id
int64 0
203k
| input
stringlengths 66
4.29k
| output
stringlengths 0
3.83k
|
|---|---|---|
6,000 | Suppose that you have an abstract for a scientific paper: in oncology , positron emission tomography imaging is widely used in diagnostics of cancer metastases , in monitoring of progress in course of the cancer treatment , and in planning radiotherapeutic interventions .
accurate and reproducible delineation of the tumor in the positron emission tomography scans remains a difficult task , despite being crucial for delivering appropriate radiation dose , minimizing adverse side - effects of the therapy , and reliable evaluation of treatment . in this piece of research we attempt to solve the problem of automated delineation of the tumor using 3d implementations of the spatial distance weighted fuzzy c - means , the deep convolutional neural network and a dictionary model .
the methods , in diverse ways , combine intensity and spatial information . .
And you have already written the first three sentences of the full article: positron emission tomography ( pet ) is a nuclear imaging technique used to monitor metabolic activity of the body .
the pet system detects gamma rays generated when electrons collide with positrons emitted by radiolabelled biologically active molecules , such as fluorodeoxyglucose . in oncology , pet is widely used in diagnostics of cancer metastases , in monitoring of progress in course of the cancer treatment , and also in planning radioterapheutic interventions . in the last case , pet scans , often in combination with computer tomography ( ct ) scans ,
are used to delineate biologically active parts of tumors , which are then treated with ionizing radiation ..
Please generate the next two sentences of the article | accurate delineation of the tumor is crucial for delivering appropriate radiation dose and minimizing adverse side - effects of the therapy .
however , the problem is not trivial as evidenced by substantial intra- and interobserver variations when delineation is performed manually by experts@xcite |
6,001 | Suppose that you have an abstract for a scientific paper: we show that a hairy black hole solution can provide a holographically _ dual _ description of quark confinement .
there exists a one - parameter sensible metric which receives the backreaction of matter contents in the holographic action , where the scalar and gauge field are responsible for the condensation of chromomagnetic monopoles .
this model features a preconfining phase triggered by second - order monopole condensation and a first - order confinement / deconfinement phase transition . to confirm the confinement ,
the quark - antiquark potential is calculated by probing a qcd string in both phases . at last ,
contribution from kaluza - klein monopoles in the confining phase is discussed .
the holographic correspondence between a gravitational theory in the bulk and a quantum field theory on the boundary , first emerged under the anti - de sitter / conformal field theory ( ads / cft ) correspondence @xcite , has been proved useful to study condensed matter phenomena . in particular , the authors in @xcite proposed a gravity model in which abelian symmetry of higgs is spontaneously broken by the existence of black hole , also known as hairy black hole .
this mechanism was incorporated in the model of superconductivity and critical temperature was observed @xcite .
this model was later studied in the presence of magnetic field @xcite and with full backreaction @xcite .
on the other hand , the ads / cft analogy has also explained many qualitative and quantitative features of confining gauge theories like qcd , either by engineering branes and strings in the ten dimensional string theory @xcite , or by bottom - up construction of a randall - sundrum like background @xcite .
in particular , holographic models of deconfinement were first discussed in the sakai - sugimoto model at finite temperature@xcite and the hard / soft wall model@xcite . in all cases , the confinement / deconfinement transition is identified as the first - order hawking - page phase transition , where....
And you have already written the first three sentences of the full article: the authors are grateful to the useful discussion with hsien - chung kao and shoichi kawamoto in the early stage of this work .
wyw would like to thank the warm hospitality received in the ustc , china when part of this work was presented in the east asia joint workshop on fields and strings and insightful discussion with sang - jin sin .
this work is supported in parts by the chung yuan christian university , the taiwan s ministry of science and technology ( grant no ..
Please generate the next two sentences of the article | 102 - 2112-m-033 - 003-my4 ) and the national center for theoretical science .
in this appendix , we will derive the relation among parameters @xmath74 in the warping factors : one can freely absorb the combination @xmath80 into redefinition of @xmath14 , that is to set @xmath81 . |
6,002 | Suppose that you have an abstract for a scientific paper: we present a very brief overview of some recent @xmath0-ray observations of selected blazars to reveal an indication for a considerable or even dominant contribution of secondary @xmath0-rays from electromagnetic cascades to the observable spectra in the 1500 @xmath1 energy range . .
And you have already written the first three sentences of the full article: the universe is filled by light .
there are two principal sources of such photons the cosmic microwave background ( cmb ) and the extragalactic background light ( ebl ) .
while cmb properties are quite well measured and theoretically understood for more than 20 years ( e.g. @xcite ) , many ebl models with widely different parameters were developed @xcite@xcite ; for instance , the total ebl intensity for these models differs by more than a factor of two @xcite . comparatively recently.
Please generate the next two sentences of the article | , however , some of these ebl models started to converge , at least in the 0.510 @xmath2 wavelength region ( e.g. , @xcite and @xcite ) .
high - energy @xmath0-rays with primary energy @xmath3/\epsilon ) [ tev]$ ] get absorbed @xcite@xcite ( @xmath4 ) on ebl and cmb photons with energy @xmath5 , reaching maximum cross section at @xmath6/\epsilon ) [ tev]$ ] @xcite . |
6,003 | Suppose that you have an abstract for a scientific paper: we present a hartree - fock study that incorporates the effects of landau level mixing and screening due to filled levels into the computation of energies and states of quasiparticles in quantum hall ferromagnets .
we use it to construct a phase diagram for skyrmion stability as a function of magnetic field and zeeman coupling strengths .
we find that landau level mixing tends to favor spin - polarized quasiparticles , while finite thickness corrections favor skyrmions .
our studies show that skyrmion stability in high landau levels is very sensitive to the way in which electron - electron interactions are modified by finite thickness , and indicate that it is crucial to use models with realistic short distance behavior to get qualitatively correct results .
we find that recent experimental evidence for skyrmions in higher landau levels can not be explained within our model .
0.08 in .
And you have already written the first three sentences of the full article: it has been recognized that exotic magnetic excitations known as skyrmions may exist @xcite in a two - dimensional electron gas in a strong homogeneous magnetic field ( quantum hall system ) near spin polarized groundstates .
these are excitations of a two - dimensional spontaneous ferromagnet , the physics of which is relevant to this system ( despite the presence of a strong magnetic field ) , because of the small land @xmath0-factor in gaas systems ( where most experiments take place ) , which makes the zeeman coupling very small compared to other energy scales ( coulomb interaction , cyclotron energy ) in the problem .
skyrmions are spin configurations with a non - trivial winding number ( pontryagin index ) ..
Please generate the next two sentences of the article | they were first discussed in the context of four - dimensional field theories @xcite , and were later recognized as states occurring in the non - linear sigma model description of two - dimensional ferromagnets @xcite . for filling factors @xmath1 close to one ( @xmath2 is the number of electrons and @xmath3 the number of magnetic flux quanta penetrating the system ) , these turn out to be the lowest energy quasiparticles under typical experimental circumstances .
skyrmions can thus be introduced into the groundstate by adding or removing charge from the system . |
6,004 | Suppose that you have an abstract for a scientific paper: the origin of the martian methane is still poorly understood .
a plausible explanation is that methane could have been produced either by hydrothermal alteration of basaltic crust or by serpentinization of ultramafic rocks producing hydrogen and reducing crustal carbon into methane .
once formed , methane storage on mars is commonly associated with the presence of hidden clathrate reservoirs . here
, we alternatively suggest that chabazite and clinoptilolite , which belong to the family of zeolites , may form a plausible storage reservoir of methane in the martian subsurface .
because of the existence of many volcanic terrains , zeolites are expected to be widespread on mars and their global equivalent layer may range up to more than @xmath01 km , according to the most optimistic estimates .
if the martian methane present in chabazite and clinoptilolite is directly sourced from an abiotic source in the subsurface , the destabilization of a localized layer of a few millimeters per year may be sufficient to explain the current observations .
the sporadic release of methane from these zeolites requires that they also remained isolated from the atmosphere during its evolution .
the methane release over the ages could be due to several mechanisms such as impacts , seismic activity or erosion .
if the methane outgassing from excavated chabazite and/or clinoptilolite prevails on mars , then the presence of these zeolites around gale crater could explain the variation of methane level observed by mars science laboratory .
mars , mars , atmosphere , mars , surface , mineralogy , astrobiology .
And you have already written the first three sentences of the full article: the origin of the martian methane ( ch@xmath1 ) is still poorly understood . despite the fact that the presence of ch@xmath1 remains under debate ( zahnle et al .
2011 ; zahnle 2015 ) , detections have been claimed at the 1060 parts per billion by volume ( ppbv ) level in mars atmosphere from space and ground - based observations at the end of the 90s and during the following decade ( formisano et al . , 2004 ;
krasnopolsky et al . 2004 ; mumma et al ..
Please generate the next two sentences of the article | 2009 ; fonti and marzo 2010 ) .
recent observations suggest a ch@xmath1 atmospheric abundance of @xmath010 ppbv , and in some cases no or little ch@xmath1 with an upper limit of @xmath07 ppbv in 20092010 , during mars northern spring ( krasnopolsky 2012 ; villanueva et al . |
6,005 | Suppose that you have an abstract for a scientific paper: we present a combinatorial procedure , based on the @xmath0-graph of the coxeter group , which shows that the graded dimension of the stalks of intersection cohomology complexes of certain schubert varieties is independent of the characteristic of the coefficient field .
our procedure exploits the existence and uniqueness of parity sheaves . in particular
we are able to show that the characters of all intersection cohomology complexes with coefficients in a field on the flag variety @xmath1 of type @xmath2 for @xmath3 are given by kazhdan - lusztig basis elements . by results of soergel
, this implies a part of lusztig s conjecture for @xmath4 with @xmath5 .
we also give examples where our techniques fail . in the appendix by tom
braden examples are given of intersection cohomology complexes on the flag varities of @xmath6 and @xmath7 whose stalks have different graded dimension in characteristic 2 . .
And you have already written the first three sentences of the full article: let @xmath8 be a field of characteristic @xmath9 .
let @xmath10 be a reducive algebraic group over @xmath11 , @xmath12 a borel subgroup and @xmath13 the weyl group and its simple reflections .
denote by @xmath14 the bounded derived category of sheaves of @xmath8-vector spaces on @xmath1 constructible along @xmath15-orbits . in @xmath14 there.
Please generate the next two sentences of the article | exist the intersection cohomology sheaves @xmath16 .
these sheaves are a certain extension of the constant sheaf in degree @xmath17 on the bruhat cell @xmath18 to its closure . |
6,006 | Suppose that you have an abstract for a scientific paper: we show that the optical structure of the helical phase of a chiral nematic is naturally associated with the bianchi @xmath0 group manifold , of which we give a full account .
the joets - ribotta metric governing propagation of the extraordinary rays is invariant under the simply transitive action of the universal cover @xmath1 of the three dimensional euclidean group of two dimensions .
thus extraordinary light rays are geodesics of a left - invariant metric on this bianchi type @xmath0 group .
we are able to solve by separation of variables both the wave equation and the hamilton - jacobi equation for this metric .
the former reduces to mathieu s equation and the later to the quadrantal pendulum equation .
we discuss maxwell s equations for uniaxial optical materials where the configuration is invariant under a group action and develop a formalism to take advantage of these symmetries .
the material is not assumed to be impedance matched , thus going beyond the usual scope of transformation optics .
we show that for a chiral nematic in its helical phase maxwell s equations reduce to a generalised mathieu equation .
our results may also be relevant to helical phases of some magnetic materials and to light propagation in certain cosmological models . .
And you have already written the first three sentences of the full article: recent years have seen a growing interest in the application of the geometrical ideas originally developed for studying einstein s theory of general relativity to other areas of physics , such as condensed matter physics .
the motivation is both the theoretical aim of developing the mathematical tools capable of dealing with as wide a range of physical problems as possible , and the desire to construct laboratory analogues of the exotic conditions which general relativity allows , but which are likely ever to remain inaccessible to direct experimental investigation .
this in turn may provide a stimulus for further laboratory investigations , possibly resulting in the discovery of new physical effects . in the present article we shall pursue this direction by demonstrating how the mathematical formalism of lie groups , which is of widespread use in general relativity and high energy physics @xcite , can be harnessed to study optical properties of symmetrical phases of matter ..
Please generate the next two sentences of the article | we develop a formalism allowing the symmetries of an electromagnetic medium to be directly exploited in solving maxwell s equations . when considering symmetries in classical mechanics , the discussion is simplified by passing to the lagrangian or hamiltonian picture .
we present a formalism which similarly makes symmetries manifest for maxwell s equations . in order to motivate and illuminate the development of this formalism , we consider the example of light propagation in chiral nematic liquid crystals . |
6,007 | Suppose that you have an abstract for a scientific paper: we use numerical simulations in a @xmath0cdm cosmology to model density profiles in a set of sixteen dark matter haloes with resolutions of up to seven million particles within the virial radius .
these simulations allow us to follow robustly the formation and evolution of the central cusp over a large mass range of 10@xmath1 to 10@xmath2 @xmath3 , down to approximately 0.5@xmath4 of the virial radius , and from redshift 5 to the present , covering a larger range in parameter space than previous works .
we confirm that the cusp of the density profile is set at redshifts of two or greater and remains remarkably stable to the present time , when considered in non - comoving coordinates .
motivated by the diversity and evolution of halo profile shapes , we fit our haloes to the two parameter profile , @xmath5^{3-\gamma}}$ ] , where the steepness of the cusp is given by the asymptotic inner slope parameter , @xmath6 , and its radial extent is described by the concentration parameter , @xmath7 ( with @xmath7 defined as the virial radius divided by the concentration radius ) . in our simulations , we find @xmath8log@xmath9 for haloes of @xmath10 to @xmath11 , with a large scatter of @xmath12 , where @xmath13 is the redshift dependent characteristic mass of collapsing haloes ; and @xmath14 , with a large @xmath15 dependent scatter roughly equal to @xmath16 .
our redshift zero haloes have inner slope parameters ranging approximately from @xmath17 ( i.e. navarro , frenk , & white ) to @xmath18 ( i.e. moore et al . ) , with a median of roughly r@xmath19 .
this two parameter profile fit works well for all types haloes in our simulations , whether or not they show evidence of a steep asymptotic cusp .
we also model a cluster in power law cosmologies of @xmath20 , with @xmath21 ( 0 , -1 , -2 , -2.7 ) . here
we find that the concentration radius and the inner cusp slope are a both function of @xmath22 , with larger concentration radii and shallower cusps for steeper power spectra .
we have....
And you have already written the first three sentences of the full article: the mass distribution of dark matter haloes provides a direct probe of the nature of the dark matter particle , as the inner structure of dark matter haloes is particularly sensitive to the dark matter properties .
for example , warm dark matter should produce lower density halo cores than cold dark matter ( cdm ) because of the phase density ceiling introduced by the non - zero thermal velocity of warm particles ( e.g. tremaine & gunn 1979 ) .
the variation of peak halo phase density with halo mass is also dependent on the `` coldness '' of the dark matter particle ( e.g. lake 1989 and references therein ) ..
Please generate the next two sentences of the article | spectroscopic observations of stellar motions in galaxies , lensing properties and x - ray temperature maps of cluster cores each can provide a measurement of the central dark matter distribution in haloes , albeit with some uncertainty inherent in inferring the dark matter distribution from properties of baryons or baryon dominated regions .
cdm haloes in n - body simulations consistently have a steep central cusp where the density rises as @xmath17 ( navarro , frenk , & white 1996 , 1997 , nfw hereafter ; huss , jain , & steinmetz 1999 ; power et al . |
6,008 | Suppose that you have an abstract for a scientific paper: we investigate decoherence of quantum superpositions induced by gravitational time dilation and spontaneous emission between two atomic levels . it has been shown that gravitational time dilation can be an universal decoherence source . here , we consider decoherence induced by gravitational time dilation only in the situation of spontaneous emission .
then , we obtain that the coherence of particle s position state depends on reference frame due to the time dilation changing the distinguishability of emission photon from two positions of particle .
changing the direction of light field can also result in the difference about the coherence of quantum superpositions . for observing the decoherence effect mainly due to gravitational time dilation
, time - delayed feedback can be utilized to increase the decoherence of particle s superpositions . .
And you have already written the first three sentences of the full article: quantum phenomenon has been observed by numerous experiments on microscopic scales . however , on macroscopic scales , it is difficult to find quantum effects , such as quantum superpositions .
a lot of physicists have been looking up the root of quantum - to - classical transition for decades .
the reason can be divided into two categories : coarsened measurement and decoherence@xcite ..
Please generate the next two sentences of the article | commonly viewpoint is that decoherence plays a prominent role in quantum - to - classical transition .
there are two routes to explain decoherence : one route is that system interacts with external environments , the other is taken in wave function collapse@xcite , which need not external environments . |
6,009 | Suppose that you have an abstract for a scientific paper: we introduce the minimal maximally predictive models ( ) of processes generated by certain hidden semi - markov models .
their causal states are either hybrid discrete - continuous or continuous random variables and causal - state transitions are described by partial differential equations .
closed - form expressions are given for statistical complexities , excess entropies , and differential information anatomy rates .
we present a complete analysis of the of continuous - time renewal processes and , then , extend this to processes generated by unifilar hidden semi - markov models and semi - markov models .
our information - theoretic analysis leads to new expressions for the entropy rate and the rates of related information measures for these very general continuous - time process classes . .
And you have already written the first three sentences of the full article: we are interested in answering two very basic questions about continuous - time , discrete - symbol stochastic processes : * what are their minimal maximally predictive models their ? * what are information - theoretic characterizations of their randomness , predictability , and complexity ? for shorthand , we refer to the former as _ causal architecture _ and the latter as _ informational architecture_. minimal maximally predictive models of discrete - time , discrete - state , discrete - output processes are relatively well understood ; e.g. , see refs .
some progress has been made on understanding minimal maximally predictive models of discrete - time , continuous - output processes ; e.g. , see refs . @xcite .
relatively less is understood about minimal maximally predictive models of continuous - time , discrete - output processes , beyond those with exponentially decaying state - dwell times @xcite ..
Please generate the next two sentences of the article | the following is a first attempt at a remedy that complements the spectral methods developed in ref .
@xcite , as we address the less tractable case of uncountably infinite causal states . |
6,010 | Suppose that you have an abstract for a scientific paper: we present a statistical method to derive the mass functions of open clusters using sky survey data such as the 2 micron all sky survey ( 2mass ) and the guide star catalogue ( gsc ) .
we have used this method to derive the mass functions in the stellar / substellar regime of three young , nearby open clusters , namely ic 348 , @xmath0 orionis and pleiades .
the mass function in the low mass range ( m@xmath1 ) is appreciably flatter than the stellar salpeter function for all three open clusters .
the contribution of objects below 0.5 m@xmath2 to the total mass of the cluster is @xmath340% and the contribution of objects below 0.08 m@xmath2 to the total is @xmath34% .
# 1_#1 _ # 1_#1 _ = # 1 1.25 in .125 in .25 in .
And you have already written the first three sentences of the full article: recent surveys have found a significant population of low - mass stars , brown dwarfs and planetary - mass objects in young open clusters . since low - mass objects evolve little over the lifetime of the universe , the present day mass function of these objects is a good representation of the initial mass function ( imf ) .
the mass function in this low - mass regime is however poorly known due to faintness of these objects and also due to uncertainty in the mass - luminosity relations .
low - mass objects at or below the hydrogen burning mass limit ( hbml ) of 0.08 m@xmath2 are known to be warmer and hence more luminous when young although they cool rapidly and fade with age ( baraffe et al . 1998 ) ..
Please generate the next two sentences of the article | the combination of youth and proximity in some open clusters make them ideal targets for searches of low - mass objects below the hbml particularly at infrared wavelengths . in the present study
we have adopted a statistical approach to determine the mass function ( dn / dm @xmath4 m@xmath5 ) of objects in the mass range @xmath6 to 0.0250.05 m@xmath2 using data of three open clusters namely ic 348 , @xmath0 orionis and pleiades . |
6,011 | Suppose that you have an abstract for a scientific paper: we explore the dark matter and lhc implications of @xmath0 quasi yukawa unification in the framework of supersymmetric models based on the gauge symmetry @xmath1 . the deviation from exact yukawa unification is quantified by a dimensionless parameter @xmath2 ( @xmath3 ) , such that the yukawa couplings at @xmath4 are related by @xmath5 .
in contrast to earlier studies which focused on universal gaugino masses , we consider non - universal gaugino masses at @xmath4 that are compatible with the gauge symmetry @xmath6 .
we perform two independent scans of the fundamental parameter space , one of which employs isajet , while the other uses softsusy interfaced with superiso .
these scans reveal qualitatively similar allowed regions in the parameter space , and yield a variety of neutralino dark matter scenarios consistent with the observations .
these include stau and chargino coannihilation scenarios , the @xmath7resonance scenario , as well as higgsino dark matter solution which is more readily probed by direct detection searches .
the gluino mass is found to be @xmath8 tev , the stop mass is @xmath9 tev , while the first two family squarks and sleptons are of order @xmath10 tev and @xmath11 tev respectively . .
