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11,400 |
Suppose that you have an abstract for a scientific paper: a group is simphatic if it acts geometrically on a simply connected simplicially hereditarily aspherical ( simphatic ) complex .
we show that finitely presented normal subgroups of simphatic groups are either : * finite , or * of finite index , or * virtually free .
this result applies , in particular , to normal subgroups of systolic groups .
we prove similar strong restrictions on group extensions for other classes of asymptotically aspherical groups .
the proof relies on studying homotopy types at infinity of groups in question .
in appendix we present the topological @xmath0dimensional quasi - helly property of systolic complexes . .
And you have already written the first three sentences of the full article: _ systolic complexes _ were introduced for the first time by chepoi @xcite under the name _ bridged complexes_. they were defined there as flag simplicial completions of _ bridged graphs _
@xcite the latter appear naturally in many contexts related to metric properties of graphs and , in particular , convexity .
systolic complexes were rediscovered by januszkiewicz- ' swiatkowski @xcite and haglund @xcite , independently , in the context of geometric group theory ..
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namely , _ systolic groups _ ,
that is , groups acting geometrically on systolic complexes have been used to construct important new examples of highly dimensional gromov hyperbolic groups
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11,401 |
Suppose that you have an abstract for a scientific paper: we extend recent theoretical results on the propagation of linear gravitational waves ( gws ) , including their associated memories , in spatially flat friedmann lematre robertson walker ( flrw ) universes , for all spacetime dimensions higher than 3 . by specializing to a cosmology driven by a perfect fluid with a constant equation - of - state @xmath0 conformal re - scaling , dimension - reduction and nariai s ansatz
may then be exploited to obtain analytic expressions for the graviton and photon green s functions , allowing their causal structure to be elucidated .
when @xmath1 , the gauge - invariant scalar mode admits wave solutions , and like its tensor counterpart , must therefore contribute to the tidal squeezing and stretching of the space around a gw detector .
we identify potential 4-dimensional ( 4d ) scalar gw memory effects that propagate on its acoustic - cone " .
in addition , scalar gws in 4d radiation dominated universes like tensor gws in 4d matter dominated ones appear to yield a tail - induced memory effect that does not decay with increasing spatial distance from the source .
we then solve electromagnetism in the same cosmologies , and point out a similar tail - induced electric memory effect .
finally , in even dimensional minkowski backgrounds higher than 2 , we make a brief but explicit comparison between the linear gw memory generated by point masses scattering off each other on unbound trajectories and the linear yang - mills memory generated by color point charges doing the same and point out how there is a
double copy " relation between the two . .
And you have already written the first three sentences of the full article: humanity has , after several decades of effort , finally achieved the direct detection of gravitational waves @xcite .
given that we expect to detect gravitational wave ( gw ) events from astrophysical systems located at cosmological distances even the first two events , gw150914 and gw151226 , were produced at non - trivial redshifts @xmath2 it is desirable to examine from first principles how gws propagate over cosmological spacetimes , by solving einstein s equations perturbatively about the background spatially flat friedmann
lematre robertson walker ( flrw ) universe we reside in ..
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such a strategy is to be contrasted against the asymptotically flat spacetime calculations from which gw observables are usually extracted . to be very scrupulous when predicting gw events at cosmological distances , as already pointed out in @xcite , one has to match the ` far zone ' predictions of these asymptotically flat calculations onto a near / intermediate zone cosmological one , before evolving the wave solutions out to infinity
furthermore , one may also wonder if these gws journeying over a size - able fraction of our observable universe could experience the expansion of space itself , as well as interact with the intervening inhomogeneities thereby picking up additional features that could in turn provide us with novel probes of dark energy and dark matter . in this paper
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11,402 |
Suppose that you have an abstract for a scientific paper: we present new photometric observations of egand , zand , bfcyg , chcyg , cicyg , v1329cyg , txcvn , agdra , rwhya , agpeg , axper , ivvir and the peculiar m giant v934her , which were made in the standard johnson @xmath0 system .
qwsge was measured in the kron - cousin @xmath1 system and for arpav we present its new visual estimates .
the current issue gathers observations of these objects to december 2003 .
the main results can be summarized as follows : * egand * : the primary minimum in the @xmath2 light curve ( lc ) occurred at the end of 2002 .
a 0.2 0.3mag brightening in @xmath2 was detected in the autumn of 2003 .
* zand * : at around august 2002 we detected for the first time a minimum , which is due to eclipse of the active object by the red giant .
measurements from 2003.3 are close to those of a quiescent phase .
* bfcyg * : in february 2003 a short - term flare developed in the lc .
a difference in the depth of recent minima was detected .
* chcyg * : this star was in a quiescent phase at a rather bright state .
a shallow minimum occurred at @xmath3jd 2452730 , close to the position of the inferior conjunction of the giant in the inner binary of the triple - star model of chcyg .
* cicyg * : our observations cover the descending branch of a broad minimum .
* txcvn * : at / around the beginning of 2003 the star entered a bright stage containing a minimum at @xmath3jd 2452660 . *
agdra * : new observations revealed two eruptions , which peaked in october 2002 and 2003 at @xmath39.3 in @xmath2 . * arpav * : our new visual estimates showed a transient disappearance of a wave - like modulation in the star s brightness between the minima at epochs e = 66 and e = 68 and its reappearance . * agpeg * : our measurements from the end of 2001 showed rather complex profile of the lc . *
rwhya * : observations follow behaviour of the wave - like variability of quiet symbiotics . *
axper * : in may 2003 a 0.5mag flare was detected following a rapid decrease of the light to a....
And you have already written the first three sentences of the full article: the symbiotic stars are currently understood as interacting binary systems consisting of a cool giant and a hot compact star , which is in most cases a white dwarf .
typical orbital periods are between 1 and 3 years , but they can be significantly larger . the mass loss from the giant represents the primary condition for appearance of the symbiotic phenomenon .
a part of the material lost by the giant is transferred to the more compact companion via accretion from the stellar wind or roche - lobe overflow ..
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this process generates a very hot ( @xmath5k ) and luminous ( @xmath6 ) source of radiation . on the basis of the way in which the generated energy is being liberated , we distinguish two phases of symbiotic binary . _ quiescent phases _ during which the hot component releases its energy approximately at a constant rate and spectral distribution
generally , we observe a wave - like variation in their lcs as a function of the orbital phase . during _ active phases _ the hot component radiation changes significantly , which leads to a 2 - 3mag brightening of the object in the optical .
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11,403 |
Suppose that you have an abstract for a scientific paper: we present the results of our analysis on charmonia ( @xmath0 and @xmath1 ) hadroproduction taking into account higher - order qcd effects induced by initial - state radiation in a monte carlo framework , with the colour - octet mechanism implemented in the event generation .
we find that those colour - octet matrix elements extracted so far from fermilab tevatron data for both @xmath0 and @xmath1 production have to be lowered significantly .
we finally make predictions for charmonia production at the lhc , presenting a simple code for a _ fast _ simulation with pythia based on the colour - octet model .
= -.5 cm = 0.cm = 0.cm = 22.cm = 15.6 cm // + : quarkonia production ; color - octet ; nrqcd ; lhc ; tevatron .
And you have already written the first three sentences of the full article: likely , the large hadron collider or lhc will become operative by the beginning of the next century , offering a wide programme of exciting possibilities in particle physics , among which the origin of mass at the electroweak scale and the possible discovery of supersymmetric particles , the investigation of cp violation in b mesons and detailed studies of top quark physics . other interesting topics related to charm and beauty flavours will be covered as well benefitting of a foreseen huge statistics to be collected with the machine running even at @xmath2low " luminosity ( @xmath3 @xmath4 ) @xcite @xcite . following this line of research
, we shall focus in this paper on inclusive hadroproduction of heavy resonances , in particular charmonia @xmath0 and @xmath1 states , whose relevance in the study of perturbative and non - perturbative qcd will be briefly reviewed .
to first approximation , heavy - flavour hadroproduction can be treated in the framework of perturbative qcd due to the relatively large quark masses @xcite and consequently the partonic production cross sections can be convoluted with parton distribution functions ( pdf s ) of the colliding protons ..
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this scheme can indeed be viewed as well founded since the underlying parton interaction is hard , therefore providing a reasonable justification for such a factorization of the production process .
higher - order corrections to the matrix elements of the short - distance processes may be incorporated likely improving the accuracy of the predicted cross sections .
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11,404 |
Suppose that you have an abstract for a scientific paper: this paper describes the security weaknesses of a recently proposed secure communication method based on chaotic masking using projective synchronization of two chaotic systems .
we show that the system is insecure and how to break it in two different ways , by high - pass filtering and by generalized synchronization . , , , and .
And you have already written the first three sentences of the full article: in recent years , a considerable effort has been devoted to extend the chaotic communication applications to the field of secure communications .
the possibility of synchronization of two coupled chaotic systems was first shown by pecora and carrol @xcite and opened the possibility of using the signals generated by chaotic systems as carriers for analog and digital communications .
this discovery soon aroused great interest as a potential means for secure communications @xcite ..
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accordingly , a great number of cryptosystems based on chaos have been proposed @xcite , some of them fundamentally flawed by a lack of robustness and security @xcite .
projective synchronization ( ps ) is an interesting phenomena firstly described by mainieri and rehacek @xcite , it consists in the synchronization of two partially linear coupled chaotic systems , master and slave , in which the amplitude of the slave system is a scalar multiple , called scaling factor , of that of the master system in the phase space .
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11,405 |
Suppose that you have an abstract for a scientific paper: we present a comparison of the leftover satellites at z=0 in a cold dark matter dominated simulation of the formation of the local group to the distribution of observed neutral hydrogen high - velocity clouds and compact high - velocity clouds .
the @xmath02000 leftover satellites in the simulation have dark matter masses which range between 0.5 to 10 @xmath1 , sizes between 3 to 30 kpc , and distances between 100 kpc and 2 mpc .
the dark matter halos show a clear bias in their distribution towards m31 and to a lesser extent towards the local group anti - barycenter .
if the local group halos contain @xmath01% of their dark matter mass in neutral hydrogen they should have been easily detected by the current surveys .
the only objects detected with the potential to be the local group halos are the high - velocity clouds . here
the spatial , kinematic , and flux properties of the clouds and dark matter halos are compared .
several different subsets of halos which may be more likely to contain neutral hydrogen are investigated , and the hvcs are found to have some similar properties to those halos within 500 kpc of the galaxy and those halos with dark matter masses @xmath2 .
the compact high - velocity clouds do not show similar properties to the halos .
# 1_#1 _ # 1_#1 _ = # 1 1.25 in .125 in .25 in .
And you have already written the first three sentences of the full article: the distribution of neutral hydrogen in the universe is largely traced by the ly@xmath3 forest , ly - limit systems , damped ly@xmath3 systems and galaxies , but the relationship between these tracers remains unknown .
the predicted existence of a large number of individual dark matter halos in groups of galaxies by the cold dark matter ( cdm ) models of the formation of galaxies and clusters may provide a clue to the link between these features .
if the excess satellites / halos exist , do they trace the distribution of the group and explain the abundance and location of the absorbers ?.
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all - sky hi surveys have detected only one type of object which could be the abundance of dark matter halos scattered throughout the local group .
these are the high - velocity clouds ( hvcs ) . using a standard cdm model of the formation of the local group ( moore et al .
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11,406 |
Suppose that you have an abstract for a scientific paper: -4.5 cm pitha 03/04 , hep - ph/0308040 , 27 june 2003 3.8 cm i estimate the su(3 ) flavour symmetry breaking in the ratio of penguin - to - tree ratios of the decays @xmath0 and @xmath1 , given an assumption on the flavour symmetry breaking of the hadronic input parameters .
the decay amplitudes are calculated in qcd factorization .
implications for the determination of @xmath2 are discussed . .
And you have already written the first three sentences of the full article: in this note i perform a study of su(3 ) breaking for the decays @xmath1 and @xmath0 .
this system is interesting , because it allows for a determination of the angle @xmath2 from mixing - induced and direct cp asymmetries @xcite provided the su(3 ) symmetry breaking corrections to a certain double ratio of amplitudes are known .
the analysis of su(3 ) breaking is done in the theoretical framework of qcd factorization @xcite , which expresses the hadronic decay amplitudes in terms of fundamental constants , decay constants , form factors etc . in the heavy quark limit ..
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the following is a preliminary version of work in progress in collaboration with m. neubert .
we write the decay amplitudes as @xmath3 where @xmath4 .
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11,407 |
Suppose that you have an abstract for a scientific paper: a strategy to evaluate the distribution of the largest schmidt eigenvalue for entangled random pure states of bipartite systems is proposed .
we point out that the multiple integral defining the sought quantity for a bipartition of sizes @xmath0 is formally identical ( upon simple algebraic manipulations ) to the one providing the probability density of landauer conductance in open chaotic cavities supporting @xmath1 and @xmath2 electronic channels in the two leads .
known results about the latter can then be straightforwardly employed in the former problem for both systems with broken ( @xmath3 ) and preserved ( @xmath4 ) time reversal symmetry .
the analytical results , yielding a continuous but not everywhere analytic distribution , are in excellent agreement with numerical simulations . .
And you have already written the first three sentences of the full article: consider two sets of @xmath5 correlated random variables in @xmath6 $ ] , @xmath7 and @xmath8 ( @xmath9 ) , respectively distributed according to the following joint probability densities ( jpd ) : @xmath10 where @xmath11 and @xmath12 are known normalization constants and @xmath13 . in the following two subsection we will provide physical motivations for considering such sets , namely set @xmath14 corresponds to the distribution of schmidt eigenvalues for entangled random pure states in bipartite systems ( see subsection [ ent ] ) , while set @xmath15 corresponds to the distribution of transmission eigenvalues of an open cavity in the chaotic regime ( see subsection [ condcav ] ) .
consider now the following statistical quantities : * the cumulative distribution @xmath16 $ ] of the largest member of set @xmath14 , @xmath17 . by definition , this is given by the following @xmath5-fold integral : @xmath18^n}d\lambda_1\cdots d\lambda_n \mathcal{p}_1(\lambda_1,\ldots,\lambda_n)\ ] ] differentiating @xmath19 , one obtains the _ probability density _ of @xmath20 , p_n(x)=q_n(x)[densq ] * the probability density @xmath21 $ ] of the quantity @xmath22 , which is given by the following @xmath5-fold integral : . ]
@xmath23^n}dt_1\cdots dt_n \mathcal{p}_2(t_1,\ldots , t_n)\delta\left(y-\sum_{i=1}^n t_i\right)\ ] ] simple algebraic manipulations , summarized in appendix [ appa ] lead to the following relation between the two quantities above : @xmath24 the identity in eq ..
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is the main result of this paper will be discussed in detail later on . ] . notwithstanding its remarkable simplicity , eq
actually permits an exact evaluation of @xmath19 , the so far unavailable distribution of the largest schmidt eigenvalue for _ finite _ @xmath5 ( see subsection [ ent ] ) , in terms of @xmath25 ( the probability density of landauer conductance , see subsection [ condcav ] ) about which much more is known .
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11,408 |
Suppose that you have an abstract for a scientific paper: hubble space telescope observations of active asteroid 324p / la sagra near perihelion show continued mass loss consistent with the sublimation of near - surface ice .
isophotes of the coma measured from a vantage point below the orbital plane are best matched by steady emission of particles having a nominal size @xmath0 100 @xmath1 m .
the inferred rate of mass loss , @xmath20.2 kg s@xmath3 , can be supplied by sublimation of water ice in thermal equilibrium with sunlight from an area as small as 930 m@xmath4 , corresponding to about 0.2% of the nucleus surface .
observations taken from a vantage point only 0.6 from the orbital plane of 324p set a limit to the velocity of ejection of dust in the direction perpendicular to the plane , @xmath5 1 m s@xmath3 .
short - term photometric variations of the near - nucleus region , if related to rotation of the underlying nucleus , rule out periods @xmath6 3.8 hr and suggest that rotation probably does not play a central role in driving the observed mass loss .
we estimate that , in the previous orbit , 324p lost about 4@xmath710@xmath8 kg in dust particles , corresponding to 6@xmath710@xmath9 of the mass of a 550 m spherical nucleus of assumed density @xmath10 = 1000 kg m@xmath11 . if continued , mass loss at this rate would limit the lifetime of 324p to @xmath121.6@xmath710@xmath13 orbits ( about 10@xmath14 yr ) . to survive for the 100 myr to 400 myr timescales corresponding , respectively , to dynamical and collisional stability
requires a duty cycle @xmath15 .
unless its time in orbit is over - estimated by many orders of magnitude , 324p is revealed as a briefly - active member of a vast population of otherwise dormant ice - containing asteroids . .
And you have already written the first three sentences of the full article: the active asteroids are solar system bodies which have asteroid - like orbits but which also show transient , comet - like activity .
evidence amassed over the past decade shows that this activity results from a remarkably broad range of physical processes , including impact , thermal fracture , rotational instabilities and ice sublimation .
identification of these processes in the main - belt represents a scientific watershed , by revealing diverse asteroid processes that were previously unobserved ( hsieh and jewitt 2006 , jewitt 2012 , jewitt et al ..
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2015 ) .
324p / la sagra ( formerly 2010 r2 and hereafter `` 324p '' ) is one of four active asteroids for which mass - loss has been reported on different orbits ( the others are 133p / elst - pizarro , 238p / read and 313p / gibbs ; jewitt et al .
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11,409 |
Suppose that you have an abstract for a scientific paper: we use numerical simulations to investigate effect of turbulent velocity on the power spectrum of intensity from external galaxies when ( a ) all emission is considered , ( b ) emission with velocity range smaller than the turbulent velocity dispersion is considered .
we found that for case ( a ) the intensity fluctuation depends directly only on the power spectrum of the column density , whereas for case ( b ) it depends only on the turbulent velocity fluctuation .
we discuss the implications of this result in real observations of fluctuations . physical data and process : turbulence - galaxy : disc - galaxies : ism .
And you have already written the first three sentences of the full article: observationally , power spectrum of the intensity fluctuation in our galaxy suggest existence of scale invariant structures in the density over length scales ranging as wide as sub parsec to a few hundred parsec .
these structures are understood in terms of compressible fluid turbulence in the interstellar medium ( ism ) . in present theoretical understanding of ism dynamics
, compressible fluid turbulence plays an important role in the ism evolution , energy transfer , star formation etc ..
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possible source of energy into the turbulence cascade is however debated , though is mostly ascribed to the supernova shocks as a large scale energy input .
different techniques have been developed to measure the velocity spectrum of the turbulence and hence infer the energy involved in the process .
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11,410 |
Suppose that you have an abstract for a scientific paper: the measure of the distances and luminosities of gamma - ray bursts ( grbs ) led to the discovery that many grb properties are strongly correlated with their intrinsic luminosity , leading to the construction of reliable luminosity indicators .
these grb luminosity indicators have quickly found applications , like the construction of pseudo - redshifts , or the measure of luminosity distances , which can be computed independently of the measure of the redshift . in this contribution
i discuss various issues connected with the construction of luminosity - redshift indicators for gamma - ray bursts .
[ 1999/12/01 v1.4c il nuovo cimento ] .
And you have already written the first three sentences of the full article: measuring the cosmological redshifts of gamma - ray bursts of all types ( grbs , xrfs , short - hard bursts ) is crucial for our understanding of these events .
the measure of redshifts tells us the energy output of the source , it allows the measure of the burst intrinsic parameters ( duration , peak energy etc ... ) , and determines the position of the burster in the history of the universe .
unfortunately , the obtention of spectroscopic redshifts requires a succession of non trivial observing steps : reliable localization of the prompt emission in x - rays or gamma - rays , quick distribution of the alert to the ground , identification of the afterglow at optical , radio or x - ray wavelenths , and measure of the redshift of the host galaxy in absorption ( when the afterglow is bright ) or in emission ( when the afterglow has faded ) ..
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this complex sequence of events explains why in february 2005 , 8 years after the discovery of the first afterglow , the web page of jochen greiner contains only 40 spectroscopic redshifts among 263 localized grbs ( of which about 100 have an optical , x - ray or radio afterglow ) .
the statistics is similar for hete-2 grbs @xcite , which has localized 75 events , from which 25 afterglows have been found , and 14 redshifts measured .
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11,411 |
Suppose that you have an abstract for a scientific paper: in the first semester calculus course we learn how to solve optimization problems such as maximizing the volume of a box or a can given its surface area , i.e. the amount of material , or minimizing the surface area given the desired volume .
whether you are a student or a teacher , have you ever wished you knew the answer to a problem after one glance at it , without doing long calculations ?
the patterns shown and explained below will enable you to do it for a few `` standard '' problems , but more excitingly , they will illustrate some very beautiful problem solving techniques and give insights into how different areas of mathematics are connected . .
And you have already written the first three sentences of the full article: it can be shown using the standard calculus optimization technique that of all rectangles with a given perimeter , the square has the largest area .
( it also follows that of all rectangles with a given area , the square has the smallest perimeter . )
there is also an easy geometric way to prove this ..
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the picture below shows two rectangles : one of them , @xmath0 , is a square , and the other , @xmath1 , is not .
they have the same perimeter ( @xmath2 ) , but the square has a larger area since the areas of the shaded parts are equal , but the square also contains a region that the other rectangle does not .
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11,412 |
Suppose that you have an abstract for a scientific paper: recently discovered quasi periodic oscillations in the x - ray brightness of low mass x - ray binaries are used to derive constraints on the mass of the neutron star component and the equation of state of neutron star matter .
the observations are compared with models of rapidly rotating neutron stars which are calculated by means of an exact numerical method in full relativity . for the equations of state we select a broad collection of models representing different assumptions about the many - body structure and the complexity of the composition of super dense matter .
the mass constraints differ from their values in the approximate treatment by @xmath0 % . under the assumption that the maximum frequency of the quasi periodic oscillations originates from the innermost stable orbit the mass of the neutron star is in the range : @xmath1 .
especially the quasi periodic oscillation in the atoll - source 4u1820 - 30 is only consistent with equations of state which are rather stiff at high densities which is explainable , so far , only with pure nucleonic / leptonic composition .
this interpretation contradicts the hypothesis that the protoneutron star formed in sn 1987a collapsed to a black hole , since this would demand a maximum neutron star mass below @xmath2 .
the recently suggested identification of quasi periodic oscillations with frequencies around 10 hz with the lense - thirring precession of the accretion disk is found to be inconsistent with the models studied in this work , unless it is assumed that the first overtone of the precession is observed .
stars : neutron equation of state gravitation stars : rotation accretion , accretion discs x - ray : stars .
