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8,400 | Suppose that you have an abstract for a scientific paper: we compare two types of tsallis distribution , i.e. , with and without thermodynamical description , using the experimental data from the star , phenix , alice and cms collaborations on the rapidity and energy dependence of the transverse momentum spectra in p+p collisions . both of them can give us the similar fitting power to the particle spectra .
we show that the tsallis distribution with thermodynamical description gives lower temperatures than the ones without it . the extra factor @xmath0 ( transverse mass ) in the tsallis distribution with thermodynamical description plays an important role in the discrepancies between the two types of tsallis distribution .
but for the heavy particles , the choice to use the @xmath0 or @xmath1 ( transverse energy ) in the tsallis distribution becomes more crucial .
# 1#2#3#4#1 , # 2 , # 3 , # 4 . .
And you have already written the first three sentences of the full article: the particle spectrum is a basic quantity directly measured in the experiments and it can reveal the information of particle production mechanism in heavy - ion collisions .
many physicists have devoted themselves to studying the particle spectra produced in the heavy - ion collisions using thermodynamical approaches , phenomenological methods , transport models _
recently , the tsallis distribution , which was first proposed about twenty - seven years ago as a generalization of the boltzmann - gibbs distribution @xcite , has attracted many theorists and experimentalists attention in high energy heavy - ion collisions @xcite ..
Please generate the next two sentences of the article | the excellent ability to fit the spectra of identified hadrons and charged particles in a large range of @xmath2 up to 200 gev , which covers 15 orders of magnitude , is quite impressive .
this spectacular result was first shown by wong _ |
8,401 | Suppose that you have an abstract for a scientific paper: we present numerical simulations of penetrative convection and gravity wave excitation in the sun .
gravity waves are self - consistently generated by a convective zone overlying a radiative interior .
we produce power spectra for gravity waves in the radiative region as well as estimates for the energy flux of gravity waves below the convection zone .
we calculate a peak energy flux in waves below the convection zone to be three orders of magnitude smaller than previous estimates for m=1 .
the simulations show that the linear dispersion relation is a good approximation only deep below the convective - radiative boundary .
both low frequency propagating gravity waves as well as higher frequency standing modes are generated ; although we find that convection does not continually drive the standing g - mode frequencies .
[ firstpage ] sun : mixing , internal gravity waves , convection .
And you have already written the first three sentences of the full article: convection bounded by a stable region is important in all aspects of stellar evolution .
the depth to which convective motions can overshoot into an adjacent stable layer has important consequences for many stages of stellar evolution , from dredge up in late stages of stellar evolution @xcite to nucleosynthesis in classical novae @xcite . in the sun
, the overshoot region at least partially overlaps the tachocline ( the shear layer at the base of the convection zone where the rotation changes from being differential in the convection zone to solid body in the radiation zone and the likely site of toroidal field generation in the dynamo process ) ..
Please generate the next two sentences of the article | therefore , understanding the extent of the overshoot is necessary for understanding the nature of the tachocline ; is it a violent region , constantly bombarded by overshooting plumes , or is it a laminar region just below the overshoot ?
the answer to this question can constrain models for the solid body rotation of the solar interior . |
8,402 | Suppose that you have an abstract for a scientific paper: in this paper we consider the modified craig sneyd ( mcs ) scheme which forms a prominent time stepping method of the alternating direction implicit type for multidimensional time - dependent convection - diffusion equations with mixed spatial derivative terms .
when the initial function is nonsmooth , which is often the case for example in financial mathematics , application of the mcs scheme can lead to spurious erratic behaviour of the numerical approximations .
we prove that this undesirable feature can be resolved by replacing the very first mcs timesteps by several ( sub)steps of the implicit euler scheme .
this technique is often called rannacher time stepping .
we derive a useful convergence bound for the mcs scheme combined with rannacher time stepping when it is applied to a model two - dimensional convection - diffusion equation with mixed - derivative term and with dirac - delta initial data .
ample numerical experiments are provided that show the sharpness of our obtained error bound .
* key words : * convection - diffusion equations , adi splitting schemes , convergence analysis , rannacher time stepping . .
And you have already written the first three sentences of the full article: in financial mathematics , the fair value @xmath0 of a european style option on two underlying assets is modelled by the two - dimensional _ black scholes partial differential equation _ ( pde ) , see e.g. @xcite , @xmath1 for @xmath2 . here
, @xmath3 denotes the time to maturity @xmath4 and we assume real parameters @xmath5 .
the pde is provided with an initial condition that is defined through the payoff of the option ..
Please generate the next two sentences of the article | the mixed spatial derivative term in represents the correlation between both asset prices in the two - dimensional black scholes model .
mixed spatial derivative terms are very important , notably , in the field of financial option valuation theory . here |
8,403 | Suppose that you have an abstract for a scientific paper: the omegacam wide - field imager will start operations at the eso vlt survey telescope at paranal , chile , in 2007 .
the photometric calibration of omegacam data depends on standard star measurements that cover the complete 1 square degree fov of omegeacam .
a catalog fullfilling this requirement for eight landolt equatorial fields , denoted the omegacam secondary standards catalog , will be constructed from omegacam observations during the first year of operations . here
we present the preliminary catalog which will be used to bootstrap the construction of the omegacam secondary standards catalog .
thus the preliminary catalog will be used to assess the performance of omegacam+vst early - on .
the catalog is based on wfc data from the int at la palma . .
And you have already written the first three sentences of the full article: the number of wide field optical imagers with a large fov ( @xmath0 square degree ) available at astronomical telescopes is growing .
these instruments perform surveys which can cover thousands of square degrees of sky aimed at a wide range of galactic and extragalactic science goals .
the surveys are made public often promptly allowing astronomers from around the globe to use the data for their own specific scientific needs ..
Please generate the next two sentences of the article | the imagers contain many ccds and often elaborate components to correct for optical distorsions over the fov .
accurate and robust photometric calibration over the complete area of such surveys is required to successfullly use the data for the many different ( and sometimes unforeseen ) science projects . in this article |
8,404 | Suppose that you have an abstract for a scientific paper: we study diffusion of information packets on several classes of structured networks .
packets diffuse from a randomly chosen node to a specified destination in the network . as local transport rules we consider random diffusion and an improved local search method .
numerical simulations are performed in the regime of stationary workloads away from the jamming transition .
we find that graph topology determines the properties of diffusion in a universal way , which is reflected by power - laws in the transit - time and velocity distributions of packets . with the use of multifractal scaling analysis and arguments of non - extensive statistics
we find that these power - laws are compatible with super - diffusive traffic for random diffusion and for improved local search .
we are able to quantify the role of network topology on overall transport efficiency .
further , we demonstrate the implications of improved transport rules and discuss the importance of matching ( global ) topology with ( local ) transport rules for the optimal function of networks . the presented model should be applicable to a wide range of phenomena ranging from internet traffic to protein transport along the cytoskeleton in biological cells .
pacs : 89.75.fb , 89.20.hh , 05.65.+b , 87.23.ge .
And you have already written the first three sentences of the full article: properties of different types of networks have begun to attract the interest of statistical physicists .
the spectrum of network related problems include , among many others , ordinary traffic in a city @xcite , distribution of nutrients in the vascular system @xcite , distribution of goods and wealth in economies , queuing problems on information networks @xcite , biochemical- and gene expression pathways @xcite .
it has been recognized that most natural and man - made networks evolve in time and that their structure emerged as result of microscopic evolution rules @xcite . in many networks a scale - free linking structure.
Please generate the next two sentences of the article | was found @xcite which emerges from complex processes of self - organization with specific constraints .
maybe the most prominent example of such a scale - free network is the world - wide web @xcite and the internet @xcite . |
8,405 | Suppose that you have an abstract for a scientific paper: results are presented for the entanglement entropy and spectrum of half - filled graphene following the switch on of a circularly polarized laser .
the laser parameters are chosen to correspond to several different floquet chern insulator phases .
the entanglement properties of the unitarily evolved wavefunctions are compared with the state where one of the floquet bands is completely occupied .
the true states show a volume law for the entanglement , whereas the floquet states show an area law .
qualitative differences are found in the entanglement properties of the off - resonant and on - resonant laser .
edge states are found in the entanglement spectrum corresponding to certain physical edge states expected in a chern insulator .
however , some edge states that would be expected from the floquet band structure are missing from the entanglement spectrum .
an analytic theory is developed for the long time structure of the entanglement spectrum .
it is argued that only edge states corresponding to off - resonant processes appear in the entanglement spectrum . .
And you have already written the first three sentences of the full article: floquet topological insulators , a new kind of topological phase , have been attracting much attention in recent years @xcite .
these phases are produced by periodically time - dependent hamiltonians . by tuning the amplitude , phase , and frequency of the periodic drive myriad topological phases
may be realized . among floquet topological insulators ,.
Please generate the next two sentences of the article | effective time - reversal breaking floquet chern insulators ( fcis ) have even been experimentally realized in cold - atoms @xcite and optical wave - guides @xcite .
these states contain unique @xmath0 edge states that have no equivalent in a static system @xcite . |
8,406 | Suppose that you have an abstract for a scientific paper: brown dwarf spectra are rich in information revealing of the chemical and physical processes operating in their atmospheres .
we apply a recently developed atmospheric retrieval tool to an ensemble of late t - dwarf ( 600 - 800k ) near infrared spectra . with these spectra
we are able to place direct constraints the molecular abundances of h@xmath0o , ch@xmath1 , co , co@xmath0 , nh@xmath2 , h@xmath0s , and na+k , gravity , thermal structure ( and effective temperature ) , photometric radius , and cloud optical depths .
we find that ammonia , water , methane , and the alkali metals are present and well constrained in all 11 objects . from the abundance constraints we find no significant trend in the water , methane , or ammonia abundances with temperature , but find a very strong ( @xmath325@xmath4 ) increasing trend in the alkali metal abundances with effective temperature , indicative of alkali rainout .
we also find little evidence for optically thick clouds . with the methane and water abundances ,
we derive the intrinsic atmospheric metallicity and carbon - to - oxygen ratios .
we find in our sample , that metallicities are typically sub solar and carbon - to - oxygen ratios are somewhat super solar , different than expectations from the local stellar population .
we also find that the retrieved vertical thermal profiles are consistent with radiative equilibrium over the photospheric regions .
finally , we find that our retrieved effective temperatures are lower than previous inferences for some objects and that our radii are larger than expectations from evolutionary models , possibly indicative of un - resolved binaries .
this investigation and methodology represents a paradigm in linking spectra to the determination of the fundamental chemical and physical processes governing cool brown dwarf atmospheres . .
And you have already written the first three sentences of the full article: brown dwarf spectra contain a wealth of information about the physical and chemical processes occurring in their atmospheres .
such processes include , but are not limited to : vertical atmospheric energy balance , disequilibrium chemistry , cloud formation / distribution and subsequent impact on molecular composition , and links to formation and evolution ( see marley & robinson 2015 review ) .
the main diagnostic quantities that provide insight into these processes , that can be obtained directly from a spectrum are : vertical thermal structure , molecular abundances , spectroscopic radius , and cloud properties ..
Please generate the next two sentences of the article | deriving these diagnostic quantities is no simple task .
progress in characterization always involves the interplay between observational and modeling efforts . |
8,407 | Suppose that you have an abstract for a scientific paper: the presence of heavy elements in the atmospheres of the hottest h - rich da white dwarfs has been the subject of considerable interest .
while theoretical calculations can demonstrate that radiative forces , counteracting the effects of gravitational settling , can explain the detections of individual species , the predicted abundances do not accord well with observation .
however , accurate abundance measurements can only be based on a thorough understanding of the physical structure of the white dwarf photospheres , which has proved elusive .
recently , the availability of new non - lte model atmospheres with improved atomic data has allowed self - consistent analysis of the euv , far uv and optical spectra of the prototypical object g191@xmath0b2b .
even so , the predicted and observed stellar fluxes remain in serious disagreement at the shortest wavelengths ( below @xmath1 ) , while the inferred abundances remain largely unaltered .
we show here that the complete spectrum of g191@xmath0b2b can be explained by a model atmosphere where fe is stratified , with increasing abundance at greater depth .
this abundance profile may explain the difficulties in matching observed photospheric abundances , usually obtained by analyses using homogeneous model atmospheres , to the detailed radiative levitation predictions . particularly as the latter are only strictly valid for regions deeper than where the euv / far uv lines and continua are formed .
furthermore , the relative depletion of fe in the outer layers of the atmosphere may be evidence for radiatively driven mass loss in g191@xmath0b2b .
[ firstpage ] stars : abundances stars : atmospheres stars : white dwarfs ultraviolet : stars x - rays : stars . .
And you have already written the first three sentences of the full article: following the first discovery of the presence of heavy elements in the photospheres of h - rich ( da ) white dwarfs with _ iue _
( bruhweiler & kondo 1981 , 1983 ) , it is now well established that they are ubiquitous in the group of hottest objects , with effective temperatures in excess of 55000k ( e.g. marsh _
et al . _.
Please generate the next two sentences of the article | 1997b ; barstow _ et al . _
extensive further studies in the far uv have eventually revealed the presence of absorption lines from c , n , o , si , s , p , fe and ni in a number of objects ( e.g. vennes _ |
8,408 | Suppose that you have an abstract for a scientific paper: we analyze the type ii plateau supernovae ( sn ii - p ) 2005cs and 2006bp with the non - lte model atmosphere code cmfgen .
we fit 13 spectra in the first month for sn 2005cs and 18 for sn 2006bp .
_ swift _ ultraviolet photometry and ground - based optical photometry calibrate each spectrum .
our analysis shows both objects were discovered less than 3 days after they exploded , making these the earliest sn ii - p spectra ever studied .
they reveal broad and very weak lines from highly - ionized fast ejecta with an extremely steep density profile .
we identify heii4686 emission in the sn 2006bp ejecta .
days later , the spectra resemble the prototypical type ii - p sn 1999em , which had a supergiant - like photospheric composition . despite the association of sn 2005cs with possible x - ray emission ,
the emergent uv and optical light comes from the photosphere , not from circumstellar emission .
we surmise that the very steep density fall - off we infer at early times may be a fossil of the combined actions of the shock wave passage and radiation driving at shock breakout .
based on tailored cmfgen models , the direct - fitting technique and the expanding photosphere method both yield distances and explosion times that agree within a few percent .
we derive a distance to ngc 5194 , the host of sn 2005cs , of [email protected] and [email protected] for sn 2006bp in ngc 3953 .
the luminosity of sn 2006bp is 1.5 times that of sn 1999em , and 6 times that of sn 2005cs .
reliable distances to type ii - p supernovae that do not depend on a small range in luminosity provide an independent route to the hubble constant and improved constraints on other cosmological parameters . .
And you have already written the first three sentences of the full article: although radiation represents a negligible fraction of the energy in core - collapse supernova ( sn ) explosions , most of what we know about these events is inferred from the analysis of spectra and light curves .
the gravitational binding - energy of the newly - formed protoneutron star is on the order of 10@xmath1erg . within milliseconds after
core bounce , a few @xmath2 10@xmath3erg of this energy is used to photodissociate the infalling outer iron core . starting with an electron - neutrino burst when the core reaches nuclear densities , the radiation of neutrinos of all flavors operates over a few tens of seconds after the bounce as the protoneutron star cools , and carries away a few @xmath2 10@xmath3erg ..
Please generate the next two sentences of the article | these neutrinos are believed to deposit @xmath410@xmath5erg ( 1% of the total ) into the infalling progenitor mantle , reversing the accretion , and to provide the internal and kinetic energy for the sn ejecta ( woosley & janka 2005 ) . only @xmath410@xmath6erg ( 0.01% of the total ) is eventually processed into light , that gets radiated with a rate equivalent to a few @xmath2 10@xmath7 sustained for three months .
depending on the progenitor radius , the shock emerges at the surface between a few hours and a day after core bounce , with a radiative precursor that is expected to heat and accelerate the surface layers , producing a soft x - ray flash ( chevalier 1982 ; ensman & burrows 1992 ; matzner & mckee 1999 ; blinnikov et al . |
8,409 | Suppose that you have an abstract for a scientific paper: in @xcite problem d22 richard guy asked for the existence of simplices with integer lengths , areas , volumes . in dimension two this is well known , these triangles are called _
heron triangles_. here i will present my results on heron tetrahedra , their connection to the existence of an integer box ( problem d18 ) , the tools for the search for higher dimensional heron simplices and my nice embedding conjecture about heron simplices , which i can only proof in dimension two , but i verified it for a large range in dimension three . .
And you have already written the first three sentences of the full article: ( heron formula ) let @xmath0 , @xmath1 and @xmath2 be the lengths of the sides of a triangle , @xmath3 the half of the perimeter and @xmath4 the area . then holds @xmath5 @xmath6 now we define : a _ heron triangle _ is a triangle with integer sides and area .
[ prop : peri ] the perimeter of a heron triangle is even .
assume the perimeter is odd ..
Please generate the next two sentences of the article | then all factors on the right hand side of equation ( [ eq : heron ] ) are halves of odd integers , so the product is an odd integer divided by @xmath7 , which can not be an integer .
@xmath6 if the sides of a heron triangle have a common factor @xmath8 , then the area is divisible by @xmath9 , |
8,410 | Suppose that you have an abstract for a scientific paper: time - reversal and inversion breaking in the pseudogap region of the cuprate compounds have been proposed and detected by means of arpes in the compound bi-2212 . given the implication of the effect in the physics of the cuprate superconductors , it is important to check the conclusions through quite independent experimental techniques . we show how time - reversal and inversion breaking may be revealed in the cuprates through resonant x - ray scattering and through non - reciprocal or magnetochiral dichroism . 2 .
And you have already written the first three sentences of the full article: time - reversal breaking phases are predicted to occur in the so called _ pseudogap _ region of the phase diagram of the cuprates.@xcite these phases do not change the translational symmetry of the lattice and therefore do not produce new bragg spots in ordinary diffraction experiments . since the spontaneous magnetic field generated averages to zero in each unit cell , no simple magnetic dichroism effects arise .
however , it was shown that time - reversal breaking phases produce angle dependent dichroism in photoemission with circularly polarized photons.@xcite one such experiment has indeed detected such a phase.@xcite in this phase both time - reversal symmetry and inversion are broken but their product is preserved .
( such a symmetry is called _.
Please generate the next two sentences of the article | magnetoelectric_.@xcite ) if this experiment is correct , the principal features of the theory of cuprates may be said to have been found .
it is therefore important to have independent experiments of quite a different kind verifying the existence of such phases . |
8,411 | Suppose that you have an abstract for a scientific paper: how to distinguish and quantify deterministic and random influences on the statistics of turbulence data in meteorology cases is discussed from first principles .
liquid water path ( lwp ) changes in clouds , as retrieved from radio signals , upon different delay times , can be regarded as a stochastic markov process .
a detrended fluctuation analysis method indicates the existence of long range time correlations .
the fokker - planck equation which models very precisely the lwp @xmath0 empirical probability distributions , in particular , their non - gaussian heavy tails is explicitly derived and written in terms of a drift and a diffusion coefficient .
furthermore , kramers - moyal coefficients , as estimated from the empirical data , are found to be in good agreement with their first principle derivation .
finally , the equivalent langevin equation is written for the lwp increments themselves .
thus rather than the existence of hierarchical structures , like an energy cascade process , _ strong correlations _ on different @xmath1 @xmath2 , from small to large ones , are considered to be proven as intrinsic ingredients of such cloud evolutions . 0.5 cm _ pacs numbers : _
05.45.tp , 05.45.gg , 93.30.fd , 89.69.+x ; 02.50.le , 05.40.-a , 47.27.ak , 87.23.ge 0.5 cm .
And you have already written the first three sentences of the full article: in order to establish a sound understanding for any scientific phenomenon , one has from numerical data to obtain laws which can be next derived theoretically .
some difficulty arises in particular in nonlinear dynamical systems because of the problem to sort out noise from both chaos and deterministic components [ bhattacharya and kanjilal , 2000 ; provenzale et al . ,
moreover , algorithms for solving the inverse problem for nonlinear systems with underlying unknown dynamical processes are notoriously hardly reliable [ theiler , 1992 ] ..
Please generate the next two sentences of the article | in fact , to extract dynamical equations for chaotic - like data is an enormous challenge [ rowlands , 1992 ] . practically one is often led to empirical relationships .
this is the case of the meteorology field where there is a widely mixed set of various ( sometimes ) unknown influences , over different time and space scales . |
8,412 | Suppose that you have an abstract for a scientific paper: we discuss importance sampling schemes for the estimation of finite time exit probabilities of small noise diffusions that involve escape from an equilibrium . a factor that complicates
the analysis is that rest points are included in the domain of interest .
we build importance sampling schemes with provably good performance both pre - asymptotically , i.e. , for fixed size of the noise , and asymptotically , i.e. , as the size of the noise goes to zero , and that do not degrade as the time horizon gets large .
simulation studies demonstrate the theoretical results . .
And you have already written the first three sentences of the full article: this paper considers the use of importance sampling for estimating hitting or exit probabilities for stochastic processes .
the process model is a @xmath0-dimensional diffusion @xmath1 satisfying the stochastic differential equation ( sde ) @xmath2 where @xmath3 and @xmath4 is a standard @xmath0-dimensional wiener process .
of particular interest is the case of gradient flows , @xmath5 , and constant diffusion coefficient , though many aspects of the analysis are more generally applicable ..
Please generate the next two sentences of the article | let @xmath6 be an open set and denote by @xmath7 the exit time of @xmath8 from @xmath9 .
we are concerned with the estimation of quantities such as the probability that @xmath10 leaves @xmath9 before some time @xmath11 , or that it exits through a particular subset @xmath12 before @xmath13 , and related expected values . |
8,413 | Suppose that you have an abstract for a scientific paper: we perform density functional theory plus dynamical mean field theory calculations to investigate internal charge transfer in an artificial superlattice composed of alternating layers of vanadate and manganite perovskite and ruddlesden - popper structure materials .
we show that the electronegativity difference between vanadium and manganese causes moderate charge transfer from vo@xmath0 to mno@xmath0 layers in both perovskite and ruddlesden - popper based superlattices , leading to hole doping of the vo@xmath0 layer and electron doping of the mno@xmath0 layer .
comparison of the perovskite and ruddlesden - popper based heterostructures provides insights into the role of the apical oxygen .
our first principles simulations demonstrate that the combination of internal charge transfer and quantum confinement provided by heterostructuring is a powerful approach to engineering electronic structure and tailoring correlation effects in transition metal oxides . .