And you have already written the first three sentences of the full article: in an earlier paper @xcite , hereafter referred to as i , we have explored the lhc implications of imposing @xmath0 quasi - yukawa unification ( qyu ) at the grand unification scale ( @xmath12 gev ) .
this modified approach to the third family ( @xmath0 ) yu @xcite can be motivated by the desire to construct realistic supersymmetric models of grand unified theories ( guts ) which also incorporate realistic masses and mixings observed in the matter sector .
for instance , the desired quarks and charged lepton masses for the second family fermion can be incorporated , following @xcite , by including higgs fields in the ( 15,1,3 ) representation of @xmath1 ( 4 - 2 - 2 ) @xcite , which develop a non - zero gut scale vacuum expectation values ( vevs ) ..
Please generate the next two sentences of the article | the third family yukawa couplings receive , in this case , sizable new contributions , and the deviations from exact yu can be stated as follows @xcite : @xmath13 where @xmath2 measures the deviation from the exact yu . restricting the deviation to @xmath14
we refer eq.([qyu ] ) to qyu condition . |
6,012 | Suppose that you have an abstract for a scientific paper: we compute the dynamics and emission of dissipative shells that are subject to a strong compton drag , under simplifying assumptions about the dissipation mechanism . we show that under conditions prevailing in blazars , substantial deceleration is anticipated on sub - parsec and parsec scales in cases of rapid dissipation
. such episodes may be the origin of some of the flaring activity occasionally observed in gamma ray blazars .
the shape of the light curves thereby produced reflects the geometry of the emitting surface if the deceleration is very rapid , or the dynamics of the shell if the deceleration is delayed , or initially more gradual , owing , e.g. , to continuous injection of energy and momentum . .
And you have already written the first three sentences of the full article: the broadband spectrum observed in blazars is dominated by beamed emission produced in relativistic jets that emanate from the central black hole .
these jets propagate through a dense radiative environment , and interact with seed photons that are supplied by extended radiation sources , notably the accretion disk around the black hole , gaseous clouds in the broad line region ( blr ) , and a dusty molecular torus located at larger scales ( see , e.g. , joshi et al .
2014 for a recent account ) ..
Please generate the next two sentences of the article | this interaction should affect the dynamics and emission of the jet .
the primary concern of most previous works ( e.g. , dermer & schlickeiser 1993 , sikora et al . |
6,013 | Suppose that you have an abstract for a scientific paper: we have calculated spectral functions associated with hadronic current correlation functions for vector currents at finite temperature .
we made use of a model with chiral symmetry , temperature - dependent coupling constants and temperature - dependent momentum cutoff parameters .
our model has two parameters which are used to fix the magnitude and position of the large peak seen in the spectral functions . in our earlier work ,
good fits were obtained for the spectral functions that were extracted from lattice data by means of the maximum entropy method ( mem ) . in the present work
we extend our calculations and provide values for the three - momentum dependence of the vector correlation function at @xmath0 .
these results are used to obtain the correlation function in coordinate space , which is usually parametrized in terms of a screening mass .
our results for the three - momentum dependence of the spectral functions are similar to those found in a recent lattice qcd calculation for charmonium [ s. datta , f. karsch , p. petreczky and i. wetzorke , hep - lat/0312037 ] . for a limited range
we find the exponential behavior in coordinate space that is usually obtained for the spectral function for @xmath1 and which allows for the definition of a screening mass . .
And you have already written the first three sentences of the full article: in a number of recent works [ 1 - 3 ] we have calculated various hadronic correlation functions and compared our results to results obtained in lattice simulations of qcd [ 4 - 6 ] .
the lattice results for the correlators , @xmath2 , may be used to obtain the corresponding spectral functions , @xmath3 , by making use of the relation g ( , t)=_0^d ( , t ) k ( , , t),where k ( , , t)=.the procedure to obtain @xmath3 from the knowledge of @xmath2 makes use of the maximum entropy method ( mem ) [ 7 - 9 ] , since @xmath2 is only known at a limited number of points . in our studies of meson spectra at @xmath4 and at @xmath5 we have made use of the nambu jona - lasinio ( njl ) model .
the lagrangian of the generalized njl model we have used in our studies is l&=&(i - m^0)q+_i=0 ^ 8 [ ( ^i q)^2 + ( i _ 5 ^i q)^2 ] + & -&_i=0 ^ 8 [ ( ^i_q)^2 + ( ^i_5_q)^2 ] + & + & + + l_conf . here , @xmath6 is a current quark mass matrix , @xmath6=diag@xmath7 ..
Please generate the next two sentences of the article | the @xmath8 are the gell - mann ( flavor ) matrices and @xmath9 , with @xmath10 being the unit matrix .
the fourth term is the t hooft interaction and @xmath11 represents the model of confinement used in our studies of meson properties . in the study of hadronic current correlators |
6,014 | Suppose that you have an abstract for a scientific paper: rare leptonic kaon and pion decays @xmath0 can be used to probe a dark photon of mass @xmath1 mev , with the background coming from the mediation of a virtual photon .
this is most relevant for the 16.7-mev dark photon proposed to explain a 6.8@xmath2 anomaly recently observed in @xmath3be transitions by the atomki collaboration .
we evaluate the reach of future experiments for different scenarios of how the dark photon couples with the standard model particles , and show that a great portion of the preferred 16.7-mev dark photon parameter space can be decisively probed .
we also show the use of angular distributions to further distinguish the signal from the background . .
And you have already written the first three sentences of the full article: the search of new gauge interactions has been of great interest .
such efforts help us understand whether there is any other new force in nature and how it fits to the grand picture of particle physics . if found , there is also a possibility that the new force carrier provides a portal between the standard model ( sm ) visible sector and a hidden sector involving new dynamics and matter contents . in the simplest scenario ,
such a new vector boson may have an origin from some extra @xmath4 gauge symmetry , under which some particles in both visible and hidden sectors are charged ..
Please generate the next two sentences of the article | it may even have kinetic or mass mixing with the sm photon or @xmath5 boson field to facilitate the mediation .
after its symmetry breaking , as is often assumed , the @xmath4 gauge boson acquires a mass and is commonly called the @xmath6 boson if it is heavier than the electroweak scale or the dark photon if it is lighter . |
6,015 | Suppose that you have an abstract for a scientific paper: we review the conformal equivalence in describing the background expansion of the universe by @xmath0 gravity both in the jordan frame and the einstein frame . in the jordan frame
, we present the general analytic expression for @xmath0 models that have the same expansion history as the @xmath1cdm model .
this analytic form can provide further insights on how cosmology can be used to test the @xmath0 gravity at the largest scales .
moreover we present a systematic and self - consistent way to construct the viable @xmath0 model in jordan frame using the mass dilation rate function from the einstein frame through the conformal transformation .
in addition , we extend our study to the linear perturbation theories and we further exhibit the equivalence of the @xmath0 gravity presented in the jordan frame and einstein frame in the perturbed space - time .
we argue that this equivalence has solid physics root . .
And you have already written the first three sentences of the full article: there has been conclusive evidence indicating that our universe is experiencing an accelerated expansion .
this acceleration is believed driven by a so called dark energy ( de ) in the framework of einstein s general relativity .
the simplest explanation of such de is the cosmological constant ..
Please generate the next two sentences of the article | but it suffers serious problems such that its value is far below the prediction of any sensible quantum field theories and it inevitably sustains the coincidence problem with the mysterious same order energy density as the matter field today .
there exists an alternative way to explain the acceleration of the universe expansion by modifying the einstein s gravity . |
6,016 | Suppose that you have an abstract for a scientific paper: we propose a scheme for spin - squeezing in the orbital motion of a bose - einstein condensate ( bec ) in a toroidal trap .
a circular lattice couples two counter - rotating modes and squeezing is generated by the nonlinear interaction spatially modulated at half the lattice period . by varying the amplitude and phase of the modulation ,
various cases of the twisting tensor can be directly realized , leading to different squeezing regimes .
these include one - axis twisting and the two - axis counter - twisting which are often discussed as the most important paradigms for spin squeezing .
our scheme naturally realizes the lipkin - meshkov - glick model with the freedom to vary all its parameters simultaneously . .
And you have already written the first three sentences of the full article: squeezing in an ensemble of two - level systems @xcite is a quantum phenomenon with applications ranging from quantum information @xcite to precision metrology @xcite .
since the canonical two - level system is a spin-@xmath0 particle , this is often referred to as `` spin squeezing '' , but physical realizations include a broad range of systems defined by the same lie algebra , such as two - component becs @xcite or polarized light @xcite .
a seminal paper by kitagawa and ueda @xcite established nonlinear dynamics as a natural way to generate spin - squeezing , via two distinct mechanisms : by one - axis twisting ( oat ) on the bloch sphere with hamiltonian @xmath1 , and two - axis counter - twisting ( tact ) with hamiltonian @xmath2 , with @xmath3 being components of the collective spin operator ..
Please generate the next two sentences of the article | the latter scenario is more efficient in generating strong spin squeezing , however no experiment has achieved it directly , but schemes have been proposed to convert oat into effective tact hamiltonians @xcite .
the spin - squeezing hamiltonian quadratic in @xmath3 is part of the more general lipkin - meshkov - glick ( lmg ) model @xcite , an important exactly solvable model introduced to test various many - body approximation methods . |
6,017 | Suppose that you have an abstract for a scientific paper: we present evidence that the optically unidentified radio source , first j121839.7 + 295325 , may be strongly lensing a background galaxy .
we estimate the redshift of the assumed gravitational arc , discovered in parallel imaging with hst , from mmt - blue channel spectroscopy to be @xmath0 .
we present lens models with an einstein radius of @xmath1 which contains a mass of @xmath2 m@xmath3 , where the uncertainty reflects the range of possible lens redshifts .
the putative lens is not detected to @xmath4 mag and @xmath5 mag in our mmt - swirc imaging . using the flux limits from wfpc2 and swirc
, we estimate that the dynamical mass - to - light ratio of j121839.7 + 295325 is @xmath6 m@xmath3 l@xmath7 for @xmath8 mag , and this lower limit could be as high as @xmath9 m@xmath3 l@xmath7 for @xmath10 mag . since the radio source is optically unidentified ( @xmath11 mag ) and has a radio flux of @xmath12 mjy , it is likely a massive early - type galaxy which hosts a radio - loud agn at @xmath13
. however , the present data can not uniquely determine the mass - to - light ratio of the lensing galaxy , and hence the possibility that this system may be a reasonably dark lens is not ruled out . .
And you have already written the first three sentences of the full article: in the @xmath14-dominated , cold dark matter ( @xmath14cdm ) cosmology , massive galaxies form hierarchically inside of dark matter haloes ( eg . * ? ? ? * ; * ? ? ? * ) .
the mass evolution of these cdm haloes can place stringent constraints on the cosmological models ( eg . * ? ? ?
* ) , and the most reliable measurements of cdm halo masses are generally derived from modeling gravitationally lensed images . furthermore , gravitational lensing has become a powerful tool for studying properties of both the lensing objects and the more distant sources ..
Please generate the next two sentences of the article | of particular interest are constraints on the mass profiles ( eg . * ? ? ?
* ; * ? ? ? |
6,018 | Suppose that you have an abstract for a scientific paper: this survey article describes a method for choosing uniformly at random from any finite set whose objects can be viewed as constituting a distributive lattice .
the method is based on ideas of the author and david wilson for using `` coupling from the past '' to remove initialization bias from monte carlo randomization .
the article describes several applications to specific kinds of combinatorial objects such as tilings , constrained lattice paths , and alternating - sign matrices .
_ this article is dedicated to herbert wilf + in honor of his sixty - fifth birthday . _ .
And you have already written the first three sentences of the full article: herb wilf , in addition to having done important work on problems related to counting combinatorial objects , has also done pioneering research on algorithms for generating combinatorial objects `` at random '' ( that is , generating an element of a finite combinatorial set so that each element has the same probability of being generated as any other ) ; see @xcite , @xcite , @xcite , @xcite , @xcite , @xcite , @xcite , @xcite , @xcite , @xcite and @xcite for fruits of this research .
this survey article describes a recent advance in the area of random generation , with applications to plane partitions , domino tilings , alternating sign matrices , and many other sorts of combinatorial objects .
the algorithm is of the `` random walk '' or `` monte carlo '' variety , but unlike many such algorithms it does not have any initialization bias ..
Please generate the next two sentences of the article | the heart of the algorithm is the method of coupling from the past explored by david wilson and myself in a joint article @xcite . for the sake of readability and motivation
, i will start by focusing on the application of our method to plane partitions . |
6,019 | Suppose that you have an abstract for a scientific paper: we present results of a search for a supernova ( sn ) component associated with grb 100418a at the redshift of 0.624 .
the field of grb 100418a was observed with focas on subaru 8.2 m telescope under a photometric condition ( seeing ) on 2010 may 14 ( ut ) .
the date corresponds to 25.6 days after the burst trigger ( 15.8 days in the restframe ) .
we did imaging observations in @xmath0 , and @xmath1 bands , and two hours of spectrophotometric observations .
we got the resolved host galaxy image which elongated (= 11 kpc ) from north to south .
no point source was detected on the host galaxy .
the time variation of @xmath2band magnitude shows that the afterglow of grb 100418a has faded to @xmath3 without sn like rebrightening , when we compare our measurement to the reports in gcn circulars .
we could not identify any sn feature such as broad emission - lines or bumps in our spectrum . assuming the sn is fainter than the @xmath4 noise spectrum of our observation
, we estimate the upper limit on the sn absolute magnitude @xmath5 in observer frame @xmath6band .
this magnitude is comparable to the faintest type ic sne .
we also estimate host galaxy properties from the spectrum .
the host galaxy of grb 100418a is relatively massive ( log @xmath7 ) compared to typical long grb host galaxies , and has 12+log(o / h ) = 8.75 . .
And you have already written the first three sentences of the full article: long gamma - ray bursts ( grbs ) are now considered to be death of massive stars ( so called collapsar scenario ) .
the most convincing observational evidences have been associations with supernovae ( sne ) .
some associations were spectroscopically , others were photometrically . however , there is at least one long grb , grb 060614 ( duration @xmath8 sec , @xcite ) whose sn component was not detectable to very deep limits ..
Please generate the next two sentences of the article | grb 060505 is also a @xmath9 sec burst without a detectable sn @xcite , although its duration @xmath10 4 sec is close to the classical 2 sec threshold which separates the long and short populations of grbs .
various progenitor models have been proposed to explain these events . |
6,020 | Suppose that you have an abstract for a scientific paper: a generalized trial wave function termed as the `` multi-@xmath0 ansatz '' has been developed to study the ground state of the spin - boson model with simultaneous diagonal and off - diagonal coupling in the sub - ohmic regime .
ground state properties including the energy and the spin polarization are investigated , and the results are consistent with those from the exact diagonalization and density matrix renormalization group approaches for the cases involving two oscillators and two baths described by a continuous spectral density function .
breakdown of the rotational and parity symmetries along the continuous quantum phase transition separating the localized phase from the critical phase has been uncovered .
moreover , the phase boundary is determined accurately with the corresponding symmetry parameters of the rotational and parity symmetries .
a critical value of the spectral exponent @xmath1 is predicted in the weak coupling limit , which is in agreement with the mean - field prediction of @xmath2 , but much smaller than the earlier literature estimate of @xmath3 . .
And you have already written the first three sentences of the full article: the paradigm of a quantum spin interacting with its dissipative environment has drawn sustained research interests in a variety of fields including quantum computation @xcite , spin dynamics @xcite , quantum phase transitions @xcite , charge transfer in biological molecules @xcite and impurity effects in magnetic materials @xcite . among the most popular models employed in this
regards is the spin - boson model @xcite that describes a two - level system , i.e. , a spin @xmath2 , coupled linearly to an environment represented by a set of harmonic oscillators .
the coupling between the system and the environment can be characterized by a spectral function @xmath4 ..
Please generate the next two sentences of the article | this model is known to exhibit rich ground state properties . in particular ,
if the bath is characterized by a gapless spectral density @xmath5 , a quantum phase transition is expected to appear , separating a non - degenerate `` delocalized '' phase from a doubly degenerate `` localized '' phase due to the competition between tunneling and environment - induced dissipation . depending on the value of @xmath6 , |
6,021 | Suppose that you have an abstract for a scientific paper: the @xmath0 heisenberg antiferromagnet is studied on the kagom lattice by using a green s function method based on an appropriate decoupling of the equations of motion .
thermodynamic properties as well as spin - spin correlation functions are obtained and characterize this system as a two - dimensional quantum spin liquid .
spin - spin correlation functions decay exponentially with distance down to low temperature and the calculated missing entropy at @xmath1 is found to be @xmath2 . within the present scheme ,
the specific heat exhibits a single peak structure and a @xmath3 dependence at low temperature . .
And you have already written the first three sentences of the full article: antiferromagnetic spin systems on fully frustrated lattices show many unusual behaviors in magnetic and thermal properties@xcite .
one of the main ingredients is that their unit cell allows for a continuous degree of freedom and that the connectivity ( corner sharing ) allows for an extensive number of these degrees of freedom in the classical ground state .
more subtle phenomena appear when looking at quantum models on these lattices as quantum fluctuations may induce very unsusual ground states . in particular , wether the quantum ground state on fully frustrated lattices may not break the lattice symmetry nor the spin group symmetry is still a highly debated question ..
Please generate the next two sentences of the article | a lot of work has been done to answer this question in the framework of the proposition of anderson@xcite , looking first at resonating valence bond states .
one of the most studied candidates is the quantum @xmath4=1/2 heisenberg antiferromagnet on the kagom lattice . using various methods@xcite |
6,022 | Suppose that you have an abstract for a scientific paper: we consider a class of point processes ( pp ) , which we call _ sub - poisson _ ; these are pp that can be directionally - convexly ( @xmath0 ) dominated by some poisson pp .
the @xmath0 order has already been shown in @xcite useful in comparing various point process characteristics , including ripley s and correlation functions as well as shot - noise fields generated by pp , indicating in particular that smaller in the @xmath0 order processes exhibit more regularity ( less clustering , less voids ) in the repartition of their points . using these results , in this paper we study the impact of the @xmath0 ordering of pp on the properties of two continuum percolation models , which have been proposed in the literature to address macroscopic connectivity properties of large wireless networks .
as the first main result of this paper , we extend the classical result on the existence of phase transition in the percolation of the gilbert s graph ( called also the boolean model ) , generated by a homogeneous poisson pp , to the class of homogeneous sub - poisson pp .
we also extend a recent result of the same nature for the sinr graph , to sub - poisson pp . finally , as examples we show that the so - called perturbed lattices are sub - poisson .
more generally , perturbed lattices provide some spectrum of models that ranges from periodic grids , usually considered in cellular network context , to poisson ad - hoc networks , and to various more clustered pp including some doubly stochastic poisson ones .
percolation , @xmath0 order , gilbert s graph , boolean model , sinr graph , wireless network , poisson point process , perturbed lattice , determinantal point process , connectivity , capacity .
And you have already written the first three sentences of the full article: a _ network _ , in the simplest terms , is a collection of points in some space ( e.g. on the euclidean plane ) , called _ nodes _ or _ vertexes _ , and a collection of node pairs , called _
edges_. the presence of an edge between two nodes indicates that they can directly communicate with each other .
the mathematical name for this network model is _.
Please generate the next two sentences of the article | graph_. a class of networks that has recently attracted particular interest in the wireless communication context , is called _ ad - hoc networks_. it is distinguished by the fact that the network nodes are not subject to any regular ( say periodic ) geometric emplacement in the space but can be rather seen as a snapshot of some _ random point pattern _ , called also _ point process _ ( pp ) in the mathematical formalism typically used in this context .
connectivity , i.e. possibility of indirect , multi - hop , communication between distant nodes , is probably the first issue that has to be addressed when considering ad - hoc networks . |
6,023 | Suppose that you have an abstract for a scientific paper: let @xmath0 be i.i.d .
nonnegative random variables with bounded density , mean @xmath1 , and finite positive variance @xmath2 .
let @xmath3 be the @xmath4 random markov matrix with i.i.d .
rows defined by @xmath5 . in particular , when @xmath6 follows an exponential law , the random matrix @xmath3 belongs to the dirichlet markov ensemble of random stochastic matrices .
let @xmath7 be the eigenvalues of @xmath8 i.e. the roots in @xmath9 of its characteristic polynomial .
our main result states that with probability one , the counting probability measure @xmath10 converges weakly as @xmath11 to the uniform law on the disk @xmath12 .
the bounded density assumption is purely technical and comes from the way we control the operator norm of the resolvent . .
And you have already written the first three sentences of the full article: the _ eigenvalues _ of an @xmath4 complex matrix @xmath13 are the roots in @xmath9 of its characteristic polynomial .
we label them @xmath14 so that @xmath15 with growing phases
spectral radius _ is @xmath16 ..
Please generate the next two sentences of the article | we also denote by @xmath17 the _ singular values _ of @xmath13 , defined for all @xmath18 by @xmath19 where @xmath20 is the conjugate - transpose .
the matrix @xmath13 maps the unit sphere to an ellipsoid , the half - lengths of its principal axes being the singular values of @xmath13 . |
6,024 | Suppose that you have an abstract for a scientific paper: we theoretically investigate the robustness of cluster states in charge qubit system based on quantum dot ( qd ) and double quantum point contact ( dqpc ) .
trap state is modeled by an island structure in dqpc and represents a dynamical fluctuation .
we found that the dynamical fluctuations affect the cluster states more than static fluctuation caused by qd size fluctuation . .
