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6,700 | Suppose that you have an abstract for a scientific paper: let @xmath0 be a weighted graph with a finite vertex set @xmath1 , with a symmetric matrix of nonnegative weights @xmath2 and with laplacian @xmath3 .
let @xmath4 be a symmetric kernel defined on the vertex set @xmath1 .
consider @xmath5 i.i.d .
observations @xmath6 , where @xmath7 are independent random vertices sampled from the uniform distribution in @xmath1 and @xmath8 is a real valued response variable such that @xmath9 .
the goal is to estimate the kernel @xmath10 based on the data @xmath11 and under the assumption that @xmath10 is low rank and , at the same time , smooth on the graph ( the smoothness being characterized by discrete sobolev norms defined in terms of the graph laplacian ) .
we obtain several results for such problems including minimax lower bounds on the @xmath12-error and upper bounds for penalized least squares estimators both with nonconvex and with convex penalties . .
And you have already written the first three sentences of the full article: we study a problem of estimation of a symmetric kernel @xmath13 defined on a large weighted graph with a vertex set @xmath1 and @xmath14 based on a finite number of noisy linear measurements of @xmath10 . for simplicity , assume that these are the measurements of randomly picked entries of @xmath15 matrix @xmath16 , which is a standard sampling model in matrix completion .
more precisely , let @xmath17 be @xmath5 independent copies of a random triple @xmath18 , where @xmath19 are independent random vertices sampled from the uniform distribution @xmath20 in @xmath1 , and @xmath21 is a `` measurement '' of the kernel @xmath10 at a random location @xmath22 in the sense that @xmath23 . in what follows
, we assume that , for some constant @xmath24 , @xmath25 a.s . , which implies that @xmath26 ..
Please generate the next two sentences of the article | the target kernel @xmath10 is to be estimated based on its i.i.d .
measurements @xmath17 . |
6,701 | Suppose that you have an abstract for a scientific paper: regular generalizations of spherically and axially symmetric metrics and their properties are considered .
newton gravity law generalizations are reduced for null geodesics . .
And you have already written the first three sentences of the full article: according to the birkgoff theorem @xcite _ the metric of a vacuum spherically symmetric space time is static , singular in the origin , unique and in spherically symmetric coordinates has the well - known schwarzschild form _ ( when @xmath0 signature form is chosen ) @xmath1 where @xmath2 is the schwarzschild radius .
we define the regularity of a metric at a point as i ) an indefinite differentiability of all metric components at this point ; ii ) the condition @xmath3 holds true at this point relative to any coordinate system associated with our system by a unique and continuous transformation .
petrov @xcite has shown a counterexample of the metric contradicting the birkgoff theorem @xmath4 where @xmath5 ..
Please generate the next two sentences of the article | metric ( [ e02 ] ) is not static .
here it is necessary to note that ( [ e01 ] ) and ( [ e02 ] ) are defined in the same coordinate system . |
6,702 | Suppose that you have an abstract for a scientific paper: we study the possibility that the very broad ( @xmath0 1500 km s@xmath1 ) and luminous ( @xmath2 ) [ oiii ] line emission observed in the globular cluster rz 2109 might be explained with the photoionization of nova ejecta by the bright ( @xmath3 ) x - ray source hosted in the same globular cluster .
we find that such scenario is plausible and explains most of the features of the rz 2109 spectrum ( line luminosity , absence of h emission lines , peculiar asymmetry of the line profile ) ; on the other hand , it requires the nova ejecta to be relatively massive ( @xmath4 ) , and the nova to be located at a distance @xmath5 from the x - ray source .
we also predict the time evolution of the rz 2109 line emission , so that future observations can be used to test this scenario .
novae , cataclysmic variables - galaxies : individual ( ngc 4472 ) - galaxies : star clusters : individual ( rz 2109 ) - x - rays : binaries - ism : jets and outflows .
And you have already written the first three sentences of the full article: many x - ray sources ( xrss ) are inside globular clusters ( gcs ; e.g. heinke 2011 ) , but only five of them unambiguosly host a black hole ( bh ; maccarone et al .
2007 , hereafter m07 ; brassington et al . 2010 ; shih et al . 2010 ; maccarone et al . 2011 ; irwin et al .
2010 , hereafter i10 ; see king 2011 for an alternative explanation ) ..
Please generate the next two sentences of the article | these five objects were observed as luminous xrss ( @xmath6 ) with strong variability ( so that blending is excluded ; kalogera et al .
the spectra of at least two of their host gcs are quite peculiar . |
6,703 | Suppose that you have an abstract for a scientific paper: we study a chain of magnetic moments exchange coupled to a conventional three dimensional superconductor . in the normal state the chain orders into a collinear configuration , while in the superconducting phase we find that ferromagnetism is unstable to the formation of a magnetic spiral state . beyond weak exchange coupling the spiral wavevector
greatly exceeds the inverse superconducting coherence length as a result of the strong spin - spin interaction mediated through the subgap band of yu - shiba - rusinov states .
moreover , the simple spin - spin exchange description breaks down as the subgap band crosses the fermi energy , wherein the spiral phase becomes stabilized by the spontaneous opening of a @xmath0wave superconducting gap within the band .
this leads to the possibility of electron - driven topological superconductivity with majorana boundary modes using magnetic atoms on superconducting surfaces .
the prospect of performing topological quantum computation @xcite has stimulated intense investigations into condensed - matter systems harboring majorana bound states @xcite .
one potential platform involves magnetic atoms arranged in a regular lattice on an @xmath1wave superconducting substrate @xcite .
this system has received a renewed interest due to recent scanning tunneling microscopy ( stm ) data possibly supporting the existence of majorana bound states in a self - assembled one - dimensional ( 1d ) array of atomically - spaced fe atoms on the surface of superconducting pb @xcite .
we focus on the case of an stm - assembled magnetic atom chain whose spacing is several substrate lattice sites @xcite , where the overlap of atomic wavefunctions is negligible . in that case
each atom acts as an isolated magnetic moment giving rise to localized , sub - gap yu - shiba - rusinov ( ysr ) states @xcite within the superconductor .
overlap between ysr states leads to the formation of an effectively spinless sub - gap band that can undergo a topological superconducting....
And you have already written the first three sentences of the full article: we start from the bdg hamiltonian ( eq . ( [ eq : h ] ) of the main text ) and
compute the thermodynamic potential @xmath129 at inverse temperature @xmath130 using the quantum partition function @xmath131 .
this allows us to extrapolate to the groundstate energy in the limit @xmath132 . following ref ..
Please generate the next two sentences of the article | @xcite ( see p. 254 ) , we introduce the real parameter @xmath78 multiplied onto the exchange part of the bdg hamiltonian , @xmath133 written with @xmath134 nambu matrices @xmath135 . from this definition ,
the change of thermodynamic potential due to the spin lattice can be found as an integral of @xmath136 over @xmath78 : @xmath137.\label{eq : trvg}\end{aligned}\ ] ] here we use the matrix notation @xmath138 and @xmath139 , with the nambu matrix structure being implied . |
6,704 | Suppose that you have an abstract for a scientific paper: we study the validity of the born - oppenheimer approximation in chaotic dynamics . using numerical solutions of autonomous fermi accelerators
, we show that the general adiabatic conditions can be interpreted as the narrowness of the chaotic region in phase space . .
And you have already written the first three sentences of the full article: the born - oppenheimer approximation is a method which deals with a coupled system of heavy and light objects@xcite . from atomic physics to nuclear physics
, it has played an important role .
moreover , the importance of this method gets greater as the necessity of the adiabatic control of quantum states arises in the quantum information science@xcite ..
Please generate the next two sentences of the article | nevertheless , the criteria of the validity of the method is not well defined yet , even still controversial in some aspects@xcite .
therefore , more theoretical work is needed through applications to specific models . in this paper , we focused on the effect of chaotic dynamics in the born - oppenheimer approximation method . |
6,705 | Suppose that you have an abstract for a scientific paper: in this work , we study the motions in the region around the equilateral lagrangian equilibrium points @xmath0 and @xmath1 , in the framework of the circular planar restricted three - body problem ( hereafter , cprtbp ) .
we design a semi - analytic approach based on some ideas by garfinkel in @xcite : the hamiltonian is expanded in poincar
delaunay coordinates and a suitable average is performed .
this allows us to construct ( quasi ) invariant tori that are moderately far from the lagrangian points l4-l5 and approximate wide tadpole orbits .
this construction provides the tools for studying optimal transfers in the neighborhood of the equilateral points , when instantaneous impulses are considered .
we show some applications of the new averaged hamiltonian for the earth - moon system , applied to the setting - up of some transfers which allow to enter in the stability region filled by tadpole orbits . .
And you have already written the first three sentences of the full article: for the design of simple transfers in astrodynamics , hohmann transfers are widely used .
they consist basically in a maneuvre in a system represented by a two body problem ( 2bp ) and their solutions , consequently given by keplerian ellipses . starting from a circular orbit around a main body ,
a transfer to a different ( inner or outer ) circular orbit can be achieved with just two different impulses of properly defined sense and magnitude ( see e.g. @xcite ) . in cases where 2bp is not a suitable approximation ,.
Please generate the next two sentences of the article | a similar approach can be considered with a different simplified version of the hamiltonian representing the system .
the aim of the method lays on the idea of designing a transfer between orbits that are _ exact solutions _ of an _ |
6,706 | Suppose that you have an abstract for a scientific paper: background : : one - nucleon removal reactions at or above the fermi energy are important tools to explore the single - particle structure of exotic nuclei .
experimental data must be compared with calculations to extract structure information , evaluate correlation effects in nuclei or determine reaction rates for nuclear astrophysics .
however , there is insufficient knowledge to calculate accurately the cross sections for these reactions .
purpose : : we evaluate the contributions of the final state interaction ( fsi ) and of the medium modifications of the nucleon - nucleon interactions and obtain the shapes and magnitudes of momentum distributions .
such effects have been often neglected in the literature .
method : : calculations for reactions at energies 35 - 1000 mev / nucleon are reported and compared to published data . for consistency ,
the state - of - the - art eikonal method for stripping and diffraction dissociation is used .
results : : we find that the two effects are important and their relative contributions vary with the energy and with the atomic and mass number of the projectile involved .
conclusions : : these two often neglected effects modify considerably the one - nucleon removal cross sections .
as expected , the effect are largest at lower energies , around 50 mev / nucleon and on heavy targets . .
And you have already written the first three sentences of the full article: nucleon knockout reactions in nuclear collisions at and above the fermi energy in nuclei have become an important tool to determine the occupancy of single - particle states and the correlation effects in the nuclear many - body system ( see , e.g. refs .
@xcite ) . in peripheral ,
sudden collisions of fast - moving projectiles with a target nucleus , a single nucleon is removed from the projectile , producing projectile - like residues in the exit channel , which are measured ..
Please generate the next two sentences of the article | referred to the center - of - mass system of the projectile , the transferred momentum is @xmath0 . for the knockout reactions in the sudden approximation , this must equal the momentum of the struck nucleon before the collision .
the standard reaction models assume that the ground state of the projectile of spin and parity @xmath1 can be approximated by a superposition of configurations of the form @xmath2^{j^{\pi}}$ ] where @xmath3 denote the core states and the @xmath4 are the quantum numbers for the single particle wave functions in a spherical mean field potential . |
6,707 | Suppose that you have an abstract for a scientific paper: the belle detector operated at kekb b - factory in 1999 - 2010 was one of the most remarkable experiments in the field of elementary particle physics of the last decades .
the belle successor , belle ii collaboration , is aimed to operate the belle ii detector at superkekb factory at 40 times higher luminosity . increased
luminosity imposes new requirements on the detector elements : they have to survive at higher radiation levels , to operate at higher loads and at higher backgrounds .
the belle @xmath0 and muon system based on the resistive plate chambers ( rpc ) technology worked well during all data taking period , however at belle ii environments its performance decreases to negligible level due to increasing load and high neutron background . to sustain detector operation
it will be replaced by the new system based on the scintillation strips read - out by silicon photomultipliers .
the latter technology allows not only to reach time resolution at level of 1 ns but also perform the amplitude measurements . nowadays
the production of the new eklm system s elements are under way .
the assembly at kek is started this fall . .
And you have already written the first three sentences of the full article: in the constellation of the brilliant elementary particle experiments of the last decades , the b - factories , belle @xcite and babar @xcite , were ones of the most remarkable .
their results on cp - violation in b - mesons prove the validity of the km mechanism , which inventors , m. kobayashi and t. maskawa , won the nobel prize in physics in 2008 .
belle was successful not only in cp - violation studies ..
Please generate the next two sentences of the article | the huge amount of the data collected by the belle detector ( more than one billion @xmath1-pairs ) allows to make a number of discoveries in hadron spectroscopy .
more than 10 new quarkonium - like states were discovered including puzzling x(3872 ) state and new charged z - resonances which do not fit conventional quarkonium model . |
6,708 | Suppose that you have an abstract for a scientific paper: the frequency domain reflectometry ( fdr ) is studied as a powerful tool to detect hard or soft faults in star - shaped networks of nonuniform lossless transmission lines .
processing the fdr measurements leads to solve an inverse scattering problem for a schrdinger operator on a star - shaped graph . throughout this paper
, we restrict ourselves to the case of minimal experimental setup corresponding to only one diagnostic port plug .
first , by studying the asymptotic behavior of the reflection coefficient in the high - frequency limit , we prove the identifiability of the geometry of this star - shaped graph : the number of edges and their lengths .
the proof being rather constructive , it provides a method to detect the hard faults in the network .
next , we study the potential identification problem by inverse scattering , noting that the potentials represent the inhomogeneities due to the soft faults in the network wirings . here , the main result states that the measurement of two reflection coefficients , associated to two different sets of boundary conditions at the extremities of the tree , determines uniquely the potentials ; it is a generalization of the theorem of the two boundary spectra on an interval @xcite .
+ _ inverse scattering , telegrapher s equation , inverse sturm - liouville problem _ .
And you have already written the first three sentences of the full article: the rather extensive literature concerning the `` inverse scattering problem '' and the `` inverse sturm - liouville problem '' on graphs have mostly followed separate pathways except for a very few results @xcite . in the following paragraphs , we briefly recall the previous results on these subjects and at the end we will situate the result of this paper with respect to the others .
indeed , as it will be seen later , the inverse sturm - liouville problem considered in this paper raises from the necessity of finding a minimal setup for solving the inverse scattering problem .
the paper @xcite considers a star - shape graph consisting of @xmath0 infinite branches and solves the inverse scattering problem assuming the measurement of @xmath1 reflection coefficients ..
Please generate the next two sentences of the article | next , in the paper @xcite , harmer provides an extension of the previous result with general self - adjoint boundary conditions at the central node .
this however necessitates the knowledge of @xmath0 reflection coefficients . |
6,709 | Suppose that you have an abstract for a scientific paper: in a recent paper we have suggested that the finite temperature density matrix can be computed efficiently by a combination of polynomial expansion and iterative inversion techniques .
we present here significant improvements over this scheme .
the original complex - valued formalism is turned into a purely real one .
in addition , we use chebyshev polynomials expansion and fast summation techniques .
this drastically reduces the scaling of the algorithm with the width of the hamiltonian spectrum , which is now of the order of the cubic root of such parameter .
this makes our method very competitive for applications to _ ab - initio _
simulations , when high energy resolution is required .
address = computational science , department of chemistry and applied biosciences , eth zurich , usi campus , via giuseppe buffi 13 , ch-6900 lugano , switzerland , , [email protected] address = computational science , department of chemistry and applied biosciences , eth zurich , usi campus , via giuseppe buffi 13 , ch-6900 lugano , switzerland address = computational science , department of chemistry and applied biosciences , eth zurich , usi campus , via giuseppe buffi 13 , ch-6900 lugano , switzerland .
And you have already written the first three sentences of the full article: several fields of computational science ( nanotechnology , materials science or biochemistry just to name a few ) would greatly benefit from the possibility of performing simulations of large systems , containing hundreds of thousands of atoms .
conventional electronic structure calculations require the diagonalization of matrices whose size @xmath0 is of the order of the number of electrons in the system .
the @xmath1-scaling cost of this step greatly limits the range of systems which can be tackled by _.
Please generate the next two sentences of the article | ab - initio _ techniques , despite the fast - paced progress in the computational power of modern processors . based on the theoretical foundations of the nearsightedness principle of electronic matter@xcite ,
several techniques have been developed in the last years to avoid the diagonalization step , by directly computing the density matrix of the system using linear scaling algorithms@xcite . |
6,710 | Suppose that you have an abstract for a scientific paper: we present an investigation of the multiwavelength data on hess j1303 - 631 , an unidentified tev source serendipitously discovered in the galactic plane by the hess collaboration .
our results strongly suggest the identification of this particular source as the remnant of a gamma - ray burst ( grb ) that happened some few tens of thousands years ago in our galaxy at a distance on the order of @xmath0kpc from us .
we show through detailed calculations of particle diffusion , interaction and radiation processes of relativistic particles in the interstellar medium , that it is possible for a grb remnant ( grbr ) to be a strong tev emitter with no observable synchrotron emission .
we predict spectral and spatial signatures that would unambiguously distinguish grbrs from ordinary supernova remnants , including : ( 1 ) large energy budgets inferred from their tev emission , but at the same time ( 2 ) suppressed fluxes in the radio through gev wavebands ; ( 3 ) extended center - filled emission with an energy - dependent spatial profile ; and ( 4 ) a possible elongation in the direction of the past pair of grb jets .
while grbrs can best be detected by ground - based gamma - ray detectors , the future glast mission will play a crucial role in confirming the predicted low level of gev emission . .
And you have already written the first three sentences of the full article: so far , grbs have only been identified at cosmological distances .
it is believed that grbs are caused by highly relativistic outflows with bulk lorentz factors @xmath1 that form a pair of opposite jets . even after correcting for narrow beaming ,
the energy radiated by long - duration ( @xmath2 ) grbs typically is @xmath3 , and the estimated kinetic energy of the jets reaches values of @xmath4 @xcite ..
Please generate the next two sentences of the article | relativistic shocks convert ( accelerate ) _ all _ particles from the incoming plasma they encounter to relativistic energies by randomizing their velocities in the comoving frame . in the stationary frame
the mean energy per particle is @xmath5 @xcite |
6,711 | Suppose that you have an abstract for a scientific paper: we review recent developments in lattice siumulations of the equation of state , order of the thermal phase transition and the determination of the pseudo - critical temperature in ( 2 + 1)-flavor qcd . owing to the increasing computer power , new argothithms , and
improved fermion formulations , studies of bulk qcd matter are approaching to the stage of precision science .
we also review recent lattice studies on the spectral properties of heavy quarkoniums inside the quark - gluon plasma ( qgp ) .
although they are still in an exploratory stage , interesting physics in relation to the strongly correlated qgp is being extracted . .
And you have already written the first three sentences of the full article: a schematic qcd phase diagram in the plane of temperature @xmath0 and baryon chemical potential @xmath1 .
solid lines indicate the first order phase boundaries .
several critical points at which the first order lines terminate may exit , e.g. the high @xmath0 critical point @xcite and high @xmath1 critical point @xcite.,width=302 ] one of the main goals of the lattice qcd studies is to make first principle analysis of hot / dense qcd and to supply reliable inputs to quark - gluon plasma ( qgp ) phenomenologies @xcite ..
Please generate the next two sentences of the article | shown in fig.[t - mu ] is a schematic qcd phase diagram indicating three basic phases ; the chiral symmetry broken ( @xmath2sb ) phase , the color superconducting ( csc ) phase and the qgp phase .
precise locations of the phase boundaries and the critical points as well as the dynamics in each phase should be determined by non - perturbative method such as the lattice qcd . |
6,712 | Suppose that you have an abstract for a scientific paper: following a previous paper on thomson scattering , we present numerical simulations of the periodic polarimetric variations produced by a binary star placed at the center of an empty spherical cavity inside a circumbinary ellipsoidal and optically thin envelope made of dust grains .
mie single - scattering ( on spherical dust grains ) is considered along with pre- and post - scattering extinction factors which produce a time - varying optical depth and affect the morphology of the periodic variations .
the orbits are circular or eccentric .
the mass ratio ( and luminosity ratio ) is equal to 1.0 .
we are interested in the effects that various parameters ( grain characteristics , geometry of the envelope , orbital eccentricity , etc . )
will have on the average polarization , the amplitude of the polarimetric variations , and the morphology of the variability .
we show that the absolute amplitudes of the variations are smaller for mie scattering than for thomson scattering , which makes harder the detection of polarimetric variations for binary stars surrounded by dust grains .
the average polarization produced depends on the grains composition and size , and on the wavelength of observation . among the four grain types that we have studied ( astronomical silicates , graphite , amorphous carbon , and dirty ice ) ,
the highest polarizations are produced by grains with sizes in the range @xmath0@xmath1 ( @xmath2@xmath3 for @xmath4 ) .
composition and size also determine if the polarization will be positive or negative .
in general , the variations are double - periodic ( seen twice per orbit ) . in some cases , because spherical dust grains have an asymmetric scattering function , the polarimetric curves produced show single - periodic variations ( seen once per orbit ) in addition to the double - periodic ones .
a mixture of grains of different sizes does not affect those conclusions .
circumstellar disks produce polarimetric variations of greater amplitude ( up to @xmath5%....