And you have already written the first three sentences of the full article: advances in thin film epitaxy growth techniques have made it possible to induce emergent electronic @xcite , magnetic @xcite and orbital @xcite states , which are not naturally occurring in bulk constituents , at atomically sharp transition metal oxide interfaces @xcite .
for example , the interface between the two nonmagnetic band insulators laalo@xmath1 and srtio@xmath1 @xcite has been reported to exhibit both conductance @xcite and magnetism @xcite ( see reviews @xcite and references therein ) . at the interface of mott insulators srmno@xmath1 and lamno@xmath1 , hole doping on the mn sites leads to rich phenomena , including metal - insulator transition , charge / spin / orbital ordering and magnetoresistance @xcite . in laalo@xmath1/srtio@xmath1 and related heterostructures , the interface electron gas is believed to be produced by the polar catastrophe mechanism , which leads to the transfer of charge from the sample surface to the interface . here , we consider a different mechanism for controlling the electronic properties of an interface : namely , electronegativity - driven charge transfer .
recently , we have shown that internal charge transfer in a latio@xmath1/lanio@xmath1 superlattice transforms metallic lanio@xmath1 into a @xmath2 mott insulator and mott insulating latio@xmath1 into a @xmath3 band insulator @xcite ..
Please generate the next two sentences of the article | a natural question arises : can we reverse the process and utilize internal charge transfer to induce conductance via oxide interfaces ? in this regard , it is very tempting to explore mott interfaces ( one or both constituents are mott insulators ) due to the unusual phenomena ( colossal magnetoresistance and high temperature superconductivity ) exhibited in certain doped mott insulators .
in this paper we use density functional theory + dynamical mean field theory ( dft+dmft ) to theoretically design a superlattice with emergent metallic behavior . |
8,414 | Suppose that you have an abstract for a scientific paper: a comprehensive study of the electronic properties of monoclinic @xmath0 from both an experimental and a theoretical point of view is presented .
we focus on the investigation of the fermi body and the band structure using angle resolved photoemission spectroscopy , de haas - van alphen measurements , and electronic structure calculations . for the latter , the new full - potential augmented spherical wave ( asw ) method has been applied .
very good agreement between the experimental and theoretical results is found . in particular , all fermi surface sheets are correctly identified by all three approaches .
previous controversies concerning additional hole - like surfaces centered around the z- and b - point could be resolved ; these surfaces were an artefact of the atomic - sphere approximation used in the old calculations .
our results underline the importance of electronic structure calculations for the understanding of @xmath0 and the neighbouring rutile - type early transition - metal dioxides .
this includes the low - temperature insulating phases of @xmath1 and @xmath2 , which have crystal structures very similar to that of molybdenum dioxide and display the well - known prominent metal - insulator transitions . .
And you have already written the first three sentences of the full article: the metal - insulator transitions of the early transition - metal oxides have been attracting a lot of attention for decades . in particular , since the first report by morin , @xcite much interest has centered about the cornerstone materials @xmath3 and @xmath1 .
this is mainly due to the fact , that these compounds display first order phase transitions with very narrow hystereses of only few kelvin and strong changes of the conductivity of several orders of magnitude , making them promising candidates for applications .
interestingly , the transitions of both compounds are accompanied by characteristic structural changes , which initiated a discussion about the driving forces . dispute centered about the question whether the transitions are driven predominantly by structural instabilities of the parent corundum and rutile structure , respectively , or else by strong electronic correlations . nowadays , the importance of the latter is widely accepted ..
Please generate the next two sentences of the article | however , despite intense work , the questions concerning the origins of the respective transitions have not yet been satisfactorily answered . in @xmath1 ,
the metal - insulator transition occurs at 340k and is connected with a structural change from the rutile structure to a distorted monoclinic structure . |
8,415 | Suppose that you have an abstract for a scientific paper: theoretical model is presented to describe the anomalous ordered phase of pr ions in prba@xmath0cu@xmath1o@xmath2 below @xmath3k .
the model considers the pr multipole degrees of freedom and coupling between the cu and pr subsystems .
we identify the symmetry allowed coupling of cu and pr ions and conclude that only an @xmath4-plane pr dipole ordering can explain the cu spin rotation observed at @xmath5 by neutron diffraction by boothroyd _
et al . _
[ a. t. boothroyd _
et al . _ ,
phys .
rev .
lett . * 78 * , 130 ( 1997 ) ] . a substantial enhancement of the pr ordering temperature is shown to arise from the cu - pr coupling which is the key for the anomalous magnetic behavior in prba@xmath0cu@xmath1o@xmath2 . .
And you have already written the first three sentences of the full article: non - superconducting prba@xmath0cu@xmath1o@xmath2 compound attracted considerable attention in the last two decades because of its intriguing magnetic and electronic properties within the reba@xmath6cu@xmath7o@xmath2 family of compounds ( re = rare earth atom).@xcite in spite of the great efforts from both experimental and theoretical sides , numerous problems remain unresolved such as the suppression of superconductivity and the nature of the long - range ordered state of pr sublattice with a unique , about an order of magnitude larger than for other rare earth atoms , ordering temperature .
although , there exists a discussion whether the ground state of prba@xmath0cu@xmath1o@xmath2 is really a non - superconducting , insulating material with a magnetically ordered cu and pr sublattices , herein we consider this modification of prba@xmath0cu@xmath1o@xmath2 as `` canonical '' and treat it solely herein .
we note that superconductivity in prba@xmath0cu@xmath1o@xmath2 was reported@xcite and a non - magnetic pr ground state was found by @xmath8pr nmr.@xcite it was suggested that these observations may result from a non - stoichiometric compound , i.e. when pr occupies only about a half of the rare - earth sites , and the other half is occupied by the non - magnetic ba.@xcite the theoretical model of fehrenbacher and rice , i.e. the hybridization of pr @xmath9 and the nearest neighbor o @xmath10 orbitals is the most accepted model to account for the absence of superconductivity in prba@xmath0cu@xmath1o@xmath2 ..
Please generate the next two sentences of the article | it is suggested that the localization of holes in the hybridized @xmath9-@xmath10 orbitals renders the material non - superconducting.@xcite although the non - superconducting nature of prba@xmath0cu@xmath1o@xmath11 compound is a challenging and interesting problem , we concentrate herein exclusively on the low - temperature pr ordering .
prba@xmath0cu@xmath1o@xmath2 is an insulator for every @xmath12 and the cu spins in the cuo@xmath0 planes order antiferromagnetically at temperatures of @xmath13k and @xmath14k for @xmath15 and @xmath16 , respectively.@xcite as the temperature is further decreased , the pr sublattice also undergoes a phase transition@xcite in the temperature range @xmath17k depending on @xmath12 , which appears as an anomaly in the temperature dependence of thermodynamic quantities.@xcite mssbauer spectroscopy,@xcite neutron diffraction,@xcite and nmr@xcite showed that the pr magnetic moments order antiferromagnetically below @xmath18 . however , there is no consensus among these experiments with respect to the magnitude of the ordered pr moment , its direction , and the nature of this transition . |
8,416 | Suppose that you have an abstract for a scientific paper: the anisotropic paramagnetism and specific heat in nd@xmath0ti@xmath0o@xmath1 single crystals are investigated .
angular dependence of the magnetization and weiss temperatures show the dominant role of the crystal field effect in the magnetization . by incorporating the results from the diluted samples , contributions to weiss temperature from exchange interactions and crystal field interactions
are isolated .
the exchange interactions are found to be ferromagnetic , while the crystal field contributes a large negative part to the weiss temperature , along all three crystallographic directions .
the specific heat under magnetic field reveals a two - level schottky ground state scheme , due to the zeeman splitting of the ground state doublet , and the @xmath2-factors are thus determined .
these observations provide solid foundations for further investigations of nd@xmath0ti@xmath0o@xmath1 . .
And you have already written the first three sentences of the full article: rare earth titanates ( r@xmath0ti@xmath0o@xmath1 ) are an interesting family of materials showing rich ferroelectric @xcite and magnetic properties @xcite .
the common crystal structures @xcite for these materials are cubic pyrochlore for small rare earth ions ( sm@xmath3 lu@xmath3 ) and monoclinic for large rare earth ions ( la@xmath3 nd@xmath3 ) . the magnetic properties of the former have been explored extensively during the recent years @xcite . the subtle interplay among the various interactions including crystal field , exchange and dipole - dipole , coupled with geometrical frustration specific to the pyrochlore lattice @xcite , has led to exotic magnetic phases such as spin ice @xcite and spin liquid @xcite .
these phases are extremely sensitive to doping and external stimuli such as pressure @xcite and magnetic fields @xcite ..
Please generate the next two sentences of the article | interesting dynamic processes have also been identified @xcite . on the other hand ,
the rare earth titanates with a monoclinic structure have received much less attention . due to the removal of geometric frustration , |
8,417 | Suppose that you have an abstract for a scientific paper: we investigate the dynamical evolution of clusters of galaxies and their observational consequences during off - center mergers , explicitly considering the relaxation process between ions and electrons in intracluster medium by n - body and hydrodynamical simulations . in the contracting phase
a bow shock is formed between the two subclusters .
the observed temperature between two peaks in this phase depends on the viewing angle even if the geometry of the system seems to be very simple like head - on collisions . around the most contracting epoch , when we observe merging clusters nearly along the collision axis , they look like spherical relaxed clusters with large temperature gradients . in the expanding phase , spiral bow shocks occur . as in head - on mergers ,
the electron temperature is significantly lower than the plasma mean one especially in the post - shock regions in the expanding phase .
when the systems have relatively large angular momentum , double - peak structures in the x - ray images can survive even after the most contracting epoch .
morphological features in both x - ray images and electron temperature distribution characteristic to off - center mergers are seriously affected by the viewing angle . when the clusters are observed nearly along the collision axis ,
the distribution of galaxies line - of - sight ( los ) velocities is a good indicator of mergers . in the contracting phase , an negative kurtosis and a large skewness
are expected for nearly equal mass collisions and rather different mass ones , respectively . to obtain statistically significant results , about @xmath0 galaxies
los velocities are required . for
nearby clusters ( @xmath1 ) , large redshift surveys such as 2df will enable us to study merger dynamics . .
And you have already written the first three sentences of the full article: according to the hierarchical clustering scenario such as the cold dark matter cosmology , it is believed that clusters of galaxies ( cgs ) are formed through subcluster merger and/or absorption of smaller groups .
mergers of cgs are the most energetic events in the universe after the big bang , where the total kinetic energy of the two subclusters reaches @xmath2 ergs .
thus , it is most likely that they affect various properties of cgs . in intracluster medium ( icm ) , mergers make strong bulk - flow motion and shocks . these cause characteristic morphology of x - ray images ( elongation and/or substructures ) and complex electron temperature structures in icm ( e.g. , honda et al ..
Please generate the next two sentences of the article | 1996 ; churazov et al .
1998 ; donnelly et al . |
8,418 | Suppose that you have an abstract for a scientific paper: we use simulations of heavy quark effective field theory to calculate the isgur - wise function , and we demonstrate the feasibility of calculating the matrix element for the @xmath0 decay in the lattice heavy quark effective theory ( hqet ) . .
And you have already written the first three sentences of the full article: we describe the calculation of the hadronic matrix elements that are required for the extraction of the @xmath1 and @xmath2 ckm matrix elements from experimental data @xcite . to reach the bottom quark mass our strategy is to interpolate between results from relativistic quarks with @xmath3 and results from lattice hqet @xcite .
here we discuss only the hqet simulations , as our clover form factor simulations have only just started .
all of our simulations use @xmath4 dynamical staggered configurations with a volume @xmath5 and @xmath6 ..
Please generate the next two sentences of the article | the isgur - wise function is the qcd matrix element required in the extraction of @xmath1 from experimental data .
experimental measurements of the slope of the isgur - wise function vary from @xmath7 to @xmath8 , and the variations in theoretical predictions are nearly as large @xcite . initial attempts to calculate the isgur - wise function in lattice hqet had problems either with the signal to noise ratio @xcite or the renormalization factors @xcite . |
8,419 | Suppose that you have an abstract for a scientific paper: rare astrophysical events cosmological gamma - ray bursts with energies over gev are considered as an origin of information about some susy parameters .
the model of generation of the powerful gamma - ray bursts is proposed . according to this model the gamma - ray burst represents as a result of the collapse and the total annihilation of the neutralino clump .
about 80 % of the clump mass radiates during @xmath0 second at the final stage of annihilation . the annihilation spectrum and its characteristic energies are calculated in the framework of split higgsino model . .
And you have already written the first three sentences of the full article: since the direct experimental information about structure of susy model and values of susy particles masses are absent now we try to extract any possible data from the cosmology . from the recent wmap data @xcite the mass density in the universe is equal to its critical value @xmath1 ; the structured dark matter ( dm ) and
the isotropic and homogeneous dark energy ( de ) contribute to this density @xmath2 and @xmath3 , correspondingly . as it is known , baryons give @xmath4 of the total universe s mass . in our galaxy @xmath5 of total mass
is the mass of dm which forms the halo ..
Please generate the next two sentences of the article | the lightest supersymmetric particles ( lsp ) neutralino are supposed to be the main contributors to the cold ( and hot ) dm .
the physics of lsp is discussed intensively in various aspects @xcite . to observe the neutralino appearance in space or land experiments one can use of the different ways . |
8,420 | Suppose that you have an abstract for a scientific paper: liquid crystal elastomers are rubbers with liquid crystal order .
they contract along their nematic director when heated or illuminated .
the shape changes are large and occur in a relatively narrow temperature interval , or at low illumination , around the nematic isotropic transition .
we present a conceptual design of a mechanical , turbine - based engine using photo - active liquid crystal elastomers to extract mechanical work from light .
its efficiency is estimated to be 40% . .
And you have already written the first three sentences of the full article: we propose a mechanical turbine - based engine to harness the contractions of soft , photo - responsive solids with a large stroke .
we thus take photo - active nematic liquid crystal elastomers ( lces ) as our working material .
related engines have been proposed before , for instance based on the bend response of strips of nematic photo - glasses connecting two wheels @xcite . in contrast , we proposed a two - wheel stretch engine @xcite using a nematic photo - lce ..
Please generate the next two sentences of the article | the engine had analogies to that of steinberg _ et .
al _ who studied chemical to mechanical energy conversion @xcite . here , |
8,421 | Suppose that you have an abstract for a scientific paper: the isotopic dependence of the complete fusion ( capture ) cross section is analyzed in the reactions @xmath0xe+@xmath1ca with stable and radioactive beams .
it is shown for the first time that the very neutron - rich nuclei @xmath2w can be reached with relatively large cross sections by complete fusion reactions with radioactive ion beams at incident energies near the coulomb barrier .
a comparison between the complete fusion and fragmentation reactions for the production of neutron - rich w and neutron - deficient rn isotopes is performed . .
And you have already written the first three sentences of the full article: the new generation of radioactive ion beam facilities will provide high intensity ( @xmath3 ions / s ) exotic beams ( for example , @xmath4kr , @xmath5sn , @xmath6xe or @xmath7cs ) .
one of the most interesting areas of research with radioactive beams will be the study of the complete fusion process @xcite where the fusion experiments with exotic beams can be performed to synthesize and study new isotopes of existing elements .
the central issue is whether the capture and fusion cross sections will be enhanced due to the large deformation of the neutron - rich or neutron - deficient projectile - nucleus ..
Please generate the next two sentences of the article | however , one should bear in mind the smaller intensity of these beams in comparison with the intensity of stable beams .
our aim is to find the global trend in the production cross section of exotic nuclei as a function of the charge ( mass ) number of the projectile in complete fusion reactions . |
8,422 | Suppose that you have an abstract for a scientific paper: in this letter we apply a method recently devised in @xcite to find precise approximate solutions to a certain class of nonlinear differential equations .
the analysis carried out in @xcite is refined and results of much higher precision are obtained for the problems previously considered ( duffing equation , sextic oscillator ) .
fast convergence to the exact results is observed both for the frequency and for the fourier coefficients .
the method is also applied with success to more general polynomial potentials ( the octic oscillator ) and to the van der pol equation .
epsf .1 in .
And you have already written the first three sentences of the full article: in this letter we extend the analysis of @xcite , where a new method for the solution of oscillatory nonlinear problems was devised .
this method works by combining the lindstedt - poincar ( lp ) @xcite method to the linear delta expansion ( lde)@xcite , or optimized perturbation theory ( opt ) @xcite .
a detailed list of references on the lde can be found in @xcite ..
Please generate the next two sentences of the article | the lp method is used to solve approximately nonlinear differential equations with periodic solutions , by introducing strained coordinates , which allow to eliminate the secular terms arising in the perturbative expansion ; in the lde method an insoluble theory is interpolated with a soluble one depending on some arbitrary parameter : an expansion is then carried out in terms of a suitably defined `` perturbation '' . since the `` perturbation '' is not a priori fixed and not necessarily expressed in terms of `` small '' parameters , the method is truly nonperturbative . as proved in @xcite the application of lde to the lp method , which is at the core of our method , allows to extend the analysis to the nonperturbative regime ( large nonlinearities ) and to obtain errors which are small even in regimes where the lp method fails completely . in this letter
we pursue two goals : on one hand to investigate the convergence of our method in the cases previously analyzed to higher orders ; on the other hand to test the method by applying it to more demanding problems , such as the van der pol equation . |
8,423 | Suppose that you have an abstract for a scientific paper: we have studied the relevance of spin - orbit coupling to the dispersion relation of the larmor resonance observed in inelastic light scattering and electron - spin resonance experiments on gaas quantum wells .
we show that the spin - orbit interaction , here described by a sum of dresselhaus and bychkov - rashba terms , couples zeeman and spin - density excitations . we have evaluated its contribution to the spin splitting as a function of the magnetic field @xmath0 , and
have found that in the small @xmath0 limit , the spin - orbit interaction does not contribute to the spin splitting , whereas at high magnetic fields it yields a @xmath0 independent contribution to the spin splitting given by @xmath1 , with @xmath2 being the intensity of the bychkov - rashba and dresselhaus spin - orbit terms . .
And you have already written the first three sentences of the full article: the study of spin - orbit ( so ) effects in semiconductor nanostructures has been the object of many experimental and theoretical investigations in the last few years , see e.g. refs . and refs . therein .
it links the spin and the charge dynamics , hence opening the possibility of spin control by means of electric fields.@xcite it has been recently shown@xcite that the so interaction affects the optical properties of gaas quantum wells by inducing a coupling between charge density and spin density excitations in the long wavelength limit .
we extend here this study to the influence on the larmor resonance of the combined effect of both dresselhaus@xcite and bychkov - rashba@xcite so interactions , and use our results to discuss some features of the spin modes disclosed by inelastic light scattering@xcite and electron - spin resonance experiments.@xcite our approach is based on the solution of the equation of motion up to second order in the so intensity parameters.@xcite this method has been also used to derive the kohn theorem,@xcite and goes as follows ..
Please generate the next two sentences of the article | we write the schrdinger equation for a @xmath3-particle system as @xmath4 , with @xmath5 and @xmath6 being the ground state ( gs ) and gs energy , respectively .
if one can find an operator @xmath7 such that @xmath8 , @xmath9 , it is possible to cast the schrdinger equation into an operator equation -the equation of motion- @xmath10 = \omega_n o^+_n$ ] , where @xmath11 is the excitation energy of the state @xmath12 . |
8,424 | Suppose that you have an abstract for a scientific paper: let @xmath0 and @xmath1 be two hyperbolic finite area surfaces with cusps .
we show that for every @xmath2 there are finite degree unbranched covers @xmath3 and @xmath4 , such that the weil - petersson distance between @xmath5 and @xmath6 is less than @xmath7 in the corresponding moduli space . .
And you have already written the first three sentences of the full article: we say that a hyperbolic riemann surface is of finite type if it has the finite area with respect to the underlining hyperbolic metric .
such surfaces are either closed or are obtained from closed surfaces after removing at most finitely punctures .
all riemann surfaces in this paper are hyperbolic and of finite type ( except the unit disc / upper half space which is the universal cover of such surfaces ) ..
Please generate the next two sentences of the article | let @xmath0 and @xmath1 be two finite type riemann surfaces that are both either closed or both have at least one puncture .
then there is always a common holomorphic ( possibly branched ) cover of @xmath0 and @xmath1 . however a generic pair of such surfaces will not have a common holomorphic , unbranched finite degree cover . except the universal cover , from now on all covers in this paper |
8,425 | Suppose that you have an abstract for a scientific paper: a general analytical formula for recurrence relations of multisite interaction ising models in an external magnetic field on the cayley - type lattices is derived . using the theory of complex analytical dynamics on the riemann sphere , a numerical algorithm to obtain yang - lee and fisher zeros of the models is developed .
it is shown that the sets of yang - lee and fisher zeros are almost always fractals , that could be associated with mandelbrot - like sets on the complex magnetic field and temperature planes respectively . .
And you have already written the first three sentences of the full article: in 1952 , lee and yang in their famous papers @xcite first proposed a new and effective method for investigation of phase transitions .
they studied the distribution of zeros of the partition function considered as a function of a complex magnetic field ( fugacity ) , and proved the circle theorem , which states that the zeros of the partition function of ising ferromagnet lie on the unit circle in the complex fugacity plane ( _ yang - lee zeros _ ) . after these pioneer works of lee and yang , fisher @xcite , in 1964 , initiated the study of partition function zeros in the complex temperature plane ( _ fisher zeros _ ) .
these methods are then extended to other type of interactions and were widely applied @xcite ..
Please generate the next two sentences of the article | recently , binek @xcite showed that the density of yang - lee zeros can be determined experimentally from the field dependence of the isothermal magnetization data .
the fractal structure of fisher zeros in q - state potts model on the diamond lattice was obtained by derrida , seze and itzykson @xcite . |
8,426 | Suppose that you have an abstract for a scientific paper: when gene copies are sampled from various species , the resulting gene tree might disagree with the containing species tree .
the primary causes of gene tree and species tree discord include lineage sorting , horizontal gene transfer , and gene duplication and loss .
each of these events yields a different parsimony criterion for inferring the ( containing ) species tree from gene trees . with lineage sorting ,
species tree inference is to find the tree minimizing extra gene lineages that had to coexist along species lineages ; with gene duplication , it becomes to find the tree minimizing gene duplications and/or losses . in this paper , we show the following results : \(i ) the deep coalescence cost is equal to the number of gene losses minus two times the gene duplication cost in the reconciliation of a uniquely leaf labeled gene tree and a species tree .
the deep coalescence cost can be computed in linear time for any arbitrary gene tree and species tree .
\(ii ) the deep coalescence cost is always no less than the gene duplication cost in the reconciliation of an arbitrary gene tree and a species tree .
\(iii ) species tree inference by minimizing deep coalescences is np - hard .
* index terms : * reconciliation of gene tree and species , deep coalescence , gene duplication and loss , parsimony criterion , np - hardness . .
And you have already written the first three sentences of the full article: gene trees are fundamental to molecular systematics .
traditionally , a gene tree is reconstructed from dna sequence variation at individual genetic loci in a group of species and is taken as the phylogenetic tree of the species due to sequencing technology limitations . however , when gene copies are sampled from various species , the resulting gene tree might disagree with the species tree .
as such , the relationship between gene trees and species trees has been the focus of many studies ( see for example @xcite ) ..
