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10,500 |
Suppose that you have an abstract for a scientific paper: in the theory of resonant scattering , the double differential cross section involves the computation of a multifold integral of a 4-point correlation function , which generalizes the traditional 2-point correlation function of van - hove for potential scattering . in the case of a neutron - crystal interaction , the numerical computation of these multifold integrals
is cumbersome . in this paper ,
a new approximation is suggested .
it is based on a factorization of the differential cross section into one function describing the exchange of kinetic energy between the neutron and the bound nucleus ( phonons dynamic ) and a function related to the nuclear scattering amplitude .
this formalism is then applied to the modeling of resonant scattering of a neutron by @xmath0 in a @xmath1 crystal lattice . .
And you have already written the first three sentences of the full article: the computation of the double differential scattering cross section ( ddcs ) at low incident neutron energies is required to solve neutron transport problems .
wigner and wilkins @xcite used a two - body kinematic approach to study potential scattering in a free gas . under the same classic assumptions , blackshaw and murray @xcite studied the case of an energy - dependent cross section and
further generalizations were investigated by ouisloumen and sanchez @xcite and rothenstein and dagan @xcite . a general quantum formalism due primarily to van hove @xcite expresses the ddcs of potential scattering by a bound nucleus as a fourier transform of a 2-point correlation function ..
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kazarnovski et al .
@xcite and word and trammell @xcite extended the van hove theory to study resonant processes .
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10,501 |
Suppose that you have an abstract for a scientific paper: we investigate the 21 cm signals from the uv ionizing sources in the reionization epoch .
the formation and evolution of 21 cm emission and absorption regions depend essentially on the kinetics of photons in the physical and frequency spaces . to solve the radiative transfer equation
, we use the weno algorithm , which is effective to capture the sharp ionization profile and the cut - off at the front of light @xmath0 and to handle the small fraction of neutral hydrogen and helium in the ionized sphere .
we show that a spherical shell of 21 cm emission and absorption will develop around a point source once the speed of the ionization front ( i - front ) is significantly lower than the speed of light .
the 21 cm shell extends from the i - front to the front of light ; its inner part is the emission region and its outer part is the absorption region .
the 21 cm emission region depends strongly on the intensity , frequency - spectrum and life - time of the uv ionizing source . at redshift @xmath1 , for a uv ionizing source with an intensity @xmath2 and a power law spectrum @xmath3 with @xmath4 ,
the emission region has a comoving size of 1 - 3 mpc at time @xmath5 myr .
nevertheless , the emission regions are very small , and would be erased by thermal broadening if the intensity is less than @xmath6 , the frequency spectrum is thermal at temperature @xmath7 k , or the frequency spectrum is a power law with @xmath8 . on the other hand ,
the 21 cm absorption regions are developed in all these cases . for a source of short life - time
, no 21 cm emission region can be formed if the source dies out before the i - front speed is significantly lower than the speed of light . yet , a 21 cm absorption region can form and develop even after the emission of the source ceases . .
And you have already written the first three sentences of the full article: the detection of redshifted 21 cm signals from the early universe is attracting many attentions in the study of cosmology , because it provides a window to probe the baryonic gas and the first generation of light sources in the cosmic dark ages ( e.g. furlanetto et al .
observational projects of highly sensitive meter radio telescopes , such as the low frequency array ( lofar ) ( rottgering 2003 ) , the square kilometer array ( ska ) ( van de weygaert & van albada 1996 ) , the mileura widefield array ( mwa ) and the 21 cm array ( 21cma ) ( pen et al .
2004 ) , are ongoing or being planned ..
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a major challenge to detect the primordial 21 cm signals is from the contamination of radio signals of the foreground .
the brightness temperature fluctuations of the 21 cm signals would be seriously contaminated by high - redshift radio point sources , free - free emissions of the igm , and the noises from the artificial radio interference in the vhf band ( di matteo et al .
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10,502 |
Suppose that you have an abstract for a scientific paper: fix a sequence of integers @xmath0 such that @xmath1 is greater than or equal to @xmath2 for all @xmath3 . in this paper , we improve upon results by j. galambos and f. schweiger showing that almost every ( in the sense of lebesgue measure ) real number in @xmath4 is @xmath5-normal with respect to the @xmath5-cantor series expansion for sequences @xmath5 that satisfy a certain condition .
we also provide asymptotics describing the number of occurrences of blocks of digits in the @xmath5-cantor series expansion of a typical number . the notion of strong @xmath5-normality , that satisfies a similar typicality result ,
is introduced .
both of these notions are equivalent for the @xmath6-ary expansion , but strong normality is stronger than normality for the cantor series expansion . in order to show this , we provide an explicit construction of a sequence @xmath5 and a real number that is @xmath5-normal , but not strongly @xmath5-normal .
we use the results in this paper to show that under a mild condition on the sequence @xmath5 , a set satisfying a weaker notion of normality , studied by a. rnyi in @xcite , will be dense in @xmath4 . .
And you have already written the first three sentences of the full article: [ definition:1.1 ] let @xmath6 and @xmath7 be positive integers .
a _ block of length @xmath7 in base @xmath6 _ is an ordered @xmath7-tuple of integers in @xmath8 .
a _ block of length @xmath7 _ is a block of length @xmath7 in some base @xmath6 ..
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block _ is a block of length @xmath7 in base @xmath6 for some integers @xmath7 and @xmath6 .
[ definition:1.2 ] given an integer @xmath9 , the _ @xmath6-ary expansion _ of a real @xmath10 in @xmath4 is the ( unique ) expansion of the form @xmath11 such that @xmath12 is in @xmath8 for all @xmath3 with @xmath13 infinitely often .
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10,503 |
Suppose that you have an abstract for a scientific paper: the solar tower atmospheric cherenkov effect experiment ( stacee ) is designed to explore the gamma - ray sky between 20 and 250 gev using the atmospheric cherenkov technique .
stacee will use large solar heliostat mirrors to reflect cherenkov light created in gamma - ray air showers to secondary mirrors on a central tower .
the secondary mirrors image this light onto photomultiplier tube cameras that are read out by fast electronics . here
we outline the important features of the stacee design .
we present an overview of the experimental site , describe the method of heliostat selection and control , and discuss the current designs for the detector components , including the secondary mirror structures , cameras , and electronics . *
the stacee project + * ren ' e a. ong and corbin e. covault + _ enrico fermi institute , university of chicago , chicago , il 60637 , usa + _ ( for the stacee collaboration ) to appear in proc .
towards a major atmospheric cherenkov detector - v ( kruger park ) .
And you have already written the first three sentences of the full article: there is a window in the gamma - ray spectrum which has yet to be systematically explored by any telescope .
current state - of - the - art atmospheric cherenkov telescopes have energy thresholds of 250 gev or greater .
conversely , the egret experiment on the compton gamma ray observatory detects few astrophysical photons above 20 gev ..
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exploring the gamma - ray window between 20 and 250 gev is a primary goal of stacee .
a more complete discussion of the scientific motivation for exploring this window can be found elsewhere ( ong 1997 ) .
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10,504 |
Suppose that you have an abstract for a scientific paper: the remarkable rotational symmetry of the photosynthetic antenna complexes of purple bacteria has long been thought to enhance their light harvesting and excitation energy transport .
we study the role of symmetry by modeling hypothetical antennas whose symmetry is broken by altering the orientations of the bacteriochlorophyll pigments .
we find that in both lh2 and lh1 complexes , symmetry increases energy transfer rates by enabling the cooperative , coherent process of supertransfer .
the enhancement is particularly pronounced in the lh1 complex , whose natural geometry outperforms the average randomized geometry by 5.5 standard deviations , the most significant coherence - related enhancement found in a photosynthetic complex .
photosynthetic organisms use light - harvesting antenna complexes to absorb light and funnel the resulting excitation energy into a reaction center ( rc ) , where the energy is used to drive charge separation @xcite . despite the diversity of antenna complexes , the efficiency of excitation energy transfer ( eet @xcite ) through them is generally high , prompting hopes that understanding eet mechanisms in these complexes will generate new ideas for improving artificial light harvesting @xcite . in searching for design principles in photosynthetic architectures ,
it is important to not assume that a particular photosynthetic system is optimized simply because it is a product of billions of years of natural selection . if nothing else , the dramatically different antenna architectures in different plant and bacterial taxa @xcite can not all be optimal . in other words , the optimality of photosynthetic light harvesting is a hypothesis to be tested , with there being a distinct possibility that a particular arrangement is not optimal but is merely good enough to ensure the particular organism s survival .
a way to determine whether an eet architecture is optimal is to examine its performance if its structure is changed in significant ways @xcite .
this kind....
And you have already written the first three sentences of the full article: we consider the photosynthetic apparatus of the purple bacterium _ rhodobacter sphaeroides _ using the model described previously @xcite . as shown in fig .
[ fig : structure ] , it includes antenna complexes lh1 and lh2 that increase the amount of light absorbed per rc .
two rcs are surrounded by the s - shaped lh1 complex consisting of @xmath0 tightly packed bchls , which is itself surrounded by lh2 complexes , the structures being taken from crystal structures @xcite ..
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although each lh2 contains two rings of bchls , b800 and b850 , we only consider the 18-member b850 because eet between b800 and b850 is fast and efficient .
overall , the main inter - complex eet pathway is lh2 @xmath1 lh1 @xmath1 rc .
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10,505 |
Suppose that you have an abstract for a scientific paper: in june 2013 , brazil faced the largest and most significant mass protests in a generation .
these were exacerbated by the population s disenchantment towards its highly fragmented party system , which is composed by a very large number of political parties . under these circumstances ,
presidents are constrained by informal coalition governments , bringing very harmful consequences to the country . in this work
i propose _ arrange _ , a _
d**a**ta d**r**iven method fo**r * * * * a**ssessing and reduci**ng * * party fragm**e**ntation_in a country .
_ arrange_uses as input the roll call data for congress votes on bills and amendments as a proxy for political preferences and ideology . with that , _ arrange_finds the minimum number of parties required to house all congressmen without decreasing party discipline . when applied to brazil s historical roll call data , _
arrange_was able to generate distinct configurations that , compared with the _ status quo _ , have ( i ) a significant smaller number of parties , ( ii ) a higher discipline of partisans towards their parties and ( iii ) a more even distribution of partisans into parties . _ arrange_is fast and parsimonious , relying on a single , intuitive parameter . .
And you have already written the first three sentences of the full article: in june 2013 , brazil faced the largest and most significant mass protests in a generation , comparable in size to the protests that triggered the collapse of the military dictatorship in 1984 @xcite .
the 2013 protests had been exacerbated by the broader disenchantment of the population towards the party system in brazil @xcite .
banners with sentences such as `` no party represents me '' or `` we do nt have a party , we are brazil ! ''.
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were commonly seen among the protesters . in response to these protests ,
the government proposed a program of political reform @xcite .
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10,506 |
Suppose that you have an abstract for a scientific paper: we investigate the problem of shaping radially symmetric annular beams into desired intensity patterns along the optical axis . within the fresnel approximation ,
we show that this problem can be expressed in a variational form equivalent to the one arising in phase retrieval . using the uncertainty principle
we prove various rigorous lower bounds on the functional ; these lower bounds estimate the @xmath0 error for the beam shaping problem in terms of the design parameters .
we also use the method of stationary phase to construct a natural _ ansatz _ for a minimizer in the short wavelength limit .
we illustrate the implications of our results by applying the method of stationary phase coupled with the gerchberg - saxton algorithm to beam shaping problems arising in the remote delivery of beams and pulses .
beam shaping ; localized waves ; phase retrieval ; paraxial wave equation ; fresnel approximation .
And you have already written the first three sentences of the full article: in many applications it is desirable to shape a beam or pulse of light so that it has specific properties along the optical axis . in particular , for applications in microscopic imaging @xcite , optical tweezers @xcite , laser micro - machining @xcite , dressing of optical filaments @xcite , filament formation @xcite and long - range laser ablation @xcite , to name a few , it is important to have a well controlled beam with a nearly uniform intensity along the optical axis .
however , due to their wave nature localized packets of light will broaden spatially through diffraction .
for example , gaussian beams of width @xmath1 and wavenumber @xmath2 double in spatial extent over the rayleigh range @xmath3 @xcite . in a linear , isotropic medium the electric field of a beam of light polarized in the @xmath4 direction can be modeled by a wave packet of the form @xmath5 , where @xmath6 denotes the spatial coordinate along the optical axis , @xmath7 are the cartesian coordinates transverse to the optical axis , @xmath8 is time and @xmath9 the carrier angular frequency of the wave . within the slowly varying _ ansatz _ on @xmath10 , the propagation of a beam with initial data @xmath11 at the @xmath12 plane.
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is described by the paraxial wave equation : @xmath13 where @xmath14 is the transverse laplacian defined by @xmath15 @xcite .
exact solutions to equation ( [ intro : governingequation ] ) can be expressed in terms of an integral transform of the initial profile @xmath16 ; see [ appendix : solution ] .
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10,507 |
Suppose that you have an abstract for a scientific paper: we demonstrate magic wavelengths , at which external electric field produces null differential stark shifts , for the @xmath0 transitions in the cs atom due to circularly polarized light .
in addition , we also obtain magic wavelengths using linearly polarized light , in order to verify the previously reported values , and make a comparative study with the values obtained for circularly polarized light .
a number of these wavelengths are found to be in the optical region and could be of immense interest to experimentalists for carrying out high precision measurements . to obtain these wavelengths ,
we have calculated dynamic dipole polarizabilities of the ground , @xmath1 and @xmath2 states of cs .
we use the available precise values of the electric dipole ( e1 ) matrix elements of the transitions that give the dominant contributions from the lifetime measurements of the excited states .
other significantly contributing e1 matrix elements are obtained by employing a relativistic coupled - cluster singles and doubles method .
the accuracies of the dynamic polarizabilities are substantiated by comparing the static polarizability values with the corresponding experimental results . .
And you have already written the first three sentences of the full article: techniques involving laser cooling and trapping of neutral atoms are of immense interest for many scientific applications , including those that are capable of probing new physics @xcite and searching for exotic quantum phase transitions using ultracold atoms @xcite . in particular , trapping atoms using optical lattices have many advantages since they offer long storage time @xcite and their energy levels can be easily accessed using lasers @xcite .
it is conducive to carry out measurements in a transition of an optically trapped atom without realizing the stark shifts due to the applied laser field .
one can achieve this by trapping the atom at the wavelengths for which the differential stark shift of the transition gets nullified ..
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these wavelengths are popularly known as magic wavelengths ( @xmath3s ) @xcite .
they play crucial role in state - insensitive quantum engineering to set - up many high precision experiments .
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10,508 |
Suppose that you have an abstract for a scientific paper: chiral phase properties of finite size hadronic systems are investigated within the nambu jona - lasinio model .
finite size effects are taken into account by making use of the multiple reflection expansion .
we find that , for droplets with relatively small baryon numbers , chiral symmetry restoration is enhanced by the finite size effects .
however the radius of the stable droplet does not change much , as compared to that without the multiple reflection expansion . .
And you have already written the first three sentences of the full article: the behavior of ( finite lumps of ) quark matter is of great interests in cosmology , neutron stars , cosmic ray physics and heavy ion collisions @xcite .
absolutely stable nonstrange quark matter contradicts ordinary nuclei consisting of neutrons and protons .
however , the existence of stable strange quark matter is still an open question and it may be realized in the form of strangelets , small lumps of strange quark matter ..
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the ( meta)stability of nonstrange and strange quark matter has been investigated within the mit bag model @xcite , quark mass density dependent model @xcite , nambu jona - lasinio ( njl ) model @xcite , and so on @xcite . in the mit bag model , which assumes that asymptotically free quarks are confined in a bag , the bag constant and the current quark masses are phenomenological input parameters .
farhi and jaffe @xcite found a reasonable range of these parameters in which strange quark matter is stable , while nonstrange quark matter is unstable as compared to a gas of @xmath0 .
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10,509 |
Suppose that you have an abstract for a scientific paper: anomaly mediation is a popular and well motivated supersymmetry breaking scenario .
different possible detailed realisations of this set - up are studied and actively searched for at colliders .
apart from limits coming from flavour , low energy physics and direct collider searches , these models are usually constrained by the requirement of reproducing the observations on dark matter density in the universe .
we reanalyse these bounds and in particular we focus on the dark matter bounds both considering the standard cosmological model and alternative cosmological scenarios .
these scenarios do not change the observable cosmology but relic dark matter density bounds strongly depend on them .
we consider few benchmark points excluded by standard cosmology dark matter bounds and suggest that loosening the dark matter constraints is necessary in order to avoid a too strong ( cosmological ) model dependence in the limits that are obtained for these models .
we also discuss briefly the implications for phenomenology and in particular at the large hadron collider .
cern - ph - th-2011 - 052 + lycen 2011 - 01 * anomaly mediated susy breaking scenarios in the light of cosmology and in the dark ( matter ) * a. arbey@xmath0 , a. deandrea@xmath1 and a. tarhini@xmath1 + _ @xmath2 universit de lyon , france ; universit lyon 1 , cnrs / in2p3 , umr5822 ipnl , f-69622 villeurbanne cedex , france _ + + + .
And you have already written the first three sentences of the full article: the search for supersymmetry and its breaking , in addition to the direct searches at lep , b - factories , tevatron and the large hadron collider ( lhc ) , is actively pursued using the wmap limits on the relic density constraints . however the sensitivity of the lightest supersymmetric particle relic density calculation to the variation of the cosmological expansion rate before big - bang nucleosynthesis ( bbn ) , even if modest and with no consequences on the cosmological observations , can modify considerably the relic density , and therefore change the constraints on the supersymmetric parameter space @xcite . in the standard cosmology
the dominant component before bbn is radiation , however energy density and entropy content can be modified . in the following
we consider the impact of different scenarios of alternative cosmologies ..
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the precision of the wmap data should therefore not make us forget the hypothesis which are implied by the use of standard cosmology .
we discuss in the following the implications of precision b - physics , direct searches and cold dark matter relic abundance for the case of anomaly mediated models , from a minimal anomaly mediation supersymmetry breaking @xcite , to mixed moduli - anomaly mediated @xcite and to hypercharge anomaly mediation @xcite .
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10,510 |
Suppose that you have an abstract for a scientific paper: we show that the problem of deciding whether a polygonal knot in a closed three - dimensional manifold bounds a surface of genus at most @xmath0 , is * np*-complete . we also show that the problem of deciding whether a curve in a pl manifold bounds a surface of area less than a given constant @xmath1 is * np*-hard . .
And you have already written the first three sentences of the full article: in this paper we investigate the computational complexity of some problems in three - dimensional topology and geometry .
we show that the problem of determining a bound on the genus of a knot in a 3-manifold , is * np*-complete . using similar ideas ,
we show that deciding whether a curve in a metrized pl 3-manifold bounds a surface of area less than a given constant @xmath1 is * np*-hard . determining whether a given knot is trivial or not is one of the historically central questions in topology ..
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the problem of finding an algorithm to determine knot triviality was posed by dehn @xcite .
dehn s investigations into this area led to the formulation of the word and isomorphism problems , which played an important role in the development of the theory of algorithms .
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10,511 |
Suppose that you have an abstract for a scientific paper: motivated by recent attempts to reconcile hints of direct dark matter detection by the cogent and dama experiments , we construct simple particle physics models that can accommodate the constraints .
we point out challenges for building reasonable models and identify the most promising scenarios for getting isospin violation and inelasticity , as indicated by some phenomenological studies . if inelastic scattering is demanded , we need two new light gauge bosons , one of which kinetically mixes with the standard model hypercharge and has mass @xmath0 gev , and another which couples to baryon number and has mass @xmath1 gev .
their interference gives the desired amount of isospin violation .
the dark matter is nearly dirac , but with small majorana masses induced by spontaneous symmetry breaking , so that the gauge boson couplings become exactly off - diagonal in the mass basis , and the small mass splitting needed for inelasticity is simultaneously produced .
if only elastic scattering is demanded , then an alternative model , with interference between the kinetically mixed gauge boson and a hidden sector scalar higgs , is adequate to give the required isospin violation . in both cases ,
the light kinetically mixed gauge boson is in the range of interest for currently running fixed target experiments . .
And you have already written the first three sentences of the full article: hints of direct detection of dark matter ( dm ) currently exist from two experiments .
there is a long - standing observation of an annual modulation in the signal observed by dama @xcite , whose statistical significance is beyond question .
last year the cogent experiment reported excess events in their lowest electron energy bins @xcite , followed more recently by a @xmath2 detection of annual modulation in the signal @xcite . under the simplest assumptions about the nature of the dark matter interactions ,.
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these two observations appear to be incompatible with each other @xcite and with upper limits obtained by other experiments , especially cdms @xcite , xenon10 @xcite and xenon100 @xcite .
channeling of recoiling ions along the crystal planes in the detectors has been suggested as one loophole for reconciling the conflicts , but this has been argued to be too small an effect by ref .