And you have already written the first three sentences of the full article: in the first paper ( manset & bastien 2000 , hereafter referred to as paper i ) , we presented numerical simulations of the periodic polarimetric variations produced by a binary star surrounded by a circumbinary envelope composed of electrons .
thomson scattering was considered in an optically thin situation , along with pre- and post - scattering extinction factors which produce a time - varying ( small ) optical depth and affect the morphology of the periodic variations by adding an additional harmonic to the variations .
we studied the effects that orbital inclination , optical depth , geometry of the envelope and cavity , size and eccentricity of the orbits , and non - equal mass stars had on the average polarization level and the amplitude of the polarimetric variations ..
Please generate the next two sentences of the article | we found that high polarization levels will result from a high inclination , a high optical depth , a flat envelope , or a big central cavity .
polarimetric variations are more apparent for a low inclination , a high optical depth , a flat envelope , a small cavity , or an orbit which brings the stars close to the inner edge of the cavity . using the formalism developed by brown , mclean , & emslie ( 1978 , hereafter bme ) the observations , or in this case the results of the numerical simulations , |
6,713 | Suppose that you have an abstract for a scientific paper: in this paper , we give a natural construction of mixed tate motives whose periods are a class of iterated integrals which include the multiple polylogarithm functions .
given such an iterated integral , we construct two divisors @xmath0 and @xmath1 in the moduli spaces @xmath2 of @xmath3-pointed stable curves of genus @xmath4 , and prove that the cohomology of the pair @xmath5 is a framed mixed tate motive whose period is that integral .
it generalizes the results of a. goncharov and yu .
manin for multiple @xmath6-values
. then we apply our construction to the dilogarithm and calculate the period matrix which turns out to be same with the canonical one of deligne . .
And you have already written the first three sentences of the full article: the multiple polylogarithm functions were defined in goncharov s paper @xcite as the following power series : @xmath7 where the @xmath8 are in the unit disk of the complex plane for @xmath9 and @xmath10 are positive integers . for @xmath11 , we get the classical @xmath3-th polylogarithm which was first introduced by leibniz @xcite in 1696 : @xmath12 and for @xmath13 , we obtain the multiple @xmath6-values which were first studied by euler @xcite : @xmath14 moveover , multiple polylogarithms can be represented as iterated integrals . recall that iterated integrals are defined as follows .
let @xmath15 be smooth one - forms on a manifold @xmath16 and @xmath17 \rightarrow m$ ] be a piecewise smooth path .
then we define inductively as follows : @xmath18 where @xmath19 is the restriction of @xmath20 on @xmath21 $ ] and @xmath22 is a function of @xmath23 on @xmath24 $ ] ..
Please generate the next two sentences of the article | more explicitly , it can be computed in the following way : @xmath25 where @xmath26 are the pullback one - forms on @xmath24 $ ] , @xmath27 .
for example , |
6,714 | Suppose that you have an abstract for a scientific paper: the current paper presents a novel recurrent neural network model , predictive multiple spatio - temporal scales rnn ( p - mstrnn ) , which can generate as well as recognize dynamic visual patterns in a predictive coding framework .
the model is characterized by multiple spatio - temporal scales imposed on neural unit dynamics through which an adequate spatio - temporal hierarchy develops via learning from exemplars .
the model was evaluated by conducting an experiment of learning a set of whole body human movement patterns , which was generated by following a hierarchically defined movement syntax .
the analysis of the trained model clarifies what types of spatio - temporal hierarchy develops in dynamic neural activity as well as how robust generation and recognition of movement patterns can be achieved by using the error minimization principle . .
And you have already written the first three sentences of the full article: predictive coding is a brain plausible principle to account for how diversity of perceptual input sequences can be predicted or generated for different intentions in the top - down pathway as well as how the corresponding intention can be inferred or recognized for a particular observation of perceptual sequence in the bottom - up pathway by using the prediction error minimization principle . within this predictive coding framework
, it has been largely assumed that such prediction / generation and inference / recognition can be conducted through multiple levels across different cortical areas whereas necessary functional hierarchy can be developed via accumulated learning [ 1 , 2 , 3 , 4 ] . the current study examines how a spatio - temporal hierarchy that is adequate for robust generation and recognition of compositional dynamic visual patterns in the pixel level can be developed by proposing a novel deterministic predictive coding type deep recurrent neural network model .
the proposed model , referred to as the predictive multiple spatio - temporal scales rnn ( p - mstrnn ) is a combination of prior - proposed models of the multiple timescales rnn ( mtrnn ) [ 4 ] and the deconvolutional neural network model [ 15 ] where both spatial and temporal multiple scales properties are used as macroscopic constraints to develop an effective functional hierarchy ..
Please generate the next two sentences of the article | there have been prior studies on predicting and generating dynamic visual datasets [ 6 , 7 , 12 , 13 ] . in particular ,
similar to the current paper , lotter et al . in 2016 |
6,715 | Suppose that you have an abstract for a scientific paper: we investigate assortativity of functional brain networks before , during , and after one - hundred epileptic seizures with different anatomical onset locations .
we construct binary functional networks from multi - channel electroencephalographic data recorded from 60 epilepsy patients ; and from time - resolved estimates of the assortativity coefficient we conclude that positive degree - degree correlations are inherent to seizure dynamics . while seizures evolve , an increasing assortativity indicates a segregation of the underlying functional network into groups of brain regions that are only sparsely interconnected , if at all .
interestingly , assortativity decreases already prior to seizure end . together with previous observations of characteristic temporal evolutions of global statistical properties and synchronizability of epileptic brain networks , our findings may help to gain deeper insights into the complicated dynamics underlying generation , propagation , and termination of seizures .
15cm(3cm,26 cm ) copyright ( 2013 ) american institute of physics .
this article may be downloaded for personal use only .
any other use requires prior permission of the author and the american institute of physics .
the article appeared in chaos 23 , 033139 ( 2013 ) and may be found at http://link.aip.org/link/doi/10.1063/1.4821915 doi : 10.1063/1.4821915 _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _....
And you have already written the first three sentences of the full article: complex networks@xcite have been recognized to be powerful representations of complex systems and can advance our understanding of their dynamics .
they are studied in diverse disciplines ranging from earth@xcite and climate science@xcite to the neurosciences@xcite . in this perspective
, systems are considered to be composed of subsystems ( i.e. , nodes ) which can or can not interact with each other according to some underlying physical coupling topology ( represented by links between nodes ) . while such structural networks have been studied extensively and.
Please generate the next two sentences of the article | are considered to serve as the physical substrate on which dynamical patterns can emerge , it is only recently that research into network dynamics gained strong momentum@xcite .
the system dynamics may be represented by an interaction ( or functional ) network in which nodes represent subsystems and links reflect interactions between them . in field studies , such networks are usually derived via time series analysis techniques where nodes are associated with sensors and links are derived from the strength and/or direction of interactions as assessed by estimators of signal interdependence@xcite . using concepts from network theory , |
6,716 | Suppose that you have an abstract for a scientific paper: we demonstrate a simple technique to measure the resonant frequency of the 398.9 nm @xmath0 transition for the different yb isotopes .
the technique , that works by observing and aligning fluorescence spots , has enabled us to measure transition frequencies and isotope shifts with an accuracy of 60 mhz .
we provide wavelength measurements for the transition that differ from previously published work .
our technique also allows for the determination of doppler shifted transition frequencies for photoionisation experiments when the atomic beam and laser beam are not perpendicular and furthermore allows us to determine the average velocity of the atoms along the direction of atomic beam . .
And you have already written the first three sentences of the full article: ytterbium , both atomic and singly ionised , is an element widely used in experiments involving trapped atoms and ions , such as laser cooling and trapping of neutral atoms and ions @xcite , atomic clocks @xcite , frequency standards @xcite , quantum computing experiments @xcite , quantum optics @xcite and atomic parity non - conservation experiments @xcite .
knowledge of the @xmath1 transition line in atomic yb and corresponding frequency shifts for the stable isotopes is very important in these experiments as they allow for laser cooling and isotope selective photoionisation @xcite .
various methods have been used to investigate these transitions , and corresponding isotope shifts @xcite ..
Please generate the next two sentences of the article | + we present our measurements of the ytterbium @xmath0 transition frequencies which differ from previously published results @xcite . using a simple method based upon observing and aligning fluorescence spots of atomic yb generated from an atomic oven in an evacuated glass beljar
we have measured resonant transition frequencies and isotope shifts to an accuracy of 60 mhz . |
6,717 | Suppose that you have an abstract for a scientific paper: in this paper we study the scalar and electromagnetic perturbations of an extended black hole in f(r ) gravity .
the quasinormal modes in two cases are evaluated and studied their behavior by plotting graphs in each case . to study the quasinormal mode , we use the third order wkb method .
the present study shows that the absolute value of imaginary part of complex quasinormal modes increases in both cases , thus the black hole is stable against these perturbations . as the mass of the scalar field increases the imaginary part of the frequency decreases .
thus damping slows down with increasing mass of the scalar field . .
And you have already written the first three sentences of the full article: one of the most exciting discoveries in cosmology after hubble s discovery of expansion of universe is the accelerated expansion of the universe@xcite . in order to explain the acceleration
, it becomes necessary to modify the existing theory of gravitation proposed by einstein , ie .
, the general theory of relativity ..
Please generate the next two sentences of the article | it can be done in two ways , the first one is to modifying the energy - momentum part of the field equation .
this necessitates the existence of an exotic component called dark energy . |
6,718 | Suppose that you have an abstract for a scientific paper: methods of borel integration to calculate the binding ground energies and mass of @xmath0 quarkonia are presented .
the methods take into account the leading infrared renormalon structure of the `` soft '' binding energy @xmath1 and of the quark pole masses @xmath2 , and the property that the contributions of these singularities in @xmath3 cancel .
the resummation formalisms are applied to quantities which do not involve renormalon ambiguity , such as @xmath4 mass @xmath5 and @xmath6 . .
And you have already written the first three sentences of the full article: the calculation of binding energies , masses of heavy quarkonia @xmath7 and another physical parameter using renormalon method has attracted the attention recently .
the calculations , based on perturbative expansions , are primarily due to the knowledge of up to @xmath8 term ( @xmath9 ) of the static quark - antiquark potential @xmath10 @xcite and partial knowledge of the @xmath11 term there , and the ultrasoft gluon contributions to a corresponding effective theory @xmath11 hamiltonian @xcite ; and the knowledge of the pole mass @xmath2 up to order @xmath12 @xcite .
another impetus in these calculations was given by the observation of the fact that the contributions of the leading infrared ( ir ) renormalon singularities ( at @xmath13 ) of the pole mass @xmath2 and of the static potential @xmath10 cancel in the sum @xmath14 @xcite ..
Please generate the next two sentences of the article | consequently , this cancellation effect must be present also in the total quarkonium mass @xmath15 @xcite , or more precisely , in @xmath3 where @xmath1 is the hard@xmath16soft part of the binding energy , i.e. , the part which includes the contributions of relative quark - antiquark momenta @xmath17 , @xmath18 , i.e. , soft / potential scales ( predominant ) and higher hard scales ( smaller contributions ) .
in addition , the binding energy has contribution @xmath19 from the ultrasoft momenta regime @xmath17 , @xmath20 . |
6,719 | Suppose that you have an abstract for a scientific paper: -6.5 cm fermilab - conf-01/010-t 0.25 cm hep - ph/0102029 5.7 cm in the minimal supersymmetric extension of the standard model ( mssm ) , fermion masses and yukawa couplings receive radiative corrections at one loop from diagrams involving the supersymmetric particles .
the corrections to the relation between down - type fermion masses and yukawa couplings are enhanced by @xmath0 , which makes them potentially very significant at large @xmath0 .
these corrections affect a wide range of processes in the mssm , including neutral and charged higgs phenomenology , rare @xmath1 meson decays , and renormalization of the ckm matrix . we give a pedagogical review of the sources and phenomenological effects of these corrections . .
And you have already written the first three sentences of the full article: in the minimal supersymmetric extension of the standard model ( mssm ) @xcite , radiative corrections involving supersymmetric ( susy ) particles modify the tree level relation between fermion masses and their yukawa couplings @xcite . in this paper
we review the sources and behavior of these susy yukawa corrections and describe their phenomenological effects .
the behavior of the susy yukawa corrections is most easily derived in the context of an effective field theory ( eft ) , in which we take the low energy effective theory of the mssm below the susy scale to be a two higgs doublet model ( 2hdm ) and absorb the effects of susy radiative corrections into the parameters of the eft . at tree level , the fermion yukawa couplings and masses arise from the lagrangian , @xmath2 + { \rm h.c . } \ ] ] where we use third generation quark notation and the higgs doublets are @xmath3 the higgs vacuum expectation values ( vevs ) are constrained by @xmath4 and their ratio is parameterized by @xmath5 ..
Please generate the next two sentences of the article | the fermion masses arise from replacing the higgs fields with their vevs : @xmath6 so that @xmath7 and @xmath8 . at tree level ,
down - type fermions receive their masses from @xmath9 while up - type fermions receive their masses from @xmath10 . |
6,720 | Suppose that you have an abstract for a scientific paper: in the present work , we propose a new set of coherent structures that arise in nonlinear dynamical lattices with more than one components , namely interlaced solitons .
these are waveforms in which in the relevant anti - continuum limit , i.e. when the sites are uncoupled , one component has support where the other component does not .
we illustrate systematically how one can combine dynamically stable unary patterns to create ones such for the binary case of two - components . in the one - dimensional setting ,
we provide also a detailed theoretical analysis of the existence and stability of these waveforms , while in higher dimensions , where such analytical computations are far more involved , we resort to corresponding numerical computations .
lastly , we perform direct numerical simulations to showcase how these structures break up , when exponentially or oscillatorily unstable , to structures with a smaller number of participating sites . .
And you have already written the first three sentences of the full article: one of the highly active areas of investigation of hamiltonian nonlinear systems over the past decade has been the examination of nonlinear dynamical lattices of the discrete nonlinear schrdinger ( dnls ) type .
chiefly , this development has arisen due to the multitude of applications of pertinent models that have emerged in areas such as nonlinear optics and atomic physics .
more specifically , in the optical context , the setting of fabricated algaas waveguide arrays @xcite has been one of the most prototypical ones for the application of dnls models ..
Please generate the next two sentences of the article | there , the interplay of discreteness and nonlinearity revealed many interesting features including peierls - nabarro potential barriers , diffraction and diffraction management @xcite , and gap solitons @xcite , among others ; see also the reviews @xcite and references therein .
another recent development , which also promoted the analysis of discrete systems in connection with nonlinear optics was the proposal @xcite and creation @xcite of optically induced photonic lattices in photorefractive crystals such as sbn . |
6,721 | Suppose that you have an abstract for a scientific paper: three models of a flat universe of coupled matter and dark energies with different low - redshift parameterizations of the dark energy equation of state are considered .
the dark energy is assumed to vary with time like the trace of the energy - momentum tensor of cosmic matter . in the radiation - dominated era
the models reduce to standard cosmology . in the matter - dominated era they are , for modern values of the cosmological parameters , consistent with data from sne ia searches and with the data of @xcite for angular sizes of ultra compact radio sources .
we find that the angular size - redshift tests for our models offer a higher statistical confidence than that based on sne ia data .
a comparison of our results with a recent revised analysis of angular size - redshift legacy data is made , and the implications of our models with optimized relativistic beaming in the radio sources is discussed .
in particular we find that relativistic beaming implies a lorentz factor less than 6,in agreement with its values for powerful active galactic nuclei . .
And you have already written the first three sentences of the full article: there is now substantial observational evidence@xcite that favors the existence of a smooth exotic cosmic component of energy of negative pressure .
going at times under the name of a cosmological constant or quintessence or , at other times , dark energy , which we will adopt here , its true nature remains obscure .
the unexpected faintness of high redshift type ia supernovae ( sne ia)suggests that the universe is accelerating today@xcite , relentlessly driven by dark energy . when the sne ia results are combined with observations of the amplitudes of primordial fluctuations in the cosmic microwave background radiation the overall picture seems to be one of an accelerating flat universe ..
Please generate the next two sentences of the article | since the standard flat universe , despite its well - known shortcomings , has long been favored on aesthetic and theoretical grounds@xcite , the hope has arisen that the injection of dark energy will cure its ills , particularly in regards of its age of the universe problem .
thus a major industry of investigating the constraints imposed by continuously updated astrophysical observations on the dark energy in refined versions of the standard model has flourished in recent times . |
6,722 | Suppose that you have an abstract for a scientific paper: a generalization of the gram - schmidt procedure is achieved by providing equations for updating and downdating oblique projectors .
the work is motivated by the problem of adaptive signal representation outside the orthogonal basis setting .
the proposed techniques are shown to be relevant to the problem of discriminating signals produced by different phenomena when the order of the signal model needs to be adjusted .
= 1 .
And you have already written the first three sentences of the full article: an operator @xmath0 is a projector if it is idempotent , i.e. , if it is endowed with property @xmath1 .
the projection is along ( or parallel to ) its null space @xmath2 and onto its range @xmath3 .
this entails that @xmath4 for @xmath5 and @xmath6 for @xmath7 ..
Please generate the next two sentences of the article | if the subspaces @xmath3 and @xmath2 are orthogonal the operator is called an orthogonal projector , which is the case if and only if @xmath0 is self - adjoint .
otherwise it is called oblique projector . |
6,723 | Suppose that you have an abstract for a scientific paper: there is growing evidence from both spectral and timing properties that there is a truncated inner accretion disc in low mass accretion rate galactic black hole systems .
the detection of _ extremely _ smeared relativistic iron lines in some of these systems is the _ only _ current piece of evidence which conflicts with this geometrical interpretation of the low / hard state .
here we show that the line width in the _ bepposax _ data of a bright low / hard state of the transient black hole xte j1650500 is indeed consistent with extreme relativistic effects . however , the relativistic smearing can be _ significantly _ reduced if there is also resonance iron k line _ absorption _ from an outflowing disc wind .
the iron line smearing is then completely compatible with a truncated disc , so gives no information on the black hole spin .
= -0.5 cm [ firstpage ] accretion , accretion discs black hole physics
x - rays : binaries x - rays : individual : xte j1650 - 500 .
And you have already written the first three sentences of the full article: the existence of a minimum stable orbit for material around a black hole is a key prediction of general relativity in the strong field limit . for schwarzschild black holes
this is at @xmath0 ( where @xmath1 ) , while for maximally rotating kerr black holes ( spin parameter @xmath2 ) this reduces to @xmath3 .
bright accretion flows give a way to observationally test such ideas as well as to directly estimate the spin of the black hole ..
Please generate the next two sentences of the article | optically thick material in keplerian orbits should emit a quasi - thermal spectrum with maximum temperature emission from the largest luminosity / smallest area regions i.e. set by the last stable orbit ( shakura & sunyaev 1973 ) .
as these models are thermal , there is a clear prediction that their maximum temperature , @xmath4 , should increase with total disc luminosity as @xmath5 , if the emission is from a constant area i.e. if there is a constant inner disc radius . |
6,724 | Suppose that you have an abstract for a scientific paper: a monte carlo simulation exploring uncertainties in standard stellar evolution theory on the red giant branch of metal - poor globular clusters has been conducted .
confidence limits are derived on the absolute @xmath0-band magnitude of the bump in the red giant branch luminosity function ( ) and the excess number of stars in the bump , .
the analysis takes into account uncertainties in the primordial helium abundance , abundance of alpha - capture elements , radiative and conductive opacities , nuclear reaction rates , neutrino energy losses , the treatments of diffusion and convection , the surface boundary conditions , and color transformations .
the uncertainty in theoretical values for the red giant bump magnitude varies with metallicity between @xmath1 mag at @xmath2$}}= -2.4 $ ] and @xmath3 mag at @xmath2$}}= -1.0 $ ] .
the dominant sources of uncertainty are the abundance of the alpha - capture elements , the mixing length , and the low - temperature opacities .
the theoretical values of are in good agreement with observations .
the uncertainty in the theoretical value of is @xmath4 at all metallicities studied .
the dominant sources of uncertainty are the abundance of the alpha - capture elements , the mixing length , and the high - temperature opacities .
the median value of varies from 0.44 at @xmath2$}}= -2.4 $ ] to @xmath5 at @xmath2$}}= -1.0 $ ] .
these theoretical values for are in agreement with observations . .
And you have already written the first three sentences of the full article: globular clusters are made up of a very large number of stars with varying mass but identical age , composition , and distance .
this makes them a rich and productive application of the theory of stellar structure and evolution .
detailed stellar evolution calculations are done numerically using computer programs which incorporate previously calculated nuclear reaction rates and opacities , approximations to complex phenomena such as convection , and assumptions about the chemical composition . to compare theoretical models to observations ,.