And you have already written the first three sentences of the full article: neutron stars contain matter in one of the densest forms found in the universe .
their central density ranges from a few time the density of normal nuclear matter to about one order of magnitude higher , depending on the star s mass and the equation of state ( eos ) .
neutron stars therefore provide us with a powerful tool for exploring the properties of such dense matter . in the last decades ,.
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this tool was applied to , among other topics , the determination of the eos of dense , charge neutral , @xmath3-equilibrated matter by means of comparing the theoretical predicted properties with observations of neutron stars .
this was attempted by studying , for example , the maximum stable star mass @xcite , the minimum rotation period @xcite , or the thermal behaviour ( tsuruta 1966 , schaab et al .
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11,413 |
Suppose that you have an abstract for a scientific paper: we present an analysis of the neutrino oscillation solutions of the solar and atmospheric neutrino problems in the framework of four neutrino mixing where a sterile neutrino is added to the three standard ones and the mass spectra presents two separated doublets .
such scenarios allow for simultaneous transitions of solar @xmath0 , as well as atmospheric @xmath1 , into active and sterile neutrinos controlled by the additional mixing angles @xmath2 and @xmath3 , and they contain as limiting cases the pure solar @xmath0active and @xmath0sterile neutrino oscillations , and the pure atmospheric @xmath4 and @xmath5 oscillations , respectively .
we evaluate the allowed active sterile admixture in both solar and atmospheric oscillations from the combined analysis .
our results show that , although the super kamiokande data disfavour both the pure @xmath4 atmospheric channel and the pure @xmath6 solar channel , the result from the combined analysis still favours close to pure active and sterile oscillations and disfavours oscillations into a near maximal active sterile admixture . .
And you have already written the first three sentences of the full article: super kamiokande high statistics data @xcite indicate that the observed deficit in the @xmath7-like atmospheric events is due to the neutrinos arriving at the detector at large zenith angles , strongly suggestive of the @xmath1 oscillation hypothesis .
similarly , their data on the zenith angle dependence and recoil energy spectrum of solar neutrinos @xcite in combination with the results from homestake @xcite , sage @xcite , and gallex+gno @xcite experiments , have put on a firm observational basis the long standing problem of solar neutrinos , strongly indicating the need for @xmath0 conversions .
in addition to the solar and atmospheric neutrino results from underground experiments , there is also the indication for neutrino oscillations in the @xmath8 channel by the lsnd experiment @xcite ..
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all these results can be accommodated in a single oscillation framework only if there are at least three different scales of neutrino mass - squared differences .
the simplest case in which this condition is satisfied requires the existence of a fourth light neutrino , which must be _ sterile _ ( _ i.e. _ having interactions with standard model particles much weaker than the sm weak interaction ) in order not to affect the invisible @xmath9 decay width , precisely measured at lep @xcite .
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11,414 |
Suppose that you have an abstract for a scientific paper: in this paper , we analyze the celebrated em algorithm from the point of view of proximal point algorithms .
more precisely , we study a new type of generalization of the em procedure introduced in and called kullback - proximal algorithms .
the proximal framework allows us to prove new results concerning the cluster points .
an essential contribution is a detailed analysis of the case where some cluster points lie on the boundary of the parameter space . .
And you have already written the first three sentences of the full article: the problem of maximum likelihood ( ml ) estimation consists of finding a solution of the form @xmath0 where @xmath1 is an observed sample of a random variable @xmath2 defined on a sample space @xmath3 and @xmath4 is the log - likelihood function defined by @xmath5 defined on the parameter space @xmath6 , and @xmath7 denotes the density of @xmath2 at @xmath1 parametrized by the vector parameter @xmath8 .
the expectation maximization ( em ) algorithm is an iterative procedure which is widely used for solving ml estimation problems . the em algorithm was first proposed by dempster , laird and rubin and has seen the number of its potential applications increase substantially since its appearance .
the book of mclachlan and krishnan gives a comprehensive overview of the theoretical properties of the method and its applicability ..
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the convergence of the sequence of em iterates towards a maximizer of the likelihood function was claimed in the original paper but it was later noticed that the proof contained a flaw .
a careful convergence analysis was finally given by wu @xcite based on zangwill s general theory @xcite ; see also .
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11,415 |
Suppose that you have an abstract for a scientific paper: the pinning of vortex lines by an array of nanoparticles embedded inside superconductors has become the most efficient practical way to achieve high critical currents . in this situation
pinning occurs via trapping of the vortex - line segments and the critical current is determined by the typical length of the trapped segments . to verify analytical estimates and develop a quantitative description of strong pinning
, we numerically simulated isolated vortex lines driven through an array of nanoparticles .
we found that the critical force grows roughly as the square root of the pin density and it is strongly suppressed by thermal noise .
the configurations of pinned lines are strongly anisotropic , displacements in the drive directions are much larger than in the transverse direction .
moreover , we found that the roughening index for the longitudinal displacements exceeds one .
this indicates that the local stresses in the critical region increase with the total line length and the elastic description breaks down in the thermodynamic limit .
thermal noise reduces the anisotropy of displacements in the critical regions and straightens the lines . .
And you have already written the first three sentences of the full article: the introduction of large - size nanoparticles of different shapes has emerged as the best practical way to improve the current performance of high - temperature superconductors . while in the first superconducting cables
the critical currents were limited by weak links , in the second - generation superconducting wires based on aligned yba@xmath0cu@xmath1o@xmath2 ( ybco ) films this problem has been mostly resolved and critical currents are determined by vortex pinning .
impressive progress has been made to enhance critical currents in these films using both isotropic @xcite and columnar @xcite inclusions . in spite of this progress ,.
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our understanding of strong pinning mechanisms is far from satisfactory .
theoretical estimates describing the pinning of vortex lines by an array of strong pins at low temperatures were elaborated by ovchinnikov and ivlev.@xcite this theory was applied to describe the behavior of the critical currents in the real ybco films in refs .. in particular , frequently observed power - law decay of the critical current as a function of the magnetic field with a power slightly larger than @xmath3 is naturally explained by this theory .
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11,416 |
Suppose that you have an abstract for a scientific paper: balmer spectra are investigated which are obtained from hydrogen droplets irradiated by ultra - short intense laser pulses .
a unified quantum statistical description of bremsstrahlung , the stark broadening and the van der waals profile of hydrogen spectral lines is used , which allows to include many - particle effects . analyzing the line profiles , a low ionization degree of a dense plasma is inferred , where the main contribution to the spectral line shape originates from the interaction with the neutral components .
effective temperatures and densities of the radiating microplasma are deduced .
a dynamical description is given within plasma hydrodynamics , explaining the formation of excited atomic states in the expanding system and the occurrence of the observed balmer lines only below a critical density . .
And you have already written the first three sentences of the full article: spectroscopy is one of the most powerful methods in plasma diagnostics . in particular
, the analysis of the shape of spectral lines allows to determine the properties of the plasma such as temperature , density , and composition . for dense ,
strongly coupled plasmas , optical spectra have been investigated to infer the parameter values not only of laboratory , but also of astrophysical plasmas , see , e.g. refs ..
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@xcite and refs .
@xcite , respectively .
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Suppose that you have an abstract for a scientific paper: we report on measurements of three - body recombination loss rates in an ultracold gas of @xmath0li atoms in the extremely nonuniversal regime where the two - body scattering length vanishes .
we show that the loss rate coefficient is well defined and can be described by two - body parameters only : the scattering length @xmath1 and the effective range @xmath2 .
we find the rate to be energy independent , and , by connecting our results with previously reported measurements in the universal limit , we cover the behavior of the three - body recombination rate in the whole range from weak to strong two - body interactions . we identify a nontrivial magnetic field value in the nonuniversal regime where the rate should be suppressed .
the few - body problem underlies fundamental processes in physics , yet it is notoriously difficult for finding analytic and numerical solutions @xcite .
it challenges our mind with the complexity of small and system - dependent molecular structures at the size of their interaction potentials . at the same time , in the regime of resonant pairwise interactions , it provides an elegant description of unusually large bound states possessing universal properties .
two important two - body length scales are involved in this description .
the first is the van der waals length @xmath3 , which is constant and connected to the radial range of the potential .
the second is the @xmath4-wave scattering length @xmath1 , which can be tuned magnetically via a feshbach resonance @xcite .
when @xmath5 , universal two - body states with size @xmath6 emerge , and a wealth of phenomena known as efimov physics is opened up in three- and , generally , @xmath7-body sectors .
the fundamental states belonging to the efimov effect ( efimov trimers ) depend log - periodically on @xmath8 @xcite .
sufficiency of two - body parameters in the efimov scenario indicates that two - body physics plays a decisive role in the universal few - body processes in ultracold gases .
the....
And you have already written the first three sentences of the full article: the energy evolution in the time dependent optical dipole trap can be expressed as follows @xcite : @xmath91 where @xmath92 is the truncation parameter with @xmath93 being the truncation energy and @xmath94 stands for the energy carried away by the evaporated atom in addition to @xmath95 . in an harmonic trap
, @xmath94 can be evaluated analytically @xcite : @xmath96 where @xmath97 is the incomplete @xmath52 function . the first term in the right hand of eq .
( [ eq : energyev ] ) describes evaporation cooling ..
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generally , evaporation in the optical trap is accompanied by weakening of the trapping confinement , thus causing additional adiabatic cooling which is accounted for by the second term in eq .
( [ eq : energyev ] ) . the depth of the optical dipole potential is reduced exponentially in time : @xmath98 with the time constant @xmath99 defined by the ratio of initial and final potential depths : @xmath100 accordingly , the temporal behaviour of the trap s oscillation frequency is : @xmath101 with @xmath102 being the geometric mean of the initial oscillation frequencies .
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Suppose that you have an abstract for a scientific paper: we explore an analytic model of the accretion shock in the post bounce phase of a core - collapse supernova explosion .
we find growing oscillations of the shock in the @xmath0 and @xmath1 modes , in agreement with a variety of existing numerical simulations . for modest values of the ratio of the outer accretion shock to that of the inner boundary to the shocked flow , the instability appears to derive from the growth of trapped sound waves , whereas at higher values , postshock advection clearly plays a role .
thus the model described here may relate to the different mechanisms of instability recently advocated by blondin & mezzacappa , and by foglizzo and collaborators . .
And you have already written the first three sentences of the full article: there is a growing consensus that a large fraction of core - collapse supernovae , possibly including the whole subset of type ib / c events , undergo significantly asymmetrical explosions . while clearly rotation and magnetic fields may play some role in this , instability associated with the stalled shock that forms at a radius of 100 - 300 km and lasts for a few hundred microseconds post bounce offers the intriguing possibility of generating asymmetrical explosions from a symmetrical progenitor , since such instability is usually dominated by low mode @xmath0 , 2 oscillations of the shock front .
the original speculation for the origin of such oscillations @xcite in terms of convection behind the shock , following @xcite has been revised in recent years .
@xcite demonstrate that post shock advection can stabilize convective instability ( @xcite only deals with a static case ) , and that convection alone can not produce the dominant @xmath0,2 modes . in adiabatic simulations of gas with polytropic index 4/3 , which as shown by @xcite is a good description of shocked inner regions of a core - collapse supernova ,.
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@xcite were the first to associate the instability with the shock itself .
@xcite attributed this to the growth of trapped sound waves , travelling essentially laterally around the central accretor .
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Suppose that you have an abstract for a scientific paper: we consider a class of liquid crystal free - boundary problems for which both the equilibrium shape and internal configuration of a system must simultaneously be determined , for example in films with air- or fluid - liquid crystal interfaces and elastomers .
we develop a finite element algorithm to solve such problems with dynamic mesh control , achieved by supplementing the free energy with an auxiliary functional that promotes mesh quality and is minimized in the null space of the energy .
we apply this algorithm to a flexible capacitor , as well as to determine the shape of liquid crystal tactoids as a function of the surface tension and elastic constants .
these are compared with theoretical predictions and experimental observations of tactoids from the literature . .
And you have already written the first three sentences of the full article: surface effects are of fundamental importance in liquid crystal physics@xcite . chemical and topographical treatments induce a preferred molecular orientation that , due to elasticity , tends to align the material in the bulk .
patterned surfaces produce a wealth of phenomena , including multistable alignment@xcite and arbitrary control of the alignment orientation and associated anchoring energy@xcite .
highly confined liquid crystals , in channels , emulsion droplets , or polymer dispersed systems are also strongly influenced by the interaction of the lc material with the adjacent medium . as liquid crystals are deployed beyond display applications@xcite , the exploration of their behavior in complex geometries has become increasingly important ..
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almost ubiquitously , the shape of their enclosure is regarded as a rigid body and the equilibrium configuration of the liquid crystal found by minimizing an appropriate energy functional , a challenging enough task given the multiple competing physical effectselasticity , surfaces , applied and internal fieldsinvolved .
if the external environment is not rigid , the minimization problem also requires solving for the shape of the body .
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Suppose that you have an abstract for a scientific paper: the influence of geometry and morphology of superconducting structure on critical currents and magnetic flux trapping in percolative type - ii superconductor is considered .
the superconductor contains the clusters of a normal phase , which act as pinning centers .
it is found that such clusters have significant fractal properties .
the main features of these clusters are studied in detail : the cluster statistics is analyzed ; the fractal dimension of their boundary is estimated ; the distribution of critical currents is obtained , and its peculiarities are explored .
it is examined thoroughly how the finite resolution capacity of the cluster geometrical size measurement affects the estimated value of fractal dimension .
the effect of fractal properties of the normal phase clusters on the electric field arising from magnetic flux motion is investigated in the case of an exponential distribution of cluster areas .
the voltage - current characteristics of superconductors in the resistive state for an arbitrary fractal dimension are obtained .
it is revealed that the fractality of the boundaries of the normal phase clusters intensifies the magnetic flux trapping and thereby raises the critical current of a superconductor . .
And you have already written the first three sentences of the full article: an important property of the clusters of a normal phase in superconductor consists in their capability to trap a magnetic flux . by virtue of their capacity to hold the vortices from moving under the action of the lorentz force , such clusters can act as effective pinning centers @xcite-@xcite .
this feature is used widely in the making new composite superconducting materials of high current - carrying capability @xcite , @xcite .
the morphological characteristics of clusters of a normal phase exert an appreciable effect on magnetic flux dynamics in superconductors , especially when the clusters have fractal boundaries @xcite-@xcite . in the present work the geometric probability properties of such fractal clusters.
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are considered in detail , and their influence on the dynamics of trapped magnetic flux and critical currents is analyzed .
the further consideration will be concerned with the superconductor containing inclusions of a normal phase , which are out of contact with one another .
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Suppose that you have an abstract for a scientific paper: we have developed a straw tube chamber with pickup - pad readout .
the mechanism for signal pickup , the size of the pickup signal , and the distribution of signals among neighboring pads are discussed .
we have tested a prototype chamber in a beamtest at brookhaven national laboratory and have measured chamber efficiencies in excess of 99% . .
And you have already written the first three sentences of the full article: in this paper we describe the construction and performance of a straw tube chamber with a unique type of readout : rather than signals being read from anode wires , signals are read from pads placed against the straw tubes which pick up signals induced by the gas avalanches .
this readout scheme has three advantages : _ ( 1 ) _ fully - correlated @xmath0 and @xmath1 position information ; _ ( 2 ) _
the pad sizes can be chosen almost arbitrarily , for example , to give equal pad occupancy over a region in which particle flux is varying ; and _ ( 3 ) _.
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the high - voltage and front - end electronics are decoupled . for the gas avalanche signals to be picked up by the pads
, the straw tube material must be resistive such that the straw tube wall does not substantially shield the signal .
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Suppose that you have an abstract for a scientific paper: we have developed a low - cost off - the - shelf component star sensor ( _ starsense _ ) for use in minisatellites and cubesats to determine the attitude of a satellite in orbit .
_ starsense _ is an imaging camera with a limiting magnitude of 6.5 , which extracts information from star patterns it records in the images .
the star sensor implements a centroiding algorithm to find centroids of the stars in the image , a geometric voting algorithm for star pattern identification , and a quest algorithm for attitude quaternion calculation . here
, we describe the software package to evaluate the performance of these algorithms as a star sensor single operating system .
we simulate the ideal case where sky background and instrument errors are omitted , and a more realistic case where noise and camera parameters are added to the simulated images .
we evaluate such performance parameters of the algorithms as attitude accuracy , calculation time , required memory , star catalog size , sky coverage , etc . , and estimate the errors introduced by each algorithm .
this software package is written for use in matlab .
the testing is parametrized for different hardware parameters , such as the focal length of the imaging setup , the field of view ( fov ) of the camera , angle measurement accuracy , distortion effects , etc . , and
therefore , can be applied to evaluate the performance of such algorithms in any star sensor . for its hardware implementation on our
_ starsense _ , we are currently porting the codes in form of functions written in c. this is done keeping in view its easy implementation on any star sensor electronics hardware . .
And you have already written the first three sentences of the full article: an attitude / orientation control system is necessary for all satellites with different satellites requiring varying degrees of pointing accuracy .
satellites with a high - gain directional antenna , a telescope , or an earth - imaging instrument as payloads require highly accurate ( few arcminutes or arcseconds ) pointing system . determining
the current pointing position is of primary importance in such applications and it is usually achieved using star sensors : a wide - fov camera with online image processing capabilities which reduces the image data to an attitude quaternion that describes the rotation of the sensor coordinate system with respect to the earth - centered inertial ( eci ) coordinate system ..
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this is achieved by applying multiple algorithms on the image in sequence @xcite .
we have developed a low - cost star sensor _
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Suppose that you have an abstract for a scientific paper: previously , we proposed a model of low energy affleck - dine leptogenesis in the context of thermal inflation . the lepton asymmetry is generated at the end of thermal inflation , which occurs at a relatively low energy scale with the hubble parameter somewhere in the range @xmath0 .
thus hubble damping will be ineffective in bringing the affleck - dine field into the lepton conserving region near the origin , leaving the possibility that the lepton number could be washed out .
previously , we suggested that preheating could damp the amplitude of the affleck - dine field allowing conservation of the lepton number . in this paper , we demonstrate numerically that preheating does efficiently damp the amplitude of the affleck - dine field and that the lepton number is conserved as the result .
in addition to demonstrating a crucial aspect of our model , it also opens the more general possibility of low energy affleck - dine baryogenesis . .
And you have already written the first three sentences of the full article: the origin of the observed baryon asymmetry is a fundamental question in modern cosmology .
forty years ago sakharov showed that three conditions must be satisfied to generate the asymmetry @xcite , and since that time various models have been proposed to explain it .
but we still do nt have any idea which , if any , is correct , because baryogenesis usually depends on unknown physics beyond the reach of current experiments and on the unknown early history of the universe beyond the reach of current observations ..
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a successful cosmological history must produce necessary relics such as the baryon asymmetry , but must also avoid or dilute unwanted cosmological relics such as gravitinos @xcite and moduli @xcite , which can destroy the successful predictions of big bang nucleosynthesis @xcite or over - dominate the universe depending on the scale of supersymmetry breaking .
thermal inflation @xcite provides a compelling solution to the unwanted relic problem .
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Suppose that you have an abstract for a scientific paper: we present a new mass estimate for the hercules dwarf spheroidal galaxy ( dsph ) , based on the revised velocity dispersion obtained by @xcite .
the removal of a significant foreground contamination using newly acquired strmgren photometry has resulted in a reduced velocity dispersion . using this new velocity dispersion of @xmath0
, we find a mass of @xmath1 within the central 300pc , which is also the half - light radius , and a mass of @xmath2m@xmath3 within the reach of our data to 433pc , significantly lower than previous estimates .
we derive an overall mass - to - light ratio of @xmath4 $ ] .
our mass estimate calls into question recent claims of a common mass scale for dsph galaxies .
additionally , we find tentative evidence for a velocity gradient in our kinematic data of @xmath5kms@xmath6kpc@xmath6 , and evidence of an asymmetric extension in the light distribution at @xmath7kpc .
we explore the possibility that these features are due to tidal interactions with the milky way .
we show that there is a self - consistent model in which hercules has an assumed tidal radius of @xmath8pc , an orbital pericentre of @xmath9kpc , and a mass within @xmath10 of @xmath11m@xmath3 .
proper motions are required to test this model .
although we can not exclude models in which hercules contains no dark matter , we argue that hercules is more likely to be a dark matter dominated system which is currently experiencing some tidal disturbance of its outer parts . .
And you have already written the first three sentences of the full article: dwarf spheroidal ( dsph ) galaxies are believed to play an important role in the formation and evolution of much more luminous galaxies ( e.g. * ? ? ?
dsphs are characterized by their low surface brightness , low total luminosity and spheroidal shapes which are consistent with their pressure - supported stellar kinematics ( e.g. * ? ? ?
knowledge of dsph masses is essential for comparison with cosmological simulations of galaxy formation ..
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good mass estimates help us to establish whether the paucity in the number of observed systems ( a few tens ) to the number of predicted satellite haloes ( several thousands ) represents a fundamental failure of our cosmological model ( e.g. * ? ? ?
* ) , or whether it is simply telling us that galaxy formation is inefficient on small scales ( e.g. * ? ? ?
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Suppose that you have an abstract for a scientific paper: we address some current theoretical issues around ultra - high energy cosmic rays .
we recall that scenarios producing more @xmath0rays than cosmic rays up to high redshift can in general only provide a sub - dominant contribution to the ultra - high energy cosmic ray flux .
this includes extra - galactic top - down and the z - burst scenarios .
finally we discuss the influence of large scale cosmic magnetic fields on ultra - high energy cosmic ray propagation which is currently hard to quantify .
the views presented here represent the authors perspective . .
