mid - infrared and we see evidence of such a water emission feature in the recent hd 209458b irac data of knutson et al .
in addition , an upper - atmosphere optical absorber may help explain both the weaker - than - expected na d feature seen in transit and the fact that the transit radius at 24 @xmath0 m is smaller than the corresponding radius in the optical .
moreover , it may be a factor in why hd 209458b s optical transit radius is as large as it is .
we speculate on the nature of this absorber and the planets whose atmospheres may , or may not , be affected by its presence . .
And you have already written the first three sentences of the full article: of the more than 235 extrasolar giant planets ( egps " ) discovered in the last twelve years , 22 are transiting their primaries .
the most thoroughly studied transiting egp is hd 209458b ( henry et al . 2000 ; charbonneau et al .
2000 ; brown et al . 2001.
Please generate the next two sentences of the article | ; melo et al . 2006 ; santos , israelian , & mayor 2004 ; knutson et al .
2007a ) . for transiting egps , not only |
9,380 | Suppose that you have an abstract for a scientific paper: quantum theoretical treatment of coherent forward scattering of light in a polarized atomic ensemble with an arbitrary angular momentum is developed .
we consider coherent forward scattering of a weak radiation field interacting with a realistic multi - level atomic transition .
based on the concept of an effective hamiltonian and on the heisenberg formalism , we discuss the coupled dynamics of the quantum fluctuations of the polarization stokes components of propagating light and of the collective spin fluctuations of the scattering atoms . we show that in the process of coherent forward scattering this dynamics can be described in terms of a polariton - type spin wave created in the atomic sample .
our work presents a general example of entangling process in the system of collective quantum states of light and atomic angular momenta , previously considered only for the case of spin @xmath0 atoms .
we use the developed general formalism to test the applicability of spin @xmath0 approximation for modelling the quantum non - demolishing measurement of atoms with a higher angular momentum . .
And you have already written the first three sentences of the full article: various optical phenomena associated with the optical pumping process , which have been comprehensively studied since the 60 s and described in many aspects in a famous review @xcite by w.happer , is revived nowadays in a new form within the field of quantum information and quantum computing .
the paramagnetic ground states of macroscopic atomic spin subsystems are considered now convenient physical objects for mapping and storing the quantum information in the quantum states of their collective angular momenta .
the faraday - type interference scheme was proposed for spin squeezing @xcite and for quantum communication between atomic ensembles @xcite ..
Please generate the next two sentences of the article | the proposed ideas were realized in spin squeezing @xcite and in the entanglement @xcite experiments , where a quantum measurement on the light forward - scattered from atomic ensembles was used .
the same kind of off - resonant forward scattering combined with a quantum feedback was used in the recent demonstration of quantum memory for light @xcite . |
9,381 | Suppose that you have an abstract for a scientific paper: the authors in their previous papers obtained compact , arbitrarily accurate expressions for two - center one- and two - electron relativistic molecular integrals expressed over slater - type orbitals . in this present study ,
the accuracy limits of given expressions is examined for three - center nuclear attraction integrals , which are the first integral set do not have analytically closed form relations .
they are expressed through new molecular auxiliary functions obtained via neumann expansion of coulomb interaction .
the numerical global adaptive method is used to evaluate these integrals for arbitrarily values of orbital parameters , quantum numbers .
several methods , such as laplace expansion of coulomb interaction , single - center expansion , fourier transformation method , have been performed in order to evaluate these integrals considering the values of principal quantum numbers in the set of positive integer numbers .
this is the first attempts to study the three - center integrals without any restrictions on quantum numbers and in all ranges of orbital parameters .
keywords : : pacs numbers : : ... . .
And you have already written the first three sentences of the full article: the lcao - scf @xcite method is generally employed for molecules , in which molecular wave functions taken to be linear combinations of atomic basis functions whose should possess the cusps condition at the nuclei @xcite and decay exponentially for large distances @xcite .
this approach leads to use , namely , slater - type orbitals @xcite , @xmath0 here , @xmath1 are complex or real spherical harmonics @xmath2 differs from the condon@xmath3shortley phases by sign factor @xmath4 @xcite , @xmath5 are gamma functions @xcite , @xmath6 are the principal , orbital , magnetic quantum numbers with , @xmath7 , @xmath8 , @xmath9 and @xmath10 stands for the integer part of @xmath11 , respectively , in one@xmath3 and two@xmath3electron multi@xmath3center molecular integrals . these integrals needs to be calculated in spectroscopic accuracy in order to meaningful discussions on basis - set expansion methods , born - oppenheimer energy , vibrational frequency calculations . the difficulty of finding analytically closed form relations , however , for molecular integrals have more than two - center referred to as _ the bottleneck of quantum chemistry _
@xcite , have been greatest obstacle since slater - type orbitals have no simple addition theorem ; relations for products of two slater - type orbitals centered on different positions not available in compact form @xcite ..