Please generate the next two sentences of the article | moreover , requires converting physical quantities such as luminosity and surface temperature to the observational system of magnitudes and colors using empirical relations or the results of separate stellar atmosphere models .
the results of theoretical stellar evolution calculations , therefore , depend upon a set of prior assumptions . to assess the reliability of theoretical models of globular clusters stars one must study how uncertainties in these assumptions of stellar evolution theory propagate to the predictions of the theory . in this work |
6,725 | Suppose that you have an abstract for a scientific paper: within leading - order perturbation theory , the casimir - polder potential of a ground - state atom placed within an arbitrary arrangement of dispersing and absorbing linear bodies can be expressed in terms of the polarizability of the atom and the scattering green tensor of the body - assisted electromagnetic field . based on a born series of the green tensor , a systematic expansion of the casimir - polder potential in powers of the electric susceptibilities of the bodies is presented .
the born expansion is used to show how and under which conditions the casimir - polder force can be related to microscopic many - atom van der waals forces , for which general expressions are presented . as an application ,
the casimir - polder potentials of an atom near a dielectric ring and an inhomogeneous dielectric half space are studied and explicit expressions are presented that are valid up to second order in the susceptibility . *
pacs * 12.20.-m quantum electrodynamics
34.50.dy interactions of atoms and molecules with surfaces ; photon and electron emission ; neutralization of ions 34.20.-b interatomic and intermolecular potentials and forces , potential energy surfaces for collisions 42.50.nn quantum optical phenomena in absorbing , dispersive and conducting media .
And you have already written the first three sentences of the full article: the forces of electromagnetic origin that arise between electrically neutral , unpolarized but polarizable objects are commonly known as dispersion forces @xcite .
they were first addressed within the context of quantum electrodynamics ( qed ) by casimir and polder @xcite , who showed that they may be attributed to the vacuum fluctuations of the electromagnetic field . in accordance with the different nature of the interacting objects
, one may distinguish between three types of dispersion forces , namely the forces between atoms in the following referred to as van der waals ( vdw ) forces , the forces between atoms and macroscopic bodies in the following referred to as casimir - polder ( cp ) forces , and the forces between macroscopic bodies in the following referred to as casimir forces ..
Please generate the next two sentences of the article | dispersion forces play a major role in the understanding of many phenomena , and they can be a useful or disturbing factor in modern applications . apart from being crucial for the understanding of many structures and processes in biochemistry @xcite ,
they are responsible for the remarkable climbing skills of some gecko @xcite and spider species @xcite ; the construction of atomic - force microscopes is essentially based on dispersion forces @xcite , while they are also responsible for the problem of sticking in nanotechnology @xcite . in particular , |
6,726 | Suppose that you have an abstract for a scientific paper: a long - lasting debate in space plasma physics concerns the nature of subproton - scale fluctuations in solar wind ( sw ) turbulence . over the past decade ,
a series of theoretical and observational studies were presented in favor of either kinetic alfvn wave ( kaw ) or whistler turbulence . here
, we investigate numerically the nature of the subproton - scale turbulent cascade for typical sw parameters by means of unprecedented high - resolution simulations of forced hybrid - kinetic turbulence in two real - space and three velocity - space dimensions .
our analysis suggests that small - scale turbulence in this model is dominated by kaws at @xmath0 and by magnetosonic / whistler fluctuations at lower @xmath1 .
the spectral properties of the turbulence appear to be in good agreement with theoretical predictions . a tentative interpretation of this result in terms of relative changes in the damping rates of the different waves is also presented .
overall , the results raise interesting new questions about the properties and variability of subproton - scale turbulence in the sw , including its possible dependence on the plasma @xmath1 , and call for detailed and extensive parametric explorations of driven kinetic turbulence in three dimensions . .
And you have already written the first three sentences of the full article: the solar wind ( sw ) plasma , an ideal laboratory for the study of collisionless plasma dynamics , is mostly found in a turbulent state @xcite .
subproton - scale ( `` dissipation range '' ) turbulence in the sw has become a major research topic over the past decade , both for in - situ satellite measurements @xcite and for numerical @xcite and theoretical @xcite studies .
spacecraft observations provide important constraints on turbulent spectra , revealing the presence of breaks in the electromagnetic fluctuations around the proton kinetic scales @xcite . at subproton scales , typical slopes for the magnetic energy spectrum are found to be in the range @xmath2 $ ] , while preliminary results about its electric counterparts are in the range @xmath3 $ ] . from a theoretical point of view , possible explanations for the observed spectra are the development of a kinetic alfvn wave ( kaw ) cascade and/or a whistler cascade @xcite ..
Please generate the next two sentences of the article | however , the predicted energy spectra are the same for the two cases and thus auxiliary methods have been suggested in order to identify the exact nature of turbulent fluctuations @xcite .
observational evidence points towards a kaw - dominated scenario for a @xmath4 plasma @xcite ( @xmath1 is the ratio between the thermal and the magnetic pressures ) , although contradictory results have also been reported @xcite . |
6,727 | Suppose that you have an abstract for a scientific paper: we present an improved method for predicting the sunyaev - zeldovich ( sz ) effect in galaxy clusters from spatially - resolved , spectroscopic x - ray data . using the deprojected electron density and temperature profiles measured within a fraction of the virial radius , and assuming a @xcite mass model ,
we show how the pressure profile of the x - ray gas can be extrapolated to large radii , allowing the comptonization parameter profile for the cluster to be predicted precisely .
we apply our method to chandra observations of three x - ray luminous , dynamically relaxed clusters with published sz data : rx j1347.5 - 1145 , abell 1835 and abell 478 . combining the predicted and observed sz signals , we determine improved estimates for the hubble constant from each cluster and obtain a weighted mean of @xmath0 for a cosmology with @xmath1 and @xmath2 .
this result is in good agreement with independent findings from the hubble key project and the combination of cosmic microwave background and galaxy cluster data .
[ firstpage ] x - rays : galaxies : clusters cosmic microwave background
cosmology : observations distance scale galaxies : clusters : individual ( rx j1347.5 - 1145 , abell 1835 , abell 478 ) .
And you have already written the first three sentences of the full article: the inverse compton scattering of cosmic microwave background ( cmb ) photons by hot electrons in galaxy clusters leads to a distortion of the cmb spectrum along the line of sight , known as the sunyaev - zeldovich ( sz , @xcite ) effect .
the magnitude of the sz effect is determined by the comptonization parameter of the cluster gas , @xmath3 , which is proportional to the line of sight integral of the gas pressure .
it was recognized swiftly @xcite that for an assumed , simple geometry , the combination of x - ray and sz observations can be used to measure the angular diameter distance to a cluster . the ratio of the observed ( based on radio / sub - mm observations ) and predicted ( based on x - ray observations ) sz signals is proportional to the square of the angular diameter distance , making this , potentially , an exceptionally powerful technique for probing the cosmic distance scale . although the sz effect is now employed frequently to determine extragalactic distances ( e.g. , * ? ? ?.
Please generate the next two sentences of the article | * ; * ? ? ?
* ; * ? ? ? |
6,728 | Suppose that you have an abstract for a scientific paper: we find a transformation which relates a new third - order integrable nonlinear evolution equation , introduced recently by qiao , with the well - known modified korteweg de vries equation .
then we use this transformation to derive smooth soliton solutions of the new equation from the known rational and soliton solutions of the old one . .
And you have already written the first three sentences of the full article: in the present paper , we study the following third - order integrable nonlinear evolution equation : @xmath0 this equation was introduced recently by qiao @xcite as the second positive member in a new completely integrable hierarchy . the qiao equation
we will refer to in this way possesses a lax representation and a bi - hamiltonian structure @xcite .
moreover , the qiao equation may be reduced from the two - dimensional euler equation by an approximation procedure , and its solutions may be useful to construct new solvable potentials in newtonian dynamics and to model electrophysiological phenomena in neuroscience @xcite ..
Please generate the next two sentences of the article | there is an interesting problem concerning the soliton solution of the qiao equation . in @xcite , where the traveling wave solutions of were studied ,
it was stated that this equation has no smooth solitons , and only piecewise smooth , but not smooth , continuous traveling wave solutions were found in those papers . on the other hand , in @xcite , where the bifurcations of traveling wave solutions of were studied , |
6,729 | Suppose that you have an abstract for a scientific paper: we construct families of symmetric , antisymmetric , and asymmetric solitary modes in one - dimensional bichromatic lattices with the second - harmonic - generating ( @xmath0 ) nonlinearity concentrated at a pair of sites placed at distance @xmath1 .
the lattice can be built as an array of optical waveguides .
solutions are obtained in an implicit analytical form , which is made explicit in the case of adjacent nonlinear sites , @xmath2 .
the stability is analyzed through the computation of eigenvalues for small perturbations , and verified by direct simulations . in the cascading limit , which corresponds to large mismatch @xmath3 ,
the system becomes tantamount to the recently studied single - component lattice with two embedded sites carrying the cubic nonlinearity .
the modes undergo qualitative changes with the variation of @xmath3 . in particular , at @xmath4 , the symmetry - breaking bifurcation ( sbb ) , which creates asymmetric states from symmetric ones , is supercritical and subcritical for small and large values of @xmath3 , respectively , while the bifurcation is always supercritical at @xmath2 . in the experiment ,
the corresponding change of the phase transition between the second and first kinds may be implemented by varying the mismatch , via the wavelength of the input beam .
the existence threshold ( minimum total power ) for the symmetric modes vanishes exactly at @xmath5 , which suggests a possibility to create the solitary mode using low - power beams .
the stability of solution families also changes with @xmath3 . .
And you have already written the first three sentences of the full article: the structure of bound states in linear systems follows the symmetry of the underlying potential , a commonly known example being wave functions of eigenstates in symmetric double - well potentials @xcite .
the addition of the self - attractive nonlinearity leads to a qualitative change of the situation , causing the transition from the symmetric ground state to an asymmetric one , if the strength of the nonlinearity exceeds a critical value @xcite .
this transition was studied in detail for bose - einstein condensates ( becs ) loaded into double - well potentials @xcite ..
Please generate the next two sentences of the article | experimentally , the transition was realized in bec @xcite and in nonlinear optics , where a double - well structure was induced in a photorefractive material @xcite .
the limit case of the double - well setting with a tall potential barrier between the wells corresponds to the _ dual - core _ system , such as optical fibers @xcite and bragg gratings @xcite with the twin - core structure , and pairs of linearly coupled planar waveguides with the @xmath0 ( second - harmonic - generating ) intrinsic nonlinearity mak - chi2 . |
6,730 | Suppose that you have an abstract for a scientific paper: we investigate the photometric properties of the early type brightest cluster galaxies ( bcgs ) using a carefully selected sample of 85 bcgs from the c4 cluster catalogue with redshift less than 0.1 .
we perform accurate background subtractions , and surface photometry for these bcgs to 25 @xmath0 in the sloan @xmath1-band . by quantitatively analysing the gradient of the petrosian profiles of bcgs
, we find that a large fraction of bcgs have extended stellar envelopes in their outskirts ; more luminous bcgs tend to have more extended stellar halos that are likely connected with mergers .
a comparison sample of elliptical galaxies was chosen with similar apparent magnitude and redshift ranges , for which the same photometric analysis procedure is applied .
we find that bcgs have steeper size - luminosity ( @xmath2 ) and faber - jackson ( @xmath3 ) relations than the bulk of early type galaxies .
furthermore , the power - law indices ( @xmath4 and @xmath5 ) in these relations increase as the isophotal limits become deeper . for isophotal limits from 22 to 25 @xmath0 , bcgs are usually larger than the bulk of early type galaxies , and a large fraction ( @xmath6 ) of bcgs have disky isophotal shapes .
the differences in the scaling relations are consistent with a scenario where the dynamical structure and formation route of bcgs may be different from the bulk of early type galaxies , in particular dry ( dissipationless ) mergers may play a more important role in their formation ; we highlight several possible dry merger candidates in our sample .
[ firstpage ] galaxies : e / s0s galaxies : cd galaxies : cluster of galaxies galaxies : photometry galaxies .
And you have already written the first three sentences of the full article: the brightest cluster galaxies ( bcgs ) are the most luminous and most massive galaxies in the universe .
bcgs are located close to the centre of the clusters of galaxies based on the x - ray observations or gravitational lensing observations ( e.g. , jones & forman 1984 ; smith et al .
it was noted very early on that some bcgs show an excess of light ( ` envelopes ' ) over the de vaucouleurs ( @xmath7 ) profile at large radii ( matthews et al ..
Please generate the next two sentences of the article | 1964 ; oemler 1973 , 1976 ; schombert 1986 , 1987 , 1988 ; graham et al .
1996 ) , and a large fraction of bcgs are termed as cd galaxies ( e.g. , patel et al . |
6,731 | Suppose that you have an abstract for a scientific paper: phenix has extended the measurement of the @xmath0 , @xmath1 , identified and inclusive charged hadron up to 20 gev / c , and extended the measurement to the cu+cu collision system .
a strong suppression is observed for both @xmath0 and charged hadron yields in central au+au and cu+cu collisions . comparing au+au and cu+cu systems
, @xmath2 becomes independent of @xmath3 above 5 gev / c .
its centrality dependence is compared with two models in order to test for universal @xmath4 scaling that is independent of system ; results are inconclusive .
the results are compatible with energy loss predictions .
in addition , the ratio of @xmath1 to @xmath0 approaches , within uncertainties , a constant value of @xmath5 at high @xmath3 in p+p , d+au , and au+au , while the ratio of @xmath6 to @xmath0 is also consistent with a constant value at high @xmath3 in d+au and p+p . these results are compatible with normal jet fragmentation . .
And you have already written the first three sentences of the full article: we have previously observed that @xmath0 , @xmath1 and charged hadron yields are significantly suppressed especially for the high @xmath3 region ( @xmath3 @xmath7 @xmath8 gev / c ) in au+au collision at 200 gev compared with p+p collisions.@xcite@xcite@xcite@xcite since there is no suppression in d+au collisions at high @xmath3,@xcite it is understood that the suppression occurs due to the final state interaction at the collision such as the gluon radiation in the hot dense matter .
another evidence for the suppression being a final state effect comes from the non - suppression of the direct photon yield in au+au collisions.@xcite to understand the character of the suppression more , the comparison between different system size ( p+p / d+au / cu+cu / au+au ) measurements has been studied , and an extended @xmath3 reach to 20 gev / c has been afforded by the long run4 au+au dataset .
we newly measured the following spectra ..
Please generate the next two sentences of the article | * @xmath0 spectra with extended @xmath3 range in au+au at 200gev * @xmath0 and charged hadron spectra in cu+cu at 200gev * @xmath6 spectra in d+au and p+p at 200gev @xcite * newly finalized @xmath1 spectra in p+p , d+au , and au+au @xcite the phenix experiment consists of four spectrometer arms ( two central arms and two muon arms ) and a set of global detectors .
each central arm covers the pseudorapidity range @xmath9 @xmath1 @xmath9 @xmath10 @xmath11 and 90 degrees in azimuth . |
6,732 | Suppose that you have an abstract for a scientific paper: a number of different families of nanowires which self - assemble on semiconductor surfaces have been identified in recent years .
they are particularly interesting from the standpoint of nanoelectronics , which seeks non - lithographic ways of creating interconnects at the nanometre scale ( though possibly for carrying signal rather than current ) , as well as from the standpoint of traditional materials science and surface science .
we survey these families and consider their physical and electronic structure , as well as their formation and reactivity .
particular attention is paid to rare earth nanowires and the bi nanoline , both of which self - assemble on si(001 ) . .
And you have already written the first three sentences of the full article: as the scale of architectures in integrated circuit design continues to be reduced , the dimensions of present - day interconnects are on the scale of tens of nanometers , and the interconnects for next - generation nanoelectronic devices may well be just a few nanometers in lateral dimension .
furthermore , the incorporation of nanometer - scale components , such as active molecules , into integrated circuits will require interconnects of a similar scale . on these scales ,
self - assembled nanowire systems are becoming increasingly interesting@xcite , as conventional lithographic techniques reach their limits around 10 - 15nm@xcite and spm - based nanolithography@xcite methods lack scalability . moreover , the introduction of such `` bottom - up '' technology , based on naturally nanometer - scale components to complement or even replace the current `` top - down '' technology is likely to require completely different architectures ..
Please generate the next two sentences of the article | one example is the `` crossbar '' architecture@xcite , in which active molecules are used as devices at the junctions between two perpendicular nanowires .
this architecture is designed to take advantage of the typical product of self - assembly schemes an array of parallel wires rather than relying on controlled positioning of individual wires . |
6,733 | Suppose that you have an abstract for a scientific paper: we analyze the impact of _ fermi _ gamma - ray observations ( primarily non - detections ) of selected nearby galaxies , including dwarf spheroidals , and of clusters of galaxies on decaying dark matter models .
we show that the fact that galaxy clusters do not shine in gamma rays puts the most stringent limits available to - date on the lifetime of dark matter particles for a wide range of particle masses and decay final states .
in particular , our results put strong constraints on the possibility of ascribing to decaying dark matter both the increasing positron fraction reported by pamela and the high - energy feature in the electron - positron spectrum measured by _
fermi_. observations of nearby dwarf galaxies and of the andromeda galaxy ( m31 ) do not provide as strong limits as those from galaxy clusters , while still improving on previous constraints in some cases . .
And you have already written the first three sentences of the full article: a large variety of independent astronomical observations have revealed that most of the mass in the universe is some form of non - baryonic , non - luminous , cold dark matter of as yet unknown composition .
understanding the fundamental nature of dark matter is one of the biggest outstanding problems in cosmology and particle physics ( for a comprehensive review , see e.g. * ? ? ?
compelling particle candidates for the dark matter , collectively termed weakly interacting massive particles ( wimps ) , exist in several well - motivated theoretical extensions of the standard model of particle physics like supersymmetry ( lightest supersymmetric particle , for a review see e.g. * ? ? ? * ) and universal extra dimensions ( lightest kaluza - klein particle , for a review see e.g. * ? ? ? * ) . a signal from dark matter could be detected in astronomical observations from wimp pair annihilation or decay ..
Please generate the next two sentences of the article | for example , wimp annihilation or decay generically leads to the production of gamma - rays ( as well as of other high energy particles ) , potentially at a detectable level with current telescopes @xcite .
the unparalleled sensitivity of the _ fermi _ large area telescope ( lat ) at gev energies makes it an excellent instrument to look for this gamma - ray signal ( e.g. * ? ? ? |
6,734 | Suppose that you have an abstract for a scientific paper: this paper studies maximum likelihood(ml ) decoding in error - correcting codes as rational maps and proposes an approximate ml decoding rule by using a taylor expansion .
the point for the taylor expansion , which will be denoted by @xmath0 in the paper , is properly chosen by considering some dynamical system properties .
we have two results about this approximate ml decoding .
the first result proves that the order of the first nonlinear terms in the taylor expansion is determined by the minimum distance of its dual code . as the second result
, we give numerical results on bit error probabilities for the approximate ml decoding .
these numerical results show better performance than that of bch codes , and indicate that this proposed method approximates the original ml decoding very well .
maximum likelihood decoding , rational map , dynamical system + * ams subject classification .
* 37n99 , 94b35 .
And you have already written the first three sentences of the full article: this paper proposes a new perspective to maximum likelihood(ml ) decoding in error - correcting codes as rational maps and shows some relationships between coding theory and dynamical systems . in section [ sec : cs ] , [ sec : lc ] , and [ sec : ml ] , we explain notations and minimum prerequisites of coding theory ( e.g. , see @xcite ) .
the main results are presented in section [ sec : result ] .
a mathematical model of communication systems in information theory was developed by shannon @xcite . a general block diagram for visualizing the behavior of such systems.
Please generate the next two sentences of the article | is given by figure [ fig : channel ] .
the source transmits a @xmath1-bit message @xmath2 to the destination via the channel , which is usually affected by noise @xmath3 . in order to recover the transmitted message at the destination under the influence of noise |
6,735 | Suppose that you have an abstract for a scientific paper: information entropy has been proved to be an effective tool to quantify the structural importance of complex networks . in the previous work ( xu et al , 2016 @xcite )
, we measure the contribution of a path in link prediction with information entropy . in this paper
, we further quantify the contribution of a path with both path entropy and path weight , and propose a weighted prediction index based on the contributions of paths , namely weighted path entropy ( wpe ) , to improve the prediction accuracy in weighted networks .
empirical experiments on six weighted real - world networks show that wpe achieves higher prediction accuracy than three typical weighted indices .
link prediction , weighted networks , information entropy 89.75.hc , 89.75.fb , 89.20.hh .
And you have already written the first three sentences of the full article: in the field of network science , real - world complex systems are abstracted as complex networks , in which nodes represent individuals and links denote the connections or interactions between individuals @xcite . nowadays ,
although we can obtain abundant data of various complex systems due to advanced technologies , it is demonstrated that larger parts of the data of the complex systems are still not available , and there are non - ignorable errors in the data that we obtain @xcite .
thus , new methods are needed to process , correct , and make predictions from the data ..
Please generate the next two sentences of the article | link prediction methods aim to predict the missing or future links among network data @xcite .
specifically , they estimate the existence likelihood of links between two nodes based on observed links and nodes attributes . |
6,736 | Suppose that you have an abstract for a scientific paper: we present a theoretical model for the thermal x - ray emission properties and cooling behaviors of isolated pulsars , assuming that pulsars are solid quark stars .
we calculate the heat capacity for such a quark star , including the component of the crystalline lattice and that of the extremely relativistic electron gas .
the results show that the residual thermal energy can not sustain the observed thermal x - ray luminosities seen in typical isolated x - ray pulsars .
we conclude that other heating mechanisms must be in operation if the pulsars are in fact solid quark stars .
two possible heating mechanisms are explored .
firstly , for pulsars with little magnetospheric activities , accretion from the interstellar medium or from the material in the associated supernova remnants may power the observed thermal emission . in the propeller regime
, a disk - accretion rate @xmath01 % of the eddington rate with an accretion onto the stellar surface at a rate of @xmath1 could explain the observed emission luminosities of the dim isolated neutron stars and the central compact objects .
secondly , for pulsars with significant magnetospheric activities , the pulsar spindown luminosities may have been as the sources of the thermal energy via reversing plasma current flows . a phenomenological study between pulsar bolometric x - ray luminosities and the spin energy loss rates
presents the probable existence of a 1/2-law or a linear law , i.e. @xmath2 or @xmath3 .
this result together with the thermal properties of solid quark stars allow us to calculate the thermal evolution of such stars .
thermal evolution curves , or cooling curves , are calculated and compared with the ` temperature - age ' data obtained from 17 active x - ray pulsars .
it is shown that the bolometric x - ray observations of these sources are consistent with the solid quark star pulsar model . _
pacs : _
97.60.gb , 97.60.jd , 95.30.cq pulsars ; neutron stars ; elementary particles .