Please generate the next two sentences of the article | it has long been recognized that gene trees can be used to estimate species divergence time , ancestral population sizes and even the containing species tree although they may not accurately reflect the species tree @xcite .
the discord of gene trees and the containing species tree can arise from horizontal gene transfer , lineage sorting , and gene duplication and loss . |
8,427 | Suppose that you have an abstract for a scientific paper: in this paper we present an interacting - agent model of speculative activity explaining bubbles and crashes in stock markets .
we describe stock markets through an infinite - range ising model to formulate the tendency of traders getting influenced by the investment attitude of other traders .
bubbles and crashes are understood and described qualitatively and quantitatively in terms of the classical phase transitions .
when the interactions among traders become stronger and reach some critical values , a second - order phase transition and critical behaviour can be observed , and a bull market phase and a bear market phase appear .
when the system stays at the bull market phase , speculative bubbles occur in the stock market . for a certain range of the external field that we shall call the investment environment , multistability and hysteresis phenomena
are observed .
when the investment environment reaches some critical values , the rapid changes in the distribution of investment attitude are caused .
the first - order phase transition from a bull market phase to a bear market phase is considered as a stock market crash .
furthermore we estimate the parameters of the model using the actual financial data . as an example of large crashes we analyse japan crisis ( the bubble and the subsequent crash in the japanese stock market in 1987 - 1992 ) , and
show that the good quality of the fits , as well as the consistency of the values of the parameters are obtained from japan crisis .
the results of the empirical study demonstrate that japan crisis can be explained quite naturally by the model that bubbles and crashes have their origin in the collective crowd behaviour of many interacting agents .
+ * keyword * speculative bubbles ; stock market crash ; phase transition ; mean field approximation ; japan crisis .
And you have already written the first three sentences of the full article: the booms and the market crashes in financial markets have been an object of study in economics and a history of economy for a long time .
economists @xcite , and economic historians @xcite , @xcite , @xcite have often suggested the importance of psychological factors and irrational factors in explaining historical financial euphoria . as keynes @xcite , a famous economist and outstandingly successful investor , acutely pointed out in his book , _ the general theory of employment , interest and money _ , stock price changes have their origin in the collective crowd behaviour of many interacting agents rather than fundamental values which can be derived from careful analysis of present conditions and future prospects of firms . in a recent paper published in the economic journal , lux
@xcite modelled the idea explicitly and proposed a new theoretical framework to explain bubbles and subsequent crashes which links market crashes to the phase transitions studied in statistical physics . in his model.
Please generate the next two sentences of the article | the emergence of bubbles and crashes is formalised as a self - organising process of infections among heterogeneous traders . in recent independent works , several groups of physicists @xcite , @xcite , @xcite , @xcite , @xcite , @xcite , @xcite , @xcite , @xcite , @xcite ,
@xcite proposed and demonstrated empirically that large stock market crashes , such as the 1929 and the 1987 crashes , are analogous to critical points . |
8,428 | Suppose that you have an abstract for a scientific paper: the seyfert 2 galaxy ngc 7674 has been observed within the bepposax core programme with the onboard narrow field instruments between 0.1 and 100 kev .
the broad - band spectrum shows four most relevant spectral components : a ) a soft excess below @xmath02 kev ; b ) a prominent ( ew@xmath01 kev ) fe line ; c ) a flat ( @xmath1 ) 210 kev continuum ; d ) a 4.5@xmath2 detection above 13 kev
. the flat power law spectrum can be very well explained within the current agn unified models assuming a steep ( @xmath3 ) intrinsic spectrum scattered by warm gas for the low energy band and totally reflected by optically thick cold matter ( plausibly a molecular torus ) for the high energy band .
the case of ngc 7674 adds to the increasing number of so called `` compton - thick '' seyfert 2 galaxies in which the direct emission is totally absorbed and the x - ray luminosity is thus at least one or two orders of magnitude larger than what inferred from the observed flux . .
And you have already written the first three sentences of the full article: unification models of seyfert galaxies , at least in their simplest formulation , postulate the presence of a geometrically and optically thick gas and dust torus which , at a distance of several to several tens of parsecs from the nucleus ( krolik , madau , and zycki 1994 ) , hides the primary source and the broad line forming region ( blr ) .
the orientation of the torus is independent of the host galaxy , and the observed differences between seyfert 1 and seyfert 2 nuclei are thus to be ascribed simply to the angle formed by the line of sight direction and the axis of the torus .
after the seminal work by antonucci & miller ( 1985 ) various pieces of evidence have been accumulating in favour of the unification model of seyfert galaxies ( see antonucci 1993 for a review of the subject ) : detection of broadened emission lines in optical spectropolarimetry observations of several seyfert 2 galaxies ( antonucci & miller 1985 ; miller & goodrich 1990 ; tran 1995 ; young et al ..
Please generate the next two sentences of the article | 1996 ) interpreted as scattering of the blr emission by warm material placed above the torus ; biconical structures in the light of the forbidden line at 5007 @xmath4 ( e.g. tadhunter and tsvetanov 1989 ) which is expected if the ionizing radiation field from the nucleus is anisotropic ; large ( @xmath5 @xmath6 or greater ) absorbing column densities observed in the hard x - ray spectra of seyfert 2 galaxies ( awaki 1997 ) . in the optical and uv bands
the nuclear emission is visible only if the line of sight does not intercept the torus . in the x - ray band , |
8,429 | Suppose that you have an abstract for a scientific paper: we describe a set of techniques for performing large scale _ ab initio _ calculations using multigrid accelerations and a real - space grid as a basis .
the multigrid methods provide effective convergence acceleration and preconditioning on all length scales , thereby permitting efficient calculations for ill - conditioned systems with long length scales or high energy cut - offs .
we discuss specific implementations of multigrid and real - space algorithms for electronic structure calculations , including an efficient multigrid - accelerated solver for kohn - sham equations , compact yet accurate discretization schemes for the kohn - sham and poisson equations , optimized pseudopotentials for real - space calculations , efficacious computation of ionic forces , and a complex - wavefunction implementation for arbitrary sampling of the brillioun zone .
a particular strength of a real - space multigrid approach is its ready adaptability to massively parallel computer architectures , and we present an implementation for the cray - t3d with essentially linear scaling of the execution time with the number of processors .
the method has been applied to a variety of periodic and non - periodic systems , including disordered si , a n impurity in diamond , aln in the wurtzite structure , and bulk al . the high accuracy of the atomic forces allows for large step molecular dynamics ; e.g. , in a 1 ps simulation of si at 1100 k with an ionic step of 80 a.u .
, the total energy was conserved within 27 @xmath0ev per atom . .
And you have already written the first three sentences of the full article: over the last several decades algorithmic advances coupled with the development of high speed supercomputers , have made _ ab initio _ quantum mechanical simulations possible for a wide range of physical systems .
these methods have been used to provide a theoretical framework for interpreting experimental results and even to accurately predict the material properties before experimental data were available .
however , the calculations are currently restricted to systems containing a few hundred atoms.@xcite this limitation is set by the available computer power , and the scaling of the computational work with the number of atoms ..
Please generate the next two sentences of the article | one of the most successful of the recent techniques is the car - parrinello method@xcite in which the electronic orbitals are expanded in plane - wave basis functions and the resulting hamiltonian is iteratively diagonalized .
the practical and efficient extension of _ ab initio _ quantum methods to larger and more difficult systems may be accomplished by the refinement and improvement of traditional methods or by the development of new techniques . although highly successful , traditional plane - wave methods encounter considerable difficulties when they are applied to physical systems with large length scales , or containing first - row or transition - metal atoms . |
8,430 | Suppose that you have an abstract for a scientific paper: in recent years , consumer unmanned aerial vehicles have become very popular , everyone can buy and fly a drone without previous experience , which raises concern in regards to regulations and public safety . in this paper , we present a novel approach towards enabling safe operation of such vehicles in urban areas .
our method uses geodetically accurate dataset images with geographical information system ( gis ) data of road networks and buildings provided by google maps , to compute a weighted a * shortest path from start to end locations of a mission .
weights represent the potential risk of injuries for individuals in all categories of land - use , i.e. flying over buildings is considered safer than above roads .
we enable safe uav operation in regards to 1- land - use by computing a static global path dependent on environmental structures , and 2- avoiding flying over moving objects such as cars and pedestrians by dynamically optimizing the path locally during the flight .
as all input sources are first geo - registered , pixels and gps coordinates are equivalent , it therefore allows us to generate an automated and user - friendly mission with gps waypoints readable by consumer drones autopilots .
we simulated 54 missions and show significant improvement in maximizing uav s standoff distance to moving objects with a quantified safety parameter over 40 times better than the naive straight line navigation . .
And you have already written the first three sentences of the full article: uavs are becoming increasingly present in our everyday lives , their extensive use recently jumped from military to hobby and professional applications .
the consumer market is growing and now it offers a wide range of micro and mini uavs at affordable costs . but this popularity induces some dangerous behavior , most people do not realize that a simple mistake can cause severe injuries to themselves or others.in the united - states , the faa has taken measures to inform hobbyists and encourage them to follow a code of conduct to prevent accidents .
the only form available is the advisory circular ac 91 - 57 from june 9th 1981 , it advises pilots to keep their uavs within their line of sight , below 400 feet above ground level , further than 5 miles from an airport ( or warn them ) , and to avoid flying above people.even for the vast majority of uav users that are responsible and careful in their use , there is no automated means to fly safely in regards to the uav s environment ..
Please generate the next two sentences of the article | our work aims to provide such functionality to micro and mini uavs that are operated in urban areas . in this paper
, we propose a novel method for autonomous navigation for low - altitude uavs in urban areas . for a given mission |
8,431 | Suppose that you have an abstract for a scientific paper: we propose a scheme for perfect transfer of an unknown qubit state via the discrete - time quantum walk on a line or a circle . for this purpose
, we introduce an additional coin operator which is applied at the end of the walk .
this operator does not depend on the state to be transferred .
we show that perfect state transfer over an arbitrary distance can be achieved only if the walk is driven by an identity or a flip coin operator .
other biased coin operators and hadamard coin allow perfect state transfer over finite distances only .
furthermore , we show that quantum walks ending with a perfect state transfer are periodic .
january 2015 _ keywords _ : quantum walk , quantum state transfer , quantum state revival .
And you have already written the first three sentences of the full article: quantum state transfer from one location to another is a significant problem for quantum information processing systems .
a quantum computer , which consists of different processing units , requires the quantum states to be transferred between its parts .
therefore , quantum state transfer will be an important part of quantum computer design ..
Please generate the next two sentences of the article | there are various ways of achieving this task depending on the technology at hand @xcite . in this article , we consider two related fields of research , quantum state transfer and quantum walks on one - dimensional lattices .
quantum communication through a spin chain was first considered by bose @xcite and since then it has been studied in depth @xcite . |
8,432 | Suppose that you have an abstract for a scientific paper: we propose an elaborate version of the hadron resonance gas model with the combined treatment of separate chemical freeze - outs for strange and non - strange hadrons and with an additional @xmath0 factor which accounts for the remaining strange particle non - equilibration .
two sets of chemical freeze - outs parameters are connected by the conservation laws of entropy , baryonic charge , isospin projection and strangeness .
the developed approach enables us to perform a high - quality fit of the hadron multiplicity ratios for ags , sps and rhic energies with total @xmath1 1.05 .
a special attention is paid to a complete description of the strangeness horn .
a well - known @xmath2 , @xmath3 and @xmath4 selective suppression problem is also discussed . .
And you have already written the first three sentences of the full article: relativistic a+a collisions are an important source of experimental information about the qcd phase diagram and the strongly interacting matter properties . the last stage of such collisions is traditionally analyzed within the statistical approach which gives us an excellent opportunity to reveal the parameters of chemical freeze - out .
this approach is based on the assumption of the thermal equilibrium existence during the last stage of reaction .
such an equilibrium can be reached due to intensive particle scattering ..
Please generate the next two sentences of the article | the stage of the system evolution when the inelastic reactions between hadrons stop is referred to as a chemical freeze - out ( fo ) .
particle yields are determined by the parameters of fo , namely by chemical potentials and temperature . |
8,433 | Suppose that you have an abstract for a scientific paper: cellular signaling involves the transmission of environmental information through cascades of stochastic biochemical reactions , inevitably introducing noise that compromises signal fidelity .
each stage of the cascade often takes the form of a kinase - phosphatase push - pull network , a basic unit of signaling pathways whose malfunction is linked with a host of cancers .
we show this ubiquitous enzymatic network motif effectively behaves as a wiener - kolmogorov ( wk ) optimal noise filter . using concepts from umbral calculus ,
we generalize the linear wk theory , originally introduced in the context of communication and control engineering , to take nonlinear signal transduction and discrete molecule populations into account .
this allows us to derive rigorous constraints for efficient noise reduction in this biochemical system .
our mathematical formalism yields bounds on filter performance in cases important to cellular function like ultrasensitive response to stimuli .
we highlight features of the system relevant for optimizing filter efficiency , encoded in a single , measurable , dimensionless parameter .
our theory , which describes noise control in a large class of signal transduction networks , is also useful both for the design of synthetic biochemical signaling pathways , and the manipulation of pathways through experimental probes like oscillatory input .
extracting signals from time series corrupted by noise is a challenge in a number of seemingly unrelated areas .
minimizing the effects of noise is a critical consideration in designing communication and navigation systems , and analyzing data in diverse fields like medical and astronomical imaging .
more recently , a number of studies have focused on how biological circuits , comprised of chemical signaling pathways mediated by genes , proteins , and rna , cope with noise @xcite .
one of the key discoveries in the past decade is that the naturally occurring systems that control all aspects of cellular processes....
And you have already written the first three sentences of the full article: * theoretical framework for a minimal signaling circuit . * to obtain the central results , we start with an example which illustrates the efficacy of the wk theory , and suggests a way to a more detailed , realistic model of the enzymatic push - pull loop . consider a small portion of a signaling pathway [ fig .
[ f1]c ] , involving two chemical species : one with time - varying population @xmath0 ( the `` input '' ) , and another one with population @xmath1 ( the `` output '' ) whose production depends on @xmath0 .
these could be , for example , the active , phosphorylated forms of two kinases within a signaling cascade , with @xmath2 downstream of @xmath3 ..
Please generate the next two sentences of the article | the upstream part of the pathway contributes an effective production rate @xmath4 for species @xmath3 , which in general can be time - dependent , though for now we will make @xmath4 constant .
the output @xmath2 is produced by a reaction , @xmath5 , with a rate @xmath6 that depends on the input . |
8,434 | Suppose that you have an abstract for a scientific paper: we study the inspiral , merger and ringdown of unequal mass black hole binaries by analyzing a catalogue of numerical simulations for seven different values of the mass ratio ( from @xmath0 to @xmath1 ) .
we compare numerical and post - newtonian results by projecting the waveforms onto spin - weighted spherical harmonics , characterized by angular indices @xmath2 .
we find that the post - newtonian equations predict remarkably well the relation between the wave amplitude and the orbital frequency for each @xmath2 , and that the convergence of the post - newtonian series to the numerical results is non - monotonic . to leading order
the total energy emitted in the merger phase scales like @xmath3 and the spin of the final black hole scales like @xmath4 , where @xmath5 is the symmetric mass ratio .
we study the multipolar distribution of the radiation , finding that odd-@xmath6 multipoles are suppressed in the equal mass limit .
higher multipoles carry a larger fraction of the total energy as @xmath7 increases .
we introduce and compare three different definitions for the ringdown starting time . applying linear estimation methods ( the so - called prony methods ) to the ringdown phase , we find resolution - dependent time variations in the fitted parameters of the final black hole . by cross - correlating information from different multipoles
we show that ringdown fits can be used to obtain precise estimates of the mass and spin of the final black hole , which are in remarkable agreement with energy and angular momentum balance calculations . .
And you have already written the first three sentences of the full article: more than thirty years after the first numerical simulations of binary black hole dynamics , the numerical relativity community is finally ready to compare binary black hole simulations with experimental data .
thanks to a series of recent breakthroughs , long term evolutions of inspiralling binary black holes that last for more than one orbit have been obtained with several independent codes , and accurate gravitational wave signals have been computed @xcite .
the use of numerical waveforms as templates for gravitational wave detection requires large - scale parameter studies , and correspondingly large computational resources ..
Please generate the next two sentences of the article | the main current technical problems in the field are the efficiency of the numerical simulations and the development of a `` data analysis pipeline '' , connecting numerical simulations with analytical calculations of the early inspiral and late ringdown phases , and ( eventually ) with gravitational wave searches in actual detector data . to build a common language between the numerical relativity and data analysis communities
we must develop a deeper understanding of the physical content of the simulations using analytical techniques , such as post - newtonian ( pn ) theory and black hole perturbation theory . |
8,435 | Suppose that you have an abstract for a scientific paper: in a study of _ chandra _ high energy transmission grating spectra of algol , we clearly detect doppler shifts caused by the orbital motion of algol b. these data provide the first definitive proof that the x - ray emission of algol is dominated by the secondary , in concordance with expectations that the primary b8 component should be x - ray dark
. however , the measured doppler shifts are slightly smaller than might be expected , implying an effective orbital semi - major axis of about @xmath0 instead of @xmath1 for the algol b center of mass .
this could be caused by a small contribution of algol a , possibly through accretion , to the observed x - ray flux , in which case such a contribution does not exceed 10 - 15% .
we suggest the more likely explanation is an asymmetric corona biased toward the system center of mass by the tidal distortion of the surface of algol b. a detailed analysis of the profiles of the strongest lines indicates the presence of excess line broadening amounting to approximately 150 km s@xmath2 above that expected from thermal motion and surface rotation .
possible explanations for this additional broadening include turbulence , flows or explosive events , or rotational broadening from a radially extended corona .
we favor the latter scenario and infer that a significant component of the corona at temperatures @xmath3 k has a scale height of order the stellar radius .
this interpretation is supported by the shape of the x - ray lightcurve and tentative detection of a shallow dip at secondary eclipse .
we also examine the o vii intercombination and forbidden lines in a low energy transmission grating spectrograph observation and find no change in their relative line fluxes as the system goes from quadrature to primary eclipse . since these lines appear to be strongly affected by uv irradiation from algol a through radiative excitation of the @xmath4 transition , this supports the conjecture that the corona of algol b at temperatures of several million k must....
And you have already written the first three sentences of the full article: algol ( @xmath5 perseus ) is the eponymous eclipsing binary system which consists of a primary early - type main sequence star and a roche lobe - filling secondary late - type giant or subgiant star .
these systems have undergone a period of mass transfer during which material was transferred from the initially more massive present day late - type star to its initially less massive early - type companion .
algol is the brightest and nearest example of this type ..
Please generate the next two sentences of the article | the primary star ( algol a ) is a b8 v main sequence star , while the secondary ( algol b ) is a k2 iv subgiant that has lost about half of its original mass to the present day primary ( e.g. , * ? ? ?
* ) . since algol has a short period orbit of 2.87 days ( e.g. , * ? ? ? |
8,436 | Suppose that you have an abstract for a scientific paper: recently a new technique for the production of muon ( @xmath0 ) and muonium ( @xmath1 ) beams of unprecedented brightness has been proposed .
as one consequence and using a highly stable mach - zehnder type interferometer , a measurement of the gravitational acceleration @xmath2 of muonium atoms at the few percent level of precision appears feasible within 100days of running time .
the inertial mass of muonium is dominated by the mass of the positively charged - antimatter - muon .
the measurement of @xmath2 would be the first test of the gravitational interaction of antimatter , of a purely leptonic system , and of particles of the second generation .
the gravitational acceleration of antimatter has not been measured so far .
an experiment with antiprotons ( see @xcite and references therein ) did not succeed because of the extreme difficulty to sufficiently shield the interaction region from electromagnetic fields . for a similar reason , results of measurements with electrons @xcite are discussed very controversial and the plan to eventually compare with positrons was never realized . not affected by these problems are neutral systems like antihydrogen and , consequently , considerable effort today is devoted to the preparation of suitable samples of antihydrogen ( compare @xcite ) . a possibility to measure
the effect of gravitation on neutral particles is via a phase acquired in the gravitational potential in a suitably built interferometer , demonstrated in the classic colella
overhauser werner ( cow ) experiment @xcite . in case of limited source performance ,
when one has to deal with extended sources , comparatively large beam divergence and poor energy definition , mach - zehnder type interferometers have striking advantages @xcite
. their performance has been demonstrated , among others , with neutrons @xcite and atoms @xcite .
the idea to apply interferometry to the measurement of an antimatter system was inspired by the cow - experiments and dates back , as far as....
And you have already written the first three sentences of the full article: i am indebted to l. m. simons who , inspired by the colella - overhauser - werner experiments , put forward the idea of measuring the gravitational interaction of antimatter with a mach - zehnder interferometer at a conference in the 1980s .
he has also repeatedly argued that muonium would be almost completely antimatter and thus be a reasonable target for an experimental test of its gravitational interaction - suffering only from insufficient source strength .
i am also thankful to d. taqqu for discussions and explanations concerning the production of a suitable muonium beam ..
Please generate the next two sentences of the article | |
8,437 | Suppose that you have an abstract for a scientific paper: we show the first lattice qcd results on the axial charges @xmath0 of @xmath1 and @xmath2 .
the measurements are performed with two flavors of dynamical quarks employing the renormalization - group improved gauge action at @xmath3=1.95 and the mean - field improved clover quark action with the hopping parameters , @xmath4=0.1375 , 0.1390 and 0.1400 .
we construct 2@xmath52 correlation matrices and diagonalize them so that the signals of @xmath1 and @xmath2 are properly separated .
wraparound contributions in the correlator , which can be another source of signal contaminations , are eliminated by imposing the dirichlet boundary condition in the temporal direction .
the axial charge of @xmath1 is found to take small values as @xmath6 , whereas that of @xmath2 is approximately 0.5 , which is almost independent of quark masses and consistent with the predictions by the naive nonrelativistic quark model . .
And you have already written the first three sentences of the full article: chiral symmetry together with its spontaneous breaking is one of the key ingredients in the low - energy hadron or nuclear physics . due to its spontaneous
breaking , up and down quarks , whose current masses are of the order of a few mev , acquire the large constituent masses of a few hundreds mev , and are consequently responsible for about 99% of mass of the nucleon and hence that of our world .
one would thus consider that chiral condensate @xmath7 , the order parameter of the chiral phase transition , plays an essential role in the hadron - mass genesis in the light quark sector . on the other hand ,.
