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4,500 | Suppose that you have an abstract for a scientific paper: density oscillations of confined one - dimensional fermi gases of contact repulsive interactions in a continuous space are discussed within bethe - ansatz based spin - density functional theory .
the results are compared against the exact analytical and the exact diagonalization method . for unpolarized system ,
the number of the peaks in the density profiles is doubled signaling the crossover of the @xmath0-friedel to @xmath1-wigner oscillations ( with @xmath2 the fermi wave vector ) . for both unpolarized and polarized systems , a threshold of the short - range interaction strength
can be found where @xmath3-peak wigner oscillations of @xmath1 wave vector appear in the density profile ( @xmath3 is the total particle number ) . .
And you have already written the first three sentences of the full article: in higher dimensions a true crystal , named wigner crystal , where the density is perfectly ordered , is possible when the repulsion between particles dominates over the kinetic energy in the case of small density . in one dimension , quantum fluctuations prevent any type of true spin - symmetry breaking and long - range order in the ground state , and thus the crystal does not have perfect order @xcite .
however , in one dimension , the equilibrium positions of the electrons are assumed to be equally spaced and a solid like state can be produced when the correlation length exceeds the sample length @xcite .
the liquid - to - quasi - wigner crystal crossover when the density decreasing can be characterized by the onset of the @xmath1-peak in the static structure factor following from the luttinger liquid predictions @xcite , with @xmath2 the fermi wave vector ( related to the fermion density @xmath4 by @xmath5 ) , or by the @xmath6 high - contrast peaks in the pair correlation function @xcite , with @xmath3 the particle number in the system . in the system where the constituent particles are not electrons but dilute atoms.
Please generate the next two sentences of the article | , the fundamental interaction is no longer of long - range coulomb type but of short - range contact one , which is the case in the field of ultracold atomic systems . in this system
, the ground - state density profile displays at strong coupling well - pronounced wigner oscillations with a ` @xmath7 periodicity ' |
4,501 | Suppose that you have an abstract for a scientific paper: using a characterization of mutual complete dependence copulas , we show that , with respect to the sobolev norm , the mcd copulas can be approximated arbitrarily closed by shuffles of min .
this result is then used to obtain a characterization of generalized shuffles of copulas introduced by durante , sarkoci and sempi in terms of mcd copulas and the @xmath0-product discovered by darsow , nguyen and olsen .
since shuffles of a copula is the copula of the corresponding shuffles of the two continuous random variables , we define a new norm which is invariant under shuffling .
this norm gives rise to a new measure of dependence which shares many properties with the maximal correlation coefficient , the only measure of dependence that satisfies all of rnyi s postulates .
copulas , shuffles of min , measure - preserving , sobolev norm @xmath0-product , shuffles of copulas , measure of dependence 28a20 , 28a35 , 46b20 , 60a10 , 60b10 .
And you have already written the first three sentences of the full article: since the copula of two continuous random variables is scale - invariant , copulas are regarded as the functions that capture dependence structure between random variables . for many purposes , independence and monotone dependence
have so far been considered two opposite extremes of dependence structure . however , monotone dependence is just a special kind of dependence between two random variables .
more general complete dependence happens when functional relationship between continuous random variables are piecewise monotonic , which corresponds to their copula being a shuffle of min ..
Please generate the next two sentences of the article | see @xcite .
mikusinski et al . |
4,502 | Suppose that you have an abstract for a scientific paper: we study series of the stationary solutions with asymptotic flatness properties in the einstein - maxwell - free scalar system because they are locally equivalent with the exterior solutions in some class of the scalar - tensor theories of gravity .
first , we classify spherical exterior solutions into two types of the solutions , an apparently black hole type solution and an apparently worm hole type solution .
the solutions contain three parameters , and we clarify their physical significance .
second , we reduce the field equations for the axisymmetric exterior solutions . we find that the reduced equations are partially the same as the ernst equations . as simple examples ,
we derive new series of the static , axisymmetric exterior solutions , which correspond to voorhees s solutions .
we then show a non - trivial relation between the spherical exterior solutions and our new solutions .
finally , since null geodesics have conformally invariant properties , we study the local geometry of the exterior solutions by using the optical scalar equations and find some anomalous behaviors of the null geodesics . .
And you have already written the first three sentences of the full article: recently , as natural alternatives to general relativity , the scalar - tensor theories have been studied by many theoretical physicists . in these theories ,
the gravity is mediated not only by a tensor field but also by a scalar field .
also , such theories have been of interest as effective theories of the string theory at low energy scales @xcite ..
Please generate the next two sentences of the article | several theoretical predictions in the scalar - tensor theories have been obtained ( see e.g. ref.@xcite@xmath0@xcite ) .
it has been found that a wide class of the scalar - tensor theories can pass all the experimental tests in weak gravitational fields . |
4,503 | Suppose that you have an abstract for a scientific paper: a new version release ( 2.0 ) of the molecular simulation tool _ ms_2 [ s. deublein et al . , comput .
phys .
commun . 182
( 2011 ) 2350 ] is presented .
version 2.0 of _ ms_2 features a hybrid parallelization based on mpi and openmp for molecular dynamics simulation to achieve higher scalability .
furthermore , the formalism by lustig [ r. lustig , mol .
phys . 110
( 2012 ) 3041 ] is implemented , allowing for a systematic sampling of massieu potential derivatives in a single simulation run .
moreover , the green - kubo formalism is extended for the sampling of the electric conductivity and the residence time . to remove the restriction of the preceding version to electro - neutral molecules
, ewald summation is implemented to consider ionic long range interactions . finally , the sampling of the radial distribution function is added . .
And you have already written the first three sentences of the full article: molecular modeling and simulation is a technology central to many areas of research in academia and industry . with the advance of computing power ,
the scope of application scenarios for molecular simulation is widening , both in terms of complexity of a given simulation and in terms of high throughput .
nowadays , e.g. the predictive simulation of entire phase equilibrium diagrams has become feasible ..
Please generate the next two sentences of the article | however , in order to rely on simulation results , the methodology needs to be sound and the implementation must be thoroughly verified . in its first release @xcite
, we have introduced the molecular simulation tool @xmath02 . |
4,504 | Suppose that you have an abstract for a scientific paper: the notion of the _ genus _ of a quadratic form is generalized to vertex operator algebras .
we define it as the modular braided tensor category associated to a suitable vertex operator algebra together with the central charge .
statements similar as known for quadratic forms are formulated .
we further explain how extension problems for vertex operator algebras can be described in terms of the associated modular braided tensor category . .
And you have already written the first three sentences of the full article: this note is a write - up of talks given at the workshop `` vertex operator algebras in mathematics and physics '' at the fields institute in toronto in october 2000 and at some other occasions before .
its purpose is to explain how results in low dimensional quantum field theory obtained from different perspectives and with different motivations can be put into a uniform picture by generalizing the notions of discriminant forms and genera from integral quadratic forms to vertex operator algebras , indicating a rich underlying arithmetical theory .
the relation between two - dimensional conformal field theory and three - dimensional topological quantum field theory has been quite known from the beginning ..
Please generate the next two sentences of the article | for example , witten relates in his well - known paper @xcite the wess - zumino - witten models with chern - simons theories and the jones polynomial of knots .
the basic idea is to use the monodromy properties of correlation functions on surfaces to obtain invariants for knots and three - dimensional manifolds . |
4,505 | Suppose that you have an abstract for a scientific paper: * a.a.b . , r.l . , and y.x . contributed equally .
+ + the soft character of organic materials leads to strong coupling between molecular nuclear and electronic dynamics .
this coupling opens the way to control charge transport in organic electronic devices by exciting molecular vibrational motions . however , despite encouraging theoretical predictions , experimental realization of such control has remained elusive .
here we demonstrate experimentally that photoconductivity in a model organic optoelectronic device can be controlled by the selective excitation of molecular vibrations . using an ultrafast infrared laser source to create a coherent superposition of vibrational motions in a pentacene / c60 photoresistor
, we observe that excitation of certain modes in the @xmath0{cm^{-1}}$ ] region leads to photocurrent enhancement .
excited vibrations affect predominantly trapped carriers .
the effect depends on the nature of the vibration and its mode - specific character can be well described by the vibrational modulation of intermolecular electronic couplings .
vibrational control thus presents a new tool for studying electron - phonon coupling and charge dynamics in ( bio)molecular materials .
+ * submitted * : nov .
11 , 2014 + * revised * : feb . 3 , 2015 the soft character of organic materials strongly influences their electronic functionality .
@xcite in these systems charge hopping and electronic delocalization are determined by the overlap of the molecular orbitals and , therefore , is highly sensitive to minor changes in molecular geometry .
hence , the electronic properties of organic materials are largely determined by the interplay between the electronic and nuclear dynamics of the molecules , referred to as vibronic coupling phenomena .
a growing number of interdisciplinary studies show that vibronic effects lie at the heart of a diverse class of effects in physics , chemistry and biology - from non - linear behavior of molecular junctions @xcite to photophysics of....
And you have already written the first three sentences of the full article: we thank richard friend , ayelet vilan and dassia egorova , as well as the reviewers , for useful discussions , and johannes zimmermann and tobias glaser for the angle - dependent ir spectra .
this work was supported by the netherlands organization for scientific research onderzoek ( nwo ) through the `` stichting voor fundamenteel onderzoek der materie '' ( fom ) research program .
also acknowledges a veni grant from the nwo ..
Please generate the next two sentences of the article | is currently a royal society university research fellow .
r.l . acknowledges a marie curie ie fellowship from the eu , held at the weizmann institute . |
4,506 | Suppose that you have an abstract for a scientific paper: short - distance qcd is employed to calculate the @xmath0 survival probability in an equilibrating parton gas , whose evolution is governed by a set of master rate equations .
partons in the early stage of high - energy nuclear collisions may initially not be in equilibrium , but their average transverse momentum is sufficiently high to break up a @xmath1 bound state .
such a break - up during the evolution of the parton gas is shown to cause a substantial @xmath0 suppression at both rhic and lhc energies , using realistic estimates of the initial parton densities .
the transverse momentum dependence of the suppression is also shown to be sensitive to the initial conditions and the evolution history of the parton plasma . 6.0 in 9.0 in .
And you have already written the first three sentences of the full article: it is generally believed , and confirmed by lattice qcd calculations @xcite , that hadronic matter under extreme conditions will form a plasma in which quarks and gluons are no longer confined to individual hadrons and are in both thermal and chemical equilibrium . to search for such a quark - gluon plasma , it is proposed to study collisions of heavy nuclei at extremely high energies .
recent work using models based on perturbative qcd indeed shows that at high energy a dense partonic system can be produced @xcite . though it is not all clear if such partonic systems will reach thermal and chemical equilibrium before hadronization @xcite , the partons , mainly gluons , are certainly in a deconfined state at such high densities @xcite .
many signals could arise from this deconfined state , such as charm quark enhancement @xcite or enhanced photon and dilepton production @xcite ..
Please generate the next two sentences of the article | charm quarks , for example , can not be easily produced during the mixed and hadronic phases of the dense matter , due to their large masses compared to the temperature .
they can be readily produced only during the early stage of the evolution , when partonic degrees of freedom are relevant . in this paper |
4,507 | Suppose that you have an abstract for a scientific paper: we develop a new general formulation to explore light - driven electron transport through a single - molecule device with multiple pathways .
three individual systems are proposed including ( i ) a two - terminal molecular junction based on phenyl - acetylene macrocycle ( pam ) , ( ii ) pam with three terminals , and ( iii ) a parallel molecular circuit .
the computations show that pam - based optoelectronic switches have robust large on - off ratios and weak - field operating conditions , which are not sensitive to asymmetric molecule - lead couplings .
in addition , field - amplitude power laws for one- and two - photon assisted tunneling are evident in the computational results , and the laws can be proven by using perturbation analysis . for pam - based optoelectronic routers ,
we show that it is possible to manipulate the direction of electric current through the pam molecule by using a weak linearly polarized laser field . for parallel circuits made of molecular quantum dots ,
the condition of coherent destruction of tunneling is derived by using the rotating wave approximation and the high - frequency approximation . .
And you have already written the first three sentences of the full article: molecular electronics is an active field with many potential applications and novel innovations in nanoelectronic devices @xcite .
an ultimate goal in molecular electronics is to construct molecule - based integrated circuits . to achieve this goal , understanding electron transport through a single - molecule device ( junction ) is a required first step . during the past two decades
, great experimental progress has been made on single - molecule junctions due to advancements in microfabrication and self - assembly techniques @xcite ..
Please generate the next two sentences of the article | in addition , improvements in theoretical modeling have enabled successful explanations and predictions of experimental observations , e.g. , kondo effect@xcite , thermoelectricity @xcite , orbital gating @xcite , destructive quantum interference @xcite , and conductance dependence upon molecular conformation @xcite .
the landauer formula combined with the non - equilibrium green s function method @xcite has become a common approach to analyze electron transport through a single - molecule junction in the absence of applied fields . for a practical device |
4,508 | Suppose that you have an abstract for a scientific paper: we study the mass of the ground state of @xmath0 systems using different regularization schemes of the relativistic integral equation obtained with a flavor independent contact interaction in a qcd - inspired light - front model .
we calculate the masses of the spin 1/2 low - lying states of the @xmath1 , @xmath2 and @xmath3 for different values of the regularization cut - off parameter with a fixed nucleon mass .
our results are in remarkable agreement with the experimental data . .
And you have already written the first three sentences of the full article: the qcd - inspired light - front constituent quark model @xcite , with two components in the interaction , a contact term and a coulomb - like potential , was used previously to investigate the properties of mesons @xcite with reasonable success .
it was also applied to investigate the binding energy of the ground state of spin 1/2 @xmath0 baryons @xcite , where the coulomb - like interaction was left out . in that work
, a special regularization scheme was used in which the masses of the virtual two - body subsystems were constrained to be real , as a result the quark binding in the spin 1/2 low - lying states of the @xmath1 , @xmath4 and @xmath3 was qualitatively reproduced ..
Please generate the next two sentences of the article | recently , the integral equation for a three - boson system interacting with pairwise contact interaction in the light - front @xcite was regularized with a sharp cut - off @xcite and applied in the study of the nucleon . in the infinite cut - off limit
it was previously shown that the three - boson system is stable for values of the two - boson bound state mass above a critical value @xcite . |
4,509 | Suppose that you have an abstract for a scientific paper: we obtained the spectrum of probability of the bremsstrahlung emission accompanying the @xmath0-decay of @xmath1 ( e@xmath2=4.8 mev ) by measuring the @xmath0-@xmath3 coincidences and using the model presented in our previous study on the @xmath4decay of @xmath5 ( e@xmath2=7.7 mev ) .
we compare the experimental data with the quantum mechanical calculation and find a good agreement between theory and experiment .
we discuss the differences between the photon spectra connected with the @xmath0-decay of the @xmath1 and @xmath5 nuclei .
for the two mentioned nuclei we analyze the bremsstrahlung emission contributions from the tunneling and external regions of the nucleus barrier into the total spectrum , and we find the destructive interference between these contributions .
we also find that the emission of photons during tunneling of the @xmath0-particle gives an important contribution to the bremsstrahlung spectrum in the whole e@xmath6 energy range of the studied @xmath7ra nucleus . .
And you have already written the first three sentences of the full article: in recent years many experimental and theoretical efforts@xmath8 have been made to investigate on the nature of the bremsstrahlung emission in the @xmath0-decay of heavy nuclei , because the behavior of the energy spectrum of photons is strongly related to the dynamics of the @xmath0-decay and alpha nucleus particle potential . in some case
the energy spectrum of bremsstrahlung shows some slight oscillations@xcite , in other case authors observed a minimum@xcite , in some experiment authors@xcite have not observed evidence of any structure .
therefore the main problem to investigate the tunneling of the @xmath0-particle through the coulomb barrier of nucleus is to enlarge the area of the study on other nuclei and to compare the characteristics of the @xmath3-spectra . in this paper.
Please generate the next two sentences of the article | we present the results of the last experiment on the study of the bremsstrahlung emission in @xmath0-decay of @xmath1 .
we also analyze and discuss the comparison between the experimental and theoretical results of the photon emission related to the @xmath1 and @xmath5 nuclei . in sec . |
4,510 | Suppose that you have an abstract for a scientific paper: the supernova remnant kes 73 and/or the magnetar 1e 1841 - 045 at its center can deposit a large amount of energy to the surroundings and is potentially responsible for particle acceleration . using the data taken with the _ fermi _ large area telescope ( lat )
, we confirmed the presence of an extended source whose centroid position is highly consistent with this magnetar / supernova - remnant pair .
its emission is intense from 100 mev to @xmath0100 gev .
its lat spectrum can be decoupled into two components which are respectively governed by two different mechanisms . according to the young age of this system ,
the magnetar is seemingly a necessary and sufficient source for the downward - curved spectrum below 10 gev , as the observed @xmath110 gev flux is too high for the supernova remnant to account for . on the other hand ,
the supernova remnant is reasonably responsible for the hard spectrum above 10 gev .
further studies of this region in the tev regime is required , so that we can perform physically meaningful comparisons of the @xmath010 gev spectrum and the tev spectrum . .
And you have already written the first three sentences of the full article: magnetars are neutron stars with typically longer periods of spinning ( @xmath22@xmath312 s ) and stronger surface magnetic fields ( @xmath0@xmath4 g ) @xcite , compared to normal neutron stars .
their manifestations include soft gamma - ray repeaters ( sgrs ) and anomalous x - ray pulsars ( axps ) , which are mostly located at low galactic latitudes @xcite .
magnetars emit mainly by releasing magnetic energy rather than rotational energy @xcite . due to unusually high surface magnetic fields ,.
Please generate the next two sentences of the article | frequent starquakes occur on magnetars @xcite , leading to recurrent x - ray outbursts of magnetars ( cf .
* and references therein gcn circulars : http://gcn.gsfc.nasa.gov/gcn3_archive.html ] ) . |
4,511 | Suppose that you have an abstract for a scientific paper: inexact newton regularization methods have been proposed by hanke and rieder for solving nonlinear ill - posed inverse problems .
every such a method consists of two components : an outer newton iteration and an inner scheme providing increments by regularizing local linearized equations . the method is terminated by a discrepancy principle . in this paper we consider the inexact newton regularization methods with the inner scheme defined by landweber iteration , the implicit iteration , the asymptotic regularization and tikhonov regularization . under certain conditions
we obtain the order optimal convergence rate result which improves the suboptimal one of rieder .
we in fact obtain a more general order optimality result by considering these inexact newton methods in hilbert scales .
example.eps gsave newpath 20 20 moveto 20 220 lineto 220 220 lineto 220 20 lineto closepath 2 setlinewidth gsave .4 setgray fill grestore stroke grestore [ section ] # 1#1_2 # 1#1 @=12 .
And you have already written the first three sentences of the full article: inverse problems arise whenever one searches for unknown causes based on observation of their effects . driven by the requirements from huge amount of practical applications ,
the field of inverse problems has undergone a tremendous growth .
such problems are usually ill - posed in the sense that their solutions do not depend continuously on the data . in practical applications ,.
Please generate the next two sentences of the article | one never has exact data , instead only noisy data are available due to errors in the measurements . even if the deviation is very small , algorithms developed for well - posed problems may fail , since noise could be amplified by an arbitrarily large factor . therefore , the development of stable methods for solving inverse problems is a central topic . in this paper
we consider the stable resolution of nonlinear inverse problems which mathematically can be formulated as the nonlinear equations @xmath0 where @xmath1 is a nonlinear frchet differentiable operator between two hilbert spaces @xmath2 and @xmath3 whose norms and inner products are denoted as @xmath4 and @xmath5 respectively . |
4,512 | Suppose that you have an abstract for a scientific paper: in the perspective of comparisons between proton - proton and heavy - ion physics , understanding the production mechanisms ( soft and hard ) in that lead to strange particles is of importance .
measurements of charged multi - strange ( anti-)baryons ( and ) are presented for collisions at @xmath0 = 7 .
this report is based on results obtained by alice ( a large ion collider experiment ) from the 2010 data - taking .
+ taking advantage of the characteristic cascade - decay topology , the identification of , , and can be performed , over a wide range of momenta ( e.g. from 0.6 to 8.5 for , with the present statistics analysed ) .
the production at central rapidity ( @xmath1 ) as a function of transverse momentum , @xmath2 , is presented .
these results are compared to pythia perugia 2011 predictions . .
And you have already written the first three sentences of the full article: in heavy - ion ( ) as well as in proton - proton ( ) collisions , the measurements related to strange hadrons constitute unique tools to study the physics of the strong interaction . in this respect ,
given their strangeness content , the charged multi - strange baryons
( @xmath3 ) , ( @xmath4 ) , ( @xmath5 ) , ( @xmath6 ) are of certain importance . the interest in strangeness and specifically in and can be explained mainly by two reasons : * the initial system formed by the projectiles is free from strange valence quarks , thus the strange quarks that compose the strange hadrons of the final state have to be produced during the process of the collisions ; * due to the identification via weak - decay topology reconstruction , the multi - strange baryons can be studied over a large momentum range , typically from @xmath7 @xmath8 up to @xmath9 ..