And you have already written the first three sentences of the full article: high energy cosmic ray ( cr ) particles are shielded by earth s atmosphere and reveal their existence on the ground only by indirect effects such as ionization and showers of secondary charged particles covering areas up to many km@xmath1 for the highest energy particles .
in fact , in 1912 victor hess discovered crs by measuring ionization from a balloon @xcite , and in 1938 pierre auger proved the existence of extensive air showers ( eas ) caused by primary particles with energies above @xmath2ev by simultaneously observing the arrival of secondary particles in geiger counters many meters apart @xcite .
after almost 90 years of research , the origin of cosmic rays is still an open question , with a degree of uncertainty increasing with energy @xcite : only below 100 mev kinetic energy , where the solar wind shields protons coming from outside the solar system , the sun must give rise to the observed proton flux ..
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above that energy the cr spectrum exhibits little structure and is approximated by broken power laws @xmath3 : at the energy @xmath4ev called the `` knee '' , the flux of particles per area , time , solid angle , and energy steepens from a power law index @xmath5 to one of index @xmath6 .
the bulk of the crs up to at least that energy is believed to originate within the milky way galaxy , typically by shock acceleration in supernova remnants .
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Suppose that you have an abstract for a scientific paper: phase - sensitive tests of pairing symmetry have provided strong evidence for predominantly @xmath0-wave pairing symmetry in both the hole- and electron - doped high - t@xmath1 cuprate superconductors .
temperature dependent measurements in yba@xmath2cu@xmath3o@xmath4 ( ybco ) indicate that the @xmath0-wave pairing dominates , with little if any imaginary component , at all temperatures from 0.5k through t@xmath1 . in this article
we review some of this evidence and discuss the implications of the universal @xmath0-wave pairing symmetry in the cuprates . .
And you have already written the first three sentences of the full article: pairing symmetry in the cuprate superconductors was a subject of intense debate for many years after the discovery of high - temperature superconductivity @xcite , primarily because the interpretation of many conventional techniques , such as quasiparticle tunneling , nmr , angle - resolved photoemission , and penetration depth measurements , was model - dependent .
nevertheless , these phase - insensitive techniques have produced a large body of evidence for @xmath0-wave pairing in the cuprates .
the recent development of phase - sensitive pairing symmetry test @xcite , has yielded compelling evidence for predominantly @xmath0-wave pairing symmetry in a number of optimally doped cuprates @xcite ..
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a question naturally arises : how universal is the @xmath5 pairing in cuprate superconductors ?
there are numerous theoretical studies suggesting the stability of the @xmath0-wave pair state depends on the details of band structure and the pairing potential @xcite .
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Suppose that you have an abstract for a scientific paper: we present a new analysis of the motion of pressure - confined , broad line region ( blr ) clouds in active galactic nuclei ( agns ) taking into account the combined influence of gravity and radiation pressure .
we calculate cloud orbits under a large range of conditions and include the effect of column density variation as a function of location .
the dependence of radiation pressure force on the level of ionization and the column density are accurately computed .
the main results are : a. the mean cloud locations ( ) and line widths ( fwhms ) are combined in such a way that the simple virial mass estimate , @xmath0 , gives a reasonable approximation to @xmath1 even when radiation pressure force is important .
the reason is that @xmath2 rather than @xmath3 is the main parameter affecting the planar cloud motion .
b. reproducing the mean observed , fwhm and line intensity of and requires at least two different populations of clouds . c. the cloud location is a function of both @xmath4 and @xmath2 . given this
, we suggest a new approximation for which , when inserted into the bh mass equation , results in a new approximation for @xmath1 .
the new expression involves @xmath4 , fwhm and two constants that are obtained from a comparison with available @xmath5 mass estimates .
it deviates only slightly from the old mass estimate at all luminosities .
d. the quality of the present black hole mass estimators depends , critically , on the way the present @xmath5 agn sample ( 29 objects ) represents the overall population , in particular the distribution of . .
And you have already written the first three sentences of the full article: the profiles of the broad emission lines in the spectrum of active galactic nuclei ( agns ) are the main source of information about the motion of the high density gas in the broad line region ( blr ) .
detailed studies of such profiles have been the focus of intense investigation for many years ( see netzer 1990 for a review of older work and marziani et al .
1996 and richards et al ..
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2002 for more recent publications ) .
unfortunately , several rather different geometries can conspire to result in similar line profiles and today , there is no way to infer , directly , the global blr motion from line profile fitting .
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Suppose that you have an abstract for a scientific paper: in this paper , it is proved that every @xmath0-sparse vector @xmath1 can be exactly recovered from the measurement vector @xmath2 via some @xmath3-minimization with @xmath4 , as soon as each @xmath0-sparse vector @xmath1 is uniquely determined by the measurement @xmath5 . .
And you have already written the first three sentences of the full article: define the norm @xmath6 , of a vector @xmath7 by the number of its nonzero components when @xmath8 , the quantity @xmath9 when @xmath10 , and the maximum absolute value @xmath11 of its components when @xmath12 .
we say that a vector @xmath1 is _
@xmath0-sparse _ if @xmath13 , i.e. , the number of its nonzero components is less than or equal to @xmath0 . in this paper.
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, we consider the problem of compressive sensing in finding @xmath0-sparse solutions @xmath1 to the linear system @xmath14 via solving the @xmath3-minimization problem : @xmath15 where @xmath16 , @xmath17 , @xmath18 is an @xmath19 matrix , and @xmath20 is the observation data ( @xcite ) .
one of the basic questions about finding @xmath0-sparse solutions to the linear system is under what circumstances the linear system has a unique solution in @xmath21 , the set of all @xmath0-sparse vectors .
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Suppose that you have an abstract for a scientific paper: we present recent results of hadron spectroscopy and hadron - hadron interaction from the perspective of constituent quark models .
we pay special attention to the role played by higher order fock space components in the hadron spectra and the connection of this extension with the hadron - hadron interaction .
the main goal of our description is to obtain a coherent understanding of the low - energy hadron phenomenology without enforcing any particular model , to constrain its characteristics and learn about low - energy realization of the theory .
heavy hadrons , constituent quark model , many - quark systems .
And you have already written the first three sentences of the full article: for almost thirty years after the discovery of the @xmath0 and its excitations , the so - called november revolution @xcite , heavy hadron spectroscopy was at rest .
paraphrasing lord kelvin famous speech @xcite , by 2003 there were only two clouds on the horizon obscuring _ the beauty and clearness of the dynamical theory_. in the hadron spectra these _ two clouds _ were on the one hand the missing resonance problem , i.e. , all quark models predict a proliferation of excited states which have not been measured , and , on the other hand , the observation by babar of an open - charm meson , the @xmath1 , whose properties were quite different from those predicted by quark potential models . since those peaceful days
an increase on both amount and quality of experimental data has shown quite a different picture , far more involved and convoluted , with the observation of the well - known @xmath2 , the @xmath3 , @xmath4 , @xmath5 , @xmath6 , and several other states ..
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based on gell - mann conjecture @xcite the hadronic experimental data were classified either as @xmath7 or @xmath8 states according to @xmath9 irreducible representations , nowadays this hypothesis may be in question . therefore , the study of the role played by higher order fock space components in the hadron spectra , allowed by the gell - mann classification , is an interesting issue to address . in this talk
we give an overview of a project for getting a coherent understanding of the low - energy hadron phenomenology from the perspective of constituent quark models @xcite .
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Suppose that you have an abstract for a scientific paper: a microscopic approach has been employed to study the kaon productions in heavy ion collisions .
the momentum integrated boltzmann equation has been used to study the evolution of strangeness in the system formed in heavy ion collision at relativistic energies .
the kaon productions have been calculated for different centre of mass energies ( @xmath0 ) ranging from ags to rhic .
the results have been compared with available experimental data .
we obtain a non - monotonic horn like structure for @xmath1 when plotted with @xmath0 with the assumption of an initial partonic phase beyond a certain threshold in @xmath2 .
however , a monotonic rise of @xmath1 is observed when a hadronic initial state is assumed for all @xmath0 .
experimental values of @xmath3 are also reproduced within the ambit of the same formalism .
results from scenarios where the strange quarks and hadrons are formed in equilibrium and evolves with and without secondary productions have also been presented . . .
And you have already written the first three sentences of the full article: the lattice simulation of quantum chromodynamic equation of state ( eos ) predicts that the properties of nuclear matter at extreme densities and/or temperatures are governed by the partonic degrees of freedom @xcite .
a series of experiments have been performed @xcite and planned @xcite to produce such a partonic state of matter , called quark gluon plasma ( qgp ) by colliding nuclei at ultra - relativistic energies .
rigorous experimental and theoretical efforts are on to create and detect such a novel state of matter @xcite ..
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various signals have been proposed for the detection of qgp - the pros and cons of these signals are matter of intense debate .
the study of the ratio , @xmath4 is one such currently debated issue .
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Suppose that you have an abstract for a scientific paper: let @xmath0 be the minimum length of a knot on the cubic lattice ( namely the minimum length necessary to construct the knot in the cubic lattice ) .
this paper provides upper bounds for @xmath0 of a nontrivial knot @xmath1 in terms of its crossing number @xmath2 as follows : @xmath3 the ropelength of a knot is the quotient of its length by its thickness , the radius of the largest embedded normal tube around the knot .
we also provide upper bounds for the minimum ropelength @xmath4 which is close to twice @xmath0 : @xmath51.5 c(k)^2 + 9.15 c(k ) + [email protected] c(k)^2 + 14.58 c(k ) + 16.90@xmath7 .
And you have already written the first three sentences of the full article: a knot can be embedded in many different ways in @xmath8-space , smooth or piecewise linear .
polygonal knots are those which consist of finite line segments , called _ sticks _ , attached end - to - end .
a _ lattice knot _ is a polygonal knot in the cubic lattice @xmath9 . for further studies on lattice knots the readers.
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are referred to @xcite .
a quantity that we may naturally be interested on lattice knots is the minimum length necessary to realize a knot as a lattice knot .
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Suppose that you have an abstract for a scientific paper: the solar @xmath0-process abundances have been analyzed in the framework of a galactic chemical evolution ( gce ) model .
the aim of this work is to implement the study by @xcite , who investigated the effect of one of the major uncertainties of asymptotic giant branch ( agb ) yields , the internal structure of the @xmath1c pocket .
we present gce predictions of @xmath0-process elements computed with additional tests in the light of the suggestions provided in recent publications .
+ the analysis is extended to different metallicities , by comparing gce results and updated spectroscopic observations of unevolved field stars .
we verify that the gce predictions obtained with different tests may represent , on average , the evolution of selected neutron - capture elements in the galaxy .
the impact of an additional weak @xmath0-process contribution from fast - rotating massive stars is also explored . .
And you have already written the first three sentences of the full article: agb stars with low initial mass are the major responsible for the nucleosynthesis of solar @xmath0 isotopes with @xmath2 @xmath3 90 @xcite .
+ the main neutron source of low - mass agb models is the @xmath1c(@xmath4 , n)@xmath5o reaction , which burns radiatively during the interpulse in a thin layer of the he intershell , the so - called _
@xmath7 @xcite ..
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the formation of the @xmath1c pocket requires an unknown mixing mechanism that allows partial mixing of a few protons from the convective envelope into the top layers of the radiative he- and c - rich intershell .
this is assumed to occur at the quenching of a third dredge up ( tdu ) episode .
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Suppose that you have an abstract for a scientific paper: we introduce a numerical method for identifying topological order in two - dimensional models based on one - dimensional bulk operators . the idea is to identify approximate symmetries supported on thin strips through the bulk that behave as string operators associated to an anyon model .
we can express these ribbon operators in matrix product form and define a cost function that allows us to efficiently optimize over this ansatz class .
we test this method on spin models with abelian topological order by finding ribbon operators for @xmath0 quantum double models with local fields and ising - like terms . in addition , we identify ribbons in the abelian phase of kitaev s honeycomb model which serve as the logical operators of the encoded qubit for the quantum error - correcting code .
we further identify the topologically encoded qubit in the quantum compass model , and show that despite this qubit , the model does not support topological order .
finally , we discuss how the method supports generalizations for detecting nonabelian topological order . despite the apparent simplicity of quantum spin models
, they can exhibit a wide variety of interesting and potentially useful phenomena .
these range from conventional magnetic order to the more novel topological@xcite and symmetry - protected@xcite and symmetry - enriched@xcite topological orders which are of interest in both condensed matter physics@xcite and quantum information theory.@xcite these states are disordered in the sense of landau - ginzburg - wilson , however they do exhibit properties distinct from the usual disordered phases .
for example , topological phases possess quasiparticle excitations , known as anyons , whose braid relations can be far more exotic than those of fermions or bosons.@xcite these phases also have ground state degeneracy which depends on the topology of the lattice.@xcite this protected degeneracy has prompted the investigation of topologically ordered models as quantum memories.@xcite quantum information....
And you have already written the first three sentences of the full article: -type and @xmath17-type four - body interactions on alternate plaquettes of a square lattice , and the ( exact ) ribbon operators are the string - like products of @xmath18 and @xmath17 shown above .
these ribbon operators commute with the hamiltonian terms but anticommute with each other , thus identifying a phase with @xmath19 topological order.,title="fig : " ] in this section , we review the physical properties of anyon models that characterize a topological phase . of course
, not all topological phases have an associated anyon model , for example the cubic code,@xcite however we will tailor our method to those phases with anyonic excitations ..
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this discussion of anyon models will motivate our definition in the subsequent section of a _ ribbon operator _ for a spin model defined by some local hamiltonian @xmath20 on a lattice in two dimensions .
we will argue that this definition captures the essential features outlined below of a topologically ordered model by thinking about anyons as quasiparticle excitations of the spin model .
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Suppose that you have an abstract for a scientific paper: using a quantum electrodynamic framework , we calculate the off - resonant scattering of a broad - band x - ray pulse from a sample initially prepared in an arbitrary superposition of electronic states .
the signal consists of single - particle ( incoherent ) and two - particle ( coherent ) contributions that carry different particle form factors that involve different material transitions .
single - molecule experiments involving incoherent scattering are more influenced by inelastic processes compared to bulk measurements .
the conditions under which the technique directly measures charge densities ( and can be considered as diffraction ) as opposed to correlation functions of the charge - density are specified .
the results are illustrated with time- and wavevector - resolved signals from a single amino acid molecule ( cysteine ) following an impulsive excitation by a stimulated x - ray raman process resonant with the sulfur k - edge .
our theory and simulations can guide future experimental studies on the structures of nano - particles and proteins . .
And you have already written the first three sentences of the full article: x - ray techniques have long been applied to image the electronic charge density of atoms , molecules , and materials @xcite .
recently - developed x - ray free electron laser sources , which generate short ( attosecond ) , intense pulses , open up numerous potential applications for high temporal and spatial resolution studies @xcite .
one exciting application is the determination of molecular structure by x - ray diffraction of nanocrystals @xcite avoiding the crystal growth process which is often the bottleneck in structure determination @xcite ; it may take decades to crystallize a complex protein ..
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it is much easier to grow nanocrystals than the many - microns - sized samples required by conventional crystallography .
this has been demonstrated experimentally in nanocrystals for the water splitting photosynthetic complex ii @xcite , a mimivirus @xcite , and a membrane protein @xcite .
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Suppose that you have an abstract for a scientific paper: the rapidly growing wave of wireless data service is pushing against the boundary of our communication network s processing power .
the pervasive and exponentially increasing data traffic present imminent challenges to all the aspects of the wireless system design , such as spectrum efficiency , computing capabilities and fronthaul / backhaul link capacity . in this article , we discuss the challenges and opportunities in the design of scalable wireless systems to embrace such a bigdata " era . on one hand , we review the state - of - the - art networking architectures and signal processing techniques adaptable for managing the bigdata traffic in wireless networks . on the other hand , instead of viewing mobile bigdata as a unwanted burden ,
we introduce methods to capitalize from the vast data traffic , for building a bigdata - aware wireless network with better wireless service quality and new mobile applications .
we highlight several promising future research directions for wireless communications in the mobile bigdata era . .
And you have already written the first three sentences of the full article: decades of exponential growth in commercial data services has ushered in the so - called bigdata " era , to which the expansive mobile wireless network is a critical data contributor . as of @xmath0 , the global penetration of mobile subscribers has reached @xmath1 , producing staggeringly @xmath2 exabytes ( @xmath3 ) of mobile data worldwide .
the surge of mobile data traffic in recent years is mainly attributed to the popularity of smartphones , phone cameras , mobile tablets and other smart mobile devices that support mobile broadband applications , e.g. , online music , video and gaming as shown in fig . [ 71 ] . with a compound annual growth rate of over @xmath4
, it is expected that the mobile data traffic will increase by @xmath5 times from @xmath6 to @xmath7 ..
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in addition to the vast amount of wireless source data , modern wireless signal processing often amplifies the system s pressure from bigdata in pursuit of higher performance gain .
for instance , mimo antenna technologies are now extensively used to boost throughput and reliability at both mobile terminals ( mts ) and base stations ( bss ) of high speed wireless services .
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Suppose that you have an abstract for a scientific paper: we examine the prospects for discovering and elucidating the weakly - coupled higgs sector at future collider experiments .
the higgs search consists of three phases : ( i ) discovery of a higgs candidate , ( ii ) verification of the higgs interpretation of the signal , and ( iii ) precision measurements of higgs sector properties .
the discovery of one higgs boson with standard model properties is not sufficient to expose the underlying structure of the electroweak symmetry breaking dynamics .
it is critical to search for evidence for a non - minimal higgs sector and/or new physics associated with electroweak symmetry breaking dynamics .
an improvement in precision electroweak data at future colliders can play a useful role in confirming the theoretical interpretation of the higgs search results . .
And you have already written the first three sentences of the full article: present day colliders test the standard model at an energy scale of order 100 gev .
precision experiments at lep , slc and tevatron ( with some additional measurements at lower energies ) have measured more than twenty separate experimental observables , and have confirmed the standard model predictions with an accuracy of one part in a thousand @xcite .
a few anomalies in the data could suggest hints of new physics beyond the standard model @xcite , although no deviations have been rigorously confirmed . nevertheless , the verification of the standard model is not yet complete ..
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absent to date is any experimental signal that sheds light on the dynamics responsible for electroweak symmetry breaking .
any consistent theory of electroweak symmetry breaking must generate goldstone bosons which are absorbed by the @xmath0 and @xmath1 gauge bosons , thereby generating the gauge boson masses .
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Suppose that you have an abstract for a scientific paper: we present a systematic study of the energy of vanishing flow by considering symmetric colliding nuclei ( between @xmath0c and @xmath1u ) at normalized impact parameters using variety of equations of state ( with and without momentum dependent interactions ) as well as different nucleon - nucleon cross sections .
a perfect power law mass dependence is obtained in all the cases which passes through calculated points nicely .
further , the choice of impact parameter affects the energy of vanishing flow drastically , demanding a very accurate measurement of the impact parameter .
however , the energy of vanishing flow is less sensitive towards the equation of state as well as its momentum dependence .
pacs number : 25.70.-z , 25.70.jj + electronic address : [email protected] .
And you have already written the first three sentences of the full article: the heavy - ion collisions around fermi energies have been a subject of intensive theoretical and experimental investigations in recent times @xcite .
this is primarily due to the onset of multifragmentation @xcite , collective flow and its disappearance @xcite as well as a mixture of fusion , decay , and fission @xcite dominating the physics at these incident energies . among all these phenomena ,
collective flow has been found to be sensitive towards the nuclear matter equation of state ( eos ) as well as towards nucleon - nucleon ( nn ) cross section @xcite . at low incident energies , dominance of attractive mean field.
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prompts the emission of particles into backward hemi - sphere whereas particle emission at higher incident energies is dominated by the forward scattering . in other words ,
the net transverse flow disappears at a certain incident energy termed as the energy of vanishing flow ( evf ) @xcite .
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Suppose that you have an abstract for a scientific paper: we revisit the model of a system made up of a brownian quantum oscillator under the influence of an external classical force and linearly coupled to an environment made up of many quantum oscillators at zero or finite temperature .
we show that the hpz master equation for the reduced density matrix derived earlier [ b.l .
hu , j.p .
paz , y. zhang , phys .
rev .
d * 45 * , 2843 ( 1992 ) ] with coefficients obtained from solutions of integro - differential equations can assume closed functional forms for a fairly general class of spectral densities of the environment at arbitrary temperature and coupling strength .
as an illustration of these new results we solve the corresponding master equation and calculate , among other physical quantities , the uncertainty function whose late time behavior can be obtained fully .
this produces a formula for investigating the standard quantum limit which is central to addressing many theoretical issues in macroscopic quantum phenomena and experimental concerns related to low temperature precision measurements .
we find that any initial state always settles down to a gaussian density matrix whose covariance is determined by the thermal reservoir and whose mean is determined by the external force . for more general spectra
we show that the solution of the master equation can be reduced to solving for the motion of a classical parametric oscillator with parametric frequency determined by the _
unsolved for _ master equation coefficients .
states in these systems experience evolution that is parametrically similar to the simpler evolution explicitly determined for in the case of laurent - series spectra . .
And you have already written the first three sentences of the full article: in this paper we continue the lineage of work on quantum brownian motion via the influence functional path - integral method of feynman and vernon@xcite used by caldeira and leggett@xcite to derive a master equation for a high - temperature ohmic environment , which corresponds to the markovian regime . following this , caldeira , cerdeira and ramaswamy ( ccr)@xcite derived the markovian master equation for the system with weak coupling to an ohmic bath , that was claimed to be valid at arbitrary temperature ( sec .
[ sec - caldeira ] ) . at the same time unruh and
zurek@xcite derived a more complete and general master equation that incorporated a colored noise at finite temperature ..
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finally hu , paz and zhang ( hpz ) @xcite derived an exact master equation for a general environment ( arbitrary temperature and spectral density ) which preserves the positive definiteness of the reduced density matrix , an important property missed out in many earlier derivations . for many calculations ,
physicists often invoke markovian master equations as they are easier to solve owing to their having compact , functional representations .