And you have already written the first three sentences of the full article: one - way quantum computing @xcite is an important approach for quantum computation based on a series of one - qubit measurements starting from a cluster state of a qubit array .
cluster states are highly - entangled states involving all qubits and are typically generated from an ising - like hamiltonian , starting from an initial product state @xmath0 , where @xmath1 . here ,
@xmath2 and @xmath3 are the two states of the @xmath4-th qubit in an @xmath5-qubit system . in ref ..
Please generate the next two sentences of the article | @xcite , we showed that cluster states in charge qubits@xcite can be created by applying a single gate bias pulse , right after preparing the initial product state ( one - step generation method ) , and are more robust against nonuniformities among qubits than decoherence - free ( df ) states @xcite under a noise environment generated by a quantum point contact ( qpc ) detector , which is a sensitive detector of electric charge distribution@xcite .
however , trap sites are often unavoidable in solid - state qubits owing to their small fabrication size and several experiments show that trap states significantly affect electric transport properties of nanoscale devices@xcite . here , we model the trap site as the island ( discrete energy state ) between double qpcs ( dqpc ) and investigate robustness of cluster states in charge qubits measured by the dqpc detector ( fig . |
6,025 | Suppose that you have an abstract for a scientific paper: we discuss the application of the regularization independent ( ri ) scheme of rome / southampton to determine the normalization of heavy quark operators non - perturbatively using the fermilab action . .
And you have already written the first three sentences of the full article: heavy meson hadronic matrix elements play an essential role in determining many of the parameters of the standard model , such as the ckm matrix elements .
theoretically , lattice gauge theory provides a means of computing these hadronic matrix elements with better control of systematic errors @xcite .
the heavy quark methods that have been successfully used on the lattice are : sheikholeslami - wohlert ( sw ) action , nonrelativistic qcd , heavy quark effective theory ( hqet ) and fermilab action . here.
Please generate the next two sentences of the article | we focus on the fermilab action because it may best control the systematic errors associated with the large quark mass .
renormalization of lattice operators is necessary in order to obtain physical results from numerical simulations . |
6,026 | Suppose that you have an abstract for a scientific paper: we provide a concise overview on transverse momentum dependent ( tmd ) parton distribution functions , their application to topical issues in high - energy physics phenomenology , and their theoretical connections with qcd resummation , evolution and factorization theorems .
we illustrate the use of tmds via examples of multi - scale problems in hadronic collisions .
these include transverse momentum @xmath0 spectra of higgs and vector bosons for low @xmath0 , and azimuthal correlations in the production of multiple jets associated with heavy bosons at large jet masses .
we discuss computational tools for tmds , and present an application of a new tool , , to parton density fits and parameterizations .
desy 15 - 111 + nikhef 2015 - 023 + ral - p-2015 - 006 .
And you have already written the first three sentences of the full article: experimental information on 3-dimensional imaging " of hadrons , encoded in unintegrated , transverse momentum dependent ( tmd ) parton density and parton decay functions , comes at present from two main sets of experimental data : deep inelastic scattering ( dis ) at high energy , and low-@xmath0 drell - yan ( dy ) and semi - inclusive dis ( polarized and unpolarized ) . in each of these two cases ,
qcd factorization theorems allow one to relate physical , observable cross sections to tmd parton distributions via perturbatively calculable kernels .
these theorems provide the theoretical basis for determining tmd distributions from experimental measurements ..
Please generate the next two sentences of the article | they are also essential to formulate and apply methods of perturbative resummation at all orders in the qcd coupling to a large variety of observables in high - energy hadronic collisions .
examples include processes both at the large hadron collider ( lhc ) and at fixed - target experiments . |
6,027 | Suppose that you have an abstract for a scientific paper: we derive the bethe - salpeter ( bs ) equations for the collective - mode spectrum of superfluid fermi gases of equal mixture of atomic fermi gas of two hyperfine states loaded into a moving optical lattice . in a moving lattice
the superfluid state is unstable due to spontaneous emission of the short - wavelength rotonlike excitations which appear in the spectrum of the collective modes .
it is shown that the spectrum obtained by the bs equations is in an excellent agreement with the collective - mode dispersion calculated by the perturbation approach , while there are some differences between the results obtained by density response function method and by the bs approach .
the difference increases with increasing the lattice velocity , which can be seen in the analytical approximations for the dispersion relation in the long - wavelength limit in a weak - coupling regime . .
And you have already written the first three sentences of the full article: the experimental ability to create a superfluid alkali atom fermi gas in optical lattices@xcite opens a new opportunity to study strongly correlated quantum many - particle systems and to emulate high - temperature superconductors .
theoretical description of ultracold atomic bose and fermi gases in optical lattices has attracted much attention.@xcite near the feshbach resonance the atom - atom interaction can be manipulated in a controllable way because the scattering length @xmath0 can be changed from the bcs side ( negative values ) to the bec side ( positive values ) reaching very large values close to resonance . on bec side of the resonance the spin - up and spin - down atoms can form diatomic molecules , and these bosonic molecules can undergo a bec at low enough temperature.@xcite in what follow we focus our attention on the bcs side ( negative scattering length ) where bcs superfluidity is expected analogous to superconductivity . in particular , we consider an equal mixture of atomic fermi gas of two hyperfine states with contact interaction loaded into an optical lattice .
the two hyperfine states are described by pseudospins @xmath1 ..
Please generate the next two sentences of the article | we also assume that the number of atoms in each hyperfine state per site ( the filling factor ) is smaller than unity , and that the lattice potential is sufficiently deep such that the tight - binding approximation is valid .
the system in this case is well described by the single - band attractive hubbard model : @xmath2 here , the fermi operator @xmath3 ( @xmath4 ) creates ( destroys ) a fermion on the lattice site @xmath5 with pseudospin @xmath1 and @xmath6 is the density operator on site @xmath5 with a position vector @xmath7 . |
6,028 | Suppose that you have an abstract for a scientific paper: we describe left - invariant half - flat @xmath0-structures on @xmath1 using the representation theory of @xmath2 and matrix algebra .
this leads to a systematic study of the associated cohomogeneity one ricci - flat metrics with holonomy @xmath3 obtained on @xmath4-manifolds with equidistant @xmath5 hypersurfaces .
the generic case is analysed numerically .
* half - flat structures on * thomas bruun madsen and simon salamon _ keywords : _ @xmath3- and @xmath0-structures , einstein and ricci - flat manifolds , special and exceptional holonomy , stable forms , superpotential . _
2010 mathematics subject classification : _
primary 53c25 , 53c29 ; secondary 53c44 , 53d20 , 83e15 , 83e30 . .
And you have already written the first three sentences of the full article: it was calabi @xcite who first recognised the rich geometry that can be found on a hypersurface of @xmath6 when the latter is equipped with its natural cross product and @xmath3-structure .
the realization , much later , of metrics with holonomy _ equal _ to @xmath3 allowed this theory to be extended , whilst retaining the key features of the `` euclidean '' theory . the second fundamental form or weingarten map @xmath7 of a hypersurface @xmath8 in a manifold @xmath9 with holonomy @xmath3 can be identified with the intrinsic torsion of the associated @xmath0-structure .
the latter is defined by a 2-form @xmath10 and a @xmath11-form @xmath12 induced on @xmath8 , and @xmath7 is determined by their exterior derivatives ..
Please generate the next two sentences of the article | the symmetry of @xmath7 translates into a constraint on the intrinsic torsion ( equivalently , on @xmath13 and @xmath14 ) that renders the @xmath0-structure what is called _
half flat_. conversely , a @xmath15-manifold @xmath8 with an @xmath0-structure that is half flat can ( at least if it is real analytic ) be embedded in a manifold with holonomy @xmath3 @xcite . |
6,029 | Suppose that you have an abstract for a scientific paper: we propose a method to determine the singlet - pair energy of a spin-2 bose - einstein condensate ( bec ) . by preparing the initial populations in the magnetic sublevels @xmath0 and @xmath1 with appropriate relative phases , we can obtain the coefficient of the spin singlet - pair term from the spin exchange dynamics .
this method is suitable for hyperfine states with short lifetimes , since only the initial change in the population of each magnetic sublevel is needed .
this method therefore enables the determination of the ground state phase of a spin-2 @xmath2 bec at zero magnetic field , which is considered to lie in the immediate vicinity of the boundary between the antiferromagnetic and cyclic phases .
we also show that the initial state in which relative phases are controlled can be prepared by raman processes . .
And you have already written the first three sentences of the full article: a bose - einstein condensate ( bec ) in an optical trap @xcite exhibits a rich variety of spin - related phenomena , such as various magnetic phases @xcite and spin domain formation @xcite .
the nuclear spin of @xmath2 and @xmath3 is @xmath4 , and combined with the spin @xmath5 of the outermost electron , the possible hyperfine spins of these atomic species are @xmath6 and @xmath7 .
the @xmath6 bec was first realized at mit with @xmath8 @xcite , for which the antiferromagnetic behavior was observed @xcite . on the other hand , @xmath2 in the @xmath6 hyperfine state was found to be ferromagnetic @xcite ..
Please generate the next two sentences of the article | the @xmath7 @xmath3 condensate was also realized by the mit group @xcite , whose ground state phase at zero magnetic field is predicted to be antiferromagnetic @xcite .
however , the ground state phase and the spin dynamics of the @xmath7 @xmath3 bec have not been studied because of its very short lifetime ( a few milliseconds ) , due to the fact that the energy of the @xmath9 state is higher than that of the @xmath6 state . |
6,030 | Suppose that you have an abstract for a scientific paper: the intense beam - beam effect at the interaction point of the international linear collider ( ilc ) causes large disruption of the beams and the production of photons .
these photons , arising dominantly through beamstrahlung emission , are problematic for the machine design as they need to be transported and dumped in a controlled way . in this work ,
we perform simulations of the beam - beam interaction to predict photon production rates and distributions for the different beam parameters considered at ilc .
the results are expressed in terms of a set of cones of excluded power , allowing to define the beam - stay - clear requirements relevant for different cases and contexts .
a comparison is also made with theoretical expectations .
the suggested photon cone half - opening angles are 0.75 and 0.85 mrad in the horizontal and vertical planes , respectively .
these cones cover all machine energies and parameter sets , and include the low power compton photons . .
And you have already written the first three sentences of the full article: the international linear collider ( ilc ) @xcite is an electron - positron collider with a centre - of - mass energy up to 1 tev and a luminosity goal of @xmath0 .
the achievement of this goal is challenging , and requires nanometre - sized colliding beams at the interaction point , achieved through emittance reductions in dedicated damping rings and strong focusing before the interaction point .
this , combined with the high bunch charge leads to intense electromagnetic interactions when the beams collide , causing particles of each bunch to be deflected by the space charge of the other ..
Please generate the next two sentences of the article | such deflections strongly enhance the angular divergence of the outgoing beams and significantly dilute their energy distributions , through radiation of so - called beamstrahlung photons .
re - interactions involving these photons also produce additional secondary charged particles . |
6,031 | Suppose that you have an abstract for a scientific paper: we report a measurement of the rossiter
mclaughlin effect in the transiting extrasolar planetary system tres-1 , via simultaneous spectroscopic and photometric observations with the subaru and magnum telescopes . by modeling the radial velocity anomaly that was observed during a transit ,
we determine the sky - projected angle between the stellar spin axis and the planetary orbital axis to be @xmath0 [ deg ] .
this is the third case for which @xmath1 has been measured in a transiting exoplanetary system , and the first demonstration that such measurements are possible for relatively faint host stars ( @xmath2 , as compared to @xmath3 for the other systems ) .
we also derive a time of mid - transit , constraints on the eccentricity of the tres-1b orbit ( @xmath4 ) , and upper limits on the mass of the trojan companions ( @xmath514 @xmath6 ) at the 3@xmath7 level . .
And you have already written the first three sentences of the full article: the rossiter mclaughlin effect ( hereafter the rm effect ) is a phenomenon originally reported as a `` rotational effect '' in eclipsing binary systems by @xcite ( for the beta lyrae system ) and @xcite ( for the algol system ) . in the context of extrasolar planetary science ,
the rm effect is seen as a radial velocity anomaly during a planetary transit caused by the partial occultation of the rotating stellar disk ( see @xcite , @xcite , or @xcite , for theoretical descriptions ) .
the radial velocity anomaly depends on the trajectory of the planet across the disk of the host star , and in particular on the alignment between that trajectory and the rotation field of the star . by monitoring this anomaly throughout a transit.
Please generate the next two sentences of the article | one can determine whether or not the planetary orbital axis is well - aligned with the stellar spin axis .
in the solar system , the orbits of all 8 planets are known to be well - aligned with the solar equator , but this is not necessarily the case for exoplanetary systems , or for hot jupiters in particular . |
6,032 | Suppose that you have an abstract for a scientific paper: core - collapse supernovae are among the prime candidate sources of high energy neutrinos . accordingly , the icecube collaboration has started a program to search for such a signal .
icecube operates an online search for neutrino bursts , forwarding the directions of candidate events to a network of optical telescopes for immediate follow - up observations . if a supernova is identified from the optical observations , in addition to a directional coincidence a temporal @xmath0-@xmath1 coincidence also needs to be established . to achieve this ,
we present a method for estimating the supernova explosion time from its light curve using a simple model .
we test the model with supernova light curve data from sn1987a , sn2006aj and sn2008d and show that the explosion times can be determined with an accuracy of better than a few hours . .
And you have already written the first three sentences of the full article: supernova explosions feature the interplay of all four known fundamental forces . a complete picture of supernova ( sn ) explosions will therefore require true multi - messenger observations , with data from traditional optical telescopes analyzed alongside coincident data from neutrino and gravitational wave detectors . to provide such multi - messenger data as well as to increase the sensitivity to neutrinos from sne , the icecube collaboration @xcite together with the rotse collaboration @xcite have set up an optical follow - up program that triggers optical observations on multiplets of high - energy muon neutrinos @xcite ( a similar program has been inplemented by the antares collaboration @xcite )
a multiplet is defined as at least two muon neutrinos from the same direction that arrive within a short time window ( e.g. , @xmath2 s ) .
when this happens , an alert is issued to the four rotse - iii telescopes , which immediately observe the corresponding region in the sky ..
Please generate the next two sentences of the article | successful @xmath0-@xmath1 coincident detection would allow one to infer the existence of jets in sne and would probe the expected gamma - ray burst supernova connection @xcite .
absent any other corroborating astrophysical evidence , a standalone neutrino doublet is not a physically interesting occurrence because the background rate of such doublets from atmospheric muon neutrinos in icecube is @xmath3(10/yr ) . |
6,033 | Suppose that you have an abstract for a scientific paper: it is widely accepted that topological quantities are useful to describe quantum liquids in low dimensions .
the ( spin ) hall conductances are typical examples .
they are expressed by the chern numbers , which are topological invariants given by the berry connections of the ground states .
we present a topological description for the ( spin ) hall conductances on a discretized brillouin zone . at the same time
, it is quite efficient in practical numerical calculations for concrete models .
we demonstrate its validity in a model with quantum phase transitions .
topological changes supplemented with the transition is also described in the present lattice formulation . , and chern number , berry connection , hall conductance , lattice gauge theory .
And you have already written the first three sentences of the full article: -0.3 cm topological quantities are fundamental to describe low dimensional quantum liquids where standard symmetry breaking do not have a primal importance @xcite .
typical examples are quantum hall liquids @xcite and anisotropic superconductors with time - reversal symmetry breaking @xcite .
recently spin hall conductance for semiconductors are also attracting much current interest @xcite ..
Please generate the next two sentences of the article | the ( spin ) hall conductance has a characteristic geometrical meaning @xcite . in some physical units , they are given by the first chern number of the berry connection @xcite . in practical numerical calculations , we diagonalize hamiltonians on a set of discrete points on the brillouin zone ( bz ) .
it is thus crucial to develop an efficient method of revealing the topological property of infinite systems with continuum bz from corresponding finite systems with discrete bz . |
6,034 | Suppose that you have an abstract for a scientific paper: in this presentation , we report our recent studies on the @xmath0 photoproduction off the proton target , using the tree - level born approximation , via the effective lagrangian approach . in addition , we include the nine ( three- or four - star confirmed ) nucleon resonances below the threshold @xmath1 mev , to interpret the discrepancy between the experiment and previous theoretical studies , in the vicinity of the threshold region . from the numerical studies , we observe that the @xmath2 and @xmath3 play an important role for the cross - section enhancement near the @xmath4
. it also turns out that , in order to reproduce the data , we have the vector coupling constants @xmath5 and @xmath6 . .
And you have already written the first three sentences of the full article: the strangeness meson photoproduction off the nucleon target is one of the most well - studied experimental and theoretical subjects to reveal the hadron production mechanisms and its internal structures , in terms of the strange degrees of freedom , breaking the flavor su(3 ) symmetry explicitly .
together with the recent high - energy photon beam developments in the experimental facilities , such as lpes2 at spring-8 and clas12 at jefferson laboratory @xcite , higher - mass strange meson - baryon photoproducitons must be an important subject to be addressed theoretically for future studies on those reaction processes . in the previous works @xcite ,
the @xmath0 photoproduction was investigated , the born approximation being used with the regge contributions . in comparison with the preliminary experimental data.
Please generate the next two sentences of the article | @xcite , the theory reproduced the data qualitatively well , but the theoretical cross - section strength was underestimated in the vicinity of the @xmath4 . in the present talk ,
we want to report our recent study to explain this discrepancy observed in the previous work . |
6,035 | Suppose that you have an abstract for a scientific paper: motivated by experiments on ion irradiated graphene , we compute the resistivity of graphene with dilute impurities . in the local moment regime we employ the perturbation theory up to third order in the exchange coupling to determine the behavior at high temperatures within the kondo model .
resistivity due to charge fluctuations is obtained within the mean field approach on the anderson impurity model . due to the linear spectrum of the graphene
the kondo behavior is shown to depend on the gate voltage applied .
the location of the impurity on the graphene sheet is an important variable determining its effect on the kondo scale and resitivity .
our results show that for chemical potential near the node the charge fluctuations is responsible for the observed temperature dependence of resistivity while away from the node the spin fluctuations take over .
quantitative agreement with experimental data is achieved if the energy of the impurity level varies linearly with the chemical potential . .
And you have already written the first three sentences of the full article: a logarithmic upturn in the resistivity at low temperature has been observed in graphene with vacancies@xcite .
a fit to the temperature dependence of resistivity with conventional kondo effect yields a large kondo temperature ( with @xmath0 ) which shows a non - monotonic behavior with respect to the gate voltage@xcite .
the vacancies in the graphene sheets are induced by ion irradiation in ultra - high vacuum and the magnetism in sputtered graphite has been experimentally observed@xcite . our goal is to study whether kondo effect alone in graphene can explain the experimental results in ref ...
Please generate the next two sentences of the article | we start with the anderson impurity model@xcite to study the impurities effect on transport . in the local moment regime
where the impurity occupation for a given spin @xmath1 we use schrieffer wolff transformation@xcite to write down the kondo model from the anderson impurity hamiltonian . |
6,036 | Suppose that you have an abstract for a scientific paper: we show how to convert a quantum stabilizer code to a one - way or two - way entanglement distillation protocol .
the proposed conversion method is a generalization of those of shor - preskill and nielsen - chuang .
the recurrence protocol and the quantum privacy amplification protocol are equivalent to the protocols converted from @xmath0 $ ] stabilizer codes .
we also give an example of a two - way protocol converted from a stabilizer better than the recurrence protocol and the quantum privacy amplification protocol .
the distillable entanglement by the class of one - way protocols converted from stabilizer codes for a certain class of states is equal to or greater than the achievable rate of stabilizer codes over the channel corresponding to the distilled state , and they can distill asymptotically more entanglement from a very noisy werner state than the hashing protocol . .
And you have already written the first three sentences of the full article: in many applications of quantum mechanics to communication , the sender and the receiver have to share a maximally entangled quantum state of two particles .
when there is a noiseless quantum communication channel , the sender can send one of two particles in a maximally entangled state to the receiver and sharing of it is easily accomplished .
however , the quantum communication channel is usually noisy , that is , the quantum state of the received particle changes probabilistically from the original state of a particle ..
Please generate the next two sentences of the article | entanglement distillation protocols @xcite and quantum error - correcting codes @xcite are the schemes for sharing a maximally entangled state over a noisy communication channel .
a distillation protocol is said to be _ two - way _ ( resp . |
6,037 | Suppose that you have an abstract for a scientific paper: results are presented of an analysis of proton and charged pion azimuthal distributions measured with respect to the reaction plane in au + au collisions at a beam momentum of about 11@xmath0 gev / c .
the azimuthal anisotropy is studied as a function of particle rapidity and transverse momentum for different centralities of the collisions .
the triple differential ( in rapidity , transverse momentum , and azimuthal angle ) distributions are reconstructed .
a comparison of the results with a previous analysis of charged particle and transverse energy flow as well as with model predictions are presented . .
And you have already written the first three sentences of the full article: collective phenomena play an important role in heavy - ion collisions , but for a long time it was assumed that , at collision energies much greater than 1 gev / nucleon , only longitudinal and azimuthally symmetric transverse radial flow would survive . during the last few years
the situation has changed qualitatively .
anisotropic , directed as well as elliptic , flow has been observed at the bnl ags @xcite , and strong indications of elliptic flow at the cern sps @xcite have been demonstrated ..