Please generate the next two sentences of the article | the resulting @xmath7 spectra then cover the region dominated by the soft processes and reach the energy scale where hard scattering mechanisms may prevail .
a significant part of the investigation in physics depends on our understanding of the production mechanisms ( soft and hard ) in the system , meaning as they occur in the benchmark system . |
4,513 | Suppose that you have an abstract for a scientific paper: the galactic center is a hotbed of star formation activity , containing the most massive star formation site and three of the most massive young star clusters in the galaxy .
given such a rich environment , it contains more stars with initial masses above 100 than anywhere else in the galaxy .
this review concerns the young stellar population in the galactic center , as it relates to massive star formation in the region .
the sample includes stars in the three massive stellar clusters , the population of younger stars in the present sites of star formation , the stars surrounding the central black hole , and the bulk of the stars in the field population .
the fossil record in the galactic center suggests that the recently formed massive stars there are present - day examples of similar populations that must have been formed through star formation episodes stretching back to the time period when the galaxy was forming . .
And you have already written the first three sentences of the full article: the galactic center ( gc ) is an exceptional region for testing massive star formation and evolution models .
it contains 10% of the present star formation activity in the galaxy , yet fills only a tiny fraction of a percent of the volume in the galactic disk500 pc and thickness of @xmath060 pc that is centered on the galactic nucleus and is coincident with a region of increased dust and gas density , often referred to as the `` central molecular zone '' @xcite . ] .
the initial conditions for star formation in the gc are unique in the galaxy ..
Please generate the next two sentences of the article | the molecular clouds in the region are extraordinarly dense , under high thermal pressure , and are subject to a strong gravitational tidal field .
@xcite argue that these conditions may favor the preferential formation of high mass stars . |
4,514 | Suppose that you have an abstract for a scientific paper: we study quantum walks of many non - interacting particles on a beam splitter array , as a paradigmatic testing ground for the competition of single- and many - particle interference in a multi - mode system .
we derive a general expression for multi - mode particle - number correlation functions , valid for bosons and fermions , and infer pronounced signatures of many - particle interferences in the counting statistics . .
And you have already written the first three sentences of the full article: quantum walks ( qws ) provide the natural - yet unitary - extension of the classical random walk ( rw ) to the quantum regime @xcite , where the superposition principle allows a wave function to explore different paths simultaneously . the resulting interference in the transition amplitudes is cause to effects like the linear increase in time of the mean travelled distance of the quantum walker @xcite .
this ballistic behavior contrasts with the diffusive behavior of a classical particle performing a rw , whose mean travelled distance increases with the square root of time .
single - particle qws , as realized in various experiments @xcite , can also be mimicked with classical wave mechanics @xcite ..
Please generate the next two sentences of the article | in contrast , qws with two particles @xcite show purely quantum features due to many - particle interference or entanglement that no classical system can provide . for larger particle numbers ,
it is unknown how the emerging hierarchy of many - particle interference effects in terms of the number of contributing particles affects physical observables . |
4,515 | Suppose that you have an abstract for a scientific paper: new defects ( @xmath0-vortices and nambu monopoles ) are found to become thermodynamically relevant for the broken phase near to the ( weakly first order ) electroweak phase transition , and below the crossover for higher higgs mass . the symmetric phase is characterized by vortex condensation ( percolation ) .
the percolation transition persists in the crossover region .
the quasiclassical nature of the vortices is supported by correlations with higgs field and gauge field energy .
sphalerons are shown to be related to monopolium bound states . .
And you have already written the first three sentences of the full article: is the electroweak phase transition accompanied by the condensation of some defects ? what is happening with the defects at the crossover region
? is there a range of parameters supporting a dilute gas of such defects in the broken phase and how are they related to the well - known sphaleron configurations ?
these questions have been explored during the last year within the @xmath1 higgs model ..
Please generate the next two sentences of the article | the @xmath0-vortex string @xcite corresponds to the abrikosov
olesen @xcite vortex solution related to the abelian subgroup of @xmath1 embedded into the electroweak theory @xcite . |
4,516 | Suppose that you have an abstract for a scientific paper: we give criteria for which a principal curvature becomes a bounded @xmath0-function at non - degenerate singular points of wave fronts by using geometric invariants . as applications , we study singularities of parallel surfaces and extended distance squared functions of wave fronts .
moreover , we relate these singularities to some geometric invariants of fronts . .
And you have already written the first three sentences of the full article: in this paper , we study behavior of principal curvatures of wave fronts in the euclidean @xmath1-space @xmath2 with non - degenerate singular points which contain cuspidal edges and swallowtails , and their applications .
principal curvatures for regular surfaces play important roles to study the ( extrinsic ) differential geometry of surfaces and related topics .
for instance , types of singularities of parallel surfaces and focal surfaces of regular surfaces are closely related to critical points of principal curvatures , such points are called ridge points . in fact , porteous @xcite showed relations between cuspidal edges on a focal surface and ridge points on an initial surface by using singularity theory techniques ( cf ..
Please generate the next two sentences of the article | thus we expect that principal curvatures may play an important role to study wave fronts from the differential geometric viewpoint .
in @xcite , murata and umehara showed that at least one principal curvature is unbounded near a singular point . |
4,517 | Suppose that you have an abstract for a scientific paper: we extend previous measurements of cosmic infrared background ( cib ) fluctuations to @xmath0 using new data from the spitzer extended deep survey .
two fields , with depths of @xmath1 hr / pixel over 3 epochs , are analyzed at 3.6 and 4.5 .
maps of the fields were assembled using a self - calibration method uniquely suitable for probing faint diffuse backgrounds .
resolved sources were removed from the maps to a magnitude limit of mag@xmath2 , as indicated by the level of the remaining shot noise .
the maps were then fourier - transformed and their power spectra were evaluated .
instrumental noise was estimated from the time - differenced data , and subtracting this isolates the spatial fluctuations of the actual sky .
the power spectra of the source - subtracted fields remain identical ( within the observational uncertainties ) for the three epochs indicating that zodiacal light contributes negligibly to the fluctuations .
comparing to 8 power spectra shows that galactic cirrus can not account for the fluctuations .
the signal appears isotropically distributed on the sky as required for an extragalactic origin .
the cib fluctuations continue to diverge to @xmath3 times those of known galaxy populations on angular scales out to @xmath0 .
the low shot noise levels remaining in the diffuse maps indicate that the large scale fluctuations arise from the spatial clustering of faint sources well below the confusion noise .
the spatial spectrum of these fluctuations is in reasonable agreement with an origin in populations clustered according to the standard cosmological model ( @xmath4cdm ) at epochs coinciding with the first stars era . #
1= # 1 2sr 2m4sr .
And you have already written the first three sentences of the full article: the cosmic infrared background ( cib ) is the collective radiation emitted throughout cosmic history , including from sources inaccessible to current telescopic studies ( see review by kashlinsky , 2005 ) .
the latter category includes the very first luminous objects , currently a subject of intense investigations and great importance for astronomy and cosmology .
cib fluctuations can be more readily discerned than the actual mean level of the background allowing to overcome the significant galactic and solar system foregrounds at these wavelengths ( kashlinsky et al ..
Please generate the next two sentences of the article | 1996a , b , kashlinsky & odenwald 2000 ) .
it is generally believed now as a result of detailed numerical simulations of the formation of first structures in the standard cosmological model that the first objects to form in the universe , the so - called population iii stars , were very massive stars that occupied a brief era at epochs inaccessible to direct telescopic observations ( see review by bromm & et al . |
4,518 | Suppose that you have an abstract for a scientific paper: in this article we propose multiplication based random walk metropolis hastings ( mh ) algorithm on the real line .
we call it the random dive mh ( rdmh ) algorithm .
this algorithm , even if simple to apply , was not studied earlier in markov chain monte carlo literature .
one should not confuse rdmh with rwmh .
it is shown that they are different , conceptually , mathematically and operationally . the kernel associated with therdmh algorithm
is shown to have standard properties like irreducibility , aperiodicity and harris recurrence under some mild assumptions .
these ensure basic convergence ( ergodicity ) of the kernel .
further the kernel is shown to be geometric ergodic for a large class of target densities on @xmath0 .
this class even contains realistic target densities for which random walk or langevin mh are not geometrically ergodic .
three simulation studies are given to demonstrate the mixing property and superiority of rdmh to standard mh algorithms on real line .
a share - price return data is also analyzed and the results are compared with those available in the literature . * key words * : markov chain monte carlo ; metropolis - hastings algorithm ; random walk algorithm ; langevin algorithm ; multiplicative random walk ; geometric ergodicity ; thick tailed density ; share - price return . *
ams classification number * _ primary _ : 65c05 , 65c40 .
_ secondary _ : 60j10 . .
And you have already written the first three sentences of the full article: suppose @xmath1 is a density on a state - space @xmath2 with respect to some dominating measure @xmath3 . most often the state - space is a subset of the euclidean space and @xmath3 is the lebesgue measure .
in this article we will always assume @xmath3 to be the lebesgue measure .
statisticians main aim is to study the characteristics of the density @xmath1 ..
Please generate the next two sentences of the article | sometimes ( say , in bayesian inference ) @xmath1 may be a complicated ( possibly unnormalized ) density which is not analytically tractable .
so , to study the characteristics of @xmath1 , statisticians try to draw a sample from @xmath1 . |
4,519 | Suppose that you have an abstract for a scientific paper: in the framework of perturbative qcd approach , we calculate the branching ratio and cp asymmetry for @xmath0 and @xmath1 decays . besides the usual factorizable diagrams ,
both non - factorizable and annihilation type contributions are taken into account .
we find that ( a ) the branching ratio of @xmath2 is about @xmath3 ; @xmath4 about @xmath5 ; and ( b ) there are large cp asymmetries in the two processes , which can be tested in the near future lhc - b experiments at cern and btev experiments at fermilab . .
And you have already written the first three sentences of the full article: the rare charmless b meson decays arouse more and more interest , since it is a good place for testing the standard model ( sm ) , studying cp violation and looking for possible new physics beyond the sm .
since 1999 , the b factories in kek and slac collect more and more data sample of rare b decays . in the future cern large hadron collider beauty experiments ( lhc - b ) , the heavier @xmath6 and @xmath7 mesons can also be produced . with the bright hope in lhc - b experiments and btev experiments at fermilab , following a previous study of @xmath8 decay @xcite
, we continue to investigate other @xmath6 rare decays ..
Please generate the next two sentences of the article | the most difficult problem in theoretical calculation of non - leptonic @xmath9 decays is the calculation of hadronic matrix element .
the widely used method is the factorization approach ( fa ) @xcite . |
4,520 | Suppose that you have an abstract for a scientific paper: thurston s boundary to the universal teichmller space @xmath0 is the set of asymptotic rays to the embedding of @xmath0 in the space of geodesic currents ; the boundary is identified with the projective bounded measured laminations @xmath1 of @xmath2 .
we prove that each teichmller geodesic ray in @xmath0 has a unique limit point in thurston s boundary to @xmath0 unlike in the case of closed surfaces . .
And you have already written the first three sentences of the full article: the teichmller space @xmath3 of the unit disk @xmath4 , called the _ universal _ teichm " uller space , consists of all quasisymmetric maps @xmath5 which fix @xmath6 , @xmath7 and @xmath8 on the unit circle @xmath9 ( cf .
the teichm " uller space of an arbitrary hyperbolic surface embeds in @xmath3 as a complex banach submanifold .
thurston s boundary to the universal teichmller space @xmath3 is the space of projective bounded measured laminations @xmath10 of @xmath4 ( cf ..
Please generate the next two sentences of the article | @xcite , @xcite ) .
we study the limits of teichmller geodesic rays on thurston s boundary to @xmath3 . |
4,521 | Suppose that you have an abstract for a scientific paper: we report a correlation between velocity offset ( @xmath0 ) of strong absorption systems and the bolometric luminosity ( @xmath1 ) of quasars in sdss - dr7 . we find that , @xmath2 shows a power law increase with @xmath1 , with a slope @xmath3 .
we find that such a relation of @xmath2 with @xmath1 is expected for outflows driven by scattering of black hole radiation by dust grains , and which are launched from the innermost dust survival radius .
our results indicate that a significant fraction of the strong absorbers , in the range of @xmath4 may be associated with the quasars themselves .
[ firstpage ] galaxies : active quasars : general quasars : absorption lines .
And you have already written the first three sentences of the full article: the study of absorption line systems in the spectra of quasars ( qsos ) has been useful in detecting distant normal field galaxies situated close to the lines of sight of qsos .
conventionally , all such absorbers with velocity @xmath5 @xmath6 relative to the background qso are believed to be associated to the qso itself ( ` associated systems ' ) while those at larger velocity offset are believed to be entirely independent of background qso .
this general belief was questioned recently by the puzzling results on the abundance of strong absorber having equivalent width ( @xmath7 ) more than 1.0 : ( i ) by @xcite where they found @xmath8 time excess of strong absorber towards the @xmath9 ray burst ( grb ) sources relative to qso sight lines ( see also ) , and ( ii ) by , where they found similar excess by a factor of about 2 ( 3 @xmath10 confidence ) towards 45 blazar sight lines ..
Please generate the next two sentences of the article | these counter - intuitive results , have inspired many alternative explanations , such as dust extinction towards qso sight lines which can lower the apparent incidence rate of absorbers , or gravitational lensing which can increase it toward grbs / blazars , but none have been found to explain the above discrepancies .
however the blazars , as a class , are believed to have relativistic jet pointed close to our line of sight . speculated that such powerful jets in the blazars are capable of sweeping sufficiently large column densities of gas ( up to @xmath11 ) and accelerating such clouds to velocities of order @xmath12 , thereby possibly accounting for the excess of absorption systems towards blazars in comparison with qsos . |
4,522 | Suppose that you have an abstract for a scientific paper: we analyze the finite volume spatial convergence combined with exponential time differencing of order one ( etd1 ) for temporal discretization of a non linear advection diffusion reaction equation ( adr ) modeling transport in porous media .
we derive the @xmath0 estimate under the assumption that the non linear reaction is globally lipschitz .
we illustrate the theoretical proof by some applications in 2d and 3d highly anisotropic and heterogeneous porous media including the spe10 case @xcite .
we compute the exponential of the non diagonal matrices arriving in the finite volume spatial discretization with the fast lja points technique and the krylov subspace technique .
finite volume , exponential integrator , porous media , advection diffusion reaction .
And you have already written the first three sentences of the full article: flow and transport are fundamental in many geo - engineering applications , including oil and gas recovery from hydrocarbon reservoirs , groundwater contamination and sustainable use of groundwater resources , storing greenhouse gases ( e.g. co@xmath1 ) or radioactive waste in the subsurface , or mining heat from geothermal reservoirs . in porous media , a single phase transport process is described by the equation @xmath2,\end{aligned}\ ] ] where @xmath3 is an open domain of @xmath4 , @xmath5 is the porosity ( void fraction ) of the rock , and @xmath6 is the symmetric dispersion tensor , @xmath7 is the unknown concentration of the contaminant , @xmath8 the darcy s velocity and @xmath9 the reaction and source term .
+ finite element , finite volume or the combination finite element - finite volume methods are mostly used for space discretization of the problem ( [ adr ] ) while explicit euler , semi implicit and fully implicit methods are usually used for time discretization @xcite . due to time step size constraints , fully implicit scheme is more popular for time discretization for quite a long time compared to explicit euler and semi implicit methods .
this method , however , need at each time step a solution of large systems of nonlinear equations.
Please generate the next two sentences of the article | . this can be the bottleneck in computations . in recent years
, exponential integrators have become an attractive alternative in many evolutions equations @xcite . |
4,523 | Suppose that you have an abstract for a scientific paper: dispersion and absorption properties of a weak probe field in a three - level v - type atomic system is studied . by application of indirect incoherent pump fields
the effect of populating upper levels on optical properties of the atomic medium in presence of a strong coherent pump field is investigated .
it is shown that the slope of dispersion switches from positive to negative just by changing the intensity of the coherent or indirect incoherent pump fields .
it is demonstrated that the absorption - free superluminal and subluminal light propagation appear in this system . .
And you have already written the first three sentences of the full article: in the past few decades , there has been tremendous interests in the study of subluminal and superluminal light propagation @xcite .
the group velocity of light pulse can be reduced in bose - einstein condensate of sodium atom gas @xcite , and in hot gases @xcite , and even halted in vapor of rb atoms @xcite .
also , it can exceed the vacuum light speed , c , and can even become negative @xcite ..
Please generate the next two sentences of the article | these experiments are based on the fact that electromagnetically induced transparency ( eit ) and electro magnetically induced absorption ( eia ) @xcite lead to a dispersion profile with a sharp positive or negative derivative @xcite .
anomalous dispersion was first studied in mechanical oscillators @xcite and was later applied by sommerfeld and brillouin @xcite to light propagation in absorptive opaque materials . |
4,524 | Suppose that you have an abstract for a scientific paper: in this paper we propose an algorithm to generate binary words with no more 0 s than 1 s having a fixed number of 1 s and avoiding the pattern @xmath0 for any fixed @xmath1 .
we will prove that this generation is exhaustive , that is , all such binary words are generated .
* keywords : * binary words , pattern avoiding , exhaustive generation . .
And you have already written the first three sentences of the full article: the problem of determining the appearance of a fixed _ pattern _ in long sequences of observation is relevant in many scientific problems .
for example , in the area of computer network security , the detection of intrusions , which become increasingly frequent , is very important .
intrusion detection is primarily concerned with the detection of illegal activities and acquisitions of privileges that can not be detected by information flow and access control models ..
Please generate the next two sentences of the article | there are several approaches to intrusion detection , but recently this subject has been studied in relation to pattern matching ( see @xcite ) .
this leads to the study of the construction of particular words avoiding a given pattern in an alphabet @xmath2 . |
4,525 | Suppose that you have an abstract for a scientific paper: persistent high - energy emission of magnetars is produced by a plasma corona around the neutron star , with total energy output of @xmath0 erg / s .
the corona forms as a result of occasional starquakes that twist the external magnetic field of the star and induce electric currents in the closed magnetosphere .
once twisted , the magnetosphere can not untwist immediately because of its self - induction .
the self - induction electric field lifts particles from the stellar surface , accelerates them , and initiates avalanches of pair creation in the magnetosphere .
the created plasma corona maintains the electric current demanded by @xmath1 and regulates the self - induction e.m.f . by screening
this corona persists in dynamic equilibrium : it is continually lost to the stellar surface on the light - crossing time @xmath2
s and replenished with new particles .
in essence , the twisted magnetosphere acts as an accelerator that converts the toroidal field energy to particle kinetic energy .
the voltage along the magnetic field lines is maintained near threshold for ignition of pair production , in the regime of self - organized criticality .
the voltage is found to be about @xmath3 gev which is in agreement with the observed dissipation rate @xmath0 erg / s .
the coronal particles impact the solid crust , knock out protons , and regulate the column density of the hydrostatic atmosphere of the star . the transition layer between the atmosphere and the corona is the likely source of the observed 100 kev emission from magnetars .
the corona also emits curvature radiation up to @xmath4 hz and can supply the observed ir - optical luminosity .
example.eps gsave newpath 20 20 moveto 20 220 lineto 220 220 lineto 220 20 lineto closepath 2 setlinewidth gsave .4 setgray fill grestore stroke grestore .
And you have already written the first three sentences of the full article: at least 10% of all neutron stars are born as magnetars , with magnetic fields @xmath5 g. their activity is powered by the decay of the ultrastrong field and lasts about @xmath6 years .
they are observed at this active stage as either soft gamma repeaters ( sgrs ) or anomalous x - ray pulsars ( axps ) @xcite . besides the sporadic x - ray outbursts , a second , persistent
, form of activity has been discovered by studying the emission spectra of magnetars . until recently ,.
Please generate the next two sentences of the article | the spectrum was known to have a thermal component with temperature @xmath7 kev , interpreted as blackbody emission from the star s surface .
the soft x - ray spectrum also showed a tail at @xmath8 kev with photon index @xmath9 . |
4,526 | Suppose that you have an abstract for a scientific paper: in the framework of turbulence dynamo , flow motions amplify a weak seed magnetic field through the stretching of field lines .
although the amplification process has been a topic of active research , less attention has been paid to the length scales of magnetic field . in this paper
, we described a numerical study on characteristic lengths of magnetic field in magnetohydrodynamic turbulence .
we considered the case of very weak or zero mean magnetic field , which is applicable to the turbulence in the intergalactic space .
our findings are as follows .
( 1 ) at saturation , the peak of magnetic field spectrum occurs at @xmath0 , where @xmath1 is the energy injection scale , while the most energy containing scale is @xmath2 .
the peak scale of spectrum of projected , two - dimensional field is @xmath3 .
( 2 ) during the stage of magnetic field amplification , the energy equipartition scale shows a power - law increase of @xmath4 , while the integral and curvature scales show a linear increase .
the equipartition , integral , and curvature scales saturate at @xmath3 , @xmath5 , and @xmath6 , respectively .
( 3 ) the coherence length of magnetic field defined in the faraday rotation measure ( rm ) due to the intergalactic magnetic field ( igmf ) is related to the integral scale .
we presented a formula that expresses the standard deviation of rm , @xmath7 , in terms of the integral scale and rms strength of the igmf , and estimated that @xmath7 would be @xmath8 and @xmath9 a few rad m@xmath10 for clusters and filaments , respectively . .
And you have already written the first three sentences of the full article: it is well established that the universe is permeated with magnetic fields ( see , e.g. , * ? ? ?
* ) , and yet the origin of them is not well understood ( see * ? ? ?
* and references therein ) ..