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10,512 |
Suppose that you have an abstract for a scientific paper: we present a detailed analysis of the exact numerical spectrum of up to ten interacting electrons in the first landau level on the disk geometry .
we study the edge excitations of the hierarchical plateaus and check the predictions of two relevant conformal field theories : the multi - component abelian theory and the @xmath0 minimal theory of the incompressible fluids .
we introduce two new criteria for identifying the edge excitations within the low - lying states : the plot of their density profiles and the study of their overlaps with the jain wave functions in a meaningful basis .
we find that the exact bulk and edge excitations are very well reproduced by the jain states ; these , in turn , can be described by the multi - component abelian conformal theory .
most notably , we observe that the edge excitations form sub - families of the low - lying states with a definite pattern , which is explained by the @xmath0 minimal conformal theory . actually , the two conformal theories are related by a projection mechanism whose effects are observed in the spectrum .
therefore , the edge excitations of the hierarchical hall states are consistently described by the @xmath0 minimal theory , within the finite - size limitations .
200 1 2_1 .
And you have already written the first three sentences of the full article: one of the important open problems in the physics of the quantum hall effect ( qhe ) @xcite@xcite is the complete understanding of the hierarchical hall plateaus , whose filling fractions fall beyond the laughlin sequence @xmath1 @xcite .
there are two kinds of theoretical descriptions available at present : the wave - function constructions and the effective conformal field theories ( cft ) in @xmath2 dimensions .
the first approach has culminated in the jain theory of the composite - fermion correspondence between the integer hall states with @xmath3 and the hierarchical states with @xmath4 , @xmath5 , such as @xmath6 @xcite ..
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the existence of the composite - fermion excitations has been confirmed by many experiments @xcite ; the corresponding ansatz wave - functions have been tested in numerical simulations of few electron systems @xcite@xcite@xcite .
these have been mostly done on the spatial geometry of the sphere and have firmly established that the jain states describe the bulk excitations of quantum hall fluids . on the other hand ,
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10,513 |
Suppose that you have an abstract for a scientific paper: we report the magnetic - field dependence of the irreversible magnetization of the recently discovered binary superconductor mgb@xmath0 . for the temperature region of @xmath1
, the contribution of the bulk pinning to the magnetization overwhelms that of the surface pinning .
this was evident from the fact that the magnetization curves , @xmath2 , were well described by the critical - state model without considering the reversible magnetization and the surface pinning effect .
it was also found that the @xmath2 curves at various temperatures scaled when the field and the magnetization were normalized by the characteristic scaling factors @xmath3 and @xmath4 , respectively .
this feature suggests that the pinning mechanism determining the hysteresis in @xmath2 is unique below @xmath5 . 2 .
And you have already written the first three sentences of the full article: in the mixed state , the magnetization of superconductors is a combination of two different contributions , @xmath6 and @xmath7 .
@xmath6 is the equilibrium ( or reversible ) magnetization@xcite and @xmath7 is the irreversible magnetization .
the former is caused by the equilibrium surface current ..
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the latter arises from the surface ( bean - livingston ) barrier effect,@xcite as well as the bulk pinning due to the interaction between vortices and various defects within the superconductor .
the surface barrier originates from the competition between two forces , ( a ) an attractive interaction between a vortex and its image vortex and ( b ) a repulsive interaction between a vortex and the surface shielding current . for high-@xmath8 cuprate superconductors , the irreversible magnetization at low temperatures
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10,514 |
Suppose that you have an abstract for a scientific paper: the spectrum of the recently discovered cataclysmic variable star ( cv ) 13cl shows that a secondary star with spectral type k4 ( @xmath0 2 subclasses ) contributes roughly half the optical light .
the radial velocities of the secondary are modulated on an orbital period @xmath1 hr with a velocity semiamplitude @xmath2 km s@xmath3 , and the light curve shows ellipsoidal variations and an apparent grazing eclipse . at this orbital period ,
the secondary stars in most cvs are substantially cooler , with spectral types near m3 .
13cl therefore joins the small group of cvs with anomalously warm secondary stars , which apparently form when the onset of mass transfer occurs after the secondary has undergone significant nuclear evolution . .
And you have already written the first three sentences of the full article: cataclysmic variable stars ( cvs ) are close binaries consisting of a white dwarf primary that accretes matter from a secondary star via roche lobe overflow .
the secondary is more extended than the white dwarf , and usually resembles a low - mass main - sequence star .
cvs have a rich phenomenology and have attracted a great deal of observational and theoretical interest ..
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@xcite gives a dated but useful review of these objects . because the secondary fills its roche lobe , its mean density is closely constrained by the orbital period , with the secondary s mean density being larger at shorter periods @xcite . on the main sequence ,
the mean density rises toward lower masses , so if the mass - radius relation of the secondary is similar to that of main - sequence stars , the orbital period gives a rough proxy measurement of the secondary s mass .
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10,515 |
Suppose that you have an abstract for a scientific paper: over decades , the time evolution of wigner functions along classical hamiltonian flows has been used for approximating key signatures of molecular quantum systems .
such approximations are for example the wigner phase space method , the linearized semiclassical initial value representation , or the statistical quasiclassical method .
the mathematical backbone of these approximations is egorov s theorem . in this paper , we reformulate the well - known second order correction to egorov s theorem as a system of ordinary differential equations and derive an algorithm with improved asymptotic accuracy for the computation of expectation values . for models with
easily evaluated higher order derivatives of the classical hamiltonian , the new algorithm s corrections are computationally less expensive than the leading order wigner method .
numerical test calculations for a two - dimensional torsional system confirm the theoretical accuracy and efficiency of the new method . [ section ] [ section ] [ section ] [ section ] [ section ] [ section ] .
And you have already written the first three sentences of the full article: molecular quantum systems are described by an unbounded self - adjoint operator , the schrdinger operator @xmath0 acting on the hilbert space of complex - valued square - integrable functions @xmath1 . here
, @xmath2 is a small positive parameter related to the inverse square root of the average nuclear mass , and @xmath3 is the nuclear potential function resulting from the born oppenheimer approximation , see @xcite .
the relevant time scales of nuclear quantum motion are of the order @xmath4 ..
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the time evolution of an initial wave function @xmath5 is governed by the time - dependent linear schrdinger equation @xmath6 with the appropriate @xmath7-scaling of the time - derivative or
equivalently by the action of the unitary evolution operator @xmath8 , since @xmath9 even though the schrdinger equation is a _ linear _ partial differential equation , the numerical simulation of physical quantities derived from the wave function @xmath10 is notoriously difficult for two reasons : the dimension @xmath11 of the nuclear configuration space is large . if a molecule consists of @xmath12 nuclei , then @xmath13 .
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10,516 |
Suppose that you have an abstract for a scientific paper: discretization of supersymmetric theories is an old problem in lattice field theory .
it has resisted solution until quite recently when new ideas drawn from orbifold constructions and topological field theory have been brought to bear on the question .
the result has been the creation of a new class of lattice gauge theory in which the lattice action is invariant under one or more supersymmetries .
the resultant theories are local and free of doublers and in the case of yang - mills theories also possess exact gauge invariance . in principle
they form the basis for a truly non - perturbative definition of the continuum supersymmetric field theory . in this talk
these ideas are reviewed with particular emphasis being placed on @xmath0 super yang - mills theory . .
And you have already written the first three sentences of the full article: the problem of formulating supersymmetric theories on lattices has a long history going back to the earliest days of lattice gauge theory .
however , after initial efforts failed to produce useful supersymmetric lattice actions the topic languished for many years . indeed a folklore developed that supersymmetry and the lattice were mutually incompatible . however , recently , the problem has been re - examined using new tools and ideas such as topological twisting , orbifold projection and deconstruction and a class of lattice models have been constructed which maintain one or more supersymmetries exactly at non - zero lattice spacing .
while in low dimensions there are many continuum supersymmetric theories that can be discretized this way , in four dimensions there appears to a unique solution to the constraints @xmath1 super yang - mills ..
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the availability of a supersymmetric lattice construction for this theory is clearly very exciting from the point of view of exploring the connection between gauge theories and string / gravitational theories .
but even without this connection to string theory it is clearly of great importance to be able to give a non - perturbative formulation of a supersymmetric theory via a lattice path integral in the same way that one can formally define qcd as a limit of lattice qcd as the lattice spacing goes to zero and the box size to infinity . from a practical point of view
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Suppose that you have an abstract for a scientific paper: a theory is developed for the evolution of the non - equilibrium distribution of quasiparticles when the scattering rate decreases due to particle collisions .
we propose a `` modified one - collision approximation '' which is most effective for high - energy quasiparticle distributions .
this method is used to explain novel measurements of the non - monotonic energy dependence of the signal of scattered electrons in a 2d system .
the observed effect is related to a crossover from the ballistic to the hydrodynamic regime of electron flow . .
And you have already written the first three sentences of the full article: the propagation of an electron beam in a two - dimensional degenerate electron gas ( 2deg ) can be used to study the role of electron - electron ( e - e ) collisions in reduced dimensions , see e.g. refs .
of main interest are `` high - energy '' beams with a typical electron energy that exceeds considerably the thermal energy of the equilibrium electrons within the 2deg , but remains significantly below the fermi energy .
a special combination of ac- and dc - measurement techniques allows for an energy selective investigation of electrons traversing a defined distance within a 2deg @xcite ..
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some of these experiments were analyzed in terms of the @xmath0-approximation @xcite , where it is supposed that each collision scatters an electron out of the beam .
however , this approach is obviously insufficient for the case of electron - electron ( ee ) scattering in a 2deg , where small angle scattering events dominate , and scattered electrons may remain within the region of the electron beam @xcite . for an adequate theoretical description of ee - scattering
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Suppose that you have an abstract for a scientific paper: we introduce a sub - grid model for the non - equilibrium abundance of molecular hydrogen in cosmological simulations of galaxy formation .
we improve upon previous work by accounting for the unresolved structure of molecular clouds in a phenomenological way which combines both observational and numerical results on the properties of the turbulent interstellar medium .
we apply the model to a cosmological simulation of the formation of a milky way - sized galaxy at @xmath0 , and compare the results to those obtained using other popular prescriptions that compute the equilibrium abundance of h@xmath1 . in these runs
we introduce an explicit link between star formation and the local h@xmath1 abundance , and perform an additional simulation in which star formation is linked directly to the density of cold gas . in better agreement with observations ,
we find that the simulated galaxy produces less stars and harbours a larger gas reservoir when star formation is regulated by molecular hydrogen . in this case
, the galaxy is composed of a younger stellar population as early star formation is inhibited in small , metal poor dark - matter haloes which can not efficiently produce h@xmath1 .
the number of luminous satellites orbiting within the virial radius of the galaxy at @xmath0 is reduced by 10 - 30 per cent in models with h@xmath1-regulated star formation .
[ firstpage ] methods : numerical - ism : molecules - galaxies : evolution - galaxies : formation .
And you have already written the first three sentences of the full article: the process of galaxy formation involves the interplay of many non - linear phenomena that span a wide range of length and time - scales . a galaxy like our milky way , for example , forms from a region that initially extends to roughly one comoving mpc , yet its angular momentum is determined by the mass distribution within tens of comoving mpc . star formation ( sf ) , on the other hand , takes place in the densest cores of giant molecular clouds ( gmcs ) , on scales of the order of 0.1 pc .
the challenge in simulations of galaxy formation is to capture this vast dynamic range , while simultaneously accounting for the different physical processes that intervene on relevant scales .
this is usually achieved with ad hoc sub - grid models that attempt to emulate the most important small - scale phenomena . in particular ,.
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one of the biggest uncertainties in simulations of galaxy formation is the means by which gas is converted into stars ( see * ? ? ? * for a recent review ) .
the standard approach to this problem , motivated by observations , is to adopt a schmidt - like law @xcite , often coupled to conditions on the local gas properties .
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Suppose that you have an abstract for a scientific paper: we have studied the electronic structure of the spin - gapped system csv@xmath0o@xmath1 by means of an _ ab initio _ calculation .
our analysis and a re - examination of the susceptibility data indicate that the behavior of this system is much closer to that of an alternating spin-@xmath2 antiferromagnetic chain with significant inter - dimer coupling and weaker inter - chain couplings than that of isolated dimers as was initially proposed .
comparison to the vanadate family members @xmath3-nav@xmath0o@xmath1 , @xmath4-liv@xmath0o@xmath1 and isostructural compounds like ( vo)@xmath5p@xmath5o@xmath6 is discussed .
pacs numbers : 75.30.gw , 75.10.jm , 78.30.-j .
And you have already written the first three sentences of the full article: low - dimensional spin - gapped quantum systems are of current interest since they show interesting ground states and a variety of unconventional low - lying excitations . examples of such systems include spin-1 haldane chains @xcite , spin-@xmath2 even - leg ladders@xcite and spin-@xmath2 alternating chains @xcite .
the discovery of appropriate compounds like y@xmath0banio@xmath1@xcite ( haldane chain ) , sr@xmath7cu@xmath8o@xmath9 @xcite or srcu@xmath0o@xmath10 @xcite ( ladder systems ) has brought new insight into the study of these systems .
there is a long list of various spin-@xmath2 alternating chain systems which are being intensively studied in connection to their magnetic excitations , to mention a few of them kcucl@xmath10 @xcite , tlcucl@xmath10 @xcite , cu(no@xmath10)@xmath0.@xmath11d@xmath0o @xcite ..
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if frustration is also present new features appear in the magnetization spectrum of the low - dimensional quantum systems as in cugeo@xmath10 @xcite , ( vo)@xmath0p@xmath0o@xmath12 ( vopo ) @xcite , srcu@xmath0(bo@xmath10)@xmath0 @xcite or in the recently synthesized cu@xmath0te@xmath0o@xmath1br@xmath0 @xcite .
an important family of low - dimensional compounds are the layered vanadates av@xmath0o@xmath1 ( a = ca , mg , na , li , cs)@xcite . while cav@xmath0o@xmath1 and mgv@xmath0o@xmath1 contain only magnetic v@xmath13 ions and behave like spin-@xmath2 ladders with spin - gaps of the order of 600k @xcite and 20k @xcite respectively , @xmath3-nav@xmath0o@xmath1 , @xmath4-liv@xmath0o@xmath1 and csv@xmath0o@xmath1 are mixed - valence systems ( v@xmath14 on average ) with important charge and spin fluctuations .
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Suppose that you have an abstract for a scientific paper: in this paper , arnold diffusion is proved to be generic phenomenon in nearly integrable convex hamiltonian systems with three degrees of freedom : @xmath0 under typical perturbation @xmath1 , the system admits connecting " orbit that passes through any two prescribed small balls in the same energy level @xmath2 provided @xmath3 is bigger than the minimum of the average action , namely , @xmath4 . .
And you have already written the first three sentences of the full article: for nearly integrable hamiltonian systems , the set of kam tori has a relatively large lebesgue measure in phase space . for systems with two degrees of freedom
, it implies the dynamical stability : all orbits are stable , the variation of actions stays small for all the time as each 2-dimensional kam torus separates the 3-dimensional energy level .
however , this is a special property of lower - dimensional space , kam torus of @xmath5-dimension does not separate @xmath6-dimensional energy level if @xmath7 ..
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it is conceivable that the complement of all @xmath5-dimensional invariant tori forms dense and connected set in phase space .
this would mean that by arbitrary small changes of the initial states one would find orbits along which the action variables ultimately escape . the underlying phenomenon is now called arnold diffusion " . * conjecture * ( @xcite ) : _ the typical case in a higher - dimensional problems is topological instability : through an arbitrarily small neighborhood of any point there passes a phase trajectories along which the slow variables drift away from the initial value by a quantity of order 1 .
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Suppose that you have an abstract for a scientific paper: we reexamine the scale dependence of twist - three correlation functions relevant for the single transverse spin asymmetry in the framework of collinear factorization .
evolution equations are derived for both the flavor nonsinglet and flavor singlet distributions and arbitrary parton momenta .
our results do not agree with the recent calculations of the evolution in the limit of vanishing gluon momentum .
possible sources for this discrepancy are identified . .
And you have already written the first three sentences of the full article: large transverse single spin asymmetries ( ssas ) have been observed in different hadronic reactions and these observations generated a lot of interest .
such experiments are conceptually rather simple , but their theoretical description proved to be challenging as the leading - twist contributions to such asymmetries vanish , see @xcite for a review . over the past few years
there was a splash of theoretical activity in this field , which mainly followed two lines : the @xmath0 factorization in terms of the transverse - momentum dependent ( tmd ) distributions ( e.g. @xcite ) , or , alternatively , collinear factorization including twist - three contributions in terms of multiparton correlation functions @xcite ..
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these two techniques have their own domain of validity and were shown to be consistent with each other in the kinematic regime where they both apply @xcite .
however , practically all existing calculations have been so far at the leading order ( lo ) which corresponds , roughly speaking , to the ( generalized ) parton model . in order to test the qcd dynamics and
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Suppose that you have an abstract for a scientific paper: we obtain tight upper and lower bounds to the eigenvalues of an anharmonic oscillator with a rational potential .
we compare our bounds with results given by other approaches . .
And you have already written the first three sentences of the full article: barakat has recently proposed a shifted large
dimension expansion ( slnt ) implemented by means of the asymptotic iteration method ( aim)@xcite . according to the author , this alternative approach corrects `` serious difficulties '' of previous applications of that successful perturbation theory .
he applies this improved slnt to an anharmonic oscillator with a rational potential.
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energy function .
the results are not impressive because the perturbation series are restricted to order six and contain only four terms becuse the odd coefficients vanish .
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Suppose that you have an abstract for a scientific paper: we study electrical and thermoelectric transport properties of the surface state of the topological insulator and graphene in the presence of randomly distributed impurities . for finite impurity strength ,
the dependence of the transport coefficients as a function of gate voltage , magnetic field and impurity potential , are obtained numerically . in the limit of zero impurities ( clean limit ) ,
analytic results for the peak values of the magneto - oscillations in thermopower are derived .
analogous with the conventional two dimensional electron gas , the peak values are universal in the clean limit .
unlike graphene , in topological insulators the coupling of the electron spin to its momentum leads to a dependence of the transport coefficients on the gyromagnetic ratio ( @xmath0 ) .
we compare our results with data on graphene and identify unique signatures expected in topological insulators due to the magnetoelectric coupling . .
And you have already written the first three sentences of the full article: helical dirac fermions , massless relativistic charged particles with spin locked to their linear momentum , are proposed to exist on the surface of three dimensional topological insulators ( tis)@xcite and later confirmed in experiments@xcite on samples like bi@xmath1se@xmath2 and bi@xmath3sb@xmath4 . for compounds such as hgte and bi@xmath1se@xmath2 , surfaces with a single dirac cone have been found@xcite .
while the low energy spectrum is very similar to that of graphene , the difference in the microscopic origin of the phenomena points to subtle differences .
for example , the presence of a single dirac cone in tis , as opposed to two doubly degenerate ones in graphene , leads to significant reduction in phase space at low energies ..
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furthermore , the coupling of physical spin , rather than pseudospin ( related to sublattice symmetry ) , in tis suggests that the response in magnetic fields will be markedly different .
the key property of the surface states of tis is the magnetoelectric effect .
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Suppose that you have an abstract for a scientific paper: if the beginning of inflation is defined at the moment when the vacuum energy of the inflaton starts to dominate , the energy density of the other fields at that moment is ( by definition ) comparable to the inflaton .
although the fraction will be small at the horizon exit due to the inflationary expansion , they can alter the scale dependence of the spectrum . at the same time , velocity of the inflaton field
may not coincide with the slow - roll ( attractor ) velocity
. those dynamics could be ubiquitous but can easily alter the scale dependence of the spectrum . since the scale dependence is currently used to constrain or even exclude inflation models , it is very important to measure its shift , which is due to the dynamics that does not appear in the original inflation model .
considering typical examples , we show that the spectral index of the tensor mode is a useful measure of such effect .
precise measurement of the higher runnings of the scalar mode will be helpful in discriminating the source . .
And you have already written the first three sentences of the full article: scale - dependence of the spectrum of the curvature perturbation has been used to discriminate inflationary scenarios @xcite . in addition to the scalar mode , recent discovery of the b - mode polarization@xcite
has ignited studies of the tensor modes .
although the detection of the inflationary tensor mode by the bicep2 was not successful , it stimulated study of the mechanism of generating peculiar scale - dependence @xcite . besides those recent trends in inflationary cosmology.
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, models of particle physics ( e.g , supersymmetric models and string theory ) are expecting a large amount of scalar fields that may be dynamical in the very early stage of inflation . in the light of multi - field inflation
, those extra degrees of freedom may alter the scale - dependence of both the tensor and the scalar perturbations .
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Suppose that you have an abstract for a scientific paper: we reanalyze the constraints on light gluinos ( @xmath0 gev@xmath1 ) from the hadronic @xmath2 decays into four jets .
we find that the published opal data from the 1991 and 1992 runs exclude a light quasi - stable gluino with mass @xmath3 gev@xmath1 at more than 90% confidence level .
this limit depends little on assumptions about the gluino fragmentation and the definition of the gluino mass .
the exclusion confidence level is shown as a function of the mass .
a future projection is briefly discussed .
we also discuss quantitatively how the distributions in the bengtsson zerwas and the modified nachtmann
reiter angles change due to the finite bottom quark or gluino mass .
the analysis is limited to the leading - order calculations .
we , however , give an empirical reason to why the next - to - leading - order corrections are unlikely to change our conclusions . #
1#2 c#10=0=1ex 30 # 1 lbl-39030 + ucb - pth-96/28 + .25 in * excluding light gluinos from @xmath2 decays * 0.3 in andr de gouva and hitoshi murayama + + _ department of physics , university of california + berkeley , california 94720 _ + and + _ theoretical physics group + ernest orlando lawrence berkeley national laboratory + university of california , berkeley , california 94720 _ .3 in supersymmetry is one of the primary targets of extensive searches at various collider experiments , most importantly at cern @xmath4 collider lep and fermilab @xmath5 collider tevatron @xcite .
negative searches at these and previous colliders have already put significant constraints on the parameter space of low - energy supersymmetry . however , a light gluino below the few gev mass range has surprisingly weak experimental constraints as emphasized recently by various authors @xcite ( see , however , an opposing view @xcite ) .
it is an extremely important task to verify or exclude a gluino in this light window experimentally . while the tevatron run ii is expected to extend the reach of heavy gluinos up....