Please generate the next two sentences of the article | chiral symmetry gets restored in systems where hard external energy scales such as high - momentum transfer , temperature(@xmath8 ) , baryon density and so on exist , owing to the asymptotic freedom of qcd .
then , several questions may arise : are all hadronic modes massless in such systems ? can hadrons be massive even without non - vanishing chiral condensate ? |
8,438 | Suppose that you have an abstract for a scientific paper: we present the measurements of the leptonic asymmetries in @xmath0 decays measured by the sld experiment at slac .
a data sample of approximately 550,000 @xmath0 bosons are used for the preliminary measurement of @xmath1 and the leptonic final state measurements of @xmath2 , @xmath3 and @xmath4 , representing the entire set of 1992 - 1998 sld runs .
when combining all results , a preliminary value for the effective weak mixing angle is obtained : @xmath5 .
we also present the direct measurements of @xmath6 from left - right forward - backward asymmetries , using partial data samples from 1993 - 1998 sld runs .
the preliminary value combines jet charge , cascade kaon and semileptonic decay analyses to obtain @xmath7 . .
And you have already written the first three sentences of the full article: the slc linear electron - positron collider@xcite has long been a powerful facility for testing the standard model via measurements of electroweak couplings at the @xmath0 pole .
its unique attributes of a highly longitudinally polarized electron beam ( @xmath8% ) and small spot size ( 1.5 x 0.8 x 700 ) @xmath9m@xmath10 in ( x , y , z ) have recently been augmented by improved luminosity for the 1997 - 1998 sld run and these have proved advantageous for precision electroweak measurements .
the sld detector@xcite is designed to take advantage of these special attributes of the slc . the polarized differential cross section at born level for the process.
Please generate the next two sentences of the article | , @xmath11 is given by : @xmath12 where @xmath13 is the final state coupling , @xmath14 is the electron beam polarization ( @xmath15 for right - handed beams ) , @xmath16 where @xmath17 is the angle of the final state fermion with respect to the electron beam axis , and @xmath18 and @xmath19 are the vector and axial vector couplings which specify the z - f coupling
. one can define the left right asymmetry which equals the initial state coupling asymmetry @xmath2 , @xmath20 } = a_{e } \label{eqn : alr } \end{aligned}\ ] ] although one can use all final states to build the asymmetry , in practice , our cuts select hadronic final states : leptonic final states are treated separately ( see section iv ) . if @xmath14 can be measured precisely , then @xmath21 provides us with an effective way to measure @xmath22 : @xmath23 where the evolution of @xmath24 signifies the convention of making eqn . |
8,439 | Suppose that you have an abstract for a scientific paper: adaptive optics observations in the infrared ( vlt / naco , kervella et al . 2014 ) and
visible ( vlt / sphere , kervella et al . 2015 ) domains revealed that the nearby agb star l@xmath0 pup ( @xmath1pc ) is surrounded by a dust disk seen almost edge - on .
thermal emission from a large dust `` loop '' is detected at 4@xmath2 m up to more than 10au from the star .
we also detect a secondary source at a separation of 32mas , whose nature is uncertain .
l@xmath0 pup is currently a relatively `` young '' agb star , so we may witness the formation of a planetary nebula .
the mechanism that breaks the spherical symmetry of mass loss is currently uncertain , but we propose that the dust disk and companion are key elements in the shaping of the bipolar structure .
l@xmath0 pup emerges as an important system to test this hypothesis . .
And you have already written the first three sentences of the full article: the final stages of the evolution of low and intermediate mass stars involve complex and poorly understood physical phenomena that lead to the formation of axially symmetric bipolar planetary nebulae ( pne ) .
the origin of these spectacular structures is generally associated to interactions between the material expelled from the evolved star and an orbiting companion ( lagagec & chesneau @xcite ; soker & livio @xcite ) . the presence of a circumstellar disk is also invoked to collimate mass loss and foster the appearance of the axial symmetry , but such disks have only been observed in a few evolved stars .
l@xmath0 pup ( hd56096 ) is one of the nearest ( @xmath3 , van leeuwen @xcite ) and brightest ( @xmath4 , @xmath5 ) asymptotic giant branch ( agb ) star that exhibits mira - like pulsations with a period of 141days ( bedding et al ..
Please generate the next two sentences of the article | this star is particularly interesting as kervella et al .
( @xcite ) discovered a circumstellar disk around l@xmath0pup using adaptive optics in the near - infrared . |
8,440 | Suppose that you have an abstract for a scientific paper: while bayesian methods are praised for their ability to incorporate useful prior knowledge , in practice , priors that allow for computationally convenient or tractable inference are more commonly used . in this paper , we investigate the following question : _ for a given model , is it possible to use any convenient prior to infer a false posterior , and afterwards , given some true prior of interest , quickly transform this result into the true posterior ? _ we present a procedure to carry out this task : given an inferred false posterior and true prior , our algorithm generates samples from the true posterior .
this transformation procedure , which we call `` prior swapping '' works for arbitrary priors .
notably , its cost is independent of data size .
it therefore allows us , in some cases , to apply significantly less - costly inference procedures to more - sophisticated models than previously possible .
it also lets us quickly perform any additional inferences , such as with updated priors or for many different hyperparameter settings , without touching the data .
we prove that our method can generate asymptotically exact samples , and demonstrate it empirically on a number of models and priors . .
And you have already written the first three sentences of the full article: there are many cases in bayesian modeling where a certain choice of prior distribution allows for computationally simple or tractable inference .
for example , * conjugate priors yield posteriors with a known parametric form and therefore allow for non - iterative , exact inference @xcite . *
certain priors yield models with tractable conditional or marginal distributions , which allows efficient approximate inference algorithms to be applied ( e.g. gibbs sampling @xcite , sampling in collapsed models @xcite , or mean - field variational methods @xcite ) ..
Please generate the next two sentences of the article | * simple parametric priors ( e.g. the normal distribution ) allow for computationally cheap density queries , maximization , and sampling @xcite , which can allow for easier use in iterative inference algorithms ( e.g. metropolis - hastings @xcite , gradient - based mcmc @xcite , or sequential monte carlo @xcite ) . *
certain priors mitigate issues of identifiability , and allow for simpler posteriors without multiple modes @xcite . |
8,441 | Suppose that you have an abstract for a scientific paper: we investigate the influence of modified nuclear parton distribution functions ( pdfs ) on high- hadron production at rhic and lhc energies using a pqcd - improved parton model . for application at rhic , we focus on the possible contribution of the emc modification of the nuclear pdfs in the @xmath0 region to the observed suppression of production at @xmath1 gev / c in collisions .
we study three different parameterizations of the nuclear pdf modifications and find that they give consistent results for for neutral pions in the region @xmath2 gev / c @xmath3 gev / c .
we find that the emc suppression of the parton distributions in the @xmath4 nucleus does not strongly influence the for in the region where the suppression is observed .
using the hkn parameterization , we evaluate systematic errors in the theoretical resulting from uncertainties in the nuclear pdfs .
the measured nuclear modification factor is inconsistent with the pqcd model result for @xmath1 gev / c even when the systematic uncertainties in the nuclear pdfs are accounted for .
the inclusion of a small final - state energy loss can reduce the discrepancy with the data , but we can not perfectly reproduce the dependence of the measured . for the lhc , we find that shadowing of the nuclear pdfs produces a large suppression in the yield of hadrons with @xmath5 gev / c in @xmath6 collisions . .
And you have already written the first three sentences of the full article: deuteron - gold ( ) collisions have been extensively studied at the relativistic heavy ion collider ( rhic ) , both for their intrinsic interest and as a control experiment @xcite to judge the suppression seen in central gold - gold ( ) collisions at sufficiently high transverse momenta ( @xmath7 ) @xcite .
unexpectedly , not only data , but recent extended @xmath7 coverage data also display a suppressed nuclear modification factor in central collisions@xcite .
this motivates a study of possible mechanisms that may result in a nuclear modification factor smaller than unity at sufficiently high transverse momenta ( @xmath8 gev / c ) in central collisions ..
Please generate the next two sentences of the article | the nuclear modification factor @xmath9 compares the spectra of produced particles in collisions to a hypothetical scenario in which the nuclear collisions are assumed to be a superposition of the appropriate number of nucleon - nucleon collisions . in the transverse momentum window @xmath10
gev / c @xmath11 gev / c , the nuclear modification factors are dominated by the cronin peak @xcite . |
8,442 | Suppose that you have an abstract for a scientific paper: results of the computer simulation of dilepton production from the expanding pion gas created in ultrarelativistic pb+pb 160 gev / n collisions are presented . finite size of the expanding pion gas influences invariant mass spectrum of dileptons .
sensitivity of the shape of dilepton mass spectrum to the initial stage of the pion gas is discussed .
second order asymmetry in azimuthal distribution of dileptons is predicted for non - central collisions .
non - equilibrium nature of the pion gas expansion is found to exhibit itself in rapidity distribution of produced dilepton pairs .
= 7.2pt = 7.2pt + + + + 0.75 cm _ peter filip _
+ 0.35 cm _ institute of physics , slovak academy of sciences , sk 84228 + 0.15 cm faculty of mathematics and physics , comenius university , sk 84215 + 0.15 cm bratislava , slovak republic _ + .
And you have already written the first three sentences of the full article: goal of heavy ion collision ( hic ) experiments is to reveal properties of the compressed hot nuclear matter created during the collision of heavy nuclei .
final momentum distributions of most abundant particles - hadrons are however influenced ( if not determined ) during the dilute and late freeze - out stage of the heavy ion collision .
interesting information about the early stage of the collision is in this case hidden by subsequent collective effects of strongly interacting hadrons . fortunately other particles - leptons and photons produced in all stages of hic process , are not influenced by the later hadronic phase ..
Please generate the next two sentences of the article | thus distributions of leptons and photons can provide us with more or less direct information about the early stages of the collision process .
recent experimental results on invariant mass distribution of dilepton pairs @xcite have attracted increased attention due to the observed excess of dilepton yield at regions @xmath0gev ( na50 ) and @xmath1 gev ( ceres ) . theoretical analysis on dilepton pair production @xcite leads to the conclusion that unconventional production mechanisms ( e.g. modified @xmath2-meson mass @xcite or in - medium pion dispersion relation @xcite ) are necessary to explain present experimental data . in this contribution |
8,443 | Suppose that you have an abstract for a scientific paper: we describe a systematic approach to construct coarse - grained markov state models from molecular dynamics data of systems driven into a non - equilibrium steady state .
we apply this method to study the globule - stretch transition of a single tethered model polymer in shear flow .
the folding / unfolding rates of the coarse - grained model agree with the original detailed model .
we demonstrate that the folding / unfolding proceeds through the same narrow region of configuration space but along different cycles . .
And you have already written the first three sentences of the full article: computer simulations have developed into a powerful tool to predict and optimize material properties . however , even given the ever increasing computational power , relevant time and length scales , in particular for biological and synthetic macromolecules @xcite , will remain prohibitively long for fully atomistic simulations , and multiscale methods are crucial to make progress .
while structure - based coarse - graining @xcite has been quite successful @xcite , challenges remain like transferability ( _ e.g. _ , from bulk to surfaces ) , and in particular the correct treatment ( or _ a posteriori _ deduction ) of the materials _ dynamical _ properties through the coarse - grained dynamics . for the latter , markov state models ( msms )
@xcite have been used successfully to tackle the evolution of large proteins towards their native state , bridging the gap from molecular dynamics on nanoseconds to folding on milliseconds @xcite ..
Please generate the next two sentences of the article | the dynamics of msms is a discrete - time master equation with transition probabilities obey detailed balance on a network of long - lived ( metastable ) mesostates . here
we describe a systematic approach to construct msms with dynamics that break detailed balance . |
8,444 | Suppose that you have an abstract for a scientific paper: we present initial results from the wide - field infrared survey explorer ( wise ) , a four - band all - sky thermal infrared survey that produces data well suited to measuring the physical properties of asteroids , and the neowise enhancement to the wise mission allowing for detailed study of solar system objects . using a neatm thermal model fitting routine we compute diameters for over 100,000 main belt asteroids from their ir thermal flux , with errors better than @xmath0 .
we then incorporate literature values of visible measurements ( in the form of the h absolute magnitude ) to determine albedos . using these data
we investigate the albedo and diameter distributions of the main belt .
as observed previously , we find a change in the average albedo when comparing the inner , middle , and outer portions of the main belt .
we also confirm that the albedo distribution of each region is strongly bimodal .
we observe groupings of objects with similar albedos in regions of the main belt associated with dynamical breakup families .
asteroid families typically show a characteristic albedo for all members , but there are notable exceptions to this .
this paper is the first look at the main belt asteroids in the wise data , and only represents the preliminary , observed raw size and albedo distributions for the populations considered .
these distributions are subject to survey biases inherent to the neowise dataset and can not yet be interpreted as describing the true populations ; the debiased size and albedo distributions will be the subject of the next paper in this series . .
And you have already written the first three sentences of the full article: since the discovery of ( 1 ) ceres in 1801 @xcite the majority of observations of asteroids and other minor planets have been conducted in visible wavelengths . while visible light can provide very accurate positions , the interpretation of photometry is rendered ambiguous by the dependence of the observed flux on both the size and albedo of the asteroid .
this relationship is described by the equation : @xmath1 ( see * ? ? ? * for an overview and references therein for its derivation ) , where @xmath2 is the diameter in kilometers , @xmath3 is the visible geometric albedo , and @xmath4 is the absolute magnitude which is defined as the apparent magnitude the body would have @xmath5au from the sun , @xmath5au from the observer , and at @xmath6 phase angle .
albedos of solar system objects are observed to vary from only a few percent up to nearly @xmath7 percent for icy surfaces , causing diameters inferred from visible data alone to have nearly an order of magnitude uncertainty ..
Please generate the next two sentences of the article | multiwavelength visible surveys have found statistical correlations between the albedos and the visible colors of asteroids ( e.g. * ? ? ?
* ) , however the accuracy of the mapping between these two properties for individual objects is currently being examined @xcite . using an independent method of measurement for either the albedo or the diameter allows for the unique solution of the other , given a visible @xmath4 value . |
8,445 | Suppose that you have an abstract for a scientific paper: neutron - star mergers are interesting for several reasons : they are proposed as the progenitors of short gamma - ray bursts , they have been speculated to be a site for the synthesis of heavy elements , and they emit gravitational waves possibly detectable at terrestrial facilities .
the understanding of the merger process , from the pre - merger stage to the final compact object - accreting system involves detailed knowledge of numerical relativity and nuclear physics . in particular , key ingredients for the evolution of the merger are neutrino physics and the matter equation of state .
we present some aspects of neutrino emission from binary neutron star mergers showing the impact that the equation of state has on neutrinos and discuss some spectral quantities relevant to their detection such as energies and luminosities far from the source . .
And you have already written the first three sentences of the full article: together with gravity neutrinos drive the evolution of several stellar phenomena such as supernovae , binary mergers , and black hole accretion disks .
they are also a key ingredient in the synthesis of heavy elements @xcite , the production of gamma ray bursts @xcite and kilonova @xcite . despite the numerous efforts to fully understand these phenomena there are still puzzles to address .
unrevealing the missing pieces requires complex and computationally expensive simulations of the system under study that bring together details of nuclear physics and gravity ..
Please generate the next two sentences of the article | furthermore , due to the complexity of the problem , it is necessary to post - process the results to shed light on other derived aspects such as the element abundances and neutrino detection . the strong gravitational field generated by a binary neutron star merger changes the spectral properties of the emerging neutrinos .
this will affect any physical quantity related to them . |
8,446 | Suppose that you have an abstract for a scientific paper: we revisit the probabilistic construction of sparse random matrices where each column has a fixed number of nonzeros whose row indices are drawn uniformly at random .
these matrices have a one - to - one correspondence with the adjacency matrices of lossless expander graphs .
we present tail bounds on the probability that the cardinality of the _ set of neighbors _ for these graphs will be less than the expected value .
the bounds are derived through the analysis of collisions in unions of sets using a _
dyadic splitting _ technique .
this analysis led to the derivation of better constants that allow for quantitative theorems on existence of lossless expander graphs and hence the sparse random matrices we consider and also quantitative compressed sensing sampling theorems when using sparse non mean - zero measurement matrices .
-5 mm .
And you have already written the first three sentences of the full article: sparse matrices are particularly useful in applied and computational mathematics because of their low storage complexity and fast implementation as compared to dense matrices . of late
, significant progress has been made to incorporate sparse matrices in compressed sensing , with @xcite giving both theoretical performance guarantees and also exhibiting numerical results that shows sparse matrices coming from expander graphs can be as good sensing matrices as their dense counterparts .
in fact , blanchard and tanner @xcite recently demonstrated in a gpu implementation how well these type of matrices do compared to dense gaussian and discrete cosine transform matrices even with very small fixed number of nonzeros per column ( as considered here ) . in this manuscript.
Please generate the next two sentences of the article | we consider random sparse matrices that are adjacency matrices of lossless expander graphs .
expander graphs are highly connected graphs with very sparse adjacency matrices , a precise definition of a lossless expander graph is given in definition [ def : expander ] . |
8,447 | Suppose that you have an abstract for a scientific paper: we present the magnetic properties of complete solid solutions of zncr@xmath0o@xmath1 and cocr@xmath0o@xmath1 : two well - studied oxide spinels with very different magnetic ground states .
zncr@xmath0o@xmath1 , with non - magnetic @xmath2 cations occupying the a site and magnetic @xmath3 cations on the b site , is a highly frustrated antiferromagnet .
cocr@xmath0o@xmath1 , with magnetic @xmath4 cations ( three unpaired electrons ) on the a site as well , exhibits both nel ferrimagnetism as well as commensurate and incommensurate non - collinear magnetic order .
more recently , cocr@xmath0o@xmath1 has been studied extensively for its polar behavior which arises from conical magnetic ordering . gradually introducing magnetism on the a site of zncr@xmath0o@xmath1 results in a transition from frustrated antiferromagnetism to glassy magnetism at low concentrations of co , and eventually to ferrimagnetic and conical ground states at higher concentrations .
real - space monte - carlo simulations of the magnetic susceptibility suggest that the first magnetic ordering transition and features of the susceptibility across @xmath5 are captured by near - neighbor self- and cross - couplings between the magnetic a and b atoms .
we present as a part of this study , a method for displaying the temperature dependence of magnetic susceptibility in a manner which helps distinguish between compounds possessing purely antiferromagnetic interactions from compounds where other kinds of ordering are present . .
And you have already written the first three sentences of the full article: geometrically frustrated spin systems@xcite have been extensively investigated because of the fascinating fundamental physics they display .
more recently , they have attracted interest due to their frequently possessing ground states with spiral magnetic structures.@xcite recent interest in such structures has been engendered by the rediscovery of systems where the magnetic ordering does not have a center of symmetry , and there is perforce a loss of a center of symmetry in the crystal structure as well .
this helps to couple lattice and spin degrees of freedom and gives rise to a plethora of magnetoelectric phenomena.@xcite the spinel structure type ( displayed in figure[fig : struc ] ) with the general formula ab@xmath0x@xmath1 , has been extensively studied in this light because of its ability to host magnetic cations on both its tetrahedrally coordinated a sublattice as well as its octahedrally coordinated b sublattice ..
Please generate the next two sentences of the article | additionally , both sublattices are geometrically frustrated with octahedral b sites forming a pyrochlore network , and the tetrahedral sites forming a diamond lattice .
the former intrinsically displays geometric magnetic frustration associated with the difficulty of decorating the vertices of a tetrahedra with spins that are antialigned . |
8,448 | Suppose that you have an abstract for a scientific paper: we summarize our latest developments in perturbative treating the effective theories of strong interactions .
we discuss the principles of constructing the mathematically correct expressions for the s - matrix elements at a given loop order and briefly review the renormalization procedure .
this talk shall provide the philosophical basement as well as serve as an introduction for the material presented at this conference by a. vereshagin and k. semenov - tian - shansky @xcite . .
And you have already written the first three sentences of the full article: in the papers @xcite @xcite we started the systematic study of the special class of effective theories of strong interactions , which we call _ localizable_. roughly speaking , these are theories with the @xmath0-matrix which can be obtained in a _ perturbative way _ in the frame of an _ effective field theory _ that contains auxiliary resonance fields along with the fields of true asymptotic states ( those stable with respect to the strong interaction ) .
our goal is to construct an efficient method for calculating the amplitudes of physical processes .
this means that we need to develop the systematic scheme of perturbative calculations in the framework of infinite component effective field theory ..
Please generate the next two sentences of the article | there are few obstacles that usually prevents the effective theory concept to become a useful computational tool .
the main one is the presence of an infinite number of coupling constants , which requires introducing an infinite number of renormalization prescriptions . |
8,449 | Suppose that you have an abstract for a scientific paper: we present the discovery of a huge ( 19@xmath0 @xmath1 16@xmath0 ) dust ring surrounding a bright ( @xmath2 = 10.60 ) red star .
the dust ring has , at @xmath3pc , a diameter of 4 pc , and a central hole of @xmath41.5 pc across .
part of the shell is also seen as an absorption nebulosity .
the star is classified as a m3iii agb star . among agb stars
its detached shell is of unrivalled size .
detached shells around agb stars are normally interpreted in terms of thermal pulses . however , in this case a significant fraction of the shell may consist of swept - up ism ; the detached appearance can be explained with wind
ism interaction .
we present a model where the agb wind has been stopped by the surrounding ism , and the swept - up shell is now expanding at the sound speed .
the model predicts that the ring will disperse over a few times @xmath5yr , and eventually will leave a large hole in the ism surrounding the agb star or its future planetary nebula . .
And you have already written the first three sentences of the full article: mass loss dominates stellar evolution on the asymptotic giant branch ( agb ) .
the mass loss probably begins on the early agb , or even the first red giant branch @xcite , but culminates during the last 10% of the agb , the thermal - pulsing agb ( tp - agb ) .
observed mass - loss rates range from @xmath6 for semiregulars and miras , up to a few times @xmath7 for oh / ir stars and obscured carbon stars ..
Please generate the next two sentences of the article | typically , the mira phase lasts between @xmath8 and a few times @xmath9 yr ( e.g. @xcite ) . the oh / ir star or the obscured carbon star phase may last @xmath10yr .
because the mass - loss rates increase during the agb evolution , circumstellar shells may be expected to have a centrally - condensed , compact appearance . but |
8,450 | Suppose that you have an abstract for a scientific paper: we report interferometric observations of the semi - regular variable star rs crb , a red giant with strong silicate emission features .
the data were among the first long baseline mid - infrared stellar fringes obtained between the keck telescopes , using parts of the new nulling beam combiner .
the light was dispersed by a low - resolution spectrometer , allowing simultaneous measurement of the source visibility and intensity spectra from 812 @xmath0 m .
the interferometric observations allow a non - ambiguous determination of the dust shell spatial scale and relative flux contribution . using a simple spherically - symmetric model , in which a geometrically thin shell surrounds the stellar photosphere
, we find that @xmath1 30% to @xmath1 70% of the overall mid - infrared flux - depending on the wavelength - originates from 7 - 8 stellar radii .
the derived shell opacity profile shows a broad peak around 11 microns ( @xmath2 0.06 ) , characteristic of mg - rich silicate dust particles . .
