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8,200 | Suppose that you have an abstract for a scientific paper: the `` advanced spectral library ( astral ) '' project ( pi = t. ayres ) consists of two treasury programs : the cycle 18 `` cool stars '' ( go-12278 ) program and the cycle 21 `` hot stars '' ( go-13346 ) program .
the primary goal of these programs is to collect , for the use of the astronomical community over the coming decades , a definitive set of representative , high - resolution ( r@xmath030,000 - 100,000 ) , high signal / noise ( s / n@xmath1100 ) spectra , with full uv coverage ( @xmath01150 - 3100 ) of prototypical stars across the hr diagram , utilizing the high - performance space telescope imaging spectrograph ( stis ) .
the cycle 18 program obtained spectra of 8 f - m evolved late - type stars , while the cycle 21 program is in the process of observing 21 early - type stars , which span a broad range of spectral types between early - o and early - a .
all of these data will be available from the hst archive and , in post - processed and merged form , at http://casa.colorado.edu/@xmath0ayres / astral/. these data will enable investigations of a broad range of problems stellar , interstellar , and beyond for many years into the future .
we describe here the details of the observing programs , including the program targets and the observing strategies utilized to optimize the quality of the spectra , and present some illustrative examples of the on - going scientific analyses , including a study of the outer atmospheres and winds of the two evolved m stars in the sample and a first look at a `` high definition '' uv spectrum of a magnetic chemically peculiar `` ap '' star . .
And you have already written the first three sentences of the full article: over the past three years , two of the largest - ever hst stellar spectroscopic guest observer programs have been undertaken . the `` advanced spectral library ( astral ) '' project ( pi = t. ayres ) consists of two treasury programs , the first in cycle 18 on `` cool stars '' ( go-12278 ) and the second in the current cycle 21 on `` hot stars '' ( go-13346 ) .
these programs are designed to collect a definitive set of representative , high - resolution ( r@xmath030,000 - 100,000 ) , high signal / noise ( s / n@xmath1100 ) spectra , with full uv coverage ( @xmath01150 - 3100 ) of prototypical stars across the hr diagram .
the space telescope imaging spectrograph ( stis ) is ideally suited for this purpose and is the sole instrument used for the acquisition of the program spectra ..
Please generate the next two sentences of the article | the 8 f - m evolved late - type stars observed in astral / cool stars include iconic objects like betelgeuse , procyon , and pollux .
in addition , this sample has been supplemented with hst observations from a separate chandra program , so that two main sequence stars ( @xmath2 cen a & b ) are included in this definitive dataset . |
8,201 | Suppose that you have an abstract for a scientific paper: we describe a method to show short time uniqueness results for viscosity solutions of general nonlocal and non - monotone second - order geometric equations arising in front propagation problems .
our method is based on some lower gradient bounds for the solution .
these estimates are crucial to obtain regularity properties of the front , which allow to deal with nonlocal terms in the equations .
applications to short time uniqueness results for the initial value problems for dislocation type equations , asymptotic equations of a fitzhugh - nagumo type system and equations depending on the lebesgue measure of the fronts are presented . .
And you have already written the first three sentences of the full article: we are concerned with the evolution of compact hypersurfaces @xmath0 moving according to the general non - local law of propagation @xmath1 where @xmath2 is the normal velocity of @xmath3 which depends , through the evolution law @xmath4 , on time , on the position of @xmath5 , on the set @xmath6 enclosed by @xmath3 , on the unit normal @xmath7 to @xmath3 at @xmath8 pointing outward to @xmath6 and on its gradient @xmath9 which carries the curvature dependence of the velocity . when such motion is local , i.e. , when @xmath4 does not depend on @xmath6 , and satisfies _ the inclusion principle _ or _
geometrical monotonicity _ ,
i.e. , when , at least formally , the inclusion @xmath10 at time @xmath11 implies @xmath12 for any @xmath13 , it is proved by souganidis and the first author @xcite that the motion can be defined and studied by the _ level set approach _ , which was introduced by osher and sethian @xcite for numerical calculations and then developed , from a theoretical point of view , by evans and spruck @xcite for the mean curvature motion and by chen , giga and goto @xcite for general velocities ..
Please generate the next two sentences of the article | this approach replaces the geometrical problem with a degenerate parabolic partial differential equation called the _ geometric _ or _ level set equation .
_ this equation is designed to describe the desired evolution via the 0-level set of its solution . |
8,202 | Suppose that you have an abstract for a scientific paper: we consider a class of minimal extensions of the standard model with an extra massive neutral gauge boson @xmath0 .
they include both family - universal models , where the extra @xmath1 is associated with @xmath2 , and non - universal models where the @xmath0 is coupled to a non - trivial linear combination of @xmath3 and the lepton flavours . after giving an estimate of the range of parameters compatible with a grand unified theory , we present the current experimental bounds , discussing the interplay between electroweak precision tests and direct searches at the tevatron . finally , we assess the discovery potential of the early lhc .
= 11.6pt .
And you have already written the first three sentences of the full article: extra neutral gauge bosons , known in the literature as @xmath0 , appear in many proposals for beyond - the - standard model ( bsm ) physics ; for a review , see for instance @xcite . here
we focus on _ minimal _ @xmath0 , previously studied in @xcite , which stand out both for their simplicity , and because they could arise in several of the above mentioned bsm scenarios , such as , _
e.g. _ , grand unified theories ( guts ) and string compactifications ..
Please generate the next two sentences of the article | following @xcite , we consider a minimal extension of the sm gauge group that includes an additional abelian factor , labeled @xmath4 , commuting with @xmath5 .
the fermion content of the sm is augmented by one right - handed neutrino per family . |
8,203 | Suppose that you have an abstract for a scientific paper: a market fix serves as a benchmark for foreign exchange ( fx ) execution , and is employed by many institutional investors to establish an exact reference at which execution takes place .
the currently most popular fx fix is the world market reuters ( wm / r ) 4 pm fix .
execution at the wm / r 4 pm fix is a service offered by fx brokers ( normally banks ) , who deliver execution at the fix provided they obtain the trade order until a certain time prior to 4 pm . in this paper , we study the market microstructure around 4 pm . we demonstrate that market dynamics can be distinguished from other times during the day through increased volatility and size of movements .
our findings question the aggregate benefit to the client base of using the 4 pm fix in its current form .
* keywords : * wm / reuters 4 pm fix , fx market microstructure , fx execution , market manipulation .
And you have already written the first three sentences of the full article: execution of foreign exchange transactions at a fixed market benchmark rate is common amongst institutional investors .
appeal lies in the fact that , particularly when tracking benchmark indices in other asset classes , currency conversion can be performed by the same underlying fx rates as employed by their target index .
furthermore , aggregation of fixing trades by market makers prior to execution increases liquidity , which , in theory , enables clients to trade large fx amounts at a trusted rate , without having to worry about best execution or the risk of moving the price ..
Please generate the next two sentences of the article | moreover , as a market fix is uniform across providers , it is also intended to build trust in client / provider relationships , as a clearly defined and measurable service arises .
the currently most important benchmark rate is the world market reuters 4 pm london fix ( wm / r 4 pm ) , which accounts for approximately @xmath0-@xmath1 of the total @xmath2 daily volume in the fx spot market @xcite . |
8,204 | Suppose that you have an abstract for a scientific paper: we present a study of the dynamics and magnetic activity of m dwarfs using the largest spectroscopic sample of low - mass stars ever assembled .
the age at which strong surface magnetic activity ( as traced by h@xmath0 ) ceases in m dwarfs has been inferred to have a strong dependence on mass ( spectral type , surface temperature ) and explains previous results showing a large increase in the fraction of active stars at later spectral types .
using spectral observations of more than 40000 m dwarfs from the sloan digital sky survey , we show that the fraction of active stars decreases as a function of vertical distance from the galactic plane ( a statistical proxy for age ) , and that the magnitude of this decrease changes significantly for different m spectral types . adopting a simple dynamical model for thin disk vertical heating , we assign an age for the activity decline at each spectral type , and
thus determine the activity lifetimes for m dwarfs .
in addition , we derive a statistical age - activity relation for each spectral type using the dynamical model , the vertical distance from the plane and the h@xmath0 emission line luminosity of each star ( the latter of which also decreases with vertical height above the galactic plane ) . .
And you have already written the first three sentences of the full article: m dwarfs are the smallest and least luminous stars on the main sequence , yet they are the most numerous of all stellar constituents and have lifetimes longer than the current age of the universe .
determining the age of an individual main sequence , field m dwarf is quite challenging .
stellar clusters would seem to provide the ideal environments for calibrating the ages of m dwarfs ( because the age of the cluster is determined ) ..
Please generate the next two sentences of the article | however , the large distances to clusters older than a few gyr ( and resulting faintness of cluster m dwarfs ) , preclude any detailed observations of the intermediate or oldest cluster resident m dwarfs
. age estimates for field m dwarfs must therefore rely on a number of techniques that piggyback on other age dating methods . |
8,205 | Suppose that you have an abstract for a scientific paper: we describe the electroproduction ratios of baryon - meson states from nucleon , inferring from the sea quarks in the nucleon using an extension of the quark model that takes into account the sea . as a result we provide , with no adjustable parameters , the predictions of ratios of exclusive meson - baryon final states:@xmath0 , @xmath1 , @xmath2 , @xmath3 , and @xmath4 .
these predictions are in agreement with the new jlab experimental data showing that sea quarks play an important role in the electroproduction .
we also predicted further ratios of exclusive reactions that can be measured and tested in future experiments .
in particular , we suggested new experiments on deuterium and tritium .
such measurements can provide crucial test of different predictions concerning the structure of nucleon and its sea quarks helping to solve an outstanding problem . finally , we computed the so called strangeness suppression factor , @xmath5 , that is the suppression of strange quark - antiquarks compared to nonstrange pairs , and we found that our finding with this simple extension of the quark model is in good agreement with the results of jlab and cern experiments .
electroproduction , strangeness , nucleon , arxiv:1601.06987 00 - 01,99 - 00 .
And you have already written the first three sentences of the full article: in particle physics , the exact hadronization process is unknown . to determine the structure of events at high and low energies a model for hadronization from first principles
is needed but it is still missing .
there have been many attempts at modeling creation within the quark model ( qm ) formalism arising from micu s suggestion @xcite that hadron decays proceed through @xmath6 pair production with vacuum quantum numbers , i.e. @xmath7 . since the @xmath6 pair corresponds to a @xmath8 quark - antiquark state , this model is known as the @xmath8 pair - creation model @xcite ..
Please generate the next two sentences of the article | new studies have been conducted by the clas collaboration @xcite .
these have tried to extract the flavor - dependence of the creation in two - body exclusive reactions . |
8,206 | Suppose that you have an abstract for a scientific paper: a binding potential of mean force ( bpmf ) is a free energy of noncovalent association in which one binding partner is flexible and the other is rigid . expanding on previous work with host - guest systems ,
i have developed a method to calculate bpmfs for protein - ligand systems .
the method is based on replica exchange sampling from multiple thermodynamic states at different temperatures and protein - ligand interaction strengths .
protein - ligand interactions are represented by interpolating precomputed electrostatic and van der waals grids . using a simple estimator for thermodynamic length
, thermodynamic states are initialized at approximately equal intervals .
the method is demonstrated on the astex diverse set , a database of 85 protein - ligand complexes relevant to pharmacy or agriculture .
fifteen independent simulations of each complex were started using poses from crystallography , docking , or the lowest - energy pose observed in the other simulations .
benchmark simulations completed within three days on a single processor .
overall , protocols initialized using the thermodynamic length estimator were system - specific , robust , and led to approximately even replica exchange acceptance probabilities between neighboring states . in most systems , the standard deviation of the bpmf converges to within 5 k@xmath0 t .
even with low variance , however , the mean bpmf was sometimes dependent on starting conditions , implying inadequate sampling . within the thermodynamic cycle , free energies estimated based on multiple intermediate states were more precise , and those estimated by single - step perturbation were less precise .
the results demonstrate that the method is promising , but that ligand pose sampling and phase space overlap can sometimes prevent precise bpmf estimation .
the software used to perform these calculations , alchemical grid dock ( algdock ) , is available under the open - source mit license at https://github.com / ccbatiit / algdock/. .
And you have already written the first three sentences of the full article: fast and accurate predictions of binding free energies between proteins and small organic ligands would have significant impact on designing drugs @xcite and other modulators of biological processes
. the clear relevance of protein - ligand binding affinity prediction in chemical biology and drug discovery has inspired a vast array of physics - based methods ( for a broad review , see @xcite ) , each with a different trade - off between computational accuracy and speed .
on one extreme , molecular docking focuses on speed ..
Please generate the next two sentences of the article | docking algorithms are designed to quickly obtain plausible configurations of a protein - ligand complex .
scoring functions are then used to rank one configuration versus another . |
8,207 | Suppose that you have an abstract for a scientific paper: we consider the problem of classifying documents not by topic , but by overall sentiment , e.g. , determining whether a review is positive or negative . using movie reviews as data , we find that standard machine learning techniques definitively outperform human - produced baselines
. however , the three machine learning methods we employed ( naive bayes , maximum entropy classification , and support vector machines ) do not perform as well on sentiment classification as on traditional topic - based categorization .
we conclude by examining factors that make the sentiment classification problem more challenging . .
And you have already written the first three sentences of the full article: today , very large amounts of information are available in on - line documents . as part of the effort to better organize this information for users , researchers have been actively investigating the problem of automatic text categorization .
the bulk of such work has focused on _ topical _ categorization , attempting to sort documents according to their subject matter ( e.g. , sports vs. politics ) .
however , recent years have seen rapid growth in on - line discussion groups and review sites ( e.g. , the new york times books web page ) where a crucial characteristic of the posted articles is their _ sentiment _ , or overall opinion towards the subject matter for example , whether a product review is positive or negative ..
Please generate the next two sentences of the article | labeling these articles with their sentimentwould provide succinct summaries to readers ; indeed , these labels are part of the appeal and value - add of such sites as www.rottentomatoes.com , which both labels movie reviews that do not contain explicit rating indicators and normalizes the different rating schemes that individual reviewers use .
sentimentclassification would also be helpful in business intelligence applications ( e.g. mindfuleye s lexant system ) and recommender systems ( e.g. , , ) , where user input and feedback could be quickly summarized ; indeed , in general , free - form survey responses given in natural language format could be processed using sentimentcategorization . |
8,208 | Suppose that you have an abstract for a scientific paper: we study the cauchy problem for the sine - gordon equation in the semiclassical limit with pure - impulse initial data of sufficient strength to generate both high - frequency rotational motion near the peak of the impulse profile and also high - frequency librational motion in the tails .
subject to suitable conditions of a general nature , we analyze the fluxon condensate solution approximating the given initial data for small time near points where the initial data crosses the separatrix of the phase portrait of the simple pendulum .
we show that the solution is locally constructed as a universal curvilinear grid of superluminal kinks and grazing collisions thereof , with the grid curves being determined from rational solutions of the painlev - ii system . .
And you have already written the first three sentences of the full article: this paper is concerned with a detailed local analysis of the solution of the cauchy initial - value problem for the sine - gordon equation @xmath0 we will consider the number @xmath1 to be a small parameter . this type of scaling can be physically motivated in the situation that the sine - gordon equation is used to model the propagation of magnetic flux along superconducting josephson junctions @xcite .
the sine - gordon equation can also be derived in the continuum limit as a model for an array of coaxial pendula with nearest - neighbor torsion coupling @xcite .
this latter application is particularly useful for the purposes of visualization of solutions ..
Please generate the next two sentences of the article | a dramatic separation of scales occurs in the _ semiclassical limit _
@xmath2 if the initial data @xmath3 and @xmath4 are held fixed . |
8,209 | Suppose that you have an abstract for a scientific paper: sn 2003dh , one of the most luminous supernovae ever recorded , and the one with the highest measured velocities , accompanied gamma - ray burst 030329 .
its rapid rise to maximum and equally rapid decline pose problems for any spherically symmetric model .
we model the supernova here as a very energetic , polar explosion that left the equatorial portions of the star almost intact .
the total progenitor mass was much greater than the mass of high - velocity ejecta , and the total mass of @xmath0 synthesized was about 0.5 solar masses .
such asymmetries and nickel masses are expected in the collapsar model .
a `` composite two - dimensional '' model is calculated that agrees well with the characteristics of the observed light curve .
the mass of @xmath0 required for this light curve is @xmath1 and the total explosion energy , @xmath2 . .
And you have already written the first three sentences of the full article: on march 29 , 2003 one of the brightest gamma - ray bursts ( grbs ) in history was discovered and localized by the hete-2 satellite .
astronomers worldwide watched and within days were rewarded by the discovery of a type ic supernova , sn 2003dh , in precisely the same location @xcite . from the light curve and spectrum , a temporal coincidence with the burst
was also estimated to be @xmath3 days ..
Please generate the next two sentences of the article | it is now generally agreed that the supernova and the grb came from the same explosion .
the v - band light curve and spectrum of sn 2003dh closely resembled that of another famous supernova - grb pair , sn 1998bw @xcite and grb 980425 , but with several important distinctions : * 1 ) * grb 980425 had an observed equivalent isotropic energy in gamma - rays roughly four orders of magnitude less than grb 030329 ; * 2 ) * sn 2003dh rose to maximum in less than 10 days , sn 1998bw took 16 days @xcite ; * 3 ) * sn 2003dh exhibited higher expansion speeds , up to @xmath4 ; and * 4 ) * the total energy of ejected relativistic matter in sn 1998bw was @xmath5 with @xmath6 @xcite . |
8,210 | Suppose that you have an abstract for a scientific paper: we report on the evolution over the last @xmath09 gyr of cosmic history ( i.e. , since @xmath1 ) of late - type galaxy populations in the deep field - north and extended deep field - south ( and , respectively ; jointly cdfs ) survey fields .
our late - type galaxy sample consists of 2568 galaxies , which were identified using rest - frame optical colors and morphologies .
we utilized stacking analyses to investigate the emission from these galaxies , emphasizing the contributions from normal galaxies that are not dominated by active galactic nuclei ( agns ) . over this redshift range
, we find significant increases ( factors of @xmath0510 ) in the mean luminosity ratio ( /@xmath2 ) and the mean ratio ( /@xmath3 ) for galaxy populations selected by @xmath2 and @xmath3 , respectively . when analyzing galaxy samples selected via sfr , we find that the mean ratio ( @xmath4/sfr ) is consistent with being constant over the entire redshift range for galaxies with , thus demonstrating that emission can be used as a robust indicator of star - formation activity out to @xmath5 .
we find that the star - formation activity ( as traced by luminosity ) per unit stellar mass in a given redshift bin increases with decreasing stellar mass over the redshift range , which is consistent with previous studies of how star - formation activity depends on stellar mass .
finally , we extend our analyses to lyman break galaxies at @xmath6 and estimate that /@xmath2 at @xmath6 is similar to its value at @xmath1 . .
And you have already written the first three sentences of the full article: investigations focusing on global changes in star - formation activity and stellar - mass build - up in field galaxies have provided significant insight into the physical evolution of galaxies and their constituent stellar populations .
it has now been well - established that the global star - formation rate density has declined by roughly an order of magnitude since @xmath7 11.5 ( e.g. , lilly 1996 ; madau 1996 ; steidel 1999 ; hopkins 2004 ; prez - gonzlez 2005 ; schiminovich 2005 ; colbert 2006 ) .
recent investigations into the details of this evolution have shown that the star - formation history of a given galaxy depends strongly on its stellar mass ( e.g. , cowie 1996 ; juneau 2005 ; bundy 2006 ; noeske 2007a , b ; zheng 2007 ) ; the peak star - formation epoch for the most massive galaxies occured earlier in cosmic history than it did for galaxies with lower masses ..
Please generate the next two sentences of the article | x - ray studies of normal late - type galaxies ( i.e. , those that are not dominated by luminous active galactic nuclei [ agns ] ) have shown that emission provides a useful , relatively - unobscured measure of star - formation activity ( e.g. , bauer 2002a ; cohen 2003 ; ranalli 2003 ; colbert 2004 ; grimm 2003 ; gilfanov 2004a ; persic 2004 ; persic & rephaeli 2007 ; however , see barger 2007 ) . in normal galaxies ,
emission originates from binaries , supernovae , supernova remnants , hot ( @xmath0 ) interstellar gas , and o - stars ( see , e.g. , fabbiano 1989 , 2006 for reviews ) . |
8,211 | Suppose that you have an abstract for a scientific paper: the bizarre behaviour of the apparent ( black hole and cosmological ) horizons of the mcvittie spacetime is discussed using , as an analogy , the schwarzschild - de sitter - kottler spacetime ( which is a special case of mcvittie anyway ) . for a dust - dominated `` background '' universe ,
a black hole can not exist at early times because its ( apparent ) horizon would be larger than the cosmological ( apparent ) horizon .
a phantom - dominated `` background '' universe causes this situation , and the horizon behaviour , to be time - reversed . .
And you have already written the first three sentences of the full article: cosmology and black holes as seen through the eyes of general relativity come together in the investigation of a dynamical black hole embedded in a cosmological background .
the interplay between the cosmic dynamics and the black hole gives rise to interesting phenomena and can reveal some unexpected features of the underlying theory of gravity . in this work
we restrict our attention , for simplicity , to spherically symmetric systems ..
Please generate the next two sentences of the article | the prototypical solution of the einstein equations representing a black hole embedded in a cosmological spacetime is the schwarzschild - de sitter - kottler solution
. this metric is special since it admits a timelike killing vector and is , therefore , static in the region between the black hole horizon and the de sitter ( cosmological ) horizon . |
8,212 | Suppose that you have an abstract for a scientific paper: we address the dynamics of adsorbed molecules ( a fundamental issue in surface physics ) within the framework of a master equation scheme , and study the diffusion of particles in a finite cubic lattice whose boundaries are at the @xmath0 and the @xmath1 planes where @xmath2 , while the @xmath3 and @xmath4 directions are unbounded .
as we are interested in the effective diffusion process at the interface @xmath5 , we calculate analytically the conditional probability for finding the system on the @xmath0 plane as well as the surface dispersion as a function of time and compare these results with monte carlo simulations finding an excellent agreement . .