And you have already written the first three sentences of the full article: hm thanks mike barnett , john ellis , lance dixon , ian hinchliffe , and kam - biu luk for useful conversations .
we thank axel kwiatkowski for comments on the manuscript .
adg was supported by cnpq ( brazil ) , and hm was supported in part by the director , office of energy research , office of high energy and nuclear physics , division of high energy physics of the u.s ..
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department of energy under contract de - ac03 - 76sf00098 and in part by the national science foundation under grant phy-95 - 14797 .
99 for a recent review , see h. baer _
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Suppose that you have an abstract for a scientific paper: a few changes to the routines that calculate cteq parton distribution functions allow modern compilers to optimize the evaluations , while having no quantitative effect on the results .
overall computation time is reduced by a factor of 45 in matrix - element calculations , and by 1.32.5 in showering monte carlo event generators .
similar improvements in performance may be expected in any calculations relying heavily on interpolation or multiple calls to functions . .
And you have already written the first three sentences of the full article: a significant amount of time and computing resources are spent on calculating events at hadron colliders .
whether a theoretical calculation of matrix elements , or an experimental simulation of events with detector effects , one common element is the evaluation of parton distribution functions ( pdfs ) .
these functions return the probability of finding a parton ( quark or gluon ) inside of a proton , based on two parameters : the fraction of momentum carried by the parton @xmath0 , and the square of the energy scale of the process @xmath1 . because the input parameters can span several orders of magnitude , the values of these functions are stored in two - dimensional tables for a finite number of input points . an approximate result for an arbitrary input of @xmath0 and @xmath1.
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is derived by interpolating between the values obtained from the nearest table entries . in profiling ` ztop ` @xcite , a `
fortran`code written to simulate next - to - leading - order jet distributions in single - top - quark production , it has become apparent that much of the execution time of real production code is spent acquiring pdfs . upon close examination of the cteq4 and cteq5 pdf codes @xcite , a handful of trivial optimizations arise that can cut this time in half .
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Suppose that you have an abstract for a scientific paper: we analyze the structural and dynamical properties of disk - like objects formed in fully consistent cosmological simulations which include inefficient star formation .
comparison with data of similar observable properties of spiral galaxies gives satisfactory agreement , in contrast with previous findings using other codes .
this suggests that the stellar formation implementation used has allowed the formation of disks as well as guaranteed their stability . .
And you have already written the first three sentences of the full article: we present results of a detailed comparison between the parameters characterizing the structural and dynamical properties of a sample of 29 simulated disk - like objects ( dlos ) and those measured in observed spiral galaxies .
the properties we focus on are the bulge and disk structural parameters and the rotation curves , as they can be constrained with available data for observed spiral galaxies .
these data are taken principally from the compilation of galaxy structural parameters of broeils ( 1992 ) , de jong ( 1996 ) and courteau ( 1996 , 1997 ) ..
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the dlos have been identified in ap3m - sph fully consistent hierarchical hydrodynamical simulations , realizations of a cdm flat model , with @xmath0 , @xmath1 and @xmath2 , made using 64@xmath3 particles in a periodic box of comoving side 10 mpc ( h@xmath4 km s@xmath5 mpc@xmath5 ) , and where an _ inefficient _ schmidt law - like algorithm to model the stellar formation processes has been implemented ( see tissera , lambas , & abadi 1997 ; silk 1999 ) .
a surface density bulge - disk decomposition was performed on the dlos , using a double - exponential profile , @xmath6 + \sigma_{\rm d}(0)\exp[-r / r_{\rm d}].\ ] ] the resulting bulge and disk scale lengths , @xmath7 and @xmath8 , and their ratio @xmath9 , are consistent with available data ( courteau , de jong , & broeils 1996 ; de jong 1996 ; moriondo , giovanelli , & haynes 1999 ) .
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Suppose that you have an abstract for a scientific paper: we recently completed a calculation of the process @xmath0 , where @xmath1 is a heavy quark , at order @xmath2 .
as a first application of this calculation we compute the momentum correlations of @xmath3 pairs at next - to - leading - order .
this quantity is interesting since it may affect the determination of @xmath4 as measured in @xmath5 decays .
we find that the next - to - leading corrections are of moderate size , thus confirming the conclusions that can be drawn from the leading - order calculation .
.5 cm * paolo nason , * + 0.1 cm cern , th division , geneva , switzerland + .5 cm * carlo oleari * + .1 cm dipartimento di fisica , universit di milano and infn , milan , italy cern - th/97 - 92 + may 1997 .
And you have already written the first three sentences of the full article: radiative corrections to jet production in @xmath6 annihilation have been known for a long time @xcite .
previous calculations were , however , performed for massless quarks . in most practical applications
this is sufficient , since at relatively low energy , the @xmath7 fraction is strongly suppressed , and at high energy ( i.e. on the @xmath5 peek and beyond ) mass effects are presumably suppressed ..
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nevertheless there are several reasons why a next - to - leading - order calculation is desirable .
first of all , at sufficiently high energies , top pairs will be produced , and mass effects there are very likely to be important .
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Suppose that you have an abstract for a scientific paper: we propose a new dynamics of the electroweak symmetry breaking in a classically scale invariant version of the standard model .
the scale invariance is broken by the condensations of additional fermions under a strong coupling dynamics .
the electroweak symmetry breaking is triggered by negative mass squared of the elementary higgs doublet , which is dynamically generated through the bosonic seesaw mechanism .
we introduce a real pseudo - scalar singlet field interacting with additional fermions and higgs doublet in order to avoid massless nambu - goldstone bosons from the chiral symmetry breaking in a strong coupling sector .
we investigate the mass spectra and decay rates of these pseudo - nambu - goldstone bosons , and show they can decay fast enough without cosmological problems .
we further evaluate the energy dependences of the couplings between elementary fields perturbatively , and find that our model is the first one which realizes the flatland scenario with the dimensional transmutation by the strong coupling dynamics .
similarly to the conventional flatland model with coleman - weinberg mechanism , the electroweak vacuum in our model is meta - stable
. 0.6 cm su - het-13 - 2015 * a new dynamics of electroweak symmetry breaking with classically scale invariance * 1.2 cm naoyuki haba@xmath0 , hiroyuki ishida@xmath0 , noriaki kitazawa@xmath1 , and + yuya yamaguchi@xmath2 0.4 cm @xmath0graduate school of science and engineering , shimane university , + matsue 690 - 8504 , japan + @xmath1department of physics , tokyo metropolitan university , + hachioji , tokyo 192 - 0397 , japan + @xmath3department of physics , faculty of science , hokkaido university , + sapporo 060 - 0810 , japan 0.2 cm .5 in .
And you have already written the first three sentences of the full article: the origin of the electroweak symmetry breaking ( ewsb ) remains a mystery . in the standard model ( sm ) , the ewsb requires a negative mass squared for the higgs doublet scalar field , whose magnitude is set by hand .
we expect a fundamental theory which naturally gives the negative mass squared with the suitable value . in a model of supersymmetric extension of the sm
, the ewsb can be realized by so - called radiative breaking @xcite ..
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however , the supersymmetry breaking scale must be high because of no signal of super - particle at any experiments so far . in technicolor ( tc )
model @xcite , the higgs doublet field is no longer an elementary scalar field , and the ewsb is triggered by the techni - fermion condensation under strongly coupled tc gauge interaction .
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Suppose that you have an abstract for a scientific paper: the dynamics after a quantum quench is determined by the weights of the initial state in the eigenspectrum of the final hamiltonian , i.e. , by the distribution of overlaps in the energy spectrum .
we present an analysis of such overlap distributions for quenches of the anisotropy parameter in the one - dimensional anisotropic spin-1/2 heisenberg model ( xxz chain ) .
we provide an overview of the form of the overlap distribution for quenches from various initial anisotropies to various final ones , using numerical exact diagonalization .
we show that if the system is prepared in the antiferromagnetic nel state ( infinite anisotropy ) and released into a non - interacting setup ( zero anisotropy , xx point ) only a small fraction of the final eigenstates gives contributions to the post - quench dynamics , and that these eigenstates have identical overlap magnitudes .
we derive expressions for the overlaps , and present the selection rules that determine the final eigenstates having nonzero overlap .
we use these results to derive concise expressions for time - dependent quantities ( loschmidt echo , longitudinal and transverse correlators ) after the quench .
we use perturbative analyses to understand the overlap distribution for quenches from infinite to small nonzero anisotropies , and for quenches from large to zero anisotropy . .
And you have already written the first three sentences of the full article: the past decade has witnessed a tremendous resurgence of interest in the physics of quantum many - body systems out of equilibrium .
this growth has been partly motivated by remarkable developments in experiments , especially in experiments on cold atoms , which made the explicit observation of time evolution of many - body quantum systems possible @xcite .
in addition to the experimental motivation , fundamental conceptual issues , such as thermalization in isolated systems and the nature of adiabaticity , have also played a strong role in driving the development of this field ..
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a central paradigm in the study of non - equilibrium physics is the _ quantum quench_. a quantum quench involves a protocol starting from the ground state ( or a thermal state or another eigenstate ) of an ` initial ' hamiltonian @xmath0 , and then rapidly changing the hamiltonian so that nontrivial time evolution occurs under a different ( ` final ' ) hamiltonian @xmath1 .
many aspects of the dynamics induced by quantum quenches have been considered in recent years ; the literature is rapidly growing and already too vast to review here .
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Suppose that you have an abstract for a scientific paper: we investigate spontaneous photon emission processes of two - level atoms in parabolic and ellipsoidal cavities thereby taking into account the full multimode scenario .
in particular , we calculate the excitation probabilities of the atoms and the energy density of the resulting few - photon electromagnetic radiation field by using semiclassical methods for the description of the multimode scenario .
based on this approach photon path representations are developed for relevant transition probability amplitudes which are valid in the optical frequency regime where the dipole and the rotating - wave approximations apply .
comparisons with numerical results demonstrate the quality of these semiclassical results even in cases in which the wave length of a spontaneously emitted photon becomes comparable or even larger than characteristic length scales of the cavity .
this is the dynamical regime in which diffraction effects become important so that geometric optical considerations are typically not applicable . .
And you have already written the first three sentences of the full article: the investigation of resonant light - matter interaction has received considerable attention during the last decades and remarkable experimental progresses in this field has opened the door to whole new experimental opportunities @xcite .
these developments are not only interesting from a fundamental point of view but also from practical points of view for possible applications in the area of quantum information processing , for example . in this
latter context methods for achieving an optimal transfer of quantum information between single photons ( flying qubits ) and elementary material systems ( stationary qubits ) over large distances by using the resonant strong coupling , as required for the realization of a quantum repeater , are of particular interest ..
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therefore , recently considerable efforts @xcite have been devoted to investigate the interaction of matter qubits with few modes of the radiation field within the framework of jaynes - cummings - paul models @xcite .
recent developments stimulated extensions of this work to extreme multimode scenarios or to scenarios involving structured continua of electromagnetic field modes which are characteristic for half open cavities of a parabolic shape @xcite , for example . in the following we review some of these recent research activities focusing on the resonant matter - field interaction of two - level atoms located around the focal point of a parabolic shaped cavity and
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Suppose that you have an abstract for a scientific paper: we study the brownian dynamics of flexible and semiflexible polymer chains densely grafted on a flat substrate , upon rapid quenching of the system when the quality of solvent becomes poor and chains attempt collapse into a globular state .
the collapse process of such a polymer brush differs from individual chains , both in its kinetics and its structural morphology .
we find that the resulting collapsed brush does not form a homogeneous dense layer , in spite of all chain monomers equally attracting each other via a model lennard - jones potential . instead , a very distinct inhomogeneous density distribution in the plane forms , with a characteristic length scale dependent on the quenching depth ( or equivalently , the strength of monomer attraction ) and the geometric parameters of the brush .
this structure is identical to the spinodal - decomposition structure , however , due to the grafting constraint we find no subsequent coarsening : the established random bundling with characteristic periodicity remains as the apparently equilibrium structure .
we compare this finding with a recent field - theoretical model of bundling in a semiflexible polymer brush . .
And you have already written the first three sentences of the full article: the theoretical problem of polymer chain collapse in poor solvents has received much attention over the past decades , both from analytic @xcite and numerical approaches @xcite .
this generic collapse , often called the `` coil - globule transition '' , is well - understood as a local version of the polymer demixing flory has originally formulated for polymer solutions @xcite .
the coil - globule transition is closely associated with the initial stages of protein folding @xcite ..
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collapse takes place as a result of effective pair interaction between chain monomers becoming attractive , e.g. due to changing solvent quality .
recent studies of the collapse dynamics have shown that it is a non - trivial kinetic process , with competing interactions leading to inhomogeneous intermediate structures forming and persisting on the way to the final globular state @xcite . in this work ,
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Suppose that you have an abstract for a scientific paper: we present optical observations of the peculiar type ibn supernova ( sn ibn ) ogle-2012-sn-006 , discovered and monitored by the @xmath0 survey , and spectroscopically followed by @xmath1 at late phases .
stringent pre - discovery limits constrain the explosion epoch with fair precision to @xmath2 = 2456203.8 @xmath3 4.0 .
the rise time to the @xmath4-band light curve maximum is about two weeks .
the object reaches the peak absolute magnitude @xmath5 on @xmath6 .
after maximum , the light curve declines for about 25 days with a rate of 4 mag 100d@xmath7 .
the symmetric @xmath4-band peak resembles that of canonical type ib / c supernovae ( sne ) , whereas sne ibn usually exhibit asymmetric and narrower early - time light curves . since
25 days past maximum , the light curve flattens with a decline rate slower than that of the @xmath8co to @xmath8fe decay , although at very late phases it steepens to approach that rate .
however , other observables suggest that the match with the @xmath8co decay rate is a mere coincidence , and the radioactive decay is not the main mechanism powering the light curve of ogle-2012-sn-006 . an early - time spectrum is dominated by a blue continuum , with only a marginal evidence for the presence of he i lines marking this sn type .
this spectrum shows broad absorptions bluewards than 5000 , likely o ii lines , which are similar to spectral features observed in super - luminous sne at early epochs .
the object has been spectroscopically monitored by @xmath1 from 90 to 180 days after peak , and these spectra show the typical features observed in a number of sn 2006jc - like events , including a blue spectral energy distribution and prominent and narrow ( @xmath9
km s@xmath7 ) he i emission lines .
this suggests that the ejecta are interacting with he - rich circumstellar material .
the detection of broad ( @xmath10 km s@xmath7 ) o i and ca ii features likely produced in the sn ejecta ( including the [ o i ] @xmath116300,6364 doublet in the latest spectra )....
And you have already written the first three sentences of the full article: supernovae of type ibn ( sne ibn ) are considered a rare group of stripped - envelope core - collapse ( cc ) events which interact with h - depleted circumstellar material ( csm ) .
the spectra of sne ibn are characterized by relatively narrow lines of he i in emission ( hence the designation as ibn , * ? ? ?
* ) , with full - width at half maximum ( fwhm ) velocities ranging from several hundreds to a few thousands km s@xmath7 ..
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these features are thought to arise in the interactions between the sn ejecta and he - rich ( and h - poor ) csm .
however , weak h lines have been occasionally detected in the spectra of a few type ibn sne , suggesting the presence of residual h in the csm of -at least- a sub - sample of sne ibn @xcite .
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Suppose that you have an abstract for a scientific paper: we construct branched double coverings by certain direct products of manifolds for connected sums of copies of sphere bundles over the 2-sphere . as an application we answer a question of kotschick and
lh up to dimension five .
more precisely , we deduce that every simply connected , closed four - manifold admits a branched double covering by a product of the circle with a connected sum of copies of @xmath0 , followed by a collapsing map .
furthermore , every simply connected , closed five - manifold admits a branched double covering by a product of the circle with a connected sum of copies of @xmath1 , followed by a map whose degree is determined by the torsion of the second integral homology group of the target . .
And you have already written the first three sentences of the full article: the realization of manifolds as branched coverings is a classical long - standing problem in topology . a well - known theorem of alexander @xcite states that every oriented , closed , smooth @xmath2-dimensional manifold is a branched covering of @xmath3 .
strong restrictions for the existence of branched coverings were found by berstein and edmonds @xcite . branched coverings
have been investigated in many different contexts and they turned out to be a useful tool for the study of several problems in geometry , such as the minimal genus problem in four dimensions ..
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recall that a branched @xmath4-fold covering is a smooth proper map @xmath5 with a codimension two subcomplex @xmath6 , called the branch locus of @xmath7 , such that @xmath8 is a @xmath4-fold covering in the usual sense and for each @xmath9 the map @xmath7 is given by @xmath10 , for some charts of @xmath11 and @xmath12 and some positive integer @xmath13 .
the point @xmath11 is called singular and its image @xmath12 is called a branch point . in dimensions two and three
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Suppose that you have an abstract for a scientific paper: the cross sections of @xmath0 to @xmath1wave and @xmath2wave quarkonia with @xmath3-parity even associated with a photon are analyzed in the framework of non - relativistic quantum chromodynamics(nrqcd ) factorization formulism .
the short - distance coefficients are analytically determined up to the next - to - leading order(nlo ) qcd radiative corrections to @xmath1wave and @xmath2wave quarkonium production and nlo relativistic correction to @xmath4 production .
we also invoke the analytical expressions to estimate the cross sections .
our numerical results indicate that both the qcd and the relativistic corrections are considerable . .
And you have already written the first three sentences of the full article: non - relativistic quantum chromodynamics(nrqcd ) factorization formalism@xcite is an useful tool for analyzing the inclusive production of the heavy quarkonium . according to it
, the cross section is expressed as a sum of products of short - distance coefficients and nrqcd matix elements .
the short - distance coefficients can be calculated as perturbation series in coupling constant @xmath5 at the scale of the heavy quark mass ..
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the matrix elements scale in a definite way with the typical relative velocity @xmath6 of heavy quark in the quarkonium state .
thus the production cross sections can be expressed as double expansions both in @xmath5 and in @xmath6 to any desired order .
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Suppose that you have an abstract for a scientific paper: we report calculations of the electronic structure of silicene and the stability of its weakly buckled honeycomb lattice in an external electric field oriented perpendicular to the monolayer of si atoms .
the electric field produces a tunable band gap in the dirac - type electronic spectrum , the gap being suppressed by a factor of about eight by the high polarizability of the system . at low electric fields , the interplay between this tunable band gap , which is specific to electrons on a honeycomb lattice , and the kane - mele spin - orbit coupling induces a transition from a topological to a band insulator , whereas at much higher electric fields silicene becomes a semimetal . .
And you have already written the first three sentences of the full article: two - dimensional ( 2d ) carbon crystals are hosts for dirac - type electrons , whose unusual properties have been studied extensively in graphene monolayers produced by mechanical exfoliation from graphite.@xcite a close relative of graphene , a 2d honeycomb lattice of si atoms called
_ silicene_,@xcite does not occur in nature , but nanoribbons of silicene have been synthesized on metal surfaces.@xcite due to the similarity of the lattice structures , the band structure of silicene resembles that of graphene , featuring dirac - type electron dispersion in the vicinity of the corners of its hexagonal brillouin zone ( bz).@xcite moreover , silicene has been shown theoretically to be metastable as a free - standing 2d crystal,@xcite implying that it is possible to transfer silicene onto an insulating substrate and gate it electrically . in this work
we predict the properties of this 2d crystal ..
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the similarity between graphene and silicene arises from the fact that c and si belong to the same group in the periodic table of elements .
however , si has a larger ionic radius , which promotes sp@xmath0 hybridization , whereas sp@xmath1 hybridization is energetically more favorable in c. as a result , in a 2d layer of si atoms , the bonding is formed by mixed sp@xmath1 and sp@xmath0 hybridization .
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Suppose that you have an abstract for a scientific paper: we report the existence of self propelled janus droplets driven by phase separation , which are able to deliver cargo in a programmable manner .
the self propelling droplets are initially formed by a water / ethanol mixture in a squalane / monoolein solution , and evolve in up to three stages depending on ethanol concentration . in the first stage ,
the droplet propulsion is generated by marangoni flow originating from the solubilization of ethanol in the oily phase . during this process
the droplets absorb surfactant molecules ; in combination with the continuous loss of ethanol this leads to a phase separation of the water / ethanol / monoolein mixture and the formation of janus droplets , i.e. a water
rich droplet connected to an ethanol rich droplet that is able to deliver cargo .
we characterize the different evolution stages of self - propulsion by the flow field around the droplet that evolves from a weak pusher , over a neutral swimmer , to a dimer of neutral swimmers .
finally , we utilize this active system to deliver dna as a cargo . tuning the delay time before phase separation , by varying the chemical composition of the droplets ,
several different cargo delivery processes can be programmed . .