Please generate the next two sentences of the article | the theoretical understanding of the effect and model calculations involving anisotropic flow have progressed significantly ; different anisotropic flow patterns have been linked to such phenomena as quark - gluon plasma formation , softening of the equation of state @xcite , and mean - field effects during the fireball evolution @xcite .
the appropriate tools for flow studies at high energies have been developed @xcite . |
6,038 | Suppose that you have an abstract for a scientific paper: radiative corrections to neutrino mixings in seesaw models depend on the nature of new physics between the weak and the gut - seesaw scales and can be taken into account using the renormalization group equations .
this new physics effect becomes particularly important for models with quasi - degenerate neutrino masses where small neutrino mixings at the seesaw scale can get magnified by radiative renormalization effects alone to match observations .
this mechanism of radiative magnification which provides a simple understanding of why lepton mixings are so different from quark mixings was demonstrated by us for the standard supersymmetry scenario where the particle spectrum becomes supersymmetric above the weak scale . in this paper
, we examine this phenomenon in split supersymmetry scenarios and find that the mechanism works also for this scenario provided the susy scale is at least 2 - 3 orders below the gut - seesaw scale and one has larger values of @xmath0 . .
And you have already written the first three sentences of the full article: an important question in particle physics is the nature of new physics beyond the astoundingly successful standard model .
one compelling scenario for this new physics is the weak scale supersymmetry which provides an answer to a number of puzzles of the standard model such as a solution to the gauge hierarchy problem , the origin of electroweak symmetry breaking as well as providing a candidate for dark matter of the universe .
an added virtue is that it unifies the disparate strengths of the weak , electromagnetic and strong forces at a scale of about @xmath1 gev , opening up another rich landscape of new physics around this scale ..
Please generate the next two sentences of the article | this high scale new physics can only manifest itself at low energies via large radiative correction effects which depend logarithmically on mass as well as through effects such as proton decay which are suppressed by this new high scale .
there is reason to believe that there might be a manifestation of this new physics effect in the domain of neutrinos . |
6,039 | Suppose that you have an abstract for a scientific paper: we show that smoothing of multiaffine surfaces that are generated by simulating a crosslinked polymer gel by a frustrated , triangular network of springs of random equilibrium lengths [ g.m .
buenda , s.j .
mitchell , p.a .
rikvold , phys .
rev .
e 66 ( 2002 ) 046119 ] changes the scaling behavior of the surfaces such that they become self - affine .
the self - affine behavior is consistent with recent atomic force microscopy ( afm ) studies of the surface structure of crosslinked polymer gels into which voids are introduced through templating by surfactant micelles [ m. chakrapani , s.j .
mitchell , d.h .
van winkle , p.a .
rikvold , j. colloid interface sci .
, in press ] .
the smoothing process mimics the effect of the afm tip that tends to flatten the soft gel surfaces .
both the experimental and the simulated surfaces have a non - trivial scaling behavior on small length scales , with a crossover to scale - independent behavior on large scales .
_ pacs : _
61.43.hv ; 89.75.da ; 82.70.gg ; 68.37.ps _ keywords : _ self - affine scaling ; multiaffine scaling ; hydrogels ; atomic force microscopy .
And you have already written the first three sentences of the full article: in a recent study @xcite we proposed a frustrated spring - network model to simulate the surface structures of crosslinked polymer gels into which voids are introduced through templating by surfactant micelles . experimentally , templated polyacrylamide gels are created by mixing acrylamide with a crosslinker in the presence of a surfactant @xcite .
the resultant gels have a wide range of pore sizes , making them ideal materials for macromolecular separation @xcite .
the crosslinking process introduces inhomogeneities in the spatial density of the gel that affect its surface configuration ..
Please generate the next two sentences of the article | our results show that the surfaces generated by the spring - network model have a nontrivial , multiaffine scaling behavior at small length scales , with a crossover to scale - independent behavior on large scales . at small length scales we found that the @xmath0th order increment correlation function has a power - law behavior , with @xmath0-dependent exponents that change with the vacancy concentration .
however , experimental surfaces of surfactant - templated hydrogels studied by atomic force microscopy ( afm ) @xcite show @xmath0-independent self - affine scaling at length scales below the crossover length . in ref . |
6,040 | Suppose that you have an abstract for a scientific paper: we prove that @xmath0-dissimilarity vectors of weighted trees are points on the tropical grassmannian , as conjecture by cools in response to a question of sturmfels and pachter .
we accomplish this by relating @xmath0-dissimilarity vectors to the representation theory of @xmath1 .
And you have already written the first three sentences of the full article: we will explore tropical properties of weighted , or metric trees @xmath2 using the representation theory of the special linear group @xmath1 we direct the reader to the book by fulton and harris @xcite and the book by dolgachev @xcite for an introduction to the representation theory of connected complex reductive groups over @xmath3 . recall that we can choose a borel subgroup @xmath4 , and a maximal torus @xmath5 with @xmath6 and associate to this data a monoid of weights @xmath7 in the characters of @xmath8 which classify irreducible representations of @xmath9 up to isomorphism .
this cone comes with an involution defined by the duality operation on representations @xmath10 the direct sum of all such representations forms a commutative algebra @xmath11 which is the coordinate ring of the quotient of @xmath9 by the unipotent radical of a chosen borel subgroup , @xmath12.$ ] for @xmath13 , this can be taken to be the subgroup of unipotent upper - triangular matrices .
choosing a borel subgroup also fixes a set of positive roots @xmath14 for @xmath15 which define a partial ordering on the weights , we say that @xmath16 if @xmath17 is a member of @xmath18 for @xmath19 the cone @xmath20 is generated over @xmath21 by @xmath22 fundamental weights , @xmath23 the weight @xmath24 is the so - called highest weight of the representation @xmath25 the main result of this paper expresses the @xmath0-dissimilarity vector of an arbitrary tree in terms of the fundamental weights of @xmath13 . in what follows @xmath26 denotes the non - negative members of @xmath27 or @xmath28 let @xmath29 be a trivalent tree with @xmath30 ordered leaves , and let @xmath31 be a function which assigns a weight ( or length ) to each edge of @xmath32 the weight function @xmath33 defines a metric on the leaves @xmath34 of @xmath2 where the distance @xmath35 between the leaves @xmath36 and @xmath37 is the sum of the weights on the edges of the unique path @xmath38 connecting @xmath36 to @xmath37 in @xmath32 we intentionally confuse the....
Please generate the next two sentences of the article | @xmath40 obviously @xmath41 and @xmath42 we call the vector @xmath43 the @xmath44-dissimilarity vector of @xmath45 we may generalize this construction by introducing the convex hull of @xmath0 leaves @xmath46 as the set of all edges which appear in paths connecting some @xmath47 to some @xmath48 @xmath49 the @xmath0-dissimilarity vector @xmath50 is then defined as expected .
@xmath51 the set of @xmath44-dissimilarity vectors of weighted trees @xmath52 is well understood . |
6,041 | Suppose that you have an abstract for a scientific paper: when magnetic energy density is much larger than that of matter , as in pulsar / black hole magnetospheres , the medium becomes force - free and we need relativity to describe it . as in non -
relativistic magnetohydrodynamics ( mhd ) , alfvnic mhd turbulence in the relativistic limit can be described by interactions of counter - traveling wave packets . in this paper
we numerically study strong imbalanced mhd turbulence in such environments . here
, imbalanced turbulence means the waves traveling in one direction ( dominant waves ) have higher amplitudes than the opposite - traveling waves ( sub - dominant waves ) .
we find that ( 1 ) spectrum of the dominant waves is steeper than that of sub - dominant waves , ( 2 ) the anisotropy of the dominant waves is weaker than that of sub - dominant waves , and ( 3 ) the dependence of the ratio of magnetic energy densities of dominant and sub - dominant waves on the ratio of energy injection rates is steeper than quadratic ( i.e. , @xmath0 with @xmath1 ) .
these results are consistent with those obtained for imbalanced non - relativistic alfvnic turbulence .
this corresponds well to the earlier reported similarity of the relativistic and non - relativistic balanced magnetic turbulence . .
And you have already written the first three sentences of the full article: alfvn waves play important roles in strongly magnetized media .
they propagate along magnetic field lines with the alfvn speed @xmath2 , where @xmath3 is the strength of the mean magnetic field and @xmath4 is density .
alfvn waves moving in opposite directions can interact and result in alfvnic magnetohydrodynamic ( mhd ) turbulence ..
Please generate the next two sentences of the article | alfvnic mhd turbulence in the non - relativistic limit has been studied for many decades and the best available mhd turbulence model is , in spite of all existing controversies ( see * ? ? ?
* ; * ? ? ? |
6,042 | Suppose that you have an abstract for a scientific paper: the decay @xmath0 is studied using in - flight decays detected with the `` istra+ '' spectrometer .
about 920k events are collected for the analysis .
the @xmath1 slope parameter of the decay form - factor @xmath2 in the linear approximation ( average slope ) is measured : @xmath3(stat ) @xmath4(syst ) . the quadratic contribution to the form - factor
was estimated to be @xmath5(stat ) @xmath6(syst ) .
the linear slope , which has a meaning of @xmath7 for this fit , is @xmath8(stat ) @xmath4(syst ) .
the limits on possible tensor and scalar couplings are derived : @xmath9(stat ) @xmath10(syst ) , @xmath11(stat ) @xmath12(syst ) . by -by -21.9
cm -10pt 0.5 in 17.0 cm * high statistic measurement of the @xmath13 decay form - factors * + * o.p .
yushchenko , s.a .
akimenko , g.i .
britvich , k.v.datsko , a.p .
filin , a.v .
inyakin , a.s .
konstantinov , v.f .
konstantinov , i.y .
korolkov , v.a .
khmelnikov , v.m .
leontiev , v.p .
novikov , v.f .
obraztsov , v.a .
polyakov , v.i .
romanovsky , v.m .
ronjin , v.i .
shelikhov , n.e .
smirnov , o.g .
tchikilev , v.a.uvarov .
* 0.15 cm * @xmath14 * 0.35 cm * v.n .
bolotov , s.v .
laptev , a.yu . polyarush . * 0.15 cm * @xmath15 * .
And you have already written the first three sentences of the full article: the decay @xmath16 ( @xmath17 ) provides unique information about the dynamics of the strong interactions .
it has been a testing ground for such theories as current algebra , pcac , chiral perturbation theory(chpt ) .
the study of this decay has a particular interest in view of new two - loop order ( @xmath18 ) calculations for k@xmath19 decays in chpt @xcite ..
Please generate the next two sentences of the article | the high - order chpt calculations make a definite prediction for the quadratic term in the vector @xmath20 form - factor and link the scalar @xmath21 form - factor linear and quadratic slopes to the @xmath22 corrections . in turn
, @xmath22 is known to be crucial for the @xmath23 measurements . |
6,043 | Suppose that you have an abstract for a scientific paper: classical field theory is considered as a theory of unparametrized surfaces embedded in a configuration space , which accommodates , in a symmetric way , spacetime positions and field values .
dynamics is defined via the ( hamiltonian ) constraint between multivector - valued generalized momenta , and points in the configuration space .
starting from a variational principle , we derive the local equations of motion , that is , differential equations that determine classical surfaces and momenta .
a local hamilton - jacobi equation applicable in the field theory then follows readily .
in addition , we discuss the relation between symmetries and conservation laws , and derive a hamiltonian version of the noether theorem , where the noether currents are identified as the classical momentum contracted with the symmetry - generating vector fields .
the general formalism is illustrated by two examples : the scalar field theory , and the string theory . throughout the article
, we employ the mathematical formalism of geometric algebra and calculus , which allows us to perform completely coordinate - free manipulations . .
And you have already written the first three sentences of the full article: in non - relativistic mechanics , the trajectory of a particle is most commonly expressed as a function @xmath0 , which describes how the position of the particle evolves with time . in relativistic mechanics , where space and time are treated in a symmetric way
, the particle s trajectory is regarded as a sequence of spacetime events @xmath1 . in field theory , the field configuration is usually regarded as a function @xmath2 , which describes how the values of the fields vary from point to point in the spacetime
. however , the general relativity suggests @xcite that the spacetime is a dynamical entity , and as such , it should be put with the fields on the same footing ..
Please generate the next two sentences of the article | mathematically , instead of a function @xmath2 , one is therefore motivated to consider the respective graph , i.e. , the collection of points @xmath3 . in this article
, we develop the mathematical formalism for field theories proposed in ( * ? ? ? |
6,044 | Suppose that you have an abstract for a scientific paper: we present a distance measurement for the semiregular variable s crateris ( s crt ) based on its annual parallax . with the unique dual beam system of the vlbi exploration for radio astrometry ( vera ) telescopes ,
we measured the absolute proper motion of a water maser spot associated with s crt , referred to the quasar j1147@xmath00724 located at an angular separation of 1.23@xmath1 . in observations spanning nearly two years , we have detected the maser spot at the lsr velocity of 34.7kms@xmath2 , for which we measured the annual parallax of [email protected] corresponding to a distance of 430@xmath4pc .
this measurement has an accuracy one order of magnitude better than the parallax measurements of hipparcos .
the angular distribution and three - dimensional velocity field of maser spots indicate a bipolar outflow with the flow axis along northeast - southwest direction . using the distance and photospheric temperature
, we estimate the stellar radius of s crt and compare it with those of mira variables . .
And you have already written the first three sentences of the full article: very long baseline interferometry ( vlbi ) is a powerful technique for obtaining positions of celestial objects with milliarcsecond ( mas ) level accuracy .
the vlbi exploration of radio astrometry ( vera ) telescopes are a japanese vlbi array dedicated to phase referencing vlbi @xcite .
vera consists of four 20 m diameter antennas at mizusawa , ogasawara , iriki and ishigaki - jima ( see figure 1 of @xcite ) . to overcome phase fluctuations and the limited integration time in conventional fast - switching vlbi.
Please generate the next two sentences of the article | , vera has a dual beam system that allows simultaneous observations of the target and reference sources separated by 0.3 to 2.2 degrees .
this advanced capability of vera can be used to measure annual parallaxes and proper motions of masers with a 10 micro arcsecond ( @xmath5as ) level accuracy . |
6,045 | Suppose that you have an abstract for a scientific paper: in @xcite , paper i , we analyzed 15 years of spectroscopic and spectropolarimetric data from the ritter and pine bluff observatories of 2 be stars , 60 cygni and @xmath0 aquarii , when a transition from be to b star occurred .
here we anaylize the intrinsic polarization , where we observe loop - like structures caused by the rise and fall of the polarization balmer jump and continuum v - band polarization being mismatched temporaly with polarimetric outbursts .
we also see polarization angle deviations from the mean , reported in paper i , which may be indicative of warps in the disk , blobs injected at an inclined orbit , or spiral density waves .
we show our ongoing efforts to model time dependent behavior of the disk to constrain the phenomena , using 3d monte carlo radiative transfer codes . .
And you have already written the first three sentences of the full article: the time evolution of the intrinsic continuum v - band polarization ( v - pol ) of @xmath0 aqr is shown in figure 1 .
we find evidence of clockwise loop - like structures ( figure 2 ) when comparing the evolution of the polarization across the balmer jump ( bj ) vs v - pol , particularly during polarimetric outburst events ( red in figure 1 ) .
60 cyg also displays this behavior ..
Please generate the next two sentences of the article | we use the non - lte 3d monte carlo code developed by @xcite , hdust , to investigate the origin of the loop - like behavior of the bj vs v - pol during polarimetric outbursts .
interestingly , we find that the clockwise loop structures can be reproduced when the mass - loss from the central star which feeds the disk is turned on ( 6 to 12 o@xmath1clock , figure 3 ) then off ( 12 to 6 o@xmath1clock , figure 3 ) . |
6,046 | Suppose that you have an abstract for a scientific paper: motivated by recent proposals on strain - engineering of graphene electronic circuits we calculate conductivity , shot - noise and the density of states in periodically deformed graphene .
we provide the solution to the dirac - kronig - penney model , which describes the phase - coherent transport in clean monolayer samples with an one - dimensional modulation of the strain and the electrostatic potentials .
we compare the exact results to a qualitative band - structure analysis .
we find that periodic strains induce large pseudo - gaps and suppress charge transport in the direction of strain modulation .
the strain - induced minima in the gate - voltage dependence of the conductivity characterize the quality of graphene superstructures .
the effect is especially strong if the variation of inter - atomic distance exceeds the value @xmath0 , where @xmath1 is the lattice spacing of free graphene and @xmath2 is the period of the superlattice .
a similar effect induced by a periodic electrostatic potential is weakened due to klein tunnelling . .
And you have already written the first three sentences of the full article: graphene is recognized as the only two - dimensional crystal that withstands large deformations and high temperatures and is readily integrated into electronic circuits.@xcite the high electron mobility and unique spectral characteristics single out graphene as a promising key element for electronic and optoelectronic applications.@xcite the well - known dirac dispersion of electronic excitations in graphene is responsible for a number of interesting analogies with relativistic quantum electrodynamics,@xcite but prevents the use of graphene in field - effect transistors due to the absence of energy band - gaps.@xcite the strain - engineering of graphene circuits has been recently suggested as a means to bypass this difficulty.@xcite in the dirac - fermion picture of graphene , the strain gradient is equivalent to the presence of a pseudo - magnetic field , which can be manipulated to induce a zero - field quantum hall effect and a topological isolator state.@xcite the variation of strain may also induce substantial variation in the on - site electron energies , however , this effect is reduced by screening.@xcite the experimental realizations of strained graphene confirm its surprisingly high elasticity and pave the way for the development of strain - engineered graphene electronics.@xcite different techniques have been proposed to produce graphene samples with controlled periodical variations of strain.@xcite first transport measurements of graphene superstructures have been already reported.@xcite below we analyze the phase - coherent charge transport in periodically strained graphene samples and propose a way to characterize the quality of graphene superstructures on the basis of their transport properties .
more specifically we use the exact solution of the dirac - kronig - penney model to calculate density of states , conductance , and shot noise in transport through finite size graphene samples with periodic potentials . the scattering off the metal leads is taken into account in all quantities....
Please generate the next two sentences of the article | the angle @xmath4 specifies the orientation of the honeycomb lattice with respect to the transport direction @xmath5 . ]
this paper is organized as follows . in section [ sec : model ] the effective dirac hamiltonian for deformed graphene |
6,047 | Suppose that you have an abstract for a scientific paper: i briefly review the properties of the gas flow in and around the region of the bar in a disc galaxy and discuss the corresponding inflow and the loci of star formation .
i then review the flow of gas in barred galaxies which have an additional secondary bar .
finally i discuss the signatures of bars in edge - on galaxies .
# 1_#1 _ # 1#1 = # 1 1.25 in .125 in .25 in .
And you have already written the first three sentences of the full article: bars are elongated structures frequently present in the central parts of disc galaxies . their formation is ubiquitous in n - body simulations , unless a sufficiently massive and sufficiently centrally concentrated spherical or spheroidal component has been added to stop or at least to delay their formation beyond a reasonable life - time of the disc .
the problems relating to bar formation are far from being solved , but in this review i will leave them aside in order to concentrate on the properties of the gas flow in and around the bar region . such a flow is intimately linked to the main periodic orbits and their structure ( e.g. athanassoula 1992a ; athanassoula 1992b , hereafter a92b ) .
orbital calculations ( for a review see e.g. sellwood & wilkinson 1993 ) have shown that the backbones of bars are the so - called @xmath0 periodic orbits , which are elongated along the bar . if one or two inner lindblad resonances ( hereafter ilrs ) are present , there are also two perpendicular families , called @xmath1 and @xmath2 ..
Please generate the next two sentences of the article | further out we find the 4:1 periodic orbits , which have rectangular - like or diamond - like shapes .
these families , as well as other secondary ones , trap around them a number of regular orbits . |
6,048 | Suppose that you have an abstract for a scientific paper: magnetic fields play a crucial role in the physics of gamma - ray bursts ( grbs ) .
strong observational evidence indicates that the observed afterglow and most likely the prompt emission arise from synchrotron emission .
it is possible that poynting flux plays an important or even dominant role in the relativistic outflow from the inner engine , but like in other astronomical relativistic jets this suggestion is controversial .
finally , it is likely that magnetic fields larger than @xmath0 g occur within grbs inner engines and contribute to the acceleration and collimation of the relativistic jets .
i review here the grb fireball model and discuss the role that magnetic fields play in its various components .
i suggest that the early afterglow , that reflects the initial interaction of the relativistic jet with its surrounding matter is the best available tool to explore the nature of relativistic outflow in astronomical relativistic jets .
address = racah institute for physics , the hebrew university , jerusalem , 91904 israel + theoretical astrophysics , caltech , pasadena , ca 91125 , usa .
And you have already written the first three sentences of the full article: more than thirty years , after the discovery of gamma - ray bursts ( grbs ) we have now a reasonable grb model .
the model is based on the dissipation of an ultra - relativistic outflow . at first the flow
is dissipated by internal shocks ( or another form of internal dissipation ) that produce the prompt @xmath1-rays ..
Please generate the next two sentences of the article | later the interaction of the flow with the circum - burst matter produces an external shock and this blast wave produces the subsequent afterglow .
the role of magnetic fields varies within grb models from crucial to ultimate . |
6,049 | Suppose that you have an abstract for a scientific paper: helium ion microcopy ( him ) based on gas field ion sources ( gfis ) represents a new ultra high resolution microscopy and nano fabrication technique .
it is an enabling technology that not only provides imagery of conducting as well as uncoated insulating nano structures but also allows to create these features .
the latter can be achieved using resists or material removal due to sputtering .
the close to free form sculpting of structures over several length scales has been made possible by the extension of the method to other gases such as neon . a brief introduction of the underlying physics as well as a broad review of the applicability of the method is presented in this review . .