And you have already written the first three sentences of the full article: the dynamics of adsorbed molecules is a fundamental issue in interface science @xcite and is also crucial in a large number of emerging technologies @xcite .
adsorption at the solid - liquid interfaces arises , for instance , in many biological contexts involving protein deposition @xcite , in solutions or melts of synthetic macromolecules @xcite , in colloidal dispersions @xcite , and in the manufacture of self - assembly mono- and multi - layers @xcite .
experimental studies of surfactant molecules @xcite , proteins @xcite and synthetic polymers @xcite confined to interfaces have identified different types of surface translational motions ..
Please generate the next two sentences of the article | one is in - surface self - diffusion of individual molecules , which has been investigated with fluorescence recovery after photobleaching ( frap ) methods @xcite .
measured self - diffusivity at liquid - solid interfaces are much smaller than bulk values @xcite and similar to bulk values in liquid - gas cases @xcite . |
8,213 | Suppose that you have an abstract for a scientific paper: we construct most symmetric saddle towers in heisenberg space i.e. periodic minimal surfaces that can be seen as the desingularization of vertical planes intersecting equiangularly .
the key point is the construction of a suitable barrier to ensure the convergence of a family of bounded minimal disks .
such a barrier is actually a periodic deformation of a minimal plane with prescribed asymptotic behavior .
a consequence of the barrier construction is that the number of disjoint minimal graphs suppoerted on domains is not bounded in heisenberg space .
_ mathematics subject classification : _ _ 53a10 , 53c42_. .
And you have already written the first three sentences of the full article: the study of periodic surfaces has recently encountered new developments in homogeneous @xmath0-spaces . in @xmath1 ,
new examples have been constructed such as for instance doubly periodic minimal surfaces by mazet , rodrguez and rosenberg @xcite or genus one constant mean curvature @xmath2 surfaces by plehnert @xcite .
other examples are involved in important results such as the resolution of alexandrov problem in a quotient space of @xmath1 by menezes @xcite or the fact the calabi - yau conjectures do not hold for embedded minimal surface in @xmath1 by rodrguez and tinaglia @xcite . in heisenberg space ,.
Please generate the next two sentences of the article | new examples are mostly of scherk type like the jenkins - serrin theorem for compact domains obtained by pinheiro @xcite . the present paper deals with the construction of another kind of scherk type surfaces , called _ most symmetric saddle towers _ , in heisenberg space .
a saddle tower is a minimal surface that can be thought of as the desingularization of @xmath3 vertical planes , @xmath4 , intersecting along a vertical geodesic ; in particular it is a complete embedded minimal surface with @xmath5 planar ends . |
8,214 | Suppose that you have an abstract for a scientific paper: we report a preliminary measurement of the mixing parameter @xmath0 and the cp - violating parameter using the decay @xmath1 followed by @xmath2 and @xmath3 .
the results are obtained from a @xmath4 data sample collected near the @xmath5 resonance with the belle detector at the kekb asymmetric energy @xmath6 collider . .
And you have already written the first three sentences of the full article: the rate of mixing , which has not yet been observed , would provide an important window on new physics .
the contribution of box diagrams is very small due to gim suppression , and the mixing rate is believed to be dominated by long - distance processes .
these processes are themselves suppressed by @xmath7-flavor symmetry ..
Please generate the next two sentences of the article | the mixing rate is usually expressed in terms of the parameters @xmath8 and @xmath9 , where @xmath10 and @xmath11 are the mass- and width - differences of the physical states , and @xmath12 is the average decay width .
numerous predictions for @xmath13 and @xmath14 exist @xcite ; a recent calculation gives @xmath15 @xcite . |
8,215 | Suppose that you have an abstract for a scientific paper: we propose a scheme for implementing the cnot gate over qubits encoded in a pair of electron spins in a double quantum dot .
the scheme is based on exchange and spin orbit interactions and on local gradients in zeeman fields .
we find that the optimal device geometry for this implementation involves effective magnetic fields that are parallel to the symmetry axis of the spin orbit interaction .
we show that the switching times for the cnot gate can be as fast as a few nanoseconds for realistic parameter values in gaas semiconductors .
guided by recent advances in surface codes , we also consider the perpendicular geometry . in this case ,
leakage errors due to spin orbit interaction occur but can be suppressed in strong magnetic fields . .
And you have already written the first three sentences of the full article: standard quantum computing @xcite is based on encoding , manipulating , and measuring quantum information encoded in the state of a collection of quantum two - level systems - qubits .
spin-@xmath0 is an ideal implementation of a qubit , since it is a natural two - level system , and every pure state of a spin-@xmath0 corresponds to a state of a qubit .
for this reason , spins have been considered as carriers of quantum information in a variety of proposals @xcite . the initial proposal @xcite called for spins in single - electron quantum dots electrically manipulated by the exchange interaction and local time - dependent zeeman fields . a variety of other encoding schemes and manipulation techniques @xcite rely upon encoded qubits . in these schemes ,.
Please generate the next two sentences of the article | the simplicity of qubit states and minimal number of physical carriers of quantum information are traded for less stringent requirements for experimental implementations . on one hand ,
the alternative setups protect from the most common types of errors by decoupling the computational degrees of freedom from the most common sources of noise , and therefore allow for longer gating times . on the other hand , in some alternative setups |
8,216 | Suppose that you have an abstract for a scientific paper: properties of systems driven by white non - gaussian noises can be very different from these of systems driven by the white gaussian noise .
we investigate stationary probability densities for systems driven by @xmath0-stable lvy type noises , which provide natural extension to the gaussian noise having however a new property mainly a possibility of being asymmetric .
stationary probability densities are examined for a particle moving in parabolic , quartic and in generic double well potential models subjected to the action of @xmath0-stable noises .
relevant solutions are constructed by methods of stochastic dynamics . in situations
where analytical results are known they are compared with numerical results .
furthermore , the problem of estimation of the parameters of stationary densities is investigated . .
And you have already written the first three sentences of the full article: behavior of many natural systems in contact with their surroundings can be described within a stochastic picture based on langevin equations .
the basic equation of this type reads @xmath1 where @xmath2 is the deterministic `` force '' representing the internal dynamics of the system and @xmath3 is the `` noise '' describing its interaction with its complex surrounding ( heat bath ) . in many cases
this noise can be considered as white and gaussian , giving rise to the classical langevin approach used in the analysis of brownian motion ..
Please generate the next two sentences of the article | the whiteness of the noise ( lack of temporal correlations ) corresponds to the existence of time - scale separation between the dynamics of a relevant variable of interest @xmath4 and the typical timescale of the noise .
white noise can be thus considered as a standard stochastic process that describes in the simplest fashion the effects of `` fast '' surrounding . on the other hand , the gaussian nature of the noise |
8,217 | Suppose that you have an abstract for a scientific paper: we investigate multiple fano , comblike scattering resonances in single - layered , concentric core - shell nanoparticles composed of magnetic materials . using the lorenz - mie theory , we derive , in the long - wavelength limit , an analytical condition for the occurrence of comblike resonances in the single scattering by coated spheres .
this condition establishes that comblike scattering response uniquely depends on material parameters and thickness of the shell , provided that it is magnetic and thin compared to the scatterer radius .
we also demonstrate that comblike scattering response shows up beyond the long - wavelength limit and it is robust against absorption .
since multiple fano resonances are shown to depend explicitly on the magnetic permeability of the shell , we argue that both the position and profile of the comblike , morphology - dependent resonances could be externally tuned by exploiting the properties of engineered magnetic materials . .
And you have already written the first three sentences of the full article: optical systems exhibiting comblike resonances have a wide range of scientific and technological applications , especially in spectroscopy and frequency metrology @xcite .
comblike profiles , which consist of ultrasharp resonance peaks , can be achieved _
e.g. _ in the electromagnetic ( em ) scattering by plasmonic nanoparticles or via morphology - dependent resonances in nonmetallic scatterers . indeed ,.
Please generate the next two sentences of the article | plasmonic nanoparticles support localized surface plasmon resonances that are strongly dependent on their geometrical and material parameters , allowing for engineering the scattering response @xcite .
in addition , scatterers with a high degree of symmetry , such as spheres , spheroids and cylinders , may support morphology - dependent resonances , which are related to constructive interferences confined inside the particle by almost total internal reflections @xcite . |
8,218 | Suppose that you have an abstract for a scientific paper: for the period july 2003 to august 2010 , the interplanetary coronal mass ejection ( icme ) catalogue maintained by richardson and cane lists 106 earth - directed events , which have been measured in - situ by plasma and field instruments on board the ace satellite .
we present a statistical investigation of the earth s thermospheric neutral density response by means of accelerometer measurements collected by the grace satellites , which are available for 104 icmes in the data set , and its relation to various geomagnetic indices and characteristic icme parameters such as the impact speed ( @xmath0 ) , southward magnetic field strength ( @xmath1 ) .
the majority of icmes causes a distinct density enhancement in the thermosphere , with up to a factor of eight compared to the pre event level .
we find high correlations between icme @xmath1 and thermospheric density enhancements ( @xmath2 ) , while the correlation with the icme impact speed is somewhat smaller ( @xmath3 ) .
the geomagnetic indices revealing the highest correlations are dst and sym - h ( @xmath2 ) , the lowest correlations are obtained for @xmath4 and ae ( @xmath3 ) , which show a nonlinear relation with the thermospheric density enhancements .
separating the response for the shock sheath region and the magnetic structure of the icme , we find that the dst and sym - h reveal a tighter relation to the @xmath1 minimum in the magnetic structure of the icme , whereas the polar cap indices show higher correlations with the @xmath1 minimum in the shock sheath region .
since the strength of the @xmath1 component either in the sheath or the magnetic structure of the icme is highly correlated ( @xmath2 ) with the neutral density enhancement , we discuss the possibility of satellite orbital decay estimates based on magnetic field measurements at l1 , i.e. before the icme hits the earth magnetosphere .
these results are expected to further stimulate progress in space weather understanding and applications regarding satellite operations . .
And you have already written the first three sentences of the full article: since the beginning of the space age in the late 1950 s , `` space weather '' is a hot topic .
it deals with the space environment of the earth s atmosphere from approximately 90 km altitude onwards extending all the way to the sun .
strong disturbances of this space environment are primarily caused by solar flares , coronal mass ejections ( cmes ) and associated solar energetic particles ( seps ) ..
Please generate the next two sentences of the article | owing to advances in solar research in the recent decades , today we know that cmes cause the most comprehensive spectrum of space weather disturbances , including geomagnetic storms , aurorae , geomagnetically induced currents affecting electric power lines , heating of the outer atmosphere , and many more .
cmes are huge clouds of magnetized plasma propagating from the solar corona into interplanetary space with speeds ranging from a few hundred up to @xmath53000 km s@xmath6 . |
8,219 | Suppose that you have an abstract for a scientific paper: a novel decoding algorithm is developed for general quantum convolutional codes . exploiting useful ideas from classical coding theory , the new decoder introduces two innovations that drastically reduce the decoding complexity compared to the existing quantum viterbi decoder .
first , the new decoder uses an efficient linear - circuits - based mechanism to map a syndrome to a candidate vector , whereas the existing algorithm relies on a non - trivial lookup table .
second , the new algorithm is cleverly engineered such that only one run of the viterbi algorithm suffices to locate the most - likely error pattern , whereas the existing algorithm must run the viterbi algorithm many times .
the efficiency of the proposed algorithm allows us to simulate and present the first performance curve of a general quantum convolutional code . .
And you have already written the first three sentences of the full article: we consider quantum error correction coding ( qecc ) models where quantum bits ( qubits ) and quantum errors are both modeled as linear combination of pauli matrices @xmath0 .
an [ @xmath1 ( block ) stabilizer code to denote quantum stabilizer codes , ( ... ) to denote classical binary codes , and ( ... ) @xmath2 to denote classical quaternary codes . ] is defined as a codeword space @xmath3 which is _ non - trivially _ stabilized by a subgroup @xmath4 of @xmath5 , where @xmath5 is length-@xmath6 tensor product of pauli - operators @xmath7 , @xmath8 , @xmath9 , @xmath10 . by definition , the independent generators of @xmath4 commute to each other , and @xmath11 .
the dichotomy between the unobservable state of a qubit and the observations we can make , lies at the heart of quantum computation including qecc . in classic error correction ,.
Please generate the next two sentences of the article | output from the channel is observed , measured and used directly in the decoding process .
observation in quantum mechanics not only destroys the quantum state and makes restoration impossible , but the measurement does not tell the original quantum state either . the measured outcome is always one of the two basic states , |
8,220 | Suppose that you have an abstract for a scientific paper: recent x - ray study of middle - aged supernova remnants ( snrs ) reveals strong radiative recombination continua ( rrcs ) associated with overionized plasmas , of which the origin still remains uncertain .
we report our discovery of an rrc in the middle - aged snr 3c 391 . if the x - ray spectrum is fitted with a two - temperature plasma model in collisional ionization equilibrium ( cie ) , residuals of si ly@xmath0 line at 2.006 kev , s ly@xmath0 line at 2.623 kev and the edge of rrc of si at 2.666 kev are found .
the x - ray spectrum is better described by a composite model consisting of a cie plasma and a recombining plasma ( rp ) .
the abundance pattern suggests that the rp is associated to the ejecta from a core - collapse supernova with a 15 progenitor mass .
there is no significant difference of the recombining plasma parameters between the southeast region and the northwest region surrounded by dense molecular clouds .
we also find a hint of fe k@xmath0 line at 6.4 kev ( @xmath1 detection ) from the southeast region of the snr . .
And you have already written the first three sentences of the full article: the standard picture of thermal plasmas associated with supernova remnants ( snrs ) is that the state of the gas appears to be either an ionizing plasma ( ip ) for young or intermediate aged snrs ( e.g. kepler s snr , kinugasa and tsunemi 1999 ) , or plasma in collisional ionization equilibrium ( cie ) for old snrs ( e.g. 30 dor c , yamaguchi et al . 2009 ) .
however , recent x - ray observations have revealed several snrs are in recombination - dominated phase ( ic 443 , yamaguchi 2009 ; w49b , ozawa 2009 ; [email protected] , ohnishi 2011 ; w28 , sawada & koyama 2012 ; w44 , uchida 2012 ; [email protected] , yamauchi 2013 ) .
these recombining plasmas ( rps ) have an ionization temperature ( @xmath3 ) higher than the electron temperature ( @xmath4 ) ; @xmath3 is a useful parameter defined to be the temperature which would be required to ionize the plasma to the same degree assuming that the plasma is in cie ..
Please generate the next two sentences of the article | the discovery of rps at snrs requires us to modify the conventional evolution scenario of snrs .
3c 391 ( g31.9 + 0.0 ) is a bright galactic snr displaying diffuse x - ray emission close the center of its radio shell and is classified as a mixed - morphology snr ( mm - snr ) ( reynolds & moffett 1993 ) . |
8,221 | Suppose that you have an abstract for a scientific paper: we briefly review how nonrelativistic effective field theories give us a definition of the qcd potentials and a coherent field theory derived quantum mechanical scheme to calculate the properties of bound states made by two or more heavy quarks . in this framework
heavy quarkonium properties depend only on the qcd parameters ( quark masses and @xmath0 ) and nonpotential corrections are systematically accounted for .
the relation between the form of the nonperturbative potentials and the low energy qcd dynamics is also discussed . _ em _ .
And you have already written the first three sentences of the full article: hadron properties should be obtained from the qcd lagrangian as a function of the coupling constant @xmath0 and of the quark masses @xmath1 . in practice ,
things are made complicate by qcd being a strongly coupled theory in the low energy region . at the scale @xmath2 ,
nonperturbative effects become dominant and @xmath0 becomes large ..
Please generate the next two sentences of the article | the nonperturbative qcd dynamics originates the confinement of quarks inside hadrons .
typical approaches include , on one hand the use of phenomenological potential models and constituent quark model descriptions , on the other hand first principles lattice simulations ( still far from the physical parameter window in many cases ) . |
8,222 | Suppose that you have an abstract for a scientific paper: improved potential solutions are presented for the inverse scattering problem for @xmath0+@xmath1he data .
the input for the inversions includes both the data of recent phase shift analyses and phase shifts from rgm coupled - channel calculations based on the nn minnesota force .
the combined calculations provide a more reliable estimate of the odd - even splitting of the potentials than previously found , suggesting a rather moderate role for this splitting in deuteron - nucleus scattering generally .
the approximate parity - independence of the deuteron optical potentials is shown to arise from the nontrivial interference between antisymmetrization and channel coupling to the deuteron breakup channels .
a further comparison of the empirical potentials established here and the double folding potential derived from the m3y effective nn force ( with the appropriate normalisation factor ) reveals strong similarities .
this result supports the application of the double folding model , combined with a small majorana component , to the description even of such a loosely bound projectile as the deuteron . in turn
, support is given for the application of iterative - perturbative inversion in combination with the double folding model to study fine details of the nucleus - nucleus potential .
a @xmath0-@xmath1he tensor potential is also derived to reproduce correctly the negative @xmath2li quadrupole moment and the @xmath3-state asymptotic constant .
= msam10 contents of the paper . 1 .
introduction 2 .
the role of parity dependence in ip inversion 3 .
stabilised inversion of the @xmath0-@xmath1he empirical data for @xmath415 mev 4 .
inversion of rgm @xmath5 with breakup channel contributions 5 .
validity of double folding model for @xmath0-@xmath1he interaction and similar systems
. 6 .
tensor @xmath0-@xmath1he potential and the @xmath6-quadrupole moment . 7
. conclusions .
And you have already written the first three sentences of the full article: many basic features of the interactions between light composite particle are now well established . in particular , a good description @xcite-@xcite , of the interactions of light nuclei such as @xmath7 , @xmath8+@xmath9he , @xmath1he+@xmath1he etc .
is obtained from a deep attractive potential with pauli - forbidden states with the addition of parity dependence , young scheme splitting and a spin - orbit interaction .
importantly , this type of interaction is now justified from microscopic considerations , both in quasi - classic picture @xcite and also in quantum mechanical shell - model framework @xcite ..
Please generate the next two sentences of the article | these results lead to a general comprehensive understanding of the relations between various interaction models which appear , at a first glance , to contradict to each other .
nevertheless , a number of finer features of the interaction , notably the role of the dynamic polarisation of loosely bound projectiles such as @xmath0 or @xmath10li when combined with antisymmetrization effects , are not yet fully understood despite many previous efforts . |
8,223 | Suppose that you have an abstract for a scientific paper: the lifetime of solar - like stars , the envelope structure of more massive stars , and stellar acoustic frequencies largely depend on the radiative properties of the stellar plasma . up to now , these complex quantities have been estimated only theoretically .
the development of the powerful tools of helio- and astero- seismology has made it possible to gain insights on the interiors of stars .
consequently , increased emphasis is now placed on knowledge of the monochromatic opacity coefficients . here
we review how these radiative properties play a role , and where they are most important .
we then concentrate specifically on the envelopes of @xmath0 cephei variable stars .
we discuss the dispersion of eight different theoretical estimates of the monochromatic opacity spectrum and the challenges we need to face to check these calculations experimentally .
* published in astrophysics and space science * .
And you have already written the first three sentences of the full article: after more than two decades of study , helioseismology has demonstrated the capability to probe the solar interior thanks to the seismic instruments of the soho satellite and ground - based networks @xcite . the new space missions ( sdo , picard ) are oriented toward a better understanding of the sun s internal magnetism and its impact on the earth s atmosphere . in this context , the existence of a fossil field in the sun s radiative zone is a missing bridge that motivate us to better estimate the competition between microscopic and macroscopic physics @xcite .
in addition to the international solar research community , more than 350 scientists from all over the world are working on the data from the corot and kepler spacecraft dedicated to exoplanets and astero - seismology ( see http://smsc.cnes.fr/corot for corot and http://astro.phys.au.dk/kasc/ for kepler ) .
the development of these disciplines justifies ensuring the correctness of the many fundamental properties of the plasma ( detailed abundances , reaction rates , opacity coefficients , etc . ) . the new high energy density laser facilities and the z pinch machine now enable access to the radiative properties of plasmas of stellar type in the laboratory during pico and nano second timescales ;.
Please generate the next two sentences of the article | see @xcite , and references therein .
this review is divided into three parts : section 2 is dedicated to solar - type stars , section 3 to the more massive stars , and section 4 to the study of the @xmath0 cephei variable star case and a comparison between eight calculated iron opacity spectra . |
8,224 | Suppose that you have an abstract for a scientific paper: this paper studies the capacity of the peak - and - average - power - limited gaussian channel when its output is quantized using a dithered , infinite - level , uniform quantizer of step size @xmath0 .
it is shown that the capacity of this channel tends to that of the unquantized gaussian channel when @xmath0 tends to zero , and it tends to zero when @xmath0 tends to infinity . in the low signal - to - noise ratio ( snr ) regime , it is shown
that , when the peak - power constraint is absent , the low - snr asymptotic capacity is equal to that of the unquantized channel irrespective of @xmath0 .
furthermore , an expression for the low - snr asymptotic capacity for finite peak - to - average - power ratios is given and evaluated in the low- and high - resolution limit .
it is demonstrated that , in this case , the low - snr asymptotic capacity converges to that of the unquantized channel when @xmath0 tends to zero , and it tends to zero when @xmath0 tends to infinity . comparing these results with achievability results for ( undithered ) 1-bit quantization , it is observed that the dither reduces capacity in the low - precision limit , and it reduces the low - snr asymptotic capacity unless the peak - to - average - power ratio is unbounded .
[ multiblock footnote omitted ] .
And you have already written the first three sentences of the full article: we study the capacity of the discrete - time , peak - and - average - power - limited , gaussian channel when its output is quantized using a dithered , infinite - level , uniform quantizer of step size @xmath0 and analyze its behavior in the low- and high - precision limit , where @xmath0 tends to infinity and zero , respectively .
the problem of quantization arises in communication systems where the receiver uses digital signal processing techniques , so the analog received signal must be sampled and then quantized using an analog - to - digital converter ( adc ) .
if the received signal is sampled at nyquist rate or above , and if an adc with high precision is employed , then the effects of sampling and quantization are negligible.