Please generate the next two sentences of the article | the slater - type orbitals are obtained by simplification of laguerre functions in hydrogen@xmath3like orbitals @xcite by keeping only the term of the highest power of @xmath12 , for integer values of principal quantum number @xmath11 ( istos ) , where @xmath13 , @xmath14 and it has been proved that they provide extra flexibility for closer variational description of atoms and molecules by considering the values of @xmath11 in more general set of number , namely positive real numbers ( nstos ) , where @xmath7 .
the studies on the evaluation of molecular integrals , thus , are performed in two main group : those restrict the principal quantum number with integer values , which are practically used in nonrelativistic molecular electronic structure calculations @xcite and those free them from any specification but also reduce the area of applications only to investigation of atoms @xcite . |
9,382 | Suppose that you have an abstract for a scientific paper: the nonrelativistic full - folding optical model approach for nucleon - nucleus scattering is extended into the relativistic regime . in doing so
, kinematical issues involving the off - shell lorentz boost of the colliding particles between the two nucleons and the projectile - nucleus center - of - mass reference frames have been taken into account .
the two - body effective interaction is obtained in the framework of the nuclear matter @xmath0-matrix using nucleon - nucleon optical model potentials that fully account for the inelasticities and isobar resonances in the continuum at nucleon energies up to 3 gev .
diverse nucleon - nucleon potential models were constructed by supplementing the basic paris , nijmegen , argonne or gelfand - levitan - marchenko inversion potentials with complex separable terms . in each case
the additional separable terms ensured that the combination led to nn scattering phase shifts in excellent agreement with experimental values . with each phase shift
fitting potential nuclear matter @xmath0-matrices have been formed and with each of those relativistic full - folding optical potentials for nucleon - nucleus elastic scattering determined .
application to such scattering for projectile energies to 1.5 gev have been made .
good and systematic agreement is obtained between the calculated and measured observables , both differential and integrated quantities , over the whole energy range of our study . a moderate sensitivity to off - shell effects in the differential scattering observables also is observed . .
And you have already written the first three sentences of the full article: elastic nucleon - nucleus ( na ) scattering is known now as an excellent means of testing nuclear structure @xcite .
results of the nonrelativistic theory for such scattering confidently can be used as predictive for information required in applied nuclear technology , where large amounts of nuclear reaction data including fission cross sections at intermediate energies are required for various challenging applications such as accelerator transmutation of waste , particularly the elimination of long - lived radioactive wastes with a spallation source , accelerator - based conversion to destroy weapon grade plutonium , accelerator - driven energy production to derive fission energy from thorium with concurrent destruction of the long - lived waste and without the production of nuclear weapon material , and accelerator production of tritium @xcite .
there is also a great need for such information to be the base in analyzes of patient radiation therapy and protection . with basic science.
Please generate the next two sentences of the article | there is the intellectual challenge to go beyond the physics of a single hadron and understand essential aspects of nuclear physics from first principles such as qcd @xcite .
it is generally agreed that the qcd lagrangian involves nonlinear dynamics . |
9,383 | Suppose that you have an abstract for a scientific paper: experimental studies of spin transport in a two - dimensional electron gas hosted by a triple gaas / algaas quantum well are reported . using time - resolved kerr rotation , we observed the precession of the spin polarization about a current - controlled spin - orbit magnetic field .
spatially - resolved imaging showed a large variation of the electron @xmath0-factor and the drift transport of coherent electron spins over distances exceeding half - millimetre in a direction transverse to the electric field . .
And you have already written the first three sentences of the full article: for the successful implementation of new functionalities using the spin degree of freedom in technological platforms , experimental techniques are required for the generation of spin polarization , transport across relevant length scales and polarization detection . for device applications of non - equilibrium electron spins , triggered by either optical @xcite or electrical techniques @xcite , the generation and detection of spin currents
should be accomplished without the use of extremely strong magnetic fields and desirably using only electrical voltages . the electrical generation of spin polarization
have been widely studied in semiconductor structures of different dimensionality such as bulk samples @xcite and in n- and p - doped quantum wells ( qws ) @xcite ..