And you have already written the first three sentences of the full article: high resolution imaging , in particular in biology and materials science , is mostly done using scanning electron microscopy ( sem ) . the ease of use and the widespread availability has made this the number one method for imaging in the aforementioned fields . structuring and manipulation of nano
sized features is traditionally the domain of focused ion beams . here , mainly liquid metal ion sources ( lmis ) using gallium are used
however , other techniques such as various types of gfis,@xcite alloy lmis,@xcite magneto optical trap sources ( motis)@xcite and multicusp plasma sources@xcite are runners up.
Please generate the next two sentences of the article | . good reviews discussing these two techniques can be found in refs . [ ] and [ ] for sem and fib , respectively .
helium ion microscopy presents a technique that unites many of the advantages of sem and fib in a single tool . |
6,050 | Suppose that you have an abstract for a scientific paper: a highly concentrated ( 17 vol.% ) fe - c nano - particle system , with a narrow size distribution @xmath0 nm , has been investigated using magnetic ac susceptibility measurements covering a wide range of frequencies ( 17 mhz - 170 hz ) .
a dynamic scaling analysis gives evidence for a phase transition to a low temperature spin - glass - like phase .
the critical exponents associated with the transition are @xmath1 and @xmath2 .
the reason why the scaling analysis works for this sample , while it may not work for other samples exhibiting collective behavior as evidenced by aging phenomena , is that the single particle contribution to @xmath3 is vanishingly small for @xmath4 and hence all slow dynamics is due to collective behavior .
this criterion can only be fulfilled for a highly concentrated nano - particle sample with a narrow size distribution . .
And you have already written the first three sentences of the full article: dense nano - particle systems have been shown to exhibit collective behavior , as evidenced by aging , and non - equilibrium effects similar to spin glasses.@xcite whether that collective behavior is associated with a `` true '' spin glass phase transition is still controversial . in this paper , we show a dynamic scaling analysis to a spin glass transition for a highly concentrated fe - c nano - particle sample with a narrow particle size distribution .
we also discuss why the scaling analysis may not indicate a phase transition for samples with less interactions or wider size distributions . the sample consisted of ferromagnetic nanoparticles of amorphous @xmath5 ( [email protected] ) , with an average particle size of @xmath7 nm , prepared by the method described by van wonterghem et al . in ref .
the sample was studied in the frozen state and contained 17 vol% of particles ..
Please generate the next two sentences of the article | the ac - susceptibility measurements were performed in a non - commercial squid magnetometer for frequencies in the range @xmath8 17 mhz - 170 hz . fig . 1 shows @xmath9 and @xmath10 at different frequencies . a sample that exhibit a spin glass transition will show critical slowing down , and hence the characteristic relaxation time @xmath11 diverges at the transition temperature according to @xmath12 where @xmath13 is the transition temperature , @xmath14 is related to the relaxation time of the individual particle magnetic moments , and @xmath15 is a critical exponent .
we extracted the freezing temperature @xmath16 , associated with a relaxation time ( @xmath17 ) , from the out - of - phase component of the ac - susceptibility as @xmath18 with @xmath19 . |
6,051 | Suppose that you have an abstract for a scientific paper: let @xmath0 be a smooth minimal complex surface of general type with @xmath1 and @xmath2 .
we prove that any involution on @xmath0 is in the center of the automorphism group of @xmath0 . as an application
, we show that the automorphism group of an inoue surface with @xmath2 is isomorphic to @xmath3 or @xmath4 .
we construct a @xmath5-dimensional family of inoue surfaces with automorphism groups isomorphic to @xmath4 . .
And you have already written the first three sentences of the full article: the birational automorphism groups of projective varieties are extensively studied . nowadays we know that , for a projective variety of general type @xmath6 over an algebraically closed field of characteristic zero , the number of birational automorphisms of @xmath6 is bounded by @xmath7 , where @xmath8 is a constant which only depends on the dimension @xmath9 of @xmath6 , and @xmath10 is the volume of the canonical divisor @xmath11 ( cf .
furthermore , we know that @xmath12 and @xmath13 from the classical hurwitz theorem and xiao s theorem ( cf . @xcite and @xcite ) .
however , even in low dimensions , it is usually nontrivial to calculate the automorphism groups of explicit varieties of general type ( for example , see @xcite , @xcite , @xcite and @xcite ) ..
Please generate the next two sentences of the article | we focus on automorphisms of minimal smooth complex surfaces of general type with @xmath1 and @xmath2 .
involutions on such surfaces have been studied in @xcite and @xcite . |
6,052 | Suppose that you have an abstract for a scientific paper: in group activity selection problem ( ) , players form coalitions to participate in activities and have preferences over pairs of the form ( activity , group size ) . recently ,
igarashi et al .
@xcite have initiated the study of group activity selection problems on social networks ( ): a group of players can engage in the same activity if the members of the group form a connected subset of the underlying communication structure .
igarashi et al .
have primarily focused on nash stable outcomes , and showed that many associated algorithmic questions are computationally hard even for very simple networks . in this paper
we study the parameterized complexity of with respect to the number of activities as well as with respect to the number of players , for several solution concepts such as nash stability , individual stability and core stability .
the first parameter we consider in the number of activities . for this parameter
, we propose an fpt algorithm for nash stability for the case where the social network is acyclic and obtain a w[1]-hardness result for cliques ( i.e. , for classic ) ; similar results hold for individual stability .
in contrast , finding a core stable outcome is hard even if the number of activities is bounded by a small constant , both for classic and when the social network is a star .
another parameter we study is the number of players .
while all solution concepts we consider become polynomial - time computable when this parameter is bounded by a constant , we prove w[1]-hardness results for cliques ( i.e. , for classic ) . .
And you have already written the first three sentences of the full article: in mutliagent systems , agents form coalitions to perform tasks .
a useful model for analyzing how tasks can be allocated to groups of agents is the _ group activity selection problem _ ( ) , proposed by darmann et al .
@xcite . in s , participants express preferences over pairs of the form ( activity , group size ) ..
Please generate the next two sentences of the article | the activities are then assigned to participants so as to achieve the best performance for the whole system as well as to satisfy individual agents .
the key idea behind this formulation is that ideal group size depends on the task at hand : in a company , an ideal size of the sales team may differ from that of a web developers team . |
6,053 | Suppose that you have an abstract for a scientific paper: in this work we construct an effective four - dimensional model by compactifying a ten - dimensional theory of gravity coupled with a real scalar dilaton field on a time - dependent torus without the contributions of fluxes as first approximation .
this approach is applied to anisotropic cosmological bianchi type ii model for which we study the classical coupling of the anisotropic scale factors with the two real scalar moduli produced by the compactification process .
also , we present some solutions to the corresponding wheeler - dewitt ( wdw ) equation in the context of standard quantum cosmology and we claim that these quantum solution are generic in the moduli scalar field for all bianchi class a models . also we gives the relation to these solutions for asymptotic behavior to large argument in the corresponding quantum solution in the gravitational variables and is compared with the bohm s solutions , finding that this corresponds to lowest - order wkb approximation . .
And you have already written the first three sentences of the full article: in the last years there have been several attempts to understand the diverse aspects of cosmology , as the presence of stable vacua and inflationary conditions , in the framework of supergravity and string theory @xcite .
one of the most interesting features emerging from these type of models consists on the study of the consequences of higher dimensional degrees of freedom on the cosmology derived from four - dimensional effective theories @xcite .
furthermore , it has been pointed out that the presence of extra dimensions leads to an interesting connection with the ekpyrotic model @xcite , which generated considerable activity @xcite . the essential ingredient in these models.
Please generate the next two sentences of the article | ( see for instance @xcite ) is to consider an effective action with a graviton and a massless scalar field , the dilaton , describing the evolution of the universe , while incorporating some of the ideas of pre - big - bang proposal @xcite in that the evolution of the universe began in the far past .
on the other hand , it is well known that relativistic theories of gravity such as general relativity or string theories are invariant under reparametrization of time . |
6,054 | Suppose that you have an abstract for a scientific paper: in this paper we propose a scheme for quasi - perfect state transfer in a network of dissipative harmonic oscillators .
we consider ideal sender and receiver oscillators connected by a chain of nonideal transmitter oscillators coupled by nearest - neighbor resonances . from the algebraic properties of the dynamical quantities describing the evolution of the network state , we derive a criterion , fixing the coupling strengths between all the oscillators , apart from their natural frequencies , enabling perfect state transfer in the particular case of ideal transmitter oscillators .
our criterion provides an easily manipulated formula enabling perfect state transfer in the special case where the network nonidealities are disregarded . by adjusting the common frequency of the sender and the receiver oscillators to be out of resonance with that of the transmitters ,
we demonstrate that the sender s state tunnels to the receiver oscillator by virtually exciting the nonideal transmitter chain .
this virtual process makes negligible the decay rate associated with the transmitter line on the expenses of delaying the time interval for the state transfer process .
apart from our analytical results , numerical computations are presented to illustrate our protocol . .
And you have already written the first three sentences of the full article: a great deal of attention has been devoted recently to the subject of perfect state transfer ( pst ) in quantum networks .
since an actual quantum processor would require , in fact , the ability to transfer quantum information between spatially separated interacting systems composing a network , protocols have been established for pst in many different and general contexts . among the several interesting theoretical contributions , aiming to advance the understanding and eventual implementation of a quantum processor ,
the construction of effective two - qubit gates from pst between distant nodes in engineered bosonic and fermionic networks was proposed @xcite ..
Please generate the next two sentences of the article | a general formalism of the problem of pst in networks of any topology and coupling configuration was also developed @xcite .
focusing on spin chains , pst has been pursued in networks extending beyond the nearest - neighbor couplings @xcite , and a class of qubit networks allowing pst of any state in a fixed period of time has been devised @xcite . |
6,055 | Suppose that you have an abstract for a scientific paper: we shall argue in this paper that a central piece of modern physics does not really belong to physics at all but to elementary probability theory . given a joint probability distribution j on a set of random variables containing x and y ,
define a link between x and y to be the condition x = y on j. define the _ state _ d of a link x = y as the joint probability distribution matrix on x and y without the link .
the two core laws of quantum mechanics are the born probability rule , and the unitary dynamical law whose best known form is the schrodinger s equation .
von neumann formulated these two laws in the language of hilbert space as prob(p ) = trace(pd ) and dt = td respectively , where p is a projection , d and d are ( von neumann ) density matrices , and t is a unitary transformation .
we ll see that if we regard link states as density matrices , the algebraic forms of these two core laws occur as completely general theorems about links .
when we extend probability theory by allowing cases to count negatively , we find that the hilbert space framework of quantum mechanics proper emerges from the assumption that all d s are symmetrical in rows and columns . on the other hand ,
markovian systems emerge when we assume that one of every linked variable pair has a uniform probability distribution . by representing quantum and markovian structure in this way
, we see clearly both how they differ , and also how they can coexist in natural harmony with each other , as they must in quantum measurement , which we ll examine in some detail . looking beyond quantum mechanics ,
we see how both structures have their special places in a much larger continuum of formal systems that we have yet to look for in nature .
6.0 in 8.6 in -0.25truein 0.30truein 0.30truein = 1.5pc slac pub-7890 + august 1998 + * process , system , causality , and quantum mechanics * + _ * a psychoanalysis of animal faith * _ tom etter + 112 blackburn avenue + menlo park , california 940252704 + and + h. pierre....
And you have already written the first three sentences of the full article: the term ` animal faith ' in our subtitle is taken from the title of santayana s book skepticism and animal faith"@xcite ; it refers to what gets us through the day and keeps our thought processes going even through our spells of radical doubt .
santayana was concerned to delimit animal faith and to contrast it with other , presumably higher , things .
our agenda here is quite different and is closer to kant s : it is to articulate and transform into explicit principles the animal faith implicit in certain of our concepts that play a key role in science ..
Please generate the next two sentences of the article | once this is done , once these principles become explicit , we ll find that they take on a new life of their own , and are full of surprises .
first , they reveal the simple mathematical structure that unifies quantum and classical . |
6,056 | Suppose that you have an abstract for a scientific paper: the azimuthal anisotropy parameter @xmath0 has been measured with high statistics for identified hadrons in @xmath1au+au collisions with the star experiment . at
high transverse momentum @xmath2 a strong @xmath0 for @xmath3 and @xmath4 is observed . in the intermediate @xmath5 region ,
number - of - constituent - quark scaling was tested to high precision .
a detailed comparison of @xmath0 for the multi - strange hadrons @xmath6 , @xmath7 , and @xmath8 with other particle species substantiates the development of collectivity among partons in the early phase of the collisions at rhic . .
And you have already written the first three sentences of the full article: the study of ultra - relativistic heavy - ion collisions provides insight into properties of very high density nuclear matter .
since the observed particle distributions to first order only reflect the conditions in the final state of the system , signatures originating from the early stage are needed to conclude whether the system passes through a partonic phase .
this is one necessary step to identify the predicted state of matter called the quark - gluon plasma ; the other one being the proof that the system is thermalized ..
Please generate the next two sentences of the article | one observable which is sensitive to the early stage of the collision is the second harmonic coefficient , @xmath0 , of the fourier expansion of the azimuthal momentum distribution , called elliptic flow @xcite . in non - central collisions
the initial spatial anisotropy is transformed into an anisotropy in momentum - space if sufficient interactions occur among the constituents within the system . |
6,057 | Suppose that you have an abstract for a scientific paper: the electronic , phonon , and thermoelectric properties of a two - dimensional hfs@xmath0 monolayer are investigated by using the first - principles calculations combined with the boltzmann transport theory .
the band valleys of the hfs@xmath0 monolayer can be effectively tuned by the applied biaxial strain . the seebeck coefficient and therefore the peak value of the power factor ( with the relaxation time inserted ) increase
when the degeneracy of the band valleys is increased by the strain . when no strain is applied , the hfs@xmath0 monolayer is an excellent n - type thermoelectric material , while the thermoelectric performance of the p - type doped one is poor .
the applied tensile strain of 6% can increase the room - temperature @xmath1 value of the p - type doped system to 3.67 , which is five times larger than that of the unstrained one .
the much more balanced @xmath1 values of the p- and n - type doping are favorable for fabrication of both p- and n - legs of thermoelectric modules .
our results indicate that the thermoelectric performance of the hfs@xmath0 monolayer can be greatly improved by the valley engineering through the method of strain . .
And you have already written the first three sentences of the full article: with most of our used energy being lost as waste heat , there is a growing need for high - performance thermoelectric materials that can directly and reversibly convert heat into electricity .
the efficiency of a thermoelectric material is determined by the dimensionless figure of merit @xmath2 , where @xmath3 is the seebeck coefficient , @xmath4 is the electrical conductivity , @xmath5 is the temperature , and @xmath6 and @xmath7 are the electronic and phonon thermal conductivities , respectively . to obtain a high @xmath1 value , one must try to increase the power factor ( pf=@xmath8 ) and/or decrease the thermal conductivity
. however , the transport coefficients ( @xmath3 , @xmath4 , @xmath6 and @xmath7 ) are not independently tunable because they all depend strongly on the details of the band structure and the scattering of the charge carriers . as a result.
Please generate the next two sentences of the article | , it is still a challenge to obtain high @xmath1 thermoelectric materials , hindering their wide applications .
several successful concepts have been developed to increase the @xmath1 value , such as the use of low dimensionality,@xcite which could enhance the pf due to the sharper density of states ( dos ) near the fermi energy or reduce the thermal conductivity originating from the increased phonon scattering . |
6,058 | Suppose that you have an abstract for a scientific paper: we discuss a recently demonstrated type of microwave spectroscopy of trapped ultra - cold atoms known as `` echo spectroscopy '' [ m.f .
andersen et .
al . , phys .
rev .
lett .
, in press ( 2002 ) ] .
echo spectroscopy can serve as an extremely sensitive experimental tool for investigating quantum dynamics of trapped atoms even when a large number of states are thermally populated .
we show numerical results for the stability of eigenstates of an atom - optics billiard of the bunimovich type , and discuss its behavior under different types of perturbations .
finally , we propose to use special geometrical constructions to make a dephasing free dipole trap . .
And you have already written the first three sentences of the full article: the subject of decoherence of a quantum system has witnessed a renewed interest in the last years .
in addition to being central to our understanding of the transition from quantum to classical physics@xcite , it is of outmost importance in the blooming field of quantum information@xcite , where decoherence or dephasing represent loss of information . a quantum superposition state `` collapses '' due to the dissipative interaction with the environment ( e.g. in the case of trapped atoms
, the coupling to the electro - magnetic vacuum leads to spontaneous scattering of photons ) ..
Please generate the next two sentences of the article | this interaction is irreversible in nature . on the other hand ,
the macroscopic ( ensemble averaged ) response of a quantum system prepared in a superposition state decays due to the dephasing resulting from local variations in the evolution of the system ( e.g. inhomogeneous broadening ) . by stimulating an effective time reversal |
6,059 | Suppose that you have an abstract for a scientific paper: recently we proposed a new approach to the testing of dark energy models based on the observational data . in that work we focused particularly on quintessence models for demonstration and invoked a widely used parametrization of the dark energy equation of state . in this paper
we take the more recent sn ia , cmb and bao data , invoke the same parametrization , and apply this method of consistency test to five categories of dark energy models , including the @xmath0cdm model , the generalized chaplygin gas , and three quintessence models : exponential , power - law and inverse - exponential potentials .
we find that the exponential potential of quintessence is ruled out at the @xmath1 confidence level , while the other four models are consistent with data .
this consistency test can be efficiently performed since for all models it requires the constraint of only a single parameter space that by choice can be easily accessed . .
And you have already written the first three sentences of the full article: compelling evidences from type ia supernovae ( sn ia ) and other cosmological observations show that the expansion of the universe is undergoing an accelerating stage at late times ( see ref . for reviews ) . within the framework of general relativity and assuming homogeneity and isotropy
, this indicates that there should exist an energy source , termed dark energy , which provides a significant negative pressure to cause this acceleration . thus far
the nature of dark energy remains unresolved and is generally regarded as one of the most tantalizing problems in cosmology . while a positive cosmological constant remains the simplest realization of dark energy , current observational data have not ruled out the possibility of a time - evolving dark energy.@xcite as one awaits more information from the future observations , the constraining power of the next - generation observations and new analysis methods are being pursued.@xcite@xmath2@xcite many dark energy models have been proposed and studied . for the cosmological constant , its value has been constrained by observations ( see ref . , for example ) ..
Please generate the next two sentences of the article | the quintessence model , which invokes a time - varying scalar field,@xcite@xmath2@xcite generally allows its energy density and equation of state to evolve with time .
there are various quintessence models with different potential forms ( see , refs . |
6,060 | Suppose that you have an abstract for a scientific paper: we analyze the mixing behavior of the biased exclusion process on a path of length @xmath0 as the bias @xmath1 tends to @xmath2 as @xmath3 .
we show that the sequence of chains has a pre - cutoff , and interpolates between the unbiased exclusion and the process with constant bias . as the bias increases , the mixing time undergoes two phase transitions : one when @xmath1 is of order @xmath4 , and the other when @xmath1 is order @xmath5 . .
And you have already written the first three sentences of the full article: suppose @xmath6 particles are placed on vertices of the @xmath0-path , with no site multiply occupied .
the _ biased exclusion process _
is the markov chain @xmath7 with transitions as follows : * choose uniformly among the @xmath8 edges of the path , * if both vertices of the selected edge are either occupied or unoccupied , do nothing , * if there is exactly one particle on the edge , place it on the right vertex with probability @xmath9 and on the left with probability @xmath10 ..
Please generate the next two sentences of the article | the canonical case is when @xmath0 is even and @xmath11 .
this defines a reversible ergodic markov chain , which has a unique stationary distribution @xmath12 . |
6,061 | Suppose that you have an abstract for a scientific paper: we report on the co - existence of longitudinal and transverse oscillations in an active filament . on march 15@xmath0 2013 , a m1.1 class flare was observed in the active region ar 11692 .
a cme was found to be associated with the flare .
the cme generated a shock wave that triggered the oscillations in a nearby filament , situated at the south - west of the active region as observed from national solar observatory ( nso)_global oscillation network group_(gong ) h@xmath1 images . in this work
we report the longitudinal oscillations in the two ends of the filament , co - existing with the transverse oscillations .
we propose a scenario in which an incoming shock wave hits the filament obliquely and triggers both longitudinal and transverse oscillations .
using the observed parameters , we estimate the lower limit of the magnetic field strength .
we use simple pendulum model with gravity as the restoring force to estimate the radius of curvature .
we also calculate the mass accretion rate which causes the filament motions to damp quite fast . .
And you have already written the first three sentences of the full article: filaments support both longitudinal and transverse oscillations ( see , * ? ? ?
the oscillations in the filaments can be used to diagnose the local plasma conditions and magnetic field by applying the principle of mhd seismology ( see , * ? ? ?
* ; * ? ? ?.