Please generate the next two sentences of the article | the problem of cosmic magnetism can be divided into two parts - the origin of seed fields and their amplification . in this paper
, we are concerned with the latter . |
4,527 | Suppose that you have an abstract for a scientific paper: we present photometry , photometric redshifts and extra galactic number counts for ultra deep 15 micron mapping of the gravitational lensing cluster abell 2218 ( a2218 ) , which is the deepest image taken by any facility at this wavelength .
this data resolves the cosmic infrared background ( cirb ) beyond the 80% that blank field
_ akari _
surveys aim to achieve . to gain an understanding of galaxy formation and evolution over the age of the universe a necessary step is to fully resolve the cirb , which represents the dust - shrouded cosmic star formation history .
observing through a2218 gives magnifications of up to a factor of 10 , thus allowing the sampling of a more representative spread of high redshift galaxies , which comprise the bulk of the cirb .
19 pointed observations were taken by _ akari _
s irc mir - l channel , and a final combined image with an area of 122.3 square arcminutes and effective integration time of 8460 seconds was achieved .
the 5@xmath0 sensitivity limit is estimated at 41.7 @xmath1jy .
an initial 5@xmath0 catalogue of 565 sources was extracted giving 39 beams per source , which shows the image is confusion limited .
our 15 micron number counts show strong evolution consistent with galaxy evolution models that incorporate downsizing in star formation . .
And you have already written the first three sentences of the full article: our data consists of 19 pointed observation of a2218 , taken with the 15 micron filter of the irc - l @xcite aboard _ akari _ @xcite .
the data was reduced using the standard irc pipeline , version 20070912 . the pipeline s median sky subtraction was utilized but resulted in dark areas , significantly around the brighter sources . to deal with this issue , and the remnants of scattered light persisting post - pipeline , a further median sky subtraction of the background areas was performed .
hot pixels were masked and removed , and the remaining bad pixels were addressed using an idl sigma filtering routine ..
Please generate the next two sentences of the article | figure 1 shows four corresponding postage stamp sections taken from frame 19 illustrating the post - pipeline output , a median filtered mask , the median subtracted result and the sigma filtered result .
the resulting 19 images were aligned with aladin and idl s hastrom , and then average combined to give the final l15 image . |
4,528 | Suppose that you have an abstract for a scientific paper: we present the results of fast temporal optical spectroscopy and photometry of the am her type system by cam obtained in february 1990 and march 1991 .
emission line profiles show a complex structure and are strongly variable .
the radial velocity studies of a sharp component detected in balmer lines in march confirms the non - synchronism of the system .
different possible emitting regions are discussed to explain the characteristics of the multiple line components .
it is shown from a computation of the line velocities and widths that the horizontal stream can not explain the lines of intermediate widths observed in this system .
a critical review of the different estimations of the periods found in by cam is presented .
additional periods are revealed from a re - analysis of previous optical polarimetric and uv spectroscopic data .
we show that because of the slight asynchronism between the white dwarf rotation and the orbital period , significant changes in the accretion geometry introduce a bias in the period determination depending on the length of the observations .
large phase variations are shown to exist which are well reproduced by a phase - drift model in which a magnetic dipole rotates in the orbital frame with a period of [email protected] days . .
And you have already written the first three sentences of the full article: polars ( am her type systems ) are cataclysmic binaries in which a magnetic white dwarf accretes matter from a red dwarf star filling its roche lobe .
the accretion occurs along the magnetic field lines down to the magnetic poles of the white dwarf . the x - rays and the optical polarized flux , both originating close to the surface of the white dwarf
are modulated at the orbital period which proves the synchronism of the white dwarf rotation with the orbital motion ..
Please generate the next two sentences of the article | a comprehensive review of these objects has been done by cropper ( 1990 ) .
+ in the case of by cam , the situation concerning the different periods in the system is not clear . |
4,529 | Suppose that you have an abstract for a scientific paper: recently , adami and coworkers have been able to measure the information content of digital organisms living in their _ avida _ artificial life system .
they show that over time , the organisms behave like maxwell s demon , accreting information ( or complexity ) as they evolve . in _ avida
_ the organisms do nt interact with each other , merely reproduce at a particular rate ( their fitness ) , and attempt to evaluate an externally given arithmetic function in order win bonus fitness points .
measuring the information content of a digital organism is essentially a process of counting the number of genotypes that give rise to the same phenotype .
whilst avidan organisms have a particularly simple phenotype , tierran organisms interact with each other , giving rise to an ecology of phenotypes . in this paper ,
i discuss techniques for comparing pairs of tierran organisms to determine if they are phenotypically equivalent .
i then discuss a method for computing an estimate of the number of phenotypically equivalent genotypes that is more accurate than the `` hot site '' estimate used by adami s group .
finally , i report on an experimental analysis of a tierra run . .
And you have already written the first three sentences of the full article: the issue of what happens to complexity in an evolving system is of great interest . in natural ( biological ) evolution
, the naive view is that life started simple , and evolved ever more complex life forms over time , leading to that pinnacle of complexity , _
homo sapiens_. the end points of that process are of course fixed . in the beginning , life must be simple . in our present era.
Please generate the next two sentences of the article | , there must exist intelligent organisms ( namely us ) pondering over the mystery of how we came to be .
so the _ anthropic principle _ fixes the present day as having complex lifeforms . |
4,530 | Suppose that you have an abstract for a scientific paper: we derive an exact expression for the partition function of the @xmath0 haldane shastry spin chain , which we use to study the density of levels and the distribution of the spacing between consecutive levels .
our computations show that when the number of sites @xmath1 is large enough the level density is gaussian to a very high degree of approximation .
more surprisingly , we also find that the nearest - neighbor spacing distribution is not poissonian , so that this model departs from the typical behavior for an integrable system .
we show that the cumulative spacing distribution of the model can be well approximated by a simple functional law involving only three parameters . .
And you have already written the first three sentences of the full article: the haldane shastry ( hs ) spin chain describes @xmath1 spins equally spaced on a circle with an interaction inversely proportional to the square of their chord distance @xcite .
the original motivation for studying this model is the fact that it possesses an exact jastrow - product ground state , which coincides with the @xmath2 limit of gutzwiller s variational wave function for the hubbard model @xcite , and also with the one - dimensional version of the resonating valence bond state introduced by anderson @xcite . since its very introduction
, the hs spin chain has been extensively studied as a completely integrable model @xcite solvable by the asymptotic bethe ansatz @xcite , whose spinon excitations provide a simple example of a system obeying fractional statistics @xcite ..
Please generate the next two sentences of the article | the energy spectrum of the hs hamiltonian with spin @xmath3 was partially computed in the original papers of haldane and shastry . in a subsequent publication
@xcite , haldane et al . empirically found a complete description of the spectrum for arbitrary spin , and explained its highly degenerate character by the symmetry of the model under the yangian algebra @xmath4 . |
4,531 | Suppose that you have an abstract for a scientific paper: we investigate the backreaction of the quantum fluctuations of a very light ( @xmath0 ) nonminimally coupled spectator scalar field on the expansion dynamics of the universe .
the one - loop expectation value of the energy momentum tensor of these fluctuations , as a measure of the backreaction , is computed throughout the expansion history from the early inflationary universe until the onset of recent acceleration today .
we show that , when the nonminimal coupling @xmath1 to ricci curvature is negative ( @xmath2 corresponding to conformal coupling ) , the quantum backreaction grows exponentially during inflation , such that it can grow large enough rather quickly ( within a few hundred e - foldings ) to survive until late time and constitute a contribution of the cosmological constant type of the right magnitude to appreciably alter the expansion dynamics .
the unique feature of this model is in that , under rather generic assumptions , inflation provides natural explanation for the initial conditions needed to explain the late - time accelerated expansion of the universe , making it a particularly attractive model of dark energy . .
And you have already written the first three sentences of the full article: the recent accelerated expansion of the universe and its cause is one of the most puzzling mysteries in cosmology and physics today . since the observations of type ia supernovae ( sneia ) reported by two groups @xcite
, a lot of observations have been accumulating to indicate that the universe is well described by the @xmath3cdm model ( for recent observational results , see _
e.g. _ ref ..
Please generate the next two sentences of the article | although the cosmological constant ( cc ) gives a good fit to the data and explains well the current cosmic acceleration , future observations promise to provide much tighter constraints of the models .
that motivated theorists to explore other possibilities , which generically came to be known as _ dark energy _ ( de ) ( for a review on dark energy see _ |
4,532 | Suppose that you have an abstract for a scientific paper: this paper describes the sixteen duluth entries in the senseval-2 comparative exercise among word sense disambiguation systems .
there were eight pairs of duluth systems entered in the spanish and english lexical sample tasks .
these are all based on standard machine learning algorithms that induce classifiers from sense - tagged training text where the context in which ambiguous words occur are represented by simple lexical features .
these are highly portable , robust methods that can serve as a foundation for more tailored approaches . .
And you have already written the first three sentences of the full article: the duluth systems in senseval-2 take a supervised learning approach to the spanish and english lexical sample tasks .
they learn decision trees and naive bayesian classifiers from sense - tagged training examples where the context in which an ambiguous word occurs is represented by lexical features . these include unigrams and bigrams that occur anywhere in the context , and co - occurrences within just a few words of the target word .
these are the only types of features used ..
Please generate the next two sentences of the article | there are no syntactic features , nor is the structure or content of wordnet employed . as a result
these systems are highly portable , and can serve as a foundation for systems that are tailored to particular languages and sense inventories . |
4,533 | Suppose that you have an abstract for a scientific paper: in this paper , we prove that relation - extensions of quasi - tilted algebras are 2-calabi - yau tilted . with the objective of describing the module category of a cluster - tilted algebra of euclidean type ,
we define the notion of reflection so that any two local slices can be reached one from the other by a sequence of reflections and coreflections .
we then give an algorithmic procedure for constructing the tubes of a cluster - tilted algebra of euclidean type .
our main result characterizes quasi - tilted algebras whose relation - extensions are cluster - tilted of euclidean type . .
And you have already written the first three sentences of the full article: cluster - tilted algebras were introduced by buan , marsh and reiten @xcite and , independently in @xcite for type @xmath0 as a byproduct of the now extensive theory of cluster algebras of fomin and zelevinsky @xcite . since then , cluster - tilted algebras have been the subject of several investigations , see , for instance , @xcite . in particular , in @xcite
is given a construction procedure for cluster - tilted algebras : let @xmath1 be a triangular algebra of global dimension two over an algebraically closed field @xmath2 , and consider the @xmath1-@xmath1-bimodule @xmath3 , where @xmath4 is the standard duality , with its natural left and right @xmath1-actions .
the trivial extension of @xmath1 by this bimodule is called the _ relation - extension _.
Please generate the next two sentences of the article | @xmath5 of @xmath1 .
it is shown there that , if @xmath1 is tilted , then its relation - extension is cluster - tilted , and every cluster - tilted algebra occurs in this way . |
4,534 | Suppose that you have an abstract for a scientific paper: we explore the high - dimensional chaotic dynamics of the lorenz-96 model by computing the variation of the fractal dimension with system parameters .
the lorenz-96 model is a continuous in time and discrete in space model first proposed by edward lorenz to study fundamental issues regarding the forecasting of spatially extended chaotic systems such as the atmosphere .
first , we explore the spatiotemporal chaos limit by increasing the system size while holding the magnitude of the external forcing constant .
second , we explore the strong driving limit by increasing the external forcing while holding the system size fixed . as the system size is increased for small values of the forcing we find dynamical states that alternate between periodic and chaotic dynamics .
the windows of chaos are extensive , on average , with relative deviations from extensivity on the order of 20% . for intermediate values of the forcing we find chaotic dynamics for all system sizes past a critical value .
the fractal dimension exhibits a maximum deviation from extensivity on the order of 5% for small changes in system size and decreases non - monotonically with increasing system size .
the length scale describing the deviations from extensivity and the natural chaotic length scale are approximately equal in support of the suggestion that deviations from extensivity are due to the addition of chaotic degrees of freedom as the system size is increased . as the forcing is increased at constant system size
the fractal dimension exhibits a power - law dependence .
the power - law behavior is independent of the system size and quantifies the decreasing size of chaotic degrees of freedom with increased forcing which we compare with spatial features of the patterns . .
And you have already written the first three sentences of the full article: a common feature of spatially extended systems that are driven far - from - equilibrium is spatiotemporal chaos where the dynamics are aperiodic in space and time @xcite .
important examples include the dynamics of the atmosphere and climate @xcite ; fluid convection @xcite ; the convection of biological organisms in the oceans @xcite , the transition to chaos in excitable media @xcite ; and the complicated dynamics of systems of reacting , advecting and diffusing chemicals @xcite . despite intense theoretical and experimental investigation
many important challenges remain regarding how to characterize , control , and predict the dynamics of these large complex systems ..
Please generate the next two sentences of the article | a unifying feature of many of these systems is that the dimension of the attractors describing their dynamics in phase space is very large .
this severely limits the use of sophisticated techniques of chaotic time - series analysis @xcite and of powerful geometry based descriptions of dynamical systems @xcite . |
4,535 | Suppose that you have an abstract for a scientific paper: we study the deformation of a cavity around a large projectile moving with subsonic velocity in the cloud of small dust particles . to solve this problem
, we employ the navier stokes equation for a compressible fluid with due regard for friction between dust particles and atoms of neutral gas .
the solutions shows that due to friction , the pressure of a dust cloud at the surface of a cavity around the projectile can become negative , which entails the emergence of a considerable asymmetry of the cavity , i.e. , the cavity deformation .
corresponding threshold velocity is calculated , which is found to decrease with increasing cavity size .
measurement of such velocity makes it possible to estimate the static pressure inside the dust cloud . .
And you have already written the first three sentences of the full article: complex ( dusty ) plasma is a low - temperature plasma including microparticles . due to electron absorption , particles acquire a considerable electric charge .
thus , a strongly coupled coulomb system is formed @xcite .
such plasma represents a natural system which makes it possible to observe various collective phenomena at the level of individual particles . in experimental setups ,.
Please generate the next two sentences of the article | complex plasmas are usually studied in gas discharges at low pressures , e.g. , in radio frequency ( rf ) discharges .
a large homogeneous bulk of complex plasma , which almost fills the entire discharge volume , can be observed under microgravity conditions either in parabolic flights @xcite or onboard the international space station ( iss ) @xcite . in recent studies , |
4,536 | Suppose that you have an abstract for a scientific paper: soft phase lags , in which x - ray pulses in lower energy bands arrive later than pulses in higher energy bands , have been observed in nearly all accretion - powered millisecond pulsars , but their origin remains an open question . in a study of the 2.5 ms accretion - powered pulsar , we report that the magnitude of these lags is strongly dependent on the accretion rate . during the brightest stage of the outbursts from this source , the lags increase in magnitude as the accretion rate drops ; when the outbursts enter their dimmer flaring - tail stage , the relationship reverses .
we evaluate this complex dependence in the context of two theoretical models for the lags , one relying on the scattering of photons by the accretion disk and the other invoking a two - component model for the photon emission . in both cases
, the turnover suggests that we are observing the source transitioning into the `` propeller '' accretion regime . .
And you have already written the first three sentences of the full article: accretion - powered millisecond pulsars ( amps ) provide a unique laboratory for studying the process of disk accretion onto magnetic stars ( @xcite and refrences therein ) .
the @xmath0@xmath1 g stellar magnetic field truncates the accretion disk only a few neutron star radii above the surface , channeling the infalling matter toward the magnetic poles .
the resulting x - ray emitting hot spots and accretion shocks are modulated by the stellar rotation to produce the observed pulsations ..
Please generate the next two sentences of the article | such compact accretion geometry poses a particularly interesting challenge .
we want to understand the details of the interaction between the magnetic field and the disk , and the effects that result from the proximity of different emitting regions . |
4,537 | Suppose that you have an abstract for a scientific paper: recently topological superconducting states has attracted a lot of interest . in this work ,
we consider a topological superconductor with z@xmath0 topological mirror order @xcite and s@xmath1-wave superconducting pairing symmetry , within a two - orbital model originally designed for iron - based superconductivity @xcite .
we predict the existence of gapless edge states .
we also study the local electronic structure around an adsorbed interstitial magnetic impurity in the system , and find the existence of low - energy in - gap bound states even with a weak spin polarization on the impurity .
we also discuss the relevance of our results to the recent stm experiment on fe(te , se ) compound with adsorbed fe impurity @xcite , for which our density functional calculations show the fe impurity is spin polarized .
topological superconductor ( tsc ) has been attracted lots of interest on its potential application to the fault - tolerance quantum computation @xcite and superconducting spintronics @xcite .
the ts can be designed through the interface of a topological insulator with the fully gapped superconductor @xcite or by engineering through the interface of ferromagnetic - superconducting nanostructure under several special conditions @xcite .
most of these efforts were aimed to look for the _ edge states _ and _ in - gap bound states _ in a fully gapped superconductor .
there are two types of edge states for a two - dimensional ( 2d ) tsc .
the first type is a _
chiral _ edge state in a time - reversal - symmetry - broken superconducting pairing state like @xmath2_{\uparrow\uparrow}$ ] @xcite .
the second type is a _ helical _ edge state in a time - reversal - symmetry - invariant pairing state like @xmath3_{\uparrow\downarrow}$ ] ) @xcite .
recently , the crystalline symmetry protected topological phase with mirror chern number has been studied in a triplet pairing state of sr@xmath0ruo@xmath4 @xcite , for which chiral edge states are obtained @xcite .
a realization of....
And you have already written the first three sentences of the full article: the tsc property can be revealed by studying the nature of edge states .
we first calculate the energy dispersion under several conditions . figure [ bands]a shows the evolution of the non - superconducting ( nsc , @xmath26 ) band structure with different values of @xmath14 in brillouin zone ( bz ) corresponding to the 2-site per unit cell . in fig .
[ bands]a , the band crossing below the fermi energy occurs along the @xmath27-@xmath28 direction when there is no existence of the anomalous orbital order ( aoh ) , @xmath29 , and electron and hole pockets are formed at the fermi energy . in the presence of a small value of the aoh term ( @xmath30 ) ,.
Please generate the next two sentences of the article | the band crossing is lifted and the four bands are formed into two disentangled groups . however , the fermi pockets remain .
furthermore , when the topological order is strong enough ( fig . |
4,538 | Suppose that you have an abstract for a scientific paper: a field theory appropriate for magnets that display helical order due to the dzyaloshinsky - moriya mechanism , a class that includes mnsi and fege , is used to derive the phase diagram in a mean - field approximation .
the helical phase , the conical phase in an external magnetic field , and recent proposals for the structure of the a - phase and the non - fermi - liquid region in the paramagnetic phase are discussed .
it is shown that the orientation of the helical pitch vector along an external magnetic field within the conical phase occurs via two distinct phase transitions .
the goldstone modes that result from the long - range order in the various phases are determined , and their consequences for electronic properties , in particular the specific heat , the single - particle relaxation time , and the electrical and thermal conductivities , are derived .
various aspects of the ferromagnetic limit , and qualitative differences between the transport properties of helimagnets and ferromagnets , are also discussed . .
And you have already written the first three sentences of the full article: helical magnets are systems in which long - range magnetic order takes the form of a helix or spiral , such that in any given plane perpendicular to a preferred direction there is ferromagnetic order , but the direction of the magnetization rotates as one goes along the preferred axis .
the pitch vector @xmath0 of the helix points in the preferred direction , and its modulus @xmath1 is the pitch wave number , with @xmath2 equal to the helical wavelength .
one mechanism for stabilizing this type of order over the homogeneous ferromagnet was pointed out by dzyaloshinksky@xcite and moriya.@xcite it relies on the spin - orbit interaction , which can lead , for certain lattice structures , to a term of the form @xmath3 in the hamiltonian or action , with @xmath4 the magnetic order parameter ..
Please generate the next two sentences of the article | the presence of such a chiral term implies that a homogeneously magnetized state can always gain energy by means of a nonzero curl of the magnetization , which leads to a helical ground state . in a rotationally invariant system
the direction of the pitch vector would be arbitrary ( analogous to the arbitrary direction of the magnetization in an isotropic ferromagnet ) . |
4,539 | Suppose that you have an abstract for a scientific paper: packing frustration for confined fluids , i.e. , the incompability between the preferred packing of the fluid particles and the packing constraints imposed by the confining surfaces , is studied for a dense hard - sphere fluid confined between planar hard surfaces at short separations .
the detailed mechanism for the frustration is investigated via an analysis of the anisotropic pair distributions of the confined fluid , as obtained from integral equation theory for inhomogeneous fluids at pair correlation level within the anisotropic percus - yevick approximation . by examining the mean forces that arise from interparticle collisions around the periphery of each particle in the slit
, we calculate the principal components of the mean force for the density profile each component being the sum of collisional forces on a particle s hemisphere facing either surface .
the variations of these components with the slit width give rise to rather intricate changes in the layer structure between the surfaces , but , as shown in this paper , the basis of these variations can be easily understood qualitatively and often also semi - quantitatively .
it is found that the ordering of the fluid is in essence governed locally by the packing constraints at each single solid - fluid interface .
a simple superposition of forces due to the presence of each surface gives surprisingly good estimates of the density profiles , but there remain nontrivial confinement effects that can not be explained by superposition , most notably the magnitude of the excess adsorption of particles in the slit relative to bulk .
published as j. chem .
phys . * 141 * , 094501 ( 2014 ) . .