Please generate the next two sentences of the article | . however , high - precision adcs may not be practical when the bandwidth of the system is large and the sampling - rate is high @xcite . in such scenarios , low - resolution adcs must be used . to better understand what communication rates can be achieved with
low - resolution adcs and nyquist sampling , various works have studied the discrete - time gaussian channel when its output is quantized using a 1-bit quantizer . at low signal - to - noise ratio ( snr ) , where communication at low spectral efficiencies takes place , it is known that a symmetric threshold quantizer if its input is above a threshold , and it produces @xmath1 if its not . a _ symmetric _ |
8,225 | Suppose that you have an abstract for a scientific paper: calculations of sensitivities of future experiments are a necessary ingredient in experimental high energy physics . especially in the context of measurements of the neutrino oscillation parameters extensive studies
are performed to arrive at the optimal configuration . in this note
we clarify the definition of sensitivity as often applied in these studies .
in addition we examine two of the most common methods to calculate sensitivity from a statistical perspective using a toy model .
the importance of inclusion of uncertainties in nuisance parameters for the interpretation of sensitivity calculations is pointed out .
sensitivity , statistical methods , neutrino oscillation experiments .
And you have already written the first three sentences of the full article: in the process of developing experiments measuring new phenomena in physics the estimation of the sensitivity of certain configurations of experiments is of utmost importance . + a particularly active field
is the estimate of sensitivities for future neutrino oscillation experiments , see for example @xcite .
the goal of future experiments is often the measurement of a mixing angle ( denoted @xmath0 ) , the probability for a neutrino oscillation taking place being proportional to @xmath1 ..
Please generate the next two sentences of the article | + in sensitivity studies for neutrino oscillation experiments , `` sensitivity '' is often not defined in the same way .
furthermore uncertainties in nuisance parameters ( often sloppily called `` systematic uncertainties '' ) are often ignored ( see for example @xcite ) or included in calculations in an incomplete manner ( see discussion in @xcite ) . |
8,226 | Suppose that you have an abstract for a scientific paper: we present the abundance analyses of three isolated a - type supergiant stars in the dwarf irregular galaxy (= ddo75 ) from high - resolution spectra obtained with ultraviolet - visual echelle spectrograph ( uves ) on the kueyen telescope ( ut2 ) of the eso very large telescope ( vlt ) .
detailed model atmosphere analyses have been used to determine the stellar atmospheric parameters and the elemental abundances of the stars .
the mean iron group abundance was determined from these three stars to be @xmath0\right>=-0.99\pm0.04\pm{\it 0.06}$]=\log(x/{\rm h})-\log(x/{\rm h})_\odot$ ] .
averages of the abundances of the three stars are marked with @xmath1 .
all abundances are given with two uncertainties : first the line - to - line scatter , second in italics the estimate of the systematic error due to uncertainties in the stellar atmospheric parameters . ] .
this is the first determination of the present - day iron group abundances in sextansa .
these three stars now represent the most metal - poor massive stars for which detailed abundance analyses have been carried out .
the mean stellar @xmath2 element abundance was determined from the @xmath2 element magnesium as @xmath3\right>=-1.09\pm0.02\pm{\it 0.19}$ ] .
this is in excellent agreement with the nebular @xmath2 element abundances as determined from oxygen in the regions .
these results are consistent from star - to - star with no significant spatial variations over a length of @xmath4kpc in sextansa .
this supports the nebular abundance studies of dwarf irregular galaxies , where homogeneous oxygen abundances are found throughout , and argues against in situ ( `` on the spot '' ) enrichment .
the @xmath5 abundance ratio is @xmath6\right>=-0.11\pm0.02\pm{\it 0.10}$ ] , which is slightly lower but consistent with the solar ratio .
this is consistent with the results from a - supergiant analyses in other local group dwarf irregular galaxies , ngc6822 and wlm .
the results of near solar [ @xmath2/fe ] ratios in....
And you have already written the first three sentences of the full article: dwarf irregular galaxies ( dirrs ) are low mass , but gas rich galaxies and are found rather isolated and spread throughout the local group . all dirrs display low elemental abundances indicating that only little chemical evolution has taken place over the past 15gyr despite ongoing star formation .
the lack of strong starburst cycles in these isolated objects may be because of little or no merger interaction .
therefore , in the context the cold dark matter scenarios of hierarchical galaxy formation by merger of smaller structures @xcite , dwarf galaxies and in particular the isolated dwarf irregular galaxies could be the purest remnants of the proto - galactic fragments from the early universe ..
Please generate the next two sentences of the article | hence , the dirrs are also one of the possible sources for the damped ly@xmath2 absorption ( dla ) systems as observed in quasar spectra over a large range of redshifts ; see e.g. @xcite for a recent compilation of dla metallicities over @xmath7 .
the dirrs being possible remnants of the early universe might allow us to study early galaxy evolution in great detail in the nearby universe , even in the local group . |
8,227 | Suppose that you have an abstract for a scientific paper: gamma - ray line emission from radioactive decay of @xmath0fe provides constraints on nucleosynthesis in massive stars and supernovae .
we detect the @xmath1-ray lines from @xmath0fe decay at 1173 and 1333 kev using three years of data from the spectrometer spi on board _ integral_. the average flux per line is @xmath2 for the inner galaxy region . deriving the galactic @xmath3al gamma - ray line flux with using the same set of observations and analysis method
, we determine the flux ratio of @xmath4 gamma - rays as @xmath5 .
we discuss the implications of these results for the widely - held hypothesis that @xmath0fe is synthesized in core - collapse supernovae , and also for the closely - related question of the precise origin of @xmath3al in massive stars . .
And you have already written the first three sentences of the full article: the radioactive isotope @xmath0fe is believed to be synthesized through successive neutron captures on fe isotopes ( e.g. , @xmath6fe ) in a neutron - rich environment inside he burning shells in agb stars ( @xmath7fe is stored in white dwarfs and can not be ejected ) and massive stars , before or during their final evolution to core collapse supernovae ( ccsn ) .
@xmath7fe can be also synthesized in type ia sne ( woosley 1997 ) .
it is also destroyed by the @xmath7fe ( @xmath8 ) process . since its closest parent ,.
Please generate the next two sentences of the article | @xmath9fe is unstable , the @xmath9fe(@xmath8 ) process must compete with the @xmath9fe(@xmath10 ) decay to produce an appreciate amount of @xmath7fe .
the decay chains of @xmath7fe are shown in figure 1 . |
8,228 | Suppose that you have an abstract for a scientific paper: multiple loop formation in polymer macromolecules is an important feature of the chromatin organisation and dna compactification in the nuclei .
we analyse the size and shape characteristics of complex polymer structures , containing in general @xmath0 loops ( petals ) and @xmath1 linear chains ( branches ) . within the frames of continuous model of gaussian macromolecule
, we apply the path integration method and obtain the estimates for gyration radius @xmath2 and asphericity @xmath3 of typical conformation as functions of parameters @xmath0 , @xmath1 . in particular ,
our results qualitatively reveal the extent of anisotropy of star - like topologies as compared to the rosette structures of the same total molecular weight . .
And you have already written the first three sentences of the full article: loop formation in macromolecules plays an important role in a number of biochemical processes : stabilisation of globular proteins @xcite , transcriptional regularisation of genes @xcite as well as dna compactification in the nucleus @xcite .
the localisation of chromatin fibres to semi - compact regions known as chromosome territories is maintained among others by the topological constraints introduced by multiple loops in chromatin organisation @xcite .
numerous analytical and numerical studies have been conducted to analyse the cyclisation probability and loop size distributions in long flexible macromolecules @xcite ..
Please generate the next two sentences of the article | the conformational properties of isolated loops ( ring polymers ) @xcite and multiple loops @xcite have been intensively studied as well . interlocking and entanglements are ubiquitous features of flexible polymers of high molecular weight
. in particular , dna can exist in the form of catenated ( bonded ) rings of various complexities @xcite . |
8,229 | Suppose that you have an abstract for a scientific paper: based on the developed quantum microscopic theory , the interaction of weak electromagnetic radiation with dense ultracold atomic clouds is described in detail .
the differential and total cooperative scattering cross sections are calculated for monochromatic radiation as particular examples of application of the general theory .
the angular , spectral , and polarization properties of scattered light are determined .
the dependence of these quantities on the sample size and concentration of atoms is studied and the influence of collective effects is analyzed . .
And you have already written the first three sentences of the full article: a great number of experimental and theoretical papers devoted to the study of cold and ultracold atomic ensembles are related to the unique physical properties inherent in these systems and their broad possible practical applications .
improvements in techniques for cooling atomic gases in atomic traps @xcite make their use very promising in metrology , frequency standards , and quantum information problems @xcite-@xcite .
most of the methods for diagnostics of the states of these ensembles are based on their interaction with electromagnetic radiation ..
Please generate the next two sentences of the article | more importantly , the largest number of the many applications envisioned for ultracold atom ensembles have at their foundation such interactions .
the interaction of radiation with cold atomic clouds reveals a number of specific features . |
8,230 | Suppose that you have an abstract for a scientific paper: direct numerical simulations are conducted for double diffusive convection ( ddc ) bounded by two parallel plates .
the prandtl numbers , i.e. the ratios between the viscosity and the molecular diffusivities of scalars , are similar to the values of seawater . the ddc flow is driven by an unstable salinity difference ( here across the two plates ) and stabilized at the same time by a temperature difference .
for these conditions the flow can be in the finger regime .
we develop scaling laws for three key response parameters of the system : the non - dimensional salinity flux @xmath0 mainly depends on the salinity rayleigh number @xmath1 , which measures the strength of the salinity difference , and exhibits a very weak dependence on the density ratio @xmath2 , which is the ratio of the buoyancy forces induced by two scalar differences .
the non - dimensional flow velocity @xmath3 and the non - dimensional heat flux @xmath4 are dependent on both @xmath1 and @xmath2 .
however , the rescaled reynolds number @xmath5 and the rescaled convective heat flux @xmath6 depend only on @xmath1 .
the two exponents are dependent on the fluid properties and are determined from the numerical results as @xmath7 and @xmath8 . moreover
, the behaviors of @xmath0 and @xmath5 agree with the predictions of the grossmann - lohse theory which was originally developed for the rayleigh - bnard flow .
the non - dimensional salt - finger width and the thickness of the velocity boundary layers , after being rescaled by @xmath9 , collapse and obey a similar power - law scaling relation with @xmath1 .
when @xmath1 is large enough , salt fingers do not extend from one plate to the other and horizontal zonal flows emerge in the bulk region .
we then show that the current scaling strategy can be successfully applied to the experimental results of a heat - copper - ion system ( hage and tilgner , _ phys . fluids _
, * 22 * , 076603 , 2010 ) .
the fluid has different properties and the exponent @xmath10 takes a different....
And you have already written the first three sentences of the full article: double diffusive convection ( ddc ) is the convection flow where fluid density depends on two scalar fields .
one of the most relevant application is oceanic mixing , in which the two scalars are temperature and salinity .
temperature diffuses about 100 times faster than salinity , and this huge difference in the molecular diffusivities allows for very rich dynamics in oceanic ddc flow @xcite ..
Please generate the next two sentences of the article | for instance , an instability can occur even when the fluid is overall stably stratified @xcite .
a comprehensive review of the field can be found in the recent book by @xcite . |
8,231 | Suppose that you have an abstract for a scientific paper: we discuss corrections to @xmath0 , @xmath1 and to the cp violation parameter @xmath2 in two examples of ( generalized ) minimal flavour violation models : 2hdm and mssm in the large @xmath3 limit .
we show that for @xmath4 not too heavy , @xmath5 in the mssm with heavy sparticles can be substantially smaller than in the sm due the charged higgs box contributions and in particular due to the growing like @xmath6 contribution of the double penguin diagrams involving neutral higgs boson exchanges .
hep - ph/0108226 * processes in the mssm in large limit * janusz rosiek _ physik department , technische universitt mnchen , d-85748 garching , germany _ + the determination of the ckm parameters is the hot topic in particle physics . in view of forthcoming precise results from b - factories
, it is particularly important to discuss possible effects of new physics contributions to @xmath7 processes : @xmath0 and @xmath8 mass differences and to the cp violation parameter @xmath2 . in general models of new physics
fall into the two following broad classes : + @xmath9 models in which the ckm matrix remains the unique source of flavour and cp violation - so - called minimal flavour violation ( mfv ) models @xcite and their generalizations ( gmfv models ) . in the gmfv models the non sm - like operators contribute significantly to the effective low energy hamiltonian @xcite .
+ @xmath9 models with entirely new sources of flavour and/or cp violation .
+ on the basis of the analysis @xcite we discuss here two examples of the gmfv models : the large @xmath3 limit of the 2hdm(ii ) and of the mssm , in which the ckm matrix is the only source of flavour and cp violation ( see e.g. @xcite ) .
the effective weak hamiltonian for @xmath7 transitions in the gmvf models can be written as follows [ heff ] h_eff^=2 = g_f^2m_w^216 ^ 2 _ i v^i_ckm c_i ( ) q_i . where @xmath10 are the set of 8 dimension six @xmath7 operators @xcite and @xmath11 are the appropriate ckm factors .
@xmath0,@xmath5 and....
And you have already written the first three sentences of the full article: this work was supported in part by the german bundesministerium fr bildung and forschung under the contract 05ht1woa3 , by the polish state committee for scientific research grant 2 p03b 060 18 for years 2000 - 2001 and by the ec contract hprn - ct-2000 - 00148 for years 2000 - 2004 ..
Please generate the next two sentences of the article | |
8,232 | Suppose that you have an abstract for a scientific paper: the universal density functional @xmath0 of density - functional theory is a complicated and ill - behaved function of the density in particular , @xmath0 is not differentiable , making many formal manipulations more complicated .
whilst @xmath0 has been well characterized in terms of convex analysis as forming a conjugate pair @xmath1 with the ground - state energy @xmath2 via the hohenberg kohn and lieb variation principles , @xmath0 is nondifferentiable and subdifferentiable only on a small ( but dense ) set of its domain . in this article
, we apply a tool from convex analysis , moreau yosida regularization , to construct , for any @xmath3 , pairs of conjugate functionals @xmath4 that converge to @xmath1 pointwise everywhere as @xmath5 , and such that @xmath6 is ( frchet ) differentiable . for technical reasons ,
we limit our attention to molecular electronic systems in a finite but large box .
it is noteworthy that no information is lost in the moreau
yosida regularization : the physical ground - state energy @xmath7 is exactly recoverable from the regularized ground - state energy @xmath8 in a simple way .
all concepts and results pertaining to the original @xmath1 pair have direct counterparts in results for @xmath9 .
the moreau
yosida regularization therefore allows for an exact , differentiable formulation of density - functional theory .
in particular , taking advantage of the differentiability of @xmath10 , a rigorous formulation of kohn sham theory is presented that does not suffer from the noninteracting representability problem in standard kohn sham theory . .
And you have already written the first three sentences of the full article: modern density - functional theory ( dft ) was introduced by hohenberg and kohn in a classic paper @xcite and is now the workhorse of quantum chemistry and other fields of quantum physics .
subsequently , dft was put on a mathematically firm ground by lieb using convex analysis.@xcite the central quantity of dft is the universal density functional @xmath11 , which represents the electronic energy of the system consistent with a given density @xmath12 . clearly , the success of dft hinges on the modelling of @xmath0 , an extremely complicated function of the electron density .
it is an interesting observation that , over the last two or three decades , @xmath0 has been modelled sufficiently accurately to make dft the most widely applied method of quantum chemistry , in spite of the fact that schuch and verstraete @xcite have shown how considerations from the field of computational complexity place fundamental limits on exact dft : if @xmath11 could be found efficiently , all np hard problems would be solvable in polynomial time , which is highly unlikely.@xcite from a mathematical point of view , dft is neatly formulated using convex analysis@xcite : the universal density functional @xmath11 and the ground - state energy @xmath7 are related by a conjugation operation , with the density @xmath12 and external potential @xmath13 being elements of a certain banach space @xmath14 and its dual @xmath15 , respectively ..
Please generate the next two sentences of the article | the functionals @xmath0 and @xmath2 are equivalent in the sense that they contain the same information each can be generated exactly from the other .
the universal density functional @xmath0 is convex and lower semi - continuous but otherwise highly irregular and ill behaved . |
8,233 | Suppose that you have an abstract for a scientific paper: we present the standard model calculation of the optical activity of a neutrino sea .
the idea that intergalactic space is a birefrigent medium for light due to the presence of a neutrino sea has been contemplated for a long time .
some thirty years ago , royer @xcite computed in @xmath0 theory an effect of order @xmath1 . later
, stodolsky noted that due to a theorem of gell - mann @xcite , there can be no such effect with massless neutrinos and a point - like coupling , and his observation was recorded by one of the present authors in a review @xcite . in the early 1980 s data on propagation of radio waves through intergalactic space put a stringent upper bound on possible optical activity of the neutrino sea @xcite and @xcite and this led to renewed estimates for the size of such effect on the assumption of a neutrino magnetic moment , which occur for a massive neutrino @xcite .
more recently @xcite an evaluation was made for a off - mass shell photons within the standard model ( sm ) .
here we note that there is a frequency dependent effect even for real photons and we also comment on the effect for virtual photons ( both within the sm ) .
thus we shall consider three possible effects : a magnetic moment effect , an effect for virtual photons , an effect for real photons .
+ if the neutrino has a magnetic moment , this moment will interact with the magnetic field of an electromagnetic wave : @xmath2 in this equation @xmath3 is the polarization vector of a photon of momenta @xmath4 , while @xmath5 is the neutrino bispinor , and @xmath6 is the neutrino magnetic moment in bohr magnetons @xmath7 .
+ with this interaction ( 1 ) the forward scattering amplitude of a photon of momentum @xmath8 from a neutrino of momentum @xmath9 is equal to @xmath10 this amplitude differs for left - handed and right - handed photons : @xmath11 and gives rise to a nonzero optical activity for a polarizes neutrino gas . + in the standard model the neutrino has no intrinsic magnetic moment ,....
And you have already written the first three sentences of the full article: this research was supported by nserc - canada and by rfbr grants 98 - 02 - 17372 , 98 - 02 - 17453 and 00 - 15 - 96562 .
m.j.levine , nuovo cimento * a48 * ( 1967 ) 67 .
a.v.kuznetsov and n.v.mikheev , physics letters * b299 * ( 1993 ) 367 ..
Please generate the next two sentences of the article | p.p.kronberg , rep .
prog . phys.*57 * ( 1994 ) 325 ; + e.asseo and h.sol , phys . |
8,234 | Suppose that you have an abstract for a scientific paper: we have used the moving cluster method to identify three l dwarfs and one t dwarf in the ursa major / sirius moving group ( age 400 myr ) .
five l dwarfs and two t dwarfs are found to belong to the hyades moving group ( age 625 myr ) .
these l and t dwarfs define 400- and 625- myr empirical isochrones , assuming that they have the same age . moving group membership does not guarantee coevality .
[ firstpage ] stars : kinematics stars : low mass , brown dwarfs open clusters and associations : individual : ursa major open clusters and associations : individual : hyades galaxies : star clusters .
And you have already written the first three sentences of the full article: apart from a brief phase of lithium burning , brown dwarfs cool continuously .
thus any meaningful comparison with theory requires a knowledge of the age of the brown dwarf . for this reason
much effort has been devoted to finding brown dwarfs in clusters whose age is known ..
Please generate the next two sentences of the article | the three closest clusters are the hyades ( d = 46 pc ) , coma ( d = 90 pc ) and the pleiades ( d = 130 pc ) .
the hyades and coma are old clusters with ages of 625 myr @xcite and 500 myr @xcite respectively , and were not thought to have any brown dwarfs . |
8,235 | Suppose that you have an abstract for a scientific paper: decoy - state protocols provide a way to defeat photon - number splitting attacks in quantum cryptography implemented with weak coherent pulses . we point out that previous security analyses of such protocols relied on assumptions about eavesdropping attacks that considered treating each pulse equally and independently .
we give an example to demonstrate that , without such assumptions , the security parameters of previous decoy - state implementations could be worse than the ones claimed .
next we consider more general photon - number splitting attacks , which correlate different pulses , and give an estimation procedure for the number of single photon signals with rigorous security statements .
the impact of our result is that previous analyses of the number of times a decoy - state quantum cryptographic system can be reused before it makes a weak key must be revised .
la - ur 13 - 20168 .
And you have already written the first three sentences of the full article: quantum key distribution ( qkd ) @xcite allows two parties , alice and bob , to establish a common and secret key @xmath0 that is informationally secure ; see @xcite and references therein .
a widely used setup for qkd is the one suggested by bennett and brassard ( bb84 ) @xcite .
bb84 is ideally implemented by preparing and transmitting single - photon pulses ..
Please generate the next two sentences of the article | information can be encoded in the state of one of two conjugate polarization bases , e.g. vertical / horizontal or diagonal / antidiagonal .
only those photons that were prepared by alice and detected by bob in the same basis are useful to build a sifted key , which forms @xmath0 after additional steps of information reconciliation and privacy amplification . |
8,236 | Suppose that you have an abstract for a scientific paper: starting from the orthorhombic magnetically ordered phase , we investigate the effects of uniaxial tensile and compressive stresses along * a * , * b * , and the diagonal * * a**+*b * directions in bafe@xmath0as@xmath0 and cafe@xmath0as@xmath0 in the framework of _ ab initio _ density functional theory ( dft ) and a phenomonological ginzburg - landau model .
while contrary to the application of hydrostatic or @xmath1-axis uniaxial pressure both systems remain in the orthorhombic phase with a pressure - dependent nonzero magnetic moment , we observe a sign - changing jump in the orthorhombicity at a critical uniaxial pressure , accompanied by a reversal of the orbital occupancy and a switch between the ferromagnetic and antiferromagnetic directions .
our ginzburg - landau analysis reveals that this behavior is a direct consequence of the competition between the intrinsic magneto - elastic coupling of the system and the applied compressive stress , which helps the system to overcome the energy barrier between the two possible magneto - elastic ground states .
our results shed light on the mechanisms involved in the detwinning process of an orthorhombic iron - pnictide crystal and on the changes in the magnetic properties of a system under uniaxial stress . .