And you have already written the first three sentences of the full article: the apparent interferometric sizes of variable red giants vary dramatically - up to a factor of 3 - with wavelength and pulsation phase @xcite + @xcite .
these large variations challenge current hydrodynamical and line opacity models of these stars , indicating that their extended atmospheres are extremely complex .
simultaneous spectroscopic and high angular resolution observations over a wide wavelength range are key to understanding the various phenomena these stars exhibit , including photometric pulsation , high mass - loss rates , dust nucleation , and formation of molecular layers and masers ..
Please generate the next two sentences of the article | high angular resolution thermal infrared observations of bright red giants in _ narrow bandpasses _ ( @xmath3 ) have been available for some time @xcite .
the keck interferometer nuller ( kin ) @xcite and the midi instrument on the vlti @xcite offer much greater spectral coverage , typically over the whole 813 @xmath0 m region , with a sensitivity goal of about 1 jy . the keck interferometer is nearly ideal for the study of such stars . |
8,451 | Suppose that you have an abstract for a scientific paper: we report wide - range optical investigations on transparent conducting networks made from separated ( semiconducting , metallic ) and reference ( mixed ) single - walled carbon nanotubes , complemented by transport measurements . comparing the intrinsic frequency - dependent conductivity of the nanotubes with that of the networks ,
we conclude that higher intrinsic conductivity results in better transport properties , indicating that the properties of the nanotubes are at least as much important as the contacts .
we find that hno@xmath0 doping offers a larger improvement in transparent conductive quality than separation .
spontaneous dedoping occurs in all samples but is most effective in films made of doped metallic tubes , where the sheet conductance returns close to its original value within 24 hours . .
And you have already written the first three sentences of the full article: one of the most promising applications of carbon - based new materials like carbon nanotubes or graphene is the area of transparent conducting layers.@xcite carbon - based materials have many advantages over widely used oxides like indium tin oxide ( ito ) in terms of better flexibility and no toxicity ; however , their basic optical and electrical properties have not reached those of conventional transparent conductors so far .
the field has been broadened recently by the possibility of separating nanotubes by electronic type.@xcite by this method , not only highly enriched semiconducting or metallic networks can be prepared , but also extremely purified mixed samples.@xcite these samples offer a unique opportunity to study the role of intrinsic conductivity vs. intertube contacts in nanotube networks.@xcite intertube connections have been studied previously on junctions built from individual nanotubes@xcite with similar or dissimilar electronic character ( ss , mm or sm , respectively , where m stands for metallic and s for semiconducting tube ) . in macroscopic networks containing predominantly one type of nanotube , and by measuring both the transport and frequency - dependent conductivity , these roles can be even more precisely determined .
impedance studies by garrett et al.@xcite showed that above a characteristic frequency of the order of khz , the values reflect the intrabundle conductance instead of the combined values of bundles and junctions that is measured by the dc method ..
Please generate the next two sentences of the article | thus infrared spectroscopy , which starts at a few thz , clearly yields the intrinsic conductivity of the bundled nanotubes . in this paper
, we report the transparent and conducting properties of separated metallic and semiconducting single - walled nanotube ( swnt ) films and compare them to those of an ultrahigh purity reference sample . |
8,452 | Suppose that you have an abstract for a scientific paper: new observations of variable stars in the globular cluster m3 reveal that the rr lyrae variable v79 is a double - mode ( rrd ) variable with the first overtone mode dominating . in all previous studies , v79 was found to be a fundamental mode ( rrab ) pulsator with an irregular light curve .
this is the first observed mode switch for an rr lyrae variable and it is direct observational evidence for blueward evolution of horizontal branch stars in the oosterhoff type i cluster m3 .
it also demonstrates that there is a connection between the blazhko effect and pulsational mode mixing in rr lyrae variables .
these new observations also show that the strength of the overtone oscillations in the rrd star v68 in m3 may have increased in the last 70 years , thus indicating blueward evolution for v68 as well .
a survey of previously published investigations of rrd stars in oosterhoff type ii systems indicates that there is marginal evidence for an increase in the strength of fundamental mode oscillations in two stars : v30 in m15 and aq leo .
if these increases are confirmed by future observations , it will indicate redward evolution for rrd stars in type ii systems . .
And you have already written the first three sentences of the full article: a standard method for investigating the evolution of horizontal branch stars is to analyze the period changes of rr lyrae variables in globular clusters .
period increases should indicate redward evolution , while decreases indicate blueward evolution , and the rates of change give information about the time scales .
the models of sweigert & renzini ( 1979 ) and lee _ et al ..
Please generate the next two sentences of the article | ( 1990 ) predict that the rr lyrae variables in the oosterhoff type i clusters cross the instability strip during their zahb phase and are therefore expected to have period decreases , which are followed later by increases , when the stars evolve away from the zahb . for the rr lyrae variables in the more metal - poor oosterhoff type ii clusters , the models predict only increasing periods , because these stars cross the instability strip after their zahb phase . since there are a few globular clusters that have been observed over an interval of 100 years , it should be possible to use these observations to test the models .
unfortunately , the observational data do not give definitive results ( cf . |
8,453 | Suppose that you have an abstract for a scientific paper: in some recent studies @xcite , aman _
et al . _ used the ruppeiner scalar as a measure of underlying interactions of reissner - nordstrm black holes , indicating that it is a non - interacting statistical system for which classical thermodynamics could be used at any scale . here , we show that if we use the complete set of thermodynamic variables , a non - flat state space will be produced .
furthermore , the ruppeiner curvature diverges at extremal limits , as it would for other types of black holes . .
And you have already written the first three sentences of the full article: @xmath0 it has been commonly held that black holes are thermodynamic systems @xcite .
black holes obey four laws of black hole mechanics analogous to the four laws of ordinary thermodynamics , posing a bekenstein - hawking entropy and a characteristic hawking temperature related to the surface gravity of event horizon @xcite .
finding the underlying microscopic description of this entropy is one of the most challenging subjects in theoretical physics , but it still remains obscure , best left for future development of quantum theory of gravity @xcite ..
Please generate the next two sentences of the article | thermodynamic fluctuation theory , whose basic goal is to express the time independent probability distribution for the state of a fluctuating system in terms of thermodynamic quantities , is usually attributed to einstein who applied it to the problem of blackbody radiation @xcite .
however , despite a wide range of applications , the classical fluctuation theory fails near critical points and for volumes in the order of the correlation volume or less . in 1979 |
8,454 | Suppose that you have an abstract for a scientific paper: we focus on a recently new intelligent optimization algorithm called discrete state transition algorithm , for solving integer optimization problems .
firstly , we summarize some key elements for discrete state transition algorithm to guide its well development . several intelligent operators are designed for local exploitation and global exploration .
then , a dynamic adjustment strategy risk and restore in probability " is proposed to gain global convergence with high probability .
finally , numerical experiments are carried out to test the effectiveness of the proposed algorithm , and they show that the similar intelligent operators can be applied to ranging from traveling salesman problem , boolean integer programming , to discrete value selection problem , which indicates the robustness and adaptability of the proposed intelligent elements . .
And you have already written the first three sentences of the full article: in this paper , we consider the following unconstrained integer optimization problem @xmath0 where , @xmath1 , @xmath2 , @xmath3 .
+ generally speaking ,
the above optimization problem is np - hard , which can not be solved in polynomial time ( by enumeration , there exist @xmath4 choices ) ..
Please generate the next two sentences of the article | a direct method is to adopt the so called divide - and - conquer " strategy , which separates the optimization problem into several subproblems and then solve these subproblems step by step .
branch and bound ( b&b ) , branch and cut ( b&c ) , and branch and price ( b&p ) belong to this kind ; however , these methods are essentially in exponential time . |
8,455 | Suppose that you have an abstract for a scientific paper: we study the conformal field theory dual of the type iia flux compactification model of dewolfe , giryavets , kachru and taylor , with all moduli stabilized .
we find its central charge and properties of its operator spectrum .
we concentrate on the moduli space of the conformal field theory , which we investigate through domain walls in the type iia string theory .
the moduli space turns out to consist of many different branches .
we use bezout s theorem and bernstein s theorem to enumerate the different branches of the moduli space and estimate their dimension . to on the conformal field theory duals of type iia + @xmath0 flux compactifications + ofer aharony@xmath1 , yaron e. antebi@xmath1 , micha berkooz@xmath1 + _ department of particle physics , + weizmann institute of science , rehovot 76100 , israel _
e - mails : [email protected] , [email protected] , [email protected] .
And you have already written the first three sentences of the full article: flux compactifications of string theory ( for reviews see @xcite ) populate large parts of the string landscape , and may describe our universe .
however , the theoretical basis for the construction of these compactifications is still far from rigorous ( see @xcite for criticism ) , and is based on using low - energy supergravity actions in a regime which is different from the flat - space regime where they are usually derived from string theory .
it would be very interesting if a non - perturbative construction of some flux compactifications could be found , providing further support for their consistency , and perhaps leading to new methods for their analysis ..
Please generate the next two sentences of the article | a promising arena for such a construction is in flux compactifications involving four dimensional anti - de sitter ( ads ) space .
such compactifications are dual , by the ads / cft correspondence @xcite , to three dimensional conformal field theories . |
8,456 | Suppose that you have an abstract for a scientific paper: we report the results of the spectral and timing analysis of observations of the vela pulsar with the _ chandra _ x - ray observatory .
the spectrum shows no statistically significant spectral lines in the observed 0.258.0 kev band .
it consists of two distinct continuum components .
the softer component can be modeled as either a magnetic hydrogen atmosphere spectrum with @xmath0 ev , @xmath1 km , or a standard blackbody with @xmath2 ev , @xmath3 km ( the radii are for a distance of 250 pc ) .
the harder component , modeled as a power - law spectrum , gives photon indices depending on the model adopted for the soft component : @xmath4 for the magnetic atmosphere soft component , and @xmath5 for the blackbody soft component .
timing analysis shows three peaks in the pulse profile , separated by about 0.3 in phase .
energy - resolved timing provides evidence for pulse profile variation with energy . the higher energy ( @xmath6 kev ) profile shows significantly higher pulsed fraction .
# 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 vela pulsar ( b0833 - 45 ) , with a period of 89 millisecond and a characteristic age of 11,000 years , it is the prototype of the young `` vela - like '' pulsars .
the excellent angular resolution of _ chandra _ allows us to separate the pulsar from its synchrotron nebula and study its x - ray properties .
we extracted a total of 16000 counts in the range 0.252.0 kev from two hrc - s / letg observations of 25 ks each ..
Please generate the next two sentences of the article | no deviations of counts in the individual bins from the mean value of neighboring 1020 bins were found with statistical significance higher than 2.7@xmath7 .
this may indicate that there are no elements heavier than h present on the ns surface . |
8,457 | Suppose that you have an abstract for a scientific paper: this paper introduces a new difference scheme to the difference equations for n - body type problems . to find the non - collision periodic solutions and generalized periodic solutions in multi - radial symmetric constraint for the n - body type difference equations , the variational approach and the method of minimizing the lagrangian action
are adopted and the strong force condition is considered correspondingly , which is an efficient method in studying those with singular potentials . and
the difference equation can also be taken into consideration of other periodic solutions with symmetric or choreographic constraint in further studies . .
And you have already written the first three sentences of the full article: the n - body problem is a classical and important problem in celestial mechanics and mathematics .
it consists of determining the orbits of n bodies interacting in accordance with the gravitational law of newton .
that is two bodies attracting each other , the force of attraction being directed along the line joining them , proportional to the product of the masses , and inversely proportional to the square of the distance between them . for given @xmath0 bodies ,.
Please generate the next two sentences of the article | the preceding n - body problem can be described by the following nonlinear system of second order differential equations : @xmath1 where @xmath2 is the mass of @xmath3th body , @xmath4 is the position of @xmath3th body in @xmath5 , @xmath0 is the number of bodies , and @xmath6 is the universal gravitational constant , which is always taken to be 1 for convenience in mathematics .
hence we take @xmath7 in this paper . |
8,458 | Suppose that you have an abstract for a scientific paper: in this paper , we investigate preservation of quantum coherence of a single - qubit interacting with a zero - temperature thermal reservoir throughout the addition of non - interacting qubits in the reservoir .
moreover , we extend this scheme to preserve quantum entanglement between two and three distant qubits which each of them interacting independently with separated reservoirs . at the limit @xmath0 , we obtain analytical expressions for the coherence measure and the concurrence of two and three qubits in terms of the number of additional qubits .
it is observed that , as the number of additional qubits in each reservoir becomes large , the initial coherence and the respective entanglements are completely protected in both markovian and non - markovian regimes .
interestingly , the protection of entanglements occurs even under the individually different behaviors of the reservoirs .
+ + * pacs nos : * + * keywords : * quantum coherence preservation , entanglement preservation , measure of coherence , concurrence , lower bound of concurrence , thermal reservoir , additional qubits , markovian , non - markovian . .
And you have already written the first three sentences of the full article: quantum technology relies on the utilization of resources , like quantum coherence and entanglement , which allow quantum information and computation processing @xmath1
. however , the quantum entanglement is so fragile and undergoes either an asymptotic decay or a sudden death @xmath2 .
this is due to decoherence , whereby the unavoidable interaction between any real quantum system with its surrounding environment alters the quantum system and consequently disentanglement occurs ..
Please generate the next two sentences of the article | therefore , it is very important to investigate the physical systems and physical effects that may lead to effective long - time entanglement preservation .
although there are so - called decoherence - free states whose initial entanglement is invariant over time , however , only a certain kind of entangled state can be decoupled from the influence of the environment in this way @xmath3 . |
8,459 | Suppose that you have an abstract for a scientific paper: the coherent states for a particle on a sphere are introduced .
these states are labelled by points of the classical phase space , that is the position on the sphere and the angular momentum of a particle . as with the coherent states for a particle on a circle discussed in kowalski k _ et al _ 1996 _ j. phys .
a _ * 29 * 4149 , we deal with a deformation of the classical phase space related with quantum fluctuations .
the expectation values of the position and the angular momentum in the coherent states are regarded as the best possible approximation of the classical phase space .
the correctness of the introduced coherent states is illustrated by an example of the rotator . 8.8 in = .5 cm = .5 cm .
And you have already written the first three sentences of the full article: it has become a clich to say that coherent states abound in quantum physics @xcite .
moreover , it turns out that they can also be applied in the theory of quantum deformations @xcite and even in the theory of classical dynamical systems @xcite . in spite of the fact that the problem of the quantization of a particle motion on a sphere is at least seventy years old
, there still remains an open question concerning the coherent states for a particle on a sphere ..
Please generate the next two sentences of the article | indeed , the celebrated spin coherent states introduced by radcliffe @xcite and perelomov @xcite are labelled by points of a sphere , i.e. , the elements of the configuration space .
on the other hand , it seems that as with the standard coherent states , the coherent states for a particle on a sphere should be marked with points of the phase space rather than the configuration space . |
8,460 | Suppose that you have an abstract for a scientific paper: in the framework of three - dimensional born - infeld electrodynamics , we pursue an investigation of the consequences of the space - time dimensionality on the existence of magnetostatic fields generated by electric charges at rest in an inertial frame , which are present in its four - dimensional version .
our analysis reveals interesting features of the model .
in fact , a magnetostatic field associated with an electric charge at rest does not appear in this case .
interestingly , the addition of the topological term ( chern - simons ) to born - infeld electrodynamics yields the appearance of the magnetostatic field .
we also contemplate the fields associated to the would - be - magnetic monopole in three dimensions . .
And you have already written the first three sentences of the full article: as well - known , nonlinear born - infeld electrodynamics has become , over the past years , a focus of intense activity after its connection with brane physics has been elucidated .
specifically , the low - energy dynamics of d - branes can be described by a nonlinear born - infeld - type action @xcite .
we further recall that born and infeld @xcite suggested to modify maxwell electrodynamics to get rid of infinities in the theory ..
Please generate the next two sentences of the article | also , it is important to mention that , in addition to the string interest , the born - infeld theory has also attracted attention from different viewpoints .
for example , in connection with noncommutative field theories @xcite , also in magnetic monopoles studies @xcite , and possible experimental determination of the parameter that measures the nonlinearity of the theory @xcite . |
8,461 | Suppose that you have an abstract for a scientific paper: in the random - interaction ensembles , three proportional correlations between quadrupole moments of the first two @xmath0 states robustly emerge , including @xmath1 correlations consistently with realistic nuclear survey , and the @xmath2 correlation , which is only observed in the @xmath3-boson space .
these correlations can be microscopically characterized by the rotational su(3 ) symmetry and quadrupole vibrational u(5 ) limit , respectively , according to the elliott model and the @xmath3-boson mean - field theory .
the anharmonic vibration may be another phenomenological interpretation for the @xmath4 correlation , whose spectral evidence , however , is insufficient . utf8 .
And you have already written the first three sentences of the full article: finite many - body systems ( e.g. , nuclei , small metallic grains , metallic clusters ) robustly maintain similar regularities , despite their different binding interactions .
for example , they all present the odd - even staggering on their binding energies , which are , however , attributed to various mechanisms @xcite . particularly in nuclear systems , the nucleon - nucleon interactions numerically exhibit a random " pattern with no trace of symmetry groups , whereas nuclear spectra follow some robust dynamical features : the nuclear spectral fluctuation is universally observed @xcite ; low - lying spectra of even - even nuclei are orderly and systematically characterized by seniority , vibrational and rotational structures @xcite , beyond @xmath5 ground states without exception . to demonstrate the insensitivity of these robust regularities to the interaction details , and to reveal its underlying origin , random interactions are employed to simulate ( or even introduce ) the variety and chaos into a finite many - body system .
thus , the predominant behaviors in a random - interaction ensemble correspond to dynamical features in a realistic system ..
Please generate the next two sentences of the article | many efforts have been devoted along this direction @xcite .
for instance , similarly to realistic even - even nuclei , the predominance of the @xmath6 ground states @xcite and collective band structures @xcite have been observed in random - interaction ensembles . however , there are only few attempts to study the robustness of nuclear quadrupole collectivity against the random interaction . |
8,462 | Suppose that you have an abstract for a scientific paper: we present a qcd sum rule analysis for the newly observed resonance @xmath0 by assuming it as a @xmath1 molecular state .
technically , contributions of operators up to dimension @xmath2 are included in the operator product expansion ( ope ) .
we find that it is difficult to find the conventional ope convergence in this work . by trying releasing the rigid ope convergence criterion
, one could find that the ope convergence is still under control in the present work and the numerical result for @xmath1 state is @xmath3 , which is in agreement with the experimental data of @xmath0 . in view of
that the conventional ope convergence is not obtained here , thus only weak conclusions can be drawn regarding the explanation of @xmath0 in terms of a @xmath1 molecular state . as a byproduct , the mass for the bottom counterpart @xmath4 state is predicted to be @xmath5 . .
And you have already written the first three sentences of the full article: very recently , babar collaboration reported the measurement of the baryonic @xmath6 decay @xmath7 and observed a new structure in the @xmath8 invariant mass spectrum at @xmath9 @xcite . for simplicity , one could name the new structure as @xmath0 .
soon after the experimental observation , he
_ et al . _ have suggested that @xmath0 could be a @xmath1 molecular state from an effective lagrangian calculation @xcite . theoretically , the molecular concept is well and truly not a new topic but with a history ..
Please generate the next two sentences of the article | it was put forward nearly 40 years ago in ref .
@xcite and was predicted that molecular states have a rich spectroscopy in ref . |
8,463 | Suppose that you have an abstract for a scientific paper: a new research project on spectral analysis that aims to characterize the vertical stratification of element abundances in stellar atmospheres of chemically peculiar ( cp ) stars is discussed in detail .
some results on detection of vertical abundance stratification in several slowly rotating main sequence cp stars are presented and considered as an indicator of the effectiveness of the atomic diffusion mechanism responsible for the observed peculiarities of chemical abundances .
this study is carried out in the frame of project veselka ( vertical stratification of elements abundance ) for which 34 slowly rotating cp stars have been observed with the espadons spectropolarimeter at cfht . + * key words : * diffusion , line : profiles , stars : abundances , atmospheres , chemically peculiar , magnetic field , rotation @xmath0dpartement de physique et dastronomie , universit de moncton , moncton , n .- b . , canada e1a 3e9 + [email protected] + [email protected] .
And you have already written the first three sentences of the full article: at certain stages of stellar evolution , some stars show peculiarity of spectral lines in their spectra that argues in favour of an enhanced or depleted abundance of several chemical species in their stellar atmospheres with respect to the solar abundance . abnormally strong lines of silicon in @xmath1 cvn were first reported by antonia maury @xcite , while the strong lines of ionised silicon and ionised strontium were found by annie cannon @xcite in some bright southern stars in the process of determining their spectral class .
the first systematic study and classification of stars of spectral classes b - f with abnormally strong lines of various chemical species was performed by morgan @xcite . to explain the mystery of the observed abnormally strong lines , shapley @xcite suggested the possibility of abundance abnormalities in the atmospheres of these stars .
several decades later , this idea was confirmed by the results of a differential coarse analysis using the curves of growth @xcite ..
Please generate the next two sentences of the article | it should be noted , that the observed peculiar abundance of chemical species is only related to the stellar atmosphere and does not reflect the chemical composition of the entire star .
we turn our attention to two types of stars with abundance anomalies : blue horizontal - branch ( bhb ) stars that burn helium in their core and hydrogen in a shell @xcite , and main sequence stars that burn hydrogen in their core . |
8,464 | Suppose that you have an abstract for a scientific paper: we present a systematic and comprehensive study of finite - size effects in diffusion quantum monte carlo calculations of metals .
several previously introduced schemes for correcting finite - size errors are compared for accuracy and efficiency and practical improvements are introduced . in particular , we test a simple but efficient method of finite - size correction based on an accurate combination of twist averaging and density functional theory .
our diffusion quantum monte carlo results for lithium and aluminum , as examples of metallic systems , demonstrate excellent agreement between all of the approaches considered . .
And you have already written the first three sentences of the full article: density functional theory ( dft ) has dominated atomic - scale materials modeling for the past three decades and will continue to be extremely important . however , there are plenty of problems where the accuracy of dft falls short of requirements .
there are clear reasons to expect dft to struggle in strongly - correlated solids , but these are not the only systems for which dft is insufficient .
take , for example , the problem of distinguishing between molecular crystal phases and competing low - energy polymorphs ..