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Suppose that you have an abstract for a scientific paper: we consider a two - component one - dimensional model of gap solitons ( gss ) , which is based on two nonlinear schrdinger equations , coupled by repulsive xpm ( cross - phase - modulation ) terms , in the absence of the spm ( self - phase - modulation ) nonlinearity .
the equations include a periodic potential acting on both components , thus giving rise to gss of the symbiotic " type , which exist solely due to the repulsive interaction between the two components .
the model may be implemented for holographic solitons " in optics , and in binary bosonic or fermionic gases trapped in the optical lattice .
fundamental symbiotic gss are constructed , and their stability is investigated , in the first two finite bandgaps of the underlying spectrum .
symmetric solitons are destabilized , including their entire family in the second bandgap , by symmetry - breaking perturbations above a critical value of the total power .
asymmetric solitons of intra - gap and inter - gap types are studied too , with the propagation constants of the two components falling into the same or different bandgaps , respectively .
the increase of the asymmetry between the components leads to shrinkage of the stability areas of the gss .
inter - gap gss are stable only in a strongly asymmetric form , in which the first - bandgap component is a dominating one .
intra - gap solitons are unstable in the second bandgap .
unstable two - component gss are transformed into persistent breathers .
in addition to systematic numerical considerations , analytical results are obtained by means of an extended ( tailed " ) thomas - fermi approximation ( tfa ) .
99 b. a. malomed , d. mihalache , f. wise , and l. torner , spatiotemporal optical solitons , " j. opt .
b : quant . semicl . opt .
* 7 * , r53r72 ( 2005 ) .
f. lederer , g. i. stegeman , d. n. christodoulides , g. assanto , m. segev , and y. silberberg , discrete solitons in optics , " phys .
rep . * 463 * , 1 ( 2008 ) .
y. v. kartashov , v. a.....
And you have already written the first three sentences of the full article: studies of solitons in spatially periodic ( lattice ) potentials have grown into a vast area of research , with profoundly important applications to nonlinear optics , plasmonics , and matter waves in quantum gases , as outlined in recent reviews @xcite . in ultracold bosonic and fermionic gases ,
periodic potentials can be created , in the form of optical lattices , by coherent laser beams illuminating the gas in opposite directions @xcite .
effective lattice potentials for optical waves are induced by photonic crystals , which are built as permanent structures by means of various techniques @xcite , or as laser - induced virtual structures in photorefractive crystals @xcite ..
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parallel to the progress in the experiments , the study of the interplay between the nonlinearity and periodic potentials has been an incentive for the rapid developments of theoretical methods @xcite .
both the experimental and theoretical results reveal that solitons can be created in lattice potentials , if they do not exist in the uniform space [ this is the case of gap solitons ( gss ) supported by the self - defocusing nonlinearity , see original works @xcite and reviews @xcite ] , and solitons may be stabilized , if they are unstable without the lattice ( multidimensional solitons in the case of self - focusing , as shown in refs .
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Suppose that you have an abstract for a scientific paper: we provide a brief review and detailed analysis of the spin - orbit density wave ( sodw ) , proposed as a possible explanation to the ` hidden order ' phase of uru@xmath0si@xmath0 . due to the interplay between inter - orbital coulomb interaction and spin - orbit coupling ( soc ) in this compound ,
the sodw is shown to arise from fermi surface nesting instability between two spin - orbit split bands .
an effective low - energy hamiltonian including single - particle soc and two - particle sodw is derived , while numerical results are calculated by using density - functional theory ( dft ) based band structure input .
computed gapped quasiparticle spectrum , entropy loss and spin - excitation spectrum are in detailed agreement with experiments .
interestingly , despite the fact that sodw governs dynamical spin - excitations , the static magnetic moment is calculated to be _
zero _ , owing to the time - reversal invariance imposed by soc . as a consequence
, sodw can be destroyed by finite magnetic field even at zero temperature .
our estimation of the location of the quantum critical point is close to the experimental value of @xmath1 35 t. finally , we extend the idea of sodw to other soc systems including iridium oxides ( iridates ) and two - dimensional electronic systems such as biag@xmath0 surface and laalo@xmath2/srtio@xmath2 interface . we show hints of quasiparticle gapping , reduction of preexisting magnetic moment , large magneto - resistance etc . in these systems which can be explained consistently within the sodw theory .
spin - orbit density wave ; hidden order ; heavy fermion ; quantum phase transition , uru@xmath0si@xmath0 . .
And you have already written the first three sentences of the full article: a second order phase transition has been observed in the heavy fermion metal uru@xmath0si@xmath0 at @xmath3=17.5 k via a sharp discontinuous jump in the specific heat with about 24% entropy loss.@xcite considering an associated sharp anomaly in the @xmath4axis magnetic susceptibility , it was initially assumed to be an antiferromagnetic ( af ) phase.@xcite however , in subsequent works,@xcite including a very recent one,@xcite the presence of any static magnetic moment has been eliminated .
this apparent ` magnetic dichotomy ' has remained a smoking gun feature of the phase , known as the ` so - called ' hidden order ( ho ) phase of uru@xmath0si@xmath0 .
additional key fingerprints of the ho state include a relatively weak intensity peak at the commensurate wavevector @xmath5=(001),@xcite and a dispersive collective excitation at an incommensurate vector @xmath6=([email protected],0,0),@xcite as probed by inelastic neutron scattering ( ins ) measurement ..
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furthermore , the ins spectral weight loss at the incommensurate wavevector , as opposed to the commensurate one , can fully account for the entropy loss at the ho transition .
direct spectroscopies including angle - resolved photoemission spectroscopy ( arpes)@xcite scanning tunneling microscopy ( stm)@xcite and point contact spectroscopy@xcite have found the presence of a fermi surface ( fs ) gapping at the ho state , which is consistent with the bulk measurement of about 40% loss of quasiparticle weight at this phase.@xcite finally , a shubunikov de - hass ( sdh ) measurement finds that the quantum oscillation frequency does not change by any significant amount in going from ho phase at ambient pressure to the large moment af ( lmaf ) phase at high pressure.@xcite considering also the high - magnetic field phase diagram of uru@xmath0si@xmath0 where the ho phase is intertwined with the lmaf and possibly with other unknown phases,@xcite this sdh data can be interpreted along the same line . therefore , a feasible solution to the ho problem lies in a theory which can explain the ` magnetic dichotomy ' , while accounting for the large fs gapping and entropy change , among others .
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Suppose that you have an abstract for a scientific paper: propositional linear time temporal logic ( ltl ) is the standard temporal logic for computing applications and many reasoning techniques and tools have been developed for it .
tableaux for deciding satisfiability have existed since the 1980s . however , the tableaux for this logic do not look like traditional tree - shaped tableau systems and their processing is often quite complicated .
we present a new simple traditional - style tree - shaped tableau for ltl and prove that it is sound and complete . as well as being simple to understand , to introduce to students and to use manually , it also seems simple to implement and promises to be competitive in its automation .
it is particularly suitable for parallel implementations .
note : the latest version of this report can be found via http://www.csse.uwa.edu.au/~mark/research/online/ltlsattab.html . .
And you have already written the first three sentences of the full article: propositional linear time temporal logic , ltl , is important for hardware and software verification@xcite .
ltl satisfiability checking ( ltlsat ) is receiving renewed interest with advances computing power , several industry ready tools , some new theoretical techniques , studies of the relative merits of different approaches , implementation competitions , and benchmarking : @xcite .
common techniques include automata - based approaches @xcite and resolution @xcite as well as tableaux @xcite ..
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each type of approach has its own advantages and disadvantages and each can be competitive at the industrial scale ( albeit within the limits of what may be achieved with pspace complexity ) .
the state of the art in tableau reasoners for ltl satisfiability testing is the technique from @xcite which is used in portfolio reasoners such as @xcite .
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Suppose that you have an abstract for a scientific paper: we study the evolution of an exciton confined in a quantum dot adiabatically controlled by a frequency - swept ( chirped ) laser pulse in the presence of carrier - phonon coupling .
we focus on the dynamics induced by a linearly polarized beam and analyze the decoherence due to phonon - assisted biexciton generation .
we show that if the biexciton state is shifted down by a few mev , as is typically the case , the resulting decoherence is strong even at low temperatures . as a result ,
efficient state preparation is restricted to a small parameter area corresponding to low temperatures , positive chirps and moderate pulse areas . .
And you have already written the first three sentences of the full article: the recently demonstrated @xcite high - fidelity preparation of a single exciton state in a self - assembled quantum dot ( qd ) by means of adiabatic evolution induced by a chirped laser pulse ( referred to as _ adiabatic rapid passage _ , arp ) opens new possibilities of charge control in qds .
in contrast to the more traditional rabi flops @xcite as well as to methods based on voltage control @xcite , arp is much less sensitive to the details of the driving field . in particular , in the ideal case , the arp technique ensures the full inversion of occupation between the empty dot and exciton states as soon as the pulse intensity reaches the threshold for the adiabatic passage .
however , as qds are embedded in a semiconductor crystal matrix , carrier - phonon interactions are usually found to considerably limit the fidelity of various optical control schemes ..
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the phonon - induced dephasing process is inevitable in such systems and leads to loss of information .
these mechanisms have been investigated theoretically @xcite and have been confirmed experimentally @xcite . as we have recently shown @xcite , in the case of the arp
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Suppose that you have an abstract for a scientific paper: controlling the motion of nano and microscale objects in a fluid environment is a key factor in designing optimized tiny machines that perform mechanical tasks such as transport of drugs or genetic material in cells , fluid mixing to accelerate chemical reactions , and cargo transport in microfluidic chips .
directed motion is made possible by the coupled translational and rotational motion of asymmetric particles . a current challenge in achieving directed and controlled motion at the nanoscale lies in overcoming random brownian motion due to thermal fluctuations in the fluid .
we use a hybrid lattice - boltzmann molecular dynamics method with full hydrodynamic interactions and thermal fluctuations to demonstrate that controlled propulsion of individual nanohelices in an aqueous environment is possible .
we optimize the propulsion velocity and the efficiency of externally driven nanohelices .
we quantify the importance of the thermal effects on the directed motion by calculating the pclet number for various shapes , number of turns and pitch lengths of the helices .
consistent with the experimental microscale separation of chiral objects , our results indicate that in the presence of thermal fluctuations at pclet numbers @xmath0 , chiral particles follow the direction of propagation according to its handedness and the direction of the applied torque making separation of chiral particles possible at the nanoscale .
our results provide criteria for the design and control of helical machines at the nanoscale .
most natural organisms and molecules exhibit chiral structures that significantly influence their chemical and physical behavior .
for example , most proteins are left - handed while sugars are right - handed .
drug molecules which target proteins , therefore , have different effects depending on their chirality .
thalidomide is perhaps the most infamous example of a drug whose devastating health effects have been ascribed to the presence of both left and right handed enantiomers....
And you have already written the first three sentences of the full article: the fundamental quantity to be considered in the driven motion of helical particles is the propulsion velocity @xmath14 induced by the rotational motion from the application of a constant external torque .
the angular velocity of the helix for a constant torque depends on viscous drag coefficients which are presented in fig .
we first present results for optimizing the geometric shape parameters for the helical particles shown in fig ..
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[ directions ] such that @xmath14 is maximized by using method 1 as described in the methods section . during optimization
the hydrodynamic interactions are fully taken into account , but thermal noise is neglected .
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Suppose that you have an abstract for a scientific paper: i present an overview of predictions for the heavy ion program at the large hadron collider .
it is mainly based on the material presented during the workshop heavy ion collisions at the lhc - last call for predictions , held in the frame of the cern theory institute from may 14th to june 10th 2007 .
predictions on both bulk properties and hard probes are reviewed . .
And you have already written the first three sentences of the full article: in this paper i present an overview of the predictions for pb - pb collisions at @xmath0 tev at the large hadron collider , mainly based on the material presented during the workshop heavy ion collisions at the lhc - last call for predictions , held in the frame of the cern theory institute from may 14th to june 10th 2007 @xcite . such compilation ( see also @xcite , and @xcite for the analogous one for rhic ) should be useful for : ( a ) distinguishing pre- from post - dictions ; ( b ) assuming that a model tested at rhic ( and eventually sps ) energies can be extrapolated to the lhc , the huge lever arm in energy provides very strong constraints ; and ( c ) providing a frozen image of our present understanding of ultra - relativistic heavy ion collisions .
i have classified the predictions in : bulk properties ( section 2 ) : multiplicities ( see pre - rhic predictions in @xcite ) , azimuthal asymmetries , hadronic flavor observables and correlations at low transverse momentum ; and hard and electromagnetic probes ( section 3 ) : high transverse momentum observables and jets , quarkonium and heavy quarks , and leptonic probes and photons , extensively documented in @xcite .
unless otherwise stated , the predictions presented here can be found in @xcite and will be referenced by the name of their first author ..
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finally i draw some conclusions .
multiplicity is a first - day observable .
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Suppose that you have an abstract for a scientific paper: we revisit the swift - hohenberg model for two - dimensional hexagonal patterns in the bistability region where hexagons coexist with the uniform quiescent state .
we both analyze the law of motion of planar interfaces ( separating hexagons and uniform regions ) , and the stability of localized structures .
interfaces exhibit properties analogous to that of interfaces in crystals , such as faceting , grooving and activated growth or melting " . in the nonlinear regime , some spatially disordered heterogeneous configurations do not evolve in time .
frozen states are essentially composed of extended polygonal domains of hexagons with pinned interfaces , that may coexist with isolated localized structures randomly distributed in the quiescent background .
localized structures become metastable at the pinning / depinning transition of interfaces . in some region of the parameter space ,
localized structures shrink meanwhile interfaces are still pinned .
the region where localized structures have an infinite life - time is relatively limited . .
And you have already written the first three sentences of the full article: spatial disorder is a generic feature of pattern formation . whereas the simplest patterns that appear in numbers of physical or chemical systems driven out of thermodynamic equilibrium are periodic structures ( such as stripes , squares or hexagons ) , in practice , many steady patterns observed in spatially extended systems are more complex and disordered at large scale @xcite .
why disordered configurations spontaneously form ( without the help of impurities or any quenched disorder ) and do not asymptotically evolve with time toward more ordered states is still not fully understood .
for instance , systems where various ( say , two ) patterns of different symmetries coexist can easily lead to disordered states . a basic example is rayleigh - bnard convection of non - boussinesq fluids , where hexagonal patterns bifurcate subcritically and are stable along with the uniform conductive state within a whole interval of rayleigh numbers . in bistability regions , asymptotic configurations may be either homogeneous ( containing a single phase ) or heterogeneous , with both phases present and distributed in a non - regular way ..
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heterogeneous states have been identified experimentally in rayleigh - bnard convection @xcite , vibrated granular materials @xcite , or turing patterns and related gas - discharge systems @xcite .
spatial disorder has been also proposed as a generic feature of pattern formation in ecosystems , as illustrated by vegetation patches in arid regions @xcite . on the theoretical side ,
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Suppose that you have an abstract for a scientific paper: in this paper we use a splitting technique to develop new multiscale basis functions for the multiscale finite element method ( msfem ) .
the multiscale basis functions are iteratively generated using a green s kernel .
the green s kernel is based on the first differential operator of the splitting .
the proposed msfem is applied to deterministic elliptic equations and stochastic elliptic equations , and we show that the proposed msfem can considerably reduce the dimension of the random parameter space for stochastic problems . by combining the method with sparse grid collocation methods , the need for a prohibitive number of deterministic solves is alleviated .
we rigorously analyze the convergence of the proposed method for both deterministic and stochastic elliptic equations .
computational complexity discussions are also offered to supplement the convergence analysis .
a number of numerical results are presented to confirm the theoretical findings .
multiscale finite element methods , green s function , stochastic elliptic equations , reduction of parameter space dimension 65n15 , 65n30 , 65n99 .
And you have already written the first three sentences of the full article: many fundamental and practical scientific problems involve a wide range of length scales .
typical examples may include subsurface flows and geophysical domains with microscopic structures . because there exist both natural randomness and lack of knowledge about the physical properties , it is often necessary to incorporate uncertainties into the model inputs .
one way to address the uncertainties is to model the random inputs as a random field / process , and in turn , such problems are often modeled as stochastic partial differential equations ( spdes ) . then the model s output can be accurately predicted by efficiently solving the associated spdes ..
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it is challenging to solve the spdes when the random inputs vary over multiple scales in space and contain inherent uncertainties .
the interest in developing stochastic multiscale methods for the spdes has steadily grown in recent years ( see e.g. , @xcite ) .
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Suppose that you have an abstract for a scientific paper: we calculate strange star properties , using large @xmath0 approximation with built - in chiral symmetry restoration ( csm ) .
we used a relativistic hartree fock mean field approximation method , using a modified richardson potential with two scale parameters @xmath1 and @xmath2 , to find a new set of equation of state ( eos ) for strange quark matter .
we take the effect of temperature ( t ) on gluon mass , in addition to the usual density dependence , and find that the transition t from hadronic matter to strange matter is 80 mev .
therefore formation of strange stars may be the only signal for formation of qgp with asymptotic freedom ( af ) and csm . .
And you have already written the first three sentences of the full article: there have been some exciting developments recently since the four groups brahms , phenix , phobos and star have analyzed rhic data .
these four groups reporting on rhic , with gold on gold , show that quark gluon plasma with asymptotic freedom and chiral symmetry restoration may never be realized in rhic although a non - hadronic phase is reached .
unfortunately , their conclusions are negative in so far as finding of asymptotically free chirally symmetric qcd state is not possible in these reactions - although a new phase is formed which is quite distinct from the hadronic phase ..
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this phase is strongly interacting and is not fully understood theoretically but it is certainly not qgp with asymptotic freedom and chiral symmetry restoration .
two decades back witten@xcite has proposed the existence of strange matter and strange stars , and even today it is still difficult to prove or disprove the existence of a state of strange quark matter in its purest form . in literature , there are several eoss for strange quark matter , starting from the bag model @xcite to the recent models like the mean field model with interacting quarks@xcite , the perturbative qcd approach@xcite , chiral chromodielectric model@xcite , dyson - schwinger model@xcite , etc .
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Suppose that you have an abstract for a scientific paper: we study the energetics of the accretion - induced outflow and then plausible jet around black holes / compact objects using a newly developed disc - outflow coupled model .
inter - connecting dynamics of outflow and accretion essentially upholds the conservation laws .
the energetics depend strongly on the viscosity parameter @xmath0 and the cooling factor @xmath1 which exhibit several interesting features .
the bolometric luminosities of ultra - luminous x - ray binaries ( e.g. ss433 ) and family of highly luminous agns and quasars can be reproduced by the model under the super - eddington accretion flows . under appropriate conditions , low - luminous agns ( e.g. sagittarius @xmath2 )
also fit reasonably well with the luminosity corresponding to a sub - eddington accretion flow with @xmath3 .
keywords : accretion , accretion disc black hole physics x - rays : binaries galaxies : jets galaxies : nuclei [ firstpage ] .
And you have already written the first three sentences of the full article: extremely high resolution observations of the powerful extragalactic double radio sources @xcite reveal that they are formed by well - collimated outflows or jets that continuously emerge from the nuclear region of the host active galaxies ( agns ) or quasars , believed to harbor supermassive black holes . similarly micro - quasars @xcite discovered in recent times reveal that outflows are generated from stellar mass black holes ( or black holes candidates ) . the well - collimated outflow in ss433 observed for several decades , which is our galactic , persistent , super - critical accretor , is an well known evidence of cosmic jet @xcite .
further , highly collimated line jets are seen in young stellar objects @xcite .
relativistic jets are also observed in neutron star low mass x - ray binaries ( lmxbs ) @xcite ..
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the outflows / jets extract matter , energy and momentum from the accretion disc that forms around the compact object , and thus the dynamics of outflow leading to jet is intrinsically coupled with the accretion dynamics through the conservation laws .
also several observations ( precisely the simultaneous observations of disc and jet ; see e.g. ghosh & mukhopadhyay 2009 , and references therein ) reveal that accretion processes and outflows are strongly correlated and they eventually control the accretion process , precisely , the accretion dynamics in the vicinity of the central star . the relativistic outflowing matter , in the case of quasars or micro - quasars , should indeed come only from the inner region of the accretion disc .
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Suppose that you have an abstract for a scientific paper: properties of the depleted heisenberg spin ladder material series ( c@xmath0h@xmath1n)@xmath2cu@xmath3zn@xmath4br@xmath5 have been studied by the combination of magnetic measurements and neutron spectroscopy .
disorder - induced degrees of freedom lead to a specific magnetic response , described in terms of emergent strongly interacting `` spin island '' objects .
the structure and dynamics of the spin islands is studied by high - resolution inelastic neutron scattering .
this allows to determine their spatial shape and to observe their mutual interactions , manifested by strong spectral in - gap contributions . in the solid state
, even weak perturbations may lead to qualitatively new physics described in terms of entirely new emergent degrees of freedom and quasiparticles @xcite .
one such perturbation , known to open the door to a variety of novel and competing ground states and rich phase diagrams , is structural or chemical disorder @xcite .
an exciting example of disorder - induced emergent degrees of freedom are the _
magnetic _ objects that appear upon the introduction of _ non - magnetic _ impurities in gapped quantum - disordered antiferromagnets ( afs ) @xcite . these entities may be understood as spins released from non - magnetic af singlets by removing their partner spins .
the short - range correlations in the underlying quantum af spread these spin degrees of freedom over extended regions ( `` spin - islands '' ) around each impurity site @xcite .
the size of the spin islands is controlled by the correlation length in the parent system , and may be as large as dozens of nanometers . due to their partial overlap ,
these spin islands interact .
the original quantum af thus acts as a `` medium '' that hosts a new magnetic system of _ mesoscopic _ objects and carries interactions between them . due to these interactions
, the emergent system may have its own unique correlations and dynamics .
the impurity - induced formation of localized @xmath6 spin objects has....
And you have already written the first three sentences of the full article: single crystals of ( c@xmath0h@xmath1n)@xmath2cu@xmath3zn@xmath4br@xmath5 were grown from solution by the temperature gradient method @xcite , according to the same procedure as for the original material ( c@xmath0h@xmath1n)@xmath2cubr@xmath5 @xcite but with replacement of the relevant amount @xmath18 of cubr@xmath2 by znbr@xmath2 . for the magnetic measurements
single crystals with typical masses of 15 mg were used .
the measurements were carried out with the help of a standard quantum design magnetic properties measurement system ( mpms - xl squid magnetometer ) . for measurements below 1.7 k ,.