And you have already written the first three sentences of the full article: since the discovery of high-@xmath2 superconductivity in fe - based materials in 2008 , @xcite an enormous amount of effort has been invested to understand the microscopic behavior of these systems .
iron pnictides and chalcogenides become superconductors either by hole- or electron - doping the systems , by application of external pressure or by a combination of both . in particular , uniaxial pressure is currently being intensively discussed as a possible route towards modifying the structural , magnetic and even superconducting properties of these systems .
a regular sample below its magnetic and structural transition temperatures displays an equal number of opposite twin orthorhombic domains , effectively canceling out its anisotropic properties . to circumvent this issue and obtain a single orthorhombic domain sample ,.
Please generate the next two sentences of the article | uniaxial tensile stress has been widely employed to detwin iron pnictides like bafe@xmath0as@xmath0 and cafe@xmath0as@xmath0 @xcite and unveil its anisotropic properties which have been argued to originate from electronic nematic degrees of freedom .
@xcite theoretically , although it is clear that in the tetragonal phase the applied uniaxial pressure acts as a conjugate field to the orthorhombic order parameter , condensing a single domain , @xcite the nature of the detwinning process deep inside the orthorhombic phase remains an open question , since different mechanisms might be at play such as twin boundary motion or reversal of the order parameter inside the domains . |
8,237 | Suppose that you have an abstract for a scientific paper: we compute @xmath0 , the dynamical mass interior to a radius of @xmath1 kpc , for a set of 809 isolated host galaxies in the 100k data release of the 2df galaxy redshift survey .
the hosts are surrounded by 1556 satellite galaxies , as defined by a set of specific selection criteria .
our mass estimator and host / satellite selection criteria are taken from those used by the sloan digital sky survey ( sdss ) collaboration for an analysis of @xmath0 for sdss galaxies and , overall , our results compare well with theirs . in particular ,
for @xmath2 we find @xmath3 , with a weak tendency for hosts with @xmath4 to have a somewhat higher @xmath5 .
additionally , we investigate @xmath5 for bright ( @xmath6 ) galaxies with elliptical , s0 , and spiral morphologies .
there are 159 hosts in the elliptical / s0 sample and , similar to the full sample , we find @xmath7 for galaxies with @xmath2 , and a weak tendency for intrinsically fainter galaxies to have a somewhat higher @xmath5 . in stark contrast to this , we find the line of sight velocity dispersion for the 243 spiral hosts to be independent of the host luminosity , with a value of @xmath8 km s@xmath9 .
thus , for spiral hosts we find that @xmath10 , where @xmath11 for a @xmath12 spiral is of order @xmath13 . .
And you have already written the first three sentences of the full article: it is generally accepted that large , bright galaxies reside within massive dark matter halos ; however , the radial extent of the halos is not well constrained and , hence , neither is the total mass nor the mass to light ratio of these objects . galaxy
galaxy lensing , in which the halos of foreground galaxies weakly distort the shapes of background galaxies , has recently proven to be a powerful method by which the masses and mass to light ratios of galaxies may be constrained .
galaxy lensing has been detected by a number of different groups ( see , e.g. , the review by brainerd & blandford 2003 and references therein ) and , in particular , the sloan digital sky survey ( sdss ) collaboration has obtained measurements of the galaxy galaxy lensing shear with extremely high statistical significance ( e.g. , fischer et al ..
Please generate the next two sentences of the article | 2000 ; mckay et al .
2001 ) . using weak lensing measurements of the projected mass correlation function , mckay et al.(2001 ) , hereafter sdss01 , found that @xmath14 , the mass of lens galaxies interior to a radius of @xmath1 kpc , scaled roughly linearly with the luminosities of the lens galaxies in all bandpasses except @xmath15 . since the galaxy galaxy lensing shear is small ( @xmath16% in the case of the sdss galaxies ) and is not without its own sources of error ( including the the separation of lenses from sources ) , mckay et al . |
8,238 | Suppose that you have an abstract for a scientific paper: we present recent results on generalized parton distributions from dynamical lattice qcd calculations .
our set of twelve different combinations of couplings and quark masses allows for a preliminary study of the pion mass dependence of the transverse nucleon structure . .
And you have already written the first three sentences of the full article: the investigation of the nucleon structure in the framework of qcd is a major task in today s particle physics .
generalized parton distributions ( gpds ) have opened new ways of studying the complex interplay of longitudinal momentum and transverse coordinate space as well as spin and orbital angular momentum degrees of freedom in the nucleon .
the twist-2 gpds @xmath0 , @xmath1 , @xmath2 and @xmath3 of quarks in the nucleon are defined by the following parameterization of off - forward nucleon matrix elements @xmath4 for the helicity independent vector case , and @xmath5 for the helicity dependent axial vector case @xcite ..
Please generate the next two sentences of the article | wilson lines ensuring gauge invariance of the bilocal operators are denoted by @xmath6 . here and
in the following we do not show explicitly the dependence of the gpds on the resolution scale @xmath7 . |
8,239 | Suppose that you have an abstract for a scientific paper: in a contact density chain - growth study we investigate the solubility - temperature pseudo - phase diagram of a lattice polymer in a cavity with an attractive surface .
in addition to the main phases of adsorbed and desorbed conformations we find numerous subphases of collapsed and expanded structures . .
And you have already written the first three sentences of the full article: the requirement of higher integration scales in electronic circuits , the onset of nanosensory applications in biomedicine , but also the fascinating capabilities of modern experimental setup with its enormous potential in polymer and surface research recently led to an increasing interest at the hybrid interface of organic and inorganic matter @xcite .
this also includes numerous detailed studies , e.g. , of polymer film wetting phenomena @xcite , pattern recognition @xcite , protein ligand binding and docking @xcite , charged adsorbed polymers @xcite as well as deposition and growth of polymers at surfaces @xcite . in most theoretical and computational studies
the polymer is anchored at the substrate with one of its ends which reduces the entropic freedom of the polymer ..
Please generate the next two sentences of the article | these surface - grafted polymers @xcite are , e.g. , of particular interest in studies of shape transformations @xcite , e.g. , as reaction to external fields @xcite . however , in many recent experiments of organic inorganic interfaces the setup is different @xcite and is more adequately described by a polymer moving in a cavity with one adsorbing surface @xcite .
the main difference of such nongrafted polymers considered in this work is of entropic kind : in the desorbed phase the polymer can move freely within the cavity , and the polymer can fold into conformations , where the ends have no contact with the surface . |
8,240 | Suppose that you have an abstract for a scientific paper: under the thomas - fermi approximation , a relatively much simpler analytical solutions of the coupled gross - pitaevskii equations for the two - species bec have been derived .
additionally , a model for the asymmetric states has been proposed , and the competition between the symmetric and asymmetric states has been evaluated .
the whole parameter - space is divided into zones , each supports a specific phase , namely , the symmetric miscible phase , the symmetric immiscible phase , or the asymmetric phase . based on the division the phase - diagrams against any set of parameters can be plotted .
thereby , the effects of these parameters can be visualized .
there are three critical values in the inter - species interaction @xmath0 and one in the ratio of particle numbers @xmath1 .
they govern the transitions between the phases .
two cases , ( i ) the repulsive @xmath2 matches the repulsive @xmath3 , and ( ii ) the attractive @xmath2 nearly cancels the effect of the repulsive @xmath4 have been particularly taken into account .
the former leads to a complete separation of the two kinds of atoms , while the latter lead to a collapse .
finally , based on an equation derived in the paper , a convenient experimental approach is proposed to determine the ratio of particle numbers . * correspondence to [email protected] .
And you have already written the first three sentences of the full article: there is increasing interest in two - species bose - einstein condensate ( tbec ) in last two decades since it was first studied theoretically by ho and shenoy@xcite , and was achieved experimentally by myatt , et al.@xcite .
the tbec provides an important tool to clarify the inter - species and intra - species interactions . besides
, molecules in well defined rovibrational levels with permanent electric - dipole moment can be thereby obtained , and they are valuable for studying the strongly interacting quantum gases.ospe06,webe08,ni08,bara08 . experimentally , the rb - cs mixture has been realized via a magnetic trap @xcite or an optical trap @xcite ..
Please generate the next two sentences of the article | the rb - yb mixture has been realized via a combined magneto - optical trap nemi09 .
the k - rb , na - rb , sr - rb and the isotopic mixtures @xmath5rb-@xmath6rb , @xmath7yb-@xmath8yb , @xmath9sr-@xmath10sr , and @xmath10sr-@xmath11sr have also been realized and studied recently ( refer to the references listed in @xcite ) . |
8,241 | Suppose that you have an abstract for a scientific paper: today s person detection methods work best when people are in common upright poses and appear reasonably well spaced out in the image . however , in many real images , that s not what people do .
people often appear quite close to each other , e.g. , with limbs linked or heads touching , and their poses are often not pedestrian - like . we propose an approach to detangle people in multi - person images .
we formulate the task as a region assembly problem . starting from a large set of overlapping regions from body part semantic segmentation and generic object proposals , our optimization approach reassembles those pieces together into multiple person instances .
it enforces that the composed body part regions of each person instance obey constraints on relative sizes , mutual spatial relationships , foreground coverage , and exclusive label assignments when overlapping . since optimal region assembly
is a challenging combinatorial problem , we present a lagrangian relaxation method to accelerate the lower bound estimation , thereby enabling a fast branch and bound solution for the global optimum . as output ,
our method produces a pixel - level map indicating both 1 ) the body part labels ( arm , leg , torso , and head ) , and 2 ) which parts belong to which individual person .
our results on three challenging datasets show our method is robust to clutter , occlusion , and complex poses .
it outperforms a variety of competing methods , including existing detector crf methods and region cnn approaches .
in addition , we demonstrate its impact on a proxemics recognition task , which demands a precise representation of whose body part is where " in crowded images .
= 1 .
And you have already written the first three sentences of the full article: person detection has made tremendous progress over the last decade @xcite .
standard methods work best on pedestrians : upright people in fairly simple , predictable poses , and with minimal interaction and occlusion between the person instances .
unfortunately , people in real images are not always so well - behaved.
Please generate the next two sentences of the article | ! plenty of in - the - wild images contain multiple people close together , perhaps with their limbs intertwined , faces close , bodies partially occluded , and in a variety of poses .
a number of computer vision applications demand the ability to parse such natural images into individual people and their respective body parts for example , fashion @xcite , consumer photo analysis , predicting inter - person interactions @xcite , or as a stepping stone towards activity recognition , gesture , and pose analysis . |
8,242 | Suppose that you have an abstract for a scientific paper: x - ray evidence for ultra - fast outflows ( ufos ) has been recently reported in a number of local agns through the detection of blue - shifted fe xxv / xxvi absorption lines .
we present the results of a comprehensive spectral analysis of a large sample of 42 local seyferts and 5 broad - line radio galaxies ( blrgs ) observed with _
xmm - newton _ and _ suzaku_. we detect ufos in @xmath040% of the sources .
their outflow velocities are in the range @xmath10.030.3c , with a mean value of @xmath10.14c .
the ionization is high , in the range log@xmath2@xmath136 erg s@xmath3 cm , and also the associated column densities are large , in the interval @xmath1@xmath4@xmath5 @xmath6 .
overall , these results point to the presence of highly ionized and massive outflowing material in the innermost regions of agns .
their variability and location on sub - pc scales favor a direct association with accretion disk winds / outflows .
this also suggests that ufos may potentially play a significant role in the agn cosmological feedback besides jets and their study can provide important clues on the connection between accretion disks , winds and jets . .
And you have already written the first three sentences of the full article: the recent detection of blue - shifted fe xxv / xxvi absorption lines in the x - ray spectra of several seyferts and quasars suggests the presence of highly ionized and mildly - relativistic outflows in the center of these agns ( e.g. , chartas et al .
2002 , 2003 ; pounds et al . 2003 ; dadina et al . 2005 ; markowitz et al .
2006 ; braito et al ..
Please generate the next two sentences of the article | 2007 ; cappi et al . 2009
; reeves et al . 2009 ; giustini et al . |
8,243 | Suppose that you have an abstract for a scientific paper: we show that a consistent fit to observed secondary eclipse data for several strongly irradiated transiting planets demands a temperature inversion ( stratosphere ) at altitude .
such a thermal inversion significantly influences the planet / star contrast ratios at the secondary eclipse , their wavelength dependences , and , importantly , the day - night flux contrast during a planetary orbit .
the presence of the thermal inversion / stratosphere seems to roughly correlate with the stellar flux at the planet .
such temperature inversions might caused by an upper - atmosphere absorber whose exact nature is still uncertain . .
And you have already written the first three sentences of the full article: theoretical modeling of atmospheres of extrasolar giant planets ( egp ) is a young field , about one decade old , and as youngsters usually are , it is very active , restless , and sometimes quite unpredictable .
it had recently undergone a transition from a purely care - free stage ( no observations were available ) to a more difficult stage where there already are some observations to be fit by the theory . in this paper
, we briefly describe our recent efforts in this area ..
Please generate the next two sentences of the article | we will try to convince the reader that despite its young age and many shortcomings , the theory is actually doing quite well .
the basic aim of a model atmosphere is to predict both the structure ( physical and chemical state ) of an atmosphere as a function of depth , as well as the theoretical emergent spectrum . |
8,244 | Suppose that you have an abstract for a scientific paper: we study the dynamics of spin flipping at first order transitions in zero temperature two - dimensional random - field ising model driven by an external field . we find a critical value of the disorder strength
at which a discontinuous sharp jump in magnetization first occurs .
we discuss growth morphology of the flipped - spin domains at and away from criticality . .
And you have already written the first three sentences of the full article: the _ random field ising model _ @xmath0 has been widely studied in recent years in the context of hysteresis [ 1 - 3 ] , return - point memory [ 4,5 ] and barkhausen noise [ 6 - 11 ] .
hysteresis is a common phenomenon , exhibited , for example , by most magnetic materials . in hysteresis
the magnetization lags behind the applied field and the phenomenon has received lots of attention in the past . moreover ,.
Please generate the next two sentences of the article | if one observes carefully , the change in magnetization in systems like that in ferromagnetic alloys and amorphous ferromagnets , takes place in a series of irregular pulses as the external field is slowly varied . in experiments these pulses manifest themselves as acoustic emissions and is known as barkhausen noise .
interestingly , barkhausen signals show scale - free behavior similar to that of systems at criticality . barkhausen noise has been studied much in recent years in the context of driven disordered systems far from equilibrium example |
8,245 | Suppose that you have an abstract for a scientific paper: the 21 cm signal from the epoch of reionization should be observed within the next decade .
while a simple statistical detection is expected with ska pathfinders , the ska will hopefully produce a full 3d mapping of the signal . to extract from the observed data constraints on the parameters describing the underlying astrophysical processes ,
inversion methods must be developed .
for example , the markov chain monte carlo method has been successfully applied . here
we test another possible inversion method : artificial neural networks ( ann ) .
we produce a training set which consists of 70 individual sample .
each sample is made of the 21 cm power spectrum at different redshifts produced with the 21cmfast code plus the value of three parameters used in the semi - numerical simulations that describe astrophysical processes . using this set we train the network to minimize the error between the parameter values it produces as an output and the true values .
we explore the impact of the architecture of the network on the quality of the training .
then we test the trained network on the new set of 54 test samples with different values of the parameters .
we find that the quality of the parameter reconstruction depends on the sensitivity of the power spectrum to the different parameters at a given redshift , that including thermal noise and sample variance decreases the quality of the reconstruction and that using the power spectrum at several redshifts as an input to the ann improves the quality of the reconstruction .
we conclude that anns are a viable inversion method whose main strength is that they require a sparse exploration of the parameter space and thus should be usable with full numerical simulations .
[ firstpage ] cosmology : theory intergalactic medium epoch of reionization 21 cm line .
And you have already written the first three sentences of the full article: according to the standard hierarchical structure formation theory based on the @xmath0cdm cosmology model , density perturbations grow into small haloes where the first stars and galaxies form ( e.g. * ? ? ?
* ; * ? ? ?
* ; * ? ? ?.
Please generate the next two sentences of the article | * ; * ? ? ?
these astrophysical sources produce ultraviolet ( uv ) ionizing photons that escape into the intergalactic medium ( igm ) which is eventually reionized . |
8,246 | Suppose that you have an abstract for a scientific paper: the mechanical properties of crystalline materials can be substantially modified under confinement .
such modified macroscopic properties are usually governed by the altered microstructures and internal stress fields . here
, we use a parallel plate geometry to apply a quasi - static squeeze flow crushing a colloidal polycrystal while simultaneously imaging it with confocal microscopy .
the confocal images are used to quantify the local structure order and , in conjunction with stress assessment from local structural anisotropy ( salsa ) , determine the stress at the single - particle scale .
we find that during compression , the crystalline regions break into small domains with different geometric packing .
these domains are characterized by a pressure and deviatoric stress that are highly localized with correlation lengths that are half those found in bulk .
furthermore , the mean deviatoric stress almost doubles , suggesting a higher brittleness in the highly - confined samples . .
And you have already written the first three sentences of the full article: understanding the effect of confinement on crystalline materials is crucial to many technological applications , such as lubrication , adhesion , and fabricating novel optical , catalytic materials @xcite .
for example , during film processes , which are important for optoelectronics , magnetic and electronic materials @xcite , internal stresses often arise affecting the mechanical stability and strength of the film @xcite . here
we study increasingly confined colloidal crystals to investigate how changes in their microstructure affect the microscopic stresses ultimately responsible for their bulk mechanical properties ..
Please generate the next two sentences of the article | such colloidal systems are comprised of particles small enough to undergo brownian motions that preserve a thermodynamic ensemble , while still large enough to be optically imaged with high temporal and spatial resolutions @xcite .
as such , colloidal crystals have been widely used as a model system to elucidate many phenomena associated with confinement including crystal growth @xcite , packing @xcite , and melting mechanisms@xcite . in principle , knowing all particle positions and their interactions is sufficient to determine the suspension s structural order and stress distribution . |
8,247 | Suppose that you have an abstract for a scientific paper: we performed 3-d simulations of proton - rich material entrainment into @xmath0-rich he - shell flash convection and the subsequent h - ingestion flash that took place in the post - agb star sakurai s object .
observations of the transient nature and anomalous abundance features are available to validate our method and assumptions , with the aim to apply them to very low metallicity stars in the future .
we include nuclear energy feedback from h burning and cover the full @xmath1 geometry of the shell .
runs on @xmath2 and @xmath3 grids agree well with each other and have been followed for @xmath4 and @xmath5 . after a @xmath6 long quiescent entrainment phase the simulations enter into a global non - spherical oscillation that is launched and sustained by individual ignition events of h - rich fluid pockets .
fast circumferential flows collide at the antipode and cause the formation and localized ignition of the next h - overabundant pocket .
the cycle repeats for more than a dozen times while its amplitude decreases . during the global oscillation
the entrainment rate increases temporarily by a factor @xmath7 .
entrained entropy quenches convective motions in the upper layer until the burning of entrained h establishes a separate convection zone .
the lower - resolution run hints at the possibility that another global oscillation , perhaps even more violent will follow .
the location of the h - burning convection zone agrees with a 1-d model in which the mixing efficiency is calibrated to reproduce the light curve .
the simulations have been performed at the nsf blue waters supercomputer at ncsa . .
And you have already written the first three sentences of the full article: convective - reactive h - combustion events are encountered when the damkhler number @xmath8 , where @xmath9 is the reaction time scale for the @xmath10 reaction and @xmath11 is the convective advection time scale @xcite . in such events
h is ingested into he - shell flash convection , and this is encountered in many instances of stellar evolution , especially at very low or zero metallicity .
examples have been found in 1-d stellar evolution simulations and include the he - core and he - shell flashes with h - ingestion events in low - mass stars with [ fe / h]@xmath12 ( e.g. * ? ? ?.
Please generate the next two sentences of the article | * ; * ? ? ?
* ; * ? ? ? |
8,248 | Suppose that you have an abstract for a scientific paper: we prove the equivalence between the smoothing effect for a schrdinger operator and the decay of the associate spectral projectors .
we give two applications to the schrdinger operator in dimension one .
on donne une caractrisation de leffet rgularisant pour un oprateur de schrdinger par la dcroissance de ses projecteurs spectraux . on
en dduit deux applications loprateur de schrdinger en dimension un . .
And you have already written the first three sentences of the full article: let @xmath0 , and consider the linear schrdinger equation @xmath1 where @xmath2 is a self - adjoint operator on @xmath3 .
+ by the hille - yoshida theorem , the equation admits a unique solution @xmath4 . under suitable conditions on @xmath2
, this solution enjoys a local gain of regularity ( in the space variable ) : for all @xmath5 there exists @xmath6 so that @xmath7 for some weight @xmath8 and exponent @xmath9 . +.
Please generate the next two sentences of the article | this phenomenon has been discovered by t. kato @xcite in the context of kdv equations .
for the schrdinger equation in the case @xmath10 , it has been proved by p. constantin- j .- c . |
8,249 | Suppose that you have an abstract for a scientific paper: the paper is devoted to penalty robin robin domain decomposition methods ( ddms ) , proposed by us for the solution of unilateral multibody contact problems of elasticity .
these ddms are based on the penalty method for variational inequalities and some stationary and nonstationary iterative methods for nonlinear variational equations .
the main result of the paper is that we give mathematical justification of proposed ddms and prove theorems about their convergence .
we also provide numerical investigations of the efficiency of these methods using finite element approximations .
* key words : * elasticity , multibody contact , variational inequalities , penalty method , iterative methods , domain decomposition * msc2010 : * 65n55 , 74s05 .
And you have already written the first three sentences of the full article: contact problems of elasticity are widely used in many fields of science and engineering , especially in machine science , structural mechanics , geology and biomechanics .
the brief overview of existing numerical and analytical methods for the solution of contact problems can be found in @xcite .
efficient approach to the solution of multibody contact problems is the use of domain decomposition methods ( ddms ) ..