Please generate the next two sentences of the article | these oscillations are broadly classified as large amplitude @xcite and small amplitude @xcite oscillations .
large amplitude transverse oscillations , where a filament oscillates as whole , are often associated with the disturbances coming from nearby flares . |
6,062 | Suppose that you have an abstract for a scientific paper: we report extensive spectroscopic and differential photometric @xmath0 observations of the active , detached , 1.309-day double - lined eclipsing binary i m vir , composed of a g7-type primary and a k7 secondary . with these observations
we derive accurate absolute masses and radii of @xmath1 , @xmath2 , @xmath3 , and @xmath4 for the primary and secondary , with relative errors under 2% .
the effective temperatures are @xmath5 k and @xmath6 k. the significant difference in mass makes this a favorable case for comparison with stellar evolution theory .
we find that both stars are larger than the models predict , by 3.7% for the primary and 7.5% for the secondary , as well as cooler than expected , by 100 k and 150 k , respectively .
these discrepancies are in line with previously reported differences in low - mass stars , and are believed to be caused by chromospheric activity , which is not accounted for in current models . the effect is not confined to low - mass stars : the rapidly - rotating primary of i m vir joins the growing list of objects of near - solar mass ( but still with convective envelopes ) that show similar anomalies .
the comparison with the models suggests an age of 2.4 gyr for the system , and a metallicity of [ fe / h ] @xmath7 that is consistent with other indications , but requires confirmation . .
And you have already written the first three sentences of the full article: our knowledge of stellar structure and evolution rests heavily on the comparison between theory and observation .
double - lined eclipsing binaries ( hereafter ebs ) have long been at the center of this process , since they allow the mass the most fundamental of all stellar properties as well as the radius to be determined to very high precision ( and accuracy ) , often as good as 1% , independently of the distance and independently of any calibrations .
such high precision enables stringent tests of theory , as described , e.g. , by @xcite . in the last decade.
Please generate the next two sentences of the article | or so it has become clear that stars in the lower main - sequence show significant discrepancies when compared to standard models
. studies of several key systems have shown unambiguously that the radii predicted by the models are systematically up to @xmath810% too small , and the temperatures @xmath85% too high ( see * ? ? ? * and references therein ) . |
6,063 | Suppose that you have an abstract for a scientific paper: the apparently repeating microlensing event ogle-2003-blg-095 is analyzed .
data were obtained from the ogle internet archive and exist in the public domain .
the source is relatively bright , with an unmagnified ( but possibly blended ) @xmath0-band magnitude of 15.58 , and the signal - to - noise ratio of the data is excellent .
the light curve shows two distinct , smooth peaks characteristic of a double microlensing event .
it can be modeled as either ( 1 ) microlensing by a binary lens or ( 2 ) microlensing of a binary source , with the latter model providing a statistically superior fit .
however due to apparent low - amplitude variability of the source , the interpretation is somewhat ambiguous .
ogle-2003-blg-095 is only the second possible case in the literature for microlensing of a well - resolved binary source . .
And you have already written the first three sentences of the full article: gravitational microlensing surveys were originally suggested by @xcite as a means of detecting dark matter in the galaxy in the form of massive compact objects , commonly abbreviated as machos following @xcite .
various efforts were undertaken to search for such objects , including the optical gravitational lensing experiment ( ogle ; @xcite ) , the macho project ( e.g. , @xcite ) , and several others .
currently ongoing projects , most notably ogle and moa @xcite , are detecting hundreds and dozens of new microlensing events each year , respectively ..
Please generate the next two sentences of the article | the new events found by these groups are made public in real time to maximize scientific gain by enabling follow - up of interesting objects by the astronomical community .
in addition to the possibility of detecting dark matter machos , microlensing surveys also offer the interesting opportunity to study the populations of stellar lenses ( which constitute at least a significant fraction of all events ) and sources . |
6,064 | Suppose that you have an abstract for a scientific paper: boundary actions for three - dimensional quantum gravity in the discretized formalism of ponzano - regge are studied with a view towards understanding the boundary degrees of freedom .
these degrees of freedom postulated in the holography hypothesis are supposed to be characteristic of quantum gravity theories .
in particular it is expected that some of these degrees of freedom reside on black hole horizons .
this paper is a study of these ideas in the context of a theory of quantum gravity that requires no additional structure such as supersymmetry or special gravitational backgrounds .
lorentzian as well as euclidean regimes are examined . some surprising relationships
to liouville theory and string theory in @xmath0 are found .
gr - qc/0002092 .
And you have already written the first three sentences of the full article: this article presents the calculation , using continuum and lattice methods , of boundary terms in 3-dimensional gravity .
the gravity theory is presented in first order palatini form , this being a particular example of the general class of bf models @xcite as this is the most convenient presentation for deriving the discretization .
we find a variety of boundary conditions , and discuss the significance of these for different types of boundaries in space - time ..
Please generate the next two sentences of the article | the bulk theory of three - dimensional gravity is well known to be a topological field theory , however it is also well known that three - dimensional topological field theories can give rise to non- topological boundary degrees of freedom , the classic example being the cs theory giving rise to a wzw model on the boundary @xcite . in the case of three dimensional gravity with cosmological constant , one can utilize a trick that relates the action to the difference of two cs actions , and then use the standard cs - wzw relationship , however the actual boundary conditions are a little more subtle . in three dimensions
this is relevant to the @xmath0 space , or more generally to btz black hole solutions . in this paper |
6,065 | Suppose that you have an abstract for a scientific paper: in this paper , we calculate the spectrum of scalar field fluctuations in a bouncing , asymptotically flat universe , and investigate the dependence of the result on changes in the physics on length scales shorter than the planck length which are introduced via modifications of the dispersion relation . in this model , there are no ambiguities concerning the choice of the initial vacuum state .
we study an example in which the final spectrum of fluctuations depends sensitively on the modifications of the dispersion relation without needing to invoke complex frequencies .
changes in the amplitude and in the spectral index are possible , in addition to modulations of the spectrum .
this strengthens the conclusions of previous work in which the spectrum of cosmological perturbations in expanding inflationary cosmologies was studied , and it was found that , for dispersion relations for which the evolution is not adiabatic , the spectrum changes from the standard prediction of scale - invariance . .
And you have already written the first three sentences of the full article: the dependence of the spectrum of cosmological fluctuations in an inflationary universe on hidden assumptions about the physics on length scales much smaller than the planck length has been recently studied in refs .
_ a priori _ this dependence comes about since in typical scalar - field - driven inflationary models the duration of the period of expansion is so long that the physical wavelengths of comoving modes which correspond to the present large - scale structure of the universe are much smaller than the planck length at the beginning of inflation . in weakly coupled scalar field models of inflation ,
the spectrum of fluctuations is calculated by assuming that fluctuation modes start out in the vacuum ( i.e. minimum energy density ) state at the beginning of inflation and subsequently evolve as determined by the equations of motion ..
Please generate the next two sentences of the article | it is hence not unreasonable to expect that modifications of the physics on trans - planckian scales could affect the final spectrum of fluctuations .
while the correct theory of trans - planckian physics is not known , possible effects of the new physics can be modeled by changes in the dispersion relation of the fields corresponding to linear cosmological fluctuations . |
6,066 | Suppose that you have an abstract for a scientific paper: we study the effect of enforcing exact conservation of charges in statistical models of particle production for systems as large as those relevant to relativistic heavy ion collisions . by using a numerical method developed for small systems ,
we have been able to approach the large volume limit keeping the exact canonical treatment of all relevant charges , namely baryon number , strangeness and electric charge .
hence , we hereby give the information needed in a hadron gas model whether the canonical treatment is necessary or not in actual cases .
comparison between calculations and experimental particle multiplicities is shown .
also , a discussion on relative strangeness chemical equilibrium is given . .
And you have already written the first three sentences of the full article: over the era of relativistic nuclear collisions , the statistical - thermal models have been widely used in the analysis of particle production . during the past few years
, these models have been successful in describing particle multiplicities in high energy nuclear reactions at the stage where inelastic collisions between hadrons cease ( chemical freeze - out ) , see e.g. @xcite . the easiest to handle , thence
the most used , statistical model calculational framework is based on the grand canonical ( gc ) ensemble . in the gc approach entropy.
Please generate the next two sentences of the article | is maximized using the constraints of conserved _ ensemble averages _ of energy and charges .
this allows the net charges to fluctuate from sample to sample even though the actual charges brought into the physical reactions were exactly same every time . in the large volume and energy limit |
6,067 | Suppose that you have an abstract for a scientific paper: various issues concerning the impact of inflationary models on parameter estimation from the cosmic microwave background are reviewed , with particular focus on the range of possible outcomes of inflationary models and on the amount which might be learnt about inflation from the microwave background . .
And you have already written the first three sentences of the full article: inflation @xcite maintains its position as the favourite model for the origin of structure in the universe .
the reasons are two - fold .
firstly , the gaussian adiabatic and nearly scale - invariant density perturbations that the usual models produce currently offer the best framework in which to interpret observational data on structures in the universe . and.
Please generate the next two sentences of the article | secondly , it is a extremely simple paradigm within which to make theoretical predictions ; for example the cmbfast program allows the prediction of microwave background anisotropies to better than one percent accuracy , and as yet calculations in the rival , much more theoretically challenging , topological defects theories @xcite lag some way behind @xcite . however , the inflationary paradigm is quite a broad one , and there exists a wide range of different implementations of the inflationary idea . in this article
i aim to give a flavour of the complexity of models which we might one day find ourselves forced to deal with , if we are to understand structure formation . |
6,068 | Suppose that you have an abstract for a scientific paper: we investigate the applicability of migdal eliashberg ( me ) theory by revisiting migdal s analysis within the dynamical mean - field theory framework .
first , we compute spectral functions , the quasi - particle weight , the self energy , renormalised phonon frequency and resistivity curves of the half - filled holstein model .
we demonstrate how me theory has a phase - transition - like instability at intermediate coupling , and how the engelsberg schrieffer ( es ) picture is complicated by low - energy excitations from higher order diagrams ( demonstrating that es theory is a very weak coupling approach ) . through consideration of the lowest - order vertex correction ,
we analyse the applicability of me theory close to this transition .
we find a breakdown of the theory in the intermediate coupling adiabatic limit due to a divergence in the vertex function .
the region of applicability is mapped out , and it is found that me theory is only reliable in the weak coupling adiabatic limit , raising questions about the accuracy of recent analyses of cuprate superconductors which do not include vertex corrections . .
And you have already written the first three sentences of the full article: the use of migdal eliashberg ( me ) theory for the study and analysis of electron - phonon systems is widespread . for conventional superconductors such as lead , where the electron - phonon coupling is higher than can be treated with bcs theory ,
me theory has been extremely successful for understanding the superconducting properties .
recently , a lot of researchers have been interested in an apparent kink in the electronic dispersion of cuprate supercondutors as determined from angle resolved photo - emission spectroscopy ( arpes ) , and their analysis / interpretation typically uses the related engelsberg schrieffer ( es ) result ( i.e. just the lowest order fock diagram ) @xcite ..
Please generate the next two sentences of the article | the es result divides excitations into long - lived ( coherent ) low - energy excitations , and rapidly decaying high - energy excitations , with a kink at the phonon energy .
es based analysis of arpes results suggests a large electron - phonon coupling in the cuprates , with estimates of the dimensionless coupling constant lying between @xmath0 and @xmath1 ( depending on doping ) and very large phonon frequencies of @xmath2 mev @xcite . there has also been a development of a maximum entropy technique for analysing cuprate superconductors which makes use of eliashberg theory @xcite . the analysis in ref . determines a dimensionless electron - phonon coupling of @xmath3 , but this is well above the @xmath4 value where one would normally expect perturbation theory to fail . |
6,069 | Suppose that you have an abstract for a scientific paper: recent observations of the ly@xmath0 forest show large - scale spatial variations in the intergalactic ly@xmath0 opacity that grow rapidly with redshift at @xmath1 , far in excess of expectations from empirically motivated models .
previous studies have attempted to explain this excess with spatial fluctuations in the ionizing background , but found that this required either extremely rare sources or problematically low values for the mean free path of ionizing photons . here
we report that much or potentially all of the observed excess likely arises from residual spatial variations in temperature that are an inevitable byproduct of a patchy and extended reionization process .
the amplitude of opacity fluctuations generated in this way depends on the timing and duration of reionization .
if the entire excess is due to temperature variations alone , the observed fluctuation amplitude favors a late - ending but extended reionization process that was roughly half complete by @xmath2 and that ended at @xmath3 . in this scenario ,
the highest opacities occur in regions that reionized earliest , since they have had the most time to cool , while the lowest opacities occur in the warmer regions that reionized most recently .
this correspondence potentially opens a new observational window into patchy reionization . .
And you have already written the first three sentences of the full article: when the first galaxies emerged @xmath4 million years after the big bang , their starlight reionized and heated the intergalactic hydrogen that had existed since cosmological recombination .
much is currently unknown about this process , including what spatial structure it had , when it started and completed , and even which sources drove it .
the ly@xmath0 forest provides one of the only robust constraints on this process , showing that it was at least largely complete by @xmath5 , when the universe was one billion years old @xcite ..
Please generate the next two sentences of the article | this letter argues that there exists another , potentially groundbreaking signature of reionization in the ly@xmath0 forest data . the amount of absorption in the ly@xmath0 forest can be quantified by the effective optical depth , @xmath6 , where @xmath7 $ ] is the transmitted fraction of a quasar s flux
, @xmath8 indicates an average over a segment of the forest of length @xmath9 , and @xmath10 is the optical depth in ly@xmath0 at location @xmath11 along a sightline . |
6,070 | Suppose that you have an abstract for a scientific paper: the observational limitations of astronomical surveys lead to significant statistical inference challenges .
one such challenge is the estimation of luminosity functions given redshift @xmath0 and absolute magnitude @xmath1 measurements from an irregularly truncated sample of objects .
this is a bivariate density estimation problem ; we develop here a statistically rigorous method which ( 1 ) does not assume a strict parametric form for the bivariate density ; ( 2 ) does not assume independence between redshift and absolute magnitude ( and hence allows evolution of the luminosity function with redshift ) ; ( 3 ) does not require dividing the data into arbitrary bins ; and ( 4 ) naturally incorporates a varying selection function .
we accomplish this by decomposing the bivariate density @xmath2 via @xmath3 where @xmath4 and @xmath5 are estimated nonparametrically , and @xmath6 takes an assumed parametric form .
there is a simple way of estimating the integrated mean squared error of the estimator ; smoothing parameters are selected to minimize this quantity .
results are presented from the analysis of a sample of quasars . .
And you have already written the first three sentences of the full article: astronomers commonly seek to estimate the _ space density _ of objects , and a sky survey such as the sloan digital sky survey ( sdss ) @xcite can yield a representative sample useful for this purpose , due to the assumed isotropy of the universe .
figure [ rawdata ] depicts redshift and absolute magnitude measurements for a sample of quasars given in @xcite .
these are a subset of the sdss quasar sample ( data release 3 ) , chosen to be statistically valid for purposes such as exploring the evolution with redshift of the luminosity function , i.e. the space density of quasars as a function of absolute magnitude ..
Please generate the next two sentences of the article | this paper describes a new method for estimating these luminosity functions , and presents results from the analysis of this quasar sample .
for the purposes of the statistical inference problem , imagine the dots in figure [ rawdata ] as observations of bivariate data @xmath7 from some distribution with probability density @xmath2 , i.e. the probability that a randomly chosen quasar falls in a region @xmath8 is @xmath9 . |
6,071 | Suppose that you have an abstract for a scientific paper: we quantitatively analyze a familiar classroom demonstration , van waltenhofen s eddy current pendulum , to predict the damping effect for a variety of plate geometries from first principles .
results from conformal mapping , finite element simulations and a simplified model suitable for introductory classes are compared with experiments . .
And you have already written the first three sentences of the full article: eddy currents are induced electric currents in a conducting material that result when either the object moves through a nonuniform magnetic field or is stationary but subject to a time - changing magnetic field .
they were first observed by franois arago@xcite but it was not until michael faraday s discovery of induction@xcite that the mechanism of this phenomenon was understood .
a pioneering experiment to quantify the heat dissipated by the eddy currents , and hence connect electromagnetism to thermodynamics , is von waltenhofen s pendulum@xcite [ figure [ fig : schematic](a)(c ) ] ..
Please generate the next two sentences of the article | the bob of the pendulum is a non ferromagnetic conducting plate which swings between the poles of an electromagnet , generating circulating eddy currents .
the dissipative eddy currents tend to oppose the motion of the bob , and hence damp the pendulum . |
6,072 | Suppose that you have an abstract for a scientific paper: we define a c*-hull for a * -algebra , given a notion of integrability for its representations on hilbert modules .
we establish a local global principle which , in many cases , characterises integrable representations on hilbert modules through the integrable representations on hilbert spaces .
the induction theorem constructs a c*-hull for a certain class of integrable representations of a graded * -algebra , given a c*-hull for its unit fibre . .
And you have already written the first three sentences of the full article: savchuk and schmdgen @xcite introduce a method to define and classify the integrable representations of certain * -algebras by an inductive construction .
the original goal of this article was to clarify this method and thus make it apply to more situations .
this has led me to reconsider some foundational aspects of the theory of representations of * -algebras by unbounded operators ..
Please generate the next two sentences of the article | this is best explained by formulating an induction theorem that is inspired by @xcite .
let @xmath0 be a discrete group with unit element @xmath1 . |
6,073 | Suppose that you have an abstract for a scientific paper: it is now believed that the scaling exponents of moments of velocity increments are anomalous , or that the departures from kolmogorov s ( 1941 ) self - similar scaling increase nonlinearly with the increasing order of the moment .
this appears to be true whether one considers velocity increments themselves or their absolute values .
however , moments of order lower than 2 of the absolute values of velocity increments have not been investigated thoroughly for anomaly . here
, we discuss the importance of the scaling of non - integer moments of order between + 2 and @xmath0 , and obtain them from direct numerical simulations at moderate reynolds numbers ( taylor microscale reynolds numbers @xmath1 450 ) and experimental data at high reynolds numbers ( @xmath2 10,000 ) . the relative difference between the measured exponents and kolmogorov s prediction increases as the moment order decreases towards @xmath0 , thus showing that the anomaly that is manifest in high - order moments is present in low - order moments as well .
this conclusion provides a motivation for seeking a theory of anomalous scaling as the order of the moment vanishes .
such a theory does not have to consider rare events which may be affected by non - universal features such as shear and so may be regarded as advantageous to consider and develop . .
And you have already written the first three sentences of the full article: the moments of velocity differences over spatial scales of size @xmath3 , the so - called structure functions , provide useful measures of the statistical description of fluid turbulence ( kolmogorov 1941a , b ) .
in particular , the longitudinal structure functions defined as @xmath4^n \big \rangle \label{sn}\ ] ] have been studied extensively . here
, @xmath5 is the velocity vector at position @xmath6 , and @xmath7 is the unit vector along the separation vector @xmath8 ..
Please generate the next two sentences of the article | the special interest in structure functions comes in part from an exact result , known as the 4/5-ths law , @xmath9 valid in the inertial range of scales ( @xmath10 where @xmath11 is the kolmogorov scale characterizing the dissipative scale of motion and @xmath12 is a suitable large scale of turbulence ) . in part
, the interest is spurred by the operational ease with which longitudinal structure functions can be obtained from experimental data if one makes the so - called taylor s hypothesis ( taylor 1935 ) . |
6,074 | Suppose that you have an abstract for a scientific paper: the interpolation from supersymmetric to non - supersymmetric heterotic theories is studied , via the scherk - schwarz compactification of supersymmetric @xmath0 theories to @xmath1 .
a general modular - invariant scherk - schwarz deformation is deduced from the properties of the @xmath0 theories at the endpoints , which significantly extends previously known examples . this wider class of non - supersymmetric @xmath1 theories is a promising prospect for the development of viable sm - like phenomenology .
the full one - loop cosmological constant of such theories is studied as a function of compactification radius for a number of cases , and the following interpolating configurations are found : two supersymmetric @xmath0 theories related by a @xmath2-duality transformation , with intermediate @xmath1 maximum or minimum at the string scale ; a non - supersymmetric @xmath0 theory interpolating to a supersymmetric @xmath0 theory , with the @xmath1 theory possibly having an ads minimum ; a `` metastable '' non - supersymmetric @xmath0 theory interpolating via a @xmath1 theory to a supersymmetric @xmath0 theory . .
And you have already written the first three sentences of the full article: an important question in string phenomenology is how and when supersymmetry ( susy ) is broken .
a great deal of effort has been devoted to frameworks in which it is broken non - perturbatively in the supersymmetric effective field theory .
much less effort has been devoted to string theories that are non - supersymmetric by construction . on the face of it ,.
Please generate the next two sentences of the article | the trade off for the second option , is that non - supersymmetric string models do not have the stability properties of supersymmetric ones .
however it can be argued that as long as the susy breaking is spontaneous and parametrically smaller than the string scale , the associated instability is under perturbative control @xcite . |
6,075 | Suppose that you have an abstract for a scientific paper: in this paper we compare three different formalisms that can be used in the area of models for distributed , concurrent and mobile systems .
in particular we analyze the relationships between a process calculus , the _ fusion calculus _ , graph transformations in the _ synchronized hyperedge replacement _ with hoare synchronization ( hshr ) approach and _ logic programming_. we present a translation from fusion calculus into hshr ( whereas fusion calculus uses milner synchronization ) and prove a correspondence between the reduction semantics of fusion calculus and hshr transitions .
we also present a mapping from hshr into a transactional version of logic programming and prove that there is a full correspondence between the two formalisms .
the resulting mapping from fusion calculus to logic programming is interesting since it shows the tight analogies between the two formalisms , in particular for handling name generation and mobility .
the intermediate step in terms of hshr is convenient since graph transformations allow for multiple , remote synchronizations , as required by fusion calculus semantics . to appear in theory and practice of logic programming ( tplp ) .
fusion calculus , graph transformation , synchronized hyperedge replacement , logic programming , mobility .