Please generate the next two sentences of the article | even in relatively simple molecular solids such as crystalline benzene and its polymorphs under pressure , the energy differences of interest are less than a few kj / mol .
the most successful calculations based on dft are only reliable to @xmath010 kj / mol,@xcite and it has recently been shown that the use of _ ab initio _ many - electron wavefunction methods , such as quantum monte carlo ( qmc ) , is essential to tackle this problem successfully.@xcite unlike dft , many - electron wavefunction methods can , in principle , be improved systematically until the required convergence is obtained . |
8,465 | Suppose that you have an abstract for a scientific paper: optical observations of the companions of pulsars can help determine the properties of the binaries , as well as those of their components , and give clues to the preceding evolution . in this review ,
we first describe the different classes of binary pulsars , and present a table with a summary what is known about their optical counterparts .
next , we focus on the class of pulsars that have low - mass , helium - core white dwarf companions .
we discuss attempts to determine the masses of both components using optical spectroscopy , and compare the pulsar spin - down ages with cooling ages of the white dwarfs .
we confirm that for a given age , the lowest - mass white dwarfs are much hotter than the more massive ones , consistent with recent evolutionary models , although with one glaring exception .
we discuss the case of psr b0820 + 02 , where the cooling age indicates a braking index less than 3 , and conclude by describing how cooling ages can be used to test formation scenarios for psr j1911@xmath05958a , a pulsar binary in the outskirts of ngc 6752 . .
And you have already written the first three sentences of the full article: in table [ tab : optical ] , we list all pulsars in binaries outside of globular clusters .
one sees that their properties vary widely , but one can identify different types on the basis of the spin and orbital properties . for instance , systems separate in clusters by inferred companion mass and orbital period , as can be seen in fig .
[ fig : porbvsmass ] ..
Please generate the next two sentences of the article | below , we briefly describe the different groups and their evolutionary histories ( for reviews , see phinney & kulkarni 1994 ; stairs 2004 ) .
pulsars with massive stellar companions , which formed in binaries in which one star went supernova . |
8,466 | Suppose that you have an abstract for a scientific paper: solutions of partial differential equations ( pdes ) on manifolds have provided important applications in different fields in science and engineering .
existing methods are majorly based on discretization of manifolds as implicit functions , triangle meshes , or point clouds , where the manifold structure is approximated by either zero level set of an implicit function or a set of points . in many applications ,
manifolds might be only provided as an inter - point distance matrix with possible missing values .
this paper discusses a framework to discretize pdes on manifolds represented as incomplete distance information . without conducting a time - consuming global coordinates reconstruction
, we propose a more efficient strategy by discretizing differential operators only based on point - wisely local reconstruction .
our local reconstruction model is based on the recent advances of low - rank matrix completion theory , where only a very small random portion of distance information is required .
this method enables us to conduct analyses of incomplete distance data using solutions of special designed pdes such as the laplace - beltrami ( lb ) eigen - system . as an application , we demonstrate a new way of manifold reconstruction from an incomplete distance by stitching patches using the spectrum of the lb operator .
intensive numerical experiments demonstrate the effectiveness of the proposed methods . .
And you have already written the first three sentences of the full article: with the rapid development of advanced data acquisition technology , processing and analyzing data sampled on 3d shapes or even higher dimensional geometric objects becomes ubiquitous tasks such as those used in a 3d camera , medical imaging , protein structuring , social network analysis etc .
partial differential equation ( pde ) and variational pde based methods have made great success to handle problems in signal and image processing which can be viewed as data on euclidean domains .
it is natural to consider pde based methods to analyze and process signals on a general manifold and to understand geometric structures hidden in the data ..
Please generate the next two sentences of the article | besides the classical implicit method @xcite , finite difference methods @xcite and finite element methods @xcite for solving differential equations on surfaces in @xmath0 , there has been increasing interests of solving pdes on general @xmath1-dimensional manifold in @xmath2 and their applications to data analysis .
for instance , a diffusion geometry framework is developed to investigate the geometric structure of data based on solving laplace - beltrami ( lb ) eigenproblem using integral kernel methods @xcite . |
8,467 | Suppose that you have an abstract for a scientific paper: we have obtained deep , multi - band imaging observations around three of the most distant known quasars at redshifts @xmath0 .
standard accretion theory predicts that the supermassive black holes present in these quasars were formed at a very early epoch .
if a correlation between black hole mass and dark matter halo mass is present at these early times , then these rare supermassive black holes will be located inside the most massive dark matter halos .
these are therefore ideal locations to search for the first clusters of galaxies .
we use the lyman - break technique to identify star - forming galaxies at high redshifts .
our observations show no overdensity of star - forming galaxies in the fields of these quasars .
the lack of ( dust - free ) luminous starburst companions indicates that the quasars may be the only massive galaxies in their vicinity undergoing a period of intense activity . .
And you have already written the first three sentences of the full article: the existence of inactive supermassive black holes in the nuclei of massive nearby galaxies ( magorrian et al .
1998 ) is a sure sign that most galaxies underwent substantial active phases .
furthermore , the correlation between the amount of material accreted ( black hole mass ) and the galaxy mass indicates important links between galaxy formation and agn activity ..
Please generate the next two sentences of the article | one implication is that the most massive black holes live in the most massive galaxies which reside in the most massive dark matter halos .
the @xmath0 quasars being discovered in the sloan digital sky survey ( see fan , this volume ) have exceptionally high luminosities ( @xmath1 ) . |
8,468 | Suppose that you have an abstract for a scientific paper: ferromagnetic resonance ( fmr ) measurements are performed as a function of temperature on nickel nanowires with different diameters ( 15 nm , 50 nm , 80 nm and 100 nm ) from room temperature down to liquid helium ( 4.2 k ) .
the resonance field @xmath0 measured as a function of field angle and temperature yields interesting information about the size and temperature variation of various anisotropy effects . with diameter increase from 15 nm to 100
nm we observe a transition at 50 nm in easy axis orientation from perpendicular to parallel to the nanowire array axis .
the temperature variation of @xmath0 is analyzed and explained theoretically with presence of strong magneto - elastic effects in small ( 15 nm ) and large diameter ( 100 nm ) nanowire arrays . .
And you have already written the first three sentences of the full article: ferromagnetic nanowires possess interesting properties that might be exploited in spintronic devices and more specifically in non - volatile memory ( mram ) and magnetic logic devices @xcite .
the mermin - wagner @xcite theorem forbids ( heisenberg - type ) magnetism in systems of dimension ( @xmath1 ) with short - range interactions .
hence , ferromagnetic nanowires being a quasi - one dimensional system displaying magnetic properties represent an interesting system from the fundamental point of view ..
Please generate the next two sentences of the article | in addition to their interest in fundamental magnetism , they have many applications in microwave devices such as circulators , superconducting single - photon ghz detectors and counters @xcite , mass information storage ( perpendicular recording ) as read - write recording heads , magneto - electronics ( wire bending angle dependent gmr ) as well as in quantum computing and telecommunication .
they are simpler than nanotubes since their physical properties do not depend on chirality and they can be grown with a variety of methods : molecular beam epitaxy , electrochemical methods ( template synthesis , anodic alumina filters ) , chemical solution techniques ( self - assembly , sol - gel , emulsions ... ) etc ... ordered nanowire arrays may be of paramount importance in areas such as extremely high - density information recording of patterned media such as the quantum magnetic disk @xcite and in novel high - frequency communication or signal - processing devices based on the exploitation of spin - waves ( magnonic devices ) @xcite to transfer and process information of spin - currents with no disspative joule effect . in this work , |
8,469 | Suppose that you have an abstract for a scientific paper: a certain vector - tensor ( vt ) theory of gravitation was tested in previous papers . in the background universe
, the vector field of the theory has a certain energy density , which is appropriate to play the role of vacuum energy ( cosmological constant ) .
moreover , this background and its perturbations may explain the temperature angular power spectrum of the cosmic microwave background ( cmb ) obtained with wmap ( wilkinson map anisotropy probe ) , and other observations , as e.g. , the ia supernova luminosities . the parametrized post - newtonian limit of the vt theory has been proved to be identical to that of general relativity ( gr ) , and there are no quantum ghosts and classical instabilities . here , the stationary spherically symmetric solution , in the absence of any matter content , is derived and studied .
the metric of this solution is formally identical to that of the reissner - nordstrm - de sitter solution of gr , but the role of the electrical charge is played by a certain quantity @xmath0 depending on both the vector field and the parameters of the vt theory . the black hole and cosmological horizons are discussed .
the radius of the vt black hole horizon deviates with respect to that of the kottler - schwarzschild - de sitter radius .
realistic relative deviations depend on @xmath0 and reach maximum values close to 30 per cent . for large enough @xmath0 values
, there is no any black hole horizon , but only a cosmological horizon .
the radius of this last horizon is almost independent of the mass source , the vector field components , and the vt parameters .
it essentially depends on the cosmological constant value , which has been fixed by using cosmological observational data ( cmb anisotropy , galaxy correlations and so on ) . .
And you have already written the first three sentences of the full article: recently , several vector - tensor ( vt ) theories involving a vector field , @xmath1 , and the metric tensor @xmath2 have been applied to cosmology @xcite ; in these theories , the background energy density , @xmath3 , of the vector field @xmath1 plays the role of the dark energy ( hereafter the subscript @xmath4 stands for background ) ; for example , in @xcite , where the theory of gravitation considered in this paper was proposed , the equation of state is @xmath5 , where @xmath6 is the pressure due to the field @xmath1 and @xmath7 ; hence , the constant energy @xmath8 plays the role of vacuum energy .
however , in the theory studied in @xcite , which might be appropriate to explain the anomalies observed in the angular spectrum of the cosmic microwave background ( cmb ) for small @xmath9 multipoles , the equation of state is @xmath10 , where @xmath11 is negative for any value of the scale factor @xmath12 ; hence , in this theory , we have a sort of dynamical dark energy different from that associated to the cosmological constant ( vacuum energy ) . here
, our attention is focused on the theory proposed by @xcite , which was applied to cosmology in @xcite and @xcite . in this last reference ,.
Please generate the next two sentences of the article | the vt theory under consideration was proved to be viable in the sense that : ( i ) its post - newtonian parametrized limit is identical to that of general relativity ( gr ) , and ( ii ) the theory may simultaneously explain the seven year wmap data about the cmb temperature anisotropy and the measurements of supernova ia luminosities . conclusion ( ii )
was obtained by using the well - known bardeen formalism @xcite to write the evolution equations of the scalar linear perturbations in vt theory , and also to find the initial conditions at high redshift necessary to solve these equations [ see @xcite ] . by using these elements , a modified version of the code cosmomc @xcite based on statistical techniques as the markov chains was designed to fit the vt predictions with the observational data mentioned above . a model involving seven free cosmological parameters |
8,470 | Suppose that you have an abstract for a scientific paper: a deep all - sky imaging hard x - ray survey and wide - field monitor is needed to extend soft ( rosat ) and medium ( abrixas2 ) x - ray surveys into the 10 - 100 kev band ( and beyond ) at comparable sensitivity ( 0.05 mcrab ) .
this would enable discovery and study of 3000 obscured agn , which probably dominate the hard x - ray background ; detailed study of spectra and variability of accreting black holes and a census of bhs in the galaxy ; gamma - ray bursts and associated massive star formation ( popiii ) at very high redshift and soft gamma - ray repeaters throughout the local group ; and a full galactic survey for obscured supernova remnants .
the energetic x - ray imaging survey telescope ( exist ) is a proposed array of 8 1m@xmath0 coded aperture telescopes fixed on the international space station ( iss ) with 60x40deg field of view which images the full sky each 90 min orbit .
exist has been included in the most recent nasa strategic plan as a candidate mission for the next decade .
an overview of the science goals and mission concept is presented . /cm2secergs
@xmath1 s@xmath2 2ergs @xmath1 2cm@xmath0 cm2sec @xmath1 s@xmath2 60x40deg160@xmath4 40 0x6deg20@xmath4 6 44@xmath5ti .
And you have already written the first three sentences of the full article: the full sky has not been surveyed in space ( imaging ) and time ( variability ) at hard x - ray energies . yet
the hard x - ray ( hx ) band , defined here as 10 - 600 kev , is key to some of the most fundamental phenomena and objects in astrophysics : the nature and ubiquity of active galactic nuclei ( agn ) , most of which are likely to be heavily obscured ; the nature and number of black holes ; the central engines in gamma - ray bursts ( grbs ) and the study of grbs as probes of massive star formation in the early universe ; and the temporal measurement of extremes : from khz qpos to sgrs for neutron stars , and microquasars to blazars for black holes .
a concept study was conducted for the energetic x - ray imaging survey telescope ( exist ) as one of the new mission concepts selected in 1994 ( grindlay et al 1995 ) ..
Please generate the next two sentences of the article | however the rapid pace of discovery in the hx domain in the past 2 years , coupled with the promise of a likely 2 - 10 kev imaging sky survey abrixas2 ( see http://www.aip.de/cgi-bin/w3-msql/groups/xray/abrixas/index.html ) in c.2002 - 2004 and the recent selection of swift ( see http://swift.gsfc.nasa.gov/ ) which will include a 10 - 100 kev partial sky survey ( to 1 mcrab ) in c.2003 - 2006 , have prompted a much more ambitious plan .
a dedicated hx survey mission is needed with full sky coverage each orbit and 0.05 mcrab all - sky sensitivity in the 10 - 100 kev band ( comparable to abrixas2 ) and extending into the 100 - 600 kev band with 0.5 mcrab sensitivity . |
8,471 | Suppose that you have an abstract for a scientific paper: in this paper we study a system of @xmath0 coupled quantum oscillators interacting with each other directly with varying coupling strengths and indirectly through linear couplings to a scalar massless quantum field as its environment .
the influence of the quantum field on the system is calculated with the use of the influence functional formalism .
we take the direct route of seeking solutions to the evolutionary operator of the reduced density matrix for the derivation of the correlation functions .
they are then used to construct the covariance matrix which we use to perform an analysis of the structure of quantum entanglement in the open system at a stationary state . to see the physical features more explicitly we specialize to a system of three quantum coupled oscillators placed at the vertices of a equilateral triangle and allowed to have disparate pairwise couplings .
we analyze the entanglement between one oscillator and the other two with equal ( symmetric ) and unequal ( asymmetric ) coupling strengths . as an illustration we use the results for these two different configurations to address two representative issues in macroscopic quantum phenomena .
we also mention possible extensions of our work and applications of our analysis and results to issues in some current areas of research in quantum thermodynamics and mesoscopic quantum systems . quantum entanglement , open quantum systems , macroscopic quantum phenomena , influence functional formalism , quantum field theory , quantum brownian motion , non - markovian dynamics .
And you have already written the first three sentences of the full article: in our first paper on this subject matter @xcite we studied a model of @xmath0 quantum oscillators ( qo ) located at different fixed positions in space , which do not interact with each other directly but only through weak couplings to a common scalar massless quantum field .
after coarse - graining the quantum field we derived the late - time covariance matrix of the open system of the @xmath0 oscillators with field - induced coupling and analyzed the structure of their quantum entanglement behavior for the case of @xmath1 .
we show that in the weak coupling limit the correlations adopt a simple pairwise structure , in that the correlation between any two qo is ignorant of the presence of the other qo ..
Please generate the next two sentences of the article | the effects of field - induced interaction on quantum entanglement between two harmonic oscillators have been studied earlier in @xcite .
one interesting new feature shown there is the distance dependence of quantum entanglement , since the coupling is mediated by a quantum field whose influence varies with time and space . |
8,472 | Suppose that you have an abstract for a scientific paper: the derivation of the feynman rules for lattice perturbation theory from actions and operators is complicated , especially for highly improved actions such as hisq .
this task is , however , both important and particularly suitable for automation .
we describe a suite of software to generate and evaluate feynman rules for a wide range of lattice field theories with gluons and ( relativistic and/or heavy ) quarks . our programs are capable of dealing with actions as complicated as ( m)nrqcd and hisq .
automated differentiation methods are used to calculate also the derivatives of feynman diagrams .
quantum chromodynamics , qcd , lattice qcd , perturbation theory 11.15.ha , 12.38.gc 81 - 04 , 81t13 , 81t15 , 81t18 , 81t25 , 81v05 , 65s05 ,
41a58 * program summary * _ manuscript title : _ automated generation of lattice qcd feynman rules + _ authors : _ a. hart , g.m .
von hippel , r.r .
horgan , e.h .
mller .
+ _ program title : _ hippy , hpsrc + _ journal reference : _
+ _ catalogue identifier : _ + _ licensing provisions : _ gplv2 ( see note in sec . [ sec_licence ] . )
+ _ programming languages : _ python , fortran95 + _ ram : _ problem specific , typically less than 1 gb for either code . + _ keywords : _ quantum chromodynamics , qcd , lattice qcd , perturbation theory + _ pacs : _ 11.15.ha ; 12.38.gc + _ classification : _ 4.4 feynman diagrams ; 11.5 quantum chromodynamics , lattice gauge theory + _ nature of problem : _
+ derivation and use of perturbative feynman rules for complicated lattice qcd actions .
+ _ solution method : _ + an automated expansion method implemented in python ( hippy ) and code to use expansions to generate feynman rules in fortran95 ( hpsrc ) .
+ _ restrictions : _ + no general restrictions .
specific restrictions are discussed in the text . + _ running time : _
+ very problem specific , depending on the complexity of the feynman rules and the number of integration points . typically between a few minutes and several weeks . .
And you have already written the first three sentences of the full article: non abelian gauge theories are the most important ingredient in our present understanding of elementary particles and their interactions .
in particular , quantum chromodynamics ( qcd ) is now universally believed to be the correct theory of the strong interactions . however , while perturbation theory has been used successfully in describing the scattering of particles by partons , the perturbative series does not converge at hadronic energy scales .
moreover , the phenomena of confinement and the hadronic spectrum are fundamentally beyond the reach of perturbation theory . therefore , non - perturbative monte carlo simulations of lattice - regularised qcd are crucial in order to obtain a full description and understanding of qcd phenomena ..
Please generate the next two sentences of the article | the lattice regularisation with a lattice spacing @xmath0 does , however , introduce a sharp momentum cutoff at the momentum scale @xmath1 . connecting lattice measurements to their continuum counterparts therefore requires renormalisation factors accounting for the excluded high - frequency modes .
in particular , renormalisation is needed for qcd matrix elements , and for fixing the bare quark masses to be used in the lattice lagrangian . |
8,473 | Suppose that you have an abstract for a scientific paper: long - duration @xmath0-ray bursts ( grbs ) at @xmath1 are in most cases found to be accompanied by bright , broad - lined type ic supernovae ( sne ic - bl ) .
the highest - energy grbs are mostly located at higher redshifts , where the associated sne are hard to detect observationally . here
we present early and late observations of the optical counterpart of the very energetic grb 130427a . despite its moderate redshift @xmath2 , grb 130427a
is at the high end of the grb energy distribution , with an isotropic - equivalent energy release of @xmath3 erg , more than an order of magnitude more energetic than other grbs with spectroscopically confirmed sne . in our dense photometric monitoring ,
we detect excess flux in the host - subtracted @xmath4-band light curve , consistent with that expected from an emerging sn , @xmath5 mag fainter than the prototypical sn 1998bw .
a spectrum obtained around the time of the sn peak ( 16.7 days after the grb ) reveals broad undulations typical of sne ic - bl , confirming the presence of a sn , designated sn 2013cq .
the spectral shape and early peak time are similar to those of the high expansion velocity sn 2010bh associated with grb 100316d .
our findings demonstrate that high - energy long - duration grbs , commonly detected at high redshift , can also be associated with sne ic - bl , pointing to a common progenitor mechanism . .
And you have already written the first three sentences of the full article: the standard paradigm for long - duration gamma - ray bursts ( grbs ) involves a broad - lined type ic supernova ( sn ic - bl ) with @xmath6 mag @xcite , such as those predicted by the collapsar model @xcite .
this is based on spectroscopic evidence in sne from low - luminosity grbs @xcite , such as sn 1998bw accompanying grb 980425 @xcite , as well as relatively - higher - luminosity grbs , such as sn 2003dh accompanying grb 030329 @xcite .
interestingly , for the two low - redshift cases of grb 060505 and grb 060614 no associated sn was found to deep limits @xcite , but since then no similar events have been reported ..
Please generate the next two sentences of the article | grb 130427a @xcite is remarkable as it is both extremely energetic and located at a moderately low redshift of @xmath2 ( @xcite and this work ) . using the spectral parameters for the prompt emission given by @xcite
, we derive an isotropic @xmath0-ray energycdm cosmology with @xmath7 km s@xmath8 mpc@xmath8 , @xmath9 , and @xmath10 @xcite . |
8,474 | Suppose that you have an abstract for a scientific paper: we provide an exhaustive analysis of the integrated sach wolfe effect ( isw ) in the context of coupled dark energy cosmologies where a component of massive neutrinos is also present .
we focus on the effects of both the coupling between dark matter and dark energy and of the neutrino mass on the cross - correlation between galaxy / quasar distributions and isw effect .
we provide a simple expression to appropriately rescale the galaxy bias when comparing different cosmologies .
theoretical predictions of the cross
correlation function are then compared with observational data .
we find that , while it is not possible to distinguish among the models at low redshifts , discrepancies between coupled models and @xmath0cdm increase with @xmath1 . in spite of this
, current data alone seems not able to distinguish between coupled models and @xmath0cdm .
however , we show that upcoming galaxy surveys will permit tomographic analysis which allow to better discriminate among the models .
we discuss the effects on cross - correlation measurements of ignoring galaxy bias evolution , @xmath2 , and magnification bias correction and provide fitting formulae for @xmath2 for the cosmologies considered .
we compare three different tomographic schemes and investigate how the expected signal to noise ratio , @xmath3 , of the isw
lss cross correlation changes when increasing the number of tomographic bins .
the dependence of @xmath3 on the area of the survey and the survey shot noise is also discussed . .
And you have already written the first three sentences of the full article: several observations made over the recent years , related to a large extension to large scale structures ( lss ) and anisotropies of the cosmic microwave background ( cmb ) as well as the magnitude redshift relation for type ia supernovae have given us a convincing picture of the energy and matter density in the universe @xcite .
baryonic matter accounts for no more than 30@xmath4 of the mass in galaxy clusters while the existence of a large clustered component of dark matter ( dm ) seems now firmly established , although its nature is still unknown . however , they contribute to the total energy density of the universe with only a few percent and about 25@xmath4 respectively .
no more than another few percent could be accounted for by massive neutrinos , but only in the most favorable , but unlikely case . according to @xcite.