Please generate the next two sentences of the article | the transport of spins polarized by an electrical current is of great interest not only due to the emergence of new phenomena but also due to possible applications in spin based electronics @xcite
. transverse transport of in - plane current - induced spin polarization ( cisp ) have been studied in l - shaped strained n - ingaas channels @xcite . |
9,384 | Suppose that you have an abstract for a scientific paper: we present an example revealing that the sign of the `` momentum '' @xmath0 of the wigner `` distribution '' function @xmath1 is not necessarily associated with the direction of motion in the real world .
this aspect , which is not related to the well known limitation of the wigner function that traces back to the heisenberg s uncertainty principle , is particularly relevant in transport studies , wherein it is helpful to distinguish between electrons flowing from electrodes into devices and vice versa .
recently , we critically analyzed @xcite the manner in which the wigner `` distribution '' function was used in studies on molecular transport relying upon finite isolated clusters @xcite .
these studies made us aware of a limitation of using the wigner function as a true momentum distribution function for transport , which we could not find in the literature and want to present here .
the wigner function @xmath1 is employed in many physical studies , including transport s , in spite of its physical limitations .
the limitation known from textbooks @xcite traces back to the heisenberg s uncertainty principle
. the wigner `` distribution '' function can be negative and should be not interpreted as a probability distribution , but rather as `` one step in the calculation never the last step , since '' is not measurable but `` is used to calculate other quantities that can be measured the particle density and current '' and ``
no problems are encountered as long as one avoids interpreting @xmath2 as a probability density '' ( quotations from ch .
3.7 , p. 203 of ref . ) . in transport , it is helpful to distinguish between incoming and outgoing electrons , i. e. , flowing from electrodes into devices and from devices into electrodes @xcite . to this aim
, it is necessary to use a physical property whose sign enables to indubitably assess that electrons are , say , left- or right - moving .
the averages of the particle ( probability ) current operator @xmath3 , \ ] ] or of the....
And you have already written the first three sentences of the full article: the financial support provided by the deutsche forschungsgemeinschaft is gratefully acknowledged ..
Please generate the next two sentences of the article | |
9,385 | Suppose that you have an abstract for a scientific paper: the instantaneous transition rate of an arbitrarily accelerated unruh - dewitt particle detector on four - dimensional minkowski space is ill defined without regularisation .
we show that schlicht s regularisation as the zero - size limit of a lorentz - function spatial profile yields a manifestly well - defined transition rate with physically reasonable asymptotic properties . in the special case of stationary trajectories , including uniform acceleration
, we recover the results that have been previously obtained by a regularisation that relies on the stationarity .
finally , we discuss evidence for the conjecture that the zero - size limit of the transition rate is independent of the detector profile . .
And you have already written the first three sentences of the full article: starting with the seminal work of unruh @xcite , it has now been recognised for 30 years that a uniformly accelerated observer in minkowski space sees minkowski vacuum as a thermal state in temperature @xmath0 , where @xmath1 is the magnitude of the proper acceleration .
this result is of interest already in its own right within flat spacetime quantum field theory , and it has been confirmed by a number of methods @xcite . for relativists ,
the result is of particular interest because of its close mathematical similarity to the thermal properties of quantum fields in stationary black hole spacetimes @xcite ..
Please generate the next two sentences of the article | a conceptually concrete way to address quantum effects in accelerated motion is to analyse a particle detector coupled to the quantum field . for the uniformly accelerated motion ,
a subtlety in such an analysis arises from the fact that the motion is _ stationary _ , that is , the orbit of a timelike killing vector . because of stationarity , the first - order perturbation theory transition probability over the whole trajectory is infinite , owing to the infinite total proper time . |
9,386 | Suppose that you have an abstract for a scientific paper: we introduce two improvements in the numerical scheme to simulate collision and slow shearing of irregular particles .
first , we propose an alternative approach based on simple relations to compute the frictional contact forces .
the approach improves efficiency and accuracy of the discrete element method ( dem ) when modeling the dynamics of the granular packing .
we determine the proper upper limit for the integration step in the standard numerical scheme using a wide range of material parameters . to this end , we study the kinetic energy decay in a stress controlled test between two particles .
second , we show that the usual way of defining the contact plane between two polygonal particles is , in general , not unique which leads to discontinuities in the direction of the contact plane while particles move . to solve this drawback , we introduce an accurate definition for the contact plane based on the shape of the overlap area between touching particles , which evolves continuously in time . , , granular media , discrete element method , slow deformation , contact forces . 83.10.-y , 45.70.-n , 45.70.cc , 02.60.-x .
And you have already written the first three sentences of the full article: to model the dynamics of granular media a commonly used approach is the well - known discrete element method ( dem ) @xcite .
when applied to slow shearing @xcite the computation of frictional and therefore contact forces between particles may introduce numerical errors that can be larger than the precision of the integration scheme used in dem @xcite .
moreover , if irregular particles are considered typically polygons the definition of the contact plane between touching particles is not straightforward ..