And you have already written the first three sentences of the full article: in recent years , significant efforts were dedicated to realize artificial micro and nano swimmers that locomote at low reynolds numbers , and that are further able to perform tasks , like cargo delivery @xcite .
swimmers driven by periodic conformational changes have to break the time - reversal symmetry to achieve a net propulsion at small reynolds numbers @xcite .
however , swimmers driven by a continuous propulsion mechanism need to break spatial symmetry and display a permanent polarity . despite the theoretical possibility to observe a spontaneous symmetry breaking for homogeneous spherical particles @xcite , all solid autophoretic swimmers realized in experiments so far exhibit an ingrained polarity ..
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spherical janus particles , for instance , exploit a difference in chemical surface composition of the two opposing hemispheres @xcite .
recent studies have shown that janus nanorods can not only self propel but also deliver drugs during self
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Suppose that you have an abstract for a scientific paper: the deconfinement transition in 3 + 1 dimensional gluodynamics is studied using the gauge invariant variational method introduced by kogan and kovner a few years ago .
we identify a first order phase transition , characterized by a discontinuous jump in the entropy of the system , resulting in a transparent picture of the mechanism of deconfinement .
the calculation of the ratio of the transition temperature to the mass of the lightest glueball in the model yields 0.18 in complete agreement with the lattice estimate . .
And you have already written the first three sentences of the full article: in the almost 25 years since the pioneering work of polyakov @xcite and susskind @xcite much effort has been devoted to attempts to understand both the basic physics and quantitave features of the deconfining phase transition of qcd . the high temperature phase , i.e. for temperatures well above the critical temperature @xmath0 , is becoming well understood , and is widely believed to resemble a plasma of almost free quarks and gluons .
however , the transition region , @xmath1 , is very poorly understood .
this region is the most interesting one since it is there that the transition between ` hadronic ' and ` partonic ' degrees of freedom occurs ..
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the study of the transition region is a complicated and inherently non - perturbative problem which has mostly evaded treatment by analytical methods .
the variational method introduced several years by kogan and kovner @xcite appears well suited to a discussion of such a problem .
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Suppose that you have an abstract for a scientific paper: we use the sstl ( singwi , sjlander , tosi , land ) approximation to investigate the short range correlations in a one dimensional electron gas , for the first time .
although sstl is introduced to better satisfy the compressibility sum rule in three dimensions , the widely used stls ( singwi , tosi , land , sjlander ) approximation turns out to be more successful in the case of the one dimensional electron gas .
16.3 true cm 23.0 true cm -0.8 true in 0.00 true in keywords : quantum wires ; screening ; compressibility .
And you have already written the first three sentences of the full article: the advances in fabrication technologies have made it possible to experimentally fabricate one dimensional electronic structures@xcite@xcite .
this has naturally resulted in an increasing interest in theoretical investigations of such structures@xcite@xcite .
the resulting one dimensional electron gas has also been subject to computational investigation@xcite ..
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the extensive investigations in the three dimensional electron gas have clearly shown the importance of the short range correlations at lower densities in determining the pair distribution function @xmath0 at small @xmath1@xcite . in the high density limit , the long range correlations can be described well by the random phase approximation ( rpa ) .
one way to include the short range correlation effects beyond rpa is to use the powerful approach developed by stls@xcite .
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Suppose that you have an abstract for a scientific paper: in this paper i will review the dynamical models that attempt to explain the outflows in qsos and seyfert galaxies that are responsible for the blue shifted absorption lines observed in some of these objects .
most models face the difficulty that the absorbing gas appears to consist of very small , low filling factor clouds , that are likely to be hydrodynamically unstable , and require an intercloud medium at high pressure to keep them confined .
two types of intercloud medium have been proposed : hot gas and magnetic field .
hot gas confinement leads to many apparent physical contradictions , and until these are resolved can not be considered a serious candidate .
magnetic confinement seems more promising , but needs more study to assess its viability .
a third possibility that should be seriously considered in the light of the confinement problem is that some of the arguments leading to the conclusion that a small filling factor is required is wrong . as an example , murray et al . showed that a model that allows the ionization parameter of the absorbing gas to be much higher than generally thought can avoid the confinement problem .
three types of acceleration mechanisms have been considered for wind - like outflows in agn : hot gas or cosmic ray pressure driven winds , winds driven by radiation pressure and centrifugally driven magnetic disk winds .
the first two have been shown to be able to produce absorption lines similar to the observed ones , with line radiation pressure requiring the smallest leaps of faith .
the formation of absorption lines in magnetic winds is still unexplored . .
And you have already written the first three sentences of the full article: the existence of broad absorption line quasars and blue shifted absorption lines in seyferts provides clear evidence that high speed outflows of gas are common in agn .
the basic questions one would like to have answered by a theoretical model for these outflows are : * what is the origin of the gas flowing out ? * what is its geometry ? *
what force accelerates it ? * what determines its ionization state ?.
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while answering these questions , a good model should satisfy these observational constraints : * it should produce lines similar to the observed ones .
significant column densities ( @xmath0 to @xmath1 @xmath2 ) of both high ionization potential ions ( o vi , n v , civ etc . ) and low ionization potential ions ( o iii , si iv ) should be produced .
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Suppose that you have an abstract for a scientific paper: the discriminants of certain polynomials related to chebyshev polynomials factor into the product of two polynomials , one of which has coefficients that are much larger than the other s .
remarkably , these polynomials of dissimilar size have `` almost '' the same roots , and their discriminants involve exactly the same prime factors . .
And you have already written the first three sentences of the full article: the discriminants of the chebyshev @xmath0 and @xmath1 polynomials are given by simple and elegant formulas : @xmath2 and @xmath3 is there anything comparable for linear combinations or integral transforms of chebyshev polynomials ? for a special type of linear combination , formula was generalized in @xcite to @xmath4 where @xmath5 for various formulas related to this type of linear combination , see @xcite and @xcite .
what can be said about discriminants in @xmath6 of an integral transform @xmath7 where @xmath8 is some chebyshev polynomial ?
our goal here is to show that the resulting polynomials have discriminants that factor in a remarkable way ..
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more precisely , when @xmath9 the discriminant factors into two polynomials , one of which has coefficients that are much larger than the coefficients of the other .
moreover , these two polynomials have `` almost '' the same roots , and their discriminants involve exactly the same prime factors .
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Suppose that you have an abstract for a scientific paper: * abstract : * current experiments do not exclude the possibility that one or more neutrinos are very slightly superluminal or that they have a very small tachyonic mass .
important bounds on the size of a hypothetical tachyonic neutrino mass term are set by lepton pair erenkov radiation ( lpcr ) , i.e. , by the decay channel @xmath0 which proceeds via a virtual @xmath1 boson . here
, we use a lorentz - invariant dispersion relation which leads to very tight constraints on the tachyonic mass of neutrinos ; we also calculate decay and energy loss rates . a possible cutoff seen in the icecube neutrino spectrum for @xmath2 , due to the potential onset of lpcr
, is discussed . .
And you have already written the first three sentences of the full article: the early arrival of a neutrino burst from the 1987a supernova @xcite still motivates speculations about a possible superluminal nature of neutrinos , even if it is generally assumed that the delay in the arrival of electromagnetic radiation ( light ) is caused by the time the shock wave from the core collapse needs in order to reach the surface of the exploding star .
if neutrinos are ever so slightly superluminal , then they may emit erenkov radiation in the form of light lepton pairs . in this paper
, we attempt to answer three questions : _ ( i ) ..
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_ how would the energy threshold for the decay channel @xmath0 ( lepton pair erenkov radiation , lpcr ) have to be calculated if we assume a strictly lorentz - covariant , space - like dispersion relation for the relevant neutrino flavor eigenstate ? _ ( ii ) .
_ how would the decay rate and the energy loss rate have to be calculated under this assumption ?
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Suppose that you have an abstract for a scientific paper: this paper discusses the enumeration of two - terminal series - parallel networks , i.e. the number of electrical networks built with @xmath0 identical elements connected in series or parallel with two - terminal nodes .
they frequently occur in applied probability theory as a model for real networks .
the number of networks grows asymptotically like @xmath1 , as for some models of statistical physics like self - avoiding walks , lattice animals , meanders , etc . by using a exact recurrence relation ,
the entropy is numerically estimated at @xmath2 , and we show that the sub - leading `` universal '' exponent @xmath3 is 3/2 . #
1#2 ( c # 1 + # 2 ) .
And you have already written the first three sentences of the full article: the series - parallel networks are one of the simplest models of real networks .
then even if it is at last one century old ( mac mahon 1892 ) , it still occurs frequently in both theoretical or applied studies .
some questions like the reliability ( feo and johnson 1990 ) , the survival probability after failures , the routing problem and the queuing delay ( tamir 1993 ) , etc ..
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are now an important branch of probability theory applied to communication , computer or power networks . as usual in this kind of model , the elementary components ( resistances or switches )
are chosen all identical .
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Suppose that you have an abstract for a scientific paper: this paper proposes a simple procedure to decide whether the empirically - observed adjacency or weights matrix , which characterizes the graph underlying a socio - economic network , is sufficiently symmetric ( respectively , asymmetric ) to justify an undirected ( respectively , directed ) network analysis .
we introduce a new index that satisfies two main properties .
first , it can be applied to both binary or weighted graphs .
second , once suitably standardized , it distributes as a standard normal over all possible adjacency / weights matrices . to test the index in practice , we present an application that employs a set of well - known empirically - observed social and economic networks . .
And you have already written the first three sentences of the full article: in the last years , the literature on networks has been characterized by exponential growth .
empirical and theoretical contributions in very diverse fields such as physics , sociology , economics , etc . have increasingly highlighted the pervasiveness of networked structures .
examples range from www , the internet , airline connections , scientific collaborations and citations , trade and labor market contacts , friendship and other social relationships , business relations and r&s partnerships , all the way through cellular , ecological and neural networks @xcite ..
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the empirical research has thoroughly studied the ( often complex ) topological properties of such networks , whereas a large number of theoretical models has been proposed in order to investigate how networks evolve through time @xcite .
structural properties of networks have been shown to heavily impact on the dynamics of the socio - economic systems that they embed @xcite . as a result ,
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Suppose that you have an abstract for a scientific paper: we address recent criticisms ( liu et al . , 2015 ;
ferrer - i - cancho and gmez - rodrguez , 2015 ) of our work on empirical evidence of dependency length minimization across languages ( futrell et al . , 2015 ) .
first , we acknowledge error in failing to acknowledge liu ( 2008 ) s previous work on corpora of 20 languages with similar aims
. a correction will appear in pnas .
nevertheless , we argue that our work provides novel , strong evidence for dependency length minimization as a universal quantitative property of languages , beyond this previous work , because it provides baselines which focus on word order preferences .
second , we argue that our choices of baselines were appropriate because they control for alternative theories . in recent work
, we addressed the question of whether dependency length
the distance between syntactically related words in natural language sentences is shorter than one would expect under random baselines ( futrell et al . , 2015 )
this idea has linguistic relevance because if one hypothesizes a universal pressure to minimize dependency length , one can explain a variety of universal properties of languages , including many of the word - order universals noted by greenberg ( 1963 ) .
evidence that language users perfer word orders with shorter dependency length than chance supports this hypothesis , known as the dependency length minimization ( dlm ) hypothesis .
the dlm hypothesis is theoretically attractive because it is motivated by general human information processing constraints : minimizing dependency length minimizes the online memory load for human sentence parsing and generation .
two recent articles have raised important criticisms of our work ( liu et al . , 2015 ;
ferrer - i - cancho & gmez - rodrguez , 2015 ) . .
And you have already written the first three sentences of the full article: first , liu et al . ( 2015 ) note correctly that we failed to cite a previous large - scale empirical study with similar aims .
in particular , liu ( 2008 ) compares average dependency length in attested sentences of 20 languages to dependency length in random trees . not acknowledging this important prior work was an error on our part .
the reason for this omission is that , in all honesty , we did not fully understand this paper and its relationship to ours until conversations with liu and colleagues after publication ..
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but these are not good reasons : we acknowledge that we should have made more of an effort to understand and acknowledge prior similar work .
consequently , we apologize and we urge anyone pursuing research relating to our paper to also study liu ( 2008 ) .
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Suppose that you have an abstract for a scientific paper: given a finite group @xmath0 , a @xmath0-covering of closed riemannian manifolds , and a so - called @xmath0-relation , a construction of sunada produces a pair of manifolds @xmath1 and @xmath2 that are strongly isospectral .
such manifolds have the same dimension and the same volume , and their rational homology groups are isomorphic . here
, we investigate the relationship between their integral homology .
the cheeger
mller theorem implies that a certain product of orders of torsion homology and of regulators for @xmath1 agrees with that for @xmath2 .
we exhibit a connection between the torsion in the integral homology of @xmath1 and @xmath2 on the one hand , and the @xmath0-module structure of integral homology of the covering manifold on the other , by interpreting the quotients @xmath3 representation theoretically .
further , we prove that the @xmath4-torsion in the homology of @xmath1 is isomorphic to that of @xmath2 for all primes @xmath5 . for @xmath6 ,
we give examples of pairs of strongly isospectral hyperbolic @xmath7-manifolds for which the @xmath8-torsion homology differs , and we conjecture such examples to exist for all primes @xmath8 .
-0.8 cm .
And you have already written the first three sentences of the full article: two closed riemannian manifolds @xmath1 and @xmath2 are said to be _ isospectral _ if the laplace beltrami operators acting on functions on @xmath1 and on @xmath2 have the same spectrum , equivalently if the spectral zeta functions @xmath9 and @xmath10 are equal .
the manifolds are said to be _ strongly isospectral _ if the spectra of every natural self - adjoint elliptic differential operator on @xmath1 and @xmath2 agree .
in particular , if @xmath1 and @xmath2 are strongly isospectral , then the laplace de rham operators acting on differential @xmath11-forms on the respective manifold have the same spectrum , equivalently the zeta functions @xmath12 and @xmath13 encoding those spectra are equal . following kac s famous question `` can one hear the shape of a drum ? ''.
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@xcite , the following broad questions have received a lot of attention @xcite .
[ q:1 ] which isometry invariants of closed riemannian manifolds are isospectral invariants ? which ones are strongly isospectral invariants ?
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Suppose that you have an abstract for a scientific paper: during the first 20 seconds of its life , the enormous neutrino luminosity of a neutron star drives appreciable mass loss from its surface .
previous investigations have shown that this neutrino - driven wind could be the site where the @xmath0-process occurs .
the nucleosynthesis is sensitive to four physical parameters characterizing the wind : its mass loss rate , the entropy per baryon , the electron fraction , and the dynamic time scale .
different authors , using numerical models for supernovae , have arrived at qualitatively different values for these key parameters . here
we derive their values analytically and test our analytic results by numerical calculations using an implicit hydrodynamic code . employing our analytic and numerical methods , we also investigate how various factors can affect our results .
the derived entropy typically falls short , by a factor of two to three , of the value required to produce a strong @xmath0-process .
various factors that might give a higher entropy or a more rapid expansion in the wind are discussed . .
And you have already written the first three sentences of the full article: recent years have seen progress in our understanding of both the type ii supernova mechanism and heavy element nucleosynthesis .
an intriguing suggestion has been that the origin of the @xmath0-process is in the neutrino - driven wind of a young neutron star ( woosley & hoffman 1992 , see also meyer et al .
1992 ; howard et al . 1993 ; witti , janka , & takahashi 1994 ; and takahashi , witti , & janka 1994 ) ..
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the winds leave the neutron star about 1 to 20 s after its creation by the stellar core collapse .
the mass loss is sustained by neutrino heating during the kelvin - helmholtz cooling phase of the neutron star .
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Suppose that you have an abstract for a scientific paper: here we study and compare the sensitivity to the higgs sector of susy - seesaw models via the lfv tau decays : @xmath0 , @xmath1 , @xmath2 and @xmath3 .
we emphasize that , at present , the two latter channels are the most efficient ones to test indirectly the higgs particles .. address = departamento de fsica terica and instituto de fsica terica , ift - uam / csic + universidad autnoma de madrid , cantoblanco , e-28049 madrid , spain address = ific , universitat de valncia - csic , apt .
correus 22085 , e-46071 valncia , spain address = departamento de fsica terica and instituto de fsica terica , ift - uam / csic + universidad autnoma de madrid , cantoblanco , e-28049 madrid , spain .
And you have already written the first three sentences of the full article: lepton flavor violating ( lfv ) tau decays provide one of the most efficient indirect tests of supersymmetric ( susy ) models with extended neutrino sector , if the seesaw mechanism for neutrino mass generation is implemented . here
we assume susy - seesaw models with the mssm particle content plus three right handed neutrinos , @xmath4 @xmath5 , and their corresponding susy partners , @xmath6 , and use the parameterisation for the yukawa couplings given by @xmath7 , with @xmath8 defined by three complex angles @xmath9 ; @xmath10 , @xmath11 gev ; @xmath12 denotes the three light neutrino masses , and @xmath13 the three heavy ones . with this parameterisation
it is easy to accommodate the @xmath14 data and also get large @xmath15 , by choosing large @xmath16 and/or @xmath9 ..
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the sensitivity to the higgs sector of these susy - seesaw models can appear only via the lfv processes that are mediated by higgs particles .
this is the case of the tau decay channels considered here , whose present experimental bounds are respectively at br@xmath17 , br@xmath18 , br@xmath19 and br@xmath20 ( assuming br@xmath21 ) .
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Suppose that you have an abstract for a scientific paper: we have used the rosat all - sky survey to detect a known supercluster at @xmath0 in the north ecliptic pole region .
the x - ray data greatly improve our understanding of this supercluster s characteristics , approximately doubling our knowledge of the structure s spatial extent and tripling the cluster / group membership compared to the optical discovery data .
the supercluster is a rich structure consisting of at least 21 galaxy clusters and groups , 12 agn , 61 iras galaxies , and various other objects .
a majority of these components were discovered with the x - ray data , but the supercluster is also robustly detected in optical , ir , and uv wavebands . extending @xmath1mpc)@xmath2 , the north ecliptic pole supercluster has a flattened shape oriented nearly edge - on to our line - of - sight . owing to the softness of the rosat x - ray passband and the deep exposure over a large solid angle , we have detected for the first time a significant population of x - ray emitting galaxy groups in a supercluster .
these results demonstrate the effectiveness of x - ray observations with contiguous coverage for studying structure in the universe . .
And you have already written the first three sentences of the full article: superclusters ( scs ) are the ultimate manifestation of hierarchical large - scale structure ( lss ) in the universe . with a median major axis of @xmath3mpc ( jaaniste et al .
1998 ) , they are the most massive and the largest possibly bound structures known
. `` great walls '' of galaxies have been discovered that are larger than what one normally calls a sc , but they are almost certainly not gravitationally bound ( geller & huchra 1989 ) ..
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observations and numerical simulations suggest that a rich hierarchy of constituents trace a sc .
massive galaxy clusters are linked by smaller galaxy groups in the high - density regions , while filamentary distributions of galaxies fill out the expansive , low - density domains .
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Suppose that you have an abstract for a scientific paper: we find a larger class of virtually fibred classic montesinos links of type @xmath0 , extending a result of agol , boyer and zhang . .
And you have already written the first three sentences of the full article: a @xmath1-manifold is called _ virtually fibred _ if it has a finite cover which is a surface bundle over the circle . a link in a connected @xmath1-manifold is said to be _ virtually fibred _ if its exterior is a virtually fibred @xmath1-manifold .
thurston conjectured that all closed hyperbolic @xmath1-manifolds and all hyperbolic links in closed @xmath1-manifolds are virtually fibred .
this conjecture , which has been named as _ virtually fibred conjecture _.
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, is one of the most fundamental and difficult problems in @xmath1-manifold topology .
recall that a link @xmath2 in @xmath3 is called a _ generalized montesinos link _ if the double branched cover @xmath4 of @xmath5 is a seifert fibred @xmath1-manifold .
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Suppose that you have an abstract for a scientific paper: the recent measurement of the shapiro delay in the radio pulsar psr j1614@xmath02230yielded a mass of [email protected] @xmath2 , making it the most massive pulsar known to date .
its mass is high enough that , even without an accompanying measurement of the stellar radius , it has a strong impact on our understanding of nuclear matter , gamma - ray bursts , and the generation of gravitational waves from coalescing neutron stars .
this single high mass value indicates that a transition to quark matter in neutron - star cores can occur at densities comparable to the nuclear saturation density only if the quarks are strongly interacting and are color superconducting .
we further show that a high maximum neutron - star mass is required if short duration gamma - ray bursts are powered by coalescing neutron stars and , therefore , this mechanism becomes viable in the light of the recent measurement . finally , we argue that the low - frequency ( @xmath3 hz ) gravitational waves emitted during the final stages of neutron - star coalescence encode the properties of the equation of state because neutron stars consistent with this measurement can not be centrally condensed .
this will facilitate the measurement of the neutron star equation of state with advanced ligo / virgo . .