Please generate the next two sentences of the article | ( see also @xcite ) the total mass of neutrinos can not exceed the limit of 1.43 @xmath5 ( see , however , @xcite for a recent analysis on neutrino mass limits in coupled dark energy models ) . a very small part @xmath6 of the total energy density is due to massless neutrinos and cmb radiation .
the model suggested by observations is only viable if the remaining 75@xmath4 is ascribed to the so called dark energy ( de ) responsible for the present day cosmic acceleration . |
8,475 | Suppose that you have an abstract for a scientific paper: we have measured the angular and spatial clustering of 671 @xmath0 , @xmath1 extremely red objects ( eros ) from a @xmath2 sub - region of the noao deep wide - field survey ( ndwfs ) .
our study covers nearly 5 times the area and has twice the sample size of any previous ero clustering study .
the wide field of view and @xmath3 passbands of the ndwfs allow us to place improved constraints on the clustering of @xmath4 eros .
we find the angular clustering of eros is slightly weaker than in previous measurements , and @xmath5 for @xmath0 eros .
we find no significant correlation of ero spatial clustering with redshift , apparent color or absolute magnitude , although given the uncertainties , such correlations remain plausible .
we find the spatial clustering of @xmath0 , @xmath1 eros is well approximated by a power - law , with @xmath6 in comoving coordinates .
this is comparable to the clustering of @xmath7 early - type galaxies at @xmath8 , and is consistent with the brightest eros being the progenitors of the most massive ellipticals .
there is evidence of the angular clustering of eros decreasing with increasing apparent magnitude , when ndwfs measurements of ero clustering are combined with those from the literature .
unless the redshift distribution of @xmath9 eros is very broad , the spatial clustering of eros decreases from @xmath6 for @xmath0 to @xmath10 for @xmath9 eros . .
And you have already written the first three sentences of the full article: the evolution of galaxy clustering is a prediction of hierarchical models of galaxy and structure formation ( e.g. , * ? ? ?
* ; * ? ? ?
* ; * ? ? ?.
Please generate the next two sentences of the article | hierarchical models for a concordance cosmology , @xmath11 , @xmath12 , and comoving coordinates . ] predict little or no evolution of the clustering of @xmath13 red galaxies at @xmath14 .
precise measurements of galaxy clustering at @xmath4 can therefore test the predictions of these models . |
8,476 | Suppose that you have an abstract for a scientific paper: we present the results of the radio observations of the afterglow of grb 030329 with the nobeyama 45-m telescope .
the observations were made at 23.5 ghz , 43 ghz , and 90 ghz .
the light curves show steep decline after constant phase .
the start time of the decline depends on frequency .
namely , the decline started earlier at higher frequency .
the spectrum has a peak at mm wavelength range . the peak frequency and
the peak flux decreased with time .
these results are consistent with the expectation from the fireball model . .
And you have already written the first three sentences of the full article: in the fireball model , afterglows of gamma - ray bursts are described by synchrotron radiation from a relativistic blast wave ( piran 1999 ) .
radio observations of the afterglow of gamma - ray bursts at millimeter wavelengths are very important , since they can trace time evolution of the synchrotron spectrum directly and make it possible to derive physical parameters of gamma - ray bursts .
therefore , many observations of radio afterglows of gamma - ray bursts have been made so far ( frail et al . 2003 ) ..
Please generate the next two sentences of the article | grb 030329 is one of the closest events .
its redshift is @xmath0 . |
8,477 | Suppose that you have an abstract for a scientific paper: joint sparsity offers powerful structural cues for feature selection , especially for variables that are expected to demonstrate a `` grouped '' behavior .
such behavior is commonly modeled via group - lasso , multitask lasso , and related methods where feature selection is effected via mixed - norms . several mixed - norm based sparse models have received substantial attention , and for some cases efficient algorithms are also available .
surprisingly , several _ constrained _ sparse models seem to be lacking scalable algorithms .
we address this deficiency by presenting batch and online ( stochastic - gradient ) optimization methods , both of which rely on efficient projections onto mixed - norm balls .
we illustrate our methods by applying them to the multitask lasso .
we conclude by mentioning some open problems . _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ * keywords : * mixed - norm , group sparsity , fast projection , multitask learning , matrix norms , stochastic gradient _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ .
And you have already written the first three sentences of the full article: sparsity encodes key structural information about data and permits estimating unknown , high - dimensional vectors robustly .
no wonder , sparsity has been intensively studied in signal processing , machine learning , and statistics , and widely applied to many tasks therein . but the associated literature has grown too large to be summarized here ; so we refer the reader to @xcite as starting points .
sparsity constrained problems are often cast as instances of the following high - level optimization problem @xmath0 where @xmath1 is a differentiable loss - function , @xmath2 is a convex ( nonsmooth ) regularizer , and @xmath3 is a scalar ..
Please generate the next two sentences of the article | alternatively , one may prefer the constrained formulation @xmath4 both formulations and continue to be actively researched , the former perhaps more than the latter .
we focus on the latter , primarily because it often admits simple but effective first - order optimization algorithms |
8,478 | Suppose that you have an abstract for a scientific paper: new observations of jupiter s decametric radio emissions have been made with the long wavelength array station 1 ( lwa1 ) which is capable of making high quality observations as low as 11 mhz .
full stokes parameters were determined for bandwidths of 16 mhz . here
we present the first lwa1 results for the study of six io - related events at temporal resolutions as fine as 0.25 ms .
lwa1 data show excellent spectral detail in jovian dam such as simultaneous left hand circular ( lhc ) and right hand circular ( rhc ) polarized io - related arcs and source envelopes , modulation lane features , s - bursts structures , narrow band n - events , and interactions between s - bursts and n - events .
the sensitivity of the lwa1 combined with the low radio frequency interference environment allow us to trace the start of the lhc io - c source region to much earlier than typically found in the literature .
we find the io - c starts as early as = 230@xmath0 at frequencies near 11 mhz .
this early start of the io - c emission may be valuable for refining models of the emission mechanism .
we also detect modulation lane structures that appear continuous across lhc and rhc emissions , suggesting that both polarizations may originate from the same hemisphere of jupiter .
we present a study of rare s - bursts detected during an io - d event and show drift rates are consistent with those from other io - related sources .
finally , s - n burst events are seen in high spectral and temporal resolution and our data strongly support the co - spatial origins of these events . .
And you have already written the first three sentences of the full article: strong bursts of decametric radio emission below 40 mhz were identified by @xcite as originating from jupiter .
the emission in the decametric range ( referred to as dam range hereafter ) occurs from 3 mhz to 39.5 mhz , although specific io - related dam arcs have been seen at frequencies below 2 mhz @xcite .
jovian dam has a peak of the spectral power at a frequency of about 10 mhz , and average fluxes of @xmath1 mjy watt m@xmath2 hz@xmath3 , as well as s - bursts that can be 100 times stronger @xcite ..
Please generate the next two sentences of the article | the lower - limit on observations from ground - based observatories is generally above 5 to 10 mhz due to attenuation by the earth s ionosphere . from ground - based and space - based observations
, it has been long known that much of the jupiter dam emission is influenced by the satellite io @xcite , and that some emissions not related to io have been correlated with solar wind parameters @xcite . for a review see @xcite . |
8,479 | Suppose that you have an abstract for a scientific paper: the type ia supernovae observational data is one of the most important in observational cosmology nowadays . here
we present the first public version of * betocs * ( * * b**ay**e**sian * * t**ools for * * o**bservational * * c**osmology using * * s**ne ia ) , which is a powerful and high productivity tool aimed to help the theoretical physicist community investigate cosmological models using type ia supernovae ( sne ia ) observational data .
betocs is applied to the generalized chaplygin gas model ( gcgm ) , traditional chaplygin gas model ( cgm ) and @xmath0cdm , ranging from 5 to 3 free parameters , respectively .
the `` gold sample '' of 157 supernovae data is used .
it is shown that the chaplygin gas scenario is viable ( in most cases the @xmath0cdm is disfavoured ) and the quartessence scenario ( that unifies the description for dark matter and dark energy ) is favoured .
the hubble parameter ( @xmath1 ) is important and should not be fixed and it can be estimated or marginalized with or without the hubble space telescope prior .
pacs number(s ) : 98.80.bp , 98.80.es , 04.60.gw .
And you have already written the first three sentences of the full article: the type ia supernovae ( sne ia ) observational data has forced us to discard or change the majority of theoretical cosmological models supposed to be correct until the second half of the last decade @xcite .
the crossing of the sne ia statistics with other observational data , like the anisotropy of the cosmic microwave background radiation ( cmbr ) @xcite , gravitational lensing @xcite , the x - ray gas mass fraction of galaxy clusters @xcite , etc , leads to a scenario where the matter content of the universe is described by an unclustered component of negative pressure , the dark energy , and a clustered component of zero pressure , the cold dark matter .
there are many candidate for dark energy , the most natural seems to be the cosmological constant @xcite , since it can be connected with the vacuum energy in quantum field theory @xcite , but the small value resulting from observations for the energy density of the cosmological constant term yields a discrepancy of about @xmath2 orders of magnitude with the theoretically predicted value @xcite . among many other possibilities , for example.
Please generate the next two sentences of the article | there is the quintessence model with scalar fields @xcite . here
we will focus on the chaplygin gas models ( cgm ) @xcite . |
8,480 | Suppose that you have an abstract for a scientific paper: many studies have shown that we can gain additional information on time series by investigating their accompanying complex networks . in this work ,
we investigate the fundamental topological and fractal properties of recurrence networks constructed from fractional brownian motions ( fbms ) .
first , our results indicate that the constructed recurrence networks have exponential degree distributions ; the average degree exponent @xmath0 increases first and then decreases with the increase of hurst index @xmath1 of the associated fbms ; the relationship between @xmath1 and @xmath0 can be represented by a cubic polynomial function .
we next focus on the motif rank distribution of recurrence networks , so that we can better understand networks at the local structure level .
we find the interesting superfamily phenomenon , i.e. the recurrence networks with the same motif rank pattern being grouped into two superfamilies .
last , we numerically analyze the fractal and multifractal properties of recurrence networks .
we find that the average fractal dimension @xmath2 of recurrence networks decreases with the hurst index @xmath1 of the associated fbms , and their dependence approximately satisfies the linear formula @xmath3 , which means that the fractal dimension of the associated recurrence network is close to that of the graph of the fbm .
moreover , our numerical results of multifractal analysis show that the multifractality exists in these recurrence networks , and the multifractality of these networks becomes stronger at first and then weaker when the hurst index of the associated time series becomes larger from 0.4 to 0.95 .
in particular , the recurrence network with the hurst index @xmath4 possess the strongest multifractality .
in addition , the dependence relationships of the average information dimension @xmath5 and the average correlation dimension @xmath6 on the hurst index @xmath1 can also be fitted well with linear functions .
our results strongly suggest that the recurrence....
And you have already written the first three sentences of the full article: methods of nonlinear time series analysis have been widely applied in physics , physiology , finance and biology .
complex network theory has become one of the most important developments in statistical physics @xcite .
recent studies have shown that complex network theory may be an effective method to extract the information embedded in time series @xcite ..
Please generate the next two sentences of the article | many complicated dynamics systems in nature and society can be described by complex networks . in a complex system ,
its elements are represented by nodes , and their interactions are represented by directed or undirected edges . |
8,481 | Suppose that you have an abstract for a scientific paper: we defend a natural division of the energy density , energy flux and momentum density of electromagnetic waves in linear media in electromagnetic and material parts . in this division ,
the electromagnetic part of these quantities have the same form as in vacuum when written in terms of the macroscopic electric and magnetic fields , the material momentum is calculated directly from the lorentz force that acts on the charges of the medium , the material energy is the sum of the kinetic and potential energies of the charges of the medium and the material energy flux results from the interaction of the electric field with the magnetized medium .
we present reasonable models for linear dispersive non - absorptive dielectric and magnetic media that agree with this division .
we also argue that the electromagnetic momentum of our division can be associated with the electromagnetic relativistic momentum , inspired on the recent work of barnett [ phys .
rev .
lett . * 104 * , 070401 ( 2010 ) ] that showed that the abraham momentum is associated with the kinetic momentum and the minkowski momentum is associated with the canonical momentum . .
And you have already written the first three sentences of the full article: the discussion of the correct form of the energy - momentum tensor of electromagnetic waves in material media has been the subject of a hot debate for more than one century @xcite .
the two most famous proposals were made by minkowski and abraham on the beginning of last century @xcite and have distinct predictions for the momentum of light in a medium .
the abraham formulation predicts that an electromagnetic wave with total momentum @xmath0 in vacuum decreases its momentum to @xmath1 after entering a dielectric medium with refraction index @xmath2 , while the minkowski formulation predicts that the momentum of the wave is increased to @xmath3 after entering the medium ..
Please generate the next two sentences of the article | several experiments on this subject were made in the past 60 years @xcite , many of them with the purpose of solving the debate , but the fact is that no decision can be made on experimental grounds . as it was pointed out by penfield and haus @xcite , the abraham , minkowski and other electromagnetic energy - momentum tensors are accompanied by distinct material energy - momentum tensors . and when the properties of the material energy - momentum tensors are carefully taken into account , both formulations predict the same experimental results .
a recent review of this debate can be seen in ref . |
8,482 | Suppose that you have an abstract for a scientific paper: we use maximal entropy random walk ( merw ) to study the trapping problem in dendrimers modeled by cayley trees with a deep trap fixed at the central node .
we derive an explicit expression for the mean first passage time from any node to the trap , as well as an exact formula for the average trapping time ( att ) , which is the average of the source - to - trap mean first passage time over all non - trap starting nodes .
based on the obtained closed - form solution for att , we further deduce an upper bound for the leading behavior of att , which is the fourth power of @xmath0 , where @xmath1 is the system size .
this upper bound is much smaller than the att of trapping depicted by unbiased random walk in cayley trees , the leading scaling of which is a linear function of @xmath1 .
these results show that merw can substantially enhance the efficiency of trapping performed in dendrimers . .
And you have already written the first three sentences of the full article: dendrimers are an important class of artificial macromolecules with a treelike structure , which are synthesized by repeating units in a hierarchical self - similar fashion around a central core @xcite .
their unique structural features make them promising candidates for a broad range of potential applications such as light harvesting antennae @xcite and molecular amplifiers @xcite , the latter of which can be used as efficient platforms for drug delivery @xcite . in view of their practical significance ,
thus far , dendrimers have received extensive attention within the scientific community @xcite . in the context of light harvesting by dendrimers , it is the large number of absorbing elements at the periphery and an efficient transfer of the absorbed energy to the center that make dendrimers work as antennas @xcite ..
Please generate the next two sentences of the article | generally , light harvesting can be described as a trapping process with a ( fluorescent ) trap located at the center . a primary quantity related to trapping
is average trapping time ( att ) , which is the average of mean first - passage time ( mfpt ) @xcite to the target over all starting nodes , where mfpt from a node to the trap is the expected time steps needed for a walker starting off from this node to visit the trap for the first time . |
8,483 | Suppose that you have an abstract for a scientific paper: the emission spectrum has been calculated of a homogeneous pure hydrogen layer , which parameters are typical for a flare on a red dwarf .
the ionization and excitation states were determined by the solution of steady - state equations taking into account the continuum and all discrete hydrogen levels .
we consider the following elementary processes : electron - impact transitions , spontaneous and induced radiative transitions , and ionization by the bremsstrahlung and recombination radiation of the layer itself .
the biberman
holstein approximation was used to calculate the scattering of line radiation .
asymptotic formulae for the escape probability are obtained for a symmetric line profile taking into account the stark and doppler effects .
the approximation for the core of the h@xmath0 line by a gaussian curve has been substantiated .
the spectral intensity of the continuous spectrum , the intensity of the lines of the balmer series and the magnitude of the balmer jump have been calculated .
the conditions have been determined for which the balmer jump and the emission line intensities above the continuum decrease to such low values that the emission spectrum can be assumed to be continuum as well as the conditions at which the emission spectrum becomes close to the blackbody . .
And you have already written the first three sentences of the full article: @xcite were the first who formulated the idea about the analogy of flares on red dwarf stars and on the sun .
at present it seems obvious that the physical nature of the activity of the sun and red dwarf stars is similar ( @xcite ) .
@xcite put forward the pioneering idea about the important role of gas - dynamic effects in the formation of the emission of solar flares ..
Please generate the next two sentences of the article | the authors showed that the radiative cooling of the shocked gas can be a source of the flare s emission in the optical range .
the shock wave is produced by impulsive heating of the chromosphere by suprathermal particles . |
8,484 | Suppose that you have an abstract for a scientific paper: we prove a bosonic formula for the generating function of level - restricted paths for the infinite families of affine kac - moody algebras . in affine type
a this yields an expression for the level - restricted generalized kostka polynomials . supported by the `` stichting fundamenteel onderzoek der materie '' . ] partially supported by nsf grant dms-9800941 . ] .
And you have already written the first three sentences of the full article: let @xmath0 be an affine kac - moody algebra , @xmath1 a @xmath2-submodule of a finite direct sum @xmath3 of irreducible integrable highest weight @xmath4-modules , and @xmath5 the limit of the demazure operator for an element @xmath6 of the weyl group as @xmath7 .
the main theorem of this paper gives sufficient conditions on @xmath1 so that the formula @xmath8 holds , where @xmath9 is the character of @xmath1 .
when @xmath1 is the one - dimensional @xmath2-module generated by the dominant integral weight @xmath10 then is the weyl - kac character formula ..
Please generate the next two sentences of the article | the above result is well - known when @xmath1 is a union of demazure modules for any kac - moody algebra @xmath0 .
let @xmath11 be the derived subalgebra of @xmath0 . |
8,485 | Suppose that you have an abstract for a scientific paper: we present several methods to construct or identify families of free divisors such as those annihilated by many euler vector fields , including binomial free divisors , or divisors with triangular discriminant matrix .
we show how to create families of quasihomogeneous free divisors through the chain rule or by extending them into the tangent bundle .
we also discuss whether general divisors can be extended to free ones by adding components and show that adding a normal crossing divisor to a smooth one will not succeed . .
And you have already written the first three sentences of the full article: the goal of this note is to describe some basic operations that allow to construct new free divisors from given ones , and to classify toric free surfaces and binomial free divisors
. we mainly deal with weighted homogeneous polynomials over a field of characteristic @xmath0 , though several statements and constructions generalize to power series .
a ( formal ) _ free divisor _ is a reduced polynomial ( or power series ) @xmath1 in variables @xmath2 over a field @xmath3 such that its jacobian ideal @xmath4 is perfect of codimension @xmath5 in the polynomial or power series ring . for generalities about free divisors and their importance in singularity theory.
Please generate the next two sentences of the article | we refer to , say , @xcite and the references therein .
a determinantal characterization of free divisors is due to k. saito @xcite : a reduced polynomial @xmath1 is a free divisor if and only if there exists a matrix @xmath6 of size @xmath7 with entries in the relevant polynomial or power series ring such that @xmath8 and @xmath9 , where @xmath10 is the usual gradient of @xmath1 . in that case @xmath6 |
8,486 | Suppose that you have an abstract for a scientific paper: i calculate , at one loop in staggered chiral perturbation theory , the matrix elements of the complete set of five local operators that may contribute to @xmath0 mixing both in the standard model and in beyond - the - standard - model theories .
lattice computations of these matrix elements by the fermilab lattice / milc collaborations ( and earlier by the hpqcd collaboration ) convert a light staggered quark into a naive quark , and construct the relevant 4-quark operators as local products of two local bilinears , each involving the naive light quark and the heavy quark .
this particular representation of the operators turns out to be important in the chiral calculation , and it results in the presence of `` wrong - spin '' operators , whose contributions however vanish in the continuum limit . if the matrix elements of all five operators are computed on the lattice , then no additional low energy constants are required to describe wrong - spin chiral effects . .
And you have already written the first three sentences of the full article: the mixing of neutral @xmath0 mesons provides a fertile area for precision tests of the standard model . the fact that the mixing is a second order weak process and is also suppressed by small ckm angles in the standard model makes it sensitive to new physics . in order to take full advantage of experimental measurements of the mixing
, one needs to determine the hadronic matrix elements of the effective weak operators . for @xmath0 mixing the relevant operators are local four - quark operators with @xmath1 , where @xmath2 is @xmath2-quark number , and the relevant states are @xmath3 and @xmath4 mesons or @xmath5 and @xmath6 mesons .
a first - principle evaluation of such operator matrix elements is possible with lattice qcd ..
Please generate the next two sentences of the article | lattice computations usually involve an extrapolation in light quark masses to the physical up and down masses , and always require an extrapolation in lattice spacing @xmath7 to @xmath8 , the continuum .
these extrapolations can be controlled by using a version of chiral perturbation theory that includes the effects of the discretization errors associated with the choice of lattice action . |
8,487 | Suppose that you have an abstract for a scientific paper: in an experimental study of single enzyme reactions , it has been proposed that the rate constants of the enzymatic reactions fluctuate randomly , according to a given distribution . to quantify the uncertainty arising from random rate constants ,
it is necessary to investigate how one can simulate such a biochemical system . to do this
, we will take the gillespie s stochastic simulation algorithm for simulating the evolution of the state of a chemical system , and study a modification of the algorithm that incorporates the random rate constants .
in addition to simulating the waiting time of each reaction step , the modified algorithm also involves simulating the random fluctuation of the rate constant at each reaction time .
we consider the modified algorithm in a general framework , then specialize it to two contrasting physical models , one in which the fluctuations occur on a much faster time scale than the reaction step , and the other in which the fluctuations occur much more slowly .
the latter case was applied to the single enzyme reaction system , using in part the metropolis - hastings algorithm to enact the given distribution on the random rate constants .
the modified algorithm is shown to produce simulation outputs that are corroborated by the experimental results .
it is hoped that this modified algorithm can subsequently be used as a tool for the estimation or calibration of parameters in the system using experimental data . .
And you have already written the first three sentences of the full article: gillespie s stochastic simulation algorithm has recently gained popularly as a method for simulating the evolution of biochemical systems .
its advantage lies in its ability to capture the inherent stochasticity present in a chemical reaction system , and provide a full statistical description of the evolution of the system a point not addressed by traditional mass action theory , which , through a mathematical model of ordinary differential equations ( odes ) , is able to capture only ensemble averaged behaviour and assumes a continuum of reactant concentrations .
despite the fact that the deterministic mass action theory and the stochastic model of gillespie s algorithm are equivalent in the limit of large system sizes ( both assuming the well - mixed assumption ) , it is widely accepted that the stochastic model is more appropriate for biochemical applications , for the reason that biochemical systems commonly involve very low numbers of reactant molecules ..
Please generate the next two sentences of the article | however , recent studies in the phenomenon of dynamic disorder of biomolecules reveal further stochasticity in certain biochemical systems that has yet to be accounted for by either of the two models : biochemical systems with randomly fluctuating rate constants .
dynamic disorder refers to the fluctuation of the conformational state of a biomolecule , which may be attributed to the minimization of energy landscapes @xcite . |
8,488 | Suppose that you have an abstract for a scientific paper: where do new markets come from ?
i construct a network model in which national markets are nodes and flows of recorded music between them are links and conduct a longitudinal analysis of the global pattern of trade in the period 1976 to 2010 .
i hypothesize that new export markets are developed through a process of transitive closure in the network of international trade .
when two countries markets experience the same social influences , it brings them close enough together for new homophilous ties to be formed .
the implication is that consumption of foreign products helps , not hurts , home - market producers develop overseas markets , but only in those countries that have a history of consuming the same foreign products that were consumed in the home market .
selling in a market changes what is valued in that market , and new market formation is a consequence of having social influences in common . .