And you have already written the first three sentences of the full article: spatial confinement of condensed matter is known to induce a wealth of exotic crystalline structures.@xcite in essence this can be attributed to a phenomenon coined packing frustration ; an incompability between the preferred packing of particles whether atoms , molecules , or colloidal particles and the packing constraints imposed by the confining surfaces . as an illustrative example , we can consider the extensively studied system of hard spheres confined between planar hard surfaces at a close separation of about five particle diameters or less .
this is a convenient system for studies on packing frustration , because its phase diagram is determined by entropy only .
while the phase diagram of the bulk hard - sphere system is very simple,@xcite the dense packing of hard - sphere particles in narrow slits has been found to induce more than twenty novel thermodynamically stable crystalline phases , including exotic ones such as buckled and prism - like crystalline structures.@xcite in the case of spatially confined fluids , the effects of packing frustration are more elusive ..
Please generate the next two sentences of the article | nevertheless , extensive studies on the fluid s equilibrium structure has brought into evidence this phenomenon ; confinement - induced ordering of the fluid is suppressed when the short - range order preferred by the fluid s constituent particles is incompatible with the confining surface separation ( see , e.g. , ref . for illustrative examples ) .
packing frustration also influences other properties of the confined fluid , such as a strongly suppressed dynamics because of caging effects.@xcite however , little is known to date about the underlying mechanisms of frustration in spatially confined fluids . |
4,540 | Suppose that you have an abstract for a scientific paper: ballistic particles interacting with irregular surfaces are representative of many physical problems in the knudsen diffusion regime . in this paper ,
the collisions of ballistic particles interacting with an irregular surface modeled by a quadratic koch curve , are studied numerically .
the @xmath0 moments of the source spatial distribution of collision numbers @xmath1 are characterized by a sequence of `` collision exponent '' @xmath2 .
the measure @xmath1 is found to be multifractal even when a random micro - roughness ( or random re - emission ) of the surface exists .
the dimensions @xmath3 , obtained by a legendre transformation from @xmath2 , consist of two parabolas corresponding to a trinomial multifractal .
this is demonstrated for a particular case by obtaining an exact @xmath3 for a multiplicative trinomial mass distribution .
the trinomial nature of the multifractality is related to the type of surface macro - irregularity considered here and is independent of the micro - roughness of the surface which however influence the values of @xmath4 and @xmath5 .
the information dimension @xmath6 increases significantly with the micro - roughness of the surface .
interestingly , in contrast with this point of view , the surface seems to work uniformly .
this correspond to an absence of screening effects in knudsen diffusion . . .
And you have already written the first three sentences of the full article: multifractals appear in a wide range of situations like energy dissipation in turbulent flows @xcite , electronic eigenstates at metal insulator transition @xcite , fluctuations in finance @xcite , dynamics of human heartbeat @xcite and many others .
recently , multifractal behavior of the first passage time has been studied in the transport of diffusing particles on a @xmath7 sierpinski gasket with absorbing and reflecting barriers @xcite .
our interest is to investigate the multifractal properties associated with the collision spectrum of ballistic trajectories of point particles interacting with irregular surfaces ..
Please generate the next two sentences of the article | the emergence of the concept of fractal geometry has provided an efficient tool to model the influence of strong geometrical irregularity on various physical and chemical processes @xcite .
ballistic trajectories in systems with irregular geometry are representative of several physical situations . |
4,541 | Suppose that you have an abstract for a scientific paper: emission from high-@xmath0 galaxies must unquestionably contribute to the near - infrared background ( nirb ) . however , this contribution has so far proven difficult to isolate even after subtracting the resolved galaxies to deep levels .
remaining nirb fluctuations are dominated by unresolved low-@xmath0 galaxies on small angular scales , and by an unidentified component with unclear origin on large scales ( @xmath1 ) . in this paper , by analyzing mock maps generated from semi - numerical simulations and empirically determined @xmath2 relations , we find that fluctuations associated with galaxies at @xmath3 amount to several percent of the unresolved nirb flux fluctuations .
we investigate the properties of this component for different survey areas and limiting magnitudes . in all cases ,
we show that this signal can be efficiently , and most easily at small angular scales , isolated by cross - correlating the source - subtracted nirb with lyman break galaxies ( lbgs ) detected in the same field by hst surveys .
this result provides a fresh insight into the properties of reionization sources .
cosmology : diffuse radiation - dark ages ; reionization , first stars infrared : diffuse - background galaxies : high - redshift .
And you have already written the first three sentences of the full article: the cosmic infrared background ( cib or cirb ) contains a considerable fraction of the collective radiation emitted by stars through the cosmic time .
stars in the epoch of reionization ( eor ) have the bulk of their radiation redshifted into the near - infrared band ( @xmath40.7 - 5 @xmath5 m ) and the cib measured in this band is specifically named near - infrared background " ( nirb ) . as such
, the nirb offers a unique opportunity to study faint high-@xmath0 galaxies that remain largely undetected in deep galaxy surveys ( see e.g. @xcite ) ..
Please generate the next two sentences of the article | this is particularly important as these objects are commonly believed to provide most of the ionizing power that drives cosmic reionization @xcite . besides
, the nirb might also help characterizing the stellar populations of the first cosmic systems @xcite . |
4,542 | Suppose that you have an abstract for a scientific paper: in 1987 , c. sabbah proved the existence of bernstein - sato polynomials associated with several analytic functions . the purpose of this article is to give a more elementary and constructive proof of the result of c. sabbah based on the notion of the analytic grbner fan of a @xmath0-module . .
And you have already written the first three sentences of the full article: fixons @xmath1 et @xmath2 deux entiers et @xmath3 .
soient @xmath4 et @xmath5 deux systmes de variables . on se donne @xmath6 .
notons @xmath7 lanneau des oprateurs diffrentiels coefficients dans @xmath8 ..
Please generate the next two sentences of the article | pour @xmath9={\mathbb{c}}[s_1,\ldots , s_p]$ ] , considrons lidentit suivante : @xmath10 f^{s+v},\ ] ] o @xmath11 .
un polynme @xmath12 vrifiant une telle identit est appel polynme de bernstein - sato ( associ @xmath13 ) . |
4,543 | Suppose that you have an abstract for a scientific paper: we have applied the `` synthetic field method '' on a sample of 20 nearby galaxies in order to determine the opacity of their disks .
we present preliminary results on the radial dependence of cold dust absorption for 3 examples .
the spirals ngc4535 and ngc4725 show significant absorption at a half - light radius . ugc2302 , a lsb galaxy , shows much less opacity . # 1_#1 _ # 1_#1 _ = # 1 1.25 in .125 in .25 in .
And you have already written the first three sentences of the full article: the synthetic field method ( sfm ) was developed by gonzlez et al .
( 1998 ) as a technique for determining the average opacity through the disk of a nearby spiral by counting more distant background galaxies .
this number is compared with those of `` synthetic fields '' , a known wfpc2 deep field , dimmed by a certain opacity , added to the foreground galaxy image ..
Please generate the next two sentences of the article | gonzlez et al . ( 2003 ) examined the application of the method and concluded that the optimum results with hst / wfpc2 imaging would be obtained on fornax and virgo cluster galaxies , with the accuracy degrading for galaxies much closer or more distant .
our sample was drawn from the hst archives , in part from the cepheid distance scale hst key project sample . |
4,544 | Suppose that you have an abstract for a scientific paper: the burst and transient source experiment ( batse ) aboard cgro monitored the whole sky through 8 nai(tl ) crystal scintillators sensitive in the 20 kev - 2 mev energy band continuously from april 1991 until june 2000 .
results are presented on the long term variabilty observed in the brightest active galactic nuclei ( agn ) present in the batse data archive .
this was achieved through the application of the earth occultation technique to data flat - fielded using the batse mass model .
removal of the temporal background variations from the data should allow a more sensitive extraction of source parameters .
analysis of the general trends of the 9-year light curves are also presented .
[ 2004/02/13 1.1 ( pwd ) ] .
And you have already written the first three sentences of the full article: the primary mission of the batse instrument was to detect and locate @xmath0-ray bursts .
while the 8 detectors had no intrinsic positional sensitivity , burst positions were obtained by triangulation between detectors .
it was realised , prior to launch , that persistent sources of @xmath0-rays could also be observed by using the earth occultation technique @xcite ..
Please generate the next two sentences of the article | this method calculates the source flux by measuring the step in the count rate of each batse detector as a source rises or sets below the earth s limb .
mass modelling is a technique to simulate the background radiation experienced by a space craft @xcite . |
4,545 | Suppose that you have an abstract for a scientific paper: we study the role of diquarks in light baryons through point to point baryon correlators .
we contrast results from quenched simulations with ones with two flavors of dynamical overlap fermions .
the scalar , pseudoscalar and axial vector diquarks are combined with light quarks to form color singlets . the quenched simulation shows large zero mode effects in correlators containing the scalar and pseudoscalar diquark .
the two scalar diquarks created by @xmath0 and @xmath1 lead to different behavior in baryon correlators , showing that the interaction of diquarks with the third light quark matters : we do not see an isolated diquark . in our quark mass range , the scalar diquark created by @xmath0 seems to play a greater role than the others . .
And you have already written the first three sentences of the full article: in the conventional quark model , a baryon is a bound state of three more - or - less equivalent valence quarks .
however , there are variants of the quark model in which interactions give rise to a quark - diquark structure for the baryon , where the binding of two of the quarks in the baryon is different from the bound state properties of the third quark . for a review of diquark phenomenology ,
see @xcite ..
Please generate the next two sentences of the article | one would like to understand the properties of diquark correlations ( if any ) directly from qcd . since this is a problem of the long distance behavior of the strong interactions , perturbation theory is not applicable .
lattice qcd is a potential source of information about diquark structures , and the subject has been visited many times in lattice simulations @xcite . |
4,546 | Suppose that you have an abstract for a scientific paper: we study the minimization problem of a non - convex sparsity promoting penalty function , the transformed @xmath0 ( tl1 ) , and its application in compressed sensing ( cs ) .
the tl1 penalty interpolates @xmath1 and @xmath0 norms through a nonnegative parameter @xmath2 , similar to @xmath3 with @xmath4 $ ] .
tl1 is known in the statistics literature to enjoy three desired properties : unbiasedness , sparsity and lipschitz continuity .
we first consider the constrained minimization problem and prove the uniqueness of global minimizer and its equivalence to @xmath1 norm minimization if the sensing matrix @xmath5 satisfies a restricted isometry property ( rip ) and if @xmath6 , where @xmath7 depends only on @xmath5 . though result contains the well - known equivalence of @xmath0 norm and @xmath1 norm , in the limit @xmath8 , the main difficulty is in treating the lack of scaling property of the tl1 penalty function . for a general sensing matrix @xmath5
, we show that the support set of a local minimizer corresponds to linearly independent columns of @xmath5 , and recall sufficient conditions for a critical point to be a local minimum .
next , we present difference of convex algorithms for tl1 ( dcatl1 ) in computing tl1-regularized constrained and unconstrained problems in cs .
the dcatl1 algorithm involves outer and inner loops of iterations , one time matrix inversion , repeated shrinkage operations and matrix - vector multiplications . for the unconstrained problem , we prove convergence of dcalt1 to a stationary point satisfying the first order optimality condition . finally in numerical experiments ,
we identify the optimal value @xmath9 , and compare dcatl1 with other cs algorithms on two classes of sensing matrices : gaussian random matrices and over - sampled discrete cosine transform matrices ( odct ) . among existing algorithms ,
the iterated reweighted least squares method based on @xmath10 norm is the best in sparse recovery for gaussian matrices , and the dca algorithm based on....
And you have already written the first three sentences of the full article: compressed sensing @xcite has generated enormous interest and research activities in mathematics , statistics , signal processing , imaging and information sciences , among numerous other areas .
one of the basic problems is to reconstruct a sparse signal under a few linear measurements ( linear constraints ) far less than the dimension of the ambient space of the signal . consider a sparse signal @xmath13 , an @xmath14 sensing matrix a and an observation @xmath15 , @xmath16 , such that : @xmath17 where @xmath18 is an @xmath19-dimensional observation error .
if @xmath20 is sparse enough , it can be reconstructed exactly in the noise - free case and in stable manner in the noisy case provided that the sensing matrix @xmath5 satisfies certain incoherence or the restricted isometry property ( @xmath21 ) @xcite ..
Please generate the next two sentences of the article | the direct approach is @xmath1 optimization , including constrained formulation : @xmath22 and the unconstrained @xmath1 regularized optimization : @xmath23 with positive regularization parameter @xmath24 . since minimizing @xmath1 norm
is np - hard @xcite , many viable alternatives are available . greedy methods ( matching pursuit @xcite , othogonal matching pursuits ( omp ) @xcite , and regularized omp ( romp ) @xcite ) work well if the dimension @xmath19 is not too large . for the unconstrained problem ( [ eq : l0 uncons ] ) , the penalty decomposition method @xcite replaces the term @xmath25 by @xmath26 , and minimizes over @xmath27 for a diverging sequence @xmath28 . |
4,547 | Suppose that you have an abstract for a scientific paper: this paper presents some parallel developments in quiver / dimer models , hypergeometric systems and dessins denfants .
it demonstrates that the setting in which gelfand , kapranov and zelevinsky have formulated the theory of hypergeometric systems , provides also a natural setting for dimer models .
the fast inverse algorithm of @xcite and the untwisting procedure of @xcite are recasted in this more natural setting and then immediately produce from the quiver data the kasteleyn matrix for dimer models , which is best viewed as the bi - adjacency matrix for the untwisted model .
some perfect matchings in the dimer models are direct reformulations of the triangulations in gkz theory and the rule which maps triangulations to the vertices of the secondary polygon extends to a rule for mapping perfect matchings to lattice points in the secondary polygon . finally it is observed in many examples and then conjectured to hold in general , that the determinant of the kasteleyn matrix with suitable weights becomes after a simple transformation equal to the principal @xmath0-determinant in gkz theory .
illustrative examples are distributed throughout the text . .
And you have already written the first three sentences of the full article: in the last decade interesting correspondences were discovered relating quiver gauge theories , lattice polygons and calabi - yau singularities .
the motivation and evolution of these ideas in physics are well - documented in many articles ; e.g. @xcite . in the present paper
we want to put some aspects of these correspondences from physics alongside the hypergeometric systems in two variables of gelfand , kapranov , zelevinsky @xcite and the dessins denfants of grothendieck et al ..
Please generate the next two sentences of the article | this reveals intriguing connections between these fields .
the beautiful insight of gelfand , kapranov and zelevinsky was that hypergeometric structures greatly simplify if one introduces extra variables and balances this with an appropriate torus action @xcite . in order to profit from the simplication they developed tools like the _ secondary fan , secondary polytope _ and _ |
4,548 | Suppose that you have an abstract for a scientific paper: as a minimal mathematical model generating cascade analogous to that of the navier - stokes turbulence in the inertial range , we propose a one - dimensional partial - differential - equation model that conserves the integral of the squared vorticity analogue ( enstrophy ) in the inviscid case . with a large - scale random forcing and small viscosity ,
we find numerically that the model exhibits the enstrophy cascade , the broad energy spectrum with a sizable correction to the dimensional - analysis prediction , peculiar intermittency and self - similarity in the dynamical system structure . .
And you have already written the first three sentences of the full article: one way to tackle the problem of fluid turbulence is to study its model with a drastically reduced degrees of freedom .
these models are made in mostly phenomenological ways to qualitatively have a few , selected aspects of turbulence .
celebrated models include the burgers equation @xcite and the shell models @xcite , which are certainly more amenable to analytical and numerical studies ..
Please generate the next two sentences of the article | another family tree of these models stems from the constantin - lax - majda ( clm ) model @xcite .
we find a turbulent solution of this model family for the first time and discuss its relevance to two - dimensional navier - stokes turbulence . |
4,549 | Suppose that you have an abstract for a scientific paper: we summarize recent attempts to extract characteristics of non - perturbative vacuum structure from lattice measurements of the gauge invariant field strength correlator . as an alternative to cooling , we propose to apply the renormalization group ( rg ) smoothing method in lattice studies . for pure @xmath0
gauge theory we present magnetic and electric correlation lengths and condensates related to various correlators over a temperature range of @xmath1 .
+ pacs : 11.15.ha , 12.38.gc , 11.15.kc , 11.10.wx .
And you have already written the first three sentences of the full article: quantum chromodynamics ( qcd ) owes its confining property to non - perturbative structures of its groundstate which are , after many years of research , not yet uniquely identified .
( for a recent overview of competing pictures see e.g. @xcite ) . in a more pragmatic attitude , the stochastic vacuum model ( svm ) @xcite describes the vacuum structure in terms of a few vacuum correlation functions and points out which are related to confinement . that only few correlators should characterize
the vacuum is the consequence of a truncation of the hierarchy of correlation functions , essentially due to a postulate made within the svm that the gauge fields are gaussian random processes in euclidean space - time . in this framework ,.
Please generate the next two sentences of the article | the correlators enter , and relate to each other , various phenomenological predictions . particularly interesting
( exhausting , in the case of pure gluodynamics ) is the gauge invariant gluon field strength correlator in euclidean space ( and its continuation to minkowski space ) . according to the svm , part of the euclidean field strength correlator at zero temperature |
4,550 | Suppose that you have an abstract for a scientific paper: we consider the general case of @xmath0 dual pairs of type iia / heterotic string theories in four dimensions .
we show that if the type iia string in this pair can be viewed as having been compactified on a calabi - yau manifold in the usual way then this manifold must be of the form of a k3 fibration .
we also see how the bound on the rank of the gauge group of the perturbative heterotic string has a natural interpretation on the type iia side .
epsf # 1date_#1 _ # 1thefnmarkfootnotetext1991 _ mathematics subject classification .
_ # 1 # 1thefnmarkfootnotetext _ key words and phrases .
_ # 1 ps .
@firstpageps .
@empty oddhead evenheadoddhead # 1 .
And you have already written the first three sentences of the full article: 40004000 = 1000 = ifundefinedreset@font@font footnotetext#1 tempcntc citex[#1]#2@fileswauxout tempcnta@tempcntb@neciteaciteforciteb:=#2citeo#1 citeotempcnta > tempcntbcitea citea , m tempcnta = tempcntbtempcnta # 1 o p # 1#1 # 1 # 1 # 1 # 1 # 1#2 # 1#2_#1f_#2 # 1#1 # 1#1 _ # 1@xmath1 # 1 _ 0
recently , the quantum properties of @xmath0 supersymmetric field theories have been under active investigation .
in particular , seiberg and witten @xcite analyzed an asymptotically free @xmath2 yang - mills theory and determined the leading contribution of the low energy effective action for all values of the gauge coupling ..
Please generate the next two sentences of the article | it turns out that in the strong coupling region no massless @xmath2 gauge bosons exist ; instead magnetic monopoles become massless and the effective low energy theory is best described by a weakly coupled dual @xmath3 magnetic gauge theory .
these developments lead to intensive attempts to uncover the same physical phenomenon in string theory and study its gravitational and `` stringy '' generalizations . |
4,551 | Suppose that you have an abstract for a scientific paper: we report a study of the normal- and superconducting - state electronic properties of the centrosymmetric compound srpt@xmath0p via @xmath1p nuclear - magnetic - resonance ( nmr ) and magnetometry investigations .
essential features such as a sharp drop of the knight shift at @xmath2 and an exponential decrease of the nmr spin - lattice relaxation ratio @xmath3 below @xmath4 are consistent with an @xmath5-wave electron pairing in srpt@xmath0p , although a direct confirmation in the form of a hebel - slichter - type peak is lacking .
normal - state nmr data at @xmath6k indicate conventional features of the conduction electrons , typical of simple metals such as lithium or silver .
our data are finally compared with available nmr results for the noncentrosymmetric superconductors lapt@xmath0si and cept@xmath0si , which adopt similar crystal structures . .
And you have already written the first three sentences of the full article: the continuing search for new superconductors has recently resulted in the identification of a new family of superconducting phosphide compounds with the chemical composition _ _ a__pt@xmath0p ( _ a _ = sr , ca , or la).@xcite these materials , whose superconductivity has been claimed to be driven by conventional electron - phonon interactions , adopt a distorted anti - perovskite structure , resembling the structure of several noncentrosymmetric superconductors , such as lapt@xmath0si or cept@xmath0si.@xcite contrary to the latter , however , srpt@xmath0p exhibits an inversion center due to the staggered arrangement of pt octahedra .
noncentrosymmetric superconductors , characterized by antisymmetric spin - orbit couplings , are currently the subject of intense research.@xcite therefore , a comparative study of their centrosymmetric counterparts is of particular interest .
indeed , the sr - based compound of the new family , with a critical temperature @xmath7k , has already been investigated in some detail ..
Please generate the next two sentences of the article | the first study included measurements of the specific heat @xmath8 and hall resistivity @xmath9.@xcite the specific - heat data were interpreted as indicating a strong electron - phonon coupling with a relatively large ratio @xmath10 , and a fully - gapped excitation spectrum below @xmath4 with a zero - temperature gap value @xmath11 mev .
the nonlinear magnetic field dependence of hall resistivity was attributed to the presence of multiple fermi - surface pockets . |
4,552 | Suppose that you have an abstract for a scientific paper: we perform model independent and model dependent analyses of solar neutrino data including the neutral current event rate from sno .
the inclusion of the first sno nc data in the model independent analysis determines the allowed ranges of @xmath0 flux normalisation and the @xmath1 survival probability more precisely than what was possible from the sk and sno cc combination .
we perform global @xmath2 oscillation analyses of solar neutrino data using the nc rate instead of the ssm prediction for the @xmath0 flux , in view of the large uncertainty in the latter .
the lma gives the best solution , while the low solution is allowed only at the @xmath3 level .