Please generate the next two sentences of the article | ddms are well developed for the solution of linear boundary value problems , particularly for linear poisson and linear elasticity problems @xcite . the construction of ddms for unilateral contact problems , which are nonlinear , are much more complicated .
among domain decomposition methods for unilateral two - body contact problems obtained on continuous level , one should mention signorini |
8,250 | Suppose that you have an abstract for a scientific paper: the growing availability of network data and of scientific interest in distributed systems has led to the rapid development of statistical models of network structure . typically , however , these are models for the entire network , while the data consists only of a sampled sub - network .
parameters for the whole network , which is what is of interest , are estimated by applying the model to the sub - network .
this assumes that the model is _ consistent under sampling _ , or , in terms of the theory of stochastic processes , that it defines a projective family .
focusing on the popular class of exponential random graph models ( ergms ) , we show that this apparently trivial condition is in fact violated by many popular and scientifically appealing models , and that satisfying it drastically limits ergm s expressive power .
these results are actually special cases of more general results about exponential families of dependent random variables , which we also prove . using such results ,
we offer easily checked conditions for the consistency of maximum likelihood estimation in ergms , and discuss some possible constructive responses . .
And you have already written the first three sentences of the full article: in recent years , the rapid increase in both the availability of data on networks ( of all kinds , but especially social ones ) and the demand , from many scientific areas , for analyzing such data has resulted in a surge of generative and descriptive models for network data @xcite . within statistics ,
this trend has led to a renewed interest in developing , analyzing and validating statistical models for networks @xcite . yet as networks are a nonstandard type of data , many basic properties of statistical models for networks are still unknown or have not been properly explored . in this article
we investigate the conditions under which statistical inferences drawn over a sub - network will generalize to the entire network ..
Please generate the next two sentences of the article | it is quite rare for the data to ever actually be the _ whole _ network of relations among a given set of nodes or units ; typically , only a sub - network is available .
guided by experience of more conventional problems like regression , analysts have generally fit models to the available sub - network , and then extrapolated them to the larger true network which is of actual scientific interest , presuming that the models are , as it were , consistent under sampling . |
8,251 | Suppose that you have an abstract for a scientific paper: we discuss in detail the semiclassical approximation for the cghs model of two - dimensional dilatonic black holes .
this is achieved by a formal expansion of the full wheeler - dewitt equation and the momentum constraint in powers of the gravitational constant . in highest order
, the classical cghs solution is recovered .
the next order yields a functional schrdinger equation for quantum fields propagating on this background .
we show explicitly how the hawking radiation is recovered from this equation .
although described by a pure quantum state , the expectation value of the number operator exhibits a planckian distribution with respect to the hawking temperature .
we then show how this hawking radiation can lead to the decoherence of black hole superpositions .
the cases of a superposition of a black hole with a white hole , as well as of a black hole with no hole , are treated explicitly .
decoherence of black holes by hawking radiation 0.3truein jean - guy demers + + + claus kiefer + + + 0.5truein .4truein .5 in .
And you have already written the first three sentences of the full article: one of the main applications of any quantum theory of gravity should be the complete understanding of black hole evaporation .
since such a theory is not yet available , attention has been focused on simpler models whose quantization is expected to be tractable .
most notably among these are the models of two - dimensional dilaton gravity ( see , for example , @xcite for a detailed review ) ..
Please generate the next two sentences of the article | although much insight has been gained into the evaporation process and , in particular , the back reaction of the hawking radiation onto the black hole and the problem of information loss " , a full understanding of the complete , non - perturbative , evolution remains elusive .
the reason for this is that even for such models the full quantum theory is not known . at present , |
8,252 | Suppose that you have an abstract for a scientific paper: we show that an expected number ratio of radial arcs ( gravitationally lensed images whose major axes lie in the radial direction of a cluster - lens potential ) to tangential arcs ( gravitationally lensed images whose major axes lie in the tangential direction ) has strong dependence on the central density profile of galaxy clusters and has little dependence on other parameters , e.g. cluster temperature , background source galaxy redshift etc .. a comparison of the expected number ratios with observed ratios provides a robust test to constrain the central density profile of galaxy clusters .
a tentative comparison with the observational data shows that the central density profile of galaxy clusters is @xmath0 .
this result indicates that the dark matter is collisionless at least on cluster scale .
our result gives an upper limit on a collision cross - section of self - interaction of dark matter ( @xmath1 ) as @xmath2 where @xmath3 is a dark matter particle mass . .
And you have already written the first three sentences of the full article: the central density profile of dark matter halos around galaxies and galaxy clusters is now highlighted in the dark matter cosmology .
@xcite have performed cosmological n - body simulations based on cold dark matter models and show that the equilibrium density profiles of dark matter halos have self - similar profiles . the profile ( hereafter , nfw profile )
is thought to be the final relaxed state of self - gravitating collisionless particles and thereby called a universal profile ..
Please generate the next two sentences of the article | the nfw profile has a central cusp diverging as @xmath4 .
recent simulations with higher resolution have confirmed existence of a universal profile but show that the central density profile gets steeper and is better represented by @xmath5 @xcite although slight variation of the central density profiles from halo to halo is reported @xcite . |
8,253 | Suppose that you have an abstract for a scientific paper: foundations of _ algebrodynamics _ based on earlier proposed equations of _ biquaternionic holomorphy _ are briefly expounded .
free maxwell and yang - mills eqs .
are satisfied identically on the solutions of primary system which is also related to the eqs . of _
shear - free null congruences _ ( sfc ) , and through them - to the einstein - maxwell electrovacuum system . _
kerr theorem _ for sfc reduces the basic system to one algebraic equation , so that with each solution of the latter some ( singular ) solution of vacuum eqs . may be associated .
we present some exact solutions of basic algebraic and of related field eqs . with _
compact _ structure of singularities of electromagnetic field , in particular having the form of _ figure `` 8 '' curve_. fundamental solution to primary system is analogous to the metric and fields of the _ kerr - newman _ solution .
in addition , in the framework of algebraic dynamics the value of _ electric charge _ for this solution is strictly fixed in magnitude and may be set equal to the _ elementary charge_. .
And you have already written the first three sentences of the full article: as the main goal of the _ algebrodynamical _ approach @xcite , we regard the derivation of equations of physical fields ( or of fundamental physical laws , in a broader sense ) from a unique primary _ principle of purely abstract nature _ , based only on the intrinsic properties of exclusive mathematical structures ( groups , algebras , mappings etc . ) .
basic realization of this concept developed in @xcite makes use of only the _ differentiability conditions _ of functions of _ biquaternionic variable _ ,
i.e. of the cauchy - riemann ( cr ) equations generalized to the case of noncommutative ( associative ) algebras . in the framework of the version of analysis proposed in @xcite.
Please generate the next two sentences of the article | the noncommutativity of starting algebra naturally results in the nonlinearity of generalized cr equations ( gcre ) , justifying the use of the latters as the dynamical equations of _ interacting _ fields .
infact , for the algebra of biquaternions @xmath0 ( isomorphic to the full @xmath1 complex matrix algebra ) the gcre appear to be lorentz invariant and carry natural 2-spinor and gauge structures . in the most examined case |
8,254 | Suppose that you have an abstract for a scientific paper: we study pattern formation associated with the polarization degree of freedom of the electric field amplitude in a mean field model describing a nonlinear kerr medium close to a two - photon resonance , placed inside a ring cavity with flat mirrors and driven by a coherent @xmath0-polarized plane - wave field . in the self - focusing case , for negative detunings
the pattern arises naturally from a codimension two bifurcation . for a critical value of the field intensity
there are two wave numbers that become unstable simultaneously , corresponding to two turing - like instabilities .
considered alone , one of the instabilities would originate a linearly polarized hexagonal pattern whereas the other instability is of pure vectorial origin and would give rise to an elliptically polarized stripe pattern .
we show that the competition between the two wavenumbers can originate different structures , being the detuning a natural selection parameter . .
And you have already written the first three sentences of the full article: spatiotemporal patterns in the transverse direction of an optical field have now been widely studied theoretically and experimentally @xcite .
studies of optical pattern formation share a number of aspects and techniques with general investigations of pattern formation in other physical systems @xcite , but they also have specific features such as the role of light diffraction and the vectorial degree of freedom associated with the polarization of the light electric field amplitude . a prototype simple model which has been very useful for the understanding of pattern formation in nonlinear optical cavities is a mean field model describing a kerr medium in a cavity with flat mirrors and driven by a coherent plane - wave field@xcite .
this model was extended to take into account the polarization degrees of freedom in @xcite ..
Please generate the next two sentences of the article | some of the basic polarization mechanisms of pattern formation in alkali vapors or other non - linear materials can be understood in terms of this simple model despite the fact that the model is too simple to give a complete description of alkali vapors .
furthermore , the relative simplicity of the model in @xcite makes it worthwhile to study it in depth as a general prototype model for the basic understanding of vectorial patterns . |
8,255 | Suppose that you have an abstract for a scientific paper: if bilayer graphene is placed in a strong perpendicular magnetic field , several quantum hall plateaus are observed at low enough temperatures . of these ,
the @xmath0 sequence ( @xmath1 ) is explained by standard landau quantization , while the other integer plateaus arise due to interactions .
the low - energy excitations in both cases are magnetoexcitons , whose dispersion relation depends on single- and many - body effects in a complicated manner . analyzing the magnetoexciton modes in bilayer graphene , we find that the mixing of different landau level transitions not only renormalizes them , but essentially changes their spectra and orbital character at finite wave length .
these predictions can be probed in inelastic light scattering experiments . .
And you have already written the first three sentences of the full article: bilayer graphene,@xcite two coupled hexagonal lattices of carbon atoms in the bernal stacking@xcite of graphite , is a two - dimensional zero - gap semiconductor with chiral charge carriers with berry s phase @xmath2 , having a roughly parabolic dispersion at low energies about the corners of the hexagonal first brillouin zone.@xcite these facts are testified by its unusual integer quantum hall effect@xcite ( iqhe ) , featuring a double step in the ladder of the hall conductance in a strong perpendicular magnetic field @xmath3 , observed by novoselov _
_ et al.__@xcite this double step , @xmath4 instead of the common @xmath5 for spin and valley degenerate landau levels , is due to the degeneracy of the @xmath6 landau orbitals.@xcite the gap at the integer quantum hall effect at filling factor @xmath7 has been recently measured with great accuracy,@xcite and the excitations of the iqhe states in the long wavelength limit have also been observed by infrared absorption@xcite and raman spectrocopy.@xcite further broken symmetry states have been observed@xcite in the central landau band at @xmath8 and @xmath9 , and by careful tilted - field measurements it has been shown that they arise predominantly from many - body effects , i.e. , from quantum hall ferromagnetism ( qhf).@xcite quantum hall states with broken symmetry have also been found in the @xmath10 landau level@xcite , and there is also some evidence for a fractional quantum hall plateau .
the eightfold degeneracy of the central group of landau levels is at best approximate , because the zeeman energy is unavoidably present ..
Please generate the next two sentences of the article | while the latter is rather small on the characteristic scale of the interaction energy , a perpendicular electric field can be applied to bias the two layers,@xcite which causes an energy difference between the two valleys .
the competition of the on - site energy difference between the layers and interactions may result in interesting physics , especially at @xmath11.@xcite if the chemical potential is in the gap between landau bands , the low - energy excitations are bound particle - hole pairs,@xcite called magnetoexcitons . as the net charge of such an excitation is zero , taking appropriate linear combinations one obtains eigenstates of the total momentum . in such states |
8,256 | Suppose that you have an abstract for a scientific paper: we compare data of antineutron and antiproton annihilation cross sections on different targets at very low energies . after subtracting coulomb effects , we observe that the ratio between the @xmath0 and @xmath1 annihilation cross sections is an oscillating function of the energy at momenta smaller 300 mev / c .
this nontrivial behavior is confirmed by the analysis of the relative number of @xmath2 and @xmath1 annihilations in nuclei .
we show that a part of the strong shadowing phenomena in @xmath3-nucleus annihilations can be explained in terms of this oscillation , while a part requires different explainations . , , , , , , , .
And you have already written the first three sentences of the full article: recently data on @xmath0 annihilation in the range 40 - 400 mev / c ( for the laboratory @xmath4 momentum @xmath5 ) have been produced by the obelix collaboration@xcite .
we would like to compare these with other data on @xmath1 and @xmath6-nucleus annihilation .
in particular , we are interested in : @xmath4 annihilation on nuclei from @xmath7c to @xmath8pb in the range 180 - 280 mev / c@xcite ; @xmath1 annihilation from 30 to 180 mev / c@xcite ; @xmath3d , @xmath9he and @xmath10ne at small momenta , down to 45 mev / c@xcite ; @xmath3-nucleus annihilation on intermediate nuclei at larger momenta ( over 200 mev / c , see@xcite for a recollection of these data ) ; and on the ratio between @xmath1 and @xmath2 annihilations inside nuclear targets@xcite.
Please generate the next two sentences of the article | . we will start by comparing @xmath1 and @xmath0 data , and then we will try to correlate these with the low energy nuclear data .
one of our aims is simply to compare @xmath0 and @xmath1 annihilation cross sections . |
8,257 | Suppose that you have an abstract for a scientific paper: physical properties of polycrystalline cecrge@xmath0 and lacrge@xmath0 have been investigated by x - ray absorption spectroscopy , magnetic susceptibility @xmath1 , isothermal magnetization m(h ) , electrical resistivity @xmath2 , specific heat c(@xmath3 ) and thermoelectric power s(@xmath3 ) measurements .
these compounds are found to crystallize in the hexagonal perovskite structure ( space group _ p6@xmath0/mmc _ ) , as previously reported .
the @xmath2 , @xmath1 and c(@xmath3 ) data confirm the bulk ferromagnetic ordering of itinerant cr moments in lacrge@xmath0 and cecrge@xmath0 with @xmath4 = 90 k and 70 k respectively .
in addition a weak anomaly is also observed near 3 k in the c(@xmath3 ) data of cecrge@xmath0 .
the t dependences of @xmath5 and finite values of sommerfeld coefficient @xmath6 obtained from the specific heat measurements confirm that both the compounds are of metallic character .
further , the @xmath3 dependence of @xmath5 of cecrge@xmath0 reflects a kondo lattice behavior .
an enhanced @xmath6 of 130 mj / molk@xmath7 together with the kondo lattice behavior inferred from the @xmath2 establish cecrge@xmath0 as a moderate heavy fermion compound with a quasi - particle mass renormalization factor of @xmath8 45 . .
And you have already written the first three sentences of the full article: superconductivity in iron pnictide was discovered at the boundary of magnetically ordered and non - ordered state of fe - magnetism .
the spin - density - wave type antiferromagnetic order in rfeaso ( r = la , ce , pr , nd , sm ) and afe@xmath9as@xmath9 ( a = ca , ba , sr , eu ) could be suppressed by carrier doping@xcite or by application of chemical / externally applied pressure@xcite .
one may expect to find similar interesting results by tuning the magnetic state of cr - moments as well ..
Please generate the next two sentences of the article | recently cr - magnetic ordering at relatively low temperature has been reported in rcrge@xmath0 system where r stands for rare - earth elements @xcite . on the other hand , ce - based ternary germanide , rtge@xmath0 ( r = rare - earth elements and t = @xmath10 elements ) system exhibits some interesting magnetic properties .
for instance , cerhge@xmath0 shows a weak kondo effect along with three magnetic phase transitions @xcite . |
8,258 | Suppose that you have an abstract for a scientific paper: reverberation mapping ( rm ) is an important technique in studies of active galactic nuclei ( agn ) .
the key idea of rm is to measure the time lag @xmath0 between variations in the continuum emission from the accretion disc and subsequent response of the broad line region ( blr ) .
the measurement of @xmath0 is typically used to estimate the physical size of the blr and is combined with other measurements to estimate the black hole mass @xmath1 .
a major difficulty with rm campaigns is the large amount of data needed to measure @xmath0 .
recently , @xcite introduced a new approach to rm where the blr light curve is sparsely sampled , but this is counteracted by observing a large sample of agn , rather than a single system .
the results are combined to infer properties of the sample of agn . in this letter
we implement this method using a hierarchical bayesian model and contrast this with the results from the previous stacked cross - correlation technique .
we find that our inferences are more precise and allow for more straightforward interpretation than the stacked cross - correlation results .
[ firstpage ] galaxies : active methods : data analysis .
And you have already written the first three sentences of the full article: reverberation mapping ( rm ) is a key technique for the study of active galactic nuclei ( agn ) .
the technique is based on the temporal fluctuations of the central continuum source , and the subsequent response of the broad line region ( blr ) emission .
the time delay between the continuum and the broad line fluctuations provides an estimate of the size of the blr , and can also be used to estimate the black hole mass @xcite ..
Please generate the next two sentences of the article | rm is a observationally intensive , requiring observations of an agn over a period of a few tens of days @xcite . as a result , many authors have studied the data analysis techniques involved in rm , and substantial advances have been made in recent years .
the data analysis methods introduced range from those that attempt to infer the transfer function ( the distribution of lags in a single object , e.g. * ? ? ? |
8,259 | Suppose that you have an abstract for a scientific paper: programable spatial light modulators ( slms ) have significantly advanced the configurable optical trapping of particles .
typically , these devices are utilized in the fourier plane of an optical system , but direct imaging of an amplitude pattern can potentially result in increased simplicity and computational speed . here
we demonstrate high - resolution direct imaging of a digital micromirror device ( dmd ) at high numerical apertures ( na ) , which we apply to the optical trapping of a bose - einstein condensate ( bec ) .
we utilise a ( @xmath0 ) pixel dmd and commercially available 0.45 na microscope objectives , finding that atoms confined in a hybrid optical / magnetic or all - optical potential can be patterned using repulsive blue - detuned ( 532 nm ) light with 630(10 ) nm full - width at half - maximum ( fwhm ) resolution , within 5% of the diffraction limit .
the result is near arbitrary control of the density the bec without the need for expensive custom optics .
we also introduce the technique of time - averaged dmd potentials , demonstrating the ability to produce multiple grayscale levels with minimal heating of the atomic cloud , by utilising the high switching speed ( 20 khz maximum ) of the dmd .
these techniques will enable the realization and control of diverse optical potentials for superfluid dynamics and atomtronics applications with quantum gases .
the performance of this system in a direct imaging configuration has wider application for optical trapping at non - trivial nas . .
And you have already written the first three sentences of the full article: the manipulation of microscopic particles has benefited from the high level of control and measurement provided by optical tweezers . with the technological development of fast configurable spatial light modulators ( slms ) allowing for ever more complex trapping geometries @xcite , new applications have emerged .
for example , sculpted light may have an important role in overcoming multiple light scattering issues in complex biological tissues , and such biomedical applications have only begun to be explored .
in particular the development of sculpted light patterns across the image plane , such as the generation of large trapping arrays , could have application to the in vivo trapping of larger objects , such as living cells @xcite . in degenerate quantum gases ,.
Please generate the next two sentences of the article | the push for increasing diversification of optical trapping potentials has led to the adoption of many of the techniques from holographic optical tweezers .
slms are most often used in the fourier plane of an optical system , manipulating the phase of an input optical field to produce a configurable pattern in the conjugate trapping plane of the system @xcite . |
8,260 | Suppose that you have an abstract for a scientific paper: we discuss the first results from ongoing studies of the resolved stellar populations in the outskirts of our nearest large neighbour , m31 .
deep hst / wfpc2 archival observations are used to construct colour - magnitude - diagrams which reach well below the horizontal branch at selected locations in the outer disk and halo , while a panoramic ground - based imaging survey maps spatial density variations through resolved star counts to a projected radius of @xmath0kpc . .
And you have already written the first three sentences of the full article: the fossil record of star formation and galaxy evolution is imprinted on the spatial distribution , ages and metallicities of galactic stellar populations .
surprisingly little is known about the old and intermediate - age stellar populations in massive galaxies outside our own milky way .
located at @xmath1780 kpc , m31 provides our best opportunity to explore the stellar populations across the face of a large disk galaxy ..
Please generate the next two sentences of the article | furthermore , its favourable inclination means that the disk and halo components at large radii can be easily distinguished and independently studied .
most previous studies of m31 have either been based on observations of single fields ( eg . |
8,261 | Suppose that you have an abstract for a scientific paper: study of parton distribution function ( pdf ) is a topic of significant interest in qcd . to overcome the shortcomings of conventional pdfs
, several alternative methods have been suggested in recent years .
the present work reports the @xmath0-distribution of the non - singlet structure function using the complete solution of taylor - approximated dglap equation .
the formalism is more general than the similar ones reported in recent literature .
our predictions are compared with the ccfr neutrino data as well as exact results . * keywords * : non - singlet structure function , @xmath0-evolution , leading order , low and high @xmath0 * pacs nos . * : 12.38.-t,12.38.bx,13.60-hb . .
And you have already written the first three sentences of the full article: recently @xcite we have reported the @xmath1-evolution of the non - singlet structure functions at low and high @xmath0 as the complete solution of taylor - approximated dglap equation @xcite .
the present paper reports the prediction of corresponding @xmath0-evolution .
although the conventional wisdom on dglap evolution does not favour such a feature , such a possibility was reported @xcite sometime back ..
Please generate the next two sentences of the article | the main reason is that in this approach , the dglap equation is converted into a first order differential equation in two variables @xmath0 and @xmath1 ( @xmath2 ) instead of only @xmath1 and has @xmath0 evolution as its natural outcome .
there are , of course , various methods that have been developed recently like the brute - force @xcite , laguerre - polynomial @xcite and mellin - transformation @xcite etc . for numerical solution of dglap equation . |
8,262 | Suppose that you have an abstract for a scientific paper: in this paper we study dynamical chiral symmetry breaking in dimensionally regularized quenched qed within the context of dyson - schwinger equations . in @xmath0 dimensions
the theory has solutions which exhibit chiral symmetry breaking for all values of the coupling .
to begin with , we study this phenomenon both numerically and , with some approximations , analytically within the rainbow approximation in the landau gauge .
in particular , we discuss how to extract the critical coupling @xmath1 relevant in @xmath2 dimensions from the @xmath3 dimensional theory . we further present analytic results for the chirally symmetric solution obtained with the curtis - pennington vertex as well as numerical results for solutions exhibiting chiral symmetry breaking .
for these we demonstrate that , using dimensional regularization , the extraction of the critical coupling relevant for this vertex is feasible .
initial results for this critical coupling are in agreement with cut - off based work within the currently achievable numerical precision . .