And you have already written the first three sentences of the full article: many innovative industries produce goods or services that have an interpreted , or `` cultural '' component to the value placed on them by consumers , in that tastes differ in different markets : just because a product is `` big in japan '' does not mean it is `` big '' elsewhere .
the same could be said at the level of national industries : as figure 1 illustrates , for example , although there may be a market for my home country s music in japan , there may not be one in italy .
we are told that the division of labor is limited by the extent of the market , but for information goods the more fundamental issue may be what the extent of the market is limited by : why do only certain other countries have substantial demand for my industry s innovative products ?.
Please generate the next two sentences of the article | the question has substantial practical consequences .
for individual producers and distributors of information goods , selling to foreign markets can be highly profitable due to negligible marginal costs for information goods ( wildman and siwek 1988 , parker and van alstyne , 2005 ) ; for whole economies , the presence of high - value export industries can drive overall growth and development ( amsden , 2001 ; hausmann , hwang , and rodrik , 2007 ; hidalgo et al , 2007 ) . despite the importance of the question |
8,489 | Suppose that you have an abstract for a scientific paper: this paper investigates the shadow of a charged rotating non - commutative black hole . for this purpose
, we first formulate the null geodesics and study the effects of non - commutative charge on the photon orbit .
we then explore the effect of spin , angle of inclination as well as non - commutative charge on the silhouette of the shadow .
it is found that shape of the shadow deviates from the circle with the decrease in the non - commutative charge .
we also discuss observable quantities to study the deformation and distortion in the shadow cast by the black hole which decreases for small values of non - commutative charge .
finally , we study the shadows in the presence of plasma .
we conclude that the non - commutativity has a great impact on the black hole shadow .
* keywords : * non - commutative geometry ; black hole ; shadow . + * pacs : * 95.30.sf ; 04.70.-s . ; 04.62.+v . .
And you have already written the first three sentences of the full article: black holes ( bhs ) are the end products of a complete gravitational collapse of the massive star surrounded by a boundary from which nothing can escape even light . despite their dark nature , bhs exist in the environment of the brightest objects of the universe .
black hole does not shine but the accreting gas that spirals around , emits radiations and then disappears when reaches the event horizon .
generally , a bh casts a shadow in an emitting medium which arises due to the bending of light that originates near the horizon and travels through the accretion flow ..
Please generate the next two sentences of the article | the shape of a shadow depends on the photon capture sphere resulting from strong bending of light perceived by a distant observer .
the shadow can actually depict the compact object ( bh or naked singularity ) as its appropriate observations can provide information about the parameters as well as spacetime geometry around the compact object . |
8,490 | Suppose that you have an abstract for a scientific paper: the x - ray spectra of the magnetar candidates are customarily fitted with an empirical , two component model : an absorbed blackbody and a power - law . however
, the physical interpretation of these two spectral components is rarely discussed .
it has been recently proposed that the presence of a hot plasma in the magnetosphere of highly magnetized neutron stars might distort , through efficient resonant cyclotron scattering , the thermal emission from the neutron star surface , resulting in production of non - thermal spectra . here
we discuss the resonant cyclotron scattering ( rcs ) model , and present its xspec implementation , as well as preliminary results of its application to anomalous x - ray pulsars and soft gamma - ray repeaters .
example.eps gsave newpath 20 20 moveto 20 220 lineto 220 220 lineto 220 20 lineto closepath 2 setlinewidth gsave .4 setgray fill grestore stroke grestore .
And you have already written the first three sentences of the full article: anomalous x - ray pulsars ( axps ) and soft gamma - ray repeaters ( sgrs ) are a small class of slowly rotating ( 5 - 12 s ) neutron stars with emission properties much at variance with those of ordinary x - ray pulsars , both the young radio pulsars and the x - ray binary pulsars .
they are called `` anomalous '' because their high x - ray luminosity ( @xmath0 erg / s ) can not be easily explained in terms of the conventional processes which apply to other classes of pulsars , i.e. accretion from a binary companion or injection of rotational energy in the pulsar wind / magnetosphere . on the other hand , measurements of spin periods and period derivatives , when the latter are interpreted as due to electromagnetic dipolar losses ,
suggest that these objects may host `` magnetars '' , i.e. neutron stars endowed with an ultra - strong magnetic field ( @xmath1 g , see duncan & thompson 1992 ; thompson & duncan 1993 , 1996 ) ..
Please generate the next two sentences of the article | the magnetar scenario appears so far very promising in explaining both the main energy source of these objects ( the decay of the super - strong field ) and the emission of the short , energetic bursts .
moreover , the magnetar scenario can account for the properties of giant flares , extremely energetic transient events ( @xmath2 erg / s ) detected from sgrs . however , |
8,491 | Suppose that you have an abstract for a scientific paper: some ostrowski type inequalities via cauchy s mean value theorem and applications for certain particular instances of functions are given . .
And you have already written the first three sentences of the full article: the following result is known in the literature as ostrowski s inequality @xcite .
[ t1]let @xmath0 \rightarrow \mathbb{r}$ ] be a differentiable mapping on @xmath1 with the property that @xmath2 for all @xmath3 then @xmath4 \left ( b - a\right ) m , \label{1.1}\]]for all @xmath5 .$ ] the constant @xmath6 is best possible in the sense that it can not be replaced by a smaller constant . in @xcite
, the author has proved the following ostrowski type inequality ..
Please generate the next two sentences of the article | [ t2]let @xmath0 \rightarrow \mathbb{r}$ ] be continuous on @xmath7 $ ] with @xmath8 and differentiable on @xmath9 let @xmath10 and assume that @xmath11 then we have the inequality @xmath12 for any @xmath13 where for @xmath14@xmath15 @xmath16 ^{\frac{1}{p}},\;\text{is the } p-\text{logarithmic mean}\;p\in \mathbb{r}\backslash \left\ { -1,0\right\ } , \ ] ] and @xmath17 another result of this type obtained in the same paper is : [ t3]let @xmath0 \rightarrow \mathbb{r}$ ] be continuous on @xmath7 $ ] ( with @xmath8 ) and differentiable on @xmath9 if @xmath18 then we have the inequality @xmath19 ^{b - x}}{\left [ i\left ( a , x\right ) \right ] ^{x - a}}\right ] + 2\left ( x - a\right ) \ln x\right ] \label{1.3}\ ] ] for any @xmath13 where for @xmath20@xmath21 if some local information around the point @xmath22 is available , then we may state the following result as well @xcite .
[ t4]let @xmath0 \rightarrow \mathbb{r}$ ] be continuous on @xmath7 $ ] and differentiable on @xmath9 let @xmath23 and assume , for a given @xmath13 we have that @xmath24then we have the inequality @xmath25 m_{p}\left ( x\right ) .\end{gathered}\ ] ] for recent results in connection to ostrowski s inequality see the papers @xcite,@xcite and the monograph @xcite . |
8,492 | Suppose that you have an abstract for a scientific paper: reflection of x rays from cool material around a black hole is one of the few observational diagnostics of the accretion flow geometry .
models of this reflected spectrum generally assume that the accretion disk can be characterized by material in a single ionization state .
however , several authors have recently stressed the importance of the classic ionization instability for x ray irradiated gas in hydrostatic balance .
this instability leads to a _ discontinuous _ transition in the vertical structure of the disk , resulting in a hot ionized skin above much cooler material .
if the compton temperature of the skin is high then even iron is completely ionized , and the skin does not produce any spectral features .
these new models , where the ionization structure of the disk is calculated self consistently , require an excessive amount of computing power and so are difficult to use in directly fitting observed x ray spectra .
instead , we invert the problem by simulating x ray spectra produced by the new reflection models , and then fit these with the old , single zone reflection models , to assess the extent to which the derived accretion geometry depends on the reflection model used .
we find that the single zone ionization models can severely underestimate the covering fraction of the `` cold '' material as seen from the x ray source if the optical depth in the ionized skin is of order unity , and that this can produce an apparent correlation between the covering fraction and the x ray spectral index similar in nature to that reported by zdziarski , lubiski and smith ( 1999 ) .
accretion , accretion disks radiative transfer line : formation x rays : general radiation mechanisms : non - thermal .
And you have already written the first three sentences of the full article: calculations of the reflected spectrum expected from x ray illumination of an accretion disk around a black hole are extremely important .
the reflected continuum and especially its associated iron k@xmath0 fluorescence line ( see e.g. basko , sunyaev & titarchuk 1974 ; lightman & white 1988 ; george & fabian 1991 ; matt , perola & piro 1991 ) are perhaps the only spectral features expected from optically thick material in the vicinity of a black hole , so can be used to test theoretical models of accretion in strong gravity ( fabian et al .
1989 , dabrowski et al ..
Please generate the next two sentences of the article | 1997 ) .
this is especially relevant since there is much current debate on the structure of the accretion flow . |
8,493 | Suppose that you have an abstract for a scientific paper: based on a deep imaging survey , we present the first homogeneous star formation history ( sfh ) of the fornax dwarf spheroidal ( dsph ) galaxy .
we have obtained two - filter photometry to a depth of @xmath0 over the entire surface of fornax , the brightest dsph associated with the milky way , and derived its sfh using a cmd - fitting technique .
we show that fornax has produced the most complex star formation and chemical enrichment histories of all the milky way dsphs .
this system has supported multiple epochs of star formation .
a significant number of stars were formed in the early universe , however the most dominant population are the intermediate age stars .
this includes a strong burst of star formation approximately @xmath1 gyr ago .
significant population gradients are also evident .
similar to other dsphs , we have found that recent star formation was concentrated towards the centre of the system .
furthermore , we show that the central region harboured a faster rate of chemical enrichment than the outer parts of fornax . at the centre , the ancient stars ( age @xmath2 gyr )
display a mean metallicity of [ fe / h ] @xmath3 , with evidence for three peaks in the metallicity distribution .
overall , enrichment in fornax has been highly efficient : the most recent star formation burst has produced stars with close to solar metallicity .
our results support a scenario in which fornax experienced an early phase of rapid chemical enrichment producing a wide range of abundances .
star formation gradually decreased until @xmath44 gyr ago , when fornax experienced a sudden burst of strong star formation activity accompanied by substantial chemical enrichment .
weaker star forming events followed , and we have found tentative evidence for stars with ages less than 100 myr . .
And you have already written the first three sentences of the full article: the dwarf spheroidal galaxies ( dsphs ) are the least luminous galaxies known .
they display remarkably high mass - to - light ratios ( @xmath4100 to 1000 ) , and the stars in each system are known to reside at the centre of a massive dark halo ( @xmath5 ) which extends far beyond the observed limiting radii @xcite . in terms of stellar population , these systems can have surprisingly complex star formation histories ( sfhs ) . all dsphs contain a population of ancient stars @xcite , however some ( such as fornax ) have been able to maintain multiple epochs of star formation and chemical enrichment over a hubble time .
these systems are relatively simple environments compared to larger galaxies , and are therefore a starting point in the study of star formation and enrichment ..
Please generate the next two sentences of the article | simulations suggest a cyclical process , in which the gas collapses to form stars , is then chemically enriched and blown out by pockets of massive star formation , and then collapses again to repeat the cycle . @xcite
propose a time frame of @xmath4250 myr for a single cycle . |
8,494 | Suppose that you have an abstract for a scientific paper: motion camouflage is a stealth strategy observed in nature .
we formulate the problem as a feedback system for particles moving at constant speed , and define what it means for the system to be in a state of motion camouflage .
( here we focus on the planar setting , although the results can be generalized to three - dimensional motion . )
we propose a biologically plausible feedback law , and use a high - gain limit to prove accessibility of a motion camouflage state in finite time .
we discuss connections to work in missile guidance .
we also present simulation results to explore the performance of the motion camouflage feedback law for a variety of settings . .
And you have already written the first three sentences of the full article: motion camouflage is a stealth strategy employed by various visual insects and animals to achieve prey capture , mating or territorial combat . in one type of motion camouflage ,
the predator camouflages itself against a fixed background object so that the prey observes no relative motion between the predator and the fixed object . in the other type of motion camouflage ,
the predator approaches the prey such that from the point of view of the prey , the predator always appears to be at the same bearing ..
Please generate the next two sentences of the article | ( in this case , we say that the object against which the predator is camouflaged is the point at infinity . ) assuming that the prey can readily observe optical flow , but only poorly sense looming , this type of motion by the predator is then difficult to detect by the prey .
for example , insects with compound eyes are quite sensitive to optical flow ( which arises from the transverse component of the relative velocity between the predator and the prey ) , but are far less sensitive to slight changes in the size of images ( which arise from the component of the relative velocity between the predator and prey along the line between them ) |
8,495 | Suppose that you have an abstract for a scientific paper: first - principles full potential linearized augmented plane wave ( flapw ) calculations have been performed for lattice - mismatched common - atom iii - v interfaces . in particular , we have examined the effects of epitaxial strain and ordering direction on the valence band offset in [ 001 ] and [ 111 ] gasb / insb and inas / insb superlattices , and found that the valence band maximum is always _ higher _ at the insb side of the heterojunction , except for the common - anion system grown on an insb substrate .
the comparison between equivalent structures having the same substrate lattice constant , but different growth axis , shows that for comparable strain conditions , the ordering direction slightly influences the band line - up , due to small differences of the charge readjustment at the [ 001 ] and [ 111 ] interfaces . on the other hand
, strain is shown to strongly affect the vbo ; in particular , as the pseudomorphic growth conditions are varied , the bulk contribution to the band line - up changes markedly , whereas the interface term is almost constant . on the whole ,
our calculations yield a band line - up that decreases linearly as the substrate lattice constant is increased , showing its high tunability as a function of different pseudomorphic growth conditions .
finally , the band line - up at the lattice matched inas / gasb interface determined using the transitivity rule gave perfect agreement between predicted and experimental results . .
And you have already written the first three sentences of the full article: in the last few years band offset engineering " ( _ i.e. _ the possibility of tuning the electronic and transport properties of semiconductor heterojunctions through modifications of their valence band offset ( vbo ) induced by strain , growth process , number of layers etc . )
has attracted great attention for both scientific and technological reasons @xcite . only recently , however , have lattice mismatched heterostructures begun to realize their potential , due to new developments in preparation techniques which finally allowed pseudomorphic crystal growth without misfit dislocations @xcite . in a parallel way ,
some theoretical works @xcite focused on strained heterojunctions , but still much effort is needed to understand what mainly affects the band line - up at the interface . in this work , we consider homopolar isovalent heterostructures ..
Please generate the next two sentences of the article | in particular , we examine iii - v superlattices ( sls ) , namely the common - anion system gasb / insb ( lattice mismatch of 5.7 @xmath0 ) and the common - cation system inas / insb ( lattice mismatch of 6.4 @xmath0 ) , concentrating on the effect of ordering direction and strain conditions determined by sl pseudomorphic growth on a given substrate . _
ab - initio _ self - consistent full potential linearized augmented plane wave flapw @xcite local density calculations were performed for ( gasb)@xmath1/(insb)@xmath1 and ( inas)@xmath1/(insb)@xmath1 sls , grown along the [ 001 ] ( tetragonal symmetry ) and [ 111 ] ( trigonal symmetry ) directions , in which the interface was represented by three alternating layers of each binary constituent ( 12 atoms in each unit cell ) . in what follows , |
8,496 | Suppose that you have an abstract for a scientific paper: the taurus tunable filter ( ttf ) has now been in regular use for seven years on the anglo - australian telescope ( aat ) .
the instrument was also used for three years ( 19961999 ) on the william herschel telescope ( wht ) .
we present a brief review of the different applications in order to illustrate the versatility of tunable filters in optical / ir spectrophotometric imaging .
tunable filters are now planned or under development for 6 - 10 m class telescopes which ensures their use for years to come .
@xmath0 anglo - australian observatory , po box 296 , epping , nsw 2121 + [email protected] + @xmath1 dept . of astrophysics & optics ,
school of physics , university of new south wales , nsw 2052 + [email protected] + .
And you have already written the first three sentences of the full article: we provide a short review of the first seven years of observing with the taurus tunable filter at the aat ; for the first three years , the ttf was also used at the wht .
the instrument has had most of its use on the aat where it gets between 1015% of the telescope time scheduled by the patt ( uk ) and atac ( australia ) committees . in a nutshell
, the ttf allows for wide - field ( 10@xmath2 ) spectrophotometric imaging from 370 nm to 1000 nm with resolving powers generally in the range 100 to 1000 ..
Please generate the next two sentences of the article | an important feature of the instrument is the use of charge shuffling synchronized to band switching in order to greatly suppress systematic errors associated with conventional imaging .
another aspect of the ttf is time series readout coupled to band switching which has lead to important new work on compact variable sources . |
8,497 | Suppose that you have an abstract for a scientific paper: it is shown that it is possible to perform a model - independent extraction of the ckm unitarity triangle angle @xmath0 using only the decays @xmath1with
@xmath2and @xmath1with flavour - specific @xmath3 decays .
the proposed method can also utilise the @xmath1data with @xmath4-eigenstate decays of the @xmath3 meson in a model - independent way . .
And you have already written the first three sentences of the full article: among the fundamental parameters of the standard model of particle physics , the angle @xmath5 of the unitarity triangle formed from elements of the cabibbo - kobayashi - maskawa quark mixing matrix @xcite has a particular importance .
not only is it one of the least well determined fundamental parameters of the standard model , it is also the only @xmath4-violating parameter that can be measured using only tree - level decays @xcite .
the precise determination of @xmath0 is thus a critical element of the programme towards understanding the baryon asymmetry of the universe , and is one of the main objectives of planned future @xmath6 physics experiments ( see , for example , @xcite ) ..
Please generate the next two sentences of the article | a method to measure the ckm phase @xmath0 in @xmath1decays by comparing the dalitz plot distribution obtained when the neutral @xmath3 meson is reconstructed in @xmath4 eigenstates to that when flavour - specific states are used has been proposed recently @xcite .
the method builds on the original proposal of gronau , london and wyler ( glw ) @xcite for a similar analysis using @xmath7decays , and exploits the fact that @xmath4 violation effects are expected to be enhanced in @xmath8 decays since the interfering amplitudes are of comparable magnitude @xcite . |
8,498 | Suppose that you have an abstract for a scientific paper: using multi - epoch observations of the stripe 82 region done by sloan digital sky survey , we measure precise statistical proper motions of the stars in the sagittarius stellar stream .
the multi - band photometry and sdss radial velocities allow us to efficiently select sgr members and thus enhance the proper motion precision to @xmath0 0.1masyr@xmath1 .
we measure separately the proper motion of a photometrically selected sample of the main sequence turn - off stars , as well as of a spectroscopically selected sgr giants .
the data allow us to determine the proper motion separately for the two sgr streams in the south found in @xcite .
together with the precise velocities from sdss , our proper motion provide exquisite constraints of the 3-d motions of the stars in the sgr streams . .
And you have already written the first three sentences of the full article: the disintegrating sagittarius ( sgr ) dwarf galaxy remains a riddle , wrapped in a mystery , inside an enigma .
large scale photometric surveys , such as the two micron all - sky survey ( 2mass ) and the sloan digital sky survey ( sdss ) have now revealed the structure of the tidal tails of the sgr over more than @xmath2 radians on the sky @xcite . by tallying all the stellar debris in the streams and remnant , we now know that the progenitor galaxy had a luminosity of @xmath3 , comparable to the present day small magellanic cloud @xcite .
the ingestation of such a large progenitor , together with its dismantling under the actions of the galactic tides , can provide us with a wealth of information about both the galaxy and the sgr , if we can only decode it ..
Please generate the next two sentences of the article | radial velocities , and sometimes metallicities and chemical abundances , are now known for many hundreds of stars in the sgr tails ( e.g. , * ? ? ?
* ; * ? ? ? |
8,499 | Suppose that you have an abstract for a scientific paper: wmap s detection of the sunyaev - zeldovich effect ( sze ) at a much reduced level among several large samples of rich clusters is interpreted in terms of conventional physics .
it is by now widely believed that the central soft x - ray and euv excess found in some clusters can not be of thermal origin , due to problems with rapid gas cooling and the persistent non - detection of the o vii line , but may arise from inverse - compton scattering between intracluster relativistic electrons and the cosmic microwave background ( cmb ) .
in fact , recently chandra and xmm observations of the soft x - rays from abell 3112 are well fitted by the sum of a power law and a thermal virialized gas component of comparable luminosities .
therefore the missing sze flux could simply be due to an overestimate of the central density of virialized electrons which scatter the cmb .
we also considered if higher energy electrons drawn from the same power - law population as those responsible for the soft excess may synchrotron radiate in the intracluster magnetic field of strength b @xmath0 a few @xmath1 g to produce cluster microwave emissions in the wmap passbands that account for the missing sze flux .
either explanation of the wmap anomaly would bolster the current model of central cluster soft excesses , viz .
non - thermal activities prevail in the core of at least some clusters
. the energetic electrons may originate from agn jet injection , then distributed cluster - wide with accompanying _ in situ _ fermi acceleration , by alfven waves .
however the missing thermal electron explanation provides a less demanding model . .
And you have already written the first three sentences of the full article: in a recent paper , lieu , mittaz , zhang 2006 ( lmz06 ) published the hitherto most comprehensive direct correlation of the _ wilkinson microwave anisotropy probe _ first year ( wmap1 ) data with the x - ray data of rosat and asca , in search for the sze in the temperature of the cosmic microwave background ( cmb ) along the directions to 31 randomly chosen rich clusters located above the galactic plane .
the wmap1 passbands being analyzed cover the frequency range of 41 94 ghz .
this investigation led to the astonishing finding that on average the level of sze detected by wmap1 is no deeper than the intrinsic cmb primary anisotropy as seen by wmap in directions of blank sky ( i.e. away from rich clusters and groups ) , and in any case accounts only for 1/3 to 1/4 of the level expected from the x - ray measurements of the sample clusters , moreover , lmz06 explored and excluded a variety of possible reasons for the discrepancy , including emission by radio point sources in the clusters , which fail by a large margin to deliver sufficient flux to explain the apparent lack of sze in the wmap1 w - band of 94 ghz . the results of lmz06 were corroborated recently by bielby & shanks 2007 , which presented a similar correlation study between wmap3 and x - ray observations by chandra and rosat , and likewise reported a substantially less than expected sze in the wmap3 data for a much larger sample size than the 31 clusters of lmz06 ..
Please generate the next two sentences of the article | the additional information provided by bielby & shanks 2007 also included a ` truncation test ' where the authors abruptly cut off the x - ray gas profiles of the chandra cluster sample at a radius as small as 2 arcmin , and still found a sze discrepancy of a factor of two along the central line - of - sight .
thus the anomaly is real and must be resolved . |
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