Please generate the next two sentences of the article | [ t ] particles ( green particles ) under shearing of top and bottom boundaries ( blue particles ) .
horizontally periodic boundary conditions are considered and a constant low shear rate is chosen . * ( b ) * illustration of two overlapping particles , where the overlap region @xmath0 between particles fully characterizes the contact force @xmath1.,width=529 ] in this paper we propose an approach to compute the tangential contact force with the same numerical precision as the normal force . |
9,387 | Suppose that you have an abstract for a scientific paper: neutrino flavour oscillations in a nonuniformly moving matter are considered . the neutrino oscillation resonance condition in presence of matter , in the most general case when matter is moving with acceleration ,
is derived for the first time .
we predict that the effect of matter acceleration can have significant influence on neutrino oscillations pattern in different astrophysical environments .
in this short note we generalize our previous studies @xcite on neutrino flavour oscillations in an uniformly moving matter to the case when matter moves with acceleration .
consider two flavour ( electron and muon ) neutrino oscillations in nonuniformly moving matter .
the effective lagrangian of neutrino interactions with background matter can be expressed in the form @xmath0 where @xmath1 is the fermi constant , @xmath2 is the speed of matter , @xmath3 and @xmath4 and @xmath5 for the electron and muon neutrino correspondingly . here
@xmath6 is the electron number density in the reference frame for which the total speed of matter is zero .
note that we consider the matter composed of neutrons , protons and electrons .
obviously , neutrons and protons do not influence the oscillations . for the effective hamiltonian of neutrino flavour states evolution
we obtain @xmath7 where @xmath8 , @xmath9 is the vacuum mixing angle , @xmath10 is the neutrino energy and @xmath11 is the angle between the speed of matter and the direction of neutrino propagation ( it is supposed that the neutrino is propagating along @xmath12 direction ) . in the adiabatic approximation
the oscillation probability has the usual form @xmath13 , where the effective mixing angle @xmath14 and oscillation length @xmath15 are determined by the elements @xmath16 of the evolution hamiltonian ( [ h ] ) .
the straightforward calculations yields the neutrino flavour oscillations resonance condition @xcite @xmath17 in the considered case the neutrino oscillations probability gets its maximum value in a set of points....
And you have already written the first three sentences of the full article: this work has been supported by rfbr grants 14 - 02 - 00914 , 14 - 02 - 31816 ..
Please generate the next two sentences of the article | |
9,388 | Suppose that you have an abstract for a scientific paper: the effective interactions which violate a lepton flavor accompanied with neutrinos ( nlfv ) are considered .
such a new physics effect is expected to be measured in future neutrino oscillation experiments with long baseline .
they are induced by radiative correction in the framework of the minimal supersymmetric standard model with right - handed neutrinos .
we numerically evaluate the size of the couplings for nlfv interactions in this framework .
the slepton mixing is not only the origin of the lepton flavor violation in the charged lepton sector ( clfv ) but also that of the nlfv .
we find that the nlfv couplings are strongly correlated with the corresponding clfv process , and they are constrained at @xmath0 times smaller than the standard four - fermi couplings . .
And you have already written the first three sentences of the full article: numerous observations on neutrinos from the sun@xcite , the atmosphere@xcite , the reactor@xcite , and the accelerator@xcite suggest that neutrinos are massive and hence there are mixings in the lepton sector .
this fact means that the standard model ( sm ) has to be extended so that the neutrino masses and the lepton mixings are introduced into the model .
lots of models to explain those experimental results have been proposed . among them.
Please generate the next two sentences of the article | , a model with the seesaw mechanism@xcite has a promising attribute , in which tiny neutrino masses are naturally induced .
neutrino experiments also have revealed that the mixings in the lepton sector are much larger than those in the quark sector . |
9,389 | Suppose that you have an abstract for a scientific paper: this paper shows that the rnyi information dimension ( rid ) of an i.i.d . sequence of mixture random variables polarizes to the extremal values of 0 and 1 ( fully discrete and continuous distributions ) when transformed by an hadamard matrix .
this provides a natural counter - part over the reals of the entropy polarization phenomenon over finite fields .
it is further shown that the polarization pattern of the rid is equivalent to the bec polarization pattern , which admits a closed form expression .
these results are used to construct universal and deterministic partial hadamard matrices for analog to analog ( a2a ) compression of random i.i.d .
signals .
in addition , a framework for the a2a compression of multiple correlated signals is developed , providing a first counter - part of the slepian - wolf coding problem in the a2a setting .
rnyi information dimension , polarization , information preserving matrices , analog compression , distributed analog compression , compressed sensing . .
And you have already written the first three sentences of the full article: analog to analog ( a2a ) compression of signals has recently gathered interest in information theory @xcite . in a2a compression , a high dimensional analog signal @xmath0
is encoded into a lower dimensional analog signal @xmath1 .
the goal is to design the encoding so as to preserve in @xmath2 all the information about @xmath3 , and to obtain successful decoding for a given distortion measure like mse or error probability . in particular ,.