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the @xmath68he cryostat insert for mpms ( iquantum ihelium3 ) was employed .
for all the samples , the magnetic field was applied along the @xmath69 axis of the structure . for the synthesis of single crystals for neutron scattering ,
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Suppose that you have an abstract for a scientific paper: we present the results from a series of collisionless @xmath0-body simulations of major mergers of galaxy dark matter haloes with density profiles having either inner cusps or cores .
our simulations range from @xmath1 to @xmath2 particles , allowing us to probe the phase - space distribution of dark matter particles in the innermost regions ( less than 0.005 virial radii ) of cold dark matter haloes , a subject of much recent debate .
we find that a major merger of two cored haloes yields a cored halo and does not result in a cuspy profile seen in many cosmological simulations .
this result is unchanged if we consider mergers with parent mass ratios of 3:1 instead of 1:1 .
mergers of a cuspy halo with either a cored halo or a second cuspy halo of equal mass , on the other hand , produce cuspy haloes with a slightly reduced inner logarithmic slope .
cuspy haloes , once formed , therefore appear resilient to major mergers .
we find the velocity structure of the remnants to be mildly anisotropic , with a maxwellian velocity distribution near the centre but not in the outer portions of the final haloes .
violent relaxation is effective only during the early phase of mergers , with phase mixing likely to be the dominant relaxation process at late times .
[ firstpage ] galaxies : haloes dark matter methods : @xmath0-body simulations .
And you have already written the first three sentences of the full article: in the currently favored cosmological constant plus cold dark matter ( @xmath3cdm ) model of cosmology , structure forms hierarchically : small dark matter haloes collapse at high redshifts , while larger and more massive objects form through a series of minor mergers that accrete smaller mass haloes and major mergers with comparable mass haloes . since dark matter haloes provide the gravitational potential wells necessary for galaxy formation @xcite , a detailed understanding of the effects of mergers is necessary in order to test models of galaxy formation and evolution within the @xmath3cdm paradigm .
recent numerical studies indicate that the hierarchical build - up process results in haloes with significant substructure populations : hundreds to thousands of subhaloes to the smallest resolvable mass scales appear to reside within galaxy sized haloes , comprising approximately 10% of a halo s mass @xcite .
a number of recent papers have investigated the evolution and detailed properties of the substructure using both semi - analytic models and numerical simulations ..
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depending on factors such as the relative mass , pericentric distance , and halo concentration , the orbits and masses of the subhaloes can be strongly affected by dynamical friction and tidal stripping ( e.g. @xcite ) .
dense subhaloes that survive the tidal process can sink to the centre of the parent halo , impacting its inner structure ( e.g. @xcite ) .
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Suppose that you have an abstract for a scientific paper: the relationship between abstract interpretation and partial deduction has received considerable attention and ( partial ) integrations have been proposed starting from both the partial deduction and abstract interpretation perspectives . in this work
we present what we argue is the first fully described generic algorithm for efficient and precise integration of abstract interpretation and partial deduction . taking as starting point state - of - the - art algorithms for context - sensitive , polyvariant abstract interpretation and ( abstract ) partial deduction , we present an algorithm which combines the best of both worlds .
key ingredients include the accurate success propagation inherent to abstract interpretation and the powerful program transformations achievable by partial deduction . in our algorithm ,
the calls which appear in the analysis graph are not analyzed w.r.t . the original definition of the procedure but w.r.t .
_ specialized definitions _ of these procedures .
such specialized definitions are obtained by applying both unfolding and abstract executability .
our framework is parametric w.r.t .
different control strategies and abstract domains . different combinations of such parameters correspond to existing algorithms for program analysis and specialization .
simultaneously , our approach opens the door to the efficient computation of strictly more precise results than those achievable by each of the individual techniques .
the algorithm is now one of the key components of the ciaopp analysis and specialization system . .
And you have already written the first three sentences of the full article: [ sec : motivation ] the relationship between abstract interpretation @xcite and partial evaluation @xcite has received considerable attention ( see for example @xcite and their references ) . in order to motivate and illustrate our proposal for an integration of abstract interpretation and partial evaluation , we use the running example of fig . [ lst : running - ex ] .
it is a simple ciao program which uses peano s arithmetic .
we use the ciao assertion language in order to provide precise descriptions on the initial call patterns . in our case , the ` entry ` declaration is used to inform that all calls to the only exported predicate ( i.e. , ` main/2 ` ) will always be of the form @xmath0 with @xmath1 ground and @xmath2 a variable ..
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the predicate ` main/2 ` performs two calls to predicate ` formula/2 ` , which contains mode tests ` ground(x ) ` and ` var(w ) ` on its input arguments .
a call ` formula(x , w ) ` returns @xmath3 .
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Suppose that you have an abstract for a scientific paper: the specific thermal enthalpy of a moist - air parcel is defined analytically following a method in which specific moist entropy is derived from the third law of thermodynamics .
specific thermal enthalpy is computed by integrating specific heat content with respect to absolute temperature and including the impacts of various latent heats ( i.e. , solid condensation , sublimation , melting , and evaporation ) .
it is assumed that thermal enthalpies can be set to zero at @xmath0 k for the solid form of the main chemically inactive components of the atmosphere ( solid-@xmath1 oxygen and nitrogen , hexagonal ice ) .
the moist thermal enthalpy is compared to already existing formulations of moist static energy ( mse ) .
it is shown that the differences between thermal enthalpy and the thermal part of mse may be quite large .
this prevents the use of mse to evaluate the enthalpy budget of a moist atmosphere accurately , a situation that is particularly true when dry - air and cloud parcels mix because of entrainment / detrainment processes along the edges of cloud .
other differences are observed when mse or moist - air thermal enthalpy is plotted on a psychrometric diagram or when vertical profiles of surface deficit are plotted .
_ paper accepted for publication in the .
_ + _ last revised version in january 2014 . _
+ _ : [email protected]_ .
And you have already written the first three sentences of the full article: this paper shows that local values of internal energy and enthalpy within a moist atmosphere can be better computed so as to study the energy and enthalpy directly for global / local domains .
difficulties encountered in the past were due to a paradox : the budget equation of temperature was easier to compute than the local values of enthalpy , whereas it was easier to compute the local values of entropy than to solve the budget equation .
one example of this paradox is given by the conservation or imbalance properties of internal energy @xmath2 ( see appendix a ) or for the enthalpy @xmath3 ..
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it is important to evaluate observed changes in radiative forcing and imbalance properties for energy fluxes , in order i ) to properly assess observed climate change impacts and ii ) to improve our ability to understand energy changes in the climate system at regional scales . in studying the conservation of energy in nwp models and gcms , it is common to assess global energy fluxes from the surface to the top of the atmosphere using re - analysis products .
conservation and/or imbalance properties are thus currently monitored via the computation of fluxes of energy at the surface and the top of the atmosphere rather than by directly computing regional or global integrals of energy throughout the atmosphere . ]
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Suppose that you have an abstract for a scientific paper: the multistate potts models on two - dimensional hyperbolic lattices are studied with respect to various boundary effects .
the free energy is numerically calculated using the corner transfer matrix renormalization group method .
we analyze phase transitions of the potts models in the thermodynamic limit with respect to contracted boundary layers .
a _
false _ phase transition is present even if a couple of the boundary layers are contracted .
its significance weakens , as the number of the contracted boundary layers increases , until the correct phase transition ( deep inside the bulk ) prevails over the _
false _ one . for this purpose
we derive a thermodynamic quantity , the so - called _ bulk excess _
free energy , which depends on the contracted boundary layers and memorizes additional boundary effects .
in particular , the magnetic field is imposed on the outermost boundary layer . while the boundary magnetic field does not affect the second - order phase transition in the bulk if suppressing all the boundary effects on the hyperbolic lattices , the first - order ( discontinuous ) phase transition is significantly sensitive to the boundary magnetic field .
contrary to the phase transition on the euclidean lattices , the discontinuous phase transition on the hyperbolic lattices can be continuously controlled ( within a certain temperature coexistence region ) by varying the boundary magnetic field . .
And you have already written the first three sentences of the full article: negatively curved surfaces have been studied experimentally including lattice dislocations of solid - state crystals with non - euclidean properties , e.g. , in various magnetic nanostructures @xcite , or in materials showing a conical geometry @xcite . on the other hand ,
theoretical interest has been focused on the geometry of anti de sitter ( ads ) space @xcite and the complex ( e.g. neural ) networks @xcite .
the nontrivial boundary structure of finite hyperbolic spaces plays an essential role in the analysis of ads space by means of entanglement entropy @xcite ..
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the mutual relations among condensed - matter physics , the general theory of relativity , and the conformal field theory ( cft ) enrich the interdisciplinary research , such as ads - cft correspondence @xcite . in 2007 , we proposed a way to generalize the corner transfer matrix renormalization group ( ctmrg ) algorithm to a simple hyperbolic surface @xcite .
the current study extends our recent generalization to arbitrary regular hyperbolic geometry @xcite , and we focus on the complexity of the boundary effects of hyperbolic lattice geometry . because no satisfactory analytic studies are available yet , we analyze multistate spin models on hyperbolic lattices numerically . in particular , we focus on phase transitions , which require special treatment because of the non - negligible boundary effect , as they have been suppressed thus far .
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Suppose that you have an abstract for a scientific paper: the random - to - top and the riffle shuffle are two well - studied methods for shuffling a deck of cards .
these correspond to the symmetric group @xmath0 , i.e. , the coxeter group of type @xmath1 . in this paper
, we give analogous shuffles for the coxeter groups of type @xmath2 and @xmath3 .
these can be interpreted as shuffles on a `` signed '' deck of cards . with these examples as motivation , we abstract the notion of a shuffle algebra which captures the connection between the algebraic structure of the shuffles and the geometry of the coxeter groups .
we also briefly discuss the generalisation to buildings which leads to @xmath4-analogues . .
And you have already written the first three sentences of the full article: in a recent work , ken brown used algebraic methods to analyse random walks on a class of semigroups called `` left - regular bands '' . these walks include the hyperplane chamber walks of bidigare , hanlon , and rockmore . in this paper , we look at the special case of reflection arrangements that arise in the study of coxeter groups .
the random walks that we look at can be thought of as shuffles on the coxeter group .
the motivating examples are the riffle shuffle and the random - to - top shuffle on a deck of @xmath5 cards ..
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these correspond to the symmetric group @xmath0 , i.e. , the coxeter group of type @xmath1 .
the only coxeter groups that we deal with are the ones of type @xmath1 , @xmath2 and @xmath3 .
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Suppose that you have an abstract for a scientific paper: we study a method to induce resonant transitions between antihydrogen ( @xmath0 ) quantum states above a material surface in the gravitational field of the earth .
the method consists in applying a gradient of magnetic field which is temporally oscillating with the frequency equal to a frequency of a transition between gravitational states of antihydrogen .
corresponding resonant change in a spatial density of antihydrogen atoms can be measured as a function of the frequency of applied field .
we estimate an accuracy of measuring antihydrogen gravitational states spacing and show how a value of the gravitational mass of the @xmath0 atom can be deduced from such a measurement . .
And you have already written the first three sentences of the full article: precision tests of the equivalence principle ( ep ) in different physical phenomena is of fundamental interest .
this statement is especially valid for testing ep in case of a quantum motion of antiatoms .
detailed studies of gravitational properties of antimatter are planned by most groups involved in experiments with antihydrogen ( @xmath0 ) @xcite . here.
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we discuss a possibility of exploring gravitational states of @xmath0 @xcite with potentially very precise spectroscopic methods .
we study the behaviour of @xmath0 bounded in the gravitational field near a material surface under the influence of alternating magnetic field , with the frequency adjusted to induce resonance transitions between lowest gravitational states .
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Suppose that you have an abstract for a scientific paper: we review current understanding of the underlying , as opposed to the observed , pulsar population . the observed sample is heavily biased by selection effects , so that surveys see less than 10% of all potentially observable pulsars .
we compare various techniques used to correct the sample for these biases . by far
the most significant recent development has been the discovery of over 700 pulsars in the parkes multibeam ( pm ) survey .
this new sample is far less affected by selection effects and we use it to make a preliminary analysis of the galactic pulsar distribution , finding further evidence for a deficit of pulsars in the inner galaxy .
# 1_#1 _ # 1_#1 _ = # 1 1.25 in .125 in .25 in .
And you have already written the first three sentences of the full article: [ fig : selfx ] shows the current sample of 1300 pulsars in the atnf on - line catalogue ( hobbs et al .
these proceedings ) projected onto the galactic plane . rather than being distributed about the galactic centre , the majority of pulsars are local objects . far from being representative of the true population , this sample is heavily biased by a number of selection effects which we now outline below . * the inverse square law . *
like all astronomical sources , observed pulsars of a given luminosity @xmath0 are strongly selected by their apparent flux density , @xmath1 . for pulsars , which beam to a certain fraction @xmath2 of @xmath3 sr ..
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] , @xmath4 , where @xmath5 is the distance to the pulsar . since all pulsar surveys have some limiting flux density only those objects bright or close enough will be detectable . * the radio sky background .
* one limit to pulsar search sensitivities is the thermal noise in the receiver , i.e. the `` system temperature '' , @xmath6 . while every effort is made to minimize @xmath6 at the telescope , synchroton radiating electrons in the galactic magnetic field contribute significantly with a `` sky background '' component , @xmath7 . at observing frequencies @xmath8 ghz
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Suppose that you have an abstract for a scientific paper: a thorough understanding of jet quenching on the basis of multi - particle final states and jet observables requires new theoretical tools .
this talk summarises the status and propects of the theoretical description of jet quenching in terms of monte carlo generators . .
And you have already written the first three sentences of the full article: the motivations for studying jet observables instead of single - inclusive observables are manifold and shall not be discussed extensively here . instead , only two important points will be mentioned .
firstly , it has turned out that single - inclusive observables do not fully constrain the analytical models for partonic energy loss .
the nuclear modification factor for instance is described by all models equally well albeit with very different transport coefficients@xcite ..
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the benefit of studying sub - leading fragments and jet observables is that these are much more discriminating .
the downside is that they are not well modelled by the existing analytical calculations and new theoretical tools are needed .
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Suppose that you have an abstract for a scientific paper: we propose and develop a formalism to describe and constrain statistically anisotropic primordial perturbations . starting from a decomposition of the primordial power spectrum in spherical harmonics
, we find how the temperature fluctuations observed in the cmb sky are directly related to the coefficients in this harmonic expansion .
although the angular power spectrum does not discriminate between statistically isotropic and anisotropic perturbations , it is possible to define analogous quadratic estimators that are direct measures of statistical anisotropy . as a simple illustration of our formalism we test for the existence of a preferred direction in the primordial perturbations using full - sky cmb maps .
we do not find significant evidence supporting the existence of a dipole component in the primordial spectrum . .
And you have already written the first three sentences of the full article: at the time einstein decided to apply his equations to the universe , observational data in cosmology was rather scarce , if not inexistent .
hence , instead of relying on observations to constrain the spacetime metric , he postulated the
cosmological principle , " the isotropy and homogeneity of the universe . similarly , guided by theoretical prejudice.
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, einstein assumed that the universe was static , which , incidentally , is what forced him to introduce a cosmological constant in his equations .
it turns out that the universe is actually homogeneous and isotropic on large scales , as confirmed , for example , by the homogeneity of the distribution of luminous red galaxies @xcite and the isotropy of the cosmic microwave background @xcite .
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Suppose that you have an abstract for a scientific paper: within the broad research scenario of quantum secure communication , two - way quantum key distribution ( twqkd ) is a relatively new proposal for sharing secret keys that is not fully explored yet .
we analyse the security of twqkd schemes that use qubits prepared in non - orthogonal states to transmit the key . investigating protocols that employ an arbitrary number of bases for the channel preparation , we show , in particular , that the security of the lm05 protocol can not be improved by the use of more than two preparation bases . we also provide
a new proof of unconditional security for a deterministic twqkd protocol recently proposed [ phys .
rev .
a * 88 * , 062302 ( 2013 ) ] .
in addition , we introduce a novel deterministic protocol named `` twqkd six - state '' and compute an analytical lower bound ( which can be tightened ) for the maximum amount of information that an eavesdropper could extract in this case .
an interesting advantage of our approach to the security analysis of twqkd is the great simplicity and transparency of the derivations . .
And you have already written the first three sentences of the full article: quantum key distribution ( qkd ) harnesses the laws of quantum mechanics to distribute a secret key with a security level unachievable by classical means @xcite . in a qkd protocol
two parties , commonly called alice ( message sender ) and bob ( message receiver ) , want to establish a secret key between them , by sending quantum and classical information through an insecure channel .
the communication channel can be spied by a powerful eavesdropper , typically called eve , who is assumed to be technologically much more advanced than alice and bob ..
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thus , eve can listen all the transmitted classical messages and manipulate the quantum information at her own will , in principle , being only limited by the laws of quantum physics .
however , this manipulation unavoidably introduces perturbations of quantum nature , which may be detected by the communication partners ( alice and bob ) , depending on the features of the communication protocol they are employing . in such a way , they are able to determine how much information was leaked and keep only the secure part in the final secret key . standard qkd protocols ( one - way protocols ) , such as bb84 @xcite , six - state @xcite and and sarg04 @xcite , use an encoding method that prevents bob to decode the information in a deterministic way .
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Suppose that you have an abstract for a scientific paper: we have imaged with _ hst _
s wfc3/uvis the central @xmath0 region of the giant elliptical galaxy m 87 , using the ultraviolet filter f275w . in combination with archival acs / wfc data taken through the f606w and f814w filters , covering the same field , we have constructed integrated - light uv@xmath1optical colors and magnitudes for 1460 objects ,
most of which are believed to be globular clusters belonging to m 87 .
the purpose was to ascertain whether the multiple - populations syndrome , ubiquitous among galactic globular clusters ( gcs ) , exists also among the m 87 family of clusters . to achieve this goal , we sought those gcs with exceptionally blue uv - to - optical colors , because helium - enriched sub - populations produce a horizontal - branch morphology that is well populated at high effective temperature . for comparison , integrated , synthetic uv@xmath1optical and purely optical colors and magnitudes
have been constructed for 45 galactic gcs , starting from individual - star photometry obtained with the same instruments and the same filters .
we identify a small group of m 87 clusters exhibiting a radial uv@xmath1optical color gradient , representing our best candidate gcs hosting multiple populations with extreme helium content .
we also find that the central spatial distribution of the bluer gcs is flattened in a direction parallel to the jet , while the distribution of redder gcs is more spherical .
we release to the astronomical community our photometric catalog in f275w , f606w and f814w bands and the high - quality image stacks in the same bands . .
And you have already written the first three sentences of the full article: in recent years the discovery and characterization of multiple stellar populations in globular clusters ( gcs ) has given a new impetus to gc studies , opening entirely new scenarios for their formation .
first came the discovery that the main sequence ( ms ) of @xmath2 cen splits into two , distinct parallel sequences ( bedin et al .
subsequent spectroscopic analysis showed that , instead of a lower metal abundance , the blue sequence has a _ higher _ metallicity compared to the red sequence , inescapably demanding that blue ms stars must be greatly enriched in helium ( piotto et al ..
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2005 : see also norris 2004 ) .
this is now quantified in @xmath3 ( king et al .
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Suppose that you have an abstract for a scientific paper: we develop a physical model of the zodiacal cloud incorporating the real dust sources of asteroidal , cometary , and kuiperoidal origin . using the inferred distribution of the zodiacal dust ,
we compute its thermal emission and scattering at several wavelengths ( 1.25 , 5 , and 20 @xmath0 m ) as a function of ngst location assumed to be at 1 au or 3 au . areas on the sky with a minimum of zodiacal light are determined . .
And you have already written the first three sentences of the full article: improvements in the zodiacal light emission and scattering to be given by space observations at 3 au , compared with observations near the earth , were discussed by _ mather and beichman ( 1996)_. unfortunately , a rather accurate multi - parametric model of the zodiacal brightness derived by _ kelsall et al .
( 1998 ) _ from the cobe data can not be reliably extrapolated to heliocentric distances as large as 3 au .
we have developed a physical model of the zodiacal cloud incorporating the real dust sources of asteroidal and cometary origin , which makes it possible to evaluate quantitatively the zodiacal light emission and scattering throughout the solar system ( _ gorkavyi et al ..
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1997a _ ) .
this model considerably improves our previous ` reference model ' based on the use of the continuity equation for distribution function of dust particles ( _ gorkavyi et al .
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Suppose that you have an abstract for a scientific paper: the sun is used as the fundamental standard in chemical abundance studies , thus it is important to know whether the solar abundance pattern is representative of the solar neighborhood .
albeit at low precision ( 0.05 - 0.10 dex ) the sun seems to be a typical solar - metallicity disk star , at high precision ( 0.01 dex ) its abundance pattern seems abnormal when compared to solar twins .
the sun shows a deficiency of refractory elements that could be due to the formation of terrestrial planets . the formation of giant planets may also introduce a signature in the chemical composition of stars .
we discuss both planet signatures and also the enhancement of neutron - capture elements in the solar twin 18 sco . .
And you have already written the first three sentences of the full article: in previous studies the question of whether the sun has a normal composition has been discussed in detail ( gustafsson 1998 , 2008 ; gustafsson et al .
2010 ; allende prieto 2008 , 2010 ) .
it has been recognized that earlier studies obtained discrepant results regarding possible chemical abundance anomalies in the sun , probably due to relatively large ( 0.05 - 0.10 dex ) abundance uncertainties ..
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an illustrative example is the conflicting results found for the [ o / fe ] ratio in solar - metallicity thin disk dwarfs . in the seminal study by edvardsson et al .
( 1993 ) , the [ o / fe ] ratio around [ fe / h ] = 0 in disk stars was found to be somewhat subsolar , meaning that the sun could be either somewhat oxygen - rich or somewhat iron - poor , relative to disk stars .
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Suppose that you have an abstract for a scientific paper: the semiclassical wigner treatment of bimolecular collisions , proposed by lee and scully on a partly intuitive basis [ j. chem .
phys .
73 , 2238 ( 1980 ) ] , is derived here from first principles .
the derivation combines e. j. heller s ideas [ j. chem .
phys .