* implications of the first neutral current data from sno for solar neutrino oscillation * abhijit bandyopadhyay@xmath4 , sandhya choubey@xmath5 , srubabati goswami@xmath6 , d.p .
roy@xmath7 @xmath4saha institute of nuclear physics , bidhannagar , kolkata 700 064 , india + @xmath5 department of physics and astronomy , university of southampton , highfield , southampton s017 1bj , uk + @xmath8 harish - chandra research institute , chhatnag road , jhusi , allahabad - 211 - 019 , india @xmath9tata institute of fundamental research , homi bhabha road , mumbai 400 005 , india + @xmath10physics department , university of california , riverside , ca 92521,usa the neutral current results from the sudbury neutrino observatory measures for the first time the total flux of @xmath0 neutrinos coming from the sun @xcite . in a recent paper @xcite we had examined the role of the anticipated nc data from sno in enhancing our understanding of the solar neutrino problem .
the sno nc rate can be expressed in terms of sno cc and sk elastic scattering rates as @xcite r^nc_sno = r^cc_sno + ( r^el_sk - r^cc_sno)/r , [ one ] where @xmath11 for a threshold energy of 5 mev ( including the detector resolutions and the radiative corrections to @xmath12 scattering cross - sections ) .
all the rates are defined with respect to the bbp2000 standard solar model ( ssm )....
And you have already written the first three sentences of the full article: for the general case of @xmath1 transition into a combination of @xmath27 ( @xmath28 ) and @xmath29 ( @xmath30 ) states one can write the sk , sno cc and sno nc rates as r^el_sk & = & f_b p_ee + f_b r p_ea , [ two ] + r^cc_sno & = & f_b p_ee , [ three ] + r^nc_sno & = & f_b ( p_ee + p_ea ) , [ four ] where @xmath16 and @xmath31 denote the probabilities folded with the detector response function @xcite and averaged over energy . to extract a model independent bound on @xmath16 one has to ensure an equality of the response functions which amounts to slight adjustment of the sk threshold energy and the rate @xcite .
our approach is slightly different .
we treat @xmath16 to be effectively energy independent ..
Please generate the next two sentences of the article | the sk spectrum data indicates a flat probability down to 5 mev @xcite .
this is corroborated by sno @xcite which now has a threshold of 5 mev for kinetic energy of the observed electron . |
4,553 | Suppose that you have an abstract for a scientific paper: it has been recently pointed out that removing the axial symmetry in the `` multi - angle effects '' associated with the neutrino - neutrino interactions for supernova ( sn ) neutrinos , a new multi - azimuthal - angle ( maa ) instability would arise . in particular , for a flux ordering @xmath0 , as expected during the sn accretion phase , this instability occurs in the normal neutrino mass hierarchy .
however , during this phase the ordinary matter density can be larger than the neutrino one , suppressing the self - induced conversions . at this regard
, we investigate the matter suppression of the maa effects , performing a linearized stability analysis of the neutrino equations of motion , in the presence of realistic sn density profiles .
we compare these results with the numerical solution of the sn neutrino non - linear evolution equations .
assuming axially symmetric distributions of neutrino momenta we find that the large matter term strongly inhibits the maa effects .
in particular , the hindrance becomes stronger including realistic forward - peaked neutrino angular distributions . as a result , in our model for a @xmath1 @xmath2 iron - core sne
, maa instability does not trigger any flavor conversion during the accretion phase . instead ,
for a @xmath3 @xmath2 o - ne - mg core sn model , with lower matter density profile and less forward - peaked angular distributions , flavor conversions are possible also at early times . .
And you have already written the first three sentences of the full article: the flavor evolution of supernova ( sn ) neutrinos , is strongly impacted by the self - induced effects , associated with instabilities induced by the the neutrino - neutrino interactions in the deepest stellar regions @xcite ( see also @xcite for a recent review ) . in this context a key ingredient in the characterization of these effects is related to the current - current nature of low - energy weak interactions , which implies a `` multi - angle term '' @xcite @xmath4 , where @xmath5 is the neutrino velocity @xcite . till recently
, all studies have assumed the axial symmetry for this term , that would then depend only on the zenith - angle .
it has been shown that the `` multi - zenith - angle '' ( mza ) term in some cases can hinder the maintenance of the coherent oscillation behavior for different neutrino modes @xcite . a valuable tool to diagnose the possible instabilities of a dense neutrino gas is given by the linearized stability analysis of the neutrino equations of motion ..
Please generate the next two sentences of the article | the linearized equations including generic azimuthal and zenith angle distributions for neutrinos were first worked out in @xcite . then , the formalism for the azimuthal symmetric case was further developed in @xcite .
the stability method would allow one to determine the possible onset of the flavor conversions , seeking for an exponentially growing solution of the eigenvalue problem , associated with the linearized equations of motion for the neutrino ensemble . |
4,554 | Suppose that you have an abstract for a scientific paper: the parameter dependence of the various attractive solutions of the three variable nonlinear lorenz model equations for thermal convection in rayleigh - bnard flow is studied .
its bifurcation structure has commonly been investigated as a function of @xmath0 , the normalized rayleigh number , at fixed prandtl number @xmath1 .
the present work extends the analysis to the entire @xmath2 parameter plane .
an onion like periodic pattern is found which is due to the alternating stability of symmetric and non - symmetric periodic orbits .
this periodic pattern is explained by considering non - trivial limits of large @xmath0 and @xmath1 .
in addition to the limit which was previously analyzed by sparrow , we identify two more distinct asymptotic regimes in which either @xmath3 or @xmath4 is constant . in both limits the dynamics is approximately described by airy functions whence the periodicity in parameter space can be calculated analytically .
furthermore , some observations about sequences of bifurcations and coexistence of attractors , periodic as well as chaotic , are reported . .
And you have already written the first three sentences of the full article: the nonlinear coupled set of three odes [ lorenz ] x = -x + y , y = r x - y -xz , z = -bz + xy , was first derived by berry saltzman and edward lorenz @xcite as a model for thermal convection between two plates perpendicular to the direction of the earth s gravitational force .
it has three control parameters .
first , there is the normalized temperature difference @xmath5 between the hotter lower plate and the colder upper one ..
Please generate the next two sentences of the article | @xmath6 is the temperature difference at the onset of convection .
@xmath7 , the rayleigh number , is the dimensionless temperature difference . |
4,555 | Suppose that you have an abstract for a scientific paper: in an r - parity violating supersymmetric scenario , the lightest neutralino @xmath0 is no longer a stable particle .
we calculate the branching ratio for the decay mode @xmath1 which occurs at the one - loop level . taking into account bilinear as well as trilinear lepton number violating interactions as the sources of r - parity violation
, we make a detailed scan of the parameter space , both with and without gaugino mass unification and including the constraints on the neutrino sector from the recent superkamiokande results .
this study enables one to suggest interesting experimental signals distinguishing between the two types of r - parity breaking , and also to ascertain whether such radiative decays can give rise to collider signals of the type @xmath2 + @xmath3 from pair - produced neutralinos .
= -6pt = -1 in = 6.5 in = 9.4 in = 0.75 in 2 q^2 // mri - phy / p990307 + march , 1999 + hep - ph/9903418 * radiative decay of the lightest neutralino in an r - parity violating supersymmetric theory * + biswarup mukhopadhyaya and sourov roy + _ mehta research institute , + chhatnag road , jhusi , allahabad - 211 019 , india _
+ 1 true cm pacs nos . : 12.60.jv , 13.10.+q , 14.80.ly .
And you have already written the first three sentences of the full article: decay of a heavy particle with a photon in the final state can often lead to experimental signals for physics beyond the standard model .
recent literature contains many studies , both experimental and theoretical , devoted to signals of the type @xmath2 + @xmath3 , @xmath4 + @xmath3 etc .
@xcite in the context of various new physics scenarios . a rather large fraction of such studies.
Please generate the next two sentences of the article | are concerned with supersymmetric ( susy ) @xcite theories .
for example , in models with gauge mediated supersymmetry breaking ( gmsb)@xcite , the decay of the lightest neutralino ( @xmath0 ) ( next - to - lightest supersymmetric particle in these models ) into a photon and a gravitino can give rise to @xmath2 + @xmath3 ( or @xmath4 + @xmath3 ) which can have substantial event rates even after subtracting the standard model backgrounds . the signal @xmath2 + @xmath3 |
4,556 | Suppose that you have an abstract for a scientific paper: we present the discovery of the vela - like radio pulsar j1856 + 0245 in the arecibo palfa survey .
psr j1856 + 0245 has a spin period of 81ms , a characteristic age of 21kyr , and a spin - down luminosity @xmath0ergs s@xmath1 .
it is positionally coincident with the tev @xmath2-ray source hess j1857 + 026 , which has no other known counterparts .
young , energetic pulsars create wind nebulae , and more than a dozen pulsar wind nebulae have been associated with very - high - energy ( 100gev@xmath3100tev ) @xmath2-ray sources discovered with the hess telescope . the @xmath2-ray emission seen from hess j1857 + 026 is potentially produced by a pulsar wind nebula powered by psr j1856 + 0245 ; faint x - ray emission detected by _
asca _ at the pulsar s position supports this hypothesis .
the inferred @xmath2-ray efficiency is @xmath4% ( @xmath5tev , for a distance of 9kpc ) , comparable to that observed in similar associations . .
And you have already written the first three sentences of the full article: in the last few years , approximately 40 new galactic sources of very - high - energy ( vhe ) @xmath2-ray emission ( 100gev@xmath3100tev ) have been discovered using the high energy stereoscopic system ( hess ) cherenkov telescope array ( e.g. , * ? ? ?
these are an exciting new population of sources , which give new insight into non - thermal particle acceleration in galactic objects such as neutron stars , supernova remnants , and x - ray binaries . thus far ,
close to half of these sources have been established or suggested as being associated with the pulsar wind nebulae ( pwne ) of young pulsars , either through direct detection of a pwn or positional coincidence with a young pulsar which is presumed to have a pwn ( table [ tab : assoc ] ) ..
Please generate the next two sentences of the article | clearly , pwne are now an important and well - established galactic source of vhe @xmath2-rays . since both young pulsars and their pwne can be very dim , many of the galactic hess sources without identified counterparts ( e.g. , * ? ? ?
* ) may be pwne , potentially detectable via deep radio or x - ray observations . in general , |
4,557 | Suppose that you have an abstract for a scientific paper: we study the einstein - yang - mills equations in a 6-dimensional space - time .
we make a self - consistent static , spherically symmetric ansatz for the gauge fields and the metric .
the metric of the manifold associated with the two extra dimensions contains off - diagonal terms .
the classical equations are solved numerically and several branches of solutions are constructed .
we also present an effective 4-dimensional action from which the equations can equally well be derived .
this action is a standard einstein - yang - mills - higgs theory extended by three scalar fields .
two of the scalar fields are interpreted as dilatons , while the one associated with the off - diagonal term of the metric induces very specific interactions . .
And you have already written the first three sentences of the full article: in an attempt to unify electrodynamics and general relativity , kaluza introduced an extra , a fifth dimension @xcite and assumed all fields to be independent of the extra dimension .
klein @xcite followed this idea , however , he assumed the fifth dimension to be compactified on a circle of planck length .
the resulting theory describes @xmath0-dimensional einstein gravity plus maxwell s equations ..
Please generate the next two sentences of the article | one of the new fields appearing in this model is the dilaton , a scalar companion of the metric tensor . in an analogue way
, this field arises in the low energy effective action of superstring theories and is associated with the classical scale invariance of these models @xcite . both string theories @xcite as well as |
4,558 | Suppose that you have an abstract for a scientific paper: within dynamical mean - field theory , we study the metal - insulator transition of a twofold orbitally degenerate hubbard model as a function of a splitting @xmath0 of the degeneracy .
the phase diagram in the @xmath1 plane exhibits two - band and one - band metals , as well as the mott insulator .
the correlated two - band metal is easily driven to the insulator state by a strikingly weak splitting @xmath2 of the order of the kondo - peak width @xmath3 , where @xmath4 is the metal quasiparticle weight .
the possible relevance of this result to the insulator - metal transition in the orthorhombic expanded fulleride nh@xmath5k@xmath5c@xmath6 is discussed . .
And you have already written the first three sentences of the full article: strong electron correlations in multi - band , orbitally degenerate systems represent an important current theoretical challenge . a lively experimental playground for that is provided by electron- and hole - doped fullerene systems , which exhibit a variety of behavior , including unconventional metals like cubic csc@xmath6@xcite , superconductors of the a@xmath5c@xmath6 family ( a= k , rb , cs)@xcite , superconducting fet devices@xcite , and insulators , presumably of the mott - jahn - teller type@xcite . among them we can place a@xmath7c@xmath6 @xcite , na@xmath8c@xmath6@xcite and the class of compounds nh@xmath5k@xmath5c@xmath6 , nh@xmath5k@xmath8rbc@xmath6 , nh@xmath5krb@xmath8c@xmath6 , as well as nh@xmath5rb@xmath5c@xmath6@xcite . in these ammoniated compounds ,
insertion of the electronically inert nh@xmath5 molecules acts to expand the c@xmath6 lattice , turning the cubic , metallic and superconducting state of k@xmath5c@xmath6 into an orthorhombic narrow - gap antiferromagnetic insulator @xcite . in this transition ,
the increase in volume per c@xmath6 molecule relative to k@xmath5c@xmath6 , with its probable slight decrease of electron effective bandwidth @xmath9 , is believed to play an important role , as confirmed by the pressure - induced reversion to a fully metallic and superconducting while still orthorhombic .
Please generate the next two sentences of the article | phase @xcite . nonetheless , a possible role of the crystal - structure anisotropy in this mott transition a transition generally believed to occur more readily for reduced orbital degeneracy@xcite , can not be excluded .
it has even been proposed that precisely the splitting of degeneracy@xcite induced by the orthorhombic distortion could be the crucial ingredient driving the transition from the metal and superconductor to the insulator @xcite . |
4,559 | Suppose that you have an abstract for a scientific paper: we extend our previous analysis and consider the interacting holographic ricci dark energy ( irde ) model in non - flat universe .
we study astrophysical constraints on this model using the recent observations including the type ia supernovae ( snia ) , the baryon acoustic oscillation ( bao ) , the cosmic microwave background ( cmb ) anisotropy , and the hubble parameter .
it is shown that the allowed parameter range for the fractional energy density of the curvature is @xmath0 @xmath1 @xmath2 @xmath1 @xmath3 in the presence of the interactions between dark energy and matter . without the interaction , the flat universe is observationally disfavored in this model . .
And you have already written the first three sentences of the full article: the current astrophysical observations of the type ia supernovae ( snia ) @xcite , the cosmic microwave background ( cmb ) @xcite and the large scale structure ( lss ) @xcite have revealed that the expansion of our universe is accelerated @xcite .
this indicates that there exists some unknown energy , called dark energy , to realize the accelerated expansion .
the simplest interpretation of dark energy is the cosmological constant ..
Please generate the next two sentences of the article | however , this model requires an incredible fine - tuning , since the observed cosmological constant is extremely small compared to the fundamental planck scale @xmath4 .
also , this model suffers from the cosmic coincidence problem : why the cosmological constant and matter have comparable energy density today even though their time evolution is so different . among various attempts to solve these problems , |
4,560 | Suppose that you have an abstract for a scientific paper: the newly discovered supernova remnant [email protected] ( rx j0852.00462 ) , along the line of sight to the vela snr , was observed with asca for 120 ks .
we find that the x - ray spectrum is featureless , and well described by a power law , extending to three the class of shell - type snrs dominated by nonthermal x - ray emission . like [email protected] ,
this low - latitude remnant displays discrete regions of enhanced emission along the rim as well as faint nonthermal emission from the interior .
we derive limits on the thermal content of the remnant emission , although the presence of the vela snr compromises our ability to seriously constrain a low temperature component .
limits placed on the amount of sc - k emission are compared with the expected flux based upon the reported @xmath1ti emission from [email protected] .
we also report on an unresolved x - ray source surrounded by diffuse emission near the center of the remnant .
the properties of the source are not well determined , but appear consistent with the interpretation that the source is a neutron star surrounded by a synchrotron nebula .
alternatively , the source may be associated with one of two stars located within the positional error circle , but this appears somewhat unlikely .
= -0.4truein = -.9truein = 7.3truein = 9.4truein = 10001 .
And you have already written the first three sentences of the full article: young supernova remnants ( snrs ) are believed to be the prime accelerators of cosmic rays , at least up to the `` knee '' of the cosmic ray spectrum at energies of @xmath2 tev , beyond which the spectrum steepens . however , the direct evidence for particle acceleration to such energies is scarce .
radio emission from shell - type snrs is the result of synchrotron radiation from shock accelerated electrons , but these electrons have typical energies of order 10 gev .
it is only the recent discoveries of nonthermal x - ray emission from shell - type snrs that have finally provided evidence of particles at energies of 10100 tev ..
Please generate the next two sentences of the article | the x - ray emission from sn 1006 ( koyama et al .
1995 ) and [email protected] ( koyama et al . 1997 , slane et al . 1999 ) is _ predominantly _ nonthermal , while that from cas a , kepler , tycho , and rcw 86 ( allen , gotthelf , & petre 1999 ) is predominantly thermal , but contains a nonthermal component as well . |
4,561 | Suppose that you have an abstract for a scientific paper: the kramers theory of activated processes is generalized for nonequilibrium open one - dimensional systems .
we consider both the internal noise due to thermal bath and the external noise which are stationary , gaussian and are characterized by arbitrary decaying correlation functions .
we stress the role of a nonequilibrium stationary state distribution for this open system which is reminiscent of an equilibrium boltzmann distribution in calculation of rate .
the generalized rate expression we derive here reduces to the specific limiting cases pertaining to the closed and open systems for thermal and non - thermal steady state activation processes . .
And you have already written the first three sentences of the full article: ever since the seminal work of kramers on the diffusion model of chemical reactions was published about half a century ago @xcite , the theory of activated processes has become a central issue in many areas of science @xcite , notably in chemical physics , nonlinear optics and condensed matter physics .
kramers considered a model brownian particle trapped in a one - dimensional well representing the reactant state which is separated by a barrier of finite height from a deeper well signifying the product state .
the particle was supposed to be immersed in a medium such that the medium exerts a frictional force on the particle but at the same time thermally activates it so that the particle may gain enough energy to cross the barrier . over several decades the model and.
Please generate the next two sentences of the article | many of its variants have served as standard paradigms in various problems of physical and chemical kinetics to understand the rate in multidimensional systems in the overdamped and underdamped limits @xcite , effect of anharmonicities @xcite , rate enhancement by parametric fluctuations @xcite , the role of non - gaussian white noise @xcite , role of a relaxing bath @xcite , quantum and semiclassical corrections @xcite to classical rate and related similar aspects .
the vast body of literature has been the subject of several reviews @xcite and monograph @xcite . |
4,562 | Suppose that you have an abstract for a scientific paper: we consider string junctions with endpoints on a set of branes of iib string theory defining an @xmath0-type gauge lie algebra .
we show how to characterize uniquely equivalence classes of junctions related by string / brane crossing through invariant charges that count the effective number of prongs ending on each brane .
each equivalence class defines a point on a lattice of junctions .
we define a metric on this lattice arising from the intersection pairing of junctions , and use self - intersection to identify junctions in the adjoint and fundamental representations of all @xmath0 algebras .
this information suffices to determine the relation between junction lattices and the lie - algebra weight lattices .
arbitrary representations are built by allowing junctions with asymptotic @xmath1 charges , on which the group of conjugacy classes of representations is represented additively .
one can view the @xmath1 asymptotic charges as dynkin labels associated to two new fundamental weight vectors .
8.5 in 6.5 in -.35 in = cmss10 = cmssq8 = cmssbx10 = cmssbx10 scaled 1200 addtoresetequationsection boxedeps.tex 5_5 l # 1 # 1 | # 1| # 1 # 1#1 # 1#2#1 | # 2 # 1#2(#1 # 2 ) _ 2zsl(2 , ) # 1#2#1#2 _ 0.8 cm oliver dewolfe and barton zwiebach 0.2 cm _ center for theoretical physics , + laboratory for nuclear science , + department of physics + massachusetts institute of technology + cambridge , massachusetts 02139 , u.s.a . _ .
And you have already written the first three sentences of the full article: in the modern viewpoint on gauge symmetry enhancement in open string theory , the gauge vectors associated to a @xmath2 gauge algebra are seen to arise from open strings beginning and ending on a collection of @xmath3 dirichlet branes ( see @xcite ) . given the utility and simplicity of brane pictures for gauge theory it is of interest to understand the brane picture of other gauge algebras .
a natural laboratory for this problem is iib superstrings compactified on a two - sphere in the presence of several 7-branes appearing as points on this sphere and extending along the other spatial dimensions . in this background
both strings and seven branes carry @xmath1 labels . here.
Please generate the next two sentences of the article | @xmath4 and @xmath5 are relatively prime integers denoting for the case of a string the charges under the ns - ns and rr antisymmetric tensors respectively .
a @xmath6 $ ] seven - brane is a seven - brane where a @xmath7 string can end . |
4,563 | Suppose that you have an abstract for a scientific paper: we analyze the x - ray spectrum of the quasar pg1211 + 143 observed with the ccd and grating spectrometers on board _ xmm - newton_. using an ion by ion fitting model we find an outflow component of about 3000 ^-1 kms@xmath0that includes absorption lines of k - shell and l - shell ions of the astrophysically abundant elements .
we also identify and include in our model broad ( fwhm = 6000 ^ -1 kms@xmath0 ) emission lines from h - like ions of c , n , o , and ne , and he - like ions of o , ne , and mg .
the outflow velocity we find is an alternative interpretation of the data and is in contrast with the ultra high velocity of @xmath1 24000 ^-1 kms@xmath0 reported previously for this object .
nevertheless , we can not completely rule out the presence of a high velocity component due to the poor signal - to - noise ratio of the data . .