Please generate the next two sentences of the article | the encoding may be corrupted by noise .
it is worth mentioning that when the alphabet of @xmath4 and @xmath5 is finite , this framework falls into traditional topics of information theory such as lossless and lossy data compression , or joint source - channel coding . |
9,390 | Suppose that you have an abstract for a scientific paper: the halo region of m31 exhibits a startling level of stellar inhomogeneities , the most prominent of which is the `` giant southern stream '' . our previous analysis indicates that this stream , as well as several other observed features , are products of the tidal disruption of a _ single _ satellite galaxy with stellar mass @xmath0 less than 1 gyr ago . here we show that the specific observed morphology of the stream and halo debris favors a cold , rotating , disk - like progenitor over a dynamically hot , non - rotating one .
these observed characteristics include the asymmetric distribution of stars along the stream cross - section and its metal - rich core / metal - poor sheath structure .
we find that a disk - like progenitor can also give rise to arc - like features on the minor axis at certain orbital phases that resemble the recently discovered minor - axis `` streams '' , even reproducing the lower observed metallicity of these streams .
though interpreted by the discoverers as new , independent tidal streams , our analysis suggests that these minor - axis streams may alternatively arise from the progenitor of the giant southern stream .
overall , our study points the way to a more complete reconstruction of the stream progenitor and its merger with m31 , based on the emerging picture that most of the major inhomogeneities observed in the m31 halo share a common origin with the giant stream . .
And you have already written the first three sentences of the full article: the relative proximity of the andromeda galaxy ( m31 ) and the global perspective from our external vantage point make m31 an excellent laboratory for studying the stellar halos of large galaxies . resolved stellar maps of m31 s halo , assembled over the past decade , have revealed highly complex inhomogeneities , the most striking of which is the giant southern stream ( gss ) , extending @xmath1 away from m31 s center in the southeast direction ( * ? ? ?
* ; * ? ? ?
* ; * ? ? ?.
Please generate the next two sentences of the article | * ; * ? ? ?
* hereafter i07 ) and falling towards m31 s center with relative radial velocities as high as @xmath2 @xcite . |
9,391 | Suppose that you have an abstract for a scientific paper: we consider the resonant generation of an electron
positron pair by two polarized photons to arbitrarily low landau levels .
the resonance occurs when the energy of one photon exceeds the one - photon generation threshold , and the energy of the other photon is multiple to the spacing between the levels .
the cross section of the process is determined taking into account the spins of particles .
the order of magnitude of the cross section is the highest when the magnetic moments of the particles are oriented along the magnetic field .
_ j. exp .
theor . phys . *
121*(5 ) 813 ( 2015 ) ; _ * doi : * 10.1134/s1063776115110126 .
And you have already written the first three sentences of the full article: processes accompanying ion collisions continue toattract considerable attention due to the advances in accelerator technology .
in particular , a new facility for antiproton and ion research ( fair ) is being constructed based on the gsi helmholtz center for heavy ion research at darmstadt , germany @xcite .
experiments with heavy ions open wide prospects for the verification of quantum electrodynamics in strong magnetic fields ..
Please generate the next two sentences of the article | the generation of an electron - positron pair upon collisions of ions is one of the most interesting processes .
this process was considered for the first time by landau and lifshitz @xcite and was later studied in detail in the high energy range as well as for low - energy collisions ( see , for example , @xcite and references therein ) . in the latter case |
9,392 | Suppose that you have an abstract for a scientific paper: we report absolutely calibrated measurements of diffuse radio emission between 90 and 190 mhz from the experiment to detect the global eor signature ( edges ) .
edges employs a wide beam zenith - pointing dipole antenna centred on a declination of @xmath0 .
we measure the sky brightness temperature as a function of frequency averaged over the edges beam from 211 nights of data acquired from july 2015 to march 2016 .
we derive the spectral index , @xmath1 , as a function of local sidereal time ( lst ) and find @xmath20.02 between 0 and 12 h lst .
when the galactic centre is in the sky , the spectral index flattens , reaching @xmath30.02 at 17.7 h. the edges instrument is shown to be very stable throughout the observations with night - to - night reproducibility of @xmath4 < 0.003 . including systematic uncertainty , the overall uncertainty of @xmath1 is 0.02 across all lst bins .
these results improve on the earlier findings of @xcite by reducing the spectral index uncertainty from 0.10 to 0.02 while considering more extensive sources of errors .
we compare our measurements with spectral index simulations derived from the global sky model ( gsm ) of @xcite and with fits between the @xcite 45 mhz and @xcite 408 mhz maps .
we find good agreement at the transit of the galactic centre .
away from transit , the gsm over - predict by 0.05
< @xmath5 < 0.12 , while the 45 - 408 mhz fits over - predict by @xmath6 < 0.05 . [ firstpage ] dark ages , reionisation , first stars - instrumentation : miscellaneous - galaxy : structure .