And you have already written the first three sentences of the full article: it is conventionally thought that the thermal x - ray components of neutron stars are originated from the initial residual heat when the stars cool @xcite , even before the discovery of galactic x - ray sources and pulsars .
however , we will focus on this old problem in the regime of quark stars since there is no clear observational evidence to rule out quark stars or neutron stars .
we demonstrate in this paper that the observed thermal emission of isolated pulsars could be well understood in a solid quark star model ..
Please generate the next two sentences of the article | the study of quark matter phases , both hot and cold , has been an interesting topic of research in recent years . in an astrophysical context
, quark stars composed by cold quark matter have yet not been ruled out by the measured properties of pulsar - like compact stars @xcite . |
6,737 | Suppose that you have an abstract for a scientific paper: we numerically solve the boltzmann equation for trapped fermions in the normal phase using the test - particle method . after discussing a couple of tests in order to estimate the reliability of the method
, we apply it to the description of collective modes in a spherical harmonic trap .
the numerical results are compared with those obtained previously by taking moments of the boltzmann equation .
we find that the general shape of the response function is very similar in both methods , but the relaxation time obtained from the simulation is significantly longer than that predicted by the method of moments .
it is shown that the result of the method of moments can be corrected by including fourth - order moments in addition to the usual second - order ones and that this method agrees very well with our numerical simulations . .
And you have already written the first three sentences of the full article: in experiments on ultracold trapped fermi gases , there are many situations where the system is out of thermal equilibrium .
the first one is of course the trapping and cooling stage , i.e. , before the system has reached its equilibrium state which is usually the starting point for the actual experiment .
then , in some experiments the system is excited in order to observe its dynamical behavior ..
Please generate the next two sentences of the article | for instance , many experiments studied collective oscillations of the system @xcite , another example being a recent experiment at mit where the collision of two atom clouds ( both in equilibrium ) was studied @xcite . finally , often the system is not imaged directly during the experiment , but only after the trap was switched off and the system has expanded for a certain time , in order to increase its size
. the modeling of such time - dependent processes from the theoretical point of view can be quite complicated . for practical reasons , |
6,738 | Suppose that you have an abstract for a scientific paper: the configuration space of the planar three - body problem when collisions are excluded has a rich topology which supports a large set of free homotopy classes .
most classes survive modding out by rotations .
those that survive are called the reduced free homotopy classes and have a simple description when projected onto the shape sphere .
they are coded by syzygy sequences .
we prove that every reduced free homotopy class , and thus every reduced syzygy sequence , is realized by a reduced periodic solution to the newtonian planar three - body problem .
the realizing solutions have nonzero angular momentum , repeatedly come very close to triple collision , and have lots of stutters" repeated syzygies of the same type .
the heart of the proof is contained in the work by one of us on symbolic dynamics arising out of the central configurations after the triple collision is blown up using mcgehee s method . .
And you have already written the first three sentences of the full article: a basic theorem in riemannian geometry inspires our work . recall two loops in a space @xmath0 are _
freely homotopic _ if one loop can be deformed into the other without leaving @xmath0 .
the resulting equivalence classes of loops are the _ free homotopy classes_. this basic theorem asserts if @xmath0 is a compact riemannian manifold then every one of its free homotopy classes of loops is realized by a periodic geodesic ..
Please generate the next two sentences of the article | this theorem suggests an analogue for the planar newtonian three - body problem .
replace the riemannian manifold above by the configuration space @xmath0 of the planar three - body problem : the product of @xmath1 copies of the plane , minus collisions . |
6,739 | Suppose that you have an abstract for a scientific paper: mayer s second theorem in the context of a classical gas model allows us to write the coefficients of the virial expansion of pressure in terms of weighted two - connected graphs .
labelle , leroux and ducharme studied the graph weights arising from the one - dimensional hardcore gas model and noticed that the sum of these weights over all two - connected graphs with @xmath0 vertices is @xmath1 .
this paper addresses the question of achieving a purely combinatorial proof of this observation . .
And you have already written the first three sentences of the full article: this paper considers ( multivariate ) generating functions of the form : _
n=1^ _ g [ n ] ( g ) s^e(g ) , [ eq : genfn ] where @xmath2 indicates a subclass of graphs .
@xmath3 is the number of edges a graph @xmath4 ..
Please generate the next two sentences of the article | @xmath5 $ ] indicates that the graph has vertex set @xmath6 $ ] and @xmath7 is a specified positive graph weight .
the exponents of the variables @xmath8 and @xmath9 indicate the size of the vertex set , respectively , the number of edges . |
6,740 | Suppose that you have an abstract for a scientific paper: we present the first herschel pacs and spire photometric observations in a portion of the outer galaxy ( @xmath0 and @xmath1 ) as a part of the hi - gal survey .
the maps between 70 and 500 @xmath2 m , the derived column density and temperature maps , and the compact source catalog are presented .
nanten co(1 - 0 ) line observations are used to derive cloud kinematics and distances , so that we can estimate distance - dependent physical parameters of the compact sources ( cores and clumps ) having a reliable spectral energy distribution , that we separate in 255 proto - stellar and 688 starless .
both typologies are found in association with all the distance components observed in the field , up to @xmath3 kpc , testifying the presence of star formation beyond the perseus arm at these longitudes . selecting the starless gravitationally bound sources we identify 590 pre - stellar candidates .
several sources of both proto- and pre - stellar nature are found to exceed the minimum requirement for being compatible with massive star formation , based on the mass - radius relation .
for the pre - stellar sources belonging to the local arm ( @xmath4 kpc ) we study the mass function , whose high - mass end shows a power - law @xmath5 .
finally , we use a luminosity vs mass diagram to infer the evolutionary status of the sources , finding that most of the proto - stellar are in the early accretion phase ( with some cases compatible with a class i stage ) , while for pre - stellar sources , in general , accretion has not started yet . .
And you have already written the first three sentences of the full article: looking at star formation across the milky way , a large variety of different conditions is encountered , in many cases leading to observed different modalities .
one of the most relevant differences is found in the amount of star formation activity between the inner and the outer galaxy .
the smaller content of star formation in the outer galaxy is mainly related to the lower density of atomic and molecular hydrogen compared with inner galaxy @xcite ..
Please generate the next two sentences of the article | nevertheless the outer galaxy offers the chance to study the interstellar clouds and possible ongoing processes of star formation with a lower degree of confusion , also close to the galactic plane .
furthermore , reconstructing the structure of the velocity field from line observations is easier in this case , compared to the inner galaxy , thanks to the lack of distance ambiguities at any observed radial velocity . in this paper |
6,741 | Suppose that you have an abstract for a scientific paper: we apply topological methods to study the smallest non - zero number @xmath0 in the spectrum of the laplacian on finite area hyperbolic surfaces . for closed hyperbolic surfaces of genus two
we show that the set @xmath1 is unbounded and disconnects the moduli space @xmath2 . .
And you have already written the first three sentences of the full article: in this paper we identify hyperbolic surfaces with quotients of the poincar upper halfplane @xmath3 by discrete torsion free subgroups of psl@xmath4 called _ fuchsian groups_. the _ laplacian _ on @xmath5 is the differential operator @xmath6 which associates to a @xmath7- function @xmath8 the function @xmath9 for any fuchsian group @xmath10 , the induced differential operator on @xmath11 , @xmath12 is called the laplacian on @xmath13 .
it is a non - positive operator whose spectrum spec@xmath14 is contained in a smallest interval @xmath15 \subset { \mathbb r^{- } } \cup \{0\}$ ] with @xmath16 .
points in the discrete spectrum will be referred to as an _ eigenvalue_. in particular this means @xmath17 is an eigenvalue if there exists a non - zero @xmath7-function @xmath18 , called a @xmath19-_eigenfunction _ , such that @xmath20 when @xmath21 , @xmath19 is called a _ small eigenvalue _ and @xmath8 is called a _ small eigenfunction_..
Please generate the next two sentences of the article | we shall restrict ourselves to hyperbolic surfaces with finite area .
any such surface @xmath13 is homeomorphic to a closed riemann surface @xmath22 of certain genus @xmath23 from which some @xmath24 many points are removed . in that case @xmath13 |
6,742 | Suppose that you have an abstract for a scientific paper: once the set of finite graphs is equipped with an algebra structure ( arising from the definition of operations that generalize the concatenation of words ) , one can define the notion of a recognizable set of graphs in terms of finite congruences .
applications to the construction of efficient algorithms and to the theory of context - free sets of graphs follow naturally .
the class of recognizable sets depends on the signature of graph operations .
we consider three signatures related respectively to hyperedge replacement ( @xmath0 ) context - free graph grammars , to vertex replacement ( @xmath1 ) context - free graph grammars , and to modular decompositions of graphs .
we compare the corresponding classes of recognizable sets .
we show that they are robust in the sense that many variants of each signature ( where in particular operations are defined by quantifier - free formulas , a quite flexible framework ) yield the same notions of recognizability .
we prove that for graphs without large complete bipartite subgraphs , @xmath0-recognizability and @xmath1-recognizability coincide .
the same combinatorial condition equates @xmath0-context - free and @xmath1-context - free sets of graphs .
inasmuch as possible , results are formulated in the more general framework of relational structures .
the recognizability of sets of graphs .5 cm is a robust property .5 cm bruno courcelle , pascal weil .
And you have already written the first three sentences of the full article: the notion of a recognizable language is a fundamental concept in formal language theory , which has been clearly identified since the 1950 s .
it is important because of its numerous applications , in particular for the construction of compilers , and also for the development of the theory : indeed , these languages can be specified in several very different ways , by means of _ automata _ , _ congruences _ , _ regular expressions _ and _ logical formulas_. this multiplicity of quite different definitions is a clear indication that the notion is central since one arrives at it in a natural way from different approaches .
the equivalence of definitions is proved in fundamental results by kleene , myhill and nerode , elgot and bchi ..
Please generate the next two sentences of the article | the notion of a recognizable set has been extended in the 1960 s to trees ( actually to trees representing finite algebraic terms ) , to infinite words and to infinite trees . in the present article
we discuss its extension to sets of finite graphs . |
6,743 | Suppose that you have an abstract for a scientific paper: we report a serendipitous discovery of broad absorption lines that were newly formed in the spectrum of the high - redshift , luminous radio - loud quasar tex 1726@xmath0344 , in a time interval of only 12 years .
this is the first quasar showing a transition from narrow absorption lines to broad absorption lines .
it also becomes one of the few radio - loud broad absorption line quasars .
the gas cloud responsible for these broad absorption lines is derived to have parameters coinciding with those of the remnant of a tidally disrupted star . .
And you have already written the first three sentences of the full article: approximately 10% of all quasars are `` radio loud '' , in the sense that they are more luminous at radio than at optical wavelengths .
also for some unknown reason , about 10% of radio - quiet quasars show broad absorption lines ( bal ) in their spectra .
only recently have a handful of radio - loud bal quasars been discovered ( becker et al ..
Please generate the next two sentences of the article | 1997 ; brotherton et al .
1998 ) , thus changing our view that bals only appear in radio - quiet quasars . |
6,744 | Suppose that you have an abstract for a scientific paper: the investigation of events with _ initial state radiation(isr ) _ and subsequent _ radiative return _ has become an impressively successful and guiding tool in low and intermediate energy hadron physics with electron positron colliders : it allows to measure hadronic cross sections and the ratio _ r _ from threshold up to the maximum energy of the colliders running at fixed energy , to clarify reaction mechanisms and reveal substructures ( intermediate states and their decay mechanisms ) and to search for new highly excited mesonic states with @xmath0 . while being discussed since the sixties - seventies _ isr _ became a powerful tool for experimentalists only with the development of _ eva - phokhara _
@xcite , a monte carlo generator developed over almost 10 years , while increasing its complexity , which is user friendly , flexible and easy to implement into the software of existing detectors . .
And you have already written the first three sentences of the full article: the idea to use _ initial state radiation _ to measure hadronic cross sections from the threshold up to the maximum energy of colliders with fixed energies @xmath1 , to reveal reaction mechanisms and to search for new mesonic states consists in exploiting the process @xmath2 to reduce the centre of mass energies of the colliding electrons and positrons and consequently the energy squared @xmath3 of the final state by emitting 1 or more photons .
the method is particularly well suited for the modern meson factories like @xmath4 running at the @xmath5-resonance , _ pep - ii _ , _ kekb _ at the @xmath6-resonance with their high luminosities which compensate for the @xmath7 suppression of the emission of a photon .
@xmath4 , _ pep - ii _ and _ kekb _ cover the energy regions up to 1.02 gev and up to 10.6 gev , respectively ( restricted for the latter actually up to 4 ... 5 gev if hard photons are detected ) ..
Please generate the next two sentences of the article | a big advantage of the _ isr _ method are the low point - to - point systematic errors of the hadronic energy spectra because the luminosity , the energy of the electrons and positrons and many of the various contributions to the detection efficiencies are determined once for the whole spectrum . as a consequence
the overall normalization error is the same for all energies of the hadronic system . |
6,745 | Suppose that you have an abstract for a scientific paper: in models of galaxy formation in a hierarchical universe , elliptical galaxies form through the merging of smaller disk systems .
these models yield a number of testable predictions if reliable techniques for determining the relative ages and compositions of the stellar populations of different galaxies can be found : 1 ) ellipticals in low - density environments form later than ellipticals in clusters , 2 ) more massive ellipticals form later , 3 ) more massive ellipticals form in dissipationless mergers from disk galaxies with low gas content . while colours and the balmer line strengths of galaxies can be used to infer the average ages of the stellar populations of ellipticals , @xmath0/fe element ratios carry information about the timescale over which star formation took place . here
we present preliminary results from semi - analytic models for the distribution of mg / fe ratios in galaxies as a function of morphological type , luminosity and environment . .
And you have already written the first three sentences of the full article: according to the standard theoretical paradigm , the structures observed in the universe today were formed by the gravitational amplification of small perturbations in an initially gaussian dark matter density field .
small scale overdensities were the first to collapse , and the resulting objects subsequently merged under the influence of gravity to form larger structures such as groups and clusters of galaxies .
galaxies formed within dense _ halos _ of dark matter , where gas was able to reach high enough overdensities to cool , condense and form stars . the quiescent cooling of gas within a dark matter halo results in the formation of a rotationally - supported disk system at the centre of the halo ..
Please generate the next two sentences of the article | when halos merge with each other , a bound group of galaxies is produced .
dynamical friction will cause the orbits of the group members to erode over time , and the galaxies to spiral in towards the centre of the halo and merge . |
6,746 | Suppose that you have an abstract for a scientific paper: we have found the @xmath0 color versus @xmath1 color gradient space can be used for highly successful morphology classification of galaxies in the sloan digital sky survey . in this
space galaxies form early and late type branches well - separated from each other .
the location of galaxies along the branches reflects the degree and locality of star formation activity , and monotonically corresponds to the sequence of morphological subclasses .
when the concentration index is used together , the completeness and reliability of classification reaches about 91% for a training set of sdss galaxies brighter than @xmath2 . at faintest magnitudes ( @xmath3 ) of the sdss spectroscopic sample ,
the performance still remains at about 88% .
the new classification scheme will help us find accurate relations of galaxy morphology with spatial and temporal environments , and help one understand the origin of morphology of galaxies . .
And you have already written the first three sentences of the full article: unlike stars , galaxies show diverse shapes .
the belief that the difference in appearance reflects the generic character has motivated morphological classification of galaxies . since the 1920s the simple scheme suggested by hubble ( hubble 1926 ) based on single band images of bright galaxies has been widely adopted .
the essence of hubble s scheme and its elaborations ( de vaucouleurs 1991 ; kormendy 1979 ; de vaucouleurs 1959 ; sandage 1961 ) is to divide galaxies into early and late types ..
Please generate the next two sentences of the article | the early types are further divided into ellipticals and lenticulars , and the late types into spirals ( unbarred and barred ) and irregulars .
any one who looks directly into galaxy images immediately realize that shapes of galaxies are much more diverse than this , but also that the simple hubble sequence catches the major features of galaxy morphology . as unprecedentedly large sets of digital images of galaxies such as the sloan digital sky survey ( sdss , full details of the sdss are available at http://www.sdss.org . |
6,747 | Suppose that you have an abstract for a scientific paper: we present analytic results for ground - state properties of hubbard - type models in terms of the gutzwiller variational wave function with non - zero values of the magnetization @xmath0 . in dimension @xmath1
@xmath2 @xmath3 approximation - free evaluations are made possible by appropriate canonical transformations and an analysis of umklapp processes .
we calculate the double occupation and the momentum distribution , as well as its discontinuity at the fermi surface , for arbitrary values of the interaction parameter @xmath4 , density @xmath5 , and magnetization @xmath0 .
these quantities determine the expectation value of the one - dimensional hubbard hamiltonian for any symmetric , monotonically increasing dispersion @xmath6 .
in particular for nearest - neighbor hopping and densities away from half filling the gutzwiller wave function is found to predict ferromagnetic behavior for sufficiently large interaction @xmath7 . .
And you have already written the first three sentences of the full article: quantum - mechanical many - body problems can almost never be solved exactly . in this situation
variational wave functions have proved to be particularly useful .
although they describe correlations among the particles only in an approximate way , they have the advantage of being explicit and physically intuitive ..
Please generate the next two sentences of the article | in particular , they allow for investigations even when standard perturbation theory is not applicable , or is untractable .
variational wave functions can , for example , be obtained by applying a suitably chosen correlation operator ( e. g. , the interaction part of the hamiltonian under investigation ) to a simple one - particle wave function . |
6,748 | Suppose that you have an abstract for a scientific paper: we investigate the landshoff - nachtmann two - gluon - exchange model of the pomeron using gluon propagators computed in the landau gauge within quenched lattice qcd calculations .
we first determine an effective gluon - quark coupling by constraining the pomeron - quark coupling to its phenomenological value @xmath0 .
we then provide predictions for a variety of diffractive processes . as the propagators have been evaluated entirely from qcd first principles (
although in the quenched approximation ) , our results provide a consistency check of the landshoff - nachtmann model .
we address the issue of the possible gauge - dependence of our results , which will be the object of a future study .
edinburgh preprint : 95/559 + liverpool preprint : lth-363 + hep - lat/9511031 the landshoff - nachtmann pomeron on the lattice + _ ukqcd collaboration _ + * d.s .
henty , c. parrinello and d.g .
richards * + department of physics and astronomy , university of edinburgh , edinburgh eh9 3jz , scotland + .
And you have already written the first three sentences of the full article: the description of diffractive hadronic physics in terms of the exchange of a `` pomeron '' has proved remarkably durable , and has successfully withstood the advent of qcd .
interest in the pomeron has been renewed by recent results from hera .
total cross sections and diffractive processes are essentially soft in nature , and thus do not fall within the realm of perturbative qcd ..
Please generate the next two sentences of the article | thus any fixed - order perturbative calculation must be regarded purely as a model of the interaction , but one which may be representative of an all - orders qcd result
. nevertheless , a successful phenomenological model of pomeron exchange is provided by two - gluon - exchange ( 2ge ) @xcite . |
6,749 | Suppose that you have an abstract for a scientific paper: a recently proposed variational approach for general relativity where , in addition to the metric tensor , two independent affine connections enter the action as dynamical variables , is revised .
field equations always reduce to the einstein field equations for any dependence of the matter action upon an independent connection . .
And you have already written the first three sentences of the full article: lagrangian formulations of general relativity abound in literature , but rather than differing in the choice of the lagrangian density they differentiate one another by the variable upon which the variation of the action has to be taken
. the most famous examples are pheraps the metric and palatini variational approaches .
the first one , sometimes called second order variation , considers the metric tensor as the only dynamical field variable while the second one , also known as first order variation , assumes the connection to be an independent field ..