And you have already written the first three sentences of the full article: the phenomenon of outflowing mass from the cores of active galactic nuclei ( agns ) has been well established by now .
typical velocities of a few hundreds to a few thousands ^-1
kms@xmath0 have been measured in numerous objects ( crenshaw et al . 2003 and references therein ) ..
Please generate the next two sentences of the article | recent studies of the x - ray spectra of certain quasars have led to claims of much higher outflow velocities reaching a significant fraction of the speed of light . in apm08279
+ 5255 , chartas et al . |
4,564 | Suppose that you have an abstract for a scientific paper: we model the dynamics of social structure by a simple interacting particle system .
the social standing of an individual agent is represented by an integer - valued fitness that changes via two offsetting processes .
when two agents interact one advances : the fitter with probability @xmath0 and the less fit with probability @xmath1 .
the fitness of an agent may also decline with rate @xmath2 . from a scaling analysis of the underlying master equations for the fitness distribution of the population , we find four distinct social structures as a function of the governing parameters @xmath0 and @xmath2 .
these include : ( i ) a static lower - class society where all agents have finite fitness ; ( ii ) an upwardly - mobile middle - class society ; ( iii ) a hierarchical society where a finite fraction of the population belongs to a middle class and a complementary fraction to the lower class ; ( iv ) an egalitarian society where all agents are upwardly mobile and have nearly the same fitness .
we determine the basic features of the fitness distributions in these four phases . .
And you have already written the first three sentences of the full article: the emergence of class structure in society is a ubiquitous phenomenon in the biological and the social sciences @xcite .
social hierarchies have been widely observed in animal populations including insects @xcite , mammals @xcite , and primates @xcite , as well as human communities @xcite . the possibility of quantitative modeling of social phenomena using concepts and techniques borrowed from the physical sciences is rapidly gaining appreciation .
examples of such modeling include the wealth distribution @xcite , opinion dynamics @xcite , and rumor propagation @xcite ..
Please generate the next two sentences of the article | such approaches typically draw analogies between individual agents in the social system and particles in a corresponding physical system and then identifying macroscopically observed phenomena with microscopic agent - agent interactions @xcite . in this spirit , we seek to tie the emergence of social structures to specific interactions between agents within a general version of the recently - introduced advancement - decline process @xcite . in our model ,
the social standing of each agent is characterized by a single number , its fitness . |
4,565 | Suppose that you have an abstract for a scientific paper: in this article , i briefly review the status of infrared effects which occur when using inflationary models to calculate initial conditions for a subsequent hot , dense plasma phase .
three types of divergence have been identified in the literature : secular , `` time - dependent '' logarithms , which grow with time spent outside the horizon ; `` box - cutoff '' logarithms , which encode a dependence on the infrared cutoff when calculating in a finite - size box ; and `` quantum '' logarithms , which depend on the ratio of a scale characterizing new physics to the scale of whatever process is under consideration , and whose interpretation is the same as conventional field theory .
i review the calculations in which these divergences appear , and discuss the methods which have been developed to deal with them
. diags .
And you have already written the first three sentences of the full article: looking out at the universe from the vantage point of earth , we see a small fluctuation @xmath0 in the temperature of the cosmic microwave background radiation ( cmb ) . over the last decade , advances in observational astronomy have allowed us to commence a detailed study of @xmath0 s statistical properties .
we aim to compare these properties with those of small fluctuations which , according to our present ideas , are expected to have existed in the very early universe .
these fluctuations evolve in a hot , dense plasma of tightly coupled baryons and photons ..
Please generate the next two sentences of the article | if we suppose the plasma era was preceded by an epoch of primordial inflation , then initial conditions for these fluctuations can be calculated from the parameters of the inflationary model . the variance predicted by this approach
was computed in a now - classic series of early papers @xcite , and later extended to the skewness @xcite and kurtosis @xcite . with sufficiently precise experimental data in hand |
4,566 | Suppose that you have an abstract for a scientific paper: qcd - like theories possess a positively definite fermion determinant at finite baryon chemical potential @xmath0 and the lattice simulation can be successfully performed .
while the chiral perturbation theories are sufficient to describe the bose condensate at low density , to describe the crossover from bose - einstein condensation ( bec ) to bcs superfluidity at moderate density we should use some fermionic effective model of qcd , such as the nambu jona - lasinio model . in this paper , using two - color two - flavor qcd as an example , we examine how the nambu jona - lasinio model describes the weakly interacting bose condensate at low density and the bec - bcs crossover at moderate density .
near the quantum phase transition point @xmath1 ( @xmath2 is the mass of pion / diquark multiplet ) , the ginzburg - landau free energy at the mean - field level can be reduced to the gross - pitaevskii free energy describing a weakly repulsive bose condensate with a diquark - diquark scattering length identical to that predicted by the chiral perturbation theories .
the goldstone mode recovers the bogoliubov excitation in weakly interacting bose condensates .
the results of in - medium chiral and diquark condensates predicted by chiral perturbation theories are analytically recovered .
the bec - bcs crossover and meson mott transition at moderate baryon chemical potential as well as the beyond - mean - field corrections are studied .
part of our results can also be applied to real qcd at finite baryon or isospin chemical potential . .
And you have already written the first three sentences of the full article: a good understanding of quantum chromodynamics ( qcd ) at finite temperature and baryon density is crucial for us to understand a wide range of physical phenomena .
for instance , to understand the evolution of the universe in the first few seconds , one needs the knowledge of qcd phase transition at temperature @xmath3mev and very small baryon density . on the other hand ,
understanding the physics of neutron stars requires the knowledge of qcd at high baryon density and very low temperature @xcite ..
Please generate the next two sentences of the article | lattice simulation of qcd at finite temperature has been successfully performed in the past few decades ; however , no successful lattice simulation at high baryon density has been done due to the sign problem @xcite : the fermion determinant is not positively definite in presence of a nonzero baryon chemical potential @xmath0 .
we thus look for some special cases which have a positively definite fermion determinant . |
4,567 | Suppose that you have an abstract for a scientific paper: a model of a carbon - oxygen ( c o ) presupernova core with an initial mass @xmath0 , an initial carbon mass fraction @xmath1 , and with an average mass growth - rate @xmath2 due to accretion in a binary system was evolved from initial density @xmath3 , and temperature @xmath4k through convective core formation and its subsequent expansion to the carbon runaway at the center . the only thermonuclear reaction contained in the equations of evolution and runaway was the carbon burning reaction @xmath5c@xmath6c with an energy release corresponding to the full transition of carbon and oxygen ( with the same rate as carbon ) into @xmath7ni . as a parameter we take @xmath8
a ratio of a mixing length to the size of the convective zone . in spite of the crude assumptions , we obtained a pattern of the runaway acceptable for the supernova theory with the strong dependence of its duration on @xmath8 . in the variants with large enough values of @xmath9 and
@xmath10 the fuel combustion occurred from the very beginning as a prompt detonation . in the range of @xmath11
the burning started as a deflagration with excitation of stellar pulsations with growing amplitude . eventually , the detonation set in , which was activated near the surface layers of the presupernova ( with @xmath12 ) and penetrated into the star down to the deflagration front .
excitation of model pulsations and formation of a detonation front are described in detail for the variant with @xmath13 .
_ keywords : _ supernovae and supernova remnants ; plasma astrophysics ; hydrodynamics and shock waves ; detonation and deflagration . .
And you have already written the first three sentences of the full article: evolution of a degenerate c o stellar core with a mass close to the chandrasekhar limit ( @xmath14 for a carbon white dwarf , see bisnovatyi - kogan , 1989 ) leads to the development of thermal instability and to the explosion .
the critical density @xmath15 for the beginning of the explosion may vary from @xmath16 to @xmath17 .
it increases with reduction of @xmath18 the core mass growth - rate which for a single asymptotic giant branch ( agb ) star is defined by the paczyski uus relation ( paczyski , 1970 ) @xmath19 and can take values from @xmath20 to @xmath21 in an accreting white dwarf ( iben , 1982 ; hachisu et al . , 1996 ) . in the present paper.
Please generate the next two sentences of the article | we assume @xmath22 which can be appropriate both for a single agb - star and for a component of a binary system .
the explosion calculations , some of which accounted for convection , were carried by various authors ( arnett , 1969 ; ivanova et al . , 1974 ; nomoto et al . , 1976 |
4,568 | Suppose that you have an abstract for a scientific paper: we analyze the properties of the energy landscape of _ finite - size _ fully connected @xmath0-spin - like models whose high temperature phase is described , in the thermodynamic limit , by the schematic mode coupling theory of super - cooled liquids .
we show that _ finite - size _ fully connected @xmath0-spin - like models , where activated processes are possible , do exhibit properties typical of real super - cooled liquid when both are near the critical glass transition .
our results support the conclusion that fully - connected @xmath0-spin - like models are the natural statistical mechanical models for studying the glass transition in super - cooled liquids . and glass transition , spin - glass , random models pacs : 64.70.pf , 75.10.nr , 61.20.gy , 82.20.wt .
And you have already written the first three sentences of the full article: in recent years a significant effort has been devoted to the understanding of glass - forming systems .
recent theoretical and numerical results clearly show that the slowing down of the dynamics near the glass transition is strongly connected to the potential energy landscape geometry .
the trajectory of the representative point in the configuration space can be viewed as a path in a multidimensional potential energy surface @xcite ..
Please generate the next two sentences of the article | the dynamics is therefore strongly influenced by the topography of the potential energy landscape : local minima , barriers heights , basins of attraction an other topological properties all influence the dynamics .
the potential energy surface of a super - cooled liquid contains a large number of local minima , called _ inherent structures _ ( is ) by stillinger @xcite . all states that under local energy minimization will flow into |
4,569 | Suppose that you have an abstract for a scientific paper: a new method for solving numerically stochastic partial differential equations ( spdes ) with multiple scales is presented .
the method combines a spectral method with the heterogeneous multiscale method ( hmm ) presented in [ w. e , d. liu , and e. vanden - eijnden , comm .
pure appl .
math .
, 58(11):15441585 , 2005 ] . the class of problems that we consider are spdes with quadratic nonlinearities that were studied in [ d. blmker , m. hairer , and g. a. pavliotis , nonlinearity , 20(7):17211744 , 2007 . ] for such spdes an amplitude equation which describes the effective dynamics at long time scales can be rigorously derived for both advective and diffusive time scales .
our method , based on micro and macro solvers , allows to capture numerically the amplitude equation accurately at a cost independent of the small scales in the problem .
numerical experiments illustrate the behavior of the proposed method .
stochastic partial differential equations ; multiscale methods ; averaging ; homogenization ; heterogeneous multiscale method ( hmm ) .
And you have already written the first three sentences of the full article: [ sec : intro ] many interesting phenomena in the physical sciences and in applications are characterized by their high dimensionality and the presence of many different spatial and temporal scales .
standard examples include atmosphere and ocean sciences @xcite , molecular dynamics @xcite and materials science @xcite .
the mathematical description of phenomena of this type quite often leads to infinite dimensional multiscale systems that are described by nonlinear evolution partial differential equations ( pdes ) with multiple scales ..
Please generate the next two sentences of the article | often physical systems are also subject to noise .
this noise might be either due to thermal fluctuations @xcite , noise in some control parameter @xcite , coarse - graining of a high - dimensional deterministic system with random initial conditions @xcite , or the stochastic parameterization of small scales @xcite . |
4,570 | Suppose that you have an abstract for a scientific paper: we investigate a scheduling scheme incorporating network coding and channel varying information for the two - way relay networks .
our scheduler aims at minimizing the time span needed to send all the data of each source of the network .
we consider three channel models , time invariant channels , time varying channels with finite states and time varying rayleigh fading channels .
we formulate the problem into a manageable optimization problem , and get a closed form scheduler under time invariant channels and time varying channel with finite channel states . for rayleigh fading channels , we focus on the relay node operation and propose heuristic power allocation algorithm resemblant to water filling algorithm . by simulations , we find that even if the channel fluctuates randomly , the average time span is minimized when the relay node transmits / schedules network coded data as much as possible . network coding , scheduling , time span , two - way relay networks . .
And you have already written the first three sentences of the full article: network coding attracted the attention in wireless networks @xcite .
the network coding benefit is easily represented by reducing the number of transmissions . for example , in two - way relay networks @xcite of figure [ f : twoway ] , the traditional method requires four slots to exchange data , whereas the network coded relaying requires three slots @xcite . in @xcite ,
moreover , two - slot transmission strategy is studied . in the example.
Please generate the next two sentences of the article | , the relay node should have data from both source nodes to execute network coding .
this means the source nodes must transmit their data before the relay node does . |
4,571 | Suppose that you have an abstract for a scientific paper: we present a new method to extract parton distribution functions from high energy experimental data based on a specific type of neural networks , the self - organizing maps .
we illustrate the features of our new procedure that are particularly useful for an anaysis directed at extracting generalized parton distributions from data .
we show quantitative results of our initial analysis of the parton distribution functions from inclusive deep inelastic scattering . .
And you have already written the first three sentences of the full article: high energy processes can be described within quantum chromodynamics ( qcd ) through its factorization properties .
these allow us to write the cross sections by separating the hard part , which is the well defined interaction of a quark with _
e.g. _ a virtual photon , from the soft part , described in terms of parton distributions functions ( pdfs ) ..
Please generate the next two sentences of the article | the latter can not be calculated from first principles .
information about the pdfs can only be obtained directly from experiment . |
4,572 | Suppose that you have an abstract for a scientific paper: we consider the classical @xmath0-symmetric models confined in a @xmath1-dimensional slab - like geometry and subject to periodic boundary conditions . applying the one - particle - irreducible variant of functional renormalization group ( rg ) we compute the critical casimir forces acting between the slab boundaries .
the applied truncation of the exact functional rg flow equation retains interaction vertices of arbitrary order .
we evaluate the critical casimir amplitudes @xmath2 for continuously varying dimensionality between two and three and @xmath3 .
our findings are in very good agreement with exact results for @xmath4 and @xmath5 . for @xmath6
our results are closer to monte carlo predictions than earlier field - theoretic rg calculations .
inclusion of the wave function renormalization and the corresponding anomalous dimension in the calculation has negligible impact on the computed casimir forces . .
And you have already written the first three sentences of the full article: the concept of casimir forces,@xcite i.e. long - ranged effective interactions between macroscopic bodies immersed in strongly fluctuating media , is nowadays recognized in plethora of systems ranging from biology to cosmology .
on one hand their prominent importance stems from providing possibilities of testing theories of fundamental interactions,@xcite on the other they are invoked to explain important mechanisms underlying physical phenomena in organic matter@xcite and as a control tool for nanodevices.@xcite the more conventional and well - studied ( also experimentally ) examples of casimir forces in condensed matter include fluid mixtures@xcite and helium.@xcite the essence of the phenomenology underlying the casimir forces is the presence of soft fluctuations occurring within a medium , whose spectrum of excitations becomes constrained by the boundary conditions imposed by the confining walls or by macroscopic objects immersed therein . as a result ,
the free energy acquires a contribution depending on the separation @xmath7 between the walls ( or the objects ) and the system finds it favorable to either increase or decrease this distance ..
Please generate the next two sentences of the article | a prominent characteristic of casimir forces is the universality of its asymptotic behavior ( including the amplitude ) for @xmath8 and @xmath9 , where @xmath10 is a system - specific microscopic lengthscale and @xmath11 denotes the ( bulk ) correlation length for the medium fluctuations .
if the system features spontaneously broken continuous symmetry , one should additionally distinguish the transverse and longitudinal bulk correlation lengths . |
4,573 | Suppose that you have an abstract for a scientific paper: we study the effect of electron - vibron interactions on the inelastic transport properties of single - molecule nanojunctions .
we use the non - equilibrium green s functions technique and a model hamiltonian to calculate the effects of second - order diagrams ( double - exchange dx and dressed - phonon dph diagrams ) on the electron - vibration interaction and consider their effects across the full range of parameter space .
the dx diagram , corresponding to a vertex correction , introduces an effective dynamical renormalization of the electron - vibron coupling in both the purely inelastic and the inelastic - resonant features of the iets .
the purely inelastic features correspond to an applied bias around the energy of a vibron , while the inelastic - resonant features correspond to peaks ( resonance ) in the conductance .
the dph diagram affects only the inelastic resonant features .
we also discuss the circumstances in which the second - order diagrams may be approximated in the study of more complex model systems . .
And you have already written the first three sentences of the full article: junctions consisting of a single organic molecule between two metallic leads hold great promise for future nanoscale devices , where their potential applications include switches , transistors , and sensors .
experimentally , it has proved difficult to control their production in an atomistic manner , and so theoretical studies are crucial for a full understanding of their behaviour .
it is known that inelastic effects play an important role in the behaviour of such devices @xcite , but as yet we lack a full understanding of the processes at play that will lead to a complete interpretation of experimental results . in this paper.
Please generate the next two sentences of the article | , we use a model - system nanojunction including electron - vibration coupling @xcite in order to determine , by investigating the whole parameter space , what level of diagrammatic expansion is appropriate to describe the electron - vibration interaction in such junctions . we cover the entire parameter space , thus accounting for all the physical analogues to our model .
the parameters we can vary correspond to the lead - molecule - lead coupling , the electron - vibron coupling strength , and the resonance of the electronic level with the leads electronic states in general , an organic molecule - based nanojunction is unlikely to have its homo or lumo levels in alignment with the equilibrium fermi level of the leads , and so such a nanojunction will be dominated by what we term the off - resonant regime with strong tunneling at low bias . |
4,574 | Suppose that you have an abstract for a scientific paper: the three - loop effective potential of the massless @xmath0 @xmath1 theory is calculated analytically using techniques of dimensional regularization .
we see a complete agreement between our result and jackiw s result which was obtained only up to two - loop order using a different regularization ( cutoff regularization ) method , but the same renormalization conditions . for an easy check of the mutual cancellation of all the dangerous pole terms in each loop order , we give the @xmath2-expanded loop integrals in full detail .
dratex.sty ~ ps . .
And you have already written the first three sentences of the full article: the effective potential plays a crucial role in determining the nature of the vacuum in a weakly coupled field theory , as was emphasized in the classic paper of coleman and weinberg @xcite .
calculation of this object by summing infinite series of feynman diagrams at zero momentum is an onerous task , especially when several interactions are present which complicate the combinatorial factors that multiply each diagram .
jackiw has succeeded in representing each loop order containing an infinite set of conventional feynman diagrams by finite number of diagrams using his algebraic method which can be formally extended to the arbitrary higher loop order @xcite ..
Please generate the next two sentences of the article | self - interacting scalar field theory of @xmath1 model is one of the best analyzed field theories .
various renormalization group functions of @xmath0 @xmath1 theory are now available up to the five - loop order @xcite . however , the three - loop effective potential of the same theory is less progressive . |
4,575 | Suppose that you have an abstract for a scientific paper: we perform advanced radiation leakage microscopy of routing dielectric - loaded plasmonic waveguiding structures . by direct plane imaging and momentum - space spectroscopy
, we analyze the energy transfer between coupled waveguides as a function of gap distance and reveal the momentum distribution of curved geometries .
specifically , we observed a clear degeneracy lift of the effective indices for strongly interacting waveguides in agreement with coupled - mode theory .
we use momentum - space representations to discuss the effect of curvature on dielectric - loaded waveguides .
the experimental images are successfully reproduced by a numerical and an analytical model of the mode propagating in a curved plasmonic waveguide . .
And you have already written the first three sentences of the full article: confinement and propagation of surface plasmons in a metal circuitry have received considerable interest for their capability to transport data with a large bandwidth in compact structures and devices . among the different geometries capable of routing the flow of surface plasmon , dielectric - loaded surface plasmon
polariton waveguides ( dlsppws ) @xcite have recently emerged as a potential plasmonic architecture that can be integrated seamlessly with current silicon - on - insulator ( soi ) photonic circuits @xcite and can sustain transfer of information at high date rates @xcite .
a dlsppw is made of a rectangular dielectric rib deposited on a metal film or strip @xcite ..
Please generate the next two sentences of the article | the surface plasmon is confined in the dielectric layer and typical cross - sections required for an optimum confinement of the mode compare well with state - of - the - art soi waveguides operating in the telecom bands . despite dramatically higher losses ,
the advantage of such plasmonic platform is that the optical index of dielectric material used to confined the mode can be externally controlled to realize active dlsppw - based devices @xcite . |
4,576 | Suppose that you have an abstract for a scientific paper: with the help of the mellin - barnes transform , we show how to simultaneously resum the expansion of a heavy - quark correlator around @xmath0 ( low - energy ) , @xmath1 ( threshold , where @xmath2 is the quark mass ) and @xmath3 ( high - energy ) in a systematic way .
we exemplify the method for the perturbative vector correlator at @xmath4 and @xmath5 .
we show that the coefficients , @xmath6 , of the taylor expansion of the vacuum polarization function in terms of the conformal variable @xmath7 admit , for large @xmath8 , an expansion in powers of @xmath9 ( up to logarithms of @xmath8 ) that we can calculate exactly .
this large-@xmath8 expansion has a sign - alternating component given by the logarithms of the ope , and a fixed - sign component given by the logarithms of the threshold expansion in the external momentum @xmath10 .