And you have already written the first three sentences of the full article: neutron stars are associated with the most diverse and energetic phenomena in the universe , from gamma - ray bursts to the emission of gravitational waves and from periodic millisecond radio signals to month - long x - ray outbursts .
the strength and even the occurrence of some of these phenomena depend on the neutron star mass . for decades
, precise dynamical measurements of the masses of neutron stars resulted in highly clustered values around 1.251.4 solar masses @xcite ..
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this paradigm has recently changed with the measurement of the neutron star mass for psr j1614@xmath02230 .
psr j1614@xmath02230 is a 3.1 ms radio pulsar in a 8.7 day orbit around a massive white dwarf @xcite .
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Suppose that you have an abstract for a scientific paper: we consider the time - correlated multiple - antenna interference channel where the transmitters have ( i ) _ delayed _ channel state information ( csi ) obtained from a latency - prone feedback channel as well as ( ii ) imperfect _ current _ csit , obtained e.g. from prediction on the basis of these past channel samples .
we derive the degrees of freedom ( dof ) region for the two - user multiple - antenna interference channel under such conditions . the proposed dof achieving scheme exploits a particular combination of the space - time alignment protocol designed for fully outdated csit feedback channels ( initially developed for the broadcast channel by maddah - ali et al , later extended to the interference channel by vaze et al . and ghasemi et al . )
together with the use of simple zero - forcing ( zf ) precoders .
the essential ingredient lies in the quantization and feedback of the residual interference left after the application of the initial imperfect zf precoder .
our focus is on the miso setting albeit extensions to certain mimo cases are also considered . .
And you have already written the first three sentences of the full article: although the determination of capacity region of the interference channel ( ic ) has been a long standing open problem , several interesting recent results shed light on the problem from various perspectives . among these
we may cite the capacity region obtained for special cases @xcite , or obtained for general channel classes in both scalar and mimo settings up to approximations with bounded gaps @xcite .
when specializing to the large snr regime , it is known that the characterization of the full capacity region can be conveniently replaced with the determination of the so - called degree - of - freedom ( dof ) region ..
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progress on that particular front was reported in @xcite with the derivation of the dof region for the two - user mimo interference channel with @xmath0 , @xmath1 transmit antennas and @xmath2 , @xmath3 receive antennas , where the sum dof @xmath4 is shown to be optimal .
most of these advances suggest achievable schemes which require the full knowledge of channel state information ( csi ) at both the transmitter and receiver sides .
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10,553 |
Suppose that you have an abstract for a scientific paper: a tethered surface model is investigated by using the canonical monte carlo simulation technique on a torus with an intrinsic curvature .
we find that the model undergoes a first - order phase transition between the smooth phase and the crumpled one . and phase transition , intrinsic curvature , elastic membranes 64.60.-i , 68.60.-p , 87.16.dg .
And you have already written the first three sentences of the full article: recently , it has been growing that the concern with elastic surface models of helfrich and polyakov - kleinert @xcite .
a considerable number of studies have been conducted on the phase transition between the smooth phase and the crumpled one over the past two decades @xcite .
curvature energies play a crucial role in smoothing the surface . according to curvature energies.
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, surface models can be divided into two classes ; one with an extrinsic curvature and the other with an intrinsic curvature .
it is also possible that both extrinsic and intrinsic curvatures are included in a model hamiltonian .
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10,554 |
Suppose that you have an abstract for a scientific paper: we present an investigation of possible fueling mechanisms operating in the inner kiloparsec of seyfert galaxies .
we analyze visible and near - infrared _ hubble space telescope _ images of 24 seyfert 2s from the cfa redshift survey sample .
in particular , we are searching for the morphological signatures of dynamical processes reponsible for transporting gas from kiloparsec scales into the nucleus .
the circumnuclear regions are very rich in gas and dust , often taking the form of nuclear spiral dust lanes on scales of a few hundred parsecs .
while these nuclear spirals are found in 20 of our 24 seyferts , we find only 5 nuclear bars among the entire sample , strongly reinforcing the conclusions of other investigators that nuclear bars are not the primary means of transporting this material into the nucleus .
an estimate of the gas density in the nuclear spirals based on extinction measurements suggests that the nuclear spiral dust lanes are probably shocks in nuclear gas disks that are not strongly self - gravitating .
since shocks can dissipate energy and angular momentum , these spiral dust lanes may be the channels by which gas from the host galaxy disks is being fed into the central engines . .
And you have already written the first three sentences of the full article: an important unsolved problem in the study of active galactic nuclei ( agn ) is how the central massive black hole is fueled . in particular ,
if the primary fuel source is interstellar gas and dust in the host galaxy , how is that material transported from kiloparsec scales into the central parsecs of the galaxy and onto the supermassive black hole ? in order to fuel the agn , this material must somehow lose nearly all of its angular momentum .
estimates of the mass accretion rate to power agn range from more than @xmath0 per year for the most luminous quasars to @xmath1 per year for the seyfert galaxies discussed here ..
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thus , over an agn s lifetime ( 10@xmath2 years ? ) a significant amount of material must be transported inwards to feed the central black hole .
a number of dynamical mechanisms have been proposed that could remove angular momentum from the host galaxy s gas and thus supply the fueling rates required to match the observed luminosities of agn .
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10,555 |
Suppose that you have an abstract for a scientific paper: in bulk ferroelectric liquid crystals , the molecular director twists in a helix . in narrow cells , this helix can be unwound by an applied electric field or by boundary effects . to describe helix unwinding as a function of both electric field and boundary effects
, we develop a mesoscale simulation model based on a continuum free energy discretized on a two - dimensional lattice . in these simulations ,
we determine both the director profile across the cell and the net electrostatic polarization . by varying the cell size ,
we show how boundary effects shift the critical field for helix unwinding and lower the saturation polarization .
our results are consistent with experimental data . .
And you have already written the first three sentences of the full article: one of the most extensively studied phases of liquid crystals , both for basic research and for applications , is the smectic - c * ( smc * ) phase of chiral molecules . in this phase ,
the molecules lie in layers and are tilted with respect to the layer normal direction .
the combination of molecular chirality , smectic layering , and tilt order leads to two effects : a ferroelectric polarization within the smectic layer plane and a helical modulation in the orientation of the molecular tilt from layer to layer @xcite ..
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the ferroelectric polarization is useful for display devices , which use an applied electric field to switch the molecular orientation @xcite .
it is also useful for thermal sensors , which measure the temperature variation of the polarization , known as the pyroelectric effect @xcite .
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10,556 |
Suppose that you have an abstract for a scientific paper: we calculate the properties of the two - band hubbard model using the dynamical cluster approximation .
the phase diagram resembles the generic phase diagram of the cuprates , showing a strong asymmetry with respect to electron and hole doped regimes , in agreement with experiment .
asymmetric features are also seen in one - particle spectral functions and in the charge , spin and d - wave pairing susceptibility functions .
we address the possible reduction of the two - band model to a low - energy single - band one , as it was suggested by zhang and rice . comparing the two - band hubbard model properties with the single - band hubbard model ones , we have found similar low - energy physics provided that the next - nearest - neighbor hopping term @xmath0 has a significant value(@xmath1 ) .
the parameter @xmath0 is the main culprit for the electron - hole asymmetry .
however , a significant value of @xmath0 can not be provided in a strict zhang and rice picture where the extra holes added into the system bind to the existing cu holes forming local singlets .
we notice that by considering approximate singlet states , such as plaquette ones , reasonable values of @xmath0 , which capture qualitatively the physics of the two - band model can be obtained .
we conclude that a single - band t - t-u hubbard model captures the basic physics of the cuprates concerning superconductivity , antiferromagnetism , pseudogap and electron - hole asymmetry , but is not suitable for a quantitative analysis or to describe physical properties involving energy scales larger than about 0.5 ev . .
And you have already written the first three sentences of the full article: the theory of the cuprate high temperature superconductors remains one of the most important and daunting problems in condensed matter physics .
the high @xmath2 cuprate superconductors are layered materials with relatively complex structures and chemical composition .
they are highly correlated , with an effective bandwidth roughly equal to the effective local coulomb interaction ..
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the short - range correlations are known to play a paramount role in these materials .
therefore , the dynamical cluster approximation ( dca ) @xcite , which treats short - range correlations explicitly and the long - range physics at the mean - field level , is an ideal tool for the investigation of these systems . a common characteristic all the cuprate materials share is the presence of quasi - two - dimensional @xmath3 planes .
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10,557 |
Suppose that you have an abstract for a scientific paper: the infrared spectrograph ( irs ) is one of three science instruments on the spitzer space telescope .
the irs comprises four separate spectrograph modules covering the wavelength range from 5.3 to 38 with spectral resolutions , @xmath0 and @xmath1 , and it was optimized to take full advantage of the very low background in the space environment .
the irs is performing at or better than the pre - launch predictions .
an autonomous target acquisition capability enables the irs to locate the mid - infrared centroid of a source , providing the information so that the spacecraft can accurately offset that centroid to a selected slit .
this feature is particularly useful when taking spectra of sources with poorly known coordinates .
an automated data reduction pipeline has been developed at the spitzer science center . .
And you have already written the first three sentences of the full article: the design of the irs was driven by the objective of maximizing sensitivity given the 85 cm aperture of the spitzer space telescope @xcite and the then - available detectors .
dividing the optical trains of the irs into four separate spectrographs substantially reduced the complexity and overall cost of the system .
the result is four separate modules , known by their wavelength coverage and resolution as short - low ( sl ) , short - high ( sh ) , long - low ( ll ) , and long - high ( lh ) ..
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the slit widths are set to @xmath2/85 cm , where @xmath3 is the _
wavelength for the module .
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10,558 |
Suppose that you have an abstract for a scientific paper: possibilities of generation of lower order and higher order intermodal entanglement in @xmath0 @xmath1 hyperfine manifold are rigorously investigated using the sen - mandal perturbative technique by showing the equivalence of the system with the four - wave mixing ( fwm ) process .
the investigation has revealed that for a set of experimentally realizable parameters we can observe lower order and higher order intermodal entanglement between pump and signal modes and signal and idler modes in a fwm process associated with the @xmath0 @xmath1 hyperfine manifold .
in addition , trimodal entanglement involving pump , signal and idler modes is also reported . .
And you have already written the first three sentences of the full article: the phenomenon of entanglement has drawn considerable attention since its inception in einstein , podolsky and rosen s ( epr ) thought experiment @xcite .
entanglement describes a system of particles that have one or more highly correlated quantum properties , such as position , momentum , spin , etc .
specifically , two sub - systems that are entangled can not be described by independent wavefunctions ..
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instead the quantum state of the combined system is described by a single wavefunction .
for example , in the initial experiments on entanglement conducted with optical parametric amplifier ( opa ) @xcite , a linear intensity dependence was observed in the coincident absorption probability .
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Suppose that you have an abstract for a scientific paper: we present a measurement protocol for discriminating between two different quantum states of a qubit with high fidelity . the protocol , called _ null value _ , is comprised of a projective measurement performed on the system with a small probability ( also known as partial - collapse ) , followed by a tuned postselection .
we report on an optical experimental implementation of the scheme .
we show that our protocol leads to an amplified signal - to - noise ratio ( as compared with a straightforward strong measurement ) when discerning between the two quantum states .
the notion of `` measurement '' was part of the early framework of quantum mechanics . since early developments ,
the discord between information acquisition on the system and the corresponding disturbance of the system s state became clear .
the contest of obtaining information while keeping minimal disturbance is still an active and vibrant field of study that has branched off into many subtopics . of note and of great practical interest in quantum information processing is the study of quantum state discrimination @xcite .
the ability to optimally discriminate between nonorthogonal quantum states depends on the fidelity of the measurement apparatus and on the amount of prior knowledge one has on the states between which he wants to distinguish .
here we introduce a novel procedure to enhance the discrimination fidelity between two quantum states .
our procedure introduces the notion of quantum measurements with postselection in the field of quantum information processing .
our two - step measurement protocol is related , but differs from , the celebrated weak value ( wv ) measurement protocol , where postselected quantum measurements were first introduced @xcite .
we choose to demonstrate our new approach by focusing on a specific discrimination problem . in conjunction with our theoretical analysis
, we report on experimental results involving classical light , which demonstrate the practicality of our....
And you have already written the first three sentences of the full article: in both the weak value ( wv ) and null value ( nv ) measurement protocols there are two consecutive measurements . generally , using binary detectors ( `` click '' or `` no click '' )
, we would have four possible outcomes at any given attempt : ( `` click '' , `` click '' ) , ( `` click '' , `` no click '' ) , ( `` no click '' , `` click '' ) , ( `` no click '' , `` no click '' ) , where the notation here is ( first measurement outcome , second measurement outcome ) . taking
the outcome of a first weak measurement conditional to a strong second measurement ( i.e. , how the outcome of the first measurement is correlated with the given outcome of the second measurement ) would be proportional to the ( real or imaginary part of the ) standard weak value ( see e.g. , ref ..
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@xcite ) .
a partial - collapse measurement , employed in the nv protocol , is a measurement for which a `` click '' destroys the system .
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10,560 |
Suppose that you have an abstract for a scientific paper: in a magnetic field graphene trilayers support a special multiplet of 12 zero(-energy)-mode landau levels with a threefold degeneracy in landau orbitals .
a close look is made into such zero - mode levels in @xmath0-stacked trilayers , with the coulomb interaction taken into account .
it turns out that the zero - mode landau levels of @xmath0 trilayers are greatly afflicted with electron - hole and valley asymmetries , which come from general hopping parameters and which are enhanced by the coulomb interaction and the associated vacuum effect , the orbital lamb shift , that lifts the zero - mode degeneracy .
these asymmetries substantially affect the way the zero - mode levels evolve , with filling , via coulomb interactions ; and its consequences are discussed in the light of experiments . .
And you have already written the first three sentences of the full article: graphene , an atomic layer of graphite that supports massless dirac fermions , displays remarkable and promising electronic properties .
recently there is increasing interest in bilayers and few layers of graphene , where the physics and applications of graphene become richer , with , e.g. , a tunable band gap @xcite for bilayer graphene .
there are some key signatures of dirac fermions that distinguish graphene from conventional electron systems ..
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( i ) in a magnetic field , graphene supports , as the lowest landau level ( lll ) , a special set of four zero - energy levels differing in spin and valley , as observed via the half - integer quantum hall effect .
( ii ) graphene is an intrinsically many - body system equipped with the valence band acting as the dirac sea .
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10,561 |
Suppose that you have an abstract for a scientific paper: smart grid is an emerging technology which is able to control the power load via price signaling .
the communication between the power supplier and power customers is a key issue in smart grid .
performance degradation like delay or outage may cause significant impact on the stability of the pricing based control and thus the reward of smart grid .
therefore , a qos mechanism is proposed for the communication system in smart grid , which incorporates the derivation of qos requirement and applies qos routing in the communication network . for deriving the qos requirement ,
the dynamics of power load and the load - price mapping are studied .
the corresponding impacts of different qos metrics like delay are analyzed .
then , the qos is derived via an optimization problem that maximizes the total revenue . based on the derived qos requirement ,
a simple greedy qos routing algorithm is proposed for the requirement of high speed routing in smart grid .
it is also proven that the proposed greedy algorithm is a @xmath0-approximation .
numerical simulation shows that the proposed mechanism and algorithm can effectively derive and secure the communication qos in smart grid . .
And you have already written the first three sentences of the full article: in recent years , power grids are experiencing a revolutionary technological transformation .
one significant feature is that electric appliances can receive realtime power price via communication networks and optimize its power consumption level according to the current power price .
then , the power utilization efficiency is significantly improved and the global energy consumption is reduced to combat the crisis of energy resource . in smart grid , a key challenge is how to adapt the communication network to the context of power price transmission ..
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obviously , the data flow of power price can not be elastic since it should be realtime ; otherwise , it may incur a significant loss if the expired power price is used .
therefore , the data transmission of power price must be equipped with quality of service ( qos ) guarantee .
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10,562 |
Suppose that you have an abstract for a scientific paper: the statistical picture of the solution space for a binary perceptron is studied .
the binary perceptron learns a random classification of input random patterns by a set of binary synaptic weights .
the learning of this network is difficult especially when the pattern ( constraint ) density is close to the capacity , which is supposed to be intimately related to the structure of the solution space .
the geometrical organization is elucidated by the entropy landscape from a reference configuration and of solution - pairs separated by a given hamming distance in the solution space .
we evaluate the entropy at the annealed level as well as replica symmetric level and the mean field result is confirmed by the numerical simulations on single instances using the proposed message passing algorithms . from the first landscape ( a random configuration as a reference ) , we see clearly how the solution space shrinks as more constraints are added . from the second landscape of solution - pairs , we deduce the coexistence of clustering and freezing in the solution space . .
And you have already written the first three sentences of the full article: learning in a single layer of feed forward neural network with binary synapses has been studied either based on statistical mechanics analysis @xcite or in algorithmic aspects @xcite .
this network can learn an extensive number @xmath0 of random patterns , where @xmath1 is the number of synapses and @xmath2 denotes the constraint density .
the critical @xmath2 ( also called the capacity ) separating the learnable phase from unlearnable phase is predicted to be @xmath3 where the entropy vanishes @xcite ..
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a solution is defined as a configuration of synaptic weights to implement the correct classification of @xmath4 random input patterns . above @xmath5
, no solutions can be found with high probability ( converging to @xmath6 in the thermodynamic limit ) . the replica symmetric solution presented in ref .
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10,563 |
Suppose that you have an abstract for a scientific paper: following an overview of modeling of ( longitudinal ) multimode semiconductor laser dynamics , we analyze in detail a model proposed in 2006 to explain deterministic , phase - locked modal alternation , experimentally observed a decade ago . through a stability analysis , we prove that the numerically obtained electromagnetic field evolution , interpreted as an explanation of the experiments , is nothing more than an extremely long transient , so long as to be hardly identifiable in an entirely numerical approach . comparison with a model
we have recently derived , which predicts a phase instability ( benjamin - feir - like ) compatible with the experimental observations , highlights the crucial ingredient for the dynamics .
the wide spectrum of unstable eigenvalues accompanying the phase instability plays the role of an equivalent noise in a fully deterministic description , thus reconciling the heuristic models which could qualitatively reproduce the experimental observation either with deterministic equations in the presence of mode - coupling , or through stochastically driven modal decompositions . .
And you have already written the first three sentences of the full article: the dynamics of multimode lasers has occupied a prime place in the investigation of laser behaviour since , starting from their first realizations @xcite , lasers operated on several longitudinal ( and at times transverse ) cavity modes .
indeed , only with further work did it become possible to restrict the operation to one longitudinal and transverse mode oscillation .
thus , questions on the correct modeling of the interaction between several ( longitudinal ) modes and the active medium were vigorously debated very early on ..
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one of the first and most successful proposals for a satisfactory description of laser dynamics came from tang , statz and de mars @xcite who introduced a model
widely used up until today which treats the individual cavity mode intensities as directly coupled to the energy reservoir ( population inversion ) , independently of one another .
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10,564 |
Suppose that you have an abstract for a scientific paper: in a one - dimensional lattice , the induced metric ( from a noncommutative geometry calculation ) breaks translation invariance .
this leads to some inconsistencies among different spectator frames , in the observation of the hoppings of a test particle between lattice sites . to resolve the inconsistencies between the different spectator frames , we replace the test particle s bare mass by an effective locally dependent mass
this effective mass also depends on the lattice constant - i.e. it is a scale dependent variable ( a `` running '' mass ) .
we also develop an alternative approach based on a compensating potential .
the induced potential between a spectator frame and the test particle is attractive on the average .
we then show that the entire formalism holds for a quantum particle represented by a wave function , just as it applies to the mechanics of a classical point particle .
taup-2335 - 96 -1.8 cm -2.2 cm .
And you have already written the first three sentences of the full article: in @xcite it was found that the distances on a one dimensional lattice in a noncommutative geometry differ from their classical analog . in noncommutative geometry the distances on a one dimensional lattice are given by @xmath0 where @xmath1 , @xmath2 , and @xmath3 is the lattice constant , with units of length . as can be seen directly , the distance to an odd @xmath4 point has a unit anomaly , whereas the distance to an even @xmath4 point is the geometric mean of the distances to the two nearby odd points .
moreover , we note that translation invariance is broken , since @xmath5 . in the large @xmath4 limit , however , translation invariance is restored asymptotically .
+ the fact that the distances given by ( eq.[dist ] ) thus break the lattice s translation invariance , represents a new phenomenon of a distance s dependence on reference frames ..
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it follows directly from the basic fact that all the distances in ( eq.[dist ] ) were computed from some zero point , which the lattice sites labeling is been referred to .
the selection of one of the lattice point as the zero point , was done without loss of generality .
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Suppose that you have an abstract for a scientific paper: an information - geometric approach to sensor management is introduced that is based on following geodesic curves in a manifold of possible sensor configurations .
this perspective arises by observing that , given a parameter estimation problem to be addressed through management of sensor assets , any particular sensor configuration corresponds to a riemannian metric on the parameter manifold . with this perspective ,
managing sensors involves navigation on the space of all riemannian metrics on the parameter manifold , which is itself a riemannian manifold .
existing work assumes the metric on the parameter manifold is one that , in statistical terms , corresponds to a jeffreys prior on the parameter to be estimated .
it is observed that informative priors , as arise in sensor management , can also be accommodated . given an initial sensor configuration , the trajectory along which to move in sensor configuration space to gather most information is seen to be locally defined by the geodesic structure of this manifold .
further , divergences based on fisher and shannon information lead to the same riemannian metric and geodesics . information geometry ; sensor management .