And you have already written the first three sentences of the full article: the low - frequency radio sky spectrum between 50 and 200 mhz is a key area of interest because experiments seeking to detect redshifted 21 cm radiation from neutral hydrogen gas during the epoch of reionization ( eor ) and earlier eras of first light and x - ray heating must subtract astrophysical foregrounds in these frequencies to high - precision . at these frequencies ,
the sky is mostly dominated by galactic synchrotron radiation but also contains contributions from supernova remnants and extragalactic radio sources .
there are two approaches to detecting the redshifted 21 cm signal ..
Please generate the next two sentences of the article | the first approach is targeted by interferometeric arrays , such as the murchison widefield array ( mwa ; @xcite ) , the precision array to probe the epoch of reionization ( paper ; @xcite ) , the hydrogen epoch of reionization array ( hera ; @xcite ) , the low - frequency array ( lofar ; @xcite ) , and the low - frequency aperture array component of the square kilometer array ( ska ; @xcite ) .
these arrays aim to measure spatial fluctuations in the sky brightness temperature on arcminute and degree scales resulting from variations in the density , ionisation , and temperature of the intergalactic medium ( igm ) above redshift @xmath7 ( below 200 mhz ) . |
9,393 | Suppose that you have an abstract for a scientific paper: the design for the proto type of the shanghai laser electron gamma source ( slegs ) at the shanghai synchrotron radiation facility ( ssrf ) is introduced .
some detailed descriptions for design of related instruments are provided .
the proto type can produce x - ray with energy of 10 kev order .
a description of the kinematics of compton backscattering mechanism and the related simulation results are presented and discussed .
the backgrounds from dipole magnet and bremsstrahlung are estimated and the signal - noise ratio is also given .
, , , , , , , , , , , , , , compton backscattering , 100 mev linac , co@xmath0 laser , x - ray 13.60.fz , 41.60.ap , 41.75.ht , 42.55.lt , 07.85.fv .
And you have already written the first three sentences of the full article: with the improvement of accelerator technology , various photon sources around the world are set up based on laser compton scattering process @xcite , which possesses several advantages , such as rather flat energy distribution with small spreading and high linear- or circular - polarization @xcite .
the shanghai synchrotron radiation facility ( ssrf ) is designed for the advanced third generation moderate energy synchrotron radiation facility @xcite .
the synchrotron radiation ray produced from the ssrf covers a broad wave band from far infrared to hard x - ray ..
Please generate the next two sentences of the article | it has a low emittance of moderate energy electrons .
the shanghai laser electron gamma source ( slegs ) will be built at one of the straight sections of the ssrf . |
9,394 | Suppose that you have an abstract for a scientific paper: we demonstrate how a genetic ring oscillator network with quorum sensing feedback can operate as a robust logic gate .
specifically we show how a range of logic functions , namely and / nand , or / nor and xor / xnor , can be realized by the system , thus yielding a versatile unit that can morph between different logic operations .
we further demonstrate the capacity of this system to yield complementary logic operations in parallel .
our results then indicate the computing potential of this biological system , and may lead to bio - inspired computing devices . .
And you have already written the first three sentences of the full article: the operation of any computing device is necessarily a physical process , and this fundamentally determines the possibilities and limitations of the computing machine .
a common thread in the history of computers is the exploitation and manipulation of different natural phenomena to obtain newer forms of computing paradigms @xcite .
for instance , chaos computing @xcite , neurobiologically inspired computing , quantum computing@xcite , and dna computing@xcite all aim to utilize , at the basic level , some of the computational capabilities inherent in natural systems ..
Please generate the next two sentences of the article | in particular , larger understanding of biological systems has triggered the interesting question : what new directions do bio - systems offer for understanding and implementing computations ?
the broad idea then , is to create machines that benefit from natural phenomena and utilize patterns inherent in systems to encode inputs and subsequently obtain a desired output . |
9,395 | Suppose that you have an abstract for a scientific paper: a collection of the physical observables , related to the electromagnetic properties of a nucleon , to investigate the non perturbative quantum fluctuations in the strong interaction vacuum state under the influence of at least one close by ( in energy density ) color superconducting phase found in several qcd motivated model calculations , are studied .
it is shown that the spontaneous breaking of the electromagnetic gauge symmetry in the color superconducting phase of strong interaction can result in relatively clean signals in high energy processes , especially in the semi - leptonic deep inelastic scattering ones , due to a kind of electromagnetic induced strong interaction .
a new type of mechanism , which is a generalization of the higgs one , through which the local electromagnetic gauge symmetry is spontaneously broken by a spontaneous breaking of the global baryon ( nucleon ) number conservation , is revealed . a model independent assessment of the question of how far is the color superconducting phase of the strong interaction from its vacuum phase is made by studying currently available experimental data on the electromagnetic responses of a nucleon at high energies .
it is shown that based on our current knowledge about a nucleon , it is quite likely that there is at least one color superconducting phase for the strong interaction that is close enough to the vacuum state so that its effects can even be seen in high energy processes besides heavy ion collisions .