And you have already written the first three sentences of the full article: it is fairly well established that quantum electrodynamics ( qed ) , and in particular quenched qed , breaks chiral symmetry for sufficiently large couplings . this phenomenon has been observed both in lattice simulations @xcite as well as various studies based on the use of dyson - schwinger equations @xcite .
these latter calculations have generally relied on the use of a cut - off in euclidean momentum in order to regulate divergent integrals , a procedure which breaks the gauge invariance of the theory . on the other hand , continuation of gauge theories to @xmath0 dimensions
has long been used as an efficient way to regularize perturbation theory without violating gauge invariance . in nonperturbative calculations , however , the use of this method of regularization is rarely used @xcite . within the context of the dyson - schwinger equations ( dses ) only a few publications @xcite.
Please generate the next two sentences of the article | have employed dimensional regularization instead of the usual momentum cut - off .
it is the purpose of the present paper to study dynamical chiral symmetry breaking and the chiral limit within dimensionally regularized quenched qed . we are motivated to do this by the wish to avoid some gauge ambiguities occurring in cut - off based work , which we discuss in sec . |
8,263 | Suppose that you have an abstract for a scientific paper: we present optical echelle spectra of four gamma - ray burst ( grb ) afterglows ( grb 050730 , grb 050820 , grb 051111 , and grb 060418 ) discovered during the first 1.5 years of operation of the _ swift _ satellite and localized by either the _ swift _ telescope or follow - up ground - based imaging .
we analyze the spectra to derive accurate column density measurements for the transitions arising in the interstellar medium ( ism ) of the grb host galaxies .
these measurements can be used to constrain the physical properties of the ism including the metallicity , dust - to - gas ratio , ionization state , and chemical abundances of the gas .
we also present measurements of the strong systems in the grb afterglow spectra . with the publication of this paper ,
we provide the first data release of echelle afterglow spectra by the graasp collaboration to the general community . .
And you have already written the first three sentences of the full article: the launch of the _ swift _ satellite @xcite has revolutionized the study of the interstellar medium of gamma - ray burst ( grb ) host galaxies and fostered new studies on the intervening intergalactic medium @xcite . while previous missions alerted the community to the existence of very bright grb afterglows ( e.g. * ? ? ?
* ) , only a few events were identified in time to allow echelle observations @xcite .
the rapid localization by _ swift _ of the hard x - ray emission to several arcminutes @xcite and the soft x - ray component to a few arcseconds @xcite has enabled observers to obtain high signal - to - noise , high - resolution spectroscopy of grbs with 10m - class telescopes . in this paper , we present a uniform dataset of echelle spectra of four grb afterglows by our grb afterglows as probes ( graasp ) collaboration . among other applications , the data presented here can be used to derive constraints on the physical conditions of the ism of grb host galaxies : the metallicity , dust - to - gas ratio , chemical abundance patterns , ionization state , the distance of the grb to the absorbing gas , etc ..
Please generate the next two sentences of the article | future papers in this series will examine these properties in greater detail and provide comparison with analogous observations along quasar sightlines .
in addition to the data presented here , we have collected several low - resolution spectra of these and other grbs and will present that data in a companion paper @xcite along with ism abundance measurements obtained by different analysis techniques more suitable to lower resolution data @xcite . |
8,264 | Suppose that you have an abstract for a scientific paper: the aim of these lectures is to provide students with an introduction to some of the core concepts and methods of qcd that are relevant in an lhc context . .
And you have already written the first three sentences of the full article: quantum chromodynamics , qcd , is the theory of quarks , gluons and their interactions .
it is central to all modern colliders .
and , for the most part , it is what we are made of ..
Please generate the next two sentences of the article | qcd bears a number of similarities to quantum electrodynamics ( qed ) .
just as electrons carry the qed charge , i.e. , electric charge , quarks carry the qcd charge , known as colour charge . |
8,265 | Suppose that you have an abstract for a scientific paper: we present a systematic investigation of attractive binary mixtures in presence of both spin- and mass - imbalance in one dimensional setups described by the hubbard model . after discussing typical cold atomic experimental realizations and the relation between microscopic and effective parameters , we study several many - body features of trapped fermi - fermi and bose - bose mixtures such as density profiles , momentum distributions and correlation functions by means of numerical density - matrix - renormalization - group and quantum monte carlo simulations .
in particular , we focus on the stability of fulde - ferrell - larkin - ovchinnikov , dimer and trimer fluids in inhomogeneous situations , as typically realized in cold gas experiments due to the harmonic confinement .
we finally consider possible experimental signatures of these phases both in the presence of a finite polarization and of a finite temperature . .
And you have already written the first three sentences of the full article: the study of superfluidity of either bosons or fermions has been a central topic in the field of ultracold atomic gases , starting from seminal experimental studies on the bose - einstein condensation of bosons @xcite and continuing with investigations of the bcs - bec crossover @xcite .
more recent experiments with two - component fermi gases have addressed the case of a finite population imbalanced , both in three spatial dimensions @xcite and in one dimension @xcite . among the goals of these experiments
is the search for the transition from a fully paired superfluid phase to the normal state and , in particular , for competing pairing states that survive a finite polarization ..
Please generate the next two sentences of the article | these include the sarma state @xcite or the fulde - ferrell - larkin - ovchinnikov ( fflo ) state @xcite . with the advances optical lattice engineering @xcite , it has also become possible to investigate fermionic pairing states within the framework of the so - called hubbard model . for repulsive onsite interactions
the hope is to reach sufficiently low temperatures to search for pairing states away from half filling @xcite , whereas in the case of attractive interactions , there is a natural tendency to pair formation . besides experiments with homonuclear mixtures , where the pseudo - spin degree of freedom arises from preparing atoms in different hyper - fine states , there is also the possibility of working with heteronuclear mixtures such as , for instance , the @xmath0k-@xmath1li system @xcite . in that case , one deals both finite mass imbalance and population imbalance . on the other hand , bosonic gases in optical lattices |
8,266 | Suppose that you have an abstract for a scientific paper: the weber problem consists of finding a point in @xmath0 that minimizes the weighted sum of distances from @xmath1 points in @xmath0 that are not collinear .
an application that motivated this problem is the optimal location of facilities in the 2-dimensional case .
a classical method to solve the weber problem , proposed by weiszfeld in 1937 , is based on a fixed point iteration . in this work
a weber problem constrained to a closed and convex set is considered .
a weiszfeld - like algorithm , well defined even when an iterate is a vertex , is presented .
the iteration function @xmath2 that defines the proposed algorithm , is based mainly on an orthogonal projection over the feasible set , combined with the iteration function of a modified weiszfeld algorithm presented by vardi and zhang in 2001 .
it can be seen that the proposed algorithm generates a sequence of feasible iterates that have descent properties . under certain hypotheses ,
the limit of this sequence satisfies the kkt optimality conditions , is a fixed point of the iteration function that defines the algorithm , and is the solution of the constrained minimization problem .
numerical experiments confirmed the theoretical results .
location , weber problem , weiszfeld algorithm , fixed point iteration 90b85 , 90c25 , 90c30 .
And you have already written the first three sentences of the full article: let @xmath3 be @xmath1 distinct points in the space @xmath0 , called vertices , and positive numbers @xmath4 , called weights .
the function @xmath5 defined by @xmath6 is called the weber function , where @xmath7 denotes the euclidean norm .
it is well - known that this function is not differentiable at the vertices , and strictly convex if the vertices are not collinear ( we will assume this hypothesis from now on ) ..
Please generate the next two sentences of the article | the weber problem ( also known as the fermat - weber problem ) is to find a point in @xmath0 that minimizes the weighted sum of euclidean distances from the @xmath1 given points , that is , we have to find the solution of the following unconstrained optimization problem : @xmath8 this problem has a unique solution @xmath9 in @xmath0 .
the problem was also stated as a pure mathematical problem by fermat @xcite , cavalieri @xcite , steiner @xcite , fasbender @xcite and many others . |
8,267 | Suppose that you have an abstract for a scientific paper: we show that a ferroelectric phase transition takes place in the incommensurate phase of the @xmath0 crystal .
the ferroelectric character of the ic phase explains the second - harmonic generation observed in the corresponding temperature range .
the crystals of the @xmath1 family ( about 20 crystals ) @xcite undergo two successive phase transitions on cooling : an incommensurate ( ic ) transition at temperature @xmath2 with a modulation vector near the @xmath3 point in the brillouin zone , and upon further cooling at temperature @xmath4 a commensurate lock - in transition to the triple - period ferroelectric phase with the modulation vector @xmath3 .
the most striking peculiarity of the @xmath0 crystal , which belongs to the @xmath1 family , is the second - harmonic generation ( shg ) in the ic phase,@xcite of the same intensity magnitude as that in the @xmath3- phase .
low temperature @xmath3- phases of the @xmath1 type crystals are improper ferroelectrics , and therefore the shg is a normal manifestation of this feature .
however , so far there was neither pointed out a plausible reason for the shg in the ic phase of @xmath0 , nor explained why it takes place not in all the crystals of the @xmath1 family .
it is worth noting that the shg was observed also in the ic phase of quartz by dolino and bachheimer ( 1977)@xcite and in the ic phase of the ammonium fluoroberyllate @xmath5 by alexandrov et al .
( 1978)@xcite , and both observations also can be explained using the theory developed below .
the attempt to explain the shg in the ic phase of @xmath5 was carried out by golovko and levanyuk@xcite based on the spatial dispersion of the dielectric constant .
however , the expected effect appeared to be small , and besides , it is not explained why in such a case the shg is not observed in all the crystals with the ic phases . in the present paper
we show that within the ic phase of the @xmath0 crystal , necessarily a transition to the ferroelectric ic phase takes place .
we analyze....
And you have already written the first three sentences of the full article: in order to calculate the derivative @xmath135 one should calculate the corresponding derivatives of the function @xmath136 .
so one obtains @xmath137 and @xmath138 @xmath139 we took into account that for the equilibrium value of @xmath32 , the condition @xmath140 holds , from which follows that @xmath141 .
similarly @xmath142 is also equal to zero ..
Please generate the next two sentences of the article | so , one obtains : @xmath143 for integration over @xmath28 in eq .
( 6 ) , the following relations are also used : @xmath144 where we used the right hand side of eq . |
8,268 | Suppose that you have an abstract for a scientific paper: some recent @xmath0-physics results are presented from the babar and belle experiments at the slac and kek b factories , which produce copious numbers of @xmath0-lepton pairs .
measurements of the tau mass and lifetime allow to test lepton universality and cpt invariance , while searches for lepton - flavour violation in tau decays are powerful ways to look for physics beyond the standard model .
in semihadronic , non - strange tau decays , the vector hadronic final state is particularly important in helping determine the hadronic corrections to the anomalous magnetic moment of the muon , while studies of strange final states are the best available ways to measure the ckm matrix element @xmath1 and the mass of the strange quark .
presented at charm 2006 , international workshop on tau - charm physics , june 05 - 07 2006 , beijing , china .
And you have already written the first three sentences of the full article: the slac and kek b factories are asymmetric e@xmath2e@xmath3 colliders which run at centre - of - mass energies at , and close to , the @xmath4 resonance . at these energies , around 10.58 gev
, the cross section for tau - pair production , at 0.89 nb , is close to the 1.05 nb cross section for b@xmath5 production .
these machines are therefore also tau factories , and the experiments babar and belle have between them so far recorded over @xmath6 tau - pair events . in comparison , the four lep experiments each recorded only about @xmath7 tau - pair events , mainly running on the z resonance , while cleo - iii at cesr took about @xmath8 tau - pair events ..
Please generate the next two sentences of the article | however , it should be noted that experimental conditions for tau physics at lep were particularly clean , resulting in relatively small systematic errors . for channels with large branching fractions , where systematic errors dominate
, the lep results will remain competitive for some time . |
8,269 | Suppose that you have an abstract for a scientific paper: bose - einstein correlations of pairs of identical charged pions produced in hadronic z decays are analyzed in terms of various parametrizations .
a good description is achieved using a lvy stable distribution in conjunction with a model where a particle s momentum is highly correlated with its space - time point of production , the @xmath0-model . however
, a small but significant elongation of the particle emission region is observed in the longitudinal center of mass frame , which is not accommodated in the @xmath0-model .
this is investigated using an _ ad hoc _ modification of the @xmath0-model .
bose - einstein correlations and the tau model + w.j .
metzger@xmath1 , t. novk@xmath2 , t. csrg@xmath3 , w. kittel@xmath1 + for the l3 collaboration + @xmath1radboud university , p.o .
box 9044 , 6500 kd nijmegen , netherlands + @xmath2kroly rbert college , 3200 gyngys , hungary + @xmath3mta kfki rmki , 1525 budapest 114 , hungary , and harvard university , + 17 oxford st . , cambridge , ma 02138 , u.s.a . .
And you have already written the first three sentences of the full article: we study bose - einstein correlations ( bec ) in hadronic @xmath4 decay using data collected by the l3 detector at an e@xmath5e@xmath6 center - of - mass energy of @xmath7 .
approximately 36 million like - sign pairs of well - measured charged tracks from about 0.8 million hadronic z decays are used @xcite .
events are classified as two- or three - jet events using calorimeter clusters with the durham jet algorithm with a jet resolution parameter @xmath8 , yielding about 0.5 million two - jet events ..
Please generate the next two sentences of the article | there are few events with more than three jets , and they are included in the three - jet sample . to determine the thrust axis of the event we also use calorimeter clusters .
the two - particle correlation function of two particles with four - momenta @xmath9 and @xmath10 is given by the ratio of the two - particle number density , @xmath11 , to the product of the two single - particle densities , @xmath12 . |
8,270 | Suppose that you have an abstract for a scientific paper: in the earlier work on the development of a model independent data analysis method for determining the mass of weakly interacting massive particles ( wimps ) by using measured recoil energies from direct dark matter detection experiments directly , it was assumed that the analyzed data sets are background
free , i.e. , all events are wimp signals . in this article , as a more realistic study , we take into account a fraction of possible residue background events , which pass all discrimination criteria and then mix with other real wimp induced events in our data sets .
our simulations show that , for the determination of the wimp mass , the maximal acceptable fraction of residue background events in the analyzed data sets of @xmath0 total events is @xmath1 20% , for background windows of the entire experimental possible energy ranges , or in low energy ranges ; while , for background windows in relatively higher energy ranges , this maximal acceptable fraction of residue background events can not be larger than @xmath1 10% . for a wimp mass of 100 gev with 20% background events in the windows of the entire experimental possible energy ranges ,
the reconstructed wimp mass and the 1@xmath2 statistical uncertainty are @xmath3 ( @xmath4 for background free data sets ) .
march 2010 * effects of residue background events in direct dark matter + detection experiments on the determination of the wimp mass * + yu - ting chou@xmath5 and chung - lin shan@xmath6 + @xmath7 _ institute of physics , national chiao tung university + no . 1001 , university road , hsinchu city 30010 , taiwan , r.o.c . _ + _ e - mail : _ [email protected] + + @xmath8 _ department of physics , national cheng kung university + no . 1 , university road , tainan city 70101 , taiwan , r.o.c . _ + _ e - mail : _
[email protected] + + @xmath9 _ physics division , national center for theoretical sciences + no . 101 , sec . 2 , kuang - fu road , hsinchu city 30013 , taiwan , r.o.c . _ .
And you have already written the first three sentences of the full article: currently , direct dark matter detection experiments searching for weakly interacting massive particles ( wimps ) are one of the promising methods for understanding the nature of dark matter and identifying them among new particles produced at colliders as well as reconstructing the ( sub)structure of our galactic halo @xcite . in order to determine the mass of halo wimps _ without _ making any assumptions about their density near the earth or their velocity distribution _ nor _ knowing their scattering cross section on nucleus , a model independent method by combining two experimental data sets with two different target nuclei has been developed @xcite .
this method builds on the earlier work on the reconstruction of the ( moments of the ) one dimensional velocity distribution function of halo wimps , @xmath10 , by using data from direct detection experiments @xcite . in the analysis of reconstructing @xmath10 ,
the moments of the wimp velocity distribution function can be determined from experimental data directly with an _ unique _.
Please generate the next two sentences of the article | input information about the wimp mass @xmath11 .
hence , one can simply require that the values of a given moment of @xmath10 determined by two experiments agree . |
8,271 | Suppose that you have an abstract for a scientific paper: the study presented in this paper shows that accounting for the relativistic structure of the deuteron allows to explain the ratio of the drell - yan pair production cross - section at the low bjorken @xmath0 off the deuteron and the proton .
thus , the sea quark distributions in the nucleon should be studied with accounting for the effects of the relativistic structure of the deuteron .
the suggested approach reduces theoretical uncertainty in extracting the ratio @xmath1 from the data and it is important for the clarification of the nature of the sea quark asymmetry in the nucleon . .
And you have already written the first three sentences of the full article: the drell - yan pair production remains up to now the theoretically cleanest way to access sea - quark distributions in hadrons .
necessary stage of such analysis is the measurement both with protons and neutrons , in which sea - quarks with different flavors are probed .
as the construction of a target containing free neutrons is not feasible , nuclear targets have to be employed . in the experiment that used the simplest nuclear target.
Please generate the next two sentences of the article | the deuteron , the flavor asymmetry of the sea - quark distributions in the nucleon has been observed @xcite . at the same time
, analysis of the deep inelastic scattering off different nuclei shows that nucleon valence quark structure changes beyond mass - shell @xcite . |
8,272 | Suppose that you have an abstract for a scientific paper: in recent years the experimental study of neutrino oscillations has much contributed to our knowledge of particle physics by establishing non vanishing neutrino masses and by measuring or constraining the corresponding mixing angles . within the domain of neutrino oscillations , the main goal of the next generation of facilities
is the measurement of the mixing angle @xmath0 and the observation of leptonic cp violation , for which we have no hints at the moment .
we discuss more in detail how various models of neutrino - nucleus cross section affect the forecasted precision measurement of @xmath0 and the cp violating phase @xmath1 @xcite .
+ _ contribution to nufact 11 , xiiith international workshop on neutrino factories , super beams and beta beams , 1 - 6 august 2011 , cern and university of geneva ( submitted to iop conference series ) _ .
And you have already written the first three sentences of the full article: in the quasi - elastic regime ( qe ) , the doubly - differential cross section , in which a neutrino carrying initial four - momentum @xmath2 scatters off a nuclear target to a state of four - momentum @xmath3 can be written in born approximation as follows : [ elem ] = l _ w_a^ , where @xmath4 is the fermi constant and @xmath5 is the ckm matrix element coupling @xmath6 and @xmath7 quarks .
the leptonic tensor is completely determined by lepton kinematics , whereas the nuclear tensor @xmath8 , containing all the information on strong interactions dynamics , describes the response of the target nucleus , @xmath9 where @xmath10 and @xmath11 are the initial and final hadronic states carrying four momenta @xmath12 and @xmath13 and @xmath14 is the nuclear electroweak current operator ; the sum includes all hadronic final states . in the impulse approximation ( ia ) scheme ,
the nuclear current can be written as a sum of one - body currents , i.e. @xmath15 , while the final state reduces to the direct product of the hadronic state produced at the weak vertex ( with momentum @xmath16 ) and that describing the @xmath17-nucleon residual system , with momentum @xmath18 : @xmath19 ..
Please generate the next two sentences of the article | following ref .
@xcite , the final expression of the hadronic tensor can be cast in the following form : w_a^&= & d^3pde p(*p*,e ) w^(p , q ) , [ hadtensor ] where @xmath20 and the function @xmath21 is the target _ spectral function _ |
8,273 | Suppose that you have an abstract for a scientific paper: we consider discrete - time ( dt ) systems s in which a dt input is first transformed to a continuous - time ( ct ) format by phase - amplitude modulation , then modified by a non - linear ct dynamical transformation f , and finally converted back to dt output using an ideal de - modulation scheme . assuming that f belongs to a special class of ct volterra series models with fixed degree and memory depth
, we provide a complete characterization of s as a series connection of a dt volterra series model of fixed degree and memory depth , and an lti system with special properties .
the result suggests a new , non - obvious , analytically motivated structure of digital compensation of analog nonlinear distortions ( for example , those caused by power amplifiers ) in digital communication systems .
we also argue that this baseband model , and its corresponding digital compensation structure , can be readily extended to ofdm modulation .
results from a matlab simulation are used to demonstrate effectiveness of the new compensation scheme , as compared to the standard volterra series approach .
* key words : * communication system nonlinearities , nonlinear systems , modeling , phase modulation , amplitude modulation .
And you have already written the first three sentences of the full article: [ cols= " < , < " , ] after fixing compensator structure , coefficients @xmath0 are obtained by applying straightforward least squares optimization .
+ we should emphasize here that fitting has to be done for both real and imaginary part of @xmath1 $ ] , thus the actual compensator structure is twice that depicted in figure [ fig : compensator_structure ] .
+ simulation parameters for system * s * are as follows : symbol rate @xmath2 , carrier frequency @xmath3 , with 64qam input symbol sequence ..
Please generate the next two sentences of the article | nonlinear distortion subsystem * f * of * s * , used in simulation , is defined in , where the delays @xmath4 are given by the vector @xmath5 $ ] , with @xmath6 .
digital simulation of the continuous part of * s * was done by representing continuous signals by their discrete counterparts , obtained by sampling with high sampling rate @xmath7 . |
8,274 | Suppose that you have an abstract for a scientific paper: the integrated brightness of the sun shows variability on time - scales from minutes to decades .
this variability is mainly caused by pressure mode oscillations , by granulation and by dark spots and bright faculae on the surface of the sun . by analyzing the frequency spectrum of the integrated brightness
we can obtain greater knowledge about these phenomena .
it is shown how the frequency spectrum of the integrated brightness of the sun in the frequency range from 100 to 3200 @xmath0hz shows clear signs of both granulation , faculae and p - mode oscillations and that the measured characteristic time - scales and amplitudes of the acoustic signals from granulation and faculae are consistent with high - resolution observations of the solar surface . using 13 years of observations of the sun s integrated brightness from the virgo instrument on the @xmath1 satellite
it is shown that the significance of the facular component varies with time and that it has a significance above 0.99 around half the time .
furthermore , an analysis of the temporal variability in the measured amplitudes of both the granulation , faculae and p - mode oscillation components in the frequency spectrum reveals that the amplitude of the p - mode oscillation component shows variability that follows the solar cycles , while the amplitudes of the granulation and facular components show signs of quasi - annual and quasi - biennial variability , respectively .