And you have already written the first three sentences of the full article: in this paper we compare different formalisms that can be used to specify and model systems which are distributed , concurrent and mobile , as those that are usually found in the global computing area .
+ global computing is becoming very important because of the great development of networks which are deployed on huge areas , first of all internet , but also other kinds of networks such as networks for wireless communications . in order to build and program these networks
one needs to deal with issues such as reconfigurability , synchronization and transactions at a suitable level of abstraction ..
Please generate the next two sentences of the article | thus powerful formal models and tools are needed .
until now no model has been able to emerge as the standard one for this kind of systems , but there are a lot of approaches with different merits and drawbacks . |
6,076 | Suppose that you have an abstract for a scientific paper: in this paper , we develop an @xmath0-time algorithm to find a half - integral node - capacitated multiflow of the maximum total flow - value in a network with @xmath1 nodes , @xmath2 edges , and @xmath3 terminals , where @xmath4 denotes the time complexity of solving the maximum submodular flow problem in a network with @xmath5 edges , @xmath6 edges , and the complexity @xmath7 of computing the exchange capacity of the submodular function describing the problem . by using fujishige - zhang algorithm for submodular flow , we can find a maximum half - integral multiflow in @xmath8 time .
this is the first combinatorial strongly polynomial time algorithm for this problem .
our algorithm is designed on the basis of a developing theory of discrete convex functions on certain graph structures .
applications include ellipsoid - free " combinatorial implementations of a 2-approximation algorithm for the minimum node - multiway cut problem by garg , vazirani , and yannakakis .
keywords : node - capacitated multiflow , discrete convex analysis , submodular flow , node - multiway cut .
And you have already written the first three sentences of the full article: a node - capacitated undirected network is a quadruple @xmath9 of node set @xmath10 , ( undirected ) edge set @xmath11 , a specified subset @xmath12 of nodes , called _
terminals _ , and a nonnegative integer - valued node capacity @xmath13 on nonterminal nodes . an _
@xmath12-path _ is a path connecting distinct terminals ..
Please generate the next two sentences of the article | a ( node - capacitated ) _ multiflow _ is a pair @xmath14 of a set @xmath15 of @xmath12-paths and a flow - value function @xmath16 satisfying the node - capacity constraint : @xmath17 the total flow - value of a multiflow @xmath18 is defined as @xmath19 .
a multiflow is called _ maximum _ if it has the maximum total flow - value among all possible multiflows . |
6,077 | Suppose that you have an abstract for a scientific paper: the well - founded semantics is one of the most widely studied and used semantics of logic programs with negation . in the case of finite propositional programs , it can be computed in polynomial time , more specifically , in @xmath0 steps , where @xmath1 denotes the total number of occurrences of atoms in a logic program @xmath2 .
this bound is achieved by an algorithm introduced by van gelder and known as the alternating - fixpoint algorithm .
improving on the alternating - fixpoint algorithm turned out to be difficult . in this paper
we study extensions and modifications of the alternating - fixpoint approach .
we then restrict our attention to the class of programs whose rules have no more than one positive occurrence of an atom in their bodies . for programs in that class
we propose a new implementation of the alternating - fixpoint method in which false atoms are computed in a top - down fashion .
we show that our algorithm is faster than other known algorithms and that for a wide class of programs it is linear and so , asymptotically optimal .
[ firstpage ] .
And you have already written the first three sentences of the full article: the well - founded semantics was introduced in @xcite to provide 3-valued interpretations to logic programs with negation . since its introduction , the well - founded semantics has become one of the most widely studied and most commonly accepted approaches to negation in logic programming @xcite .
it was implemented in several top - down reasoning systems , most prominent of which is xsb @xcite .
the well - founded semantics is closely related to the stable - model semantics @xcite , another major approach to logic programs with negation ..
Please generate the next two sentences of the article | the well - founded semantics approximates the stable - model semantics @xcite .
moreover , computing the well - founded model of propositional programs is polynomial @xcite while computing stable models is np - hard @xcite . |
6,078 | Suppose that you have an abstract for a scientific paper: we investigate coherence in one- and two - photon optical systems , both theoretically and experimentally . in the first case
, we develop the density operator representing a single photon state subjected to a non - dissipative coupling between observed ( polarization ) and unobserved ( frequency ) degrees of freedom .
we show that an implementation of `` bang - bang '' quantum control protects photon polarization information from certain types of decoherence . in the second case
, we investigate the existence of a decoherence - free " subspace of the hilbert space of two - photon polarization states under the action of a similar coupling .
the density operator representation is developed analytically and solutions are obtained numerically . .
And you have already written the first three sentences of the full article: decoherence in two - state quantum systems is a significant obstacle to the realization of proposed quantum information technologies .
coupling between quantum bit ( `` qubit '' ) states and unobserved environmental degrees of freedom leads to decoherence effects which limit the practical implementation of proposed quantum algorithms @xcite .
photon modes , including polarization and spatial modes , provide an easily accessible system in which simple quantum circuits can be investigated @xcite . here , we examine the process of decoherence by subjecting single photons to a controllable birefringent `` environment '' and observing the evolution of the polarization state . in section [ one - photon ].
Please generate the next two sentences of the article | , we investigate the evolution of a single photon state under the action of a unitary coupling between polarization and frequency modes .
such non - dissipative `` phase errors '' give rise to decoherence effects , whereby the photon evolves from a definite polarization state to an unpolarized state . |
6,079 | Suppose that you have an abstract for a scientific paper: through the direct decoration transformation approach , we obtain a general solution for the pentagonal ising model , showing its equivalence to the isotropic free - fermion eight - vertex model .
we study the ground - state phase diagram , in which one ferromagnetic ( fm ) state , one ferrimagnetic ( fim ) state , and one frustrated state are found . using the exact solution of the pentagonal ising model
, we discuss the finite - temperature phase diagrams and find a phase transition between the fim state and the disordered state as well as a phase transition between the disordered state and the fm state .
we also discuss some additional remarkable properties of the model , such as the magnetization , entropy , and specific heat , at finite temperature and at its low - temperature asymptotic limit .
because of the influence of the second - order phase transition between the frustrated and ferromagnetic phases , we obtain surprisingly low values of the entropy and the specific heat until the critical temperature is reached . , .
And you have already written the first three sentences of the full article: over the past six decades , much effort has been devoted to determining the critical behavior of statistical properties of lattice models , which would allow a deeper understanding of order - disorder phenomena in magnetic solids .
following onsager s pioneering exact solution for the square lattice ising model @xcite , exact solutions were also obtained for other regular two - dimensional lattice structures @xcite . in particular ,
exact results have been attained for the triangular , honeycomb , kagome , and bathroom - tile lattices @xcite , @xcite , @xcite , as well as for two - dimensional models , such as the union jack ( centered square ) @xcite and the square kagome @xcite lattices ..
Please generate the next two sentences of the article | geometrical frustration is mainly based on the triangle and tetrahedron structures , but it was also found in the ising model on a pentagonal penrose lattice proposed by waldor _ _ et al.__@xcite and solved exactly using the transfer matrix approach .
more recently urumov @xcite considered the ising model on the cairo pentagonal lattice using the decoration transformation @xcite . |
6,080 | Suppose that you have an abstract for a scientific paper: the complete one - loop self energies ( real and imaginary parts ) for photons , gluons , electrons and quarks at finite temperature are calculated numerically and compared to the results of the hard thermal loop ( htl ) approximation used for the resummation technique of braaten and pisarski . in this way
some light is shed on the validity of the weak coupling limit assumption ( @xmath0 ) or equivalently the high temperature assumption , on which the htl approximation is based .
furthermore , the gauge dependence of the fermion self energy beyond the htl approximation is considered .
finally the dispersion relations following from the real part of the self energies are compared to the htl results . .
And you have already written the first three sentences of the full article: in relativistic plasmas , such as a quark - gluon plasma ( qgp ) possibly formed in relativistic heavy ion collisions or a qed plasma in a supernova explosion , and in relativistic , degenerate matter , as e.g. strange quark stars , medium effects are of great importance .
for example , the originally massless or light particles of the system acquire an effective mass caused by the interactions with the other particles of the system . also screening effects due to the presence of ( color ) charges in the system ( debye screening ) prevent or at least reduce infrared singularities coming from the long range interactions in qed or qcd .
these effects can be calculated from the self energy of the particles ..
Please generate the next two sentences of the article | evaluated perturbatively to lowest order at high temperature @xmath1 or density ( corresponding to a large chemical potential @xmath2 ) the effective mass and the debye mass are of the order @xmath3 or @xmath4 , where @xmath5 is the coupling constant .
these masses can be large compared to the bare masses , which are negligible at high temperature . the dispersion relations of the quasiparticles thus deviate from the ones of bare particles leading to important modifications of the equation of state @xcite . |
6,081 | Suppose that you have an abstract for a scientific paper: the magnetic orders in na@xmath0iro@xmath1 and @xmath2rucl@xmath1 , honeycomb systems with strong spin - orbit coupling and correlations , have been recently described by models with the dominant kitaev interactions . in this work
we discuss how the orientation of the magnetic order parameter is selected in this class of models .
we show that while the order - by - disorder mechanism in the models with solely kitaev anisotropies always select cubic axes as easy axes for magnetic ordering , the additional effect of other small bond - dependent anisotropies , such as , e.g. , @xmath3-terms , lead to a deviation of the order parameter from the cubic directions .
we show that both the zigzag ground state and the face - diagonal orientation of the magnetic moments in na@xmath0iro@xmath1 can be obtained within the @xmath4 model in the presence of perturbatively small @xmath3-terms .
we also show that the zigzag phase found in the nearest neighbor kitaev - heisenberg model , relevant for @xmath2rucl@xmath1 , has some stability against the @xmath3-term . .
And you have already written the first three sentences of the full article: the long - standing quest for a solid state realization of the kitaev honeycomb model@xcite has triggered much of the experimental and theoretical interest in 4d and 5d compounds with two- and three - dimensional tri - coordinated lattices , in which the interplay of the strong spin - orbit coupling ( soc ) and electronic correlations leads to the dominance of the strongly anisotropic kitaev - like interactions.@xcite a lot of experimental effort has been focused on iridium oxides belonging to the a@xmath0iro@xmath1 family@xcite and , more recently , to @xmath2rucl@xmath1.@xcite the kitaev honeycomb model belongs to the class of the compass models .
it is intrinsically frustrated due to the bond - depended nature of the interactions . in the quantum case
, this frustration leads to the appearance of the non - trivial quantum spin liquid ( qsl ) phase with fractionalized excitations , dubbed kitaev qsl.@xcite kitaev qsl is not a unique example of non - trivial ground states of the compass models , @xcite however , it is probably the only one which allows an exact analytic solution.
Please generate the next two sentences of the article | . in honeycomb iridates and ruthenates , the magnetic degree of freedom described by an effective magnetic moment @xmath5 , arises in the presence of strong soc from electrons occupying @xmath6-manifold of states of ir@xmath7 and ru@xmath8 ions . in a@xmath0iro@xmath1 compounds ,
edge - shared iro@xmath9 octahedra provide 90@xmath10 paths for the dominant nearest neighbor kitaev coupling between iridium magnetic moments . |
6,082 | Suppose that you have an abstract for a scientific paper: we study theoretically the effects of spatial confinement on the phoretic motion of a dissolved particle driven by composition gradients generated by chemical reactions of its solvent , which are active only on certain parts of the particle surface .
we show that the presence of confining walls increases in a similar way both the composition gradients and the viscous friction , and the overall result of these competing effects is an increase in the phoretic velocity of the particle . for the case of steric repulsion only between the particle and the product molecules of the chemical reactions ,
the absolute value of the velocity remains nonetheless rather small . .
And you have already written the first three sentences of the full article: recent years have witnessed a growing technological , experimental , and theoretical interest in scaling standard machinery down to micro- and nano - scales as needed for the development of `` lab on a chip '' devices . for applications in ,
e.g. , drug - delivery systems or micromechanics one of the most challenging problems at this stage is to develop ways to enable small - scale objects to perform autonomous , controlled motion @xcite .
although the research in this area is still in its early stages , several such proposals have already been tested experimentally ( see , e.g. , refs . ) ..
Please generate the next two sentences of the article | a review of the recent progress in this field can be found in ref . .
whitesides and co - workers proposed a design of self - propelling devices based on an asymmetric decoration of the surface of small objects by catalytic , active sites promoting a chemical reaction in the surrounding liquid medium @xcite . |
6,083 | Suppose that you have an abstract for a scientific paper: the spatial and temporal distributions of solar filaments were analyzed using data from the meudon observatory for the period 1919 - 2003 and the kislovodsk mountain astronomical station for the period 1979 - 2014 .
we scanned @xmath0 solar synoptic charts on which the filaments were isolated and digitized .
the data on each filament comprise its location , length , area , and other geometrical characteristics .
the temporal distributions of the number and total length of the filaments have been obtained .
we also found latitudinal migration of filament locations with the solar cycle , and analyzed the longitudinal distribution and asymmetry of filaments in the northern and southern hemispheres , and other properties of their distribution .
the tilt angles of filaments with respect the solar equator ( @xmath1 ) were analyzed .
on average , the eastern tips of filaments are closer to the poles than the western ones ( @xmath2 ) . on the other hand , the filaments in the polar regions ( @xmath3 , where @xmath4 is the latitude ) usually have negative tilts ( @xmath5 ) .
the tilt angles vary with the phases of the 11 year sunspot cycle and are at their highest values in the epoch of the activity maximum . in the century - long modulation of the solar activity ( gleissberg cycle ) ,
the mean tilt angles of filaments in the mid - latitude zone ( @xmath6 ) were maximum in the middle of the 20th century in solar sunspot cycles 18 - 19 .
we hereby propose using the statistical properties of solar filaments as an additional coherent measure of manifestation of the solar cycle which covers all latitudes and for which almost a century long systematically calibrated data series is available . .
And you have already written the first three sentences of the full article: the appearance of filaments on the solar disk is associated with the distribution of large - scale magnetic fields and magnetic fields of active regions ( ar ) .
the filaments are observed virtually at all latitudes in the solar atmosphere .
systematic @xmath0 observations have been carried out approximately since 1915 at the kodaikanal observatory ( india ) , since 1919 at the meudon observatory ( france ) ( spectroscopic observations ) , and since 1959 at the kislovodsk mountain astronomical station of the main ( pulkovo ) astronomical observatory of russian academy of sciences ..
Please generate the next two sentences of the article | the filaments observed in the @xmath0 line in the solar chromospheres are one of the basic indices of solar activity ( see the review by @xcite ) .
solar filaments arise in the vicinity of the magnetic field polarity inversion line ( @xcite , @xcite , @xcite ) . as a rule , |
6,084 | Suppose that you have an abstract for a scientific paper: the physical mechanism underlying scattering properties of matter wave gap - solitons by linear optical lattice defects is investigated .
the occurrence of repeated reflection , transmission and trapping regions for increasing strengths of an optical lattice defect are shown to be due to impurity modes inside the defect potential with chemical potentials and numbers of atoms matching corresponding quantities of an incoming gap - soliton . for gap - solitons with chemical potentials very close to band edges ,
the number of resonances observed in the scattering coincides with the number of bound states which can exist in the defect potential for the given defect strength .
the dependence of the positions and widths of the transmission resonant on the incoming gap - soliton velocities are investigated by means of a defect mode analysis and effective mass theory .
the comparisons with direct integrations of the gross - pitaevskii equation provide a very good agreement confirming the correctness of our interpretation . the possibility of multiple resonant transmission through arrays of optical lattice defects is also demonstrated .
in particular , we show that it is possible to design the strength of the defects so to balance the velocity detunings and to allow the resonant transmission through a larger number of defects . the possibility of using these results for very precise gap - soliton dynamical filters is suggested . .
And you have already written the first three sentences of the full article: bose - einstein condensates ( becs ) in optical lattices ( ols ) are presently attracting a great deal of interest @xcite due both to their flexibility in parameter design and to the possibility they offer to observe interesting phenomena such as superfluid to mott - insulator transition @xcite , bloch oscillations @xcite , landau - zener tunneling @xcite , generation of coherent atomic pulses ( atom laser ) @xcite , atom interferometry @xcite , etc . in this respect , ols allow to control important properties of bec by means of their periodic structure , this allowing , for example , the existence and stability of localized nonlinear excitations with chemical potentials inside band - gaps ( so called gap - solitons ( gss ) ) even in the presence of repulsive interactions ( positive scattering lengths ) .
this fact , that would be obviously impossible in absence of the ol @xcite , has been experimentally demonstrated in @xcite .
modulations of the ol can be used to accelerate , decelerate or to scatter gss as well as to control their velocities @xcite ..
Please generate the next two sentences of the article | uniform accelerations of the ol combined with periodic modulations of the scattering length , either in space or in time , were shown to be effective tools to induce long lived bloch oscillations in the nonlinear regime @xcite , as well as band - gap tunneling phenomena such as the landau - zener tunneling @xcite .
periodic time dependent ol accelerations were also used to achieve the dynamical localization of nonlinear matter waves @xcite and the rabi - oscillations of gs states across a band - gaps @xcite which survive on a long time scale in the presence of nonlinearity . |
6,085 | Suppose that you have an abstract for a scientific paper: in previous analyses of the oklo ( gabon ) natural reactor to test for a possible time variation of the fine - structure constant @xmath0 , a maxwell - boltzmann low energy neutron spectrum was assumed .
we present here an analysis where a more realistic spectrum is employed and show that the most recent isotopic analysis of samples implies a decrease in @xmath0 , over the last two billion years since the reactor was operating , of @xmath1 ( @xmath2 confidence ) .
issues regarding the interpretation of the shifts of the low energy neutron absorption resonances are discussed . .
And you have already written the first three sentences of the full article: it was recognized by shlyakhter @xcite that isotopic ratios of fission products and secondary neutron absorption reactions that occurred with the oklo natural reactor phenomenon some 2 billion years ago could be used to test whether the fine - structure constant @xmath0 varies with time .
specifically , if a neutron absorber ( e.g. , @xmath3sm ) has a low - energy neutron absorption resonance , and the excited compound state can decay by gamma emission , the resonance energy will change in a predictable way if @xmath0 varies . the overlap of the resonance with the reactor neutron spectrum will subsequently change thereby altering the ratios of nearby isotopes .
in addition to @xcite , two other detailed analyses of the oklo phenomenon have been completed @xcite ..
Please generate the next two sentences of the article | the purpose of this note is to assess the validity of the assumption in these analyses that the neutron spectrum can be described by a maxwell - boltzmann ( mb ) distribution , and to determine the effects on the limit of the time variation of @xmath0 for different neutron spectra .
the possibility of a non - mb spectrum was discussed in @xcite ( footnote 3 ) , but was not considered to be important . however , for the high - accuracy results presented in @xcite , the effects due to deviations from a mb spectrum become very important . |
6,086 | Suppose that you have an abstract for a scientific paper: during the period july 2007 - january 2009 , the agile satellite , together with several other space- and ground - based observatories monitored the activity of the flat - spectrum radio quasar 3c 454.3 , yielding the longest multiwavelength coverage of this quasar so far .
the source underwent an unprecedented period of very high activity above 100 mev , a few times reaching flux levels on a day time scale higher than @xmath0 , in conjunction with an extremely variable behavior in the optical @xmath1-band , even of the order of several tenth of magnitude in few hours , as shown by the gasp - webt light curves .
we present the results of this long term multiwavelength monitoring campaign , with particular emphasis on the study of possible lags between the different wavebands , and the results of the modeling of simultaneous spectral energy distributions at different levels of activity . .
And you have already written the first three sentences of the full article: among active galactic nuclei ( agns ) , blazars show intense and variable emission above 100 mev @xcite , and the variability time scale can be as short as a few days , or last a few weeks .
they emit across several decades of energy , from the radio to the tev energy band and their spectral energy distributions ( seds ) are typically double humped with a first peak occurring in the ir / optical band in the flat - spectrum radio quasars ( fsrqs ) and low - energy peaked bl lacs ( lbls ) , and at uv / x - rays in the high - energy peaked bl lacs ( hbls ) .
this peak is commonly interpreted as synchrotron radiation from high - energy electrons in a relativistic jet ..
Please generate the next two sentences of the article | the second sed component is commonly interpreted as inverse compton ( ic ) scattering of soft seed photons by relativistic electrons , and peaks in the mev gev and in the tev energy bands in the fsrqs / lbls and in the hbls , respectively .
a recent review of the blazar emission mechanisms and energetics is given in @xcite . |
6,087 | Suppose that you have an abstract for a scientific paper: fault tolerance is achieved through multiply redundant hardware systems in large civil aircraft .
this means of achieving fault tolerance is infeasible for small compact unmanned aerial vehicles . in this paper
we apply a fault tolerant control system which exploits analytical redundancy rather than hardware redundancy to an actual uav model currently in operation via model - in - the - loop simulation .
the fault tolerant control system comprises a nonlinear model predictive controller integrated with an unscented kalman filter for fault detection and identification .
the results show that our fault tolerant control system design is able to identify engine failure within seconds of fault occurrence and distribute control authority to the healthy actuators to maintain safe flight . .