62 , 1544 ( 1975 ) ; 65 , 1289 ( 1976 ) ; 75 , 186 ( 1981 ) ] , the backward picture of molecular collisions [ l. bonnet , j. chem . phys . 133 , 174108 ( 2010 ) ] and the microreversibility principle . .
And you have already written the first three sentences of the full article: quantum mechanical ( qm ) calculations of molecular reaction dynamics @xcite are generally much heavier than quasi - classical trajectory calculations @xcite , in particular for polyatomic processes @xcite .
hence , for several decades , intense researches aim at building semiclassical methods taking into account the largest quantum effects while keeping with the classical description of nuclear motions @xcite .
moreover , developping such methods naturally leads to shed light on the complex frontier between the quantum and classical descriptions of motion ..
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last but not least , semiclassical approaches may be used as powerful interpretative tools to rationalize the dynamics of molecular processes .
the semiclassical wigner treatment of bimolecular collisions proposed by lee and scully is among them @xcite . when applied to the collinear inelastic collision between he and h@xmath0 , or he and hbr , which involve strong quantum interferences and/or classically forbidden vibrational transitions , this approach leads to final state populations in very good agreement with exact quantum ones ( at least for the lowest vibrational states of the initial diatom ) , contrary to the quasi - classical trajectory ( qct ) method @xcite .
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Suppose that you have an abstract for a scientific paper: i give a synopsis , specifically aimed at nonexperts , of some of the recent developments in electroweak baryogenesis .
the focus of the talk is on the present status of electroweak baryogenesis in supersymmetric models , since this is a plausible and realistic possibility that is currently being probed by experimental searches for the higgs boson and the top squark .
the question of whether it is viable to have a period of color - breaking during the electroweak phase transition is also discussed .
-4 in .
And you have already written the first three sentences of the full article: the baryons within the observed universe appear to consist essentially only of matter and not antimatter .
there are no regions of gamma ray emission which would correspond to the collision between a galaxy made of normal matter with one made from antimatter , for instance .
moreover , the theory of big bang nucleosythesis gives predictions for the abundances of primordial helium ( both @xmath0he and @xmath1he ) , deuterium and lithium , if the ratio of baryons to photons in the universe is in the range @xmath2 if we do live in a universe with equal quantities of matter and antimatter , then the two must somehow be separated on distance scales greater than the present hubble length , that is , the size of the presently observable universe ..
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the simplest assumption is that indeed the whole universe has the same preponderance of matter over antimatter .
it is a deep mystery of cosmology why the abundance of baryons should be this peculiar number , @xmath3 , relative to the number of photons .
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Suppose that you have an abstract for a scientific paper: the quantum spin @xmath0 xxz chain with anisotropy parameter @xmath1 possesses a dynamic supersymmetry on the lattice .
this supersymmetry and a generalisation to higher spin are investigated in the case of open spin chains .
a family of non - diagonal boundary interactions that are compatible with the lattice supersymmetry and depend on several parameters is constructed .
the cohomology of the corresponding supercharges is explicitly computed as a function of the parameters and the length of the chain . for certain specific values of the parameters ,
this cohomology is shown to be non - trivial .
this implies that the spin - chain ground states are supersymmetry singlets .
special scalar products involving an arbitrary number of these supersymmetry singlets for chains of different lengths are exactly computed . as a physical application ,
the logarithmic bipartite fidelity of the open quantum spin @xmath0 xxz chain with @xmath1 and special diagonal boundary interactions is determined .
= 1 .
And you have already written the first three sentences of the full article: the spin @xmath0 xxz heisenberg chain is arguably one of the most important exactly solvable quantum models of interacting spins in one dimension .
one the one hand , its study has inspired the development of many modern techniques of quantum integrability such as the bethe ansatz @xcite , the quantum - inverse scattering method @xcite or the vertex - operator approach @xcite . on the other hand , it is related to a variety of physically interesting problems , most notably the theory of quantum magnetism @xcite . in this article , we study the open integrable xxz heisenberg chain with arbitrary spin @xmath2 @xcite .
we focus on a particular value of the anisotropy parameter where the spin chain exhibits an additional symmetry beyond its integrability : _ supersymmetry _ @xcite . for concreteness ,.
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let us consider the familiar case @xmath3 . for diagonal boundary fields
the spin - chain hamiltonian of a chain of length @xmath4 is given by @xmath5 where @xmath6 and @xmath7 denote the pauli matrices , @xmath8 the anisotropy parameter , and @xmath9 the boundary magnetic fields .
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Suppose that you have an abstract for a scientific paper: in this article , we construct the axialvector - diquark - scalar - diquark - antiquark type and the axialvector - diquark - axialvector - diquark - antiquark type interpolating currents , and study the @xmath0 hidden - charm pentaquark states with the strangeness @xmath1 systematically using the qcd sum rules .
the predicted masses of the pentaquark states @xmath2 , @xmath3 and @xmath4 are compatible with the experimental value @xmath5 from the lhcb collaboration , more experimental data are still needed to identify the @xmath6 unambiguously .
+ zhi - gang wang + department of physics , north china electric power university , baoding 071003 , p. r. china pacs number : 12.39.mk , 14.20.lq , 12.38.lg key words : pentaquark states , qcd sum rules .
And you have already written the first three sentences of the full article: in 2015 , the lhcb collaboration studied the @xmath7 decays with the data sample corresponds to an integrated luminosity of @xmath8 acquired with the lhcb detector from 7 and 8 tev @xmath9 collisions , and observed two pentaquark candidates @xmath6 and @xmath10 in the @xmath11 invariant mass distributions with the significances of more than 9 standard deviations @xcite .
they performed the amplitude analysis on all relevant masses and decay angles of the six - dimensional data using the helicity formalism and breit - wigner amplitudes to describe all resonances .
the breit - wigner masses and widths are @xmath5 , @xmath12 , @xmath13 , and @xmath14 , respectively ..
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the preferred quantum numbers of the @xmath6 and @xmath10 are @xmath15 and @xmath16 , respectively .
recently , the lhcb collaboration inspected the @xmath7 decays for the presence of @xmath11 or @xmath17 contributions with minimal assumptions about @xmath18 contributions ( such as their number , their resonant or nonresonant nature , or their lineshapes ) , and observed that at more than 9 standard deviations the @xmath7 decays can not be described with the @xmath18 contributions alone , and the @xmath11 contributions play a dominant role in this incompatibility , and obtained model - independent support for the evidences of the @xmath19 decays @xcite .
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Suppose that you have an abstract for a scientific paper: single crystals of fe@xmath0tas@xmath1 have been studied by using magneto - optical ( mo ) imaging and radio - frequency ( rf ) magnetic susceptibility , @xmath2 .
real time mo images reveal unusual , slow dynamics of dendritic domain formation , the details of which are strongly dependent upon magnetic and thermal history .
measurements of @xmath3 show well - defined , local moment ferromagnetic transition at @xmath4 k as well as thermal hysteresis for 50 k@xmath560 k. this temperature range corresponds to the domain formation temperature as determined by mo .
together these observations provide strong evidence for local moment ferromagnetism in fe@xmath0tas@xmath1 crystals with large , temperature dependent magnetic anisotropy . .
And you have already written the first three sentences of the full article: the layered structure of the transition metal dichalcogenide tas@xmath1 permits the intercalation of other metal ions , nominally changing the formula to @xmath6tas@xmath1 . if @xmath7 is a 3@xmath8-transition metal , under certain circumstances long range magnetic order may occur .
the details of the order strongly depend on the type , @xmath7 , and amount , @xmath9 , of intercalated ion .
if @xmath10 fe , long range magnetic order is observed for @xmath11 ..
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further , for @xmath121/4 and 1/3 ordered superlattice form with basal plane axes a=2a@xmath13 and a=@xmath14a@xmath13 , respectively @xcite .
the magnetic ordering temperature is non - monotonic with doping concentration , reaching a maximum at approximately 155 k for @xmath15 @xcite .
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Suppose that you have an abstract for a scientific paper: we study the effect of a strong coupling field on the absorptive property of a ring cavity with two mirrors oscillating at slightly different frequencies to a weak probe field .
we observe double electromagnetically induced transparency windows separated by an absorption peak at line center in the output probe field under the action of a strong coupling field .
we find that increasing driving power can broaden the two transparency windows , which results in narrowing of the central absorption peak . at high driving power ,
the linewidth of the sharp central absorption peak is approximately equal to the mechanical linewidth .
we show the normal mode splitting in both the output probe field and the generated stokes field .
we also find that the suppression of the four - wave mixing process can be achieved on resonance . .
And you have already written the first three sentences of the full article: it is well - known that a @xmath0-type three - level atomic medium can become transparent to a weak probe field by applying a strong coupling field , which is the result of the destructive interference between two different excitation pathways to the upper level .
this is the phenomenon of electromagnetically induced transparency ( eit ) @xcite .
the eit has been shown to be important for various applications such as slow light @xcite , light storage @xcite , and so on . besides.
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, the studies of eit have been extended to multi - level atomic systems .
the double eit windows separated by a narrow absorption peak in the probe absorption spectrum have been observed in the four - level atomic systems @xcite .
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Suppose that you have an abstract for a scientific paper: we show that an upper limit of @xmath0 k on the peak brightness temperature for an incoherent synchrotron radio source , commonly referred to in the literature as an inverse compton limit , may not really be due to inverse compton effects .
we show that a somewhat tighter limit @xmath1 is actually obtained for the condition of equipartition of energy between radiating particles and magnetic fields which happens to be a configuration of minimum energy for a self - absorbed synchrotron radio source .
an order of magnitude change in brightness temperature from @xmath2 in either direction would require departures from equipartition of about eight orders of magnitude , implying a change in total energy of the system up to @xmath3 times the equipartition value
. constraints of such extreme energy variations imply that brightness temperatures may not depart much from @xmath2 .
this is supported by the fact that at the spectral turnover , brightness temperatures much lower than @xmath4 k are also not seen in vlbi observations .
higher brightness temperatures in particular , would require in the source not only many orders of magnitude higher additional energy for the relativistic particles but also many order of magnitude weaker magnetic fields .
diamagnetic effects do not allow such extreme conditions , keeping the brightness temperatures close to the equipartition value , which is well below the limit where inverse compton effects become important . .
And you have already written the first three sentences of the full article: kellermann & pauliny - toth ( 1969 ) first suggested that the observed upper limit on the maximum radio brightness temperatures of compact self - absorbed radio sources is an inverse compton limit .
they argued that at brightness temperature @xmath5 k energy losses of radiating electrons due to inverse compton effects become so large that these result in a rapid cooling of the system , thereby bringing the synchrotron brightness temperature quickly below this limit .
singal ( 1986 ) on the other hand derived a somewhat tighter upper limit @xmath6 k , without taking recourse to any inverse compton effects ..
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he used the argument that due to the diamagnetic effects the energy in the magnetic fields can not be less than a certain fraction of that in the relativistic particles and then an upper limit on brightness temperature close to the equipartition value follows naturally .
however bodo , ghisellini & trussoni ( 1992 ) pointed out that this limit on the magnetic field energy changes when the drift currents due to magnetic field gradients at the boundary are considered .
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Suppose that you have an abstract for a scientific paper: we perform sph+n - body cosmological simulations of massive disk galaxies , including a formalism for black hole seed formation and growth , and find that satellite galaxies containing supermassive black hole seeds are often stripped as they merge with the primary galaxy .
these events naturally create a population of `` wandering '' black holes that are the remnants of stripped satellite cores ; galaxies like the milky way may host 5 15 of these objects within their halos .
the satellites that harbor black hole seeds are comparable to local group dwarf galaxies such as the small and large magellanic clouds ; these galaxies are promising candidates to host nearby intermediate mass black holes . provided that these wandering black holes retain a gaseous accretion disk from their host dwarf galaxy , they give a physical explanation for the origin and observed properties of some recently discovered off - nuclear ultraluminous x - ray sources such as hlx-1 . .
And you have already written the first three sentences of the full article: recent evidence for the existence of intermediate mass black holes ( imbhs ) raises questions about how such objects might form and evolve .
imbh candidates exist in globular clusters @xcite , nearby bulgeless galaxies @xcite , and active galactic nuclei @xcite .
additionally , off - nuclear ultraluminous x - ray sources ( ulxs ) have become increasingly promising imbh candidates @xcite . a source of imbhs.
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may be the seeds of supermassive black holes ( smbhs ) formed at high redshift ; any seed that does not grow into a smbh would today be observed as an imbh . while the precise mechanism for seed black hole ( bh ) formation is unknown ,
there are several postulated theories .
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Suppose that you have an abstract for a scientific paper: constraints on the spin - averaged @xmath0 scattering length and effective range have been obtained from measurements of the @xmath1 reaction close to the production threshold by comparing model phase - space dalitz plot occupations with experimental ones .
the data fix well the position of the virtual bound state in the @xmath0 system . combining this with information from elastic @xmath0 scattering measurements at slightly higher energies , together with the fact that the hyperdeuteron is not bound , leads to a new determination of the low energy @xmath0 scattering parameters .
+ 0.86 cm 0.86 cm 1.8 cm 0.4 cm 0.42 cm 0.88 cm 0.42 cm 22.5 cm 15.05 cm 0.35 cm 4ex * low - energy * + * the * reaction * * + j.t .
balewski@xmath2 , a. budzanowski@xmath3 , c. goodman@xmath4 , d. grzonka@xmath5 , m. hofmann@xmath5 , l. jarczyk@xmath6 , a. khoukaz@xmath7 , k. kilian@xmath5 , t. lister@xmath7 , p. moskal@xmath8 , w. oelert@xmath5 , i.a .
pellmann@xmath9 , c. quentmeier@xmath7 , r. santo@xmath7 , g. schepers@xmath7 , t. sefzick@xmath5 , s. sewerin@xmath5 , j. smyrski@xmath6 , a. strzakowski@xmath6 , c. thomas@xmath7 , c. wilkin@xmath10 , m. wolke@xmath5 , p. wstner@xmath11 , d. wyrwa@xmath8 + _ @xmath3 institute of nuclear physics , cracow , poland _ + _ @xmath5 ikp , forschungszentrum jlich , germany _ + _ @xmath4 iucf , bloomington , indiana , usa _ + _ @xmath6 institute of physics , jagellonian university , cracow , poland _
+ _ @xmath7 ikp , westflische wilhelms universitt , mnster , germany _ + _ @xmath10 university college london , london wc1e 6bt , united kingdom _
+ _ @xmath11 zel , forschungszentrum jlich , germany _ * pacs : * 12.38.qk , 13.85.hd , 25.40.ve + * keywords : * scattering length , effective range , dalitz plot 4ex .
And you have already written the first three sentences of the full article: the existence of light hypernuclei , such as @xmath12he , shows the low energy @xmath13-@xmath14 interaction to be strongly attractive , though not sufficient to bind the two - baryon hyperdeuteron .
the @xmath13-@xmath14 interaction is of especial interest since it is influenced by the strange quark content of the @xmath13-hyperon .
however , in contrast to the nucleon - nucleon case , due to the short lifetime of the @xmath13 , direct measurements of low - energy @xmath13-@xmath14 scattering are sparse and the resulting parameters rather poorly known ..
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bubble chamber measurements @xcite , based on samples of a few hundred secondary events , have allowed determinations of the elastic cross section down to @xmath13 laboratory momenta @xmath15 mev / c . in the low energy region , where only @xmath16-waves are important , the spin - averaged total cross section is of the form @xmath17 here @xmath18 is the @xmath0 centre - of - mass momentum and @xmath19 and @xmath20 are , respectively ,
the @xmath16-wave scattering lengths and effective ranges in the @xmath0 spin - singlet and triplet states . separate values of these parameters have been claimed for the two spin states @xcite and these are shown in fig .
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Suppose that you have an abstract for a scientific paper: independent component analysis ( ica ) , as an approach to the blind source - separation ( bss ) problem , has become the de - facto standard in many medical imaging settings . despite successes and a large ongoing research effort , the limitation of ica to square linear transformations
have not been overcome , so that general infomax is still far from being realized . as an alternative
, we present feature analysis in medical imaging as a problem solved by helmholtz machines , which include dimensionality reduction and reconstruction of the raw data under the same objective , and which recently have overcome major difficulties in inference and learning with deep and nonlinear configurations .
we demonstrate one approach to training helmholtz machines , variational auto - encoders ( vae ) , as a viable approach toward feature extraction with magnetic resonance imaging ( mri ) data . .
And you have already written the first three sentences of the full article: feature selection is a central theme in analyzing many variants of magnetic resonance imaging ( mri ) data . supervised approaches that are highly capable of performing regression or classification , but do not rely on features , are at best specialized maps between input data and the output labels .
they lack the crucial component of `` inference '' to produce generalizations _ about _ the input data .
meanwhile , the inference process and ability to find generalizeable features or structure in the data is at the core of scientific discovery ; in mri research , such structures are necessary for the general goal of understanding the brain ..
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inferring the latent structure is generally the goal of unsupervised learning , which has had a wide success in analyzing mri data .
when combined with supervised learners , these structures have a diagnostic value . independent component analysis ( ica )
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Suppose that you have an abstract for a scientific paper: we investigate the properties of a closed - form analytic solution recently found by manko _
et al . _
( 2000b ) for the exterior spacetime of rapidly rotating neutron stars .
for selected equations of state we numerically solve the full einstein equations to determine the neutron star spacetime along constant rest mass sequences .
the analytic solution is then matched to the numerical solutions by imposing the condition that the quadrupole moment of the numerical and analytic spacetimes be the same . for the analytic solution we consider , such a matching condition can be satisfied only for very rapidly rotating stars . when solutions to the matching condition exist , they belong to one of two branches . for one branch the current octupole moment of the analytic solution
is very close to the current octupole moment of the numerical spacetime ; the other branch is more similar to the kerr solution .
we present an extensive comparison of the radii of innermost stable circular orbits ( iscos ) obtained with a ) the analytic solution , b ) the kerr metric , c ) an analytic series expansion derived by shibata and sasaki ( 1998 ) and d ) a highly accurate numerical code . in most cases
where a corotating isco exists , the analytic solution has an accuracy consistently better than the shibata - sasaki expansion .
the numerical code is used for tabulating the mass - quadrupole and current - octupole moments for several sequences of constant rest mass .
gravitation relativity stars : rotation stars : neutron .
And you have already written the first three sentences of the full article: the analytic description of the vacuum spacetime surrounding a rapidly rotating neutron star is still an open problem .
the analytic structure of the spacetime outside a slowly rotating star , and its relation to the kerr metric , has been well understood since the seminal works of hartle ( 1968 ) and hartle & thorne ( 1969 ) . on the other hand , numerical solutions of the einstein equations for stars rotating up to the mass - shedding limit
are now routinely obtained with a number of different methods , such as the komatsu , eriguchi and hachisu ( 1989 ) method ( see stergioulas 2003 , for an extensive comparison of the different existing numerical methods ) ..
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these numerical solutions are indeed useful for modelling astrophysical systems , for studying linear perturbations of rapidly rotating relativistic stars and as initial data for dynamical evolutions of spacetimes in numerical relativity ( see e.g. stergioulas & friedman 1998 , stergioulas , kluzniak & bulik 1999 , stergioulas & font 2001 ) . despite the availability of numerical solutions , a consistent analytic representation of the vacuum
metric outside a rapidly rotating neutron star is desirable for several reasons . in the first place ,
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11,474 |
Suppose that you have an abstract for a scientific paper: space - based photometric measurements first revealed low - amplitude irregularities in the pulsations of cepheid stars , but their origins and how commonly they occur remain uncertain . to investigate this phenomenon , we present _ most _ space telescope photometry of two cepheids .
v473 lyrae is a second - overtone , strongly modulated cepheid , while u trianguli australis is a cepheid pulsating simultaneously in the fundamental mode and first overtone .
the nearly continuous , high - precision photometry reveals alternations in the amplitudes of cycles in v473 lyr , the first case of period doubling detected in a classical cepheid . in u tra , we tentatively identify one peak as the @xmath0 or 0.61type mode often seen in conjunction with the first radial overtone in cepheids , but given the short length of the data , we can not rule out that it is a combination peak instead .
ground - based photometry and spectroscopy were obtained to follow two modulation cycles in v473 lyr and to better specify its physical parameters .
the simultaneous data yield the phase lag parameter ( the phase difference between maxima in luminosity and radial velocity ) of a second - overtone cepheid for the first time .
we find no evidence for a period change in u tra or an energy exchange between the fundamental mode and the first overtone during the last 50 years , contrary to earlier indications .
period doubling in v473 lyr provides a strong argument that mode interactions do occur in some cepheids and we may hypothesise that it could be behind the amplitude modulation , as recently proposed for blazhko rr lyrae stars .
[ firstpage ] stars : variables : cepheids stars : individual : v473 lyrae stars : individual : u tra .
And you have already written the first three sentences of the full article: classical cepheids , also known as @xmath1 cep - type stars or just cepheids , are population i instability strip pulsators crucial for understanding stellar structure and evolution .
most galactic cepheids pulsate in one mode with remarkably stable amplitudes and periods , although space - based photometry reveals that they are not entirely regular clocks .
observations with _.
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corot , kepler _ and _ most _ detect short - term , low - amplitude irregular variability or `` jitter '' in the pulsation cycles of some classical cepheids @xcite .
one exception is v473 lyrae ( @xmath2 = 19@xmath315@xmath45949 , @xmath5 = + 2755346 , @xmath6 = 6.18 mag ) , the only known classical cepheid in the galaxy that undergoes strong amplitude and phase modulations .
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Suppose that you have an abstract for a scientific paper: inspired by the recent creation of the honeycomb optical lattice and the realization of the mott insulating state in a square lattice by shaking , we study here the shaken honeycomb optical lattice . for a periodic shaking of the lattice , a floquet theory may be applied to derive a time - independent hamiltonian . in this effective description
, the hopping parameters are renormalized by a bessel function , which depends on the shaking direction , amplitude and frequency . consequently
, the hopping parameters can vanish and even change sign , in an anisotropic manner , thus yielding different band structures . here , we study the merging and the alignment of dirac points and dimensional crossovers from the two dimensional system to one dimensional chains and zero dimensional dimers .
we also consider next - nearest - neighbor hopping , which breaks the particle - hole symmetry and leads to a metallic phase when it becomes dominant over the nearest - neighbor hopping .
furthermore , we include weak repulsive on - site interactions and find the density profiles for different values of the hopping parameters and interactions , both in a homogeneous system and in the presence of a trapping potential .
our results may be experimentally observed by using momentum - resolved raman spectroscopy . .