[ firstpage ] sun : faculae , plages sun : granulation sun : helioseismology sun : oscillations hz ) , the facular component ( around 1800 @xmath0hz ) and the p - mode oscillations component ( around 3000 @xmath0hz ) are seen as changes in the slope of the spectrum .
the different components are more clearly marked in fig .
2 .
it is also seen that the spectrum declines faster at frequencies higher than the p - mode oscillations or the atmospheric acoustic cut - off frequency .
the spectrum was calculated from 13 years of observations of the sun s....
And you have already written the first three sentences of the full article: the frequency spectrum of observations of the integrated brightness of the sun is often referred to as the solar acoustic spectrum @xcite , as it is mainly used to study pressure or sound waves inside the sun .
these sound waves can be observed on the surface of the sun as oscillation pattens which can be represented as spherical harmonics of the eigenfunctions of the sound waves inside the sun .
these sound waves lead to a series of distinct peaks in the solar acoustic spectrum ( see fig . 1 ) and by studying the frequencies , amplitudes and line - widths of these peaks we can through helioseismology obtain knowledge of the physics that takes place inside the sun ( see e.g. * ? ? ?.
Please generate the next two sentences of the article | * ) , but more information are hidden in the solar acoustic spectrum . at lower frequency
the solar acoustic spectrum contains signals from spots , granulation and faculae . |
8,275 | Suppose that you have an abstract for a scientific paper: we consider the computational complexity of hamiltonians which are sums of commuting terms acting on plaquettes in a square lattice of qubits , and we show that deciding whether the ground state minimizes the energy of each local term individually is in the complexity class .
that is , if the ground states has this property , this can be proven using a classical certificate which can be efficiently verified on a classical computer .
different to previous results on commuting hamiltonians , our certificate proves the existence of such a state without giving instructions on how to prepare it . .
And you have already written the first three sentences of the full article: understanding the ground state properties of spin systems on a lattice is of central importance in many - body physics , but at the same time , it is a highly challenging problem in many scenarios .
an important step in understanding its difficulty has been the insight that computing e.g. the ground state energy of a classical spin system is , in general , an complete problem @xcite : while the energy of any given spin configuration can be easily computed , finding the configuration with minimal energy is in general a difficult task it can be as hard as any problem in , i.e. , any problem whose solution can be efficiently verified . for quantum spin systems , an additional difficulty arises : generally , we can not even expect to have an efficient description of the ground state .
thus , it seems that the only statement we can make about the difficulty of the problem is that given a quantum register with the ground state , we will be able to efficiently estimate its energy using a quantum computer ..
Please generate the next two sentences of the article | indeed , it has been shown that this is the best we can say , as the problem of estimating the ground state energy of a quantum system is a complete problem for the class @xcite , the quantum analogue of : it contains all problems which have a quantum solution which can be efficiently checked on a quantum computer , and thus , determining the ground state energy of a quantum spin system is as hard as any of these problems ; in fact , the problem retains its hardness even when restricted to two - dimensional lattices of qubits with nearest - neighbor interactions @xcite or one - dimensional chains @xcite .
it is an interesting question to understand the reasons underlying the additional complexity of quantum spin systems as compared to classical systems . to this end , |
8,276 | Suppose that you have an abstract for a scientific paper: we study fusion reactions of the @xmath0ni+@xmath1sn system using the recently introduced density constrained time - dependent hartree - fock formalism . in this formalism
the fusion barriers are directly obtained from tdhf dynamics .
in addition , we incorporate the entrance channel alignment of the deformed ( oblate ) @xmath0ni nucleus due to dynamical coulomb excitation .
we discuss the influence of particle transfer and other dynamical effects on the fusion cross sections . calculated cross sections are in very good agreement with data and other calculations .
= 10000 = 10000 = 10000 .
And you have already written the first three sentences of the full article: with the increasing availability of radioactive ion - beams @xcite the study of structure and reactions of exotic nuclei has become feasible @xcite . in particular , detailed investigations of the fusion process
are crucial for the prediction of heavy - element formation and will lead to a better understanding of the interplay among the strong , coulomb , and weak interactions as well as the enhanced correlations present in these many - body systems .
recently , particular attention has been given to the @xmath0ni+@xmath1sn system , where a large sub - barrier fusion enhancement was observed @xcite ..
Please generate the next two sentences of the article | for this system fusion cross sections were measured in the energy range 142 mev @xmath2 195 mev .
in particular , it was found that fission is negligible for @xmath3 160 mev and therefore the evaporation residue cross sections have been taken as fusion cross sections . |
8,277 | Suppose that you have an abstract for a scientific paper: the main result presented here is that the flow associated with a riemannian metric and a non zero magnetic field on a compact oriented surface without boundary , under assumptions of hyperbolic type , can not have the same length spectrum of topologically corresponding periodic orbits as the geodesic flow associated with another riemannian metric having a negative curvature and the same total volume .
the main tool is a regularization inspired by u. hamenstdt s methods
. 30 pt universit de nantes , dpartement de mathmatiques , laboratoire jean leray u. m. r. 6629 , 2 , rue de la houssinire , bp 92208 , f-44322 nantes cedex 03 . [email protected] .
And you have already written the first three sentences of the full article: the problems of entropic and spectral rigidity of riemannian manifolds have been widely studied , beginning with the surfaces @xcite .
the works treat riemannian metrics on compact surfaces @xcite , @xcite , @xcite , on higher dimension manifolds @xcite , @xcite , @xcite , @xcite , or on surfaces with singularities @xcite .
the related problem of boundary rigidity of a riemannian metric features many results @xcite , @xcite , @xcite ..
Please generate the next two sentences of the article | the rigidity of an absolutely continuous flow conjugacy persists in some way with the presence of a magnetic field on a compact surface @xcite , and so do entropic rigidity in this case @xcite .
the topological entropy of the magnetic flow in higher dimension has also been studied @xcite , @xcite . unlike the geodesic flow , |
8,278 | Suppose that you have an abstract for a scientific paper: this paper investigates distributed angular frequency regulation of multi - machine power systems with wind generations when wind power signals frequencies are known ( and unknown ) .
the challenge is to regulate angular frequencies under fast changing and unpredictable wind generations . to address the issue
, we split unknown signals into three parts according to their frequency ranges and design an ( adaptive ) internal model to reconstruct the low and medium frequency parts .
we integrate heterogeneous grid components to deal with fast changing signals . at each bus with wind power generations , a battery energy storage system is used to filter out high frequency components of wind generations . at generator bus ,
demand response is utilized to deal with their medium frequency components and a synchronous generator is exploited to handle their low frequency components . at load bus ,
demand response handles low and medium frequency components .
the proposed controllers ensure exponential stability ( and asymptotic convergence ) of system states with respect to their desired signals .
simulations on the ieee 68-bus test system are conducted to demonstrate the effectiveness of the proposed controllers . and .
And you have already written the first three sentences of the full article: current power grid is being modernized into smart grid by enabling the integrations of advanced information and communication technologies relating power consumption and storage @xcite . integrating new technologies to power grid
enables us to control the grid in a more flexible and efficient manner .
for example , two - way communication and information technologies allow the use of demand response and automatic meter reading , respectively . another important feature is to merge variable renewable energy sources such as wind , solar , and wave energy generators to the grid ..
Please generate the next two sentences of the article | it is well known that renewable energy attracts more attentions due to its cleanness and profitability .
worldwide 144 countries now have their own political targets for increasing shares of renewable energy generations and especially european union targets 20% of renewable energy shares by 2020 @xcite |
8,279 | Suppose that you have an abstract for a scientific paper: we present numerical solutions of the gross pitaevskii equation corresponding to reconnecting vortex lines .
we determine the separation of vortices as a function of time during the approach to reconnection , and study the formation of pyramidal vortex structures .
results are compared with analytical work and numerical studies based on the vortex filament method . .
And you have already written the first three sentences of the full article: the discrete nature of vorticity in quantum fluids ( superfluid @xmath0he , @xmath1he and atomic bose
einstein condensates ) makes it possible to give physical meaning to vortex reconnections .
the importance of vortex reconnections in turbulence can not be overestimated ..
Please generate the next two sentences of the article | reconnections randomise the velocity field thus sustaining the turbulent vortex tangle in a steady state @xcite and changing the flow s topology @xcite . by triggering a kelvin wave cascade @xcite ,
reconnections are responsible for the decay of turbulent kinetic energy at very low temperatures @xcite . |
8,280 | Suppose that you have an abstract for a scientific paper: binary systems subject to generic perturbations evolve on quasiperiodic orbits .
we derive the most generic class of perturbations , which allow to evaluate secular effects via generalized complex true and eccentric anomaly parameters , by use of the residue theorem .
such perturbations include both the generic brumberg force and various linear contributions to the conservative dynamics of compact binaries , up to the second post - newtonian order . as an example , we compute the self - spin contribution to the luminosity due to gravitational radiation of a compact binary consisting of galactic black holes , the most important type of source for lisa .
this translates to simply calculate the residue of the instantaneous energy loss in the origin of the complex parameter plane , which illustrates the power of the presented method . .
And you have already written the first three sentences of the full article: the perturbed two - body problem is one of the central areas of interest of celestial mechanics .
a wide class of perturbations of the dynamics of a binary system are described by the generic brumberg force [ @xcite ] .
another type of perturbation is provided by general relativistic modifications of gravitational dynamics ..
Please generate the next two sentences of the article | such measurable effects arise in planetary motion ( like the general relativistic contribution to the precession of the perihelion of the planet mercury ) , however more important are the modifications in the strong - field regime , typically appearing in compact binaries composed of neutron stars and / or black holes .
a well - known example is the hulse - taylor double pulsar [ @xcite ] , the orbital period of which is continuously decreasing as gravitational radiation escapes from the system [ @xcite ] ( for a recent review see [ @xcite ] ) . |
8,281 | Suppose that you have an abstract for a scientific paper: we address the problem of heat transport in a chain of coupled quantum harmonic oscillators , exposed to the influences of local environments of various nature , stressing the effects that the specific nature of the environment has on the phenomenology of the transport process .
we study in detail the behavior of thermodynamically relevant quantities such as heat currents and mean energies of the oscillators , establishing rigorous analytical conditions for the existence of a steady state , whose features we analyze carefully .
in particular , we assess the conditions that should be faced to recover trends reminiscent of the classical fourier law of heat conduction and highlight how such a possibility depends on the environment linked to our system .
understanding the transport properties in open systems in contact with several energy or particle baths represents a challenge for nonequilibrium physics . ideally , one would like to characterize and even calculate explicitly the statistics of the energy and particle currents , similarly to what can be done with observables in ensembles at equilibrium
. however the properties of the currents in out - of - equilibrium systems depends strongly on the bath properties , and on the characteristics of the system - bath coupling . in this context
, chains of oscillators have been extensively used as microscopic models for heat conduction and , in general , for out - of - equilibrium systems @xcite to investigate the behavior of the thermal conductivity for different interaction potentials between the oscillators , different bath properties , or different system - bath couplings @xcite .
the fourier law of heat conduction implies that the heat current @xmath0 flowing throughout a system under a temperature gradient scales as the inverse of the system size @xmath1 , _
i.e. _ , @xmath2 . in the classical case
, it is known that this law is violated in 1d homogeneous harmonic systems @xcite where heat is carried by freely propagating elastic waves....
And you have already written the first three sentences of the full article: in this section we will consider a large class of systems with a generic number of degrees of freedom @xmath5 .
let us define the operator @xmath6 which is the column vector composed by @xmath5 generalized coordinates together with @xmath5 canonical conjugate momenta .
it is possible to express the canonical commutation relations involving coordinates and momenta compactly as @xmath7 = i \hbar \ , \mathsf j_{jk}$ ] with @xmath8 the elements of the symplectic matrix @xmath9 here @xmath10 and @xmath11 are the @xmath5 dimensional identity and zero matrix , respectively . in the remainder of these notes.
Please generate the next two sentences of the article | , we will be dealing with quadratically coupled harmonic oscillators . in this scenario ,
the use of first and second moments of @xmath12 provides a powerful tool for the description of the physically relevant quantities involved in the evolution of the system . |
8,282 | Suppose that you have an abstract for a scientific paper: using an atom interferometer , we have measured the static electric polarizability of @xmath0li @xmath1 m@xmath2 @xmath3 atomic units with a @xmath4% uncertainty .
our experiment , which is similar to an experiment done on sodium in 1995 by d. pritchard and co - workers , consists in applying an electric field on one of the two interfering beams and measuring the resulting phase - shift . with respect to d. pritchard s experiment ,
we have made several improvements which are described in detail in this paper : the capacitor design is such that the electric field can be calculated analytically ; the phase sensitivity of our interferometer is substantially better , near @xmath5 mrad/@xmath6 ; finally our interferometer is species selective so that impurities present in our atomic beam ( other alkali atoms or lithium dimers ) do not perturb our measurement .
the extreme sensitivity of atom interferometry is well illustrated by our experiment : our measurement amounts to measuring a slight increase @xmath7 of the atom velocity @xmath8 when it enters the electric field region and our present sensitivity is sufficient to detect a variation @xmath9 . .
And you have already written the first three sentences of the full article: the measurement of the electric polarizability @xmath10 of an atom is a difficult experiment : this quantity can not be measured by spectroscopy , which can access only to polarizability differences , and one should rely either on macroscopic quantity measurements such as the electric permittivity ( or the index of refraction ) or on electric deflection of an atomic beam . for a review on polarizability measurements , we refer the reader to the book by kresin and bonin @xcite . for alkali atoms ,
all the accurate experiments were based on the deflection of an atomic beam by an inhomogeneous electric field and , in the case of lithium , the most accurate previous measurement was done in 1974 by bederson and co - workers @xcite , with the following result @xmath11 m@xmath2 .
however , in 2003 , amini and gould , using an atomic fountain @xcite , have measured the polarizability of cesium atom with a @xmath12% relative uncertainty , which is presently the smallest uncertainty on the electric polarisability of an alkali atom ..
Please generate the next two sentences of the article | atom interferometry , which can measure any weak modification of the atom propagation , is perfectly adapted to measure the electric polarizability of an atom : this was demonstrated in 1995 by d. pritchard and co - workers @xcite with an experiment on sodium atom and they obtained a very high accuracy , with a statistical and systematic uncertainties both equal to @xmath13% .
this experiment was and remains difficult because an electric field must be applied on only one of the two interfering beams : one must use a capacitor with a thin electrode , a septum , which can be inserted between the two atomic beams . using our lithium atom interferometer @xcite , |
8,283 | Suppose that you have an abstract for a scientific paper: we present a study of the irregular dwarf galaxy holmberg ii based on pspc observations ( total exposure time : 22ksec ) .
holmberg ii is a nearby ( 3.2mpc ) , well studied dwarf irregular galaxy .
it is famous for its interstellar medium which is dominated by expanding structures such as hi holes and shells .
we search for x ray emission from point sources as well as for diffuse emission , down to the detection limit of the data . using x
ray hardness ratio diagrams we differentiate between thermal plasma and power law x ray spectra which helps to determine the nature of the individual sources . correlating the x ray data with complementary observations ranging from the far ultraviolet to the radio regime we increase the probability of correctly identifying sources belonging to holmberg ii .
we did not detect soft x
ray emission originating from hot gas within supergiant hi shells above our luminosity sensitivity limit of ( @xmath0@xmath1 ) .
this finding can probably be attributed to blow out in the case of the largest holes and insufficient sensitivity ( due to strong photoelectric absorption ) in case of the smaller hi holes . however we find faint x
ray sources well beyond the stellar body but within the hi distribution of holmberg ii , which suggests the presence of x ray binaries .
this indicates that star formation has taken place across the entire gaseous disk of holmberg ii in the past , some of which may have created the structures seen in the ism at large galactocentric radii . .
And you have already written the first three sentences of the full article: holmberg ii ( hereafter abbreviated as hoii ) is one of the most famous examples of a dwarf galaxy exhibiting a violent , disrupted ism , as traced by its appearance in the 21cm hi line @xcite .
hi holes are present across the entire galaxy even well beyond hoii s stellar body .
@xcite compiled a catalog of individual hi shells ..
Please generate the next two sentences of the article | the measured radial expansion velocities ( 10 - 25@xmath2 ) and diameters ( 1002000pc ) indicate that most of the holes are still expanding and have ages of @xmath3 to @xmath4yr .
hoii has been studied at many other wavelengths as well , such as radio continuum wavelengths @xcite , optical @xcite and fuv @xcite . besides |
8,284 | Suppose that you have an abstract for a scientific paper: we study the possibility of using w pair production and leptonic decay of one of the w s at the ilc with polarized beams as a probe of the littlest higgs model .
we consider cross - sections , polarization fractions of the w s , leptonic decay energy and angular distributions , and left - right polarization asymmetry as probes of the model .
with parameter values allowed by present experimental constraints detectable effects on these observables at typical ilc energies of 500 gev and 800 gev will be present .
beam polarization is further found to enhance the sensitivity . * w physics at the ilc with polarized beams as a probe of the littlest higgs model * + centre for high energy physics + indian institute of science + bangalore 560 012 , india + + department of physics + indian institute of technology guwahati + guwahati 781 039 , india + .
And you have already written the first three sentences of the full article: one of the important processes that will be studied at high precision at ilc with and without beam polarization is w - pair production .
phenomelonogical studies of this process within the standard model ( sm ) have been carried out in great detail @xcite .
since properties of the weak gauge bosons are closely linked to electroweak symmetry breaking ( ewsb ) and the structure of the gauge sector in general , detailed study of w physics will throw light on what lies beyond the sm ..
Please generate the next two sentences of the article | the study of mechanisms of ewsb is one of the main concerns of particle physics today .
the standard higgs mechanism is less than satisfactory , and faces difficulties such as the hierarchy problem . |
8,285 | Suppose that you have an abstract for a scientific paper: we study the inviscid multilayer saint - venant ( or shallow - water ) system in the limit of small density contrast .
we show that , under reasonable hyperbolicity conditions on the flow and a smallness assumption on the initial surface deformation , the system is well - posed on a large time interval , despite the singular limit . by studying the asymptotic limit
, we provide a rigorous justification of the widely used rigid - lid and boussinesq approximations for multilayered shallow water flows .
the asymptotic behaviour is similar to that of the incompressible limit for euler equations , in the sense that there exists a small initial layer in time for ill - prepared initial data , accounting for rapidly propagating `` acoustic '' waves ( here , the so - called barotropic mode ) which interact only weakly with the `` incompressible '' component ( here , baroclinic ) . .
And you have already written the first three sentences of the full article: this work dedicated to the study of the so - called multilayer saint - venant system , which arises as an approximate model for the propagation of waves in the ocean or atmosphere , when density stratification can not be neglected .
we will refer to as _ free surface system _ the following first - order , quasilinear system of @xmath0 coupled evolution equations : @xmath1 here , the unknowns @xmath2 and @xmath3 represent respectively the deformation of the @xmath4 interface and the layer - averaged horizontal velocity in the @xmath4 layer , at time @xmath5 and horizontal position @xmath6 where @xmath7 ; see figure [ f.sketchofthedomain ] . if @xmath8 , then we denote @xmath9 and @xmath10 .
we denote by @xmath11 the mass density of the homogeneous fluid in the @xmath4 layer , whereas @xmath12 is the gravitational acceleration ..
Please generate the next two sentences of the article | finally , @xmath13 is the depth of the @xmath4 layer . by convention
, we set @xmath14 ( above the upper free surface is vacuum ) , and @xmath15 ( the bottom is flat ) . |
8,286 | Suppose that you have an abstract for a scientific paper: we study topological recursion on the irregular spectral curve @xmath0 , which produces a weighted count of dessins denfant .
this analysis is then applied to topological recursion on the spectral curve @xmath1 , which takes the place of the airy curve @xmath2 to describe asymptotic behaviour of enumerative problems associated to irregular spectral curves . in particular , we calculate all one - point invariants of the spectral curve @xmath1 via a new three - term recursion for the number of dessins denfant with one face . .
And you have already written the first three sentences of the full article: _ topological recursion _
developed by eynard , orantin and chekhov produces invariants of a riemann surface @xmath3 equipped with two meromorphic functions @xmath4 and a bidifferential @xmath5 for @xmath6 @xcite .
we require the zeros of @xmath7 to be simple and refer to the data @xmath8 as a _.
Please generate the next two sentences of the article | spectral curve_. for integers @xmath9 and @xmath10 , the invariant @xmath11 is a multidifferential on @xmath3 or , in other words , a tensor product of meromorphic 1-forms on @xmath12 . in this paper ,
all spectral curves will have underlying riemann surface @xmath13 and bidifferential @xmath14 . in that case |
8,287 | Suppose that you have an abstract for a scientific paper: we analyze a mechanism of coupling of high- and low-@xmath0 bands in terms of a dynamical treatment for nuclear rotations , i.e.,wobbling motion .
the wobbling states are produced through the generator coordinate method after angular momentum projection ( _ gcm - after - amp _ ) , in which the intrinsic states are constructed through fully self - consistent calculations by the 2d - cranked ( or tilted - axis - cranked ) hfb method . in particular , the phenomena of `` signature inversion '' and `` signature splitting '' in the t - band ( tilted rotational band ) are explained in terms of the wobbling model .
our calculations will be compared with new data for in - band e2 transition rates in @xmath1os , which may shed light on the mechanism of the anomalous @xmath2 isomer decay , directly to the yrast band . .
And you have already written the first three sentences of the full article: in the @xmath3 region of the rare - earth nuclei , three bands are observed to interact with each other at @xmath4 .
the bands are g- , s- and t - bands . the g- and
s - bands are well - known rotational bands of the ground state and rotation - aligned configurations , respectively . on the other hand ,.
Please generate the next two sentences of the article | the t - band means `` tilted - rotating '' band which was proposed by frauendorf @xcite . in @xmath5os ,
the t - band has a @xmath6 band head , while @xmath1os has @xmath7 . |
8,288 | Suppose that you have an abstract for a scientific paper: we present a simple model to describe the lowest - subbands surface scattering in locally oxidized silicon nanowires grown in the [ 110 ] direction . to this end
, we employ an atomistically scaled effective mass model projected from a three - dimensional effective mass equation and apply a quantum transport formalism to calculate the conductance for typical potential profiles .
comparison of our results with hole - transport calculations using atomistic models in conjuction with density functional theory ( dft ) points to an intra - subband scattering mechanism from a potential well .
drouvelis and fagas : scattering model for locally oxidized si nanowires intraband scattering , silicon nanowires , oxidation .