* resummation of threshold , low- and high - energy + expansions for heavy - quark correlators * + * david greynat@xmath11 * and * santiago peris@xmath12 * + @xmath11ifae , @xmath13grup de fsica terica , dept . de fisica + univ .
autnoma de barcelona , 08193 barcelona , spain . + .
And you have already written the first three sentences of the full article: two - point correlators of heavy quarks are very useful objects for extracting parameters of qcd such as , e.g. , the quark masses and the strong coupling constant @xmath14 , both from experiment@xcite and also from the lattice@xcite . however , even our perturbative knowledge of these functions is quite limited due to the complexity of the required diagrammatic calculation .
for instance , in the case of the vector vacuum polarization function , only at @xmath15 and @xmath16 is the analytic result fully known @xcite . at @xmath17 ,
state - of - the - art techniques produce partial answers for this function only in the form of local expansions around three particular values of the external momentum , to wit @xmath0 , @xmath3 and @xmath18 where @xmath2 is the heavy - quark mass ..
Please generate the next two sentences of the article | these correspond to the so - called low - energy expansion , the operator product expansion and the threshold expansion of the correlator .
a phenomenal effort has been devoted to the calculation of an ever - increasing number of coefficients in all of these expansions . |
4,577 | Suppose that you have an abstract for a scientific paper: we model quantum hall skyrmions in graphene monolayer at quarter filling by a theory of @xmath0 fields and study the energy minimizing skyrmions in presence of valley pseudospin anisotropy and zeeman coupling .
we present a diagram of all types of skyrmions in a wide range of the anisotropy parameters . for each type of skyrmion
, we visualize it on three bloch spheres , and present the profiles of its texture on the graphene honeycomb lattice , thus providing references for the stm / sts imaging of spin - pseudospin textures in graphene monolayer in quantum hall regime .
besides the spin and pseudospin skyrmions for the corresponding degrees of freedom of an electron in the @xmath1 landau level , we discuss two unusual types the `` entanglement skyrmion '' whose texture lies in the space of the entanglement of spin and pseudospin , as well as the `` deflated pseudospin skyrmion '' with partial entanglement . for all skyrmion types ,
we study the dependence of the energy and the size of a skyrmion on the anisotropy parameters and perpendicular magnetic field . we also propose three ways to modify the anisotropy energy , namely the sample tilting , the substrate anisotropy and the valley pseudospin analogue of zeeman coupling . .
And you have already written the first three sentences of the full article: a skyrmion , first introduced in high - energy physics in the description of baryons,@xcite is a topologically non - trivial configuration of a continuous field @xmath2 , which is localized , in the sense that its gradient @xmath3 is significant only in a finite spatial region @xmath4 . far away from @xmath4 , the field @xmath2
approaches a uniform configuration , which is conveniently described by a boundary condition at spatial infinity.@xcite the euclidean action @xmath5 $ ] usually has the form of non - linear sigma model ( nlsm ) , with the lower bounds of energy being guaranteed by the bogomolnyi prasad sommerfield inequality .
@xcite such lower bound is proportional to @xmath6 the absolute value of an integer `` topological charge '' @xmath7 , which classifies the field @xmath2 as a continuous mapping . in the work of skyrme , @xcite @xmath2 maps the ( compactified ) 3 + 1 dimensional space - time to the manifold of lie group @xmath8 ( which is isomorphic to @xmath9 , the 3-sphere ) , and the third homotopy group @xmath10 provides the topological charge @xmath7 , which was identified as particle number in that work ..
Please generate the next two sentences of the article | after its introduction in high - energy physics , skyrmion physics regained interest in the context of condensed - matter physics as a topological object in a two - dimensional ferromagnetic state .
they have been discussed in quantum hall systems,@xcite and in chiral magnets@xcite and magnetic thin films.@xcite while skyrmions have been experimentally viewed in scanning - tunnelling microscopy and spectroscopy ( stm / sts ) in the latter two systems,@xcite skyrmions in quantum hall systems have mainly been identified through their magnetic properties in nuclear - magnetic - resonance experiments,@xcite and a spectroscopic identification is yet outstanding . |
4,578 | Suppose that you have an abstract for a scientific paper: we present radio imaging observations of the 1998 outburst of the peculiar emission line star , taken @xmath01 , 4 , 75 , 82 , 93 , 163 , and 306 days after the beginning of the 31.64 march 1998 x - ray flare .
the first two epochs show a resolved but compact ( no larger than 12 milliarcseconds ) radio source which becomes optically thin at frequencies higher than 5ghz .
the spectrum and brightness temperatures are consistent with synchrotron self - absorption , although free - free absorption may also play a role .
the later images show a large ( 120 - 350milliarcseconds ) oval - shaped or double ring remnant .
the radio spectrum combined with the high brightness temperature indicates that the emission is synchrotron , while the morphology suggests that this is powered by a decelerating shock moving through dense circumstellar material produced by a strong stellar wind .
the radio images of are equally well fit by an expanding ellipsoid or two expanding rings ; the former gives @xmath1 , with @xmath2 the major axis in mas and @xmath3 the modified julian date ( mjd ) .
the corresponding expansion speed in the plane of the sky was @xmath4 over the first few days ( for an assumed distance of 5kpc ) , slowing by a factor @xmath5 by the time of the last observation almost a year later .
the radio emission from all other x - ray binary transients has either been unresolved , or taken the form of highly collimated relativistic jets .
we suggest that represents a rare case where these jets were smothered early on by the unusually dense circumstellar medium . in this model
is the analogue to extragalactic supernovae formed by the collapsar mechanism , while the more usual x - ray binaries with relativistic jets are analogous to the jets which escape those supernovae to form a subset of @xmath6-ray bursts . .
And you have already written the first three sentences of the full article: xte j0421 + 560 was discovered by the all - sky monitor ( asm ) on the rossi x - ray timing explorer ( rxte ) on 31.64 march 1998 @xcite as the first bright x - ray transient in several years , reaching almost 2 crabs within a day of the first detection .
corresponding radio emission was detected soon after ( 1.9 april ; @xcite ) .
optical observations @xcite identified the radio and x - ray transient as the star , based on positional coincidence with the radio emission , and a concurrent optical outburst ..
Please generate the next two sentences of the article | it was also detected by the burst and transient source experiment in the low energy gamma
rays , reaching a flux of 1.6mcrab in the 2040 kev band @xcite . is a peculiar bright emission - line star with unusually strong fe ii lines @xcite , indicating a very hot star or stellar shell . |
4,579 | Suppose that you have an abstract for a scientific paper: we provide an alternative method for analysis of multifractal properties of time series .
the new approach takes into account the behavior of the whole multifractal profile of the generalized hurst exponent @xmath0 for all moment orders @xmath1 , not limited only to the edge values of @xmath0 describing in mfdfa scaling properties of smallest and largest fluctuations in signal .
the meaning of this new measure is clarified and its properties are investigated for synthetic multifractal data as well as for real signals from stock markets . we show that the proposed new measure is free of problems one can meet in real nonstationary signals , while searching their multifractal signatures .
@xmath2 * keywords * : multifractality , spurious multifractality , finite size effects , multifractal detrended analysis , multifractal bias , scaling , time series analysis , new multifractal measure , generalized hurst exponent + * pacs : * 05.45.tp , 89.75.da , 05.40.-a , 89.65.gh,89.75.-k + .
And you have already written the first three sentences of the full article: the multifractal detrended fluctuation analysis ( mfdfa ) @xcite became in last ten years the major technique used for studying the multifractal properties in complex systems and in time series .
more then 500 papers discusses mfdfa issues in variety of problems related with complexity ( see , e.g. , @xcite@xcite ) . the central role in mfdfa
is played by the @xmath1-th moment of fluctuation function ( @xmath3 ) defined as @xcite @xmath4^{q/2}\right\}^{1/q}\ ] ] for @xmath5 , and @xmath6\right\}\ ] ] for @xmath7 , where @xmath8 and @xmath9 ( @xmath10 ) are data in series , @xmath11 is the size of window box in which detrending is performed , while @xmath12 is the polynomial trend subtracted for @xmath13-th data in @xmath14-th window box ( @xmath15 ) ..
Please generate the next two sentences of the article | the observed scaling law @xmath16 is crucial within mfdfa to estimate the multifractal properties of a signal given by the profile of generalized hurst exponents @xmath0 .
the strength of multifractality present in data is usually studied as a spread @xmath17 @xmath18 of some edge values of generalized hurst exponent @xmath19 calculated at the fixed negative ( @xmath20 ) and positive ( @xmath21 ) moments respectively ( @xmath22 ) . in the case of stationary series |
4,580 | Suppose that you have an abstract for a scientific paper: the location of hii regions , which indicates the locus of present star formation in galaxies , is analyzed for a large collection of 110 irregular galaxies ( irr ) imaged in h@xmath0 and nearby continuum .
the analysis is primarily by visual inspection , although a two - dimensional quantitative measure is also employed .
the two different analyses yield essentially identical results .
hii regions appear preferentially at the edges of the light distribution , predominantly on one side of the galaxy , contrary to what is expected from stochastic self - propagating star formation scenarios .
this peculiar distribution of star forming regions can not be explained by a scenario of star formation triggered by an interaction with extragalactic gas , or by a strong one - armed spiral pattern .
# 1#2#3#4#5#6#7 to#2 ' '' '' .
And you have already written the first three sentences of the full article: the star formation ( sf ) is a fundamental process in the evolution of galaxies and is far from being well understood .
the sf is usually characterized by the initial mass function ( imf ) and the total sf rate ( sfr ) , which depends on many factors such as the density of the interstellar gas , its morphology , its metallicity , _ etc . _
generally , four major factors drive star formation in galaxies : large scale gravitational instabilities , cloud compression by density waves , compression in a rotating galactic disk due to shear forces , and random gas cloud collisions . in galaxies with previous stellar generations.
Please generate the next two sentences of the article | additional sf triggers exist , such as shock waves from stellar winds and supernova explosions . in dense environments , such as clusters of galaxies and compact groups , tidal interactions , collisions with other galaxies ,
ism stripping , and cooling flow accretion probably play some role in triggering the sf process . |
4,581 | Suppose that you have an abstract for a scientific paper: electrical impedance tomography ( eit ) provides functional images of an electrical conductivity distribution inside the human body . since the 1980s
, many potential clinical applications have arisen using inexpensive portable eit devices .
eit acquires multiple trans - impedance measurements across the body from an array of surface electrodes around a chosen imaging slice .
the conductivity image reconstruction from the measured data is a fundamentally ill - posed inverse problem notoriously vulnerable to measurement noise and artifacts .
most available methods invert the ill - conditioned sensitivity or jacobian matrix using a regularized least - squares data - fitting technique .
their performances rely on the regularization parameter , which controls the trade - off between fidelity and robustness . for clinical applications of eit ,
it would be desirable to develop a method achieving consistent performance over various uncertain data , regardless of the choice of the regularization parameter . based on the analysis of the structure of the jacobian matrix , we propose a fidelity - embedded regularization ( fer ) method and a motion artifact removal filter . incorporating the jacobian matrix in the regularization process , the new fer method with the motion artifact removal filter offers stable reconstructions of high - fidelity images from noisy data by taking a very large regularization parameter value .
the proposed method showed practical merits in experimental studies of chest eit imaging . .
And you have already written the first three sentences of the full article: eit is a non - invasive real - time functional imaging modality for the continuous monitoring of physiological functions such as lung ventilation and perfusion .
the image contrast represents the time change of the electrical conductivity distribution inside the human body . using an array of surface electrodes around a chosen imaging slice ,
the imaging device probes the internal conductivity distribution by injecting electrical currents at tens or hundreds of khz ..
Please generate the next two sentences of the article | the injected currents ( at safe levels ) produce distributions of electric potentials that are non - invasively measured from the attached surface electrodes .
a portable eit system can provide functional images with an excellent temporal resolution of tens of frames per second . |
4,582 | Suppose that you have an abstract for a scientific paper: the role of rescattering due to the final state interaction ( fsi ) and the influence of the finite formation time ( fft ) on the inclusive @xmath0 and exclusive @xmath1 electro - disintegration of the deuteron are studied in the cumulative kinematical region @xmath2 and moderate values of the 4-momentum transfer @xmath3 ( gev / c)@xmath4 .
the spins are averaged out .
it is found that in the inclusive process the relative magnitude of rescattering steadily grows with @xmath5 and that at @xmath6 it has the same order as the plane wave impulse approximation ( pwia ) contribution , with the finite formation time effects decreasing the rescattering contribution by @xmath7% . in the exclusive process , with increasing momentum transfer
, fft substantially reduces the effects from fsi , although the latter are still appreciable in the region of momentum transfer investigated . .
And you have already written the first three sentences of the full article: high - energy electro - disintegration of the deuteron is a powerful tool to investigate , first , how and when at larger energies and momentum transfers the description in terms of hadrons ( nucleons and mesons ) transforms into the one in terms of quarks and gluons and , second , the colour transparency ( ct ) effects predicted by qcd . in terms of relevant feynman diagrams , one expects that whereas at comparatively low energies virtual nucleons and mesons with standard propagators can be used , at large enough virtualities such a description gradually becomes invalid . to clearly see this phenomenon one has to be able to reach high enough virtualities in the process , which can be achieved by choosing the kinematics forbidden for free ( on - mass - shell ) nucleons ,
i.e. the so - called _ cumulative _ kinematics , which corresponds to values of the bjorken scaling variable larger than one ( note that the importance of studying the @xmath5-dependence of ct was first stressed in ref .
@xcite ) . in the pwia.
Please generate the next two sentences of the article | the cross - sections are directly related to the behaviour of the deuteron wave function .
however such a direct relation is broken by fsi , which naively are expected to be large in the cumulative region ; it is here that ct effects are to be taken into account . |
4,583 | Suppose that you have an abstract for a scientific paper: we present an analysis of `` bistability '' in gas - phase chemical models of dark interstellar clouds .
we identify the chemical mechanisms that allow high- and low - ionization solutions to the chemical rate - equations to coexist .
we derive simple analytic scaling relations for the gas densities and ionization rates for which the chemistry becomes bistable .
we explain why bistability is sensitive to the h@xmath0 dissociative recombination rate coefficient , and why it is damped by gas - grain neutralization . .
And you have already written the first three sentences of the full article: in this paper we reexamine and analyze the phenomenon of `` bistability '' that occurs in chemical models of dark interstellar clouds .
bistability was first discussed by le bourlot et al .
( 1993 ) , who found that multiple solutions to the chemical rate - equations sometimes appear in numerical computations of the gas - phase abundances of atomic and molecular species for steady - state dark cloud conditions ..
Please generate the next two sentences of the article | when bistability occurs , three sets , rather than a single unique set , of chemical abundances are predicted for identical input cloud parameters such as the total gas density , the cosmic - ray ( or x - ray ) ionization rate , and the gas - phase supply of heavy elements . under such circumstances , the solution that is converged to in a numerical simulation , and perhaps , the actual steady - state of a real physical system , depend on the initial conditions and history of the gas .
the subject of bistability begins with pineau des forets et al . |
4,584 | Suppose that you have an abstract for a scientific paper: the eigenstate problem of the jaynes - cummings model on the basis of complete hamiltonian , including the center - of -mass kinetic energy operator , is treated .
the energy spectrum and wave functions in standing - wave ( sw)- and counterpropagating waves ( cpw)- cases are calculated and compared with each other .
it is shown that in cpw - case i ) the atomic momentum distribution is asymmetric and somewhat narrower in general ; ii ) the concept of quasimomentum is not applicable and instead the ordinary momentum concerns the problem ; iii ) atomic and photonic state distributions are self - consistent , and , in consequence iiii ) mean number of photons in the counterpropagating traveling waves and mean atomic momentum match .
explicit analytic expressions for energy eigenvalues and eigenfunctions are found in tavis -cummings - type approximation [ phys .
rev .
170 , 379(1968 ) ] and is pointed , that it implies only the bounded - like states for atomic center - of - mass motion .
it is also shown that if the recoil energy is taken into account , the doppleron resonance is split into two branches , one of which diverges to bragg - like resonance in the high - order range . .
And you have already written the first three sentences of the full article: the key scheme of cavity quantum electrodynamics ( qed)@xcite , modern atom optics and interferometry @xcite is the resonant interaction of an atom with cavity fields , created as standing or counterpropagating waves . the first type ( with respective quantization on the sw basis ) is attained in two plane - parallel - mirror cavities ( in short , cavity ) , while the second type ( with respective cpw - quantization ) is attained in three or more mirror cavities ( ring cavities ) .
it is well known , in addition , that for classical picture of fields , these two representations are equivalent in the sense , that the sw can always be presented as a superposition of two counterpropagating travelling waves . in the quantum theory , nevertheless , they are divers@xcite , including the hamiltonians of interaction . hence it needs to be ascertained : are the diversities only quantitative or qualitative too , and how much are they for these or that circumstances and processes .
note , that it presents not only an academic interest , since in the microcavities ( @xmath0 ) several dozens of photons can induce strong optical nonlinearities for dipole - allowed optical transitions ..
Please generate the next two sentences of the article | as far as we know , elucidation of physical aspects of mentioned incongruity had been done in paper @xcite , taking as an example the process of near - resonant coherent diffraction of atomic matter - waves by a space - periodic laser radiation field , known as near - resonant kapitza - dirac diffraction@xcite . by means of numerical solution of the master equations for atomic probability amplitudes ,
the existence of evident differences between sw and cpw diffraction patterns was shown , in strictly quantum domain of cavity fields ( the mean number of photons in cavities was chosen one ) . |
4,585 | Suppose that you have an abstract for a scientific paper: we present high - quality keck telescope spectroscopic observations of the two metal - deficient blue compact dwarf ( bcd ) galaxies tol 1214277 and tol 65 .
these data are used to derive the heavy - element and helium abundances .
we find that the oxygen abundances in tol 1214277 and tol 65 are the same , 12 + log o / h = 7.54 @xmath0 0.01 , or @xmath1/24 , despite the different ionization conditions in these galaxies .
the nitrogen - to - oxygen abundance ratio in both galaxies is log n / o = [email protected] and lies in the narrow range found for the other most metal - deficient bcds .
we use the five strongest he i emission lines @xmath2@xmath23889 , 4471 , 5876 , 6678 and 7065 , to correct self - consistently their intensities for collisional and fluorescent enhancement mechanisms and to derive the @xmath3he abundance .
underlying stellar absorption is found to be important for the he i @xmath24471 emission line in both galaxies , being larger in tol 65 .
the weighted @xmath3he mass fractions in tol 1214277 and tol 65 are respectively @xmath4 = 0.2458 @xmath0 0.0039 and 0.2410 @xmath0 0.0050 when the three he i emission lines , @xmath2@xmath24471 , 5876 and 6678 , are used , and are , respectively , 0.2466 @xmath0 0.0043 and 0.2463 @xmath0 0.0057 when the he i 4471 emission line is excluded .
these values are in very good agreement with recent measurements of the @xmath3he mass fraction in others of the most metal - deficient bcds by izotov and coworkers .
we find that the combined effect of the systematic uncertainties due to the underlying he i stellar absorption lines , ionization and temperature structure of the h ii region and collisional excitation of the hydrogen emission lines is likely small , not exceeding @xmath5 2% ( the error is 2@xmath6 ) .
our results support the validity of the standard big bang model of nucleosynthesis . .
And you have already written the first three sentences of the full article: in the standard big bang model of nucleosynthesis ( sbbn ) , the light isotopes d , @xmath7he , @xmath3he and @xmath8li were produced by nuclear reactions a few minutes after the birth of the universe .
given the number of light neutrino species @xmath9 = 3 and the neutron lifetime , the abundances of these light elements depend on one cosmological parameter only , the baryon - to - photon ratio @xmath10 , which in turn is directly related to the density of ordinary baryonic matter @xmath11 .
the ideal objects for determination of the primordial helium abundance are blue compact dwarf ( bcd ) galaxies ..
Please generate the next two sentences of the article | these dwarf systems are the least chemically evolved galaxies known , so they contain very little helium manufactured by stars after the big bang .
because the big bang production of @xmath3he is relatively insensitive to the density of matter , the primordial abundance of @xmath3he must be determined to very high precision ( better than a few percent relative accuracy ) in order to put useful constraints on @xmath12 . |
4,586 | Suppose that you have an abstract for a scientific paper: graber , harris and starr proved , when @xmath0 , the irreducibility of the hurwitz space @xmath1 which parametrizes degree @xmath2 coverings of a smooth , projective curve @xmath3 of genus @xmath4 , simply branched in @xmath5 points , with full monodromy group @xmath6 .
we sharpen this result and prove that @xmath1 is irreducible if @xmath7 and in the case of elliptic @xmath3 if @xmath8 .
we extend the result to coverings simply branched in all but one point of the discriminant . fixing the ramification multiplicities over the special point
we prove that the corresponding hurwitz space is irreducible if the number of simply branched points is @xmath9 .
we study also simply branched coverings with monodromy group @xmath10 and when @xmath5 is large enough determine the corresponding connected components of @xmath11 .
our results are based on explicit calculation of the braid moves associated with the standard generators of the @xmath5-strand braid group of @xmath3 . .
And you have already written the first three sentences of the full article: let @xmath3 be a smooth , connected , projective complex curve of genus @xmath12 .
let @xmath11 be the hurwitz space which parametrizes degree @xmath2 coverings of @xmath3 simply branched in @xmath5 points . a classical result of hurwitz @xcite states that @xmath13 is irreducible .
more generally one can consider coverings of @xmath14 which are simply branched in all but one point of the discriminant ..