And you have already written the first three sentences of the full article: the work of amari and others @xcite on the use of methods of riemannian geometry to analyze statistical estimation problems is of increasing interest to researchers in signal processing .
this methodology , known as _ information geometry _ , provides a rigorous framework for measuring the power of data to discriminate values of parameters .
these ideas date back to rao @xcite , who showed that the fisher information of a likelihood used in an estimation problem can be seen as a riemannian metric on the parameter manifold ..
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this paper brings an information - geometric perspective to a class of sensor management problems by casting the objective of sensor management as parameter estimation and describing how this leads to the role of sensor management as selecting a riemannian metric for the parameter manifold .
established results in riemannian geometry @xcite , outside the context of information geometry , show that the collection of all riemannian metrics on a riemannian manifold is itself an ( infinite - dimensional ) riemannian manifold . in problems where the collection of possible sensor actions is suitably modeled by a smooth finite - dimensional manifold , the space of interest is a finite - dimensional sub - manifold of this infinite - dimensional riemannian manifold .
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10,566 |
Suppose that you have an abstract for a scientific paper: we present a comprehensive set of optical and near - infrared photometric and spectroscopic observations for sn 2014ck , extending from pre - maximum to six months later .
these data indicate that sn 2014ck is photometrically nearly identical to sn 2002cx , which is the prototype of the class of peculiar transients named sne iax .
similar to sn 2002cx , sn 2014ck reached a peak brightness @xmath0 mag , with a post - maximum decline - rate @xmath1 mag .
however , the spectroscopic sequence shows similarities with sn 2008 ha , which was three magnitudes fainter and faster declining . in particular , sn 2014ck exhibits extremely low ejecta velocities , @xmath2 km s@xmath3 at maximum , which are close to the value measured for sn 2008 ha and half the value inferred for sn 2002cx .
the bolometric light curve of sn 2014ck is consistent with the production of @xmath4 of @xmath5ni .
the spectral identification of several iron - peak features , in particular co ii lines in the nir , provides a clear link to sne ia .
also , the detection of narrow si , s and c features in the pre - maximum spectra suggests a thermonuclear explosion mechanism .
the late - phase spectra show a complex overlap of both permitted and forbidden fe , ca and co lines .
the appearance of strong [ ca ii ] @xmath67292 , 7324 again mirrors the late - time spectra of sn 2008 ha and sn 2002cx .
the photometric resemblance to sn 2002cx and the spectral similarities to sn 2008 ha highlight the peculiarity of sn 2014ck , and the complexity and heterogeneity of the sne iax class .
[ firstpage ] supernovae : general supernovae : individual : sn 2014ck , sn 2006fp galaxies : individual : ugc 12182 .
And you have already written the first three sentences of the full article: the discovery of several peculiar type ia supernovae ( sne ia ) has drawn the attention both to the photometric and spectroscopic diversity among this class of otherwise homogeneous transients .
the dispersion of the luminosity decline rate relation @xcite can be explained by an additional correlation between the decline rate and the colour at maximum light @xcite .
hence sne ia can be arranged into a photometric sequence extending from luminous , blue , slowly declining sn ia , like sn 1991 t , to normal events @xcite , and finally to sub - luminous , red , quickly declining objects , like sn 1991bg @xcite ..
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sne ia also appear to form a spectroscopic sequence based on the systematic variations in the flux ratios of several spectral features near maximum light ( e.g. si ii @xmath65972 , 6355 , see * ? ? ?
the common view is , despite their diversity , peculiar events such as the luminous 1991t - like and sub - luminous 1991bg - like sne ia , just like the normal population of sne ia , originate from the thermonuclear explosion of a c / o white dwarf ( wd ) that exceeds the chandrasekhar mass after accreting mass from a companion star in a binary system . however , there is a group of peculiar sne ia that challenges the canonical chandrasekhar - mass explosion channel .
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Suppose that you have an abstract for a scientific paper: we have extended the semi - classical theory to include a general account of matrix valued hamiltonians , i.e. those that describe quantum systems with internal degrees of freedoms , based on a generalization of the gutzwiller trace formula for a @xmath0 dimensional hamiltonian @xmath1 .
the classical dynamics is governed by @xmath2 hamilton - jacobi ( hj ) equations , that act in a phase space endowed with a classical berry curvature encoding anholonomy in the parallel transport of the eigenvectors of @xmath3 ; which describe the internal structure of the semi - classical particles .
this berry curvature is a fully classical object and is , in that sense , as fundamental to the semi - classical theory of matrix hamiltonians as the hamilton - jacobi equations . at the @xmath4 level
, it results in an additional semi - classical phase composed of ( i ) a berry phase and ( ii ) a dynamical phase resulting from the classical particles `` moving through the berry curvature '' .
we show that the dynamical part of this semi - classical phase will , generally , only be zero only for the case in which the berry phase is topological ( i.e. depends only on the winding number ) .
we illustrate the method by calculating the landau spectrum for monolayer graphene , the four - band model of ab bilayer graphene , and for a more complicated matrix hamiltonian describing the silicene band structure .
finally we apply our method to an inhomogeneous system consisting of a strain engineered one dimensional moir in bilayer graphene , finding localized states near the dirac point that arise from electron trapping in a semi - classical moir potential
. the semi - classical density of states of these localized states we show to be in perfect agreement with an exact quantum mechanical calculation of the density of states . .
And you have already written the first three sentences of the full article: in the @xmath5 limit the behaviour of quantum systems can be expressed in terms of the classical phase space trajectories .
for one dimensional scalar problems the wkb method @xcite yields semi - classical wavefunctions and energy levels , an approach that can be generalized to both integrable multi - dimensional systems ( ekb torus quantization @xcite ) , as well as to systems with multi - component wave functions@xcite . in the latter case , however , the multi - component wavefunction matching inherent in the wkb approach rapidly becomes prohibitively cumbersome as the number of components increases .
the gutzwiller trace formula circumvents this matching problem by giving a direct expression for the semi - classical density of states ..
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it is , furthermore , valid for systems with a non - integrable ( i.e. , chaotic ) classical limit .
while generalizations of the trace formula for the multi - component case have been presented for specific matrix hamiltonians such as the relativistic dirac hamiltonian@xcite and the dirac - weyl hamiltonian of graphene@xcite , a general multi - component version of the trace formula has not been considered . in the solid state theory context , however , a semi - classical method applicable to _ arbitrary matrix hamiltonians _ would be extremely useful .
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10,568 |
Suppose that you have an abstract for a scientific paper: hamiltonian dynamics of a thin vortex filament in ideal incompressible fluid near a flat fixed boundary is considered at the conditions that at any point of the curve determining shape of the filament the angle between tangent vector and the boundary plane is small , also the distance from a point on the curve to the plane is small in comparison with the curvature radius .
the dynamics is shown to be effectively described by a nonlinear system of two ( 1 + 1)-dimensional partial differential equations .
the hodograph transformation reduces that system to a single linear differential equation of the second order with separable variables .
simple solutions of the linear equation are investigated at real values of spectral parameter @xmath0 when the filament projection on the boundary plane has shape of a two - branch spiral or a smoothed angle , depending on the sign of @xmath0 . .
And you have already written the first three sentences of the full article: it is a well known fact that solutions of equations determining the motion of a homogeneous inviscid fluid possess a remarkable property the lines of the vorticity field are frozen - in @xcite .
mathematical reason for this is the so called relabeling symmetry of fluids that provides necessary conditions for the noether theorem applicability and results in infinite number of the conservation laws @xcite . due to this basic property , in the framework of ideal hydrodynamics
such flows are possible where during sufficiently long time interval the vorticity is concentrated in quasi - one - dimensional structures , vortex filaments , that fill a small part of entire bulk of the fluid ..
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the motion of vortex filaments is very interesting problem both from theoretical and practical viewpoints and is a classical subject of hydrodynamics ( see , for instance , @xcite and references therein for various analytical and numerical approaches to this problem ) . in general case analytical study in this field is highly complicated because of several reasons , the main of them being non - locality and nonlinearity of governing equations of motion .
a less significant trouble seems to be the necessity of some regularization procedure for the hamiltonian functional ( the total energy ) of the system in the limit of `` infinitely thin '' vortex filaments , since a logarithmic divergency takes place in some observable physical quantities ( for instance , in the velocity of displacement of curved pieces of the filament ) as the thickness decreases .
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Suppose that you have an abstract for a scientific paper: a supersymmetric field theory of light diffusion in semi - infinite disordered media is presented . with the help of this technique
we justify at the perturbative level the local light diffusion proposed by tiggelen , lagendijk , and wiersma [ phys .
rev .
lett . * 84 * , 4333 ( 2000 ) ] , and show that the coherent backscattering line shape of medium bar displays a crossover from two - dimensional weak to quasi - one - dimensional strong localization . .
And you have already written the first three sentences of the full article: the anderson localization of light has been one of the most fascinating phenomena in condensed matter physics since the mid - eighties @xcite . like electron systems this phenomenon finds its origin in coherent multiple scattering which slows down diffusion of photons and eventually brings them to stop .
parallel to studies of disordered conductors the subject in this field ranges from light localization near or far below the mobility edge in bulk ( infinite ) systems @xcite ( where low - energy photon motion enjoys the translational symmetry ) to their detection such as transmission measurements in the slab geometry ( e.g. , refs . ) .
a unique subject of localization in optical ( and other classical wave ) systems is the enhanced coherent backscattering ( cbs ) phenomenon @xcite . in this subject.
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the issue of semi - infinite geometry is heavily addressed because the cbs line shape is responsible for by optical paths near the vacuum - medium interface .
although it is well known that in the weak disorder region , i.e. , @xmath0 ( @xmath1 the mean free path and @xmath2 the wavelength ) incident photons enjoy diffusion as in bulk media @xcite , in the strong disorder region @xmath3 the role played by the leakage at the interface has been of long term interests @xcite and , still , remains in the central position of cbs studies , particularly to forecast or observe the cbs line shape @xcite .
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10,570 |
Suppose that you have an abstract for a scientific paper: we present a line - based model of transverse domain walls in thin magnetic strips , to study the effect of bulk disorder on the domain wall dynamics within the thermally activated creep regime .
the creep velocity is found to exhibit a non - linear dependence on both applied magnetic fields and electric currents , characterized by similar creep exponents for both forms of the external drive .
we discuss briefly the significance of the inherently stochastic thermally activated domain wall motion from the point of view of spintronics applications , where it generally is essential to be able to control the domain wall displacement in a deterministic manner . .
And you have already written the first three sentences of the full article: wall dynamics in thin magnetic strips or wires driven by either applied external magnetic fields or electric currents has been an active field of research during recent years , due to both the fundamental aspects of the underlying physics as well as due to the potential spintronics applications @xcite .
most of the theoretical studies of such phenomena have so far focused on `` perfect '' systems free of any imperfections in the sample that could affect the dynamics of the domain wall .
however , disorder is present in practically any realistic material , either in the form of edge roughness or various point - like defects in the bulk of the system ..
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while the effect of edge roughness @xcite or notches @xcite on domain wall motion has received much attention in the literature , bulk disorder is usually assumed to be insignificant in narrow nanostrips .
however , this might not be true in general : for instance , thickness fluctuations of the strip might give rise to bulk disorder similarly to the disorder due to the rough edges of the system . also
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10,571 |
Suppose that you have an abstract for a scientific paper: we present the first three - dimensional ( 3d ) magnetohydrodynamic ( mhd ) simulations of the atmosphere of hd209458b which self - consistently include reduction of winds due to the lorentz force and ohmic heating .
we find overall wind structures similar to that seen in previous models of hot jupiter atmospheres , with strong equatorial jets and meridional flows poleward near the dayside and equatorward near the night .
inclusion of magnetic fields slows those winds and leads to ohmic dissipation .
we find wind slowing ranging from 10 - 40% for reasonable field strengths .
we find ohmic dissipation rates @xmath0w at 100 bar , orders of magnitude too small to explain the inflated radius of this planet .
faster wind speeds , not achievable in these anelastic calculations , may be able to increase this value somewhat , but likely wo nt be able to close the gap necessary to explain the inflated radius .
we demonstrate that the discrepancy between the simulations presented here and previous models is due to inadequate treatment of magnetic field geometry and evolution
. induced poloidal fields become much larger than those imposed , highlighting the need for a self - consistent mhd treatment of these hot atmospheres . .
And you have already written the first three sentences of the full article: the field of extrasolar planet research is growing rapidly with more than 1000 planets found ( as of november , 2013 ) .
many of these objects are large and/or close to their host star .
these large extrasolar planets have come to be known as extra - solar giant planets ( egps ) and those in close proximity to their host stars are often referred to as `` hot jupiters '' ..
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many of these planets are observed to transit their host stars as viewed from earth . combined with radial velocity data ,
this allows calculation of the planetary mass , radius and surface gravity . and
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10,572 |
Suppose that you have an abstract for a scientific paper: utilizing high - resolution cosmological hydrodynamic simulations we investigate various ultra - violet absorption lines in the circumgalactic medium of star forming galaxies at low redshift , in hopes of checking and alleviating the claimed observational conundrum of the ratio of nv to ovi absorbers , among others .
we find a satisfactory agreement between simulations and extant observational data with respect to the ratios of the following four line pairs examined , nv / ovi , siiv / ovi , niii / ovi and nii / ovi . for the pairs involving nitrogen lines , we examine two cases of nitrogen abundance , one with constant n / o ratio and the other with varying n / o ratio , with the latter motivated by theoretical considerations of two different synthetic sources of nitrogen that is empirically verified independently . along a separate vector , for all line pairs , we examine two cases of radiation field , one with the haardt - madau background radiation field and the other with an additional local radiation field sourced by hot gas in the host galaxy . in all cases ,
two - sample kolmogorov - smirnov tests indicate excellent agreements .
we find that the apparent agreements between simulations and observations will be strongly tested , if the bulk of current upper limits of various line ratios are turned into actual detections .
we show that an increase in observational sensitivity by @xmath0 dex will already start to significantly constrain the models .
= 1 .
And you have already written the first three sentences of the full article: the nature of halo gas ( a.k.a .
circumgalactic medium ; cgm hereafter ) , on galactocentric distances of @xmath1 kpc , is a problem of significant ongoing interest in galaxy formation .
halo gas links galaxies from the intergalactic medium and is the conduit for exchange of matter energy density , momentum , angular momentum and metals between star formation and active galactic nucleus induced outflow and gravitational inflow of gas ..
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thus , understanding halo gas is imperative before a satisfactory theory of galaxy formation and evolution may be constructed .
there has been recent rapid advances on the observational front to address this important issue , made possible primarily by hst observations ( e.g. , * ? ? ?
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10,573 |
Suppose that you have an abstract for a scientific paper: we associate to each synchronous game an algebra whose representations determine if the game has a perfect deterministic strategy , perfect quantum strategy or one of several other strategies . when applied to the graph coloring game , this leads to characterizations in terms of properties of an algebra of various quantum chromatic numbers that have been studied in the literature .
this allows us to develop a correspondence between various chromatic numbers of a graph and ideals in this algebra which can then be approached via grbner basis methods . .
And you have already written the first three sentences of the full article: given a graph @xmath0 and a natural number @xmath1 , there is a game called the _ c - coloring game _ of @xmath0 and it is known that there is a perfect deterministic strategy for this game if and only if @xmath0 has a c - coloring . thus , the _ chromatic number _ of @xmath0 , @xmath2 can be characterized as the least integer for which a perfect deterministic strategy exists for the c - coloring game .
this led researchers to consider various kinds of probabilistic strategies for games , especially cases where the probabilities arose from the random outcomes of quantum experiments that were in finite dimensional entangled states , called _
quantum strategies_. the least @xmath1 for which the c - coloring game has such a perfect strategy became known as the _ quantum chromatic _ number of a graph , denoted @xmath3 . for an introduction to this literature ,.
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see @xcite , @xcite .
there are some open questions about the proper model for the set of probabilities that arise from entangled quantum experiments and this has led to the study of several , potentially different , definitions of quantum chromatic numbers denoted @xmath4 and @xmath5 , see @xcite and @xcite .
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10,574 |
Suppose that you have an abstract for a scientific paper: we present for numerical use the analytic continuations to complex arguments of those basic mellin transforms , which build the harmonic sums contributing to the 3loop anomalous dimensions .
eight new basic functions contribute in addition to the analytic continuations for the 2loop massless wilson coefficients calculated previously .
the representations derived have a relative accuracy of better than @xmath0 in the range @xmath1 $ ] .
desy 05007 + sfb / cpp0505 + march 2005 + * analytic continuation of the harmonic sums * + * for the 3loop anomalous dimensions * + johannes blmlein and sven - olaf moch + _ platanenallee 6 , d-15735 zeuthen , germany _ + .
And you have already written the first three sentences of the full article: a very efficient way to calculate the evolution of the parton densities in deeply inelastic scattering consist in solving the evolution equations in mellin@xmath2 space @xcite . with the advent of the 3loop anomalous dimensions
@xcite the scaling violations of the deep
inelastic structure functions can be analyzed at high precision ..
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the evolution equations are ordinary differential equations , which can be solved analytically .
the wilson coefficients @xcite and anomalous dimensions are given in terms of multiple nested harmonic sums @xcite , which obey algebraic relations @xcite .
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10,575 |
Suppose that you have an abstract for a scientific paper: we have made the first measurement of the @xmath0 width using 9/fb of @xmath1 data collected near the @xmath2 resonance by the cleo ii.v detector .
our method uses advanced tracking techniques and a reconstruction method that takes advantage of the small vertical size of the cesr beam spot to measure the energy release distribution from the @xmath3 decay .
our preliminary result is @xmath4 kev .
cleo conf 01 - 2 + * first measurement of @xmath5 * + cleo collaboration + ( february 5 , 2001 ) t. e. coan,@xmath6 v. fadeyev,@xmath6 y. s. gao,@xmath6 y. maravin,@xmath6 i. narsky,@xmath6 r. stroynowski,@xmath6 j. ye,@xmath6 t. wlodek,@xmath6 m. artuso,@xmath7 c. boulahouache,@xmath7 k. bukin,@xmath7 e. dambasuren,@xmath7 g. majumder,@xmath7 r. mountain,@xmath7 s. schuh,@xmath7 t. skwarnicki,@xmath7 s. stone,@xmath7 j.c .
wang,@xmath7 a. wolf,@xmath7 j. wu,@xmath7 s. kopp,@xmath8 m. kostin,@xmath8 a. h. mahmood,@xmath9 s. e. csorna,@xmath10 i. danko,@xmath10 v. jain,@xmath11 k. w. mclean,@xmath10 z. xu,@xmath10 r. godang,@xmath12 g. bonvicini,@xmath13 d. cinabro,@xmath13 m. dubrovin,@xmath13 s. mcgee,@xmath13 g. j. zhou,@xmath13 a. bornheim,@xmath14 e. lipeles,@xmath14 s. p. pappas,@xmath14 a. shapiro,@xmath14 w. m. sun,@xmath14 a. j. weinstein,@xmath14 d. e. jaffe,@xmath15 r. mahapatra,@xmath15 g. masek,@xmath15 h. p.
paar,@xmath15 d. m. asner,@xmath16 a. eppich,@xmath16 t. s. hill,@xmath16 r. j. morrison,@xmath16 r. a. briere,@xmath17 g. p. chen,@xmath17 t. ferguson,@xmath17 h. vogel,@xmath17 a. gritsan,@xmath18 j. p.
alexander,@xmath19 r. baker,@xmath19 c. bebek,@xmath19 b. e. berger,@xmath19 k. berkelman,@xmath19 f. blanc,@xmath19 v. boisvert,@xmath19 d. g. cassel,@xmath19 p. s. drell,@xmath19 j. e. duboscq,@xmath19 k. m. ecklund,@xmath19 r. ehrlich,@xmath19 p. gaidarev,@xmath19 l. gibbons,@xmath19 b. gittelman,@xmath19 s. w. gray,@xmath19 d. l. hartill,@xmath19 b. k. heltsley,@xmath19 p. ....
And you have already written the first three sentences of the full article: a measurement of @xmath5 opens an important window on the non - perturbative strong physics involving heavy quarks .
the basic framework of the theory is well understood , however , there is still much speculation - predictions for the width range from @xmath34 to @xmath35 @xcite .
we know the @xmath0 width is dominated by strong decays since the measured electromagnetic transition rate is small , @xmath36% @xcite ..
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the level splitting in the @xmath37 sector is not large enough to allow real strong transitions .
therefore , a measurement of the width of the @xmath0 gives unique information about the strong coupling constant in heavy - light systems .
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10,576 |
Suppose that you have an abstract for a scientific paper: we study the configurational properties of single polymers in a theta solvent by monte carlo simulation of the bond fluctuation model .
the intramolecular structure factor at the theta point is found to be distinctively different from that of the ideal chain .
the structure factor shows a hump around @xmath0 and a dip around @xmath1 in the kratky plot with @xmath2 being the radius of gyration .
this feature is apparently similar to that in a melt .
the theoretical expression by the simple perturbation expansion to the first order in terms of the mayer function can be fitted to the obtained structure factor quite well , but the second virial coefficient can not be set to zero . .