And you have already written the first three sentences of the full article: recent bottom - up @xcite and top - down @xcite demonstrations of si channels with diameters of only a few nanometers shape the roadmap towards the ultimate limits of scaling . silicon nanowires ( sinws ) , in particular , can be easily integrated with existing semiconductor technologies . as experimental results
remain difficult to obtain and analyze at this lengthscale , modelling has a crucial role to play in assessing this technology .
owing to computational and methodological advances , great progress has been achieved in atomic - scale transport calculations , first in molecular systems @xcite and later in semiconductor nanowires @xcite ..
Please generate the next two sentences of the article | nevertheless , semiconductor physics is most easily captured within the effective mass theory and many device simulators are built based on this approximation @xcite .
this implies that simple models describing the basic mechanisms are required @xcite . |
8,289 | Suppose that you have an abstract for a scientific paper: the generation of spin current and spin polarization in a 2deg structure is studied in the presence of dresselhaus and rashba spin - orbit couplings ( soc ) , the strength of the latter being modulated in time by an ac gate voltage . by means of the non - abelian gauge field approach , we established the relation between the lorentz spin force and the spin current in the soc system , and showed that the longitudinal component of the spin force induces a transverse spin current . for a constant ( time - invariant ) rashba system ,
we recover the universal spin hall conductivity of @xmath0 , derived previously via the berry phase and semiclassical methods . in the case of a time - dependent soc system ,
the spin current is sustained even under strong impurity scattering .
we evaluated the ac spin current generated by a time - modulated rashba soc in the absence of any dc electric field .
the magnitude of the spin current reaches a maximum when the modulation frequency matches the larmor frequency of the electrons . .
And you have already written the first three sentences of the full article: the generation of a sustained spin polarized current constitutes a key requirement in practical spintronics . in two - dimensional electron gas ( 2deg )
systems with rashba spin - orbit coupling ( soc ) , spin precession about the rashba field and the accompanying zitterbewegung - like motion would usually result in zero net transverse spin current on average.@xcite however , a net spin polarization can be generated in the transverse direction via the spin hall effect .
based on the time - gauge field @xcite or the semi - classical geometric force @xcite descriptions , it can be shown that a vertical ( out - of - plane ) spin polarization can be sustained under adiabatic conditions , albeit under ballistic limit only ..
Please generate the next two sentences of the article | other methods of generating spin current which have been proposed include the application of a non - uniform external magnetic field in a soc medium @xcite and the use of optical excitation.@xcite recently , an all - electrical method has been also investigated by utilizing a time - varying gate voltage.@xcite the idea is based on the fact that the rashba soc can be tuned by changing the applied gate voltage.@xcite however , it is pointed out that , in the rashba system , only the in - plane polarized spin currents are generated.@xcite therefore , it would be interesting if the out - of - plane polarized component of the spin current can be generated by applying this method . in this article , we will present a theoretical study of the spin current generation in 2deg system that combines both time - dependent rashba and dresselhauss socs . in frame work of non - abelian gauge field
, we will point out that time - modulated gate voltage can indeed induce a spin current polarized in the out - of - plane direction of the 2deg . |
8,290 | Suppose that you have an abstract for a scientific paper: one of the primary goals when studying stellar systems with neutron stars has been to reveal the physical properties of progenitors and understand how neutron star spins and birth kicks are determined . over the years
a consensus understanding had been developed , but recently some of the basic elements of this understanding are being challenged by current observations of some binary systems and their theoretical interpretation . in what follows we review such recent developments and
highlight how they are interconnected ; we particularly emphasize some of the assumptions and caveats of theoretical interpretations and examine their validity ( e.g. , in connection to the unknown radial velocities of pulsars or the nuances of multi - dimensional statistical analysis ) .
the emerging picture does not erase our earlier understanding ; instead it broadens it as it reveals additional pathways for neutron star formation and evolution : neutron stars probably form at the end of both core collapse of fe cores of massive stars and electron - capture supernovae of onemg cores of lower - mass stars ; birth kicks are required to be high ( well in excess of 100kms@xmath0 ) for some neutron stars and low ( @xmath1kms@xmath0 ) for others depending on the formation process ; and spin up may occur not just through roche - lobe overflow but also through wind accretion or phases of hypercritical accretion during common envelope evolution .
address = northwestern university , department of physics and astronomy , 2131 tech drive , evanston , il 60208 , usa address = northwestern university , department of physics and astronomy , 2131 tech drive , evanston , il 60208 , usa address = northwestern university , department of physics and astronomy , 2131 tech drive , evanston , il 60208 , usa .
And you have already written the first three sentences of the full article: forty years after the discovery of pulsars it is fair to say that an immense amount of progress has been made in the quest to understand how neutron stars ( ns ) form and evolve in different stellar systems .
our understanding of these processes has benefited most importantly by the study of binary pulsars or x - ray binaries harboring ns with either stellar or degenerate companions ( white dwarfs or other ns ) .
progress has been made both by studying specific observed systems as well as whole populations in the galactic field or in globular clusters.these analyses and results have always coupled strongly to efforts in the areas of core - collapse and supernova ( sn ) explosions of massive stars , thermonuclear explosions of accreting white dwarfs , and nuclear evolution of massive stars . through this diverse body of work (.
Please generate the next two sentences of the article | for which it is impossible to include here all important references , but relevant overviews may be found in @xcite ) a generally accepted understanding seemed to have emerged anchored on the following crucial elements most relevant to the discussion presented in this paper : ( i ) ns form at the end of stellar nuclear evolution as remnants of sn explosions of massive stars of @xmath2m@xmath3 up to @xmath4m@xmath3 ; ( ii ) ns in close binaries typically have helium - rich progenitors at the time of core collapse ; these progenitors are the helium - rich cores ( typically more massive than 2m@xmath3 ) of original massive binary companions which have lost their hydrogen - rich envelopes through binary interactions involving ( stable or unstable ) mass transfer between binary components and/or mass loss from the binary ; ( iii ) at the time of their formation ns acquire recoil kicks due to asymmetries that develop during the core - collapse process ; typical kick magnitudes inferred from studies of pulsar population kinematics and the formation of binaries with ns are in the range of 100300kms@xmath0 ; ( iv ) ns are born with birth spin periods of @xmath5ms and spin down over a time span of @xmath2myr ; if in binaries they can spin up and reach spin periods of 10ms or shorter later in their life through accretion of material from their companion and accompanied reduction in magnetic - field strength . in recent years a growing number of ns studies have challenged different aspects of the `` standard picture '' as described above .
although each one of these in isolation may not have been powerful enough to cause a paradigm shift , the current set of inter - linked arguments presented in the literature in the past @xmath6 years has certainly attracted attention and has opened the door to potential changes in our current understanding of how ns form . |
8,291 | Suppose that you have an abstract for a scientific paper: we consider the dynamical evolution of bound , hierarchical triples of supermassive black holes that might be formed in the nuclei of galaxies undergoing sequential mergers . the tidal force of the outer black hole on the inner binary produces eccentricity oscillations through the kozai mechanism , and
this can substantially reduce the gravitational wave merger time of the inner binary .
we numerically calculate the merger time for a wide range of initial conditions and black hole mass ratios , including the effects of octupole interactions in the triple as well as general relativistic periastron precession in the inner binary .
the semimajor axes and the mutual inclination of the inner and outer binaries are the most important factors affecting the merger time .
we find that for a random distribution of inclination angles and approximately equal mass black holes , it is possible to reduce the merger time of a near circular inner binary by more than a factor of ten in over fifty percent of all cases .
we estimate that a typical exterior quadrupole moment from surrounding matter in the galaxy may also be sufficient to excite eccentricity oscillations in supermassive black hole binaries , and also accelerate black hole mergers . .
And you have already written the first three sentences of the full article: the ubiquity of supermassive black holes ( smbhs ) in the nuclei of many galaxies ( e.g. magorrian et al .
1998 ) suggests that binary and multiple smbh systems may also be widespread .
for example , smbh binaries should form in galaxy mergers ( begelman , blandford , & rees 1980 ) , which is a common process in hierarchical models for galaxy formation and evolution ( e.g. kauffmann & haehnelt 2000 ; menou , haiman , & narayanan 2001 ) ..
Please generate the next two sentences of the article | smbh binaries have been invoked to explain periodic wiggles in extragalactic radio jets ( e.g. roos , kaastra , & hummel 1993 ) , periodic flares in the bl lac source oj 287 ( e.g. lehto & valtonen 1996 ) , variations in the apparent superluminal transverse velocities and position angles of the 3c 273 radio jet ( romero et al .
2000 ) , and the `` core - type '' nuclear surface brightness profiles of bright elliptical galaxies ( ebisuzaki , makino , & okumura 1991 ; quinlan & hernquist 1997 ; faber et al . |
8,292 | Suppose that you have an abstract for a scientific paper: by using a constituent quark model we compute the form factors relevant to semileptonic transitions of b mesons into low - lying @xmath0-wave charmed mesons .
we evaluate the @xmath1 dependence of these form factors and compare them with other model calculations . the isgur - wise functions @xmath2 and @xmath3 are also obtained in the heavy quark limit of our results . .
And you have already written the first three sentences of the full article: recently , babar collaboration has discovered a narrow state with @xmath4 with a mass of 2317 mev , @xmath5 @xcite .
the existence of a second narrow resonance , @xmath6 with @xmath7 , was confirmed by cleo @xcite .
both states have been confirmed by belle @xcite . soon after the discovery , another set of charmed mesons , @xmath8 and @xmath9 which have the same quantum numbers @xmath10 as @xmath11 has been discovered by belle @xcite . before their discovery ,.
Please generate the next two sentences of the article | quark model and lattice calculations predicted that the masses of these states , in particular @xmath5 and @xmath12 , would be significantly higher than observed @xcite,@xcite .
moreover , these states were predicted to be broad due to the fact that they can decay into @xmath13 and @xmath14 , respectively . |
8,293 | Suppose that you have an abstract for a scientific paper: we develop a new unified theoretical approach enabling us to non - perturbatively study the effect of electron - electron interactions on weak localization in arbitrary arrays of quantum dots .
our model embraces ( i ) weakly disordered conductors ( ii ) strongly disordered conductors and ( iii ) metallic quantum dots . in all these cases at @xmath0 the electron decoherence time is determined by the universal formula @xmath1 , where @xmath2 , @xmath3 , @xmath4 and @xmath5 are respectively dimensionless conductance , dwell time , charging energy and level spacing of a single dot . in the case ( i )
this formula yields @xmath6 ( @xmath7 is the diffusion coefficient ) and matches with our previous quasiclassical results [ d.s .
golubev , a.d .
zaikin , phys .
rev .
lett .
81 ( 1998 ) 1074 ] , while in the cases ( ii ) and ( iii ) it illustrates new physics not explored earlier .
a detailed comparison between our theory and numerous experiments provides an overwhelming evidence that zero temperature electron decoherence in disordered conductors is universally caused by electron - electron interactions rather than by magnetic impurities . , weak localization , decoherence , electron - electron interactions , disorder , quantum dots 73.63.kv , 73.21.la , 73.20.fz , 73.23.-b .
And you have already written the first three sentences of the full article: quantum interference of electrons in mesoscopic conductors manifests itself in a number of fundamentally important phenomena which can be directly observed in modern experiments .
one of them is the phenomenon of weak localization ( wl ) @xcite . in the absence of interactions
electron wave functions preserve their coherence and , hence , quantum interference remains efficient throughout a large part of the sample making wl a pronounced effect ..
Please generate the next two sentences of the article | interactions between electrons and with other degrees of freedom may limit phase coherence thereby making quantum interference of electrons possible only within a finite length scale @xmath8 .
this so - called electron decoherence length as well as directly related to it decoherence time @xmath9 ( where @xmath7 is diffusion coefficient ) are crucial parameters indicating importance of quantum effects in the system under consideration . at sufficiently high temperatures quantum behavior of electrons in disordered conductors |
8,294 | Suppose that you have an abstract for a scientific paper: the recently discovered chimera state involves the coexistence of synchronized and desynchronized states for a group of identical oscillators .
this fascinating chimera state has until now been found only in non - local or globally coupled oscillator systems . in this work ,
we for the first time show numerical evidence of the existence of spiral wave chimeras in reaction - diffusion systems where each element is _ locally _ coupled by diffusion .
this spiral wave chimera rotates inwardly , i.e. , coherent waves propagate toward the phase randomized core .
a continuous transition from spiral waves with smooth core to spiral wave chimeras is found as we change the local dynamics of the system .
our findings on the spiral wave chimera in locally coupled oscillator systems largely improve our understanding of the chimera state and suggest that spiral chimera states may be found in natural systems which can be modeled by a set of oscillators indirectly coupled by a diffusive environment . .
And you have already written the first three sentences of the full article: collective behavior , which occurs commonly in physical , chemical and biological systems , has been a subject of continued interest in nonlinear science over the last decades @xcite . in neural and biological systems , a typical collective behavior observed is the coherent motion of oscillators .
this phenomenon of synchronization has been widely regarded as having important implications to the function and performance of those systems @xcite .
for instance , asynchronous contraction of the heart the may be triggered by electrical spiral waves , which eventually leads to heart dysfunction @xcite ..
Please generate the next two sentences of the article | recently , much attention has been paid to a particular hybrid state in which an ensemble of identical oscillators with identical coupling spontaneously degenerate to one group with synchronization ( coherent ) and the other group with desynchronization ( incoherent ) @xcite .
this fascinating counterintuitive state was first discovered by kuramoto and co - workers @xcite , and named chimera state " by strogatz @xcite . |
8,295 | Suppose that you have an abstract for a scientific paper: the fibonomial triangle has been shown by chen and sagan to have a fractal nature mod 2 and 3 .
both these primes have the property that the fibonacci entry point of @xmath0 is @xmath1 .
we study the fibonomial triangle mod 5 , showing with a theorem of knuth and wilf that the triangle has a recurring structure under divisibility by five .
while this result is not new , our method of proof is new and suggests a conjecture for the divisibility of a fibonomial coefficient by a general prime @xmath0 .
we give necessary conditions for such primes , namely that the fibonacci entry point must be greater than or equal to @xmath0 , and offer numerical evidence for the validity of the conjecture .
lastly , we conclude with a discussion concerning further directions of research . .
And you have already written the first three sentences of the full article: pascal s triangle is constructed from binomial coefficients @xmath2 , where @xmath3 is the @xmath4 entry of the @xmath5 row ( see figure [ pastri ] ) .
it is well - known that pascal s triangle exhibits a fractal nature mod @xmath0 where @xmath0 is a prime . for example , in the mod 2 case , the triangle follows the pattern of sierpinski s fractal , the fractal which begins with a triangle and removes the center quarter , doing the same for each remaining upright triangle at each iteration , as in figure [ sieriter ] .
@xmath6 one can correlate each iteration of sierpinski s fractal to the first @xmath7 rows of pascal s triangle mod 2 , where the `` removed '' portion is all the zeros mod 2 , that is , all the even numbers ..
Please generate the next two sentences of the article | the first 8 rows of this triangle , corresponding to the second iteration of sierpinski s fractal , are shown in figure [ pascal2 ] .
@xmath8 beyond @xmath9 , the exact fractal produced mod @xmath0 is different than sierpinski s , but exhibits the same repetitive structure . |
8,296 | Suppose that you have an abstract for a scientific paper: we consider ( closed neighbourhood ) packings and their generalization in graphs called limited packings .
a vertex set @xmath0 in a graph @xmath1 is a _ @xmath2-limited packing _
if for any vertex @xmath3 , @xmath4 \cap x\right| \le k$ ] , where @xmath5 $ ] is the closed neighbourhood of @xmath6 .
the _ @xmath2-limited packing number _
@xmath7 is the largest size of a @xmath2-limited packing in @xmath1 .
limited packing problems can be considered as secure facility location problems in networks .
we develop probabilistic and greedy approaches to limited packings in graphs , providing lower bounds for the @xmath2-limited packing number , and randomized and greedy algorithms to find @xmath2-limited packings satisfying the bounds .
some upper bounds for @xmath7 are given as well .
the problem of finding a maximum size @xmath2-limited packing is known to be @xmath8-complete even in split or bipartite graphs . .
And you have already written the first three sentences of the full article: we consider simple undirected graphs , and are interested in the classical packings of graphs as introduced in @xcite , and their generalization , called limited packings , as presented in @xcite . in the literature , the classical packings can be referred to under different names , e.g. , as ( distance ) @xmath9-packings @xcite , closed neighborhood packings @xcite , or strong stable sets @xcite .
they can also be considered as generalizations of independent ( stable ) sets , which would be ( distance ) @xmath10-packings , following the terminology of @xcite .
a vertex set @xmath0 in a graph @xmath1 is a.
Please generate the next two sentences of the article | _ @xmath2-limited packing _
if for any vertex @xmath3 , @xmath4 \cap x\right| \le k$ ] , where @xmath5 $ ] is the closed neighbourhood of @xmath6 . |
8,297 | Suppose that you have an abstract for a scientific paper: the idea of sensitivity in ant colony systems has been exploited in hybrid ant - based models with promising results for many combinatorial optimization problems .
heterogeneity is induced in the ant population by endowing individual ants with a certain level of sensitivity to the pheromone trail .
the variable pheromone sensitivity within the same population of ants can potentially intensify the search while in the same time inducing diversity for the exploration of the environment .
the performance of sensitive ant models is investigated for solving the generalized vehicle routing problem .
numerical results and comparisons are discussed and analysed with a focus on emphasizing any particular aspects and potential benefits related to hybrid ant - based models .
ant - based models , optimization , sensitivity , complex problems .
And you have already written the first three sentences of the full article: the potential of ant - based models @xcite in solving difficult optimization problems has been well emphasized by successful results obtained in many and varied fields including transportation optimization , quadratic assignment , scheduling , vehicle routing and protein folding .
inspired by the real - world collective behaviour of social insects , _ ant colony system ( acs ) _
algorithms @xcite rely on the stigmergic interactions between many identical artificial ants to find solutions to a given problem ..
Please generate the next two sentences of the article | each ant generates a complete tour ( associated to a problem solution ) by probabilistically choosing the next node at each path intersection based on the cost and the amount of pheromone on the connecting edge .
stronger pheromone trails are preferred and the most promising tours build up higher amounts of pheromone in time . inducing heterogeneity in the population by enabling each artificial ant to react in a different way to the same environment @xcite represents a promising approach to the application of ant - based models for solving complex real - world problems possibly with a dynamic character . |
8,298 | Suppose that you have an abstract for a scientific paper: natural and artificial light harvesting systems often operate in a regime where the flux of photons is relatively low . besides absorbing as many photons as possible
it is therefore paramount to prevent excitons from annihilation via photon re - emission until they have undergone an irreversible energy conversion process .
taking inspiration from photosynthetic antenna structures , we here consider ring - like systems and introduce a class of states we call ratchets : excited states capable of absorbing but not emitting light .
this allows our antennae to absorb further photons whilst retaining the excitations from those that have already been captured .
simulations for a ring of four sites reveal a peak power enhancement by up to a factor of 35 under ambient conditions owing to a combination of ratcheting and the prevention of emission through dark - state population . in the slow extraction limit the achievable power enhancement due to ratcheting alone exceeds 20% . _ introduction _ the absorption of light and prevention of its reemission is essential for the efficient operation of solar energy harvesting devices @xcite . from the many causes of device inefficiency ,
few are as fundamental and seemingly insurmountable as energy loss via radiative recombination : any absorption process must have a companion emission process .
this inherent absorption inefficiency is a result of the principle of ` detailed balance ' and constitutes a key contribution to the famous shockley - queisser limit @xcite .
however , pioneering work by scully showed that it is possible to break detailed balance , given an external source of coherence @xcite ; later work showed that this can be achieved by clever internal design alone , by using an optically dark state to prevent exciton recombination @xcite .
such dark states are populated passively if the energy separation between dark and bright states falls into the vibrational spectrum of the absorbing nanostructure : dissipation then preferentially mediates....
And you have already written the first three sentences of the full article: the jordan - wigner transformation maps a pauli spin 1/2 system onto a ` hard - core ' boson model @xcite .
this leads to a bosonic description of the collective excitons whilst maintaining pauli s exclusion principle , which forbids double excitation of a single site . in our case
each ` spin ' represents one of @xmath0 identical optical emitters / absorbers and the spin s ` up ' / ` down ' projection along the @xmath86-axis denotes the presence / absence of an exciton on the respective site ..
Please generate the next two sentences of the article | we assume a ring - like geometrical arrangement as shown in fig .
1a of the main paper . |
8,299 | Suppose that you have an abstract for a scientific paper: making use of public spectra from cimatti et al .
( 2008 ) , we measure for the first time the velocity dispersion of spheroid - like massive ( @xmath0@xmath1 ) galaxies at @xmath2 . by comparing with galaxies of similar stellar mass at lower redshifts
, we find evidence for a mild evolution in velocity dispersion , decreasing from @xmath3kms@xmath4 at @xmath2 down to @xmath5kms@xmath4 at @xmath6 .
such mild evolution contrasts with the strong change in size ( a factor of @xmath7 ) found for these type of objects in the same cosmic time , and it is consistent with a progressive larger role , at lower redshift , of the dark matter halo in setting the velocity dispersion of these galaxies .
we discuss the implications of our results within the context of different scenarios proposed for the evolution of these massive objects . .
And you have already written the first three sentences of the full article: recent observations show that the most massive ( @xmath8@xmath1 ) spheroid - like galaxies at @xmath9 , irrespective of their star formation activity ( prez - gonzlez et al .
2008 ) , were much smaller ( a factor of @xmath7 ) than their local counterparts ( daddi et al . 2005 ; trujillo et al . 2006 , 2007 ; longhetti et al . 2007
; zirm et al . 2007 ; toft et al . 2007 ;.
Please generate the next two sentences of the article | giavalisco et al .
2007 ; ravindranath et al . |
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