# 1 # 1 # 1#2| .
And you have already written the first three sentences of the full article: diquark condensation in the strong interaction ground states at asymptotically high baryon density is a very like possibility @xcite since the dominant one gluon exchange interaction between quarks in such a situation is attractive in the color triplet channel which causes the bcs instability @xcite at the fermi surface for the quarks . at zero and low densities compared to the nuclear saturation
one , the study of the phenomenon in qcd , now called _ color superconductivity _ , is more difficult due to the fact that one has to deal with non - perturbative and finite density effects .
it is quite apparent that the strong interaction vacuum is not color superconducting at the present day condition in a large and uniform region in space since color is known to be confined ..
Please generate the next two sentences of the article | the following question can nevertheless be asked : _ how far away ( in energy density ) is certain type of metastable color superconducting phase , called a virtual phase , of the hadronic vacuum from the stable one at the present day condition?_. it is speculated in refs .
@xcite that certain kind of color superconducting phase exists , which has an energy density close to that of the normal phase for the strong interaction vacuum in which the chiral symmetry is spontaneously broken down . |
9,396 | Suppose that you have an abstract for a scientific paper: we perform _ ab initio _ quantum monte carlo ( qmc ) simulations of the warm dense uniform electron gas in the thermodynamic limit . by combining qmc data with linear response theory we are able to remove finite - size errors from the potential energy over the entire warm dense regime , overcoming the deficiencies of the existing finite - size corrections by brown _
et al . _ [ prl * 110 * , 146405 ( 2013 ) ] .
extensive new qmc results for up to @xmath0 electrons enable us to compute the potential energy @xmath1 and the exchange - correlation free energy @xmath2 of the macroscopic electron gas with an unprecedented accuracy of @xmath3 . a comparison of our new data to the recent parametrization of @xmath2 by karasiev _
et al . _ [ prl * 112 * , 076403 ( 2014 ) ] reveals significant inaccuracies of the latter .
the uniform electron gas ( ueg ) , consisting of electrons on a uniform neutralizing background , is one of the most important model systems in physics . besides being a simple model for metals
, the ueg has been central to the development of linear response theory and more sophisticated perturbative treatments of solids , the formulation of the concepts of quasiparticles and elementary excitations , and the remarkable successes of density functional theory . the practical application of ground - state density functional theory in condensed matter physics , chemistry and materials science rests on a reliable parametrization of the exchange - correlation energy of the ueg @xcite , which in turn is based on accurate quantum monte carlo ( qmc ) simulation data @xcite . however , the charged quantum matter in astrophysical systems such as planet cores and white dwarf atmospheres @xcite is at temperatures way above the ground state , as are inertial confinement fusion targets @xcite , laser - excited solids @xcite , and pressure induced modifications of solids , such as insulator - metal transitions @xcite .
this unusual regime , in which strong ionic correlations coexist with electronic....
And you have already written the first three sentences of the full article: we are grateful to jan vorberger for providing the montroll - ward and e@xmath98 data shown in fig .
[ intro_pic ] .
this work was supported by the deutsche forschungsgemeinschaft via project bo1366 - 10 and via sfb tr-24 project a9 as well as grant shp00015 for cpu time at the norddeutscher verbund fr hoch- und hchstleistungsrechnen ( hlrn ) ..
Please generate the next two sentences of the article | ts acknowledges the support of the us doe / nnsa under contract no .
de - ac52 - 06na25396 . |
9,397 | Suppose that you have an abstract for a scientific paper: we consider the influence of quenched noise upon interface dynamics in 2d and 3d capillary rise with rough walls by using phase - field approach , where the local conservation of mass in the bulk is explicitly included . in the 2d case the disorder is assumed to be in the effective mobility coefficient , while in the 3d case we explicitly consider the influence of locally fluctuating geometry along a solid wall using a generalized curvilinear coordinate transformation . to obtain the equations of motion for meniscus and contact lines ,
we develop a systematic projection formalism which allows inclusion of disorder . using this formalism
, we derive linearized equations of motion for the meniscus and contact line variables , which become local in the fourier space representation .
these dispersion relations contain effective noise that is linearly proportional to the velocity .
the deterministic parts of our dispersion relations agree with results obtained from other similar studies in the proper limits . however , the forms of the noise terms derived here are quantitatively different from the other studies . .