And you have already written the first three sentences of the full article: the study of dirac points , i.e. the contact points between different energy bands with an approximate linear dispersion relation , has become a major issue since the experimental breakthrough in graphene - based electronics @xcite .
indeed , the low - energy electronic properties of graphene are governed by a pseudo - relativistic 2d dirac equation for massless fermions situated at the @xmath0 and @xmath1 corners of the brillouin zone @xcite .
the dirac points are topologically protected and a gap is opened only when the inversion symmetry of the lattice or the time - reversal symmetry are broken . the possibility to generate topological phase transitions in graphene - like systems has recently attracted a great deal of attention . within a tight - binding description , an anisotropy in the nearest - neighbor hopping parameters.
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makes the dirac points move away from the high - symmetry @xmath0 and @xmath1 points and , under appropriate conditions , merge at time - reversal invariant points in the first brillouin zone @xcite .
most saliently , this merging of dirac points is associated with a topological phase transition between a semimetallic phase and a gapped band - insulating phase .
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Suppose that you have an abstract for a scientific paper: we present and analyze observations of the quadruple lensed quasar q2237 + 0305 , obtained with the _ hst _ wfpc2 camera in the f336w and f300w filters .
twenty - five exposures were performed within 15 hours real time on 3 november 1995 . on a timescale of 34 hours , we observe no variation in component a of greater than 0.02 mag .
the other components remain constant over a period of 10 hours to within about 0.05 mag . in the final 5 hours
there is some evidence ( not conclusive ) for variation of component d by about 0.1 mag .
the exposures indicate that component a is brighter than component b by about 0.3 mag .
components c and d are fainter than component a by about 1.3 and 1.4 mag , respectively .
our results place an upper limit on any fifth ( central ) component of 6.5 mag fainter than component a. we determine the astrometric properties of the lens system , using only the exposures of the higher resolution planetary camera chip .
we measure the relative distances of the four components with high accuracy .
our values are systematically larger than those of other investigators ( by 0.1% to 2.0% ) .
we discuss the reasons why we believe our results are reliable . the f336w filter had been chosen for the observations because it corresponds to the redshifted ly-@xmath0 line of the quasar .
this filter might have allowed us to see extended ly-@xmath0 emission from the broad - line region ( blr ) of the quasar as ly-@xmath0 arcs , and hence to determine the physical size of the blr . however , the quasar components in this filter are consistent with a point source .
we conclude that there can not be any ly-@xmath0 feature in the image plane brighter than about 23.5 mag in f336w and further from the quasar core than 100 mas .
according to a lensing model by rix , scheider & bahcall ( 1992 ) , this would preclude any such features in the source plane further than 20 mas ( @xmath1 pc , assuming @xmath2 ) from the quasar core and brighter than 25 mag before magnification . .
And you have already written the first three sentences of the full article: the quasar q2237 + 0305 at redshift @xmath3 is gravitationally lensed by a nearby galaxy at @xmath4 ( huchra _ et al . _ 1985 ) .
the galaxy core lies nearly perfectly along the line of sight .
such a configuration results in a symmetric , cross - like arrangement of the four quasar component images , with relative separations in this case between 1.2 and 1.8 arcsec ..
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several facts make this lens system useful .
first , the closeness of the lensing spiral galaxy allows us to study it in great detail .
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Suppose that you have an abstract for a scientific paper: the interaction of high intensity laser radiation with underdense plasma may lead to the formation of electron vortices . though being quasistationary on an electron timescales , these structures tend to expand on a proton timescale due to coloumb repulsion of ions . using a simple analytical model of a stationary vortex as initial condition ,
2d pic simulations are performed .
a number of effects are observed such as vortex boundary field intensification , multistream instabilities at the vortex boundary , and bending of the vortex boundary with the subsequent transformation into smaller electron vortices .
keywords : relativistic laser plasmas , electron vortices , quasi - static magnetic field , particle - in - cell simulation .
And you have already written the first three sentences of the full article: formation of localized coherent structures during the interaction of intense laser pulses with plasmas is an important topic of the laser plasmas research , which is vital for diagnostic purposes in the experiments with laser ion acceleration , the fast ignition of controlled thermonuclear fusion , the investigation of warm dense matter , high energy density phenomena , and laboratory astrophysics ( see article @xcite and references therein ) .
when the laser pulse interacts with a homogeneous plasma region , we expect the pulse to penetrate inside the plasma and propogate with minor energy losses in case of underdense plasma .
quantitavely speaking , we expect laser pulse to penetrate if @xmath0 , where @xmath1 is the laser carrier frequency and @xmath2 is the electron plasma frequency ..
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the larger the @xmath3 ratio is , the lower is the laser pulse depletion rate .
however , eventually a finite duration laser pulse completely depletes due to stimulated raman scattering , various pulse filamentation instabilities and transformation to various localized coherent structures @xcite .
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11,478 |
Suppose that you have an abstract for a scientific paper: the key features of the matphot algorithm for precise and accurate stellar photometry and astrometry using discrete point spread functions are described . a discrete point spread function ( psf )
is a sampled version of a continuous psf which describes the two - dimensional probability distribution of photons from a point source ( star ) just above the detector .
the shape information about the photon scattering pattern of a discrete psf is typically encoded using a numerical table ( matrix ) or a fits image file .
discrete psfs are shifted within an observational model using a 21-pixel - wide damped sinc function and position partial derivatives are computed using a five - point numerical differentiation formula .
precise and accurate stellar photometry and astrometry is achieved with undersampled ccd observations by using supersampled discrete psfs that are sampled 2 , 3 , or more times more finely than the observational data .
the precision and accuracy of the matphot algorithm is demonstrated by using the c - language @xmath0 code to analyze simulated ccd stellar observations ; measured performance is compared with a theoretical performance model .
detailed analysis of simulated _ next generation space telescope _ observations demonstrate that millipixel relative astrometry and millimag photometric precision is achievable with complicated space - based discrete psfs .
[ firstpage ] techniques : image processing , photometric astrometry instrumentation : detectors methods : analytical , data analysis , numerical , statistical .
And you have already written the first three sentences of the full article: a point spread function ( psf ) is a continuous two - dimensional probability - distribution function which describes the scattering pattern of photons from a point source ( star ) . encoding a psf as a continuous mathematical function works well for many ground - based astronomical observations due to the significant blurring caused by turbulence in the earth s atmosphere and dome / telescope seeing .
ground - based psfs are typically characterized by having a lot of the power in their spatial - frequency distributions at low spatial frequencies .
space - based psfs frequently have significant amounts of power at higher spatial frequencies due to the lack of blurring caused by atmospheric turbulence ..
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adaptive optics can produce psfs with characteristics found in both uncorrected ground - based psfs and space - based psfs : low - spatial - frequency features ( e.g. , broad halos ) are frequently combined with high - spatial - frequency features ( e.g. , due to segmented mirrors ) .
some psf - fitting stellar photometric reduction programs describe the psf as a combination of continuous mathematical functions and a residual matrix which contains the difference between the mathematical model of the psf and an observed ( `` true '' ) psf .
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Suppose that you have an abstract for a scientific paper: theorems on zeroes of the truncated generating function in the complex plane are reviewed . when examined in the framework of a statistical model of high energy collisions based on the negative binomial ( pascal ) multiplicity distribution ,
these results lead to maps of zeroes of the grand canonical partition function which allow to interpret in a novel way different classes of events in pp collisions at lhc c.m.energies . .
And you have already written the first three sentences of the full article: following previous work @xcite , the multiplicity distribution ( md ) generating function in the dummy variable @xmath0 , @xmath1 has been recognised to be related to the grand canonical partition function of a system of @xmath2 particles in statistical mechanics when @xmath0 is identified with the fugacity variable ; @xmath3 is here the probability of detecting @xmath2 charged particles in full phase space ( @xmath4 ) and it is linked to the canonical partition function .
it has to be stressed that in a realistic experiment @xmath2 will never become infinity .
let us call @xmath5 the maximum finite value of @xmath2 which can be detected in an experiment ..
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the generating function @xmath6 in this case is reduced to a polynomial of degree @xmath5 in @xmath0 : @xmath7 let us now consider the algebraic equation @xmath8 in the complex @xmath0-plane . in the first place , notice that none of the roots @xmath9 @xmath10 of equation ( [ eq:3 ] ) can be real and positive , since the @xmath3 in ( [ eq:2 ] ) are positive for any @xmath2 . in the second place ,
recall that the @xmath5-truncated generating function ( as any polynomial ) can be factorised in terms of its roots as follows : @xmath11 by applying these considerations to phase transitions of a lattice gas ( and of the ising model ) , c.n .
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Suppose that you have an abstract for a scientific paper: the double pulsar system j0737@xmath03039 is not only a test bed for general relativity and theories of gravity , but also provides a unique laboratory for probing the relativistic winds of neutron stars .
recent x - ray observations have revealed a point source at the position of the j0737@xmath03039 system , but have failed to detect pulsations or orbital modulation .
here we report on _ chandra x - ray observatory _ high resolution camera observations of the double pulsar .
we detect deeply modulated , double - peaked x - ray pulses at the period of psr j0737@xmath03039a , similar in appearance to the observed radio pulses .
the pulsed fraction is @xmath1 .
purely non - thermal emission from pulsar a plausibly accounts for our observations .
however , the x - ray pulse morphology of a , in combination with previously reported spectral properties of the x - ray emission , allows the existence of both non - thermal magnetospheric emission and a broad sinusoidal thermal emission component from the neutron star surface .
no pulsations are detected from pulsar b , and there is no evidence for orbital modulation or extended nebular structure .
the absence of orbital modulation is consistent with theoretical expectations of a poynting - dominated relativistic wind at the termination shock between the magnetosphere of b and the wind from a , and with the small fraction of the energy outflow from a intercepted by the termination shock . .
And you have already written the first three sentences of the full article: binary neutron star systems are rare , and even among them , the double pulsar system j0737@xmath03039 is extraordinary , since both the neutron stars are detected as radio pulsars .
the system consists of the recycled 22.7 ms pulsar `` a '' @xcite and the young 2.8 s pulsar `` b '' @xcite , in a 2.454 hr eccentric ( @xmath2 ) binary orbit which happens to be nearly edge - on to us . as well as being a test bed for general relativity and theories of gravity ( e.g. * ? ? ?
* ) , the double pulsar is rich in observational phenomena , including a short eclipse of a by the magnetosphere of b and orbital modulation of the radio flux of b due to the influence of a @xcite ..
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the individual pulses from b show drifting features due to the impact of the low - frequency electromagnetic wave in the relativistic wind from a @xcite , while the eclipse of a is modulated at half the rotational period of b @xcite .
clearly , the two neutron stars have both gravitational and electromagnetic interactions with each other , and the double pulsar system should provide a unique laboratory to investigate the interactions between the magnetospheres and relativistic winds of the two pulsars . in this context , the detection of x - ray emission from the j0737@xmath03039 system @xcite is particularly exciting .
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Suppose that you have an abstract for a scientific paper: we present the latest results from a multi - epoch timing and spectral study of the transient anomalous x - ray pulsar xte j1810197 .
we have acquired seven observations of this pulsar with the newton x - ray multi - mirror mission ( xmm - newton ) over the course of two and a half years , to follow the spectral evolution as the source fades from outburst .
the spectrum is arguably best characterized by a two - temperature blackbody whose luminosities are decreasing exponentially with @xmath0 d and @xmath1 d , respectively .
the temperatures of these components are currently cooling at a rate of 22% per year from a nearly constant value recorded at earlier epochs of @xmath2 kev and @xmath3 kev , respectively .
the new data show that the temperature @xmath4 and luminosity of that component have nearly returned to their historic quiescent levels and that its pulsed fraction , which has steadily decreased with time , is now consistent with the previous lack of detected pulsations in quiescence .
we also summarize the detections of radio emission from xte j1810197 , the first confirmed for any axp .
we consider possible models for the emission geometry and mechanisms of xte j1810197 . 0.5 cm .
And you have already written the first three sentences of the full article: neutron star ( ns ) astronomy has been recently invigorated by the identification of a new class of magnetically dominated emitters .
known as anomalous x - ray pulsars ( axps ) and soft gamma - ray repeaters ( sgrs ) , these objects are apparently young , isolated neutron stars ( nss ) , whose properties differ markedly from those of the crab pulsar , previously considered prototypical of the young nss ( for a review see @xcite ) .
all axps and at least 3 of the 4 sgrs are identified as relatively slow ( @xmath5 s ) pulsars ..
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many are located at the centers of recognized , young supernova remnants ( snrs ) , directly associating them with their supernova explosions .
these objects emit predominantly at x - ray energies and are distinguished by their characteristic spectral signature .
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Suppose that you have an abstract for a scientific paper: motivated by the recent results of hansen et al .
( 2008 ) concerning a noticeable hemispherical power asymmetry in the wmap data on small angular scales , we revisit the dipole modulated signal model introduced by gordon et al .
( 2005 ) .
this model assumes that the true cmb signal consists of a gaussian isotropic random field modulated by a dipole , and is characterized by an overall modulation amplitude , @xmath0 , and a preferred direction , @xmath1 .
previous analyses of this model has been restricted to very low resolution ( ie .
, @xmath2 pixels , a smoothing scale of @xmath3 fwhm and @xmath4 ) due to computational cost . in this paper
, we double the angular resolution ( ie . , @xmath5 pixels and @xmath6 fwhm smoothing scale ) , and compute the full corresponding posterior distribution for the 5-year wmap data . the results from our analysis are the following : the best - fit modulation amplitude for @xmath7 and the ilc data with the wmap kq85 sky cut is @xmath8 , non - zero at @xmath9 , and the preferred direction points toward galactic coordinates @xmath10 .
the corresponding results for @xmath11 from earlier analyses was @xmath12 and @xmath13 .
the statistical significance of a non - zero amplitude thus increases from @xmath14 to @xmath9 when increasing @xmath15 from 40 to 64 , and all results are consistent to within @xmath16 .
similarly , the bayesian log - evidence difference with respect to the isotropic model increases from @xmath17 to @xmath18 , ranking as `` strong evidence '' on the jeffreys scale .
the raw best - fit log - likelihood difference increases from @xmath19 to @xmath20 .
similar , and often slightly stronger , results are found for other data combinations .
thus , we find that the evidence for a dipole power distribution in the wmap data increases with @xmath21 in the 5-year wmap data set , in agreement with the reports of hansen et al .
( 2008 ) . .
And you have already written the first three sentences of the full article: the question of statistical isotropy in the cosmic microwave background ( cmb ) has received much attention within the cosmological community ever since the release of the first - year wilkinson microwave anisotropy probe ( wmap ; bennett et al .
2003a ) in 2003 .
the reasons for this are two - fold . on the one hand ,.
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the current cosmological concordance model is based on the concept of inflation @xcite , which predicts a statistically homogeneous and isotropic universe .
since inflation has proved highly successful in describing a host of cosmological probes , most importantly the cmb and large - scale power spectra , this undeniably imposes a strong theoretical prior towards isotropy and homogeneity . on the other hand
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Suppose that you have an abstract for a scientific paper: we aim to characterize the current status of knowledge on the accuracy of open - cluster parameters such as the age , reddening and distance .
these astrophysical quantities are often used to study the global characteristics of the milky way down to very local stellar phenomena . in general , the errors of these quantities are neglected or set to some kind of heuristic standard value .
we attempt to give some realistic estimates for the accuracy of available cluster parameters by using the independent derived values published in the literature . in total ,
6437 individual estimates for 395 open clusters were used in our statistical analysis .
we discuss the error sources depending on theoretical as well as observational methods and compare our results with those parameters listed in the widely used catalogue by dias et al .
( 2002 ) .
in addition , we establish a list of 72 open clusters with the most accurate known parameters which should serve as a standard table in the future for testing isochrones and stellar models .
open clusters and associations : general .
And you have already written the first three sentences of the full article: the study of open clusters naturally introduces many advances , because they are physically related groups of stars held together by mutual gravitational attraction that were formed at roughly the same time from one large cosmic gas and dust cloud .
their evolutionary stages range from clouds where star formation still takes place at this moment to very old aggregates with turn - off points as late as solar type stars .
therefore , they represent samples of population i stars of constant age and comparable intrinsic chemical composition , best suited to study processes related to stellar evolution and formation , and to fix lines or loci in several most important astrophysical diagrams ..
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these procedures are statistical methods , for example fitting isochrones to determine the age , reddening , and distance of an open cluster , independent of individual peculiarities of members . as the open clusters drift along their orbits , they are excellent tracers for the global kinematics and dynamical characteristics of the milky way itself . however , some of their members escape the cluster , due to velocity changes in mutual close encounters or tidal forces in the galactic gravitational field .
the escaped stars continue to orbit on their own as field stars .
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Suppose that you have an abstract for a scientific paper: there is a class of supersymmetric models which is well - motivated by hints of evidence for susy and consistent with all existing data .
it is important to study the predictions of these models .
they are characterized by @xmath0 ( where @xmath1 and @xmath2 are neutralino and chargino mass eigenstates ) , @xmath3 , @xmath4 , and @xmath5 near 1 .
their lep signatures are mostly unusual .
most produced superpartners are invisible ! a good signature is two photons plus large missing energy .
there are also excess events at large recoil mass in the single photon plus nothing channel .
we list the main signatures for charginos , stops , etc . , which are also likely to be unconventional
. this class of models will be definitively tested at lep194 with 100 pb@xmath6 per detector , and almost definitively tested at lep184 .
# 1_t_#1 # 1_n_#1 # 1_#1 # 1#2_#1^#2 # 1_c_#1 # 1__#1 # 1#2_#1^#2 .
And you have already written the first three sentences of the full article: how might superpartners be detected if they exist ? they could be found in direct production at colliders as energy or luminosity is increased and a threshold is crossed in either . observing them
of course requires triggering on such events , and separating the signal from backgrounds . or , their effects could be seen from one - loop contributions .
most possible deviations from the , whether particle production or loop effects , could not be interpreted as signals of supersymmetry , since supersymmetric signals are strongly constrained as to which processes they can contribute to ..
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for example , susy production events should have missing energy ( assuming @xmath7-parity conservation ) , while deviations caused by loop effects should show up most strongly in processes such as @xmath8 and @xmath9 ( but _ not _ in @xmath10 quark asymmetries ) . in the past couple of years
some evidence of such effects has been reported@xcite .
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Suppose that you have an abstract for a scientific paper: in the present paper our aim is to introduce some models for the generalization of the kinetic theory of electrons and phonons ( ktep ) , as well as to study equilibrium solutions and their stability for the generalized ktep ( gktep ) equations .
we consider a couple of models , relevant to non standard quantum statistics , which give rise to inverse power law decays of the distribution function with respect to energy . in the case of electrons in a phonon background , equilibrium and stability
are investigated by means of lyapounov theory .
connections with thermodynamics are pointed out . .
And you have already written the first three sentences of the full article: as pointed out by koponen , fractal or inverse power law distributions are of interest in modeling various meaningful situations in solid state physics @xcite .
an example , treated in ref .
@xcite , is the thermalization of a nonequilibrium electron - phonon system . + until recently , however , there has been little guidance on how to generalize the kinetic theory of electrons and phonons obeying non - gibbsian statistics . in a very recent paper @xcite.
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a generalized kinetic theory for electrons and phonons has been proposed .
modified collision terms were introduced , in order to allow applications not only to electrons , but also to other particles ( obeying a general statistics ) which interact with a crystal lattice .
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Suppose that you have an abstract for a scientific paper: classical pion field similar to disoriented chiral condensate ( dcc ) is considered in the presence of the external source .
this field is similar to dcc in the sense that its isotopic orientation is specified with a single vector at the whole space .
we study the classical field solutions in the nonlinear sigma - model both in the chiral limit with massless pion and for the finite pion mass . in both cases
the field resembles the coulomb field of charged particle however the nonlinear pion interactions lead to the existence of several solutions . in the massless case and for the very small size of the source
there is the lot of classical solutions with finite discrete energies . in the more realistic situation of large nucleus ( heavy ion )
there are no stable solutions of the above type , but there is the possibility for the formation of the quasistationary states
. they can live for a long time slowly decaying through the emission of very soft pions .
the structure and the energies of these solutions is investigated numerically .
= 0.7 cm epsf 1.5 truecm * classical pion fields in the presence of source * + m.g.ryskin and a.g.shuvaev + theory department , st.petersburg nuclear physics institute + 188350 , gatchina , st.petersburg , russia . + e - mail : [email protected] + e - mail : [email protected] .
And you have already written the first three sentences of the full article: the interaction of the soft pions at the comparatively low energies is described by the effective lagrangian @xmath0,\ ] ] including three isovector pion fields @xmath1 , @xmath2 , and an auxiliary scalar field @xmath3 obeying the constraint @xmath4 where @xmath5 mev is the pion decay constant . the pion field represents the chiral phase of the quark condensate , that is why the parameterization through the unitary matrix is quite natural in this approach .
constructing the matrix @xmath6 the lagrangian ( [ lpi ] ) takes the form @xmath7 the lagrangian ( [ leff ] ) involves non - linear terms responsible for the many - pion interaction and allows for the classical solutions .
the important class of plane wave type solutions for the pion field was described by a.a.anselm @xcite , the disoriented chiral condensate ( dcc ) being the particular case of it with the wave vector @xmath8 @xcite . in the collision of high energy particles ( or , better , heavy ions ).