Please generate the next two sentences of the article | though both approaches reproduce the einstein field equations in vacuum , the latter gives rise to another theory whenever the independent connection is allowed to appear inside the matter action . in this case
the theoretical framework goes under the name of metric - affine variational principle and it is known not to recover general relativity in the presence of spinor fields , for example . the scope of the present paper is to summarize the basic features of a new variational approach recently proposed@xcite . together with the metric , two completely independent connections , with no _ a priori _ assumpions , are considered as dynamical variables entering the gravitational action for general relativity . |
6,750 | Suppose that you have an abstract for a scientific paper: + the complex multiwavelength emission of grb afterglow 130427a ( monitored in the radio up to 10 days , in the optical and x - ray until 50 days , and at gev energies until 1 day ) can be accounted for by a hybrid reverse - forward shock synchrotron model , with inverse - compton emerging only above a few gev .
the high ratio of the early optical to late radio flux requires that the ambient medium is a wind and that the forward - shock synchrotron spectrum peaks in the optical at about 10 ks .
the latter has two consequences : the wind must be very tenuous and the optical emission before 10 ks must arise from the reverse - shock , as suggested also by the bright optical flash that raptor has monitored during the prompt emission phase ( @xmath0 100 s ) .
the vla radio emission is from the reverse - shock , the swift x - ray emission is mostly from the forward - shock , but the both shocks give comparable contributions to the fermi gev emission .
the weak wind implies a large blast - wave radius ( @xmath1 pc ) , which requires a very tenuous circumstellar medium , suggesting that the massive stellar progenitor of grb 130427a resided in a super - bubble .
radiation mechanisms : non - thermal relativistic processes shock waves .
And you have already written the first three sentences of the full article: gamma - ray burst ( grb ) 130427a may well be the burst with the most comprehensive afterglow follow - up , its multiwavelength monitoring covering radio , optical , x - ray , and @xmath2-ray frequencies , and extending from seconds to tens of days after trigger .
the x - ray _ prompt _ emission ( up to 100 s ) was accompanied by the second brightest optical flash , monitored by raptor ( vestrand et al 2013 ) , with the optical afterglow light - curve displaying a steepening at 300 s and a flattening at 10 ks . the swift x - ray light - curve ( x - ray light - curve repository
evans et al 2009 ) is consistent with a single power - law from 500 s to 5 ms ..
Please generate the next two sentences of the article | the fermi - lat @xmath2-ray light - curve ( tam et al 2013 ) displays a peak at 1020 s , simultaneous with the optical flash peak , and a steepening at 550800 s ( zhu et al 2013 ) . the vla radio light - curves ( laskar et al 2013 ) display a slow decay at 1 - 10 day . with such a rich dataset ,
grb afterglow 130427a demands a theoretical interpretation , done here in the framework of the external - shock model ( & rees 1997 ) where some relativistic ejecta , produced by the black - hole resulting from the core - collapse of a massive star , drive a _ forward - shock _ into the ambient medium while the ejecta are energized by the _ reverse - shock_. the synchrotron and inverse - compton emissions from both shocks are calculated assuming that electrons and magnetic field acquire a certain fraction of the post - shock energy . |
6,751 | Suppose that you have an abstract for a scientific paper: the belle - ii experiment is expected to collect large data samples at the @xmath0 and @xmath1 resonances to study primarily @xmath2 and @xmath3 mesons .
we discuss what other data above the @xmath4 threshold are of interest .
we propose to perform a high - statistics energy scan from the @xmath4 threshold up to the highest possible energy , and to collect data at the @xmath5 and at higher mass states if they are found in the scan .
we emphasize the interest in increasing the maximal energy from @xmath6 to @xmath7 in the future .
these data are needed for investigation of bottomonium and bottomonium - like states .
ftpi - minn-16/28 + umn - th-3606/16 * bottomonium - like states : physics case for energy scan above the @xmath4 threshold at belle - ii * a. e. bondar@xmath8 , r. v. mizuk@xmath9 and m. b. voloshin@xmath10 + + + + + + + .
And you have already written the first three sentences of the full article: conventional bottomonium is an approximately non - relativistic system . out of 34 expected @xmath11 energy levels below the @xmath4 threshold @xcite 15
have been observed @xcite .
the masses and decays of these states are well described by potential models @xcite ..
Please generate the next two sentences of the article | there are five states with @xmath12 pairs above the @xmath4 threshold : three isospin - zero vector states @xmath13 , @xmath14 and @xmath15 [ or @xmath0 , @xmath1 and @xmath5 according to the potential model assignment ] , and two isospin - one axial states @xmath16 and @xmath17 . the isospin - one states are obviously exotic with minimal quark content @xmath18 .
but the isospin - zero states also have properties unexpected for a pure @xmath12 pair . |
6,752 | Suppose that you have an abstract for a scientific paper: we report the discovery of a cluster of galaxies via its weak gravitational lensing effect on background galaxies , the first spectroscopically confirmed cluster to be discovered through its gravitational effects rather than by its electromagnetic radiation .
this fundamentally different selection mechanism promises to yield mass - selected , rather than baryon or photon - selected , samples of these important cosmological probes .
we have confirmed this cluster with spectroscopic redshifts of fifteen members at z=0.276 , with a velocity dispersion of 615 km s@xmath0 .
we use the tangential shear as a function of source photometric redshift to estimate the lens redshift independently and find @xmath1 . the good agreement with the spectroscopy
indicates that the redshift evolution of the mass function may be measurable from the imaging data alone in shear - selected surveys . .
And you have already written the first three sentences of the full article: clusters of galaxies are essential tools for developing our understanding of structure formation and for probing cosmological parameters . in particular
, the redshift evolution of the cluster mass function is a sensitive diagnostic of @xmath2 , sufficiently sensitive that the existence of even one or two massive clusters at @xmath3 favors a low - density universe ( donahue _ et al .
_ 1998 , ebeling _.
Please generate the next two sentences of the article | et al . _ 2000 ) .
this argument assumes gaussianity in the primordial fluctuations ; clusters are equally useful at constraining primordial non - gaussianity given an independent measure of @xmath2 ( robinson , gawiser & silk 1999 ) . |
6,753 | Suppose that you have an abstract for a scientific paper: we extend next - to - leading logarithmic threshold and joint resummation for prompt photon production to include leading collinear effects .
the impact of these effects is assessed for both fixed - target and collider kinematics .
we find them in general to be small , but noticeable .
nikhef/2007 - 008 + itp - uu-07/23 + imsc-2007/04/5 * soft - collinear effects in prompt photon production * + rahul basu@xmath0 , eric laenen@xmath1 , anuradha misra@xmath2 , patrick motylinski@xmath3 + @xmath0 _ the institute of mathematical sciences , cit campus , taramani , chennai 600 113 , india _
+ @xmath3_nikhef theory group , kruislaan 409 , 1098 sj amsterdam , the netherlands _ + @xmath4_institute for theoretical physics , utrecht university + leuvenlaan 4 , 3584 ce utrecht , the netherlands
_ + @xmath2 _ department of physics , university of mumbai , santacruz(e ) , mumbai , 400098 , india _ + .
And you have already written the first three sentences of the full article: the perturbative qcd description of many observables measured at colliders is plagued by large corrections arising from soft and collinear parton emission , even for fairly generic kinematical conditions .
for example , near threshold , large logarithmic corrections remain @xcite after cancellation of singular virtual and real gluon contributions , their large size being a result of the nearby threshold restricting the real gluons to be soft . in terms of a ( mellin )
variable @xmath5 , in terms of which threshold is approached by @xmath6 , such large threshold corrections take the form ( @xmath7 ) , @xmath8 where the @xmath9 depend in general on the process ..
Please generate the next two sentences of the article | another example @xcite is when an identified part @xmath10 of a final state has acquired small transverse momentum by soft recoil ( @xmath11 ) against the remaining , unmeasured part of the final state .
then the perturbative expression for the differential cross section with respect to @xmath12 of @xmath10 takes again the form of eq . , but with different coefficients @xmath9 and with @xmath13 , @xmath14 being the impact parameter fourier conjugate to @xmath11 . |
6,754 | Suppose that you have an abstract for a scientific paper: for nearly half a century the supersolid phase of matter has remained mysterious , not only eluding experimental observation , but also generating a great deal of controversy among theorists .
recent discovery of what is interpreted as a non - classical moment of inertia at low temperature in solid @xmath0he @xcite has elicited much excitement as a possible first observation of a supersolid phase . in the two years following the discovery ,
however , more puzzles than answers have been provided to the fundamental issue of whether the supersolid phase exists , in helium or any other naturally occurring condensed matter system . presently , there is no established theoretical framework to understand the body of experimental data on 4 .
different microscopic mechanisms that have been suggested to underlie superfluidity in a perfect quantum crystal do not seem viable for 4 , for which a wealth of experimental and theoretical evidence points to an insulating crystalline ground state .
this perspective addresses some of the outstanding problems with the interpretation of recent experimental observations of the apparent superfluid response in 4 ( seen now by several groups @xcite ) and discusses various scenarios alternative to the homogeneous supersolid phase , such as superfluidity induced by extended defects of the crystalline structure which include grain boundaries , dislocations , anisotropic stresses , etc .
can a metastable superfluid glassy " phase exist , and can it be relevant to some of the experimental observations ?
one of the most interesting and unsolved fundamental questions is what interatomic potentials , given the freedom to design one , can support an ideal supersolid phase in continuous space , and can they be found in nature . .
And you have already written the first three sentences of the full article: the textbook notion of a perfect crystal at @xmath1 , is that of a periodic array of unit cells , all comprising the same _ integer _ number of particles , @xmath2 , where @xmath3 is the unit cell volume and @xmath4 is the average particle density profile . for simplicity ,
let us consider a single component crystal similar to @xmath0he .
we assume that the elementary constituents ( atoms or molecules ) can be regarded as structureless particles ; furthermore , we assume that they obey bose statistics ..
Please generate the next two sentences of the article | the supersolid phase ( sfs ) can be generally defined as one that combines crystalline properties , such as shear modulus and broken translation symmetry , with frictionless mass transport through the solid bulk .
the striking , simultaneous presence of solid and superfluid properties in the same condensed matter system , will result in a number of phenomena that defy our everyday experience . |
6,755 | Suppose that you have an abstract for a scientific paper: we give a direct non - abstract proof of the spectral mapping theorem for the helffer - sjstrand functional calculus for linear operators on banach spaces with real spectra and consequently give a new non - abstract direct proof for the spectral mapping theorem for self - adjoint operators on hilbert spaces .
our exposition is closer in spirit to the proof by explicit construction of the existence of the functional calculus given by davies .
we apply an extension theorem of seeley to derive a functional calculus for semi - bounded operators .
+ + * ams subject classification : 47a60 + keywords : functional calculus , spectral mapping theorem , spectrum , * .
And you have already written the first three sentences of the full article: the helffer - sjstrand formula was established in @xcite in the following proposition [ hsformula ] let @xmath0 be a self - adjoint operator ( not necessarily bounded ) on a hilbert space @xmath1 .
suppose @xmath2 is in @xmath3 and @xmath4 in @xmath5 is an extension of @xmath2 such that @xmath6 on @xmath7 .
then we have @xmath8 where @xmath9 is the lebesgue measure on @xmath10 ..
Please generate the next two sentences of the article | the existence of the functional calculus was assumed by the authors .
davies@xcite showed that the formula ( equation [ hsformula ] ) yielded a new approach to the functional calculus for linear operators on banach spaces under the following hypothesis [ e : hypothesis ] @xmath0 is a closed densely defined operator on a banach space @xmath11 with spectrum @xmath12 . |
6,756 | Suppose that you have an abstract for a scientific paper: the paper presents an evolutionary game - theoretic approach to open access publishing as an asymmetric game between scientists and publishers .
we show how the ordinary differential equations of the model presented can be written as a system of hamiltonian partial differential equations .
the understanding of the setting as a hamiltonian system implies some properties reflecting the qualitative behavior of the system . .
And you have already written the first three sentences of the full article: the topic of open access publishing has been extensively and controversially discussed . for general information
see , for instance , @xcite .
there are many models of open access named after different colors such as golden or green roads to open access @xcite , but we do not want to go into more details , here . concerning scientific publishing particularly in mathematics , we refer to @xcite and @xcite as well as to the references therein ..
Please generate the next two sentences of the article | in @xcite the authors illustrate a game - theoretic approach to open access publishing in order to understand different publication patterns within different scientific disciplines .
the underlying observation is that there are communities where open access publishing is widely adopted , whereas other scientific communities are far away from practicing any open access publishing . |
6,757 | Suppose that you have an abstract for a scientific paper: big - bang cosmology and ideas for possible physics beyond the standard model of particle physics are introduced .
the density budget of the universe is audited , and the issues involved in calculating the baron density from microphysics are mentioned , as is the role of cold dark matter in the formation of cosmological structures .
candidates for cold dark matter are introduced , with particular attention to the lightest supersymmetric particle and metastable superheavy relics .
prospects for detecting supersymmetric dark matter in non - accelerator experiments are assessed , and the possible role of decays in generating ultra - high - energy cosmic rays is discussed .
more details of these and other astroparticle topics are presented during the rest of this summer institute .
12m_1/2 12m_1/2 _ _
r /#1#1 _ # 1#2 _ opening lecture at the 31st slac summer institute , july 2003 : psn l01
_ + cern - th/2003 - 268 @xmath0 astro - ph/0310911 .
And you have already written the first three sentences of the full article: my task in this opening lecture is to set the stage for the subsequent lectures that develop in more detail the connections between particle physics and cosmology .
to do so , i first recall the essential aspects of standard big - bang cosmology , emphasizing that the questions it raises about the early history of the universe can only be answered by particle physics .
the latter is described by its own standard model , which makes successful quantitative predictions for accelerator experiments , but leaves open many fundamental questions ..
Please generate the next two sentences of the article | these include the origin of particle masses , the proliferation of different types of elementary particles and the possible unification of all the particle interactions . in combination with accelerator experiments
, astrophysics and cosmology may cast important light on the solutions of these problems . according to astrophysicists and cosmologists , |
6,758 | Suppose that you have an abstract for a scientific paper: the ubiquity of m dwarfs , combined with the relative ease of detecting terrestrial - mass planets around them , has made them prime targets for finding and characterising planets in the `` habitable zone '' ( hz ) .
however , _ kepler _ finds that terrestrial - mass exoplanets are often born with voluminous h / he envelopes , comprising mass - fractions ( @xmath0 ) @xmath1% . if these planets retain such envelopes over gyr timescales , they will not be `` habitable '' even within the hz . given the strong x - ray / uv fluxes of m dwarfs , we study whether sufficient envelope mass can be photoevaporated away for these planets to become habitable .
we improve upon previous work by using hydrodynamic models that account for radiative cooling as well as the transition from hydrodynamic to ballistic escape . adopting a template active m dwarf xuv spectrum , including stellar evolution , and considering both evaporation and thermal evolution ,
we show that : _ ( 1 ) _ the mass - loss is ( considerably ) lower than previous estimates that use an `` energy - limited '' formalism and ignore the transition to jeans escape ; _ ( 2 ) _ at the inner edge of the hz , planets with core mass @xmath2 can lose enough h / he to become habitable if their initial envelope mass - fraction is @xmath31% ; _ ( 3 ) _ at the outer edge of the hz , evaporation can not remove a @xmath31% h / he envelope even from cores down to 0.8 .
thus , if planets form with bulky h / he envelopes , only those with low - mass cores may eventually be habitable .
cores @xmath4 1 , with @xmath41% natal h / he envelopes , will _ not _ be habitable in the hz of m dwarfs .
ps .
p_surf 1t_bb , ms .
And you have already written the first three sentences of the full article: m dwarfs comprise the bulk ( @xmath375% ) of the stellar population of our galaxy .
moreover , their low masses and small radii , compared to sun - like stars , make planets of a given mass , size and orbital separation much easier to detect around them via both the transit and doppler methods . in addition , the habitable zone ( hz ) of such low luminosity red dwarfs lies considerably closer to the central star than in the case of solar - types ; this further enhances the transit and doppler signatures of hz planets , and also allows a larger number of planetary orbits to be observed in a given time , making the detection and characterisation of such planets even easier .
consequently , the next generation of missions investigating exoplanets are aimed at later - type stars rather than the mainly solar - type ones targeted by _ kepler _ , and discussions of exoplanet habitability increasingly focus on m dwarf systems ..
Please generate the next two sentences of the article | there are many complications pertaining to the habitability of planets around m - dwarfs , even if they possess surface temperature and pressure conditions favourable to liquid water , such as tidal locking ( e.g. * ? ? ?
* ; * ? ? ? |
6,759 | Suppose that you have an abstract for a scientific paper: chimera states consisting of domains of coherently and incoherently oscillating nonlocally - coupled phase oscillators in systems with spatial inhomogeneity are studied .
the inhomogeneity is introduced through the dependence of the oscillator frequency on its location .
two types of spatial inhomogeneity , localized and spatially periodic , are considered and their effects on the existence and properties of multi - cluster and traveling chimera states are explored .
the inhomogeneity is found to break up splay states , to pin the chimera states to specific locations and to trap traveling chimeras .
many of these states can be studied by constructing an evolution equation for a complex order parameter .
solutions of this equation are in good agreement with the results of numerical simulations .
pacs numbers : : may be entered using the ` \pacs{#1 } ` command . .
And you have already written the first three sentences of the full article: networks of coupled oscillators have been extensively studied for many years , owing to their wide applicability in physics , chemistry , and biology . as examples we mention laser arrays , josephson junctions , populations of fireflies , etc . @xcite .
the phase - only models have proved to provide useful models for systems with weak coupling .
the best known model of this type is the kuramoto model in which the oscillators are described by phase variables @xmath0 and coupled to others through a sinusoidal function @xcite ..
Please generate the next two sentences of the article | these models exhibit a transition to collective synchronization as the coupling strength increases , a process that has been described as a phase transition .
a general form of these systems is as follows : @xmath1 here @xmath2 is the natural frequency of oscillator @xmath3 , @xmath4 represents the coupling between oscillators @xmath3 and @xmath5 , @xmath6 is a phase lag and @xmath7 is the overall coupling strength . |
6,760 | Suppose that you have an abstract for a scientific paper: transport through a metallic carbon nanotube is considered , where electrons are injected in the bulk by a scanning tunneling microscope tip .
the charge current and noise are computed both in the absence and in the presence of one dimensional fermi liquid leads . for an infinite homogeneous nanotube ,
the shot noise exhibits effective charges different from the electron charge .
noise correlations between both ends of the nanotube are positive , and occur to second order only in the tunneling amplitude .
the positive correlations are symptomatic of an entanglement phenomenon between quasiparticles moving right and left from the tip .
this entanglement involves many body states of the boson operators which describe the collective excitations of the luttinger liquid . .
And you have already written the first three sentences of the full article: over the years , the study of current noise and noise correlations has become a respected and useful diagnosis for transport measurements on mesoscopic conductors .
theoretically , noise was first computed mostly for non interacting systems @xcite .
however , it soon became clear that low frequency noise could be used to isolate the quasiparticle charge @xcite and to study the statistical correlations @xcite in specific quasi one dimensional correlated electron systems , such as the edge waves in the quantum hall effect . in these chiral luttinger liquids ,.
Please generate the next two sentences of the article | the charge of the collective excitations along the edges corresponds to the electron charge multiplied by the filling factor .
attention is now turning towards conductors individual nano - objects which occur naturally , and which can be connected to current / voltage probes in order to perform a transport experiment . |
6,761 | Suppose that you have an abstract for a scientific paper: in the past two decades , many research groups worldwide have tried to understand and categorize simple regimes in the charge transfer of such biological systems as dna .
theoretically speaking , the lack of exact theories for electron nuclear dynamics on one side , and poor quality of the parameters needed by model hamiltonians and nonadiabatic dynamics alike ( such as couplings and site energies ) on the other , are the two main difficulties for an appropriate description of the charge transfer phenomena . in this work , we present an application of a previously benchmarked and linear - scaling subsystem dft method for the calculation of couplings , site energies and superexchange decay factors ( @xmath0 ) of several biological donor
acceptor dyads , as well as double stranded dna oligomers comprised of up to 5 base pairs .
the calculations are all - electron , and provide a clear view of the role of the environment on superexchange couplings in dna they follow experimental trends and confirm previous semiempirical calculations .
the subsystem dft method is proven to be an excellent tool for long - range , bridge - mediated coupling and site energy calculations of embedded molecular systems . .
And you have already written the first three sentences of the full article: for the past two decades , charge transfer ( ct ) phenomena in biosystems have been intensively studied due to their role in biological functions as well as in potential applications related to nanosensors and molecular optoelectronics .
oxidative damage in cells @xcite as well as the possibility of using dna as a biomolecular nanowire @xcite have inspired studies related to the hole migration through the dna nucleobases on a sequence of radical cation states . a major target for oxidants is guanine ( g ) , the nucleobase with the lowest ionization potential of the four dna bases .
oxidation of guanine leads to a radical cation @xmath1 , the hole may transfer to a neutral @xmath2 , restoring neutrality in the former and creating a radical cation in the latter ..
Please generate the next two sentences of the article | especially the ct in dna oligomers has been extensively studied both experimentally and theoretically with many techniques .
experiments have initially yielded different results , such as dna being a conductor @xcite , semiconductor @xcite , and insulator @xcite . |
6,762 | Suppose that you have an abstract for a scientific paper: gaia has been approved to provide the data needed to quantify the formation and evolution of the milky way galaxy , and its near neighbours .
that requires study of all four key galactic stellar populations : bulge , halo , thick disk , thin disk .
the complex analysis methodologies required to model gaia kinematic data are being developed , and in the interim applied to the relatively simple cases of the satellite dsph galaxies .
these methodologies , illustrated here , show that we will be able to interpret the gaia data .
they also quantify what data gaia must provide .
it is very unlikely in the present design that gaia will be able to provide either radial velocities or worthwhile photometry for study of two of the key science goals : the galactic bulge and the ( inner ) galactic old disk .
the implication is that the radial velocity spectrometer and the medium band photometer should be optimised for study of low density fields
suitable for their low spatial resolution and the broad band photometry must be optimised for inner galaxy astrophysical studies .