Please generate the next two sentences of the article | fixing the ramification multiplicities over the special point one obtains a corresponding hurwitz space which turns out to be irreducible as well ( see @xcite , @xcite , @xcite ) .
coverings of curves of positive genus were studied by graber , harris and starr in @xcite . |
4,587 | Suppose that you have an abstract for a scientific paper: quantum computers , which process information encoded in quantum mechanical systems , hold the potential to solve some of the hardest computational problems . a substantial obstacle for the further development of quantum computers
is the fact that the life time of quantum information is usually too short to allow practical computation . a promising method to increase the life time , known as dynamical decoupling , consists of applying a periodic series of inversion pulses to the quantum bits . in the present review ,
we give an overview of this technique and compare different pulse sequences proposed earlier .
we show that pulse imperfections , which are always present in experimental implementations , limit the performance of dynamical decoupling .
the loss of coherence due to the accumulation of pulse errors can even exceed the perturbation from the environment .
this effect can be largely eliminated by a judicious design of pulses and sequences .
the corresponding sequences are largely immune to pulse imperfections and provide an increase of the coherence time of the system by several orders of magnitude . .
And you have already written the first three sentences of the full article: during the last decade , it was shown that quantum mechanical systems have the potential for processing information more efficiently than classical systems @xcite .
however , it remains difficult to realize this potential because quantum systems are extremely sensitive to perturbations .
these perturbations come from external degrees of freedom or from the finite precision with which the systems can be realized and controlled by external fields ..
Please generate the next two sentences of the article | this loss of quantum information to the environment is called decoherence @xcite .
different results show that a state is more sensitive to decoherence as the number of qubits increases @xcite . |
4,588 | Suppose that you have an abstract for a scientific paper: we present experimental heat transport measurements of turbulent rayleigh - bnard convection with rotation about a vertical axis .
the fluid , water with prandtl number ( @xmath0 ) about 6 , was confined in a cell which had a square cross section of 7.3 @xmath17.3 cm and a height of 9.4 cm .
heat transport was measured for rayleigh numbers @xmath2 ra @xmath3 and taylor numbers @xmath4 ta @xmath5 .
we show the variation of normalized heat transport , the nusselt number , at fixed dimensional rotation rate @xmath6 , at fixed ra varying ta , at fixed ta varying ra , and at fixed rossby number ro .
the scaling of heat transport in the range @xmath7 to about @xmath8 is roughly 0.29 with a ro dependent coefficient or equivalently is also well fit by a combination of power laws of the form @xmath9 .
the range of ra is not sufficient to differentiate single power law or combined power law scaling .
the overall impact of rotation on heat transport in turbulent convection is assessed . .
And you have already written the first three sentences of the full article: turbulent thermal convection plays a key role in many of the phenomena associated with geophysical and astrophysical fluid dynamics @xcite as well as providing a well - posed problem for the study of fundamental fluid dynamics @xcite . in several important examples including oceanic deep convection @xcite and convection in stars @xcite and giant planets @xcite ,
the effects of rotation are critical in determining the nature of the fluid motion .
rotation also provides an additional parameter for understanding the origin of heat transport scaling in turbulent convection , a topic of tremendous experimental activity in recent years @xcite . in comparison ,.
Please generate the next two sentences of the article | the research efforts applied to rotating turbulent convection have been rather modest arising from the pioneering theoretical work of chandrasekhar @xcite .
experimental measurements of heat transport in rotating convection include the seminal work of rossby @xcite and later studies that also had qualitative flow visualization @xcite . |
4,589 | Suppose that you have an abstract for a scientific paper: we show that the algebraic dimension of a twistor space over @xmath0 can not be two if @xmath1 and the fundamental system ( i.e.the linear system associated to the half - anti - canonical bundle , which is available on any twistor space ) is a pencil .
this means that if the algebraic dimension of a twistor space on @xmath0 , @xmath1 , is two , then the fundamental system either is empty or consists of a single member .
the existence problem for a twistor space on @xmath0 with algebraic dimension two is open for @xmath1 . .
And you have already written the first three sentences of the full article: if @xmath2 is a compact complex manifold , the algebraic dimension of @xmath2 , usually denoted by @xmath3 , is defined to be the complex dimension of a projective algebraic variety , the rational function field of which is isomorphic to that of @xmath2 .
we always have @xmath4 , and in case of equality , @xmath2 is called moishezon .
any projective algebraic manifold is moishezon . in the other extreme case ,.
Please generate the next two sentences of the article | @xmath5 , @xmath2 has no non - constant rational function .
not so many compact differential manifolds admit complex structures whose algebraic dimension ranges from zero to half of its real dimension . |
4,590 | Suppose that you have an abstract for a scientific paper: @xcite found a very tight relationship between the f10.7 solar radio flux and the sunspot number and suggested using the flux for an objective calibration of the sunspot number .
he suggested that if this relationship changed later on , the sunspot number should be re - calibrated , assuming that the calibration must have drifted with time .
i repeat his analysis using data up to the present and it is , indeed , clear that the relationship has changed significantly
. this could be due to a drift of the calibration or to a secular change in the visibility of sunspots , or both . .
And you have already written the first three sentences of the full article: the sunspot number is the solar index most frequently used in the study of long - term solar activity variations and , even more so , in solar - terrestrial relation studies .
the relative sunspot number was defined by rudolf wolf @xcite as @xmath0 where @xmath1 is the number of sunspot groups , @xmath2 is the total number of ` spots ' in all the groups on the visible disk , and @xmath3 is a scale factor to bring the number on to wolf s scale ( thus @xmath4 for wolf himself ) .
it would seem that @xmath1 and @xmath2 should be uniquely determined simply by counting and that a @xmath3-factor would not be necessary ..
Please generate the next two sentences of the article | however , different observers - even using the same instrument - may differ in how they overcome variable seeing and arrive at different numbers of groups .
even more so for the number of spots , where the very definition of what should be counted as a spot may vary from observer to observer . |
4,591 | Suppose that you have an abstract for a scientific paper: a generalized depolarizing channel acts on an @xmath0-dimensional quantum system to compress the `` bloch ball '' in directions ; it has a corresponding compression vector .
we investigate the geometry of these compression vectors and prove a conjecture of dixit and sudarshan @xcite , namely that when ( i.e. the system consists of @xmath1 qubits ) and we work in the pauli basis then the set of all compression vectors forms a simplex .
we extend this result by investigating the geometry in other bases ; in particular we find precisely when the set of all compression vectors forms a simplex . .
And you have already written the first three sentences of the full article: perhaps the simplest model of noise in a quantum system is that of the isotropic depolarizing channel @xmath2 where with probability probability a quantum state @xmath3 is left untouched while with probability @xmath4 it is mapped to the completely mixed state @xmath5 @xmath6 this channel results in the bloch `` ball '' being compressed isotropically by a factor of .
one can imagine a slightly more complicated noise model whereby the noise compresses the bloch `` ball '' anisotropically along axes which are defined by the basis we choose to work in and it is this setting which we investigate below .
the amounts by which we compress along each axis are called the * compression coefficients * and these form the components of the * compression vector*. we investigate the geometric properties of the set of all compression vectors and in particular we ask `` when does this set form a simplex ? '' these * generalized depolarizing channels * ( also called * anisotropic depolarizing channels * ) form a broad class of channels which can be realized experimentally ( see for example @xcite ) ; in the single qubit case they include the bit - flip and phase - flip channels ..
Please generate the next two sentences of the article | it is worth noting that _ any _ quantum channel ( including the use of a spin chain as a quantum channel @xcite ) can be turned into a generalized depolarizing channel as follows : alice sends one half of a maximally entangled bipartite state down the channel to bob ; the resulting shared state is a mixed bipartite state which is ( excepting very special cases ) not maximally entangled ; alice and bob can now use this shared resource to attempt teleportation @xcite of an unknown @xmath0-dimensional quantum state @xmath3 ; the teleportation protocol then acts as a generalized depolarizing channel on this state @xmath3 @xcite .
this work is organized as follows : section [ sec : problem ] gives some precise definitions and describes in detail the problem we solve . |
4,592 | Suppose that you have an abstract for a scientific paper: we study the sensitivity of icecube / deepcore detector to dark matter annihilations in the earth core .
we focus on annihilation modes @xmath0 , and @xmath1 .
both track and cascade events are considered in our analysis . by fixing the dark matter annihilation cross section @xmath2 at some nominal values , we study the sensitivity of icecube / deepcore detector to dark matter spin - independent cross section @xmath3 for @xmath4 ranging from few tens of gev to 10 tev . this sensitivity is compared with the existing icecube 79-string constraint on the same cross section , which was obtained by searching for dark matter annihilations in the sun .
we compare this sensitivity to dark matter direct detection results as well , in particular the xenon100 ( 2012 ) limit and the parameter regions preferred by dama and cresst - ii experiments .
we also present icecube / deepcore sensitivity to @xmath5 as a function of @xmath4 by fixing @xmath3 at xenon100 ( 2012 ) and xenon1 t limits , respectively .
this sensitivity is compared with the preferred dark matter parameter range derived from the combined fitting to pamela and ams02 positron fraction data .
we conclude that the search for dark matter annihilations in the earth core provides competitive constraints on @xmath3 and @xmath5 in the case of low - mass dark matter . particularly , the expected constraint on @xmath6 for 5 years of data taking in icecube / deepcore is more stringent than the current icecube 79-string limit mentioned above .
= = = = = = = = = ==================== = ======= .
And you have already written the first three sentences of the full article: evidences for the dark matter ( dm ) are provided by many astrophysical observations , although the nature of dm is yet to be uncovered .
the most popular candidates for dm are weak interacting massive particles ( wimp ) , which we shall assume in this work .
dm can be detected either directly or indirectly with the former observing the nucleus recoil as dm interacts with the target nuclei in the detector and the latter detecting final state particles resulting from dm annihilations or decays ..
Please generate the next two sentences of the article | the direct detection is possible because that the dark matter particles constantly bombard the earth as the earth sweeps through the local halos .
as just stated , the direct detection experiments record the nuclei recoil energy of nuclei - wimps scattering . at present |
4,593 | Suppose that you have an abstract for a scientific paper: helices are a key folding motif in protein structure .
the question which factors determine helix stability for a given polypeptide or protein is an ongoing challenge .
here we use van der waals corrected density - functional theory to address a part of this question in a bottom - up approach . we show how intrinsic helical structure is stabilized with length and temperature for a series of experimentally well studied unsolvated alanine based polypeptides , ac - ala@xmath0-lysh@xmath1 . by exploring extensively the conformational space of these molecules
, we find that helices emerge as the preferred structure in the length range @xmath2=4 - 8 not just due to enthalpic factors ( hydrogen bonds and their cooperativity , van der waals dispersion interactions , electrostatics ) , but importantly also by a vibrational entropic stabilization over competing conformers at room temperature .
the stabilization is shown to be due to softer low - frequency vibrational modes in helical conformers than in more compact ones .
this observation is corroborated by including anharmonic effects explicitly through _ ab initio _ molecular dynamics , and generalized by testing different terminations and considering larger helical peptide models . .
And you have already written the first three sentences of the full article: polypeptide helices are a key secondary structure motif in a wide range of proteins @xcite .
it is well known that some amino acids ( e.g. , alanine ) exhibit a stronger helix propensity than others @xcite , but the fact that the helical structure is so abundant in proteins is still intriguing . from a thermodynamic point of view , there are at least two possible limits in which helices compete with other structure prototypes . towards high temperature ,
one expects the transition to a random coil @xcite , which should become entropically favored as the temperature increases . towards low temperature , however , helices may themselves compete with other enthalpically stable conformations ..
Please generate the next two sentences of the article | however , in the most interesting regime , namely intermediate , physiological temperatures , stability may be determined by a delicate balance between enthalpy and entropy @xcite .
we here unravel this balance quantitatively for the emergence of helical structure in a particularly well studied series of unsolvated polyalanine based peptides ac - ala@xmath0-lysh@xmath1 , @xmath2=4 - 8 @xcite . |
4,594 | Suppose that you have an abstract for a scientific paper: the ab - initio many - body method suggested in the preceding paper is applied to the 3d transition metals fe , co , ni , and cu .
we use a linearized muffin - tin orbital calculation to determine bloch functions for the hartree one - particle hamiltonian , and from these obtain maximally localized wannier functions . within this wannier basis
all relevant one - particle and two - particle coulomb matrix elements are calculated . the resulting second - quantized many - body hamiltonian with ab - initio parameters
is studied within the simplest many - body approximation , namely the unscreened , selfconsistent , hartree - fock approximation ( hfa ) .
we present these hfa results , which we believe are the first to have been done for crystalline 3d transition metals , and compare them with those obtained from the standard local ( spin ) density approximation ( lsda ) within density functional theory ( dft ) .
although the d - bands sit considerably lower within hfa than within l(s)da , the exchange splitting and magnetic moments for ferromagnetic fe , co , and ni are only slightly larger in hfa than what is obtained experimentally or within lsda .
the hfa total energies are lower than the corresponding l(s)da calculations . .
And you have already written the first three sentences of the full article: in the preceding paper@xcite we suggested a new method for ab - initio electronic - structure calculations of solids .
the main steps of this procedure are : 1 .
perform a conventional , self - consistent , band - structure calculation for an effective one - particle hamiltonian , namely , the hartree hamiltonian , to obtain a suitable basis set of bloch functions . 2 . by taking into account only a finite number @xmath0 of bands.
Please generate the next two sentences of the article | one chooses a truncated one - particle hilbert space .
the marzari - vanderbilt@xcite algorithm is then used to construct a maximally localized set of wannier functions , which span the same truncated one - particle hilbert space . |
4,595 | Suppose that you have an abstract for a scientific paper: we report the detection of @xmath0-ray pulsations ( @xmath1 gev ) from psr j2229 + 6114 and psr j1048@xmath25832 , the latter having been detected as a low - significance pulsar by egret .
data in the @xmath0-ray band were acquired by the large area telescope aboard the _ fermi gamma - ray space telescope _ , while the radio rotational ephemerides used to fold the @xmath0-ray light curves were obtained using the green bank telescope , the lovell telescope at jodrell bank , and the parkes telescope .
the two young radio pulsars , located within the error circles of the previously unidentified egret sources 3eg j1048@xmath25840 and 3eg j2227 + 6122 , present spin - down characteristics similar to the vela pulsar .
psr j1048@xmath25832 shows two sharp peaks at phases @xmath3 and @xmath4 relative to the radio pulse confirming the egret light curve , while psr j2229 + 6114 presents a very broad peak at phase @xmath5 .
the @xmath0-ray spectra above 0.1 gev of both pulsars are fit with power laws having exponential cutoffs near 3 gev , leading to integral photon fluxes of @xmath6@xmath7s@xmath8 for psr j1048@xmath25832 and @xmath9@xmath7s@xmath8 for psr j2229 + 6114 .
the first uncertainty is statistical and the second is systematic .
psr j1048@xmath25832 is one of two lat sources which were entangled together as 3eg j1048@xmath25840 .
these detections add to the growing number of young @xmath0-ray pulsars that make up the dominant population of gev @xmath0-ray sources in the galactic plane . .
And you have already written the first three sentences of the full article: the nature of unidentified high - energy @xmath0-ray sources in the galaxy was one of the major unanswered questions at the end of the egret era .
the third egret catalog contained 170 unidentified sources , 74 of which were at galactic latitude @xmath10@xcite .
rotation - powered pulsars are believed to dominate the galactic @xmath0-ray source population ( e.g. @xcite ) , but their visibility is linked to their beam patterns . soon after launch , the _ fermi gamma - ray space telescope _ began to unveil many 3eg sources , discovering the radio - quiet pulsar in the cta1 supernova remnant associated with 3eg j0010 + 7309 @xcite , detecting the radio - loud pulsar psr j2021 + 3651 ( associated with 3eg j2021 + 3716 ) @xcite , seen independently by _ agile _.
Please generate the next two sentences of the article | @xcite , as well as the radio pulsar psr j1028@xmath25819 , associated with 3eg j1027@xmath25817 @xcite and new populations of radio - quiet @xmath0-ray pulsars , detectable using blind search techniques @xcite . for the pulsars detected in @xmath0 rays ,
the bulk of the electromagnetic power output is in high energies . |
4,596 | Suppose that you have an abstract for a scientific paper: infrared power corrections for the average thrust @xmath0 in @xmath1 annihilation are analyzed in the framework of renormalon resummation , motivated by analogy with the skeleton expansion in qed and the blm approach . performing the `` massive gluon '' renormalon
integral a renormalization scheme invariant result is obtained .
we find that a major part of the discrepancy between the known next - to - leading order ( nlo ) calculation and experiment can be explained by resummation of higher order perturbative terms .
this fact does not preclude the infrared finite coupling interpretation with a substantial @xmath2 power term .
fitting the regularized perturbative sum plus a @xmath2 term to experimental data yields .
loop loop .
And you have already written the first three sentences of the full article: power corrections to event shape observables in @xmath1 annihilation have been an active field of research in the recent years .
event shapes , as opposed to other inclusive observables , do not have an operator product expansion , so there is no established field theoretic framework to analyse them beyond the perturbative level . on the other hand ,
the experimental data now available cover a wide range of scales and thus could provide an opportunity to test qcd and extract a precise value of @xmath3 ..
Please generate the next two sentences of the article | the state of the art in perturbative calculations of average event shape variables is @xmath4 , i.e. nlo . it turns out that experimental data are not well described by these perturbative expressions , unless explicit power corrections , that may be associated with hadronization , are introduced .
renormalon phenomenology allows to predict the form of the power terms while their magnitude is determined by experimental fits . in the work reported here |
4,597 | Suppose that you have an abstract for a scientific paper: we use a stellar binary population synthesis code to find the lifetimes and velocities of several types of possible grb progenitors : double neutron stars , black hole neutron stars , black hole white dwarfs , helium star mergers . assuming that they are born in different types of galaxies we compute their spatial distribution and compare it with the observed locations of grb afterglows within their hosts .
we discuss constraints on the compact object merger model of grbs imposed by this comparison and find that the observations of afterglows and their host galaxies appear inconsistent with the grb compact object merger model . .
And you have already written the first three sentences of the full article: in the last few years the astronomical community has moved much closer to unveiling the nature of grbs .
the discovery of afterglows and identification of host galaxies for several bursts clearly links grbs to some type of stellar events .
yet the nature of these events is unknown , and we still do not know what the grb central engines are ..
Please generate the next two sentences of the article | observations of grb host galaxies and precise locations of grbs within hosts provide a tool to test some of the possible central engine models . in this paper
we discuss the consistency between the current observations and the results of binary population synthesis . |
4,598 | Suppose that you have an abstract for a scientific paper: we show that there is a class of regular charged black hole with a charged de sitter core similar to the de sitter - schwarzschild black hole .
one can show that the total energy momentum tensor for the static and spherically symmetric photon field can be made conserved even the coulomb like energy momentum tensor for photon is not conserved alone .
possible impact and the numerical solutions of the charged black hole will be shown in this paper . .
And you have already written the first three sentences of the full article: the penrose cosmic censorship states that : if singularities predicted by general relativity @xcite occur , they must be dressed by event horizons @xcite .
hence , the search of the regular black hole solutions has been a focus of research interests lately @xcite .
in fact , the study of global regularity of black hole solutions is important for the understanding of the final state of the gravitational collapse from some initially regular configurations . earlier work on regular black hole models can be found in references @xcite ..
Please generate the next two sentences of the article | these regular solutions are referred to as `` bardeen black holes '' @xcite .
in addition , regular black hole solutions to einstein equations with various physical sources were reported in @xcite . the other approaches to avoid the singularities are the search of some more generalized theories , for example , the string / m theory @xcite . |
4,599 | Suppose that you have an abstract for a scientific paper: the episodic , irregular and asynchronous nature of medical data render them difficult substrates for standard machine learning algorithms .
we would like to abstract away this difficulty for the class of time - stamped categorical variables ( or _ events _ ) by modeling them as a renewal process and inferring a probability density over continuous , longitudinal , nonparametric intensity functions modulating that process .
several methods exist for inferring such a density over intensity functions , but either their constraints and assumptions prevent their use with our potentially bursty event streams , or their time complexity renders their use intractable on our long - duration observations of high - resolution events , or both .
in this paper we present a new and efficient method for inferring a distribution over intensity functions that uses direct numeric integration and smooth interpolation over gaussian processes .
we demonstrate that our direct method is up to twice as accurate and two orders of magnitude more efficient than the best existing method ( thinning ) .
importantly , the direct method can infer intensity functions over the full range of bursty to memoryless to regular events , which thinning and many other methods can not .
finally , we apply the method to clinical event data and demonstrate the face - validity of the abstraction , which is now amenable to standard learning algorithms .
= 1 .
And you have already written the first three sentences of the full article: one of the hurdles for identifying clinically meaningful patterns in medical data is the fact that much of that data is sparsely , irregularly , and asynchronously observed , rendering it a poor substrate for many pattern recognition algorithms .
a large class of this problematic data in medical records is time - stamped categorical data such as billing codes .
an icd-9 billing code , for example , with value 714.0 ( rheumatoid arthritis ) gets attached to a patient record every time the patient makes contact with the healthcare system for a problem or activity related to her arthritis ..
Please generate the next two sentences of the article | this could be an outpatient doctor visit , a laboratory test , a physical therapy visit , the discharge event of an inpatient stay , or any other billable event .
these events occur at times that are in general independent from events for other conditions . |
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