And you have already written the first three sentences of the full article: one of the basic premises in the polymer physics is that the bonds connecting neighboring monomer units are uncorrelated beyond the persistent length along the chain @xcite .
this property allows us to consider only a flexible chain as long as we are interested in large scale properties of a polymer chain that is much longer than its persistent length . in this sense , it was a little embarrassing to realize that there is actually a long range correlation in the bond orientation of a polymer chain , and that the bond - bond correlation function decays not exponentially but as the power law @xcite .
the traditional picture for the bond - bond correlation is based on a simple calculation for the polymer with a fixed bond angle around freely rotating bonds . in this case.
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, one can calculate the bond - bond correlation function explicitly to show the exponential decay with a persistent length @xcite .
the existence of the long range correlation , however , has been pointed out @xcite , and it was demonstrated recently that the power law behavior is induced in the bond - bond correlation through the interaction between monomers separated by a long distance in the curvilinear coordinate along the chain @xcite .
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10,577 |
Suppose that you have an abstract for a scientific paper: given in the title are two algorithms to compute the extreme eigenstate of a high - dimensional hermitian matrix using the tensor train ( tt ) / matrix product states ( mps ) representation .
both methods empower the traditional alternating direction scheme with the auxiliary ( e.g. gradient ) information , which substantially improves the convergence in many difficult cases .
being conceptually close , these methods have different derivation , implementation , theoretical and practical properties .
we emphasize the differences , and reproduce the numerical example to compare the performance of two algorithms . _
keywords : _ high dimensional problems , dmrg , mps , tensor train format , extreme eigenstate .
_ msc : _
15a18 , 15a69 , 65f10 , 65f15 , 82b28 , 82b20 _ pacs : _
02.10.xm , 02.60.dc , 75.10.pq , 05.10.cc .
And you have already written the first three sentences of the full article: actual problems of science , engineering and society can be so complex , that their mathematical portrait requires more than three dimensions .
quantum world gives us a perfect example of essentially high dimensional systems , described by a joint wavefunction ( or density matrix ) of all particles .
a simple system of @xmath0 spin-@xmath1 particles is an entanglement of @xmath2 possible states , and should be described by the same amount of numbers , which creates out - of - memory errors on a typical workstation for @xmath3 even with a brute force of modern supercomputers , standard numerical methods can not honestly simulate protein - size molecules ( @xmath4 @xmath5 ) , since the complexity and storage explode exponentially with @xmath6 to overcome this problem , known as the _ curse of dimensionality _ , we use data - sparse representations for high - dimensional vectors and matrices , and develop special algorithms to work with them . proposed in 1992 , the _ density matrix renormalization group _ ( dmrg ) algorithm @xcite and the _ matrix product states _ ( mps ) formalism @xcite suggest to represent a wavefunction @xmath7 in the following tensor - product form @xmath8 in numerical linear algebra this format was re - discovered as the _ tensor train _ ( tt ) decomposition @xcite . a single tt core ( or _ site _ ) @xmath9 $ ] is described by @xmath10 numbers , where @xmath11 denotes the number of possible states for the @xmath12th particle ( the _ mode size _ ) , and @xmath13 is the tt rank ( or _ bond dimension _ ) ..
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the total number of representation parameters scales as @xmath14 @xmath15 @xmath16 and is feasible for computations with @xmath17 to the dmrg algorithm was originally proposed to find the _ ground state _ , i.e. the minimal eigenpair of a hermitian matrix @xmath18 this problem is equivalent to the minimization of the rayleigh quotient @xmath19 substituting @xmath20 with @xmath21 and applying the same algorithm , we can solve linear systems @xmath22 with hermitian positive definite matrix @xcite .
this framework can be extended to a broad class of problems .
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10,578 |
Suppose that you have an abstract for a scientific paper: we study the degree of success of a single predator hunting a herd of prey on a two dimensional square lattice landscape .
we explicitly consider the self volume of the prey restraining their dynamics on the lattice .
the movement of both predator and prey is chosen to include an intelligent , decision making step based on their respective sighting ranges , the radius in which they can detect the other species ( prey can not recognise each other besides the self volume interaction ) : after spotting each other the motion of prey and predator turns from a nearest neighbour random walk into direct escape or chase , respectively .
we consider a large range of prey densities and sighting ranges and compute the mean first passage time for a predator to catch a prey as well as characterise the effective dynamics of the hunted prey .
we find that the prey s sighting range dominates their life expectancy and the predator profits more from a bad eyesight of the prey than from his own good eye sight .
we characterise the dynamics in terms of the mean distance between the predator and the nearest prey .
it turns out that effectively the dynamics of this distance coordinate can be captured in terms of a simple ornstein - uhlenbeck picture . reducing the many - body problem to a simple two - body problem by imagining predator and nearest prey to be connected by a hookean bond , all features of the model such as prey density and sighting ranges merge into the effective binding constant . .
And you have already written the first three sentences of the full article: every animal must eat in order to survive . for certain predator species this necessarily implies to chase and bring down a sufficient amount of prey .
with predators always on the lookout for food , prey must constantly be on the alert . while scattering and zigzagging to confuse the predator is a popular method of herd animals to escape @xcite , if the escape paths are not well co - ordinated individual prey
may also block each other ..
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the self volume effect is also relevant in the hunt of killer cells ( macrophages , for instance ) in biological organisms attacking bacteria colonies or biofilms . in this paper
we study the influence of self volume effects on a herd of non - communicating prey with the autonomy of taking decisions on the run , as quantified by the typical time to catch a prey . in the study of the dynamics of predator - prey systems
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10,579 |
Suppose that you have an abstract for a scientific paper: a wide range of natural and engineered phenomena rely on large networks of interacting units to reach a dynamical consensus state where the system collectively operates . here
we study the dynamics of self - organizing systems and show that for generic directed networks the collective frequency of the ensemble is _ not _ the same as the mean of the individuals natural frequencies .
specifically , we show that the collective frequency equals a weighted average of the natural frequencies , where the weights are given by an out - flow centrality measure that is equivalent to a reverse pagerank centrality .
our findings uncover an intricate dependence of the collective frequency on both the structural directedness and dynamical heterogeneity of the network , and also reveal an unexplored connection between synchronization and pagerank , which opens the possibility of applying pagerank optimization to synchronization .
finally , we demonstrate the presence of collective frequency variation in real - world networks by considering the uk and scandinavian power grids . .
And you have already written the first three sentences of the full article: the emergence of synchronization in ensembles of dynamical units is a universal phenomenon that is vital to the functionality of many natural and man - made systems @xcite .
in addition to the ability of the individuals that make up such systems to operate in unison , in many instances the particular frequency or velocity with which they evolve is crucial .
for example , the sources and loads that make up power grids must reach consensus to avoid power failures , but reaching a common frequency alone is not enough ; the system is most efficient near a certain reference frequency of approximately @xmath0 - @xmath1 hz , and may fail if the collective dynamics are too far from this range @xcite . in a wide variety of disciplines , from biology and neuroscience to mechanical and electrical engineering.
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, there are vital systems whose functionality is jeopardized if the collective frequency or velocity differs too much from a given reference frequency ; examples include brain dynamics , cardiac excitation , consensus networks , and coordination of muscle movements in the digestive track @xcite . in the case of cardiac excitation , for instance
, rapid oscilations can give rise to dynamical instabilities that often precede ventricular fibrillation and eventually heart failure .
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10,580 |
Suppose that you have an abstract for a scientific paper: we analysed rxte data of sco x-1 which show khz quasi - periodic oscillations ( qpos ) and the @xmath068 hz normal - branch oscillation ( nbo ) simultaneously . using power spectra of 0.030.5 s data segments
, we find that both the upper khz qpo frequency @xmath1 and the ratio of lower to upper khz qpo amplitude are anticorrelated to variations in the x - ray count - rate taking place on the nbo time scale .
the frequency dependence is similar to ( but probably weaker than ) that found on longer time scales , but the power ratio dependence is _ opposite _ to it .
a model where radiative stresses on the disk material , modulated at the nbo frequency , lead to changes in @xmath1 can explain the data ; this implies some of the nbo flux changes originate from inside the inner disk radius .
we discuss how these findings affect our understanding of khz qpos and of the low - frequency variability of low - mass x - ray binaries . .
And you have already written the first three sentences of the full article: observations with the rossi x - ray timing explorer ( rxte ) of neutron - star low - mass x - ray binaries ( lmxbs ) have led to the discovery of kilohertz quasi - periodic oscillations ( khz qpos ) in about 20 sources ( van der klis 2000 for a review ) .
the khz qpo frequency is always correlated with position in the tracks traced out by these sources in x - ray color - color diagrams .
this usually implies khz qpo frequency is correlated with x - ray count rate , but anticorrelation also occurs ( wijnands et al ..
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1997 , homan et al .
2001 , this paper ) . on time scales
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10,581 |
Suppose that you have an abstract for a scientific paper: the transition radiation detector ( trd ) for the alice experiment at the large hadron collider ( lhc ) identifies electrons in p+p and in the challenging high multiplicity environment of heavy - ion collisions and provides fast online tracking for the alice level1 trigger .
the trd is designed to have excellent position resolution and pion rejection capability .
presently , six of the 18 trd supermodules are installed in the alice central barrel . in 2008 ,
four supermodules were installed and commissioning of the detector using cosmic ray tracks was successfully performed .
we briefly describe the design of the detector and report on the performance and current understanding of the detector based on these data . .
And you have already written the first three sentences of the full article: alice ( a large ion collider experiment ) is a general - purpose heavy - ion experiment designed to study the physics of strongly interacting matter and the quark - gluon plasma in nucleus - nucleus collisions at the lhc @xcite .
it will study the global properties with hadron production and correlations , and probe the properties of the medium with the collision products such as heavy quarkonia , open charm and beauty , light vector mesons , thermal leptons , direct-@xmath0 , jets and high-@xmath1 hadrons .
one of the powerful probes of the created qcd medium is heavy quarkonia , whose suppression or enhancement @xcite is sensitive to the screening of color charge due to deconfinement and to statistical recombination ..
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thus measurements of leptons from their decay are crucial .
an important task of the transition radiation detector ( trd ) for the alice experiment is to supplement the time projection chamber ( tpc ) electron / pion identification by a pion rejection factor of the order of 100 at momenta in excess of 1 gev / c .
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10,582 |
Suppose that you have an abstract for a scientific paper: we study the color - dependent confining forces between two quarks by the quenched lattice simulations of coulomb gauge qcd .
the color - singlet and color - antitriplet instantaneous potentials yield attractive forces .
the ratio of the string tensions obtained from them is approximately 2 and have little volume dependence .
meanwhile , the color - octet and color - sextet channels give a minor contribution for two - quark system .
we finally find that the infrared self - energy of the color - nonsinglet channels diverges in the infinite volume limit ; however , the degree of the divergence on the finite lattice can be understood in terms of color factors . .
And you have already written the first three sentences of the full article: the long - distance color - dependent forces among quarks and gluons are the key quantities for the understanding of the internal structure of hadron as well as color confinement dynamics .
the quarks and gluons are described in the quantum chromodynamics ( qcd ) , and have a color charge based on the su(3 ) group , with which the quark combination yields many color - dependent forces including both attractive and repulsive forces .
they make the hadron structure ( quark bound state ) more complicated ..
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therefore , it is essential to know the basic behavior of the color - dependent force at short and large distances
. the color - dependent force will be important when one investigates the multiquark hadron ( made of more than four quarks ) and the exotic meson , etc .
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10,583 |
Suppose that you have an abstract for a scientific paper: the structures of the ground and excited states of @xmath0be were studied with antisymmetrized molecular dynamics .
the ground state was found to be a state with a developed 2@xmath1 core with two neutrons occupying the intruder orbits .
the energy levels of the newly measured spin - assigned states were described well , except for the @xmath2 state .
the calculations indicated that many exotic cluster structures appear in the low - energy region .
the widths concerning @xmath1 and @xmath3he decays were discussed by using reduced width amplitudes . .
And you have already written the first three sentences of the full article: owing to the progress of experimental techniques , information concerning the excited states of light unstable nuclei has rapidly increased .
recently , exotic clustering in the light unstable nuclei has become one of the attractive subjects in 3experimental and theoretical research . since
, in light stable nuclei , it has already been known that clustering is one of the essential features of nuclear dynamics , not only in excited states , but also in ground states , it is natural to expect cluster features in light unstable nuclei ..
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pioneering theoretical studies have suggested the development of cluster structures with a 2@xmath1 core in be and b isotopes @xcite . especially , highly excited states with developed cluster structures in @xmath4be and @xmath5be have been studied by microscopic calculations @xcite . in the case of @xmath0be , the existence of cluster states was suggested in experimental measurements of the excited states @xcite . in recent experiments of @xmath3he+@xmath3he and @xmath6he+@xmath7he breakup reactions @xcite ,
many new excited states were discovered above the threshold energies .
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10,584 |
Suppose that you have an abstract for a scientific paper: among other things , we prove the following two topologcal statements about closed hyperbolic @xmath0-manifolds . first , every rational second homology class of a closed hyperbolic @xmath0-manifold has a positve integral multiple represented by an oriented connected closed @xmath1-injectively immersed quasi - fuchsian subsurface .
second , every rationally null - homologous , @xmath1-injectively immersed oriented closed @xmath2-submanifold in a closed hyperbolic @xmath0-manifold has an equidegree finite cover which bounds an oriented connected compact @xmath1-injective immersed quasi - fuchsian subsurface . in part , we exploit techniques developed by kahn and markovic in @xcite , but we only distill geometric and topological ingredients from those papers so no hard analysis is involved in this paper . .
And you have already written the first three sentences of the full article: in this paper , we are concerned about the construction problem of homologically interesting connected quasi - fuchsian subsurfaces in closed hyperbolic @xmath0-manifolds .
we show that in a closed hyperbolic @xmath0-manifold , it is always possible to construct an oriented compact connected @xmath1-injectively immersed quasi - fuchsian subsurface which is virtually bounded by prescribed multicurves and which virtually represents a prescribed rational relative second homology class ( theorem [ main - qfsurface ] ) .
the following two results are motivational special cases of theorem [ main - qfsurface ] . for simplicity we state them first ..
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[ qfsurfaceclosed ] every rational second homology class of a closed hyperbolic @xmath0-manifold has a positve integral multiple represented by an oriented connected closed @xmath1-injectively immersed quasi - fuchsian subsurface .
[ qfsurfaceboundary ] every rationally null - homologous , @xmath1-injectively immersed oriented closed @xmath2-submanifold in a closed hyperbolic @xmath0-manifold has an equidegree finite cover which bounds an oriented connected compact @xmath1-injective immersed quasi - fuchsian subsurface . here
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10,585 |
Suppose that you have an abstract for a scientific paper: generalizing one of the author s recent paper on minimal higgs inflation , we proposed and analyzed a large class of inflationary models with non - polynomial modification of the potential .
the modification is done by introducing a single scale creating an infinite plateau for large inflaton field value .
one can identify those class of potentials as a small dip at the origin of a constant one dimensional field space . because of this large flat plateau , we find all the predictions are fitting extremely well with the recent observations made by planck .
we have extensively studied perturbative reheating phenomena specifically focusing on the production of dark matter heavier than the reheating temperature .
we generalize the well known analysis of heavy dark matter production for general equation of state @xmath0 of the oscillating inflaton field .
however , at the end we consider effective equation of state @xmath1 emerging form our model .
where , @xmath2 is the index of the power law potential during late time oscillatory phase . considering present value of the dark matter abundance @xmath3 ,
we constrain the parameter space of annihilation cross - section ( @xmath4 ) and mass @xmath5 of a single component dark matter for different reheating temperature and equation of state @xmath0 . .
And you have already written the first three sentences of the full article: the inflationary paradigm@xcite proposed around @xmath6 was a giant leap towards going beyond the standard model of big - bang cosmology . since then there has been a plethora of inflationary models and it is still increasing @xcite .
however , with the high precision observational cosmology @xcite , any cosmological model building will have to take care of strong observational constraints . by
now inflation has become an integral part of the modern theoretical cosmology ..
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it is an exponential expansion at the very early stage of our universe .
so far this is the only mechanism which can successfully generate all the suitable initial boundary conditions for the standard big - bang cosmology .
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Suppose that you have an abstract for a scientific paper: we present new results on instabilities in rapidly and differentially rotating neutron stars .
we model the stars in full general relativity and describe the stellar matter adopting a cold realistic equation of state based on the unified sly prescription @xcite .
we provide evidence that rapidly and differentially rotating stars that are below the expected threshold for the dynamical bar - mode instability , @xmath0 , do nevertheless develop a shear instability on a dynamical timescale and for a wide range of values of @xmath1 .
this class of instability , which has so far been found only for small values of @xmath1 and with very small growth rates , is therefore more generic than previously found and potentially more effective in producing strong sources of gravitational waves .
overall , our findings support the phenomenological predictions made by watts , andersson and jones @xcite on the nature of the low-@xmath2 instability as the manifestation of a shear instability in a region where the latter is possible only for small values of the @xmath1 . furthermore ,
our results provide additional insight on shear instabilities and on the necessary conditions for their development . .
And you have already written the first three sentences of the full article: non - axisymmetric deformations of rapidly rotating bodies are rather generic phenomena in nature and can appear in a wide class of systems .
particularly interesting within an astrophysical context are those deformations taking place in fluids that are self - gravitating and the literature on this has a long history dating back to the work of @xcite on incompressible newtonian uniformly rotating bodies . since then , the study of these instabilities has continued over the years both in newtonian gravity and in full general relativity .
special attention has traditionally been paid to the study of @xmath3 instabilities , which are characterized by the exponential growth of @xmath3 deformations , where @xmath4 parametrizes the azimuthal dependence @xmath5 in a standard mode decomposition in spherical harmonics ..
Please generate the next two sentences of the article
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most of the interest in this type of deformation in compact stars stems from the fact that it has the shortest growth time and leads to the emission of a strong gravitational - wave signal .
the development of non - axisymmetric instabilities is commonly analyzed in terms of the quantity @xmath6 ( _ i.e. _ the ratio between the kinetic rotational energy @xmath7 and the gravitational potential energy @xmath8 ) , that provides a dimensionless measure of the amount of angular momentum that can be tapped to feed the development of the instabilities .
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10,587 |
Suppose that you have an abstract for a scientific paper: the simplest explanation for early time acceleration ( inflation ) and the late time acceleration indicated by recent data is that they have a common origin .
we investigate another generic cosmological implication of this possiblity , that the baryon asymmetry of the universe may be generated in such models .
we identify several novel features of baryogenesis in such a universe , in which a rolling scalar field is always part of the cosmological energy budget .
we also propose a concrete mechanism by which the baryon asymmetry of the universe may be generated in this context .
we analyze the generic properties of and constraints on these cosmologies , and then demonstrate explicitly how a complete cosmology may develop in some specific classes of models . .
And you have already written the first three sentences of the full article: rolling scalar fields are a mainstay of modern cosmology .
this is perhaps best - illustrated by the inflationary paradigm @xcite , in which most implementations involve a scalar field rolling towards the minimum of its potential in such a way that the potential energy of the field is the dominant component of the energy density of the universe .
there are , however , many other cosmological instances in which scalar fields are invoked . during the last few years a new consistent picture of the energy budget of the universe has emerged ..
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large scale structure studies show that matter ( both luminous and dark ) contributes a fraction of about 0.3 of the critical density , while the position of the first acoustic peak of the cosmic microwave background power spectrum indicates that the total energy density is consistent with criticality .
the discrepancy between these two measurements may be reconciled by invoking a negative pressure component which is termed _
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Suppose that you have an abstract for a scientific paper: we provide new results concerning label efficient , polynomial time , passive and active learning of linear separators . we prove that active learning provides an exponential improvement over pac ( passive ) learning of homogeneous linear separators under nearly log - concave distributions .
building on this , we provide a computationally efficient pac algorithm with optimal ( up to a constant factor ) sample complexity for such problems .
this resolves an open question of @xcite concerning the sample complexity of efficient pac algorithms under the uniform distribution in the unit ball .
moreover , it provides the first bound for a polynomial - time pac algorithm that is tight for an interesting infinite class of hypothesis functions under a general and natural class of data - distributions , providing significant progress towards a longstanding open question of @xcite .
we also provide new bounds for active and passive learning in the case that the data might not be linearly separable , both in the agnostic case and and under the tsybakov low - noise condition . to derive our results , we provide new structural results for ( nearly ) log - concave distributions , which might be of independent interest as well . active learning , pac learning , erm , nearly log - concave distributions , tsybakov low - noise condition , agnostic learning . .
And you have already written the first three sentences of the full article: learning linear separators is one of the central challenges in machine learning .
they are widely used and have been long studied both in the statistical and computational learning theory .
a seminal result of @xcite , using tools due to @xcite , showed that @xmath0-dimensional linear separators can be learned to accuracy @xmath1 with probability @xmath2 in the classic pac model in polynomial time with @xmath3 examples ..