# 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: [ fig1 ] the gaia mission has been approved to provide for the first time a clear picture of the formation , structure , evolution , and future of the entire milky way .
in addition , as secondary goals , gaia will contribute to many other branches of astrophysics , especially stellar and solar system minor body astrophysics , with a valuable contribution to cosmology and fundamental physics .
this clear scientific prioritisation must drive the design , and all compromises ..
Please generate the next two sentences of the article | understanding the structure and evolution of the galaxy requires three complementary observational approaches : * carrying out a full census of all the objects in a large , representative , part of the galaxy ; * mapping quantitatively the spatial structure of the galaxy ; * measuring the motions of objects in three - dimensions to determine the gravitational field and the stellar orbits . in other words ,
what is required are complementary measurements of distances ( astrometry ) , photometry to determine both extinction and intrinsic stellar properties , and the radial velocities along our line of sight . |
6,763 | Suppose that you have an abstract for a scientific paper: the covariance evolution is a system of differential equations with respect to the covariance of the number of edges connecting to the nodes of each residual degree . solving the covariance evolution
, we can derive distributions of the number of check nodes of residual degree 1 , which helps us to estimate the block error probability for finite - length ldpc code .
amraoui et al
. resorted to numerical computations to solve the covariance evolution . in this paper
, we give the analytical solution of the covariance evolution . .
And you have already written the first three sentences of the full article: gallager invented low - density parity - check ( ldpc ) codes @xcite in 1963 .
ldpc codes are linear codes defined by sparse bipartite graphs .
luby et al . introduced the _ peeling algorithm _ (.
Please generate the next two sentences of the article | pa ) @xcite for the binary erasure channel ( bec ) .
pa is an iterative algorithm which is defined on tanner graphs . |
6,764 | Suppose that you have an abstract for a scientific paper: we have used the high sensitivity and resolution of the iram interferometer to produce sub - arcsecond @xmath0co j=2 - 1 images of 9 protoplanetary disks surrounding ttauri stars in the taurus - auriga cloud ( 7 singles and 2 binaries ) .
the images demonstrate the disks are in keplerian rotation around their central stars . using the least square fit method described in guilloteau & dutrey ( 1998 )
, we derive the disk properties , in particular its inclination angle and rotation velocity , hence the dynamical mass .
since the disk mass is usually small , this is a _
direct _ measurement of the stellar mass .
typically , we reach an internal precision of 10% in the determinations of stellar mass . the over - all accuracy is limited by the uncertainty in the distance to a specific star . in a distance independent way , we compare the derived masses with theoretical tracks of pre - main - sequence evolution . combined with the mean distance to the taurus region ( 140 pc ) , for stars with mass close to 1 , our results tend to favor the tracks with cooler photospheres ( higher masses for a given spectral type ) .
we find that in uz tau e the disk and the spectroscopic binary orbit appear to have different inclinations . .
And you have already written the first three sentences of the full article: nearly all of our knowledge about the masses and ages of low mass young stars comes from their location in the hr diagram relative to theoretical calculations of stellar evolution to the main sequence . despite considerable advances over the past 5 - 10 years in understanding the structure and atmospheres of stars of mass m@xmath1 ,
comparison of the currently available predicted evolutionary paths of young stars shows obvious differences .
empirical tests of the calculations have not been possible until recently because astronomers have not had independent measurements of either the mass or age of a young star ..
Please generate the next two sentences of the article | this situation is changing rapidly .
one way to test the calculated tracks is to investigate whether they yield the same ages for stars expected to be coeval on physical grounds . |
6,765 | Suppose that you have an abstract for a scientific paper: we have modelled the zeno effect control - sign gate of franson et al ( pra 70 , 062302 , 2004 ) and shown that high two - photon to one - photon absorption ratios , @xmath0 , are needed for high fidelity free standing operation .
hence we instead employ this gate for cluster state fusion , where the requirement for @xmath0 is less restrictive . with the help of partially offline one - photon and two - photon distillations , we can achieve a fusion gate with unity fidelity but non - unit probability of success .
we conclude that for @xmath1 , the zeno fusion gate will out perform the equivalent linear optics gate . .
And you have already written the first three sentences of the full article: quantum bits ( qubits ) based on polarization or spatial degrees of freedom of optical modes have several advantages : they are easily manipulated and measured ; they exist in a low noise environment and ; they are easily communicated over comparitively long distances .
recently considerable progress has been made on implementing two qubit gates in optics using the measurement induced non - linearities proposed by knill , laflamme and milburn @xcite .
non - deterministic experimental demonstrations have been made @xcite and theory has found significant ways to reduce the resource overheads @xcite . nevertheless , the number of photons and gate operations required to implement a near deterministic two qubit gate remains high ..
Please generate the next two sentences of the article | a possible solution to this problem is the optical quantum zeno gate suggested by franson et al @xcite , @xcite .
this gate uses passive two - photon absorption to suppress gate failure events associated with photon bunching at the linear optical elements , using the quantum zeno effect @xcite . in principle a near deterministic , high fidelity control - sign ( cz ) gate can be implemented between a pair of photonic qubits in this way |
6,766 | Suppose that you have an abstract for a scientific paper: string propagation is investigated in de sitter and black hole backgrounds using both exact and approximative methods .
the circular string evolution in de sitter space is discussed in detail with respect to energy and pressure , mathematical solution and physical interpretation , multi - string solutions etc .
we compare with the circular string evolution in the @xmath0 dimensional black hole anti de sitter spacetime and in the equatorial plane of ordinary @xmath1 dimensional stationary axially symmetric spacetime solutions of einstein general relativity . using an approximative string perturbation approach we consider also generic string evolution and propagation in all these curved spacetimes . + arne l. larsen + .
And you have already written the first three sentences of the full article: the classical and quantum propagation of strings in curved spacetimes has attracted a great deal of interest in recent years .
the main complication , as compared to the case of flat minkowski space , is related to the non - linearity of the equations of motion .
it makes it possible to obtain the complete analytic solution only in a very few special cases like conical spacetime @xcite and plane wave / shock wave backgrounds @xcite ..
Please generate the next two sentences of the article | there are however also very general results concerning integrability and solvability for maximally symmetric spacetimes @xcite and gauged wzw models @xcite .
these are the exceptional cases , generally the string equations of motion in curved spacetimes are not integrable and even if they are , it is usually an extremely difficult task to actually separate the equations , integrate them and finally write down the complete solution in closed form . |
6,767 | Suppose that you have an abstract for a scientific paper: eklund et al . ( 2002 ) present a graphical technique aimed at simplifying the verification of various category - theoretic constructions , notably the composition of monads . in this note
we take a different approach involving string rewriting .
we show that a given tuple @xmath0 is a monad if and only if @xmath1 is a terminal object in a certain category of strings and rewrite rules , and that this fact can be established by proving confluence of the rewrite system .
we illustrate the technique on the monad composition problem . we also give a characterization of adjunctions in terms of rewrite categories . _ in honor of ji admek on the occasion of his seventieth birthday _ .
And you have already written the first three sentences of the full article: as common constructions in the theory of data types and programming language semantics become better understood , there is a natural tendency toward generality .
one desires to isolate common underlying principles , to unify related notions in a common framework , and to provide powerful abstract tools for reasoning and understanding .
a good example of one successful such enterprise is the use of monads in functional and logic programming @xcite ..
Please generate the next two sentences of the article | monads provide a clean way to combine modules or extend functionality of programming languages or data structures with new features such as continuations , state , and concurrency @xcite .
they have been applied to parsing and type checking @xcite , semantics of nondeterministic and probabilistic computation @xcite , and unification in logic programming @xcite . |
6,768 | Suppose that you have an abstract for a scientific paper: using a sample of spiral galaxies selected from the sloan digital sky survey data release 7 ( sdss dr7 ) and galaxy zoo 2 ( gz2 ) , we investigate the alignment of spin axes of spiral galaxies with their surrounding large scale structure , which is characterized by the large - scale tidal field reconstructed from the data using galaxy groups above a certain mass threshold .
we find that the spin axes only have weak tendency to be aligned with ( or perpendicular to ) the intermediate ( or minor ) axis of the local tidal tensor .
the signal is the strongest in a environment where all the three eigenvalues of the local tidal tensor are positive .
compared to the alignments between halo spins and local tidal field obtained in n - body simulations , the above observational results are in best agreement with those for the spins of inner regions of halos , suggesting that the disk material traces the angular momentum of dark matter halos in the inner regions . .
And you have already written the first three sentences of the full article: the galaxy distribution in large spectroscopic surveys , such as sloan digital sky survey ( sdss ; * ? ? ?
* ) , have revealed a complex hierarchical network of structure , called the cosmic web , composed of clusters , filaments , sheets , and voids ( e.g. * ? ? ?
* ) . in the current paradigm of galaxy formation ,.
Please generate the next two sentences of the article | these structures arise from the linear growth of gaussian density fluctuations in a nearly homogeneous early universe .
dark matter tends to flow out of the voids , accretes onto the sheets , collapses to the filaments , and finally accumulates onto the clusters at the intersections of the filaments . due to the accretion history of the universe , |
6,769 | Suppose that you have an abstract for a scientific paper: topological surgery occurs in natural phenomena where two points are selected and attracting or repelling forces are applied .
the two points are connected via an invisible ` thread ' . in order to model topologically such phenomena
we introduce dynamics in 1- , 2- and 3-dimensional topological surgery , by means of attracting or repelling forces between two selected points in the manifold , and we address examples .
we also introduce the notions of solid 1- and 2-dimensional topological surgery , and of truncated 1- , 2- and 3-dimensional topological surgery , which are more appropriate for modelling natural processes . on the theoretical level , these new notions allow to visualize 3-dimensional surgery and to connect surgeries in different dimensions . we hope that through this study , topology and dynamics of many natural phenomena as well as topological surgery may now be better understood .
`` = 1 '' .
And you have already written the first three sentences of the full article: the aim of this study is to draw a connection between topological surgery in dimensions 1 , 2 and 3 and many natural phenomena . for this
we introduce new theoretical concepts which allow to explain the topology of such phenomena via surgery and also to connect topological surgeries in different dimensions .
the new concepts are the introduction of forces , attracting or repelling , in the process of surgery , the notion of solid 1- and 2-dimensional surgery and the notion of truncated 1- , 2- and 3-dimensional surgery ..
Please generate the next two sentences of the article | topological surgery is a technique used for changing the homeomorphism type of a topological manifold , thus for creating new manifolds out of known ones .
a homeomorphism between two @xmath0-manifolds is a continuous bijection , such that the inverse map is also continuous . |
6,770 | Suppose that you have an abstract for a scientific paper: the formalism of frozen - in vortex lines for two - dimensional ( 2d ) flows in ideal incompressible electron magnetohydrodynamics ( emhd ) is formulated . a localized approximation for nonlinear dynamics of two close sheets of the generalized vorticity
is suggested and its integrability by the hodograph method is demonstrated . .
And you have already written the first three sentences of the full article: this work is devoted to analytical study of ideal incompressible emhd flows ( see , e.g. , @xcite and references therein about emhd and its applications ) .
our primary goal here is to consider a simplified 1d problem that has many similar qualitative properties with the problem about attractive interaction of two distributed currents in 2d ideal emhd , that was numerically simulated recently with a high resolution @xcite .
more precisely , we introduce and partially analyse local approximations for particular class of the 2d ideal emhd flows , that are reduced in mathematical sense to dynamics of a single or few 1d objects , the vortex lines . the most interesting result of present work is the demonstration of exact solvability by the known hodograph method of long - scale dynamics in the unstable vortex structure constituted by two nearly anti - parallel sheets of the generalized vorticity in 2d ideal emhd ..
Please generate the next two sentences of the article | as known , the emhd model approximately describes dynamics of the low - inertial electron component of plasma in situations when the heavy ion component is almost motionless and serves just to provide a neutralizing background for electrically charged electron fluid and to keep a constant concentration @xmath0 of the electrons .
the ( divergence - free in this case ) electric current @xmath1 creates the quasi - stationary magnetic field , @xmath2 which contributes to the generalized electron vorticity , @xmath3 the most simple way how to derive the ideal emhd equation of motion is just to use the well known fact that the generalized vorticity in an ideal homogeneous fluid is frozen - in , @xmath4.\ ] ] as the result , the corresponding equation of motion can be represented in the remarkable form @xmath5,\ ] ] where the hamiltonian functional of ideal incompressible emhd in the fourier representation is given by the expression @xmath6 here @xmath7 or @xmath8 depending on dimensionality of the problem and the electron inertial length @xmath9 is introduced . |
6,771 | Suppose that you have an abstract for a scientific paper: be / x - ray binary systems exhibit both periodic ( type i ) x - ray outbursts and giant ( type ii ) outbursts , whose origin has remained elusive .
we suggest that type ii x - ray outbursts occur when a highly misaligned decretion disk around the be star becomes eccentric , allowing the compact object companion to capture a large amount of material at periastron . using 3d smoothed particle hydrodynamics simulations we model the long term evolution of a representative be / x - ray binary system .
we find that periodic ( type i ) x - ray outbursts occur when the neutron star is close to periastron for all disk inclinations .
type ii outbursts occur for large misalignment angles and are associated with eccentricity growth that occurs on a timescale of about 10 orbital periods .
mass capture from the eccentric decretion disk results in an accretion disk around the neutron star whose estimated viscous time is long enough to explain the extended duration of type ii outbursts .
previous studies suggested that the outbursts are caused by a warped disk but our results suggest that this is not sufficient , the disk must be both highly misaligned and eccentric to initiate a type ii accretion event .
[ firstpage ] .
And you have already written the first three sentences of the full article: be stars are early main - sequence stars which have shown h@xmath0 emission at least once ( e.g. * ? ? ?
they are rapidly rotating close to their break up velocity @xcite .
the stars are surrounded by decretion disks @xcite , formed from ejected material that settles into a keplerian disk and spreads outwards through viscous diffusion @xcite ..
Please generate the next two sentences of the article | the mechanism for ejection is uncertain ( rotation alone is insufficient ) , with magnetic fields ( e.g. * ? ? ?
* ; * ? ? ? |
6,772 | Suppose that you have an abstract for a scientific paper: we investigate the recently quantified misalignment of @xmath0 between the 3-d geometry of stereoscopically triangulated coronal loops observed with stereo / euvi ( in four active regions ) and theoretical ( potential or nonlinear force - free ) magnetic field models extrapolated from photospheric magnetograms .
we develop an efficient method of bootstrapping the coronal magnetic field by forward - fitting a parameterized potential field model to the stereo - observed loops .
the potential field model consists of a number of unipolar magnetic charges that are parameterized by decomposing a photospheric magnetogram from mdi .
the forward - fitting method yields a best - fit magnetic field model with a reduced misalignment of @xmath1 .
we evaluate also stereoscopic measurement errors and find a contribution of @xmath2 , which constrains the residual misalignment to @xmath3 , which is likely due to the nonpotentiality of the active regions .
the residual misalignment angle @xmath4 of the potential field due to nonpotentiality is found to correlate with the soft x - ray flux of the active region , which implies a relationship between electric currents and plasma heating . .
And you have already written the first three sentences of the full article: the stereo mission provides us an unprecedented view of the solar corona , enabling us for the first time to fully constrain the three - dimensional ( 3-d ) geometry of the coronal magnetic field .
stereoscopic triangulation of coronal loops has been conducted at small stereo spacecraft separation angles ( @xmath5 ) , for several active regions observed with stereo a(head ) and b(ehind ) in april and may 2007 ( aschwanden et al . 2008a , b ; 2009 ) .
the reconstructed 3-d geometry of stereo - observed coronal loops has been compared with theoretical magnetic field models based on extrapolations from photospheric magnetograms , using nonlinear force - free field ( nlfff ) models ( derosa et al ..
Please generate the next two sentences of the article | 2009 ) , as well as potential and stretched potential field models ( sandman et al .
2009 ) , but surprisingly it turned out that the two types of magnetic field lines exhibited an average misalignment angle of @xmath6 , regardless of what type of theoretical magnetic field model was used . from this dilemma |
6,773 | Suppose that you have an abstract for a scientific paper: the structural , transport , magnetic and optical properties of the double perovskite @xmath0crwo@xmath1 with @xmath2 have been studied . by varying the alkaline earth ion on the @xmath3 site ,
the influence of steric effects on the curie temperature @xmath4 and the saturation magnetization has been determined .
a maximum @xmath5k was found for sr@xmath6crwo@xmath1 having an almost undistorted perovskite structure with a tolerance factor @xmath7 . for ca@xmath6crwo@xmath1 and ba@xmath6crwo@xmath1 structural changes result in a strong reduction of @xmath4 .
our study strongly suggests that for the double perovskites in general an optimum @xmath4 is achieved only for @xmath8 , that is , for an undistorted perovskite structure .
electron doping in sr@xmath6crwo@xmath1 by a partial substitution of sr@xmath9 by la@xmath10 was found to reduce both @xmath4 and the saturation magnetization @xmath11 .
the reduction of @xmath11 could be attributed both to band structure effects and the cr / w antisites induced by doping .
band structure calculations for sr@xmath6crwo@xmath1 predict an energy gap in the spin - up band , but a finite density of states for the spin - down band .
the predictions of the band structure calculation are consistent with our optical measurements .
our experimental results support the presence of a kinetic energy driven mechanism in @xmath0crwo@xmath1 , where ferromagnetism is stabilized by a hybridization of states of the nonmagnetic w - site positioned in between the high spin cr - sites . .
And you have already written the first three sentences of the full article: the investigation of ordered double perovskite materials @xmath12 with @xmath3 an alkaline earth such as sr , ba , or ca and @xmath13 two different transition metals has been strongly stimulated by the discovery of a large room temperature magnetoresistive effect at low magnetic fields in sr@xmath6femoo@xmath1 @xcite .
the fact that the double perovskites seem to be ferromagnetic metals with high curie temperatures @xmath4 of up to 635k @xcite and apparently have highly spin polarized conduction band makes these materials interesting for applications in spintronic devices such as magnetic tunnel junctions or low - field magnetoresistive sensors @xcite . however , the double perovskites are also of fundamental interest since both their basic physics and materials aspects are not well understood .
it is evident that intensive research has been dedicated to both the variation of the metallic / magnetic ions on the @xmath14- and @xmath15-site as well as electron doping studies , where the divalent alkaline earth ions on the @xmath3-site are partially replaced by a trivalent rare earth ion such as la , in order to understand the electronic structure and the magnetic exchange in the double perovskites in detail ..
Please generate the next two sentences of the article | furthermore , these studies aimed for the tailoring and optimization of the magnetic properties of the double perovskites for their use in magnetoelectronic devices such as spin valves , magnetic information storage systems , or as sources for spin polarized electrons in spintronics . here , important aspects are the achievement of sufficiently high values for @xmath4 and the spin polarization to allow for the operation of potential devices at room temperature . along this line ,
in the compound sr@xmath6crreo@xmath1 a curie temperature of @xmath16k has been obtained @xcite . |
6,774 | Suppose that you have an abstract for a scientific paper: production of the doubly strange @xmath0 baryon in heavy - ion collisions at energies is studied in a relativistic transport model that includes perturbatively the strangeness - exchange reactions @xmath1 and @xmath2 . taking the cross sections for these reactions from the predictions of a hadronic model , we find that the @xmath0 yield is about @xmath3 in central collisions of @xmath4ni + @xmath5ni at @xmath6 .
the @xmath0 yield is further found to be more sensitive to the magnitude of the cross sections for strangeness - exchange reactions than to the medium effects due to modified kaon properties .
we have also made predictions for @xmath0 production in au+au collisions at energies from @xmath7 to @xmath8 gev / nucleon . .
And you have already written the first three sentences of the full article: production of the doubly strange baryon @xmath0 has been studied in heavy ion collisions at various energies . for ultrarelativistic energies at sps , the measured @xmath0 abundance
is significantly enhanced compared to that expected from initial nucleon - nucleon collisions @xcite .
explanations for this enhancement include exotic mechanisms due to the formation of the quark - gluon plasma , topological defects , and color ropes as well as more conventional processes of strangeness - exchange reactions such as @xmath9 and @xmath2 spal01 . in the latter case.
Please generate the next two sentences of the article | , the experimental data can , however , only be explained if a relatively high dense hadronic matter exists in these collisions .
observations of @xmath0 production at lower energies at the ags , e.g. , au+au collisions at 6 agev @xcite , have also been reported recently , and the measured yield is comparable to the predictions from the transport model based on strangeness - exchange reactions @xcite . |
6,775 | Suppose that you have an abstract for a scientific paper: the exact exchange - correlation ( xc ) potential in time - dependent density - functional theory ( tddft ) is known to develop steps and discontinuities upon change of the particle number in spatially confined regions or isolated subsystems .
we demonstrate that the self - interaction corrected adiabatic local - density approximation for the xc potential has this property , using the example of electron loss of a model quantum well system .
we then study the influence of the xc potential discontinuity in a real - time simulation of a dissociation process of an asymmetric double quantum well system , and show that it dramatically affects the population of the resulting isolated single quantum wells .
this indicates the importance of a proper account of the discontinuities in tddft descriptions of ionization , dissociation or charge transfer processes . .