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the system is `` warmed up '' to the temperatures at which the chiral symmetry is restored .
then , in the course of cooling , the symmetry breaks again and the scalar , @xmath9 , or pseudoscalar , @xmath10 , condensate with the quantum numbers of @xmath3 or @xmath11 mesons settles out . all four orientation ( 3 pions and @xmath3-meson )
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Suppose that you have an abstract for a scientific paper: the paper considers the problem of implementation on graphics processors of numerical integration routines for higher order finite element approximations .
the design of suitable gpu kernels is investigated in the context of general purpose integration procedures , as well as particular example applications .
the most important characteristic of the problem investigated is the large variation of required processor and memory resources associated with different degrees of approximating polynomials .
the questions that we try to answer are whether it is possible to design a single integration kernel for different gpus and different orders of approximation and what performance can be expected in such a case .
finite element method , higher order approximation , numerical integration , graphics processors , gpu , opencl .
And you have already written the first three sentences of the full article: in recent years graphics processors ( gpus ) have gained widespread acceptance as an architecture useful for scientific computing . in many application domains their use brings manyfold increase in performance @xcite .
most often gpus are used for computational kernels , the most computationally intensive parts of applications . in the finite element method ( fem )
domain , the first cited case of using gpus is @xcite where finite elements are applied in interactive visualisation ..
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other examples include implementation for gpu clusters of higher order fem approximations in earthquake modelling and wave propagation problems @xcite or gpu implementations of some variants of discontinuous galerkin approximation @xcite .
the finite element solution process can be divided into two parts : creation of the matrix for the system of linear equations , based on a suitable weak statement of the approximated problem and the solution of the system of equations ( or some update of the vector of global degrees of freedom , based on the created matrix or several matrices like e.g. for certain time stepping schemes and the right hand side vector ) .
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Suppose that you have an abstract for a scientific paper: we firstly revisit the importance , naturalness and limitations of the so - called optical metrics for describing the propagation of light rays in the limit of geometric optics .
we then exemplify their flexibility and nontriviality in some nonlinear material media and in the context of nonlinear theories of the electromagnetism , both in presence of curved backgrounds , where optical metrics could be flat and inaccessible regions for the propagation of photons could be conceived , respectively .
finally , we underline and discuss the relevance and potential applications of our analyses in a broad sense , ranging from material media to compact astrophysical systems . .
And you have already written the first three sentences of the full article: it is very well - known that light propagation in the limit of geometric optics can be described by fermat s principle @xcite .
it states that the trajectories of rays can be obtained by the extremization of their optical paths @xcite .
geodesics in a spacetime are obtained likewise , by extremizing the distance between two given spacetime events ..
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this means that these two issues are intimately related ( @xcite , page 127 , and references therein ) and aspects raising in one area should be obtained in the other .
this must be specially the case for the spacetime metric .
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Suppose that you have an abstract for a scientific paper: analyses of recent helioseismic data indicate that the dynamical regimes at the base of the convection zone can be different from those observed at the top , having either significantly shorter periods or non periodic behaviour .
recently spatiotemporal fragmentation / bifurcation has been proposed as a dynamical mechanism to account for the multi - mode behaviour that is possibly observed in the solar convection zone , without requiring separate physical mechanisms with different time scales at different depths . here
we study the robustness of this mechanism with respect to changes to the zero order rotation profile , motivated by the uncertainties of and differences between the various reductions of the helioseimic data .
we find that spatiotemporal fragmentation is a common feature of the reductions investigated . .
And you have already written the first three sentences of the full article: recent analyses of the helioseismic data , from both the michelson doppler imager ( mdi ) instrument on board the soho spacecraft ( toomre et al .
2000 ) and the global oscillation network group ( gong ) project ( antia & basu 2000 ) , have provided strong evidence that the previously observed torsional oscillations ( e.g. howard & labonte 1980 ; snodgrass , howard & webster 1985 ; kosovichev & schou 1997 ; schou et al .
1998 ) , with periods of about 11 years , penetrate into the convection zone to depths of at least 10 percent in radius ..
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further studies of these data have produced interesting , but rather inconsistent results .
in particular , howe et al .
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Suppose that you have an abstract for a scientific paper: we analyze the hawking radiation process due to collapsing configurations in the presence of superluminal modifications of the dispersion relation . with such superluminal dispersion relations ,
the horizon effectively becomes a frequency - dependent concept .
in particular , at every moment of the collapse , there is a critical frequency above which no horizon is experienced .
we show that , as a consequence , the late - time radiation suffers strong modifications , both quantitative and qualitative , compared to the standard hawking picture .
concretely , we show that the radiation spectrum becomes dependent on the measuring time , on the surface gravities associated with different frequencies , and on the critical frequency .
even if the critical frequency is well above the planck scale , important modifications still show up . .
And you have already written the first three sentences of the full article: phenomenological approaches to quantum gravity have recently started to develop in parallel with the more traditional attempts to construct such a theory from first principles . in particular , increasing attention has focused on the consideration that maybe lorentz invariance is not a fundamental law , but an effective low - energy symmetry which is broken at high energies ( see , e.g. , @xcite for a general introduction ) .
conceptually speaking , in quantum gravity theories from first principles , it is not really clear whether lorentz invariance is fundamental or effective , and in the latter case , how its breaking scale is related to the planck scale .
for example , while many string theory scenarios axiomatically incorporate lorentz invariance , it has been argued that in certain situations , violations of lorentz invariance may occur in a way consistent with world - sheet conformal invariance @xcite , thus leading to acceptable string theory backgrounds . in the context of loop quantum gravity , in @xcite.
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it has been argued that quantum effects should modify the relativistic dispersion relations , although the issue seems far from settled ( see @xcite for some general remarks ) . in scenarios of emergent gravity based on condensed matter analogies @xcite ,
the situation is clearer : lorentz invariance is a low - energy effective symmetry , and so it is expected to break at some scale , although not necessarily related to ( and therefore possibly much higher than ) the planck scale @xcite .
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Suppose that you have an abstract for a scientific paper: we consider a suspended elastic rod under longitudinal compression . the compression can be used to adjust potential energy for transverse displacements from harmonic to double well regime . as compressional strain
is increased to the buckling instability , the frequency of fundamental vibrational mode drops continuously to zero ( first buckling instability ) . as one tunes the separation between ends of a rod , the system remains stable beyond the instability and develops a double well potential for transverse motion .
the two minima in potential energy curve describe two possible buckled states at a particular strain . from one buckled state it can go over to the other by thermal fluctuations or quantum tunnelling . using a continuum approach and transition state theory ( tst )
one can calculate the rate of conversion from one state to other .
saddle point for the change from one state to other is the straight rod configuration .
the rate , however , diverges at the second buckling instability . at this point ,
the straight rod configuration , which was a saddle till then , becomes hill top and two new saddles are generated .
the new saddles have bent configurations and as rod goes through further instabilities , they remain stable and the rate calculated according to harmonic approximation around saddle point remains finite . in our earlier paper classical rate calculation including friction has been carried out [ j. comput .
theor . nanosci .
* 4 * ( 2007 ) _ 1 _ ] , by assuming that each segment of the rod is coupled to its own collection of harmonic oscillators - our rate expression is well behaved through the second buckling instability . in this paper
we have extended our method to calculate quantum rate using the same system plus reservoir model .
we find that friction lowers the rate of conversion . .
And you have already written the first three sentences of the full article: considerable attention has recently been paid to two - state nano - mechanical systems @xcite and the possibility of observing quantum effects in them . in the experiments of rueckes _ et al . _
@xcite crossed carbon nano - tubes were suspended between supports and the suspended element was electrostatically flexed between two states .
_ @xcite propose to use an electrostatically flexed cantilever to explore the possibility of macroscopic quantum tunnelling in a nano - mechanical system ..
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@xcite suggest using the two buckled states of a nanorod as the two states and investigate the possibility of observing quantum effects . here
we consider a suspended elastic rod of rectangular cross section under longitudinal compression .
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Suppose that you have an abstract for a scientific paper: motion in the atmosphere or mantle convection are two among phenomena of natural convection induced by internal heat sources .
they bifurcate from the conduction state as a result of its loss of stability . in spite of their importance , due to the occurrence of variable coefficients in the nonlinear partial differential equations governing the evolution of the perturbations around the basic equilibrium ,
so far these phenomena were treated mostly numerically and experimentally .
no rigorous study is known . in this paper
we realize for the first time such a linear study for the eigenvalue problem associated with those equations for a convection problem with an uniform internal heat source in a horizontal fluid layer bounded by two rigid walls .
our method uses fourier series expansions for the unknown functions .
numerical results and graphs are given showing a destabilizing effect of the presence of the heat source . .
And you have already written the first three sentences of the full article: problems of convection induced by an internal heat source have been experimentally ( e.g. [ 5 ] ) and numerically ( e.g. [ 4 ] ) studied by many researchers .
the investigations concerned the effects of the heating and cooling rate , many investigations were performed for different conditions imposed on the lower and upper boundaries . in these cases
it is difficult to compare the evaluations of the heat fluxes in the heated fluid layer with the ones from the classical convection . the extent of the convection cells when the rayleigh number increases are greater than the ones in the classical rayleigh - bnard convection problem ..
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these problems are very important for the study of the motion in the atmosphere , influencing all other processes that take place here . in this paper a horizontal layer of viscous incompressible fluid with constant viscosity and thermal conductivity coefficients @xmath0 and @xmath1 is considered [ 6 ] . in this context , the heat and hydrostatic transfer equations [ 6 ] are @xmath2 @xmath3 where @xmath4 is the heating rate , @xmath5 , @xmath6 and @xmath7 are the potential temperature , pressure and density in the basic state . in the fluid ,
the temperature at all point varies at the same rate as the boundary temperature , so the problem is characterized by a constant potential temperature difference between the lower and the upper boundaries @xmath8 .
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Suppose that you have an abstract for a scientific paper: a number of important results of studying large deformations of hyper - elastic shells are obtained using discrete methods of mathematical physics @xcite@xcite . in the present paper , using the variational method for solving nonlinear boundary problems of statics of hyper - elastic membranes under the regular hydrostatic load , we investigate peculiarities of deformation of a circular membrane whose mechanical characteristics are described by the bidermann - type elastic potential .
we develop an algorithm for solving a singular perturbation of nonlinear problem for the case of membrane loaded by heavy liquid .
this algorithm enables us to obtain approximate solutions both in the presence of boundary layer and without it .
the class of admissible functions , on which the variational method is realized , is chosen with account of the structure of formal asymptotic expansion of solutions of the corresponding linearized equations that have singularities in a small parameter at higher derivatives and in the independent variable .
we give examples of calculations that illustrate possibilities of the method suggested for solving the problem under consideration .
journal of nonlinear mathematical physics 1999 , v.6 , n 1 , . [ multiblock footnote omitted ] * variational methods for solving + nonlinear boundary problems of + statics of hyper - elastic membranes * [ trotsenko - fp ] _ v.a .
trotsenko _ _ institute of mathematics of the national academy of sciences of ukraine , + 3 tereshchenkivska str . , 252601 kyiv-4 , ukraine _ _ received june 10 , 1998 ; accepted july 13 , 1998 _ .
And you have already written the first three sentences of the full article: let us consider a circular membrane of the radius @xmath0 of incompressible , isotropic and hyperelastic material having the small constant width @xmath1 .
let a hydrostatic load @xmath2 be applied to the membrane with an inflexibly fixed contour . to describe the geometry of the deformed membrane ,
let us introduce the cylindrical coordinate system @xmath3 , the axis @xmath4 of which coincides with the symmetry axis of the membrane ..
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it follows from the axial symmetry of the problem that principal deformation directions at any point will coincide with meridians , parallels and normals to the deformed surface and all the parameters of the strained deformed state will be functions of initial distances @xmath5 of points of the membrane from its symmetry axis only .
denote the principal degrees of lengthenings in these directions by @xmath6 , @xmath7 and @xmath8 , respectively .
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Suppose that you have an abstract for a scientific paper: the paper gives an overview of strangeness - production experiments at the cooler synchrotron cosy .
results on kaon - pair and @xmath0 meson production in @xmath1 , @xmath2 and @xmath3 collisions , hyperon - production experiments and @xmath4 final - state interaction studies are presented .
address = hiskp , universitt bonn , nussallee 14 - 16 , d 53115 bonn , germany address = fakultt fr physik , universitt duisburg - essen , lotharstr . 1 ,
d 47048 duisburg , germany address = inst .
nucl .
physics , pan , ul .
radzikowskiego 152 , 31 - 342 krakw , poland .
And you have already written the first three sentences of the full article: the cooler synchrotron cosy @xcite at the forschungszentrum jlich in germany can accelerate protons and deuterons up to about 3.7 gev / c .
both , unpolarized and polarized beams are available .
excellent beam quality can be achieved using electron- and/or stochastic cooling ..
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cosy can be used as an accelerator for external target experiments and as storage ring for internal target experiments .
the strangeness production experiments have been performed at the internal spectrometer anke by the cosy - anke collaboration , at the internal cosy-11 spectrometer by the cosy-11 collaboration , at the external tof facility by the cosy - tof collaboration and at the external big karl spectrometer by the cosy - momo and cosy - hires collaborations .
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Suppose that you have an abstract for a scientific paper: in this note we describe a relation between euler s elasticae and sub - riemannian geodesics on @xmath0 . analyzing the hamiltonian system of pontryagin maximum principle
we show that these two curves coincide only in the case when they are segments of a straight line . +
* keywords : * elastica , sub - riemannian geodesic , group of rototranslations . .
And you have already written the first three sentences of the full article: in this paper we consider two classical geometric control problems @xcite : the problem of euler s elasticae and the problem of sub - riemannian ( sr ) geodesics on @xmath0 .
solution curves to both problems have many applications in mechanics @xcite , robotics @xcite , image processing @xcite and modelling of human visual system @xcite .
although solutions are well known in geometric control community , the authors have noticed a common confusion in applied societies where people sometimes mix these two curves ..
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the reason is that the formulation of the problems is very similar , and at first sight one can wrongly deduce that euler s elasticae are obtained via reparametrization of sr - geodesics by arclength . to prevent this possible confusion we clarify that these two curves coincide only in the case of straight line .
the structure of the paper is the following .
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Suppose that you have an abstract for a scientific paper: the mission of nasa s terrestrial planet finder ( tpf ) is to find earth - like planets orbiting other stars and characterize the atmospheres of these planets using spectroscopy .
because of the enormous brightness ratio between the star and the reflected light from the planet , techniques must be found to reduce the brightness of the star . the current favorite approach to doing
this is with interferometry : interfering the light from two or more separated telescopes with a @xmath0 phase shift , nulling out the starlight .
while this technique can , in principle , achieve the required dynamic range , building a space interferometer that has the necessary characteristics poses immense technical difficulties . in this paper
, we suggest a much simpler approach to achieving the required dynamic range . by simply adjusting the transmissive shape of a telescope aperture
, the intensity in large regions around the stellar image can be reduced nearly to zero .
this approach could lead to construction of a tpf using conventional technologies , requiring space optics on a much smaller scale than the current tpf approach .
subject headings : astronomical instrumentation instrumentation : interferometers techniques : interferometric stars stars : imaging stars : planetary systems .
And you have already written the first three sentences of the full article: the mission of the terrestrial planet finder ( tpf ) is to find earth - like planets orbiting other stars by imaging , and to determine their atmospheric constituents by spectral analysis of their reflected light ( beichman 1999 ) .
imaging provides separation of the light reflected from the planet from that of the star . because the star is so bright compared to the planet ,
the dynamic range required is of order @xmath1 at visible wavelengths ..
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the `` book '' approach proposed for tpf is to operate in the infrared ( 7 to 14 microns ) where the dynamic range required is `` only '' @xmath2 . however , working in the ir increases the resolution requirement of the telescope or interferometer needed to separate the image of the planet from the image of the star .
a 20 meter interferometer baseline or telescope diameter may be sufficient in the visible band , but in the ir , a 200 meter telescope or 200 meter baseline interferometer is required .
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Suppose that you have an abstract for a scientific paper: it is demonstrated how the non - proprietary openacc standard of compiler directives may be used to compactly and efficiently accelerate the rate - determining steps of two of the most routinely applied many - body methods of electronic structure theory , namely the second - order mller - plesset ( mp2 ) model in its resolution - of - the - identity ( ri ) approximated form and the ( t ) triples correction to the coupled cluster singles and doubles model ( ccsd(t ) ) . by means of compute directives as well as the use of optimized device math libraries , the operations involved in the energy kernels have been ported to graphics processing unit ( gpu ) accelerators , and the associated data transfers correspondingly optimized to such a degree that the final implementations ( using either double and/or single precision arithmetics ) are capable of scaling to as large systems as allowed for by the capacity of the host central processing unit ( cpu ) main memory .
the performance of the hybrid cpu / gpu implementations is assessed through calculations on test systems of alanine amino acid chains using one - electron basis sets of increasing size ( ranging from double- to pentuple-@xmath0 quality ) . for all but the smallest problem sizes of the present study ,
the optimized accelerated codes ( using a single multi - core cpu host node in conjunction with six gpus ) are found to be capable of reducing the total time - to - solution by at least an order of magnitude over optimized , openmp - threaded cpu - only reference implementations . .
And you have already written the first three sentences of the full article: when formulating the criteria for what defines _
portable _ source code , one tends to draw a distinction between two types of portability , namely that associated with functionality and that associated with performance . while the former of these covers
what is perhaps usually implied when referring to code portability , i.e. , the ability of a single code to run anywhere ( rebuild the code on various architectures , the code will run and produce correct results ) , the latter , the existence of which have often been declared a fallacy , relates to the ability of a single code to run productively anywhere , i.e. , achieving , say , @xmath1 of the hand - tuned performance on any given architecture . as such.
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, making a code portable will often result in a compromise between superior performance on a single platform and decent performance on all potential platforms .
one possible way of circumventing this problem is by cluttering the source code with multiple conditional preprocessor directives and retain architecture - specific versions of key kernels with vendor - specific intrinsics .
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11,498 |
Suppose that you have an abstract for a scientific paper: we present observations at 1.2 mm with mambo - ii of a sample of @xmath0 radio - intermediate obscured quasars , as well as co observations of two sources with the plateau de bure interferometer .
the typical rms noise achieved by the mambo observations is 0.55 mjy beam@xmath1 and 5 out of 21 sources ( 24% ) are detected at a significance of @xmath2 . stacking all sources leads to a statistical detection of @xmath3 mjy and stacking only the non - detections also yields a statistical detection , with @xmath4 mjy . at the typical redshift of the sample , @xmath5 , 1 mjy corresponds to a far - infrared luminosity @xmath6@xmath7 .
if the far - infrared luminosity is powered entirely by star - formation , and not by agn - heated dust , then the characteristic inferred star - formation rate is @xmath8700 .
this far - infrared luminosity implies a dust mass of @xmath9@xmath10 , which is expected to be distributed on @xmath8kpc scales .
we estimate that such large dust masses on kpc scales can plausibly cause the obscuration of the quasars . combining our observations at 1.2 mm with mid- and far - infrared data , and additional observations for two objects at 350 @xmath11 m using sharc - ii
, we present dust seds for our sample and derive a mean sed for our sample .
this mean sed is not well fitted by clumpy torus models , unless additional extinction and far - infrared re - emission due to cool dust are included .
this additional extinction can be consistently achieved by the mass of cool dust responsible for the far - infrared emission , provided the bulk of the dust is within a radius @xmath82 - 3 kpc .
comparison of our sample to other samples of @xmath12 quasars suggests that obscured quasars have , on average , higher far - infrared luminosities than unobscured quasars . there is a hint that the host galaxies of obscured quasars must have higher cool - dust masses and are therefore often found at an earlier evolutionary phase than those of unobscured quasars . for one source at....
And you have already written the first three sentences of the full article: quasars are believed to be powered by supermassive black holes ( smbhs ) rapidly growing by accreting matter at a large fraction of their eddington rate which , assuming the typical quasar sed of @xcite , corresponds to @xmath30 . we will therefore also refer to obscured agns as obscured quasars if they have @xmath30 . ] .
the accreted matter forms a disk , is heated to temperatures of @xmath31 k , and emits thermal emission at optical and ultraviolet wavelengths .
clouds of gas ionised by this radiation will emit line radiation , and lines which are relatively close to the black hole have rapid orbits which will show broad velocity dispersions ( @xmath322000 km s@xmath1 ) , while clouds further away will show narrower lines ..
Please generate the next two sentences of the article
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dust can survive when the equilibrium temperature with the ultraviolet photons is @xmath332000 k. this dust absorbs optical and ultraviolet radiation and re - emits it at infrared wavelengths characteristic of the dust temperature .
if the line of sight of an observer to the central region is blocked by dust , the optical and ultraviolet continuum , as well as the broad lines , will not be observable .
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11,499 |
Suppose that you have an abstract for a scientific paper: this paper is the first part of a work which consists in proving the stabilization to zero of a fluid - solid system , in dimension 2 and 3 . the considered system couples a deformable solid and a viscous incompressible fluid which satisfies the incompressible navier - stokes equations . by deforming itself
, the solid can interact with the environing fluid and then move itself .
the control function represents nothing else than the deformation of the solid in its own frame of reference .
we there prove that the velocities of the linearized system are stabilizable to zero with an arbitrary exponential decay rate , by a boundary deformation velocity which can be chosen in the form of a feedback operator .
we then show that this boundary feedback operator can be obtained from an internal deformation of the solid which satisfies the linearized physical constraints that a _ self - propelled _ solid has to satisfy . sbastien court ( communicated by the associate editor name ) .
And you have already written the first three sentences of the full article: in this two - part work we are interested in the way a solid immersed in a viscous incompressible fluid ( in dimension 2 or 3 ) can deform itself and then interact with the environing fluid in order to stabilize exponentially to zero the velocity of the fluid and also its own velocities . the domain occupied by the solid at time @xmath0
is denoted by @xmath1 .
we assume that @xmath2 , where @xmath3 is a bounded smooth domain ..
Please generate the next two sentences of the article
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the fluid surrounding the solid occupies the domain @xmath4 .
( 0,0)(-100,-90 ) ( 0,0)(0,0)[lb ] ( 80,-30)(0,0)[lb ] ( -20,25)(0,0)[lb ] the movement of the solid in the inertial frame of reference is described through the time by a lagrangian mapping denoted by @xmath5 , so we have @xmath6 the mapping @xmath7 can be decomposed as follows @xmath8 where the vector @xmath9 describes the position of the center of mass and @xmath10 is the rotation associated with the angular velocity of the solid . in dimension 3
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