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the best known lower bound for linear separators is @xmath4 , and this holds even in the case in which the distribution is uniform @xcite . whether the upper bound can be improved to match the lower bound via a polynomial - time algorithm is been long - standing open question , both for general distributions @xcite and for the case of the uniform distribution in the unit ball @xcite . in this work
we resolve this question in the case where the underlying distribution belongs to the class of log - concave and nearly log - concave distributions , a wide class of distributions that includes the gaussian distribution and uniform distribution over any convex set , and which has played an important role in several areas including sampling , optimization , integration , and learning @xcite .
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Suppose that you have an abstract for a scientific paper: conformal higher spin ( chs ) field theory , which is a solid part of recent advanced checks of ads / cft correspondence , finds applications in cosmology .
hidden sector of weakly interacting chs fields suggests a resolution of the hierarchy problem in the model of initial conditions for inflationary cosmology driven by a conformal field theory .
these initial conditions are set by thermal garland type cosmological instantons in the sub - planckian energy range for the model of chs fields with a large positive coefficient @xmath0 of the gauss - bonnet term in their total conformal anomaly and a large number of their polarizations @xmath1 .
the upper bound of this range @xmath2 is shown to be much lower than the gravitational cutoff @xmath3 which is defined by the requirement of smallness of the perturbatively nonrenormalizable graviton loop contributions . in this way we justify the approximation scheme in which the nonrenormalizable graviton sector is subject to effective field theory under this cutoff ,
whereas the renormalizable sector of multiple chs fields is treated beyond perturbation theory and dynamically generates the bound on the inflation scale of the cft cosmology @xmath4 .
this confirms recent predictions for the origin of the starobinsky @xmath5 and higgs inflation models from the chs cosmology , which occurs at the energy scale three or four orders of magnitude below the gravitational cutoff , @xmath6 .
we also consider cosmological models dominated by fermionic chs fields with a negative @xmath0 and anomaly free models of infinite towers of chs fields with @xmath7 and briefly discuss the status of unitarity in chs models .
_ theory department , lebedev physics institute , leninsky prospect 53 , moscow 119991 , russia _ + _ department of physics , tomsk state university , lenin ave .
36 , tomsk 634050 , russia _ + _ and _ + _ pacific institue for theoretical physics , department of physics and astronomy , university
_ + _ of british columbia ,....
And you have already written the first three sentences of the full article: rapidly developing trend in nonperturbative approach to quantum gravity and string theory , which is based on holographic ideas of ads / cft correspondence @xcite , involves vasiliev theory of interacting higher spin fields @xcite and naturally leads to the notion of conformal higher spin fields ( chs ) @xcite .
though these chs fields represent thus far only a playground for rather sophisticated verification of the ads / cft correspondence @xcite , quite interestingly they turn out to be important in recent cosmological applications associated with the problem of initial conditions in the early inflationary universe @xcite .
this is the model of the cft driven cosmology @xcite which incorporates two main ideas a new concept of the cosmological microcanonical density matrix as the initial state of the universe and the implementation of this concept in cosmology with a large number of quantum fields conformally coupled to gravity ..
Please generate the next two sentences of the article
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this model plays important role within quantum cosmology and within the cosmological constant and dark energy problems .
in particular , it resolves the issue of infrared catastrophe associated with the observer independent treatment of the no - boundary state @xcite an anti - intuitive conclusion that the origin of an infinitely big universe ( with an insufficient amount of inflation produced at the zero minimum of the inflaton potential rather than its maximum ) is infinitely more probable than that of a finite one .
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Suppose that you have an abstract for a scientific paper: we study the entanglement properties of two three - level rydberg atoms passing through a single - mode cavity .
the interaction of an atom with the cavity field allows the atom to make a transition from the upper most ( lower most ) to the lower most ( upper most ) level by emission ( absoprtion ) of two photons via the middle level .
we employ an effective hamiltonian that describes the system with a stark shifted two - photon atomic transition .
we compute the entanglement of formation of the joint two - atom state as a function of rabi angle @xmath0 .
it is shown that the stark shift can be used to enhance the magnitude of atomic entanglement over that obtained in the resonant condition for certain parameter values .
we find that though the two - atom entanglement generally diminishes with the increase of the two - photon detuning and the stark shift , it is possible to sustain the entanglement over a range of interaction times by making the detuning and the stark shift compensate each other .
similar characteristics are obtained for a thermal state cavity field too
. 0.5 cm .
And you have already written the first three sentences of the full article: the most interesting idea associated with composite quantum systems is quantum entanglement .
a pair of particles is said to be entangled in quantum mechanics if its state can not be expressed as a product of the states of its individual constituents .
einstein , podolsky and rosen@xcite were the first to point out certain nontrivial consequences of entanglement on the ontology of quantum theory ..
Please generate the next two sentences of the article
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the preparation and manipulation of these entangled states lead to a better understanding of basic quantum phenomena .
for example , complex entangled states , such as the greenberger , horne and zeilinger@xcite triplets of particles are used for tests of quantum nonlocality@xcite . beyond these fundamental aspects
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10,591 |
Suppose that you have an abstract for a scientific paper: experimental evidence for majorana bound states largely relies on measurements of the tunneling conductance .
while the conductance into a majorana state is in principle quantized to @xmath0 , observation of this quantization has been elusive , presumably due to temperature broadening in the normal - metal lead . here , we propose to use a superconducting lead instead , whose gap strongly suppresses thermal excitations . for a wide range of tunneling strengths and temperatures ,
a majorana state is then signaled by symmetric conductance peaks at @xmath1 of a universal height @xmath2 . for a superconducting scanning
tunneling microscope tip , majorana states appear as spatial conductance plateaus while the conductance varies with the local wavefunction for trivial andreev bound states .
we discuss effects of nonresonant ( bulk ) andreev reflections and quasiparticle poisoning .
_ introduction._motivated by possible applications in quantum information processing @xcite , topological superconductors hosting majorana bound states are currently under intense investigation @xcite . based on the superconducting proximity effect ,
various realistic platforms have been proposed to support majorana states including topological insulators @xcite , semiconductor nanowires @xcite , and atomic chains @xcite .
although these systems are available in the laboratory , the experimental observation of unique majorana signatures remains challenging .
a widely employed diagnostic tool is the tunneling conductance of normal metal
superconductor junctions , in which majoranas manifest themselves as characteristic zero - bias peaks @xcite .
experimental signatures consistent with theoretical predictions have been observed in quantum wires @xcite and atomic chains @xcite .
however , it is a major challenge in these experiments to uniquely distinguish majoranas from conventional fermionic subgap states .
spin - polarized subgap states such as shiba states bound to magnetic impurities @xcite or andreev....
And you have already written the first three sentences of the full article: in this section , we outline the derivation of the tunneling current in eq .
( 2 ) of the main text .
this standard calculation is included to make the presentation self contained and closely follows the derivation for @xmath107 green functions presented in ref ..
Please generate the next two sentences of the article
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we describe the tunneling contact by the hamiltonian @xmath108 , where the three terms refer to the lead ( tip ) , the sample , and the tunnel coupling . the superconducting tip with chemical potential @xmath109 and gap @xmath6 is described by the bcs hamiltonian @xmath110,\end{aligned}\ ] ] where @xmath111 and @xmath112 ( @xmath113 ) annihilates ( creates ) an electron in the tip with momentum @xmath114 and spin @xmath115 .
the sample hamiltonian generally takes the form @xmath116 where @xmath117 is the hamiltonian in first quantization and @xmath118 annihilates an electron with spin @xmath115 at position @xmath45 in the sample .
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10,592 |
Suppose that you have an abstract for a scientific paper: nicos , nightly control system , is a flexible tool for coordination of software development in large - scale projects .
it manages the multi - platform nightly builds based on the recent versions of software packages , tries to compensate for technical failures , tests the newly built software , identifies possible problems , and makes results immediately available to developers spread over different institutions and countries .
the nicos nightly build services ensure that new software submissions are consistent and provide expected results .
the nicos tool was developed to coordinate the efforts of more than 100 developers from 34 countries for the atlas project at cern and can be easily adapted for other large software projects . .
And you have already written the first three sentences of the full article: the software projects for high energy physics experiments are international with often several hundreds programmers from institutions world - wide involved .
the coordination of distributed software development is an important factor of success .
the automated nightly builds become a major component in collaborative software organization and management . in multi - person , multi - platform environment they provide a fast feedback to developers on new code submissions and facilitate collective work on different or same parts of software ..
Please generate the next two sentences of the article
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nicos @xcite was originally created for the atlas experiment @xcite and evolved in a versatile nightly builds system .
it operates on unix - like platforms and works with known release management tools , such as scram @xcite and cmt @xcite .
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10,593 |
Suppose that you have an abstract for a scientific paper: we present new observations and analysis of g2 the intriguing red emission - line object which is quickly approaching the galaxy s central black hole .
the observations were obtained with the laser guide star adaptive optics systems on the w. m. keck i and ii telescopes and include spectroscopy ( @xmath0 ) centered on the hydrogen br-@xmath1 line as well as @xmath2 ( 2.1 ) and @xmath3 ( 3.8 ) imaging .
analysis of these observations shows the br-@xmath1 line emission has a positional offset from the @xmath3 continuum .
this offset is likely due to background source confusion at @xmath3 .
we therefore present the first orbital solution derived from br-@xmath1 line astrometry , which when coupled with radial velocity measurements , results in a later time of closest approach ( @xmath4 ) , closer periastron ( @xmath5 , @xmath6 ) , and higher eccentricity ( @xmath7 ) compared to a solution using @xmath3 astrometry .
the new orbit casts doubt on previous associations of g2 and a low surface brightness `` tail . ''
it is shown that g2 has no @xmath2 counterpart down to @xmath8 .
g2 s @xmath3 continuum and the br-@xmath1 line - emission is unresolved in almost all epochs ; however it is marginally extended in our highest quality br-@xmath1 data set from 2006 and exhibits a clear velocity gradient at that time . while the observations altogether suggest that g2 has a gaseous component which is tidally interacting with the central black hole , there is likely a central star providing the self - gravity necessary to sustain the compact nature of this object . .
And you have already written the first three sentences of the full article: recently , @xcite reported the discovery of g2 , an extremely red object with spatially resolved br-@xmath1 emission .
the object was interpreted as a @xmath9 earth mass gas cloud based upon an inferred low dust temperature , observed elongation of the br-@xmath1 emission along the object s direction of motion , and a claimed tail along the same orbital trajectory as g2 .
this interpretation is particularly interesting because g2 is on a highly eccentric orbit with closest approach to our galaxy s central black hole within the next year , potentially allowing us to observe an unprecedented accretion event onto a supermassive black hole and offer insight into the region surrounding the black hole ( e.g. * ? ? ?.
Please generate the next two sentences of the article
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* ; * ? ? ?
* ; * ? ? ?
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10,594 |
Suppose that you have an abstract for a scientific paper: the standard treatment of gravitational lensing by a point mass lens @xmath0 is based on a weak - field deflection angle @xmath1 , where @xmath2 with @xmath3 the distance of closest approach to the mass of a lensed light ray .
it was shown that for a point mass lens , the total magnification and image centroid shift of a point source remain unchanged by relativistic corrections of second order in @xmath4 .
this paper considers these issues analytically taking into account the relativistic images , under three assumptions * a1**a3 * , for a schwarzschild black hole lens with background point and extended sources having arbitrary surface brightness profiles .
the assumptions are * a1 : * the source is close to the line of sight and lies in the asymptotically flat region outside the black hole lens ; * a2 : * the observer - lens and lens - source distances are significantly greater than the impact parameters of the lensed light rays ; and * a3 : * the distance of closest approach of any light ray that does not wind around the black hole on its travel from the source to the observer , lies in the weak - field regime outside the black hole .
we apply our results to the galactic black hole for lensing scenarios where * a1**a3 * hold .
we show that a single factor characterizes the full relativistic correction to the weak - field image centroid and magnification . as the lens - source distance increases , the relativistic correction factor strictly decreases .
in particular , we find that for point and extended sources about @xmath5 behind the black hole , which is a distance significantly outside the tidal disruption radius of a sun - like source , the relativistic correction factor is minuscule , of order @xmath6 .
therefore , for standard lensing configurations , any detectable relativistic corrections to microlensing by the galactic black hole will most likely have to come from sources significantly closer to the black hole .
[ firstpage ] black holes : strong field regime gravitational....
And you have already written the first three sentences of the full article: microlensing describes gravitational lensing of a source whose multiple images are not resolved .
two fundamental microlensing observables are the total magnification ( photometry ) and image centroid shift ( astrometry ) of images of a lensed source .
these observables have important astrophysical applications such as determining the mass and distance to the lens , angular radius of the source , etc ..
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( see , e.g. , @xcite , @xcite , @xcite , @xcite , @xcite , and references therein ) . a natural issue to explore
is how are the photometry and astrometry of a source being lensed by a point mass changed when the point mass is replaced by a black hole lens .
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Suppose that you have an abstract for a scientific paper: a catalogue of 231 galactic supernova remnants ( snrs ) is presented , and the selection effects applicable to the identification of remnants at radio wavelengths are discussed .
in addition to missing low surface brightness remnants , small angular size
i.e. young but distant remnants are also missing from the current catalogue of galactic snrs .
several statistical properties of galactic snrs are discussed , including the surface - brightness / diameter ( @xmath0 ) relation .
it is concluded that the wide range of intrinsic properties of galactic remnants with known distances , together with the observational selection effects , means that use of the @xmath0 relation to derive diameters and hence distances for individual snrs , or for statistical studies , is highly uncertain . the observed distribution of bright snrs , which are thought to be largely free from selection effects ,
is also used to derive a simple model for the distribution of snrs with galactocentric radius .
[ firstpage ] supernova remnants catalogues radio continuum : ism galaxy : structure ism : general .
And you have already written the first three sentences of the full article: our galaxy contains over two hundred known supernova remnants ( snrs ) , which are an important source of energy and heavy element release into the interstellar medium ( ism ) , and are also thought to be the sites of the acceleration of cosmic rays . over the last twenty years i have produced several versions of a catalogue of galactic snrs , the most recent revised in 2004 january ( see appendix [ s : appendix ] ) .
since the first version of the catalogue was published in green ( 1984 ) , the number of identified galactic snrs has increased considerably , from 145 to 231 , and here i review some of the statistical properties of galactic remnants based on the most recent version of the catalogue . in section [
s : catalogue ] the catalogue is described , while the selection effects applicable to the identification of galactic snrs are discussed in section [ s : selection ] ..
Please generate the next two sentences of the article
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some simple statistical properties of the remnants are presented in section [ s : simple ] , with more detailed discussions of distance - dependant statistical studies of galactic snrs ( including a brief discussion of some aspects of extragalactic remnants ) and the galactic distribution of snrs given in sections [ s : distance ] and [ s : distribution ] respectively .
the summary parameters of the 231 remnants from the 2004 january version of the catalogue of galactic snrs are presented in appendix [ s : appendix ] .
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10,596 |
Suppose that you have an abstract for a scientific paper: in an earlier work , the statistical physics associated with finite temperature decoding of code ensembles , along with the relation to their random coding error exponents , were explored in a framework that is analogous to derrida s random energy model ( rem ) of spin glasses , according to which the energy levels of the various spin configurations are independent random variables .
the generalized rem ( grem ) extends the rem in that it introduces correlations between energy levels in an hierarchical structure . in this paper
, we explore some analogies between the behavior of the grem and that of code ensembles which have parallel hierarchical structures .
in particular , in analogy to the fact that the grem may have different types of phase transition effects , depending on the parameters of the model , then the above mentioned hierarchical code ensembles behave substantially differently in the various domains of the design parameters of these codes .
we make an attempt to explore the insights that can be imported from the statistical mechanics of the grem and be harnessed to serve for code design considerations and guidelines .
+ + * index terms : * spin glasses , grem , phase transitions , random coding , error exponents .
department of electrical engineering + technion - israel institute of technology + haifa 32000 , israel + .
And you have already written the first three sentences of the full article: in the last few decades it has become apparent that many problems in information theory have analogies to certain problems in the area of statistical physics of disordered systems .
such analogies are useful because physical insights , as well as statistical mechanical tools and analysis techniques can be harnessed in order to advance the knowledge and the understanding with regard to the information
theoretic problem under discussion ..
Please generate the next two sentences of the article
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one important example of such an analogy is between the statistical physics of disordered magnetic materials , a.k.a .
spin glasses , and the behavior of certain ensembles of random codes for source coding ( see , e.g. , @xcite , @xcite , @xcite , @xcite ) and for channel coding ( see , e.g. , @xcite and references therein , @xcite , @xcite , @xcite , @xcite , @xcite , @xcite @xcite , @xcite , @xcite , @xcite , @xcite , @xcite , @xcite , @xcite , @xcite ) . among the various models of interaction disorder in spin glasses , one of the most fascinating models is the _ random energy model _ ( rem ) , invented by derrida in the early eighties @xcite , @xcite , @xcite ( see also , e.g. , @xcite , @xcite , @xcite , for later developments ) .
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10,597 |
Suppose that you have an abstract for a scientific paper: a finite difference upwind discretization scheme in two dimensions is presented in detail for the transient simulation of the highly coupled non - linear partial differential equations of the full hydrodynamic model , providing thereby a practical engineering tool for improved charge carrier transport simulations at high electric fields and frequencies .
the discretization scheme preserves the conservation and transportive properties of the equations .
the hydrodynamic model is able to describe inertia effects which play an increasing role in different fields of micro- and optoelectronics , where simplified charge transport models like the drift - diffusion model and the energy balance model are no longer applicable .
results of extensive numerical simulations are shown for a two - dimensional mesfet device .
a comparison of the hydrodynamic model to the commonly used energy balance model is given and the accuracy of the results is discussed . .
And you have already written the first three sentences of the full article: there is a growing interest in extended charge transport models for semiconductor devices .
our paper emerges from the the fact that today s submicron semiconductor devices like e.g. mesfets and hemts are operated under strong electric fields and at high frequencies .
information transmission using an electromagnetic wave at very high frequencies will have a direct impact on how we design active and passive components in different fields of micro- and optoelectronics ..
Please generate the next two sentences of the article
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in such cases , quasi - static semiconductor device models like the energy balance model ( ebm ) are no longer adequate . especially in gaas and related materials used for high - speed device design ,
inertia effects play an important role since the momentum and energy relaxation times of the electron gas are close to the picosecond range
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10,598 |
Suppose that you have an abstract for a scientific paper: we show that for a typical coordinate projection of a subgaussian class of functions , the infimum over signs @xmath0 is asymptotically smaller than the expectation over signs as a function of the dimension @xmath1 , if the canonical gaussian process indexed by @xmath2 is continuous . to that end
, we establish a bound on the discrepancy of an arbitrary subset of @xmath3 using properties of the canonical gaussian process the set indexes , and then obtain quantitative structural information on a typical coordinate projection of a subgaussian class . . .
And you have already written the first three sentences of the full article: the geometric structure of a random coordinate projection of a class of functions plays an important role in empirical processes theory , where it is used to determine whether the uniform law of large numbers or the uniform central limit theorem is satisfied by the given class .
indeed , if @xmath2 is a class of functions on a probability space @xmath4 , and if @xmath5 is an independent sample distributed according to @xmath6 , then the `` complexity '' of the random set @xmath7 is the key parameter in addressing both these questions . in this context ,
if @xmath8 are independent , symmetric , @xmath9-valued random variables , then the complexity is governed by the expectation of the supremum of the bernoulli process indexed by @xmath10 , defined by @xmath11 and in particular , on the way this expectation grows as a function of @xmath1 for a typical sample of cardinality @xmath1 ( see , e.g. , @xcite and references therein ) ..
Please generate the next two sentences of the article
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the structure of such coordinate projections is central to questions in asymptotic geometric analysis as well .
for example , let @xmath12 be a convex , symmetric set ( i.e. , if @xmath13 then @xmath14 ) and put @xmath15 to be the class of linear functionals indexed by @xmath16 . if @xmath17 is a measure on @xmath18 , then @xmath10 is the set @xmath19 , where @xmath20 is the random operator @xmath21 .
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10,599 |
Suppose that you have an abstract for a scientific paper: we compute topological correlators in landau - ginzburg models on a riemann surface with arbitrary number of handles and boundaries .
the boundaries may correspond to arbitrary topological d - branes of type b. we also allow arbitrary operator insertions on the boundary and in the bulk .
the answer is given by an explicit formula which can be regarded as an open - string generalization of c. vafa s formula for closed - string topological correlators .
we discuss how to extend our results to the case of landau - ginzburg orbifolds .
hep - th/0305136 .
And you have already written the first three sentences of the full article: topological landau - ginzburg models are an important class of 2d topological field theories ( 2d tfts ) . when coupled to topological gravity , they give soluble examples of noncritical string backgrounds .
they are also closely related to topological sigma - models describing superstring propagation in calabi - yau manifolds ( the so - called cy / lg correspondence ) . c. vafa showed how to compute topological correlators in landau - ginzburg ( lg ) models on riemann surfaces of arbitrary genus @xcite .
remarkably , the answer is given by a simple closed formula ..
Please generate the next two sentences of the article
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the goal of this paper is to generalize the results of ref .
@xcite to riemann surfaces with boundaries .
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