And you have already written the first three sentences of the full article: the most widely used family of exchange - correlation ( xc ) functionals in density - functional theory ( dft ) @xcite , the local density approximation ( lda ) and its gradient - corrected semilocal relatives , has been largely responsible for the enormous popularity of the theory for electronic - structure calculations . despite many successes , there are important properties of the exact xc potential that are missed by the lda and many other popular approximations . in this paper , we shall deal with one such property , namely the discontinuity of the xc potential upon change of particle number @xcite .
it is well known that the exact xc energy functional must vary linearly as a function of the total number of particles @xmath0 , displaying a derivative discontinuity every time the system passes through an integral value of @xmath0 @xcite .
the delocalization error @xcite , however , causes the lda to predict a nonlinear curvature for the change of xc energy with particle number ..
Please generate the next two sentences of the article | this has important practical consequences , for instance leading to a description of molecular dissociation where the resulting isolated atoms end up with unphysical fractional electron numbers .
therefore , attempts to model molecular dissociation processes , or any phenomenon that is associated with the transport of charges between well - separated spatial regions or subsystems , must take the discontinuity of the xc functional into account @xcite . in the framework of time - dependent density - functional theory ( tddft ) @xcite , |
6,776 | Suppose that you have an abstract for a scientific paper: we investigate an anisotropic model of superconductors in the einstein - maxwell - dilaton theory with a charged scalar field .
it is found that the critical temperature decreases as the anisotropy becomes large .
we then estimate the energy gap of the superconductor , and find that the ratio of the energy gap to the critical temperature increases as the anisotropy increases and so it is larger than that in the isotropic case .
we also find that peudogap appears due to the anisotropy . .
And you have already written the first three sentences of the full article: the ads / cft correspondence @xcite gives new insight for understanding strongly coupled gauge theories or strongly correlated condensed matter systems . in particular , high temperature superconductors in the framework of the ads / cft correspondence attract much attention .
the simple model of holographic superconductors initiated in @xcite has been extended into more realistic models with inhomogeneity @xcite .
anisotropic models of superconductors also have been investigated in the context of p - wave superconductors , where a non - abelian gauge field condenses in the superconducting state @xcite ..
Please generate the next two sentences of the article | since real - world superconductors exhibit various types of anisotropy , it will be valuable to consider other models of anisotropic holographic superconductors .
we then consider in this paper the holographic model in the einstein - maxwell - dilaton theory analyzed in @xcite , where the bulk solution corresponding to the normal state was constructed . |
6,777 | Suppose that you have an abstract for a scientific paper: the star detector at rhic , due to its large uniform acceptance and excellent particle identification capabilities , has measured a variety of hadron species ( @xmath0 , @xmath1 , @xmath2 , @xmath3 , @xmath4 , @xmath5 , @xmath6 , @xmath7 , @xmath8 ) produced in au+au collisions at @xmath9 , 11.5 , 27 and 39 gev .
these data are part of the beam energy scan ( bes ) program at rhic and provide an opportunity to measure the yields and transverse momentum spectra ( @xmath10 ) of the particles produced in the collisions .
the corresponding measurements allow to study the freeze - out properties and dynamics of heavy ion collisions .
a statistical thermal model analysis of particle production in bes energies in both grand canonical and strangeness canonical ensembles , is used to extract the chemical freeze - out parameters .
the @xmath10 spectra , particle ratios , and the energy and centrality dependence of freeze - out parameters determined from the thermal fit of particle ratios are discussed . .
And you have already written the first three sentences of the full article: relativistic heavy - ion collisions provide the opportunity to study strongly interacting nuclear matter at different thermodynamic conditions .
quantum chromodynamics ( qcd ) , a fundamental theory to describe the interactions of quarks and gluons , has anticipated the transition from hadronic matter to a new state of matter called quark - gluon plasma ( qgp ) [ 1 ] phase at high temperature and high energy density ( @xmath11 gev/@xmath12 ) .
the qcd phase diagram is characterized by the temperature ( t ) and the baryon chemical potential ( @xmath13 ) or the ( net ) baryon density ( @xmath14 ) , and it contains the information about the phase boundary that separates the qgp and hadronic phases [ 2,3 ] ..
Please generate the next two sentences of the article | finite temperature lattice qcd calculations [ 4 ] predict a cross - over from hadronic to qgp phase at vanishing baryon chemical potential and large t while several qcd - based calculations [ 5 ] show that at lower t and @xmath15 a first - order phase transition may take place .
the point in the qcd phase diagram , where the first order phase transition ends would be the qcd critical point [ 6 ] . |
6,778 | Suppose that you have an abstract for a scientific paper: the atomic register is certainly the most basic object of computing science .
its implementation on top of an @xmath0-process asynchronous message - passing system has received a lot of attention .
it has been shown that @xmath1 ( where @xmath2 is the maximal number of processes that may crash ) is a necessary and sufficient requirement to build an atomic register on top of a crash - prone asynchronous message - passing system .
considering such a context , this paper visits the notion of a fast implementation of an atomic register , and presents a new time - efficient asynchronous algorithm .
its time - efficiency is measured according to two different underlying synchrony assumptions .
whatever this assumption , a write operation always costs a round - trip delay , while a read operation costs always a round - trip delay in favorable circumstances ( intuitively , when it is not concurrent with a write ) . when designing this algorithm , the design spirit was to be as close as possible to the one of the famous abd algorithm ( proposed by attiya , bar - noy , and dolev ) . + + *
keywords * : asynchronous message - passing system , atomic read / write register , concurrency , fast operation , process crash failure , synchronous behavior , time - efficient operation . .
And you have already written the first three sentences of the full article: since sumer time @xcite , and much later turing s machine tape @xcite , read / write objects are certainly the most basic memory - based communication objects .
such an object , usually called a _ register _ , provides its users ( processes ) with a write operation which defines the new value of the register , and a read operation which returns the value of the register . when considering sequential computing , registers are universal in the sense that they allow to solve any problem that can be solved @xcite .
[ [ register - in - message - passing - systems ] ] register in message - passing systems + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + in a message - passing system , the computing entities communicate only by sending and receiving messages transmitted through a communication network . hence ,.
Please generate the next two sentences of the article | in such a system , a register is not a communication object given for free , but constitutes a communication abstraction which must be built with the help of the communication network and the local memories of the processes .
several types of registers can be defined according to which processes are allowed to read or write it , and the quality ( semantics ) of the value returned by each read operation . |
6,779 | Suppose that you have an abstract for a scientific paper: the discovery of neutrino oscillations provides a solid evidence for nonzero neutrino masses and leptonic mixing .
the fact that neutrino masses are so tiny constitutes a puzzling problem in particle physics . from the theoretical viewpoint
, the smallness of neutrino masses can be elegantly explained through the seesaw mechanism .
another challenging issue for particle physics and cosmology is the explanation of the matter - antimatter asymmetry observed in nature . among the viable mechanisms ,
leptogenesis is a simple and well - motivated framework . in this talk
we briefly review these aspects , making emphasis on the possibility of linking neutrino physics to the cosmological baryon asymmetry originated from leptogenesis . .
And you have already written the first three sentences of the full article: neutrino experiments have provided a convincing evidence that neutrinos oscillate among different flavors .
the experimental data collected over more than a decade imply that at least two neutrinos have nonzero mass and that there is mixing in the lepton sector , in analogy to the cabibbo - kobayashi - maskawa ( ckm ) mixing in the quark sector .
yet neutrinos have surprised us since their properties are quite different from those of charged fermions ..
Please generate the next two sentences of the article | table 1 reports our present knowledge of neutrino mass and mixing parameters obtained by the analysis of the global @xmath0 oscillation data .
@xcite although neutrino oscillation experiments are not sensitive to the absolute neutrino mass scale , direct kinematical searches and cosmological bounds set @xmath1 ev . thus neutrinos are at least six orders of magnitude lighter than the other fermions in the standard model ( sm ) . |
6,780 | Suppose that you have an abstract for a scientific paper: the steady - state of a generalized coagulation - decoagulation model on a one - dimensional lattice with reflecting boundaries is studied using a matrix - product approach .
it is shown that the quadratic algebra of the model has a four - dimensional representation provided that some constraints on the microscopic reaction rates are fulfilled .
the dynamics of a product shock measure with two shock fronts , generated by the hamiltonian of this model , is also studied .
it turns out that the shock fronts move on the lattice as two simple random walkers which repel each other provided that the same constraints on the microscopic reaction rates are satisfied . .
And you have already written the first three sentences of the full article: the study of microscopic structure and dynamics of traveling wave solutions in multi - species one - dimensional stochastic systems has attracted people s attention in this field considerably in recent years @xcite-@xcite .
for instance , the microscopic dynamics of shocks are studied for three families of single - species one - dimensional reaction - diffusion systems with open boundaries and nearest - neighbors interactions which include the partially asymmetric simple exclusion process ( pasep ) , the branching - coalescing random walk ( bcrw ) and the asymmetric kawasaki - glauber process ( akgp ) @xcite .
it has been shown that in all three systems the time evolution of a product shock measure with a single shock front is equivalent to that of a simple random walker on a finite lattice with homogeneous hopping rates in the bulk and special reflection rates at the boundaries , provided that some constraints on the microscopic reaction rates are fulfilled ..
Please generate the next two sentences of the article | the steady - states of these three systems can be essentially written as a linear superposition of such product shock measures .
on the other hand , the steady - states of these systems can be obtained using the matrix - product formulation @xcite in which the steady - state weights are written in terms of the product of non - commuting operators which satisfy a quadratic algebra ( for a recent review of this approach see @xcite ) . |
6,781 | Suppose that you have an abstract for a scientific paper: we show in single top quark production that the spin of the top quark is correlated with the direction of the @xmath0-type quark in the event . for single top production in the @xmath1 channel ,
the @xmath0-type quark comes dominantly from the antiproton at the tevatron , whereas for the @xmath2-gluon fusion channel the spectator jet is the @xmath0-type quark the majority of the time at this machine .
our results are that 98% of the top quarks from the @xmath3 process have their spins in the antiproton direction , and 96% of the top quarks in the @xmath2-gluon fusion process have their spins in the spectator jet direction .
we also compare with the more traditional , but less effective , helicity basis .
the direction of the top quark spin is reflected in angular correlations in its decay products . .
And you have already written the first three sentences of the full article: the single top quark production processes are of great importance at hadron colliders since they allow a direct measurement of the coupling of the @xmath2-boson to the top quark _
i.e. _ the ckm matrix element @xmath4 .
these processes can also be used to search for anomalous couplings of the top quark . with a mass in the neighborhood of 175 gev@xcite ,.
Please generate the next two sentences of the article | the top quark is by far the heaviest of the known quarks . as a consequence
, the electroweak decay of the top quark proceeds so rapidly that toponium bound states and @xmath5 mesons do not have time to form @xcite and the decay products of the top quark are correlated with its spin @xcite . |
6,782 | Suppose that you have an abstract for a scientific paper: we present the discovery of a brown dwarf companion to the debris disk host star hr 2562 .
this object , discovered with the gemini planet imager ( gpi ) , has a projected separation of [email protected] au ( @xmath1 ) from the star . with the high astrometric precision afforded by gpi , we have confirmed common proper motion of hr 2562b with the star with only a month time baseline between observations to more than @xmath2 .
spectral data in @xmath3 , @xmath4 , and @xmath5 bands show morphological similarity to l / t transition objects .
we assign a spectral type of l7@xmath03 to hr 2562b , and derive a luminosity of @xmath6(l@xmath7/l@xmath8)[email protected] , corresponding to a mass of 30@xmath015 m@xmath9 from evolutionary models at an estimated age of the system of 300900 myr .
although the uncertainty in the age of the host star is significant , the spectra and photometry exhibit several indications of youth for hr 2562b .
the source has a position angle consistent with an orbit in the same plane as the debris disk recently resolved with _
herschel_. additionally , it appears to be interior to the debris disk .
though the extent of the inner hole is currently too uncertain to place limits on the mass of hr 2562b , future observations of the disk with higher spatial resolution may be able to provide mass constraints .
this is the first brown dwarf - mass object found to reside in the inner hole of a debris disk , offering the opportunity to search for evidence of formation above the deuterium burning limit in a circumstellar disk . .
And you have already written the first three sentences of the full article: there is considerable interest in determining whether jovian planets on wide orbits represents a continuum that extends to brown dwarf masses , or whether there is a strong cutoff in the number of companions as a function of mass ( e.g. , * ? ? ?
this relates to possible formation pathways for substellar companions : either companions form within a circumstellar disk and reach a mass above the deuterium burning limit ( e.g. , @xcite ) or via cloud fragmentation , as in binary systems with a high mass ratio ( @xmath10 , @xcite ) .
population statistics from direct imaging provide essential observational parameters to test formation history . from numerous surveys , only a handful of imaged substellar companions are @xmath11100 au from their host stars ..
Please generate the next two sentences of the article | in particular , this separation regime has shown a lack of brown dwarfs with @xmath12 ( the `` brown - dwarf desert '' , e.g. , @xcite ) around stars with m@xmath13m@xmath14 .
however , this parameter space has recently begun to be populated by direct imaging ( e.g. , * ? ? ? |
6,783 | Suppose that you have an abstract for a scientific paper: we construct nontopological solitonic solutions in ( 3 + 1)-dimensional minkowski spacetime carrying a conserved global @xmath0 charge and nonvanishing angular momentum in a supersymmetric extension of the standard model with low - energy , gauge - mediated symmetry breaking . .
And you have already written the first three sentences of the full article: q - balls are nontopological solitonic solutions of a self - interacting complex scalar field theory carrying a conserved global @xmath0 charge
. introduced by coleman in 1985 @xcite , their properties have been extensively studied since then @xcite .
if on the one hand , volkov and whnert @xcite showed , in the context of some theories with nonrenormalizable scalar potentials , that there exist particular q - ball configurations possessing nonvanishing angular momentum , now known as `` spinning q - balls '' , on the other hand , dvali , kusenko and shaposhnikov @xcite proved in the framework of supersymmetric extensions of the standard model that gauge - singlet combinations of squarks and sleptons corresponding to some flat direction of the supersymmetric potential can give rise to q - balls whose charge @xmath1 is some combination of baryon and lepton numbers ..
Please generate the next two sentences of the article | the attractive feature of theses `` supersymmetric q - balls '' is that they could represent the dark matter component of the universe @xcite ( for reviews on dark matter see , e.g. , ref .
@xcite ) . motivated by this fact , experimental searches for q - balls are being carried out @xcite , although no compelling evidence for their existence has been reported so far . |
6,784 | Suppose that you have an abstract for a scientific paper: background : : : models based on using perturbative polarization corrections and mean - field blocking approximation give conflicting results for masses of odd nuclei .
purpose : : : systematically investigate the polarization and mean - field models , implemented within self - consistent approaches that use identical interactions and model spaces , so as to find reasons for the conflicts between them .
methods : : : for density - dependent interactions and with pairing correlations included , we derive and study links between the mean - field and polarization results obtained for energies of odd nuclei .
we also identify and discuss differences between the polarization - correction and full particle - vibration - coupling ( pvc ) models .
numerical calculations are performed for the mean - field ground - state properties of deformed odd nuclei and then compared to the polarization corrections determined by using the approach that conserves spherical symmetry .
results : : : we have identified and numerically evaluated self - interaction ( si ) energies that are at the origin of different results obtained within the mean - field and polarization - correction approaches .
conclusions : : : mean - field energies of odd nuclei are polluted by the si energies , and this makes them different from those obtained by using polarization - correction methods .
a comparison of both approaches allows for the identification and determination of the si terms , which then can be calculated and removed from the mean - field results , giving the self - interaction - free energies .
the simplest deformed mean - field approach that does not break parity symmetry is unable to reproduce full pvc effects . .
And you have already written the first three sentences of the full article: the perturbative particle - vibration - coupling ( pvc ) model for odd - particle - number nuclei emerges naturally from the self - consistent green s function theory @xcite .
it describes the polarization of the nucleus when one particle is added or removed @xcite , and its results can , in principle , be directly compared against experimental data .
as used in nuclear physics , the perturbative pvc method employs one - particle or one - hole states ( or one - quasiparticle states ) coupled with the rpa or qrpa excitations of an even - even reference nucleus , and the residual nucleon - nucleon interaction that mixes these states at second - order perturbation theory ..
Please generate the next two sentences of the article | numerous pvc calculations of increasing level of sophistication have already been performed , see , e.g. , refs .
@xcite and excellent recent reviews thereof available in refs . |
6,785 | Suppose that you have an abstract for a scientific paper: the collective raman cooling of trapped one- and two - component fermi gases is considered .
we obtain the quantum master equation that describes the laser cooling in the _ festina lente _ regime , for which the heating due to photon reabsorption can be neglected .
for the two - component case the collisional processes are described within the formalism of quantum boltzmann master equation .
the inhibition of the spontaneous emission can be overcome by properly adjusting the spontaneous raman rate during the cooling .
our numerical results based in monte carlo simulations of the corresponding rate equations , show that three - dimensional temperatures of the order of @xmath0 @xmath1 ( single - component ) and @xmath2 @xmath1 ( two - component ) can be achieved .
we investigate the statistical properties of the equilibrium distribution of the laser - cooled gas , showing that the number fluctuations are enhanced compared with the thermal distribution close to the fermi surface .
finally , we analyze the heating related to the background losses , concluding that our laser - cooling scheme should maintain the temperature of the gas without significant additional losses . .
And you have already written the first three sentences of the full article: the achievement of bose - einstein condensation ( bec ) @xcite in trapped dilute atomic gases has stimulated a large interest in the physics of ultracold gases , both bosonic and fermionic ones .
related with the latter , similar cooling methods as those employed to reach bec have been recently employed to accomplish a degenerate fermi gas , i.e. a fermi gas with temperature @xmath3 below the fermi temperature ( @xmath1 ) @xcite . for @xmath4
the fermi pressure becomes noticeable , and as a consequence the fermi cloud becomes significantly broader than a bec under the same temperature ..
Please generate the next two sentences of the article | additionally , for temperatures below a critical one , @xmath5 , the system should undergo a bardeen - cooper - schrieffer ( bcs ) transition @xcite .
when this occurs the system becomes superfluid , due to the cooper pairing of particles near the fermi surface . |
6,786 | Suppose that you have an abstract for a scientific paper: in order to attain the requisite sensitivity for lisa - a joint space mission of the esa and nasa- the laser frequency noise must be suppressed below the secondary noises such as the optical path noise , acceleration noise etc . by combining six
appropriately time - delayed data streams containing fractional doppler shifts - a technique called time delay interferometry ( tdi ) - the laser frequency noise may be adequately suppressed .
we consider the general model of lisa where the armlengths vary with time , so that second generation tdi are relevant .
however , we must envisage the possibility , that not all the optical links of lisa will be operating at all times , and therefore , we here consider the case of lisa operating with two arms only . as shown earlier in the literature ,
obtaining even approximate solutions of tdi to the general problem is very difficult . since here
only four optical links are relevant , the algebraic problem simplifies considerably .
we are then able to exhibit a large number of solutions ( from mathematical point of view an infinite number ) and further present an algorithm to generate these solutions . .
And you have already written the first three sentences of the full article: lisa - laser interferometric space antenna - is a proposed esa - nasa mission which will use coherent laser beams exchanged between three identical spacecraft forming a giant ( almost ) equilateral triangle of side @xmath0 kilometres to observe and detect low frequency cosmic gw @xcite .
laser frequency noise dominates the other secondary noises , such as optical path noise , acceleration noise by 7 or 8 orders of magnitude , and must be removed if lisa is to achieve the required sensitivity of @xmath1 , where @xmath2 is the metric perturbation caused by a gravitational wave . in lisa , six data streams arise from the exchange of laser beams between the three spacecraft approximately 5 million km apart .
these six streams produce redundancy in the data which can be used to suppress the laser frequency noise by the technique called time - delay interferometry ( tdi ) in which the six data streams are combined with appropriate time - delays @xcite ..
Please generate the next two sentences of the article | a mathematical foundation for the tdi problem for the static lisa was given in @xcite , where it was shown that the data combinations cancelling laser frequency noise formed the _ module of syzygies _ over the polynomial ring of time - delay operators .
for the static lisa , the polynomial ring was in three variables and also commutative . |
6,787 | Suppose that you have an abstract for a scientific paper: we show that for a big class of contact manifolds the groups of order @xmath0 invariants ( with values in an arbitrary abelian group ) of legendrian , of transverse , and of framed knots are canonically isomorphic .
on the other hand for an arbitrary cooriented contact structure on @xmath1 with the nonzero euler class of the contact bundle we construct examples of legendrian homotopic legendrian knots @xmath2 and @xmath3 such that they realize isotopic framed knots but can be distinguished by finite order invariants of legendrian knots in @xmath1 .
we construct similar examples for a big class of contact manifolds @xmath4 such that @xmath4 is a total space of a locally trivial @xmath5-fibration over a nonorientable surface .
we show that in some of these examples the complements of @xmath2 and of @xmath3 are overtwisted . in this paper @xmath6
is a not necessarily torsion free abelian group , and @xmath4 is a not necessarily compact connected orientable three dimensional riemannian manifold . .
And you have already written the first three sentences of the full article: a _ contact structure _ on a three - dimensional manifold @xmath4 is a smooth field @xmath7 of tangent two - dimensional planes , locally defined as a kernel of a differential @xmath8-form @xmath9 with non - vanishing @xmath10 .
a contact structure is _ cooriented _ if the two - dimensional planes defining the contact structure are continuously cooriented ( transversally oriented ) .
a contact structure is _ parallelized _ if the two dimensional vector bundle @xmath11 over @xmath4 is trivialized ..