And you have already written the first three sentences of the full article: [ cols="<,^ , < " , ] trim conditions for the aircraft at 20 m/s are : @xmath0 , @xmath1 and @xmath2 and have been used as initial conditions for the controller . again a prediction window of 5 seconds along with 50 coincidence points were used . the upper limit on the thrust constraint continually changes based on the true airspeed of the aircraft according to the equations given in . the minimum thrust level set always to @xmath3 . if however an engine failure
is detected the upper limit on thrust is set to the filter estimate plus @xmath4 uncertainty . +
a ukf filter was designed to perform fdi with the following process noise and noise covariance matrices : @xmath5 where @xmath6 is the filter update rate 0.01 secs ..
Please generate the next two sentences of the article | the initial state vector and covariance matrix are : @xmath7^\intercal , \quad \mathbf{p}(0 ) = \begin{bmatrix } ( 0.5)^2 & 0 & 0 & 0\\ 0 & ( 0.5)^2 & 0 & 0\\ 0 & 0 & ( 0.0850)^2 & 0\\ 0 & 0 & 0 & ( 6)^2 \end{bmatrix}.\ ] ] finally the fault detection logic is based on that given in @xcite . the following scenarios were set up to test the active ftc system on the uav model : 1 .
no fault case 2 . |
6,088 | Suppose that you have an abstract for a scientific paper: we study the possible heavy molecular states composed of a pair of charm mesons in the h and s doublets . since the p - wave charm - strange mesons @xmath0 and
@xmath1 are extremely narrow , the future experimental observation of the possible heavy molecular states composed of @xmath2 and @xmath3 may be feasible if they really exist .
especially the possible @xmath4 states may be searched for via the initial state radiation technique . .
And you have already written the first three sentences of the full article: the new family of the charmonium or charmonium - like states include @xmath5 , @xmath6 , @xmath7 , @xmath8 , @xmath9 , @xmath10 , @xmath11 , @xmath12 , @xmath13 , @xmath14 and @xmath15 etc @xcite .
many states sit on the the threshold of two charmed mesons , which inspired some of them ( especially those charged ones ) to be candidates of heavy moleculues @xcite . in the heavy quark limit
, the s - wave and p - wave heavy mesons can be categorized into three doublets : @xmath16 , @xmath17 , @xmath18 ..
Please generate the next two sentences of the article | we collect their masses from pdg in table [ hs ] .
the bottom mesons in the @xmath19 doublet are still missing experimentally . |
6,089 | Suppose that you have an abstract for a scientific paper: information gain in communication is bounded by the information encoded in the physical systems exchanged between sender and receiver .
surprisingly , this does not hold for quantum entanglement , which can increase even though the communicated system carries no entanglement at all . here
we demonstrate this phenomenon in a four - photon experiment where two parties sharing initially separable ( unentangled ) state get entangled by exchanging a photon that is _ at all times _ not entangled with either of them .
our result validates a long - standing assert in quantum information and has important practical implications in quantum networking , where entanglement must be reliably distributed across many nodes at low resource - cost . .
And you have already written the first three sentences of the full article: communication is the exchange of physical systems aimed at establishing correlations between the communicating parties . in most circumstances we are interested in the total amount of correlations , _
i.e. _ the mutual information , between the sender and receiver @xcite .
information theory can thus be used to make statements governing any communication process @xcite ..
Please generate the next two sentences of the article | one of the most fundamental of them claims that the gain of information achieved by communicating parties can not exceed the amount of information that is actually transmitted @xcite . beside agreeing fully with everyday experience ,
this adheres well with the expectation that in a communication protocol no form of correlation can be established without transmitting that kind of correlation . |
6,090 | Suppose that you have an abstract for a scientific paper: the recently - developed non - equilibrium extension of the self - consistent generalized langevin equation theory of irreversible relaxation [ phys .
rev .
e ( 2010 ) * 82 * , 061503 ; ibid .
061504 ] is applied to the description of the irreversible process of equilibration and aging of a glass - forming soft - sphere liquid that follows a sudden temperature quench , within the constraint that the local mean particle density remains uniform and constant . for these particular conditions ,
this theory describes the non - equilibrium evolution of the static structure factor @xmath0 and of the dynamic properties , such as the self - intermediate scattering function @xmath1 , where @xmath2 is the correlation _ delay _
time and @xmath3 is the _ evolution _ or _ waiting _ time after the quench .
specific predictions are presented , for the deepest quench ( to zero temperature ) .
the predicted evolution of the @xmath4-relaxation time @xmath5 as a function of @xmath3 allows us to define the _ equilibration _ time @xmath6 , as the time after which @xmath5 has attained its equilibrium value @xmath7 .
it is predicted that both , @xmath6 and @xmath7 , diverge as @xmath8 , where @xmath9 is the hard - sphere dynamic - arrest volume fraction @xmath10 , thus suggesting that the measurement of _ equilibrium _ properties at and above @xmath9 is experimentally impossible .
the theory also predicts that for fixed finite waiting times @xmath3 , the plot of @xmath11 as a function of @xmath12 exhibits two regimes , corresponding to samples that have fully equilibrated within this waiting time @xmath13 , and to samples for which equilibration is not yet complete @xmath14 .
the crossover volume fraction @xmath15 increases with @xmath3 but saturates to the value @xmath9 . _ _ .
And you have already written the first three sentences of the full article: classical and statistical thermodynamics deal with the equilibrium states of matter @xcite . driving the system from one equilibrium state to another
, however , involves the passage of the system through a sequence of instantaneous states that do not satisfy the conditions for thermodynamic equilibrium , and hence , constitute a non - equilibrium process @xcite .
the description of these processes fall outside the realm of classical and statistical thermodynamics , unless the sequence of non - equilibrium states do not depart appreciably from a sequence of equilibrium states ..
Please generate the next two sentences of the article | such idealized process can be thought of as an infinite sequence of infinitesimally small changes in the driving control parameter , after each of which the system is given sufficient time to equilibrate .
this so - called quasistatic process is an excellent representation of real process when the equilibration times of the system are sufficiently short . |
6,091 | Suppose that you have an abstract for a scientific paper: realization of topological insulators ( tis ) and superconductors ( tscs ) , such as the quantum spin hall effect and the @xmath0 topological insulator , in terms of d - branes in string theory is proposed .
we establish a one - to - one correspondence between the k - theory classification of tis / tscs and d - brane charges .
the string theory realization of tis and tscs comes naturally with gauge interactions , and the wess - zumino term of the d - branes gives rise to a gauge field theory of topological nature .
this sheds light on tis and tscs beyond non - interacting systems , and the underlying topological field theory description thereof .
topological insulators and superconductors from d - brane + shinsei ryu@xmath1 and tadashi takayanagi@xmath2 .
And you have already written the first three sentences of the full article: a gapped state of quantum condensed matter is called topological phase when it supports stable gapless boundary modes , such as an edge or a surface state . the integer quantum hall effect
( qhe ) , which exists in @xmath3 spatial dimensions and under a strong magnetic field , is the best known example of such a phase .
the recent discovery of the quantum spin hall effect ( qshe ) in @xmath3 and the @xmath0 topological insulator in @xmath4 @xcite shows topological phases can exist even in @xmath5 spatial dimensions , and can be protected by some discrete symmetries such as time - reversal symmetry ( trs , t ) , particle - hole symmetry ( phs , c ) , and chiral ( or sublattice ) symmetry ( sls , s ) . for non - interacting fermions , an exhaustive classification of topological insulators ( tis ) and superconductors ( tscs ).
Please generate the next two sentences of the article | is proposed in refs .
@xcite : tis / tscs are classified in terms of spatial dimensions @xmath6 and the @xmath7 symmetry classes ( two `` complex '' and eight `` real '' classes ) ( table [ charge ] ) . |
6,092 | Suppose that you have an abstract for a scientific paper: we consider an anisotropically two - dimensional diffusion of a charged molecule ( particle ) through a large biological channel under an external voltage .
the channel is modeled as a cylinder of three structure parameters : radius , length , and surface density of negative charges located at the channel interior - lining .
these charges induce inside the channel a potential that plays a key role in controlling the particle current through the channel .
it was shown that to facilitate the transmembrane particle movement the channel should be reasonably self - optimized so that its potential coincides with the resonant one , resulting in a large particle current across the channel . observed facilitation appears to be an intrinsic property of biological channels , regardless the external voltage or the particle concentration gradient .
this facilitation is very selective in the sense that a channel of definite structure parameters can facilitate the transmembrane movement of only particles of proper valence at corresponding temperatures .
calculations also show that the modeled channel is non - ohmic with the ion conductance which exhibits a resonance at the same channel potential as that identified in the current . .
And you have already written the first three sentences of the full article: biological channels are responsible for regulating the fluxes of ions and molecules ( hereafter referred to as particles for short ) across membranes and , therefore , are critically important for the cell functioning @xcite . as well - known , these protein channels are very efficient in the sense that they support a very fast , selective , and robust across - membrane transport , regardless of environment fluctuations @xcite . surprisingly , such privileged properties have been observed even in the case of large water - filled channels , where the particle transport does not involve the use of metabolic energy or conformational changes and was assumed to be simply diffusive @xcite .
understanding the nature of this channel - facilitated particle movement ( cfpm ) is crucially important from the fundamental molecular biology as well as the application point of view ( many modern drugs are developed in the way of using the ion - channels to enhance their efficiency , see for example refs.@xcite ) . experimentally , there are accumulative data showing that the observed cfpm is really resulted from some interaction between the moving particle and the channel - interior lining @xcite
. recent advancements of high - resolution current recording enable single - channel measurements that provide directly a living picture of how an individual channel functions and , therefore , shed light on the characteristics of channel current in dependence on different ( channel and environment ) parameters @xcite ..
Please generate the next two sentences of the article | however , revealing exactly the nature of channel - particle interaction as well as the mechanism of cfpm is still very experimentally problemic due to the puzzled complexities related to both the channel structure and the measurement systems . theoretically , to describe the cfpm several models have been suggested .
considering the one - dimensional ( 1d ) diffusion model with a position - dependent diffusion coefficient , berezhkovskii et al . |
6,093 | Suppose that you have an abstract for a scientific paper: we present the first rigorous construction of the qft thirring model , for any value of the mass , in a functional integral approach , by proving that a set of grassmann integrals converges , as the cutoffs are removed , to a set of schwinger functions verifying the osterwalder - schrader axioms .
the massless limit is investigated and it is shown that the schwinger functions have different properties with respect to the ones of the well known exact solution : the ward identities have anomalies violating the anomaly non - renormalization property and additional anomalies , apparently unnoticed before , are present in the closed equation for the interacting propagator , obtained by combining a schwinger - dyson equation with ward identities . .
And you have already written the first three sentences of the full article: the thirring model has been the subject of a very intense research in the last fifty years : it is one of the very few qft models for which non - perturbative informations can be obtained and it shares with more realistic @xmath0 models , like @xmath1 , many features , as it is apparent from a classical perturbative feynman graph analysis @xcite . in the _ massless case _ ,
a complete set of correlations has been obtained via an exact solution @xcite ; they verify the wightman recontruction axioms @xcite so that a qft corresponding to the massless thirring model can be constructed from them . in the _ massive case _ , the equivalence ( at a perturbative level ) with the sine - gordon model is known @xcite and some eigenstates by bethe - ansatz analysis have been found @xcite ; but a complete rigorous construction has never been performed . in this paper
we fill this gap by considering a set of grassmann integrals regularized via suitable cutoffs and with a contact current - current interaction and proving that , removing cutoffs and for any value of the mass , they converge to a set of schwinger functions verifying the osterwalder - schrader reconstruction axioms for euclidean qft @xcite ; this provides the first rigorous construction of the massive thirring model ..
Please generate the next two sentences of the article | moreover , even if in the massless case other constructions were known , we find in any case interesting to reach a complete non - perturbative construction of the thirring model relying only on a functional integral approach , which could be the only possible one at higher dimensions or for more realistic models .
we stress that our results are _ non - perturbative _ , in the sense that the grassmann integrals are expressed in terms of series expansion whose _ convergence is proved _ ( that is we resum the naive perturbation theory and we prove the convergence of the resummed expansion ) . |
6,094 | Suppose that you have an abstract for a scientific paper: we present an exact static , spherically symmetric black hole solution to the third order lovelock gravity with a string cloud background in seven dimensions for the special case when the second and third order lovelock coefficients are related via @xmath0 .
further , we examine thermodynamic properties of this black hole to obtain exact expressions for mass , temperature , entropy and also perform the thermodynamic stability analysis .
we see that a string cloud background makes a profound influence on horizon structure , thermodynamic properties and the stability of black holes .
interestingly the entropy of the black hole is unaffected due to a string cloud background .
however , the critical solution for thermodynamic stability is being affected by a string cloud background . .
And you have already written the first three sentences of the full article: black holes through quantum outcome indicate that they radiate due to the hawking effect @xcite . in the absence of established theories of quantum gravity ,
black holes have become a main playground to divulge quantum gravity effects through their thermodynamics .
black holes have been used as theorists laboratories in many other relevant fields ..
Please generate the next two sentences of the article | thermodynamic properties of black holes have been studied for many years , but established statistical explanations of black hole thermodynamics are still lacking .
it shows that black holes also have the standard thermodynamic quantities , such as temperature , entropy and heat capacity and so on , and even possess abundant phase structures like the hawking - page phase transition @xcite and similar critical phenomena in ordinary thermodynamic systems . |
6,095 | Suppose that you have an abstract for a scientific paper: we present a combined group - theoretical and tight - binding approach to calculate the intrinsic spin - orbit coupling ( soc ) in abc stacked trilayer graphene .
we find that compared to monolayer graphene ( s. konschuh , m. gmitra , and j. fabian [ phys . rev .
b 82 , 245412 ( 2010)])@xcite , a larger set of @xmath0 orbitals ( in particular the @xmath1 orbital ) needs to be taken into account .
we also consider the intrinsic soc in bilayer graphene , because the comparison between our tight - binding bilayer results and the density functional computations of ( ref . allows us to estimate the values of the trilayer soc parameters as well .
we also discuss the situation when a substrate or adatoms induce strong soc in only one of the layers of bilayer or abc trilayer graphene . both for the case of intrinsic and externally induced soc
we derive effective hamiltonians which describe the low - energy spin - orbit physics .
we find that at the @xmath2 point of the brillouin zone the effect of bychkov - rashba type soc is suppressed in bilayer and abc trilayer graphene compared to monolayer graphene . .
And you have already written the first three sentences of the full article: the low - energy properties of multilayer graphene@xcite depend crucially on the stacking order of the constituent graphene layers@xcite . in the case of trilayer graphene , there are two stable stacking orders : ( i ) aba or bernard stacking and ( ii ) abc or chiral stacking . recent advances in sample fabrication methods have resulted in high - quality trilayer samples which can be used to probe many of the theoretical predictions@xcite .
abc stacked trilayer graphene appears to be particularly exciting because it is expected to host a wealth of interesting phenomena , such as chiral quasiparticles with berry phase @xmath3@xcite , a lifshitz transition of electronic bands due to trigonal warping@xcite , band - gap opening in an external electric field@xcite , and broken symmetry phases at low electron densities@xcite , to name a few .
although there are a number of theoretical@xcite and experimental@xcite studies on the electronic properties of aba and abc stacked trilayer graphene , the spin - orbit coupling ( soc ) in these systems has received much less attention ..
Please generate the next two sentences of the article | aba trilayer graphene was considered in ref . within a framework of an effective low - energy theory , whereas the case abc stacking was only briefly mentioned in ref . .
the understanding of spin - orbit interaction would be important to study other interesting and experimentally relevant phenomena such as spin relaxation@xcite , weak - localization@xcite or even spin - hall effect@xcite in trilayer graphene . |
6,096 | Suppose that you have an abstract for a scientific paper: the magnetic response of a proximity - coupled superconductor - normal metal sandwich is studied within the framework of the quasiclassical theory .
the magnetization is evaluated for finite values of the applied magnetic field ( linear and nonlinear response ) at arbitrary temperatures and is used to fit recent experimental low - temperature data .
the hysteretic behavior predicted from a ginzburg - landau approach and observed in experiments is obtained within the quasiclassical theory and shown to exist also outside the ginzburg - landau region . .
And you have already written the first three sentences of the full article: a superconductor in electric contact with a normal metal induces superconducting correlations on the normal side .
this _ proximity effect _ has been studied extensively , both theoretically and experimentally ( see ref . and references therein ) .
the superconducting properties of the normal metal show up , e.g. , in the conductance or the magnetization ( meissner effect ) ..
Please generate the next two sentences of the article | the vanishing of the resistance of a normal wire in contact to superconducting islands has been observed . in recent experiments ( typically with wires consisting of a superconducting core covered by a normal metal ) by oda and nagano @xcite , mota _ et al . _
@xcite , and bergmann _ et al . |
6,097 | Suppose that you have an abstract for a scientific paper: we study the signals for a `` fermiophobic '' charged higgs boson present in an extension of the standard model with an additional higgs doublet and right handed neutrinos , responsible for generating dirac - type neutrino masses .
we study the pair production of the charged higgs at the large hadron collider ( lhc ) , which can be relatively light and still allowed by experimental data .
the charged higgs decays dominantly into a @xmath0 boson and a very light neutral scalar present in the model , which decays invisibly and passes undetected .
we find that the signal for such a charged higgs is overwhelmed by the standard model background and will prove elusive at the 8 tev run of the lhc .
we present a cut - flow based analysis to pinpoint a search strategy at the 14 tev run of the lhc which can achieve a signal significance of 5@xmath1 for a given mass range of the charged higgs . .
And you have already written the first three sentences of the full article: the search for new physics beyond the standard model is continuing at the large hadron collider ( lhc ) .
although we are yet to see any clear hint , there is reason for exhilaration in another way , namely , the discovery of a boson of mass @xmath2 125 gev @xcite . the properties of this particle are very similar to the higgs boson predicted in the standard model ( sm ) , but possibilities of some new physics information contained in it can not yet be ruled out .
thus a great deal of attention has shifted to the exploration of physics beyond the standard model ( bsm ) in the electroweak symmetry breaking sector ..
Please generate the next two sentences of the article | one vexing issue , often mentioned as a motivation for bsm physics , is the identification of a mechanism for neutrino mass generation .
this basically means finding some explanation for the smallness of neutrino masses as compared to those for the other fermions , and also the very different nature of mixing evinced in the neutrino ( or more precisely , lepton ) sector @xcite . |
6,098 | Suppose that you have an abstract for a scientific paper: we quantify the slow - roll corrections to primordial density perturbations arising from inflation driven by a four - dimensional scalar field with a monomial potential in a five - dimensional non - compact bulk spacetime .
although the difference between the classical brane - world solutions and standard four - dimensional solutions is large at early times , the change to the amplitude at late times of perturbations generated from quantum fluctuations is first - order in slow - roll parameters , leading to second - order slow - roll corrections to the spectral index .
this confirms that the leading - order effects are correctly given by previous work in the literature . .
And you have already written the first three sentences of the full article: recent proposals in theoretical physics have suggested that our four - dimensional universe could lie on a brane embedded in a higher - dimensional space - time @xcite .
one of the most studied is the randall sundrum ( rs ) model @xcite where our four - dimensional universe is a brane embedded in five - dimensional anti - de sitter space - time ( ads@xmath0 ) .
indeed it is possible in this framework to have only one brane in a non - compact space and this is the scenario we will consider in this letter ..
Please generate the next two sentences of the article | this brane - world perspective may dramatically change our picture of the early universe . in this model , the friedmann equation
is modified @xcite to @xmath1 so that the hubble parameter @xmath2 at high energy - density . |
6,099 | Suppose that you have an abstract for a scientific paper: a magnetohydrodynamic model is constructed for a cylindrical jet immersed in an external uniform magnetic field .
it is shown that , as in the force - free case , the total electric current within the jet can be zero .
the particle energetics and the magnetic field structure are determined in a self - consistent way ; all jet parameters depend on the physical conditions in the external medium .
in particular , we show that a region with subsonic flow can exist in the central jet regions . in actual relativistic jets ,
most of the energy is transferred by the electromagnetic field only when the magnetization parameter is sufficiently large , @xmath0 .
we also show that , in general , the well - known solution with a central core , @xmath1 , can not be realized in the presence of an external medium
. = -2.0 cm = -3.0 cm = 17.5 cm .
And you have already written the first three sentences of the full article: the formation mechanism of jets is a key issue in the study of the magnetospheric structure of compact astrophysical objects .
indeed , jets are observed in most compact sources , ranging from active galactic nuclei ( agns ) , quasars , and radio galaxies @xcite to accreting neutron stars , solar - mass black holes ( ss 433 , x - ray novae ) @xcite , and young stellar objects @xcite .
moreover , jets have also been recently discovered in young radio pulsars @xcite . at the same time , in most studies devoted to the magnetohydrodynamic ( mhd ) model of such objects @xcite , in which the formation of jets is coupled with the attraction of longitudinal currents flowing in the magnetosphere , the attention was focused on intrinsic collimation in the sense that the effect of the external medium was assumed to be marginal ..
Please generate the next two sentences of the article | however , such a situation is possible only for a nonzero total current @xmath2 flowing within the jet @xcite , so the question of its closure in the outer parts of the magnetosphere arises . on the other hand , the longitudinal current
is often constrained by the regularity condition at the fast magnetosonic surface , which by no means always leads to the sufficiently large longitudinal currents required for collimation @xcite . in other words , with the exception of the force - free case @xcite , as yet no working model of a jet in which , on the one hand , the total electric current would be zero and , on the other hand , the total magnetic flux @xmath3 in the jet would be finite , has been constructed . |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.