And you have already written the first three sentences of the full article: the dynamics and roughening of moving interfaces in disordered media has been a subject of great interest in non - equilibrium statistical physics since the 1980s .
relevant examples of physically and technologically important processes include thin film deposition @xcite , fluid invasion in porous media @xcite , and wetting and propagation of contact lines between phase boundaries @xcite .
the understanding of the underlying physics involved in interface roughening is crucial to the control and optimization of these processes ..
Please generate the next two sentences of the article | significant progress in the theoretical study of interface dynamics has been made and a number of theories have been developed @xcite , which in some selected cases agree well with the experimental findings @xcite .
most of the theoretical understanding in this field is based on modeling interface roughening with a local stochastic equation of motion for the single - valued height variable of the interface . |
9,398 | Suppose that you have an abstract for a scientific paper: in this work we study the behaviour of two weakly coupled quantum systems , described by a separable density operator ; one of them is a single oscillator , representing a microscopic system , while the other is a set of oscillators which perform the role of a _ reservoir _ in thermal equilibrium . from the liouville - von neumann equation for the reduced density operator
, we devise the master equation that governs the evolution of the microscopic system , incorporating the effects of temperature via thermofield dynamics formalism by suitably redefining the vacuum of the macroscopic system . as applications
, we initially investigate the behaviour of a fermi oscillator in the presence of a heat bath consisting of a set of fermi oscillators and that of an atomic two - level system interacting with a scalar radiation field , considered as a _ reservoir _
, by constructing the corresponding master equation which governs the time evolution of both sub - systems at finite temperature .
finally , we calculate the energy variation rates for the atom and the field , as well as the atomic population levels , both in the inertial case and at constant proper acceleration , considering the two - level system as a prototype of an unruh detector , for admissible couplings of the radiation field . .
And you have already written the first three sentences of the full article: the interest in the study of quantum many - body systems from the modern standpoint of quantum field theories @xcite has grown since the 1960 s , ranging from low to extremely high energy and temperature regimes @xcite . in 1975 ,
takahashi and umezawa proposed an operator - based formalism called thermofield dynamics ( tfd ) @xcite in order to describe quantum systems at finite temperature in thermal equilibrium . in the same year
the discovery of the hawking effect @xcite , from the black hole thermal radiation , was one of the most innovative results in quantum field theory in curved space - time ..
Please generate the next two sentences of the article | later on , davis @xcite suggested that a similar effect would occur even in a flat space - time . in 1976 , unruh @xcite showed that the essential characteristics of the hawking effect were contained in a simpler situation : an accelerated detector , would be excited by particles in vacuum , property known as the unruh effect .
this discovery of the hawking - unruh effect has inspired many researchers , generating since them a series of important results , @xcite . |
9,399 | Suppose that you have an abstract for a scientific paper: we report on the realization of an open plane - concave fabry - prot resonator with a mode volume below @xmath0 at optical frequencies .
we discuss some of the less common features of this new microcavity regime and show that the ultrasmall mode volume allows us to detect cavity resonance shifts induced by single nanoparticles even at quality factors as low as @xmath1 . being based on low - reflectivity micromirrors fabricated on a silicon cantilever , our experimental arrangement provides broadband operation , tunability of the cavity resonance , lateral scanning and promise for optomechanical studies . .
And you have already written the first three sentences of the full article: starting with the question of whether the excited - state lifetime of an atom can be modified , physicists have continuously explored ways to engineer the radiative properties of quantum emitters .
the first experimental studies were performed in the near field of flat interfaces @xcite , but the change of spontaneous emission is commonly associated with purcell s prediction that a cavity of quality factor @xmath2 and mode volume @xmath3 can accelerate the radiation of a dipolar transition by @xmath4 folds , where @xmath5 is the wavelength in the corresponding medium @xcite . following this recipe ,
many clever resonator schemes such as high - q open fabry - prot cavities ( fpc ) , monolithic fpcs in form of pillars , whispering gallery mode resonators and photonic crystal structures have been investigated for realizing large purcell factors @xcite ..
Please generate the next two sentences of the article | nevertheless , sizable modifications of the spontaneous emission process remain nontrivial because no cavity design has succeeded in providing all the decisive ingredients of large @xmath2 , small @xmath3 ( ideally down to its fundamental value of the order of @xmath6 ) , a facile way of tuning the cavity resonance , and compatibility with emitters of different materials . of the various cavity geometries ,
open fpcs remain particularly attractive because they nicely lend themselves to the latter two criteria . |
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