Please generate the next two sentences of the article | a contact structure @xmath12 on a manifold @xmath4 is said to be _ overtwisted _ if there exists a @xmath13-disk @xmath14 embedded into @xmath4 such that the boundary @xmath15 is tangent to @xmath12 while the disk @xmath14 is transverse to @xmath12 along @xmath15 .
not overtwisted contact structures are called _ |
6,788 | Suppose that you have an abstract for a scientific paper: neutrino - cooled hyperaccretion disks around stellar mass black holes are plausible candidates for the central engine of gamma - ray bursts .
we calculate the one - dimensional structure and the annihilation luminosity of such disks .
the neutrino optical depth is of crucial importance in determining the neutrino cooling rate and is in turn dependent on the electron fraction , the free nucleon fraction , and the electron degeneracy , with given density and temperature of the disk matter .
we construct a bridging formula for the electron fraction that works for various neutrino optical depths , and give exact definitions for the free proton fraction and free neutron fraction .
we show that the electron degeneracy has important effects in the sense that it enlarges the absorption optical depth for neutrinos , and it along with the neutronization processes favored by high temperature cause the electron fraction to drop to be below 0.1 in the inner region of the disk .
the resulting neutrino annihilation luminosity is considerably reduced comparing with that obtained in previous works where the electron degeneracy was not considered and the electron fraction was simply taken to be 0.5 , but it is still likely to be adequate for gamma - ray bursts , and it is ejected mainly from the inner region of the disk and has an anisotropic distribution . .
And you have already written the first three sentences of the full article: theoretical models for gamma - ray bursts ( grbs ) can be divided into two categories : those named fireball models that treat the shock interaction of relativistic outflows and production of gamma rays and afterglows in other wavelengths ( see , e.g. , mszros 2002 and zhang & mszros 2004 for reviews ) , and those that explore the central engine of the fireball , i.e. , the energy source of relativistic outflows .
most popular models in the latter category are in common invoking a stellar - mass black hole accreting with a hypercritical rate , of the order of 1 .
the main problem in these models is how to convert some fraction of the released gravitational energy of the accreted matter into a relativistic outflow , creating an explosion with energy @xmath0 @xmath1-@xmath2 ergs ( depending on whether emission is isotropic or it is beamed ) ..
Please generate the next two sentences of the article | two mechanisms have been proposed to tackle this problem : the neutrino emission and annihilation , and the energy extraction from the accretion disk and/or the black hole via magnetohydrodynamical processes ( see , e.g. , popham et al . 1999 and di matteo et al .
2002 for references ) . |
6,789 | Suppose that you have an abstract for a scientific paper: we consider linear iterated function systems ( ifs ) with a constant contraction ratio in the plane for which the `` overlap set '' @xmath0 is finite , and which are `` invertible '' on the attractor @xmath1 , in the sense that there is a continuous surjection @xmath2 whose inverse branches are the contractions of the ifs .
the overlap set is the critical set in the sense that @xmath3 is not a local homeomorphism precisely at @xmath0 .
we suppose also that there is a rational function @xmath4 with the julia set @xmath5 such that @xmath6 and @xmath7 are conjugate . we prove that if @xmath1 has bounded turning and @xmath4 has no parabolic cycles
, then the conjugacy is quasisymmetric .
this result is applied to some specific examples including an uncountable family .
our main focus is on the family of ifs @xmath8 where @xmath9 is a complex parameter in the unit disk , such that its attractor @xmath10 is a dendrite , which happens whenever @xmath0 is a singleton . c. bandt observed that a simple modification of such an ifs ( without changing the attractor ) is invertible and gives rise to a quadratic - like map @xmath11 on @xmath10 .
if the ifs is post - critically finite , then a result of a. kameyama shows that there is a quadratic map @xmath12 , with the julia set @xmath13 such that @xmath14 and @xmath15 are conjugate .
we prove that this conjugacy is quasisymmetric and obtain partial results in the general ( not post - critically finite ) case . .
And you have already written the first three sentences of the full article: for @xmath16 in the open unit disk @xmath17 consider the compact set @xmath18 given by @xmath19 it is the attractor for the iterated function system ( ifs ) @xmath20 , where @xmath21 , that is , @xmath10 is the unique non - empty compact set such that @xmath22 , see @xcite .
the connectedness locus @xmath23 was introduced in @xcite and studied by several authors , see @xcite in particular .
there is the same dichotomy as for julia sets @xmath13 of quadratic maps @xmath24 : the attractor @xmath10 is either connected or totally disconnected ..
Please generate the next two sentences of the article | it is well - known that @xmath10 is connected if and only if @xmath25 it follows that @xmath26 has a characterization as the set of zeros of @xmath27 power series : @xmath28 figure 1 shows the part of @xmath26 in @xmath29 ( the set @xmath26 is symmetric with respect to both axes , and all @xmath30 , with @xmath31 , are known to be in @xmath26 ) .
bousch @xcite proved that @xmath26 is connected and locally connected . here |
6,790 | Suppose that you have an abstract for a scientific paper: the icecube neutrino observatory pursues a follow - up program selecting interesting neutrino events in real - time and issuing alerts for electromagnetic follow - up observations . in march 2012 ,
the most significant neutrino alert during the first three years of operation was issued by icecube . in the follow - up observations performed by the palomar transient factory ( ptf ) ,
a type iin supernova ( sn ) ptf12csy was found away from the neutrino alert direction , with an error radius of .
it has a redshift of @xmath0 , corresponding to a luminosity distance of about and the pan - starrs1 survey shows that its explosion time was at least 158 days ( in host galaxy rest frame ) before the neutrino alert , so that a causal connection is unlikely .
the _ a posteriori _ significance of the chance detection of both the neutrinos and the sn at any epoch is within icecube s 2011/12 data acquisition season .
also , a complementary neutrino analysis reveals no long - term signal over the course of one year .
therefore , we consider the sn detection coincidental and the neutrinos uncorrelated to the sn . however , the sn is unusual and interesting by itself : it is luminous and energetic , bearing strong resemblance to the sn iin 2010jl , and shows signs of interaction of the sn ejecta with a dense circumstellar medium .
high - energy neutrino emission is expected in models of diffusive shock acceleration , but at a low , non - detectable level for this specific sn . in this paper
, we describe the sn ptf12csy and present both the neutrino and electromagnetic data , as well as their analysis . .
And you have already written the first three sentences of the full article: icecube is a cubic - kilometer - sized neutrino detector installed in the ice at the geographic south pole between depths of 1450 m and 2450 m @xcite .
it consists of an array of photon sensors , called digital optical modules ( doms ) , attached to 86 cables , called strings .
detector construction started in 2005 and finished in december 2010 ..
Please generate the next two sentences of the article | neutrino observation relies on the optical detection of cherenkov radiation emitted by secondary particles produced in neutrino interactions in ice or bedrock near icecube . due to the small neutrino interaction cross - section
, the kilometer - scale detector has an effective area of only for muon neutrinos of energy @xcite . as part of the optical follow - up ( ofu ) program , the icecube neutrino observatory records high - energy ( @xmath1 ) neutrino events at a rate of about @xmath2 , about 250 per day . |
6,791 | Suppose that you have an abstract for a scientific paper: most tidal dwarf galaxies ( tdgs ) so - far discussed in the literature may be considered as young ones or even newborns , as they are still physically linked to their parent galaxies by an umbilical cord : the tidal tail at the tip of which they are usually observed .
old tidal dwarf galaxies , completely detached from their progenitors , are still to be found . using n
body numerical simulations , we have shown that tidal objects as massive as @xmath0 solar masses may be formed in interacting systems and survive for more than one gyr .
old tdgs should hence exist in the universe .
they may be identified looking at a peculiarity of their genetic identity card " : a relatively high abundance in heavy elements , inherited from their parent galaxies . finally ,
using this technique , we revisit the dwarf galaxies in the local universe trying to find arguments pro and con a tidal origin .
# 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 presence of compact star - forming regions in the tidal tails of colliding galaxies is commonly observed .
the formation , in that environment , of super - star clusters with masses up to those of globular clusters has also often been reported ( e.g. , knierman et al . , 2003 ) . the existence of even more massive tidal objects , with global properties characteristics of dwarf galaxies , has been claimed for more than a decade ( see the review by duc & mirabel , 1999 ) . but whether such tidal dwarf galaxies " are genuine galaxies
i.e. they are gravitationally bound entities is still strongly debated ( see in this volume the contribution by hibbard & barnes and that of amram et al . and braine et al ..
Please generate the next two sentences of the article | for an alternative view ) .
but perhaps the more important issue of whether tdgs survive , escape from their parent galaxies , and significantly contribute to the overall population of dwarf galaxies , is a matter of speculation . |
6,792 | Suppose that you have an abstract for a scientific paper: high resolution optical ( hires / keck ) and uv ( stis / hst ) spectra , covering a large range of chemical transitions , are analyzed for three single cloud weak absorption systems along the line of sight toward the quasar pg @xmath0 .
weak absorption lines in quasar spectra trace metal
enriched environments that are rarely closely associated with the most luminous galaxies ( @xmath1 ) .
the two weak systems at @xmath2 and @xmath3 are constrained to have @xmath4 solar metallicity , while the metallicity of the @xmath5 system is not as well constrained , but is consistent with @xmath6th solar .
these weak clouds are likely to be local pockets of high metallicity in a lower metallicity environment .
all three systems have two phases of gas , a higher density region that produces narrower absorption lines for low ionization transitions , such as , and a lower density region that produces broader absorption lines for high ionization transitions , such as .
the profile for one system ( at @xmath2 ) can be fit with a single broad component ( @xmath7 ) , but those for the other two systems require one or two additional offset high ionization clouds . two possible physical pictures for the phase structure are discussed : one with a low ionization , denser phase embedded in a lower density surrounding medium , and the other with the denser clumps surrounding more highly ionized gas . .
And you have already written the first three sentences of the full article: weak absorbers , those with @xmath8 , constitute @xmath9% of the total absorber population @xcite at @xmath10
. they account for a fair fraction of the @xmath11 forest @xcite . unlike strong absorbers ( which almost always are associated with a @xmath1 galaxy @xcite )
, weak absorbers can usually not be associated with a @xmath1 galaxy within impact parameter @xmath12 kpc of the qso ( @xcite ; c. steidel , private communication ) ..
Please generate the next two sentences of the article | this lack of an association with bright galaxies suggests that weak absorbers may be a physically different population than strong absorbers .
studying the physical conditions of weak absorbers ( eg . , metallicity , ionization conditions , total column density , and size ) is useful for two reasons : 1 ) physical conditions provide clues as to the nature of these absorbers , whose physical origin is not known ; 2 ) weak clouds provide an opportunity to study metal |
6,793 | Suppose that you have an abstract for a scientific paper: the @xmath0beii @xmath1 3131 doublet has been observed in the solar - type stars 16 cyg a & b and in the late g - type star @xmath2 cnc , to derive their beryllium abundances .
16 cyg a & b show similar ( solar ) beryllium abundances while 16 cyg b , which has been proposed to have a planetary companion of @xmath3 @xmath4 , is known to be depleted in lithium by a factor larger than 6 with respect to 16 cyg a. differences in their rotational histories which could induce different rates of internal mixing of material , and the ingestion of a similar planet by 16 cyg a are discussed as potential explanations . the existence of two other solar - type stars which are candidates to harbour planetary - mass companions and which show lithium and beryllium abundances close to those of 16 cyg a , requires a more detailed inspection of the peculiarities of the 16 cyg system . for @xmath2 cnc , which is the coolest known object candidate to harbour a planetary - mass companion ( @xmath5 @xmath4 ) ,
we establish a precise upper limit for its beryllium abundance , showing a strong be depletion which constrains the available mixing mechanisms . observations of similar stars without companions are required to asses the potential effects of the planetary companion on the observed depletion .
it has been recently claimed that @xmath2 cnc appears to be a subgiant .
if this were the case , the observed strong li and be depletions could be explained by a dilution process taking place during its post - main sequence evolution . .
And you have already written the first three sentences of the full article: in very recent years , several stars have been proposed to have planetary companions on the basis of measured precise radial velocity variations .
this field of research is experiencing rapid development , and updated reviews of the present situation can be found in the proceedings of the workshop on _ brown dwarfs and extrasolar planets _ edited by rebolo et al .
( 1998 ) and in the extrasolar planets encyclopaedia by j. schneider ..
Please generate the next two sentences of the article | once a solar - type star has been suggested to harbour a planetary - mass companion , it is interesting to investigate any similarities with the sun , as well as to find possible differences with respect to other single stars .
chemical abundances are among the most important parameters to be compared and , in particular , precise abundances of light elements such as lithium and beryllium ( easy to destroy by @xmath6 nuclear reactions when the temperature reaches @xmath7 and @xmath8 k , respectively ) combined with the abundances of other elements which are not so readily destroyed in stellar interiors , should help to understand how the presence of planets may affect the chemical composition of their parent stars . |
6,794 | Suppose that you have an abstract for a scientific paper: a new approach is introduced to study qcd amplitudes at high energy and comparatively small momentum transfer .
novel cut diagrams , representing resummation of feynman diagrams , are used to simplify calculation and to avoid delicate cancellations encountered in the usual approach .
explicit calculation to the 6th order is carried out to demonstrate the advantage of cut diagrams over feynman diagrams .
= -1.5 cm = -1 cm epsf.tex * cut diagrams for high energy scatterings * + + .
And you have already written the first three sentences of the full article: the rapidity - gap events recently observed at hera @xcite revived the community s interest in regge - pole description of high energy scattering .
the word ` pomeron ' seldom heard in recent years is once again found in the lexicon of experimentalists .
it is perhaps then a good time to have a new look at the connection between perturbative qcd and regge pole ..
Please generate the next two sentences of the article | non - perturbative effect may be important for momentum transfer of the order of @xmath0 or smaller , but we shall avoid it by going to a larger momentum transfer if necessary .
it was proposed by low and nussinov @xcite some years ago that the pomeron may simply reflect a two - gluon exchange in qcd . |
6,795 | Suppose that you have an abstract for a scientific paper: this short paper reviews several recent key observations of the processes occurring in the lower atmosphere ( chromosphere and photosphere ) during flares .
these are : evidence for compact and fragmentary structure in the flare chromosphere , the conditions in optical flare footpoints , step - like variations in the magnetic field during the flare impulsive phase , and hot , dense ` chromospheric ' footpoints .
the implications of these observations for microwaves are also discussed . .
And you have already written the first three sentences of the full article: via imaging , spectroscopy and time - series analysis , the microwave part of the spectrum provides vital information on the properties of flare - accelerated particles and the plasma and the magnetic field in which their emission is formed .
although there are considerable complexities in modeling and interpreting the data , microwaves are uniquely rich in diagnostic information and are crucial for flare studies .
however , flares are characterised in part by the fact that - for the few minutes of the impulsive phase at least - emission is generated across the entire electromagnetic spectrum.
Please generate the next two sentences of the article | . therefore we have the ability to set our microwave observations in context , though in practice the number of flares with excellent multi - wavelength coverage including microwaves remains small .
this highlights the ongoing need for continued operation of facilities such as the nobeyama radioheliograph ( norh ) and radio polarimeters ( norp ) in the current era of multi - wavelength observations . in this short paper |
6,796 | Suppose that you have an abstract for a scientific paper: the calar alto observatory , located at 2168 m height above the sea level in continental europe , holds a significant number of astronomical telescopes and experiments , covering a large range of the electromagnetic domain , from gamma - ray to near - infrared .
it is a very well characterized site , with excellent logistics .
its main telescopes includes a large suite of instruments . at the present time ,
new instruments , namely cafe , panic and carmenes , are under development .
we are also planning a new operational scheme in order to optimize the observatory resources . .
And you have already written the first three sentences of the full article: the calar alto observatory is located at 2168 m height above the sea level , in the sierra de los filabres ( almeria - spain ) at 45 km from the mediterranean sea .
it is the second largest european astronomical site in the northern hemisphere just behind the observatorio del roque de los muchachos ( located in the island of la palma ) , and the most important in the continental europe ( with excellent communications , making logistics easy , unexpensive and reliable ) .
currently there are six telescopes located in the complex , three of them directly operated by the centro astronmico hispano alemn a.i.e ..
Please generate the next two sentences of the article | , a partnership between the spanish national research council ( csic ) and the german max - plank society ( mpg ) .
these telescopes include the zeiss 3.5 m , the largest telescope in the continental western europe . |
6,797 | Suppose that you have an abstract for a scientific paper: light - cone quantization always involves the solution of differential constraint equations .
the solutions to these equations include integration constants ( fields independent of @xmath0 ) .
these fields are unphysical but when they are consistently removed from the dynamics , additional operators ( induced operators ) , which would not be present if the integration constants were simply set to zero , are included in the dynamics .
these induced operators can be taken to act in the usual light - cone subspace , for instance , the space used for dlcq . here
, i shall give a derivation of two such operators .
the operators are derived starting from the qcd lagrangian but the derivation involves some guesses .
the operators will provide for the linear growth of the pion mass squared with the quark bare mass and for the splitting of the pi and the rho at zero quark mass . .
And you have already written the first three sentences of the full article: i shall discuss some work that i have done with simon dalley @xcite on induced operators in qcd .
i shall begin with a very brief review of the schwinger model , the one model that includes induced operators that can be analyzed in complete detail @xcite .
the reasons for reviewing the schwinger model are to remind ourselves that induced operators do exist and do have physical consequences , and to set some notation and ideas for the discussion of qcd , where the analysis can not be done in complete detail ..
Please generate the next two sentences of the article | i shall then derive two of the induced operators in qcd and illustrate aspects of their effects with simple models .
i shall end with a brief discussion . |
6,798 | Suppose that you have an abstract for a scientific paper: the effect of subcritical hadron bubbles on a first - order quark - hadron phase transition is studied .
these subcritical hadron bubbles are created due to thermal fluctuations , and can introduce a finite amount of phase mixing ( quark phase mixed with hadron phase ) even at and above the critical temperature . for reasonable choices of surface tension and correlation length , as obtained from the lattice qcd calculations , we show that the amount of phase mixing at the critical temperature remains below the percolation threshold .
thus , as the system cools below the critical temperature , the transition proceeds through the nucleation of critical - size hadron bubbles from a metastable quark - gluon phase ( qgp ) , within an inhomogeneous background populated by an equilibrium distribution of subcritical hadron bubbles .
the inhomogeneity of the medium results in a substantial reduction of the nucleation barrier for critical bubbles . using the corrected nucleation barrier
, we estimate the amount of supercooling for different parameters controlling the phase transition , and briefly discuss its implications to cosmology and heavy - ion collisions .
+ pacs number(s ) : 12.38.mh , 64.60.qb , 05.70.fh , 25.75-q , 98.80.cq .
And you have already written the first three sentences of the full article: the hadronization of quark gluon plasma ( qgp ) possibly produced in the early universe or expected to be formed in relativistic heavy - ion collisions has been the focus of much attention during the past few years .
however , the mechanism of hadronization ( qcd phase transition ) remains an open question .
the prediction of lattice qcd on the order of the transition is still unclear , if physical masses for quarks are used @xcite ..
Please generate the next two sentences of the article | quenched qcd ( no dynamical quarks ) shows a first - order phase transition , albeit a weak one , with small surface tension and latent heat @xcite . assuming the transition to be first - order , homogeneous nucleation theory @xcite has been invoked extensively to study the dynamics of the quark hadron phase transition both in the context of early universe as well as for the plasma produced during relativistic heavy - ion collisions @xcite . in this picture , the transition is initiated by the nucleation of critical - size hadron bubbles from a supercooled metastable qgp phase .
these hadron bubbles can grow against surface tension , converting the qgp phase into the hadron phase as the temperature drops below the critical temperature , @xmath0 . |
6,799 | Suppose that you have an abstract for a scientific paper: a three - dimensional orthoscheme is defined as a tetrahedron whose base is a right - angled triangle and an edge joining the apex and a non - right - angled vertex is perpendicular to the base .
a generalization , called complete orthoschemes , of orthoschemes is known in hyperbolic geometry .
roughly speaking , complete orthoschemes consist of three kinds of polyhedra ; either compact , ideal or truncated .
we consider a particular family of hyperbolic complete orthoschemes , which share the same base .
they are parametrized by the height " , which represents how far the apex is from the base .
we prove that the volume attains maximal when the apex is ultraideal in the sense of hyperbolic geometry , and that such a complete orthoscheme is unique in the family . .
And you have already written the first three sentences of the full article: in @xcite , kellerhals wrote
the most basic objects in polyhedral geometry are orthoschemes " , and she gave a formula to calculate the volumes of complete orthoschemes in the three - dimensional hyperbolic space .
what we discuss here is the existence and the uniqueness of the maximal volume of a family of complete orthoschemes parametrized by the height " . consider a family of pyramids in euclidean space with a fixed base polygon and the locus of apexes perpendicular to the base polygon ..
Please generate the next two sentences of the article | the volumes of pyramids strictly increases when the height increases , because pyramids strictly increases as a set . by the same reason , this phenomenon holds true for such a family of pyramids in hyperbolic space .
in contrast to the euclidean case , the volume approaches to a